CD38
ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase 1 (EC 3.2.2.6) (2'-phospho-ADP-ribosyl cyclase) (2'-phospho-ADP-ribosyl cyclase/2'-phospho-cyclic-ADP-ribose transferase) (EC 2.4.99.20) (2'-phospho-cyclic-ADP-ribose transferase) (ADP-ribosyl cyclase 1) (ADPRC 1) (Cyclic ADP-ribose hydrolase 1) (cADPr hydrolase 1) (T10) (CD38 antigen)
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Short telomeres are a principal defining feature of telomere biology disorders, such as dyskeratosis congenita (DC), for which there are no effective treatments. Here, we report that primary fibroblasts from DC patients and late generation telomerase knockout mice display lower nicotinamide adenine dinucleotide (NAD) levels, and an imbalance in the NAD metabolome that includes elevated CD38 NADase and reduced poly(ADP-ribose) polymerase and SIRT1 activities, respectively, affecting many associated biological pathways. Supplementation with the NAD precursor, nicotinamide riboside, and CD38 inhibition improved NAD homeostasis, thereby alleviating telomere damage, defective mitochondrial biosynthesis and clearance, cell growth retardation, and cellular senescence of DC fibroblasts. These findings reveal a direct, underlying role of NAD dysregulation when telomeres are short and underscore its relevance to the pathophysiology and interventions of human telomere-driven diseases.
Keywords
- CD38 NADase
- NAD metabolism
- mitochondrial impairment
- replicative senescence
- telomere biology disorders
Aging is a complex process that involves dysfunction on multiple levels, all of which seem to converge on inflammation. Macrophages are intimately involved in initiating and resolving inflammation, and their dysregulation with age is a primary contributor to inflammaging-a state of chronic, low-grade inflammation that develops during aging. Among the age-related changes that occur to macrophages are a heightened state of basal inflammation and diminished or hyperactive inflammatory responses, which seem to be driven by metabolic-dependent epigenetic changes. In this review article we provide a brief overview of mitochondrial functions and age-related changes that occur to macrophages, with an emphasis on how the inflammaging environment, senescence, and NAD decline can affect their metabolism, promote dysregulation, and contribute to inflammaging and age-related pathologies.
Keywords
- CD38
- NAD
- SASP
- aging
- immunometabolism
- inflammaging
- macrophage
- mitochondria
- monocyte
- senescence
Pathogenesis of chronic obstructive pulmonary disease (COPD) is dependent on chronic inflammation and is hypothesized to represent organ-specific senescence phenotype. Identification of senescence-associated gene drivers for the development of COPD is warranted. By employing automated pipeline, we have compiled lists of the genes implicated in COPD ([i]N[/i] = 918) and of the genes changing their activity along with cell senescence ([i]N[/i] = 262), with a significant ([i]p[/i] < 7.06e ) overlap between these datasets ([i]N[/i] = 89). A mega-analysis and a partial mega-analysis were conducted for gene sets linked to senescence but not yet to COPD, in nine independent mRNA expression datasets comprised of tissue samples of COPD cases ([i]N[/i] = 171) and controls ([i]N[/i] = 256). Mega-analysis of expression has identified [i]CD38[/i] and [i]TNFRSF12A[/i] ([i]p[/i] < 2.12e ) as genes not yet explored in a context of senescence-COPD connection. Functional pathway enrichment analysis allowed to generate a model, which explains accelerated aging phenotypes previously observed in COPD patients. Presented results call for investigation of the role of TNFRSF12A/CD38 balance in establishing a vicious cycle of unresolvable tissue remodeling in COPD lungs.
Keywords
- aging
- chronic inflammation
- lung
- network analysis
- senescence
- tissue remodeling
During aging, organs such as skeletal muscle and heart require sufficient NAD both as a coenzyme for oxidative-reductive electron transfer and as a substrate for multiple signaling pathways. Sirtuins (SIRTs), a family of NAD -dependent deacetylase, play an important role in regulating mitochondrial homeostasis and antioxidant defense by deacetylating transcription factors and enzymes such as PGC-1α, p65, GCN5, and SOD2. However, age-related DNA damage and increased SASP activate PARP-1 and CD38, the enzymes competing with SIRTs for NAD . Thus, it is important to know how aging alters intracellular NAD status and NAD -depending enzyme expression in muscles. In this study, we report that the acetylation level of muscle protein pool, as well as major SIRTs target proteins (PGC-1α, GCN5, p65, and SOD2), was significantly increased in hindlimb and cardiac muscles of 24-month old mice compared with their 6-month old counterparts, despite the fact that most members of the SIRT family were upregulated with aging. Aging increased the protein content of PARP-1 and CD38, whereas decreased NAD levels in both skeletal and heart muscles. Aged muscles demonstrated clear signs of mitochondrial dysfunction, oxidative stress, and inflammation. Taken together, our data suggest that despite the upregulation of SIRTs, aged muscles suffered from NAD deficit partly due to the competition of elevated CD38 and PARP-1. The enhanced acetylation of several key proteins involved in broad cellular functions may contribute to the age-related muscle deterioration.
Keywords
- Aging
- CD38
- Deacetylation
- NAD
- PARP
- SIRT
- Skeletal muscle
Neurodegenerative diseases are characterized by neuronal degeneration as well as neuroinflammation. While CD38 is strongly expressed in brain cells including neurons, astrocytes as well as microglial cells, the role played by CD38 in neurodegeneration and neuroinflammation remains elusive. Yet, CD38 expression increases as a consequence of aging which is otherwise the primary risk associated with neurodegenerative diseases, and several experimental data demonstrated that CD38 knockout mice are protected from neurodegenerative and neuroinflammatory insults. Moreover, nicotinamide adenine dinucleotide, whose levels are tightly controlled by CD38, is a recognized and potent neuroprotective agent, and NAD supplementation was found to be beneficial against neurodegenerative diseases. The aims of this review are to summarize the physiological role played by CD38 in the brain, present the arguments indicating the involvement of CD38 in neurodegeneration and neuroinflammation, and to discuss these observations in light of CD38 complex biology.
Keywords
- ALS.
- Alzheimer’s disease
- CD38
- NAD
- Parkinson’s disease
- aging
- neurodegeneration
- neuroinflammation
CD38 is a multifunctional cell surface protein endowed with receptor/enzymatic functions. The protein is generally expressed at low/intermediate levels on hematological tissues and some solid tumors, scoring the highest levels on plasma cells (PC) and PC-derived neoplasia. CD38 was originally described as a receptor expressed by activated cells, mainly T lymphocytes, wherein it also regulates cell adhesion and cooperates in signal transduction mediated by major receptor complexes. Furthermore, CD38 metabolizes extracellular NAD , generating ADPR and cyclic ADPR. This ecto-enzyme controls extra-cellular nucleotide homeostasis and intra-cellular calcium fluxes, stressing its relevance in multiple physiopathological conditions (infection, tumorigenesis and aging). In clinics, CD38 was adopted as a cell activation marker and in the diagnostic/staging of leukemias. Quantitative surface CD38 expression by multiple myeloma (MM) cells was the basic criterion used for therapeutic application of anti-CD38 monoclonal antibodies (mAbs). Anti-CD38 mAbs-mediated PC depletion in autoimmunity and organ transplants is currently under investigation. This review analyzes different aspects of CD38's role in regulatory cell populations and how these effects are obtained. Characterizing CD38 functional properties may widen the extension of therapeutic applications for anti-CD38 mAbs. The availability of therapeutic mAbs with different effects on CD38 enzymatic functions may be rapidly translated to immunotherapeutic strategies of cell immune defense.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Antibodies, Monoclonal
- B-Lymphocytes, Regulatory
- Cell Line
- Extracellular Vesicles
- Humans
- Infections
- Membrane Glycoproteins
- Mice
- Neoplasms
- T-Lymphocytes, Regulatory
Keywords
- CD38
- adenosine
- immune-modulation
- regulatory cells
Intestinal lamina propria (LP) CD4 T cells play critical roles in maintaining intestinal homeostasis and in immune responses to enteric microbes, yet little is known regarding whether they contribute to age-associated intestinal immune dysfunction. In this study, we evaluated the direct ex vivo frequency, activation/inhibitory phenotype, death profiles, and in vitro functional responses of human jejunum LP CD4 T cells, including Th1, Th17, and Th22 subsets isolated from younger (<45 years) and older (>65years) persons. Expression of the co-inhibitory molecule CTLA-4 was significantly lower in older CD4 T cells, whereas expression of HLA-DR, CD38, CD57, and PD-1 were not significantly different between groups. Total CD4 T cell frequencies were similar between age groups, but lower frequencies and numbers of Th17 cells were observed directly ex vivo in older samples. Older Th17 and Th1 cells proliferated to a lesser degree following in vitro exposure to bacterial antigens vs. their younger counterparts. Levels of spontaneous cell death were increased in older CD4 T cells; however, cellular death profiles following activation did not differ based on age. Thus, small intestinal CD4 T cells from older persons have altered phenotypic and functional profiles including reduced expression of a co-inhibitory molecule, increased spontaneous cell death, and both reduced frequencies and altered functional responses of specific Th cell subsets. These changes may contribute to altered intestinal homeostasis and loss of protective gut immunity with aging.
MeSH Terms
- Adolescent
- Adult
- Age Factors
- Aged
- Aged, 80 and over
- CD4-Positive T-Lymphocytes
- Female
- Gastrointestinal Microbiome
- Humans
- Interleukin-17
- Intestinal Mucosa
- Male
- Middle Aged
- Phenotype
- Th1 Cells
- Th17 Cells
- Young Adult
Keywords
- T helper cells
- aging
- gut
- human
Our previous research showed that CD38 played vital roles in Ang-II induced hypertrophy and high fat diet induced heart injury. However, the role of CD38 in heart aging is still unknown. In the present study, we reported that CD38 knockdown significantly protected cardiomyocytes from D-galactose (D-gal)-induced cellular senescence. Cellular senescence was evaluated by [i]β[/i]-galactosidase staining, the expressions of genes closely related to aging including p16 and p21, and the ROS production, MDA content and the expressions of oxidant stress related genes were examined by biochemical analysis, Western blot and QPCR. Our results showed that the expression of CD38 was increased in H9c2 cells after D-gal treatment and the expressions of NAMPT and Sirt1 were downregulated in heart tissue from old mice. CD38 knockdown significantly reduced the number of SA-[i]β[/i]-gal-positive cells and the expressions of p16 and p21 in H9c2 cells with or without D-gal treatment. The acetylation level of total protein was decreased in CD38 knockdown group, but the expression of Sirt3 was increased in CD38 knockdown group treated with D-gal. In addition, knockdown of CD38 significantly attenuated D-gal induced ROS production, MDA content and NOX4 expression in the cells. Inhibition Sirt1 partially reversed the effects of CD38 knockdown on D-gal induced senescence and oxidative stress. Furthermore, NAD supplementation reduced D-gal induced cellular senescence, ROS production and MDA content. The expression of SOD2 was increased and the NOX4 expression was decreased in H9c2 cells after NAD supplementation. Taken together, our results demonstrated that CD38 knockdown alleviated D-gal induced cell senescence and oxidative stress via NAD /Sirt1 signaling pathway.
Keywords
- CD38
- D-galactose
- NAD
- heart senescence
- oxidative stress
Nicotinamide adenine dinucleotide (NAD) is an important coenzyme that regulates various metabolic pathways, including glycolysis, β-oxidation, and oxidative phosphorylation. Additionally, NAD serves as a substrate for poly(ADP-ribose) polymerase (PARP), sirtuin, and NAD glycohydrolase, and it regulates DNA repair, gene expression, energy metabolism, and stress responses. Many studies have demonstrated that NAD metabolism is deeply involved in aging and aging-related diseases. Previously, we demonstrated that nicotinamide guanine dinucleotide (NGD) and nicotinamide hypoxanthine dinucleotide (NHD), which are analogs of NAD, are significantly increased in Nmnat3-overexpressing mice. However, there is insufficient knowledge about NGD and NHD in vivo. In the present study, we aimed to investigate the metabolism and biochemical properties of these NAD analogs. We demonstrated that endogenous NGD and NHD were found in various murine tissues, and their synthesis and degradation partially rely on Nmnat3 and CD38. We have also shown that NGD and NHD serve as coenzymes for alcohol dehydrogenase (ADH) in vitro, although their affinity is much lower than that of NAD. On the other hand, NGD and NHD cannot be used as substrates for SIRT1, SIRT3, and PARP1. These results reveal the basic metabolism of NGD and NHD and also highlight their biological function as coenzymes.
MeSH Terms
- Aging
- Animals
- Guanine Nucleotides
- Guanosine Triphosphate
- Inosine Triphosphate
- Mice
- NAD
- Poly(ADP-ribose) Polymerases
- Sirtuins
CD38 (Cluster of Differentiation 38) is a multifunctional ecto-enzyme that metabolizes NAD and mediates nicotinamide dinucleotide (NAD ) and extracellular nucleotide homeostasis as well as intracellular calcium. CD38 is also an emerging therapeutic target under conditions in which metabolism is altered including infection, aging, and tumorigenesis. We describe multiple enzymatic activities of CD38, which may explain the breadth of biological roles observed for this enzyme. Of greatest significance is the role of CD38 as an ecto-enzyme capable of modulating extracellular NAD precursor availability: 1 to bacteria unable to perform de novo synthesis of NAD ; and 2 in aged parenchyma impacted by the accumulation of immune cells during the process of 'inflammaging'. We also discuss the paradoxical role of CD38 as a modulator of intracellular NAD , particularly in tumor immunity. Finally, we provide a summary of therapeutic approaches to CD38 inhibition and 'NAD boosting' for treatment of metabolic dysfunction observed during aging and in tumor immunity. The present review summarizes the role of CD38 in nicotinamide nucleotide homeostasis with special emphasis on the role of CD38 as an immunomodulator and druggable target.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Homeostasis
- Humans
- Immunity
- Immunomodulation
- Metabolic Diseases
- Neoplasms
Keywords
- CD38
- NAD
- NADase
- aging
- cancer
- macrophages
- metabolism
- senescence
During human aging, decrease of NAD levels is associated with potentially reversible dysfunction in the liver, kidney, skeletal and cardiac muscle, endothelial cells, and neurons. At the same time, the number of senescent cells, associated with damage or stress that secretes proinflammatory factors (SASP or senescence-associated secretory phenotype), increases with age in many key tissues, including the kidneys, lungs, blood vessels, and brain. Senescent cells are believed to contribute to numerous age-associated pathologies and their elimination by senolytic regimens appears to help in numerous preclinical aging-associated disease models, including those for atherosclerosis, idiopathic pulmonary fibrosis, diabetes, and osteoarthritis. A recent report links these processes, such that decreased NAD levels associated with aging may attenuate the SASP potentially reducing its pathological effect. Conversely, increasing NAD levels by supplementation or genetic manipulation, which may benefit tissue homeostasis, also may worsen SASP and encourage tumorigenesis at least in mouse models of cancer. Taken together, these findings suggest a fundamental trade-off in treating aging-related diseases with drugs or supplements that increase NAD . Even more interesting is a report that senescent cells can induce CD38 on macrophages and endothelial cells. In turn, increased CD38 expression is believed to be the key modulator of lowered NAD levels with aging in mammals. So, accumulation of senescent cells may itself be a root cause of decreased NAD , which in turn could promote dysfunction. On the contrary, the lower NAD levels may attenuate SASP, decreasing the pathological influence of senescence. The elimination of most senescent cells by senolysis before initiating NAD therapies may be beneficial and increase safety, and in the best-case scenario reduce the need for NAD supplementation.
MeSH Terms
- Aging
- Animals
- Cellular Senescence
- Humans
- Inflammation
- NAD
Keywords
- NAD
- aging
- cancer
- senescence
Tissue nicotinamide adenine dinucleotide (NAD ) decline has been implicated in aging. We have recently identified CD38 as a central regulator involved in tissue NAD decline during the aging process. CD38 is an ecto-enzyme highly expressed in endothelial and inflammatory cells. To date, the mechanisms that regulate CD38 expression in aging tissues characterized by the presence of senescent cells is not completely understood. Cellular senescence has been described as a hallmark of the aging process and these cells are known to secrete several factors including cytokines and chemokines through their senescent associated secretory phenotype (SASP). Here we investigated if the cellular senescence phenotype is involved in the regulation of CD38 expression and its NADase activity. We observed that senescent cells do not have high expression of CD38. However, the SASP factors secreted by senescent cells induced CD38 mRNA and protein expression and increased CD38-NADase activity in non-senescent cells such as endothelial cells or bone marrow derived macrophages. Our data suggest a link between cellular senescence and NAD decline in which SASP-mediated upregulation of CD38 can disrupt cellular NAD homeostasis.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Cells, Cultured
- Cellular Senescence
- Endothelial Cells
- Female
- Human Umbilical Vein Endothelial Cells
- Humans
- Macrophages
- Mice, Inbred C57BL
- Middle Aged
- NAD
Keywords
- Aging
- CD38
- Inflammaging
- NAD( )
- Senescence
CD38 is a multifunctional enzyme involved in calcium signaling and Nicotinamide Adenine Dinucleotide (NAD ) metabolism. Through its major activity, the hydrolysis of NAD , CD38 helps maintain the appropriate levels of this molecule for all NAD -dependent metabolic processes to occur. Due to current advances and studies relating NAD decline and the development of multiple age-related conditions and diseases, CD38 gained importance in both basic science and clinical settings. The discovery and development of strategies to modulate its function and, possibly, treat diseases and improve health span put CD38 under the spotlights. Therefore, a consistent and reliable method to measure its activity and explore its use in medicine is required. We describe here the methods how our group measures both the hydrolase and cyclase activity of CD38, utilizing a fluorescence-based enzymatic assay performed in a plate reader using 1,N -Ethenonicotinamide Adenine Dinucleotide (ε-NAD) and Nicotinamide Guanine Dinucleotide (NGD) as substrates, respectively.
Keywords
- Aging
- CD38
- Cyclase
- Hydrolase
- NAD
- NADase
- NGD
- ε-NAD
Nicotinamide adenine dinucleotide (NAD ) is an essential pyridine nucleotide that serves as an electron carrier in cellular metabolism and plays a crucial role in the maintenance of balanced redox homeostasis. Quantification of NAD :NADH and NADP :NADPH ratios are pivotal to a wide variety of cellular processes, including intracellular secondary messenger signaling by CD38 glycohydrolases, DNA repair by poly(adenosine diphosphate ribose) polymerase (PARP), epigenetic regulation of gene expression by NAD-dependent histone deacetylase enzymes known as sirtuins, and regulation of the oxidative pentose phosphate pathway. We quantified changes in the NAD metabolome in plasma samples collected from consenting healthy human subjects across a wide age range (20-87 years) using liquid chromatography coupled to tandem mass spectrometry. Our data show a significant decline in the plasma levels of NAD , NADP , and other important metabolites such as nicotinic acid adenine dinucleotide (NAAD) with age. However, an age-related increase in the reduced form of NAD and NADP -NADH and NADPH-and nicotinamide (NAM), N-methyl-nicotinamide (MeNAM), and the products of adenosine diphosphoribosylation, including adenosine diphosphate ribose (ADPR) was also reported. Whereas, plasma levels of nicotinic acid (NA), nicotinamide mononucleotide (NMN), and nicotinic acid mononucleotide (NAMN) showed no statistically significant changes across age groups. Taken together, our data cumulatively suggest that age-related impairments are associated with corresponding alterations in the extracellular plasma NAD metabolome. Our future research will seek to elucidate the role of modulating NAD metabolites in the treatment and prevention of age-related diseases.
MeSH Terms
- Aged
- Aging
- Body Mass Index
- Female
- Humans
- Least-Squares Analysis
- Male
- Metabolome
- Middle Aged
- NAD
- Regression Analysis
- Young Adult
Keywords
- NAD
- aging
- biomarker
- nicotinamide
- plasma
Nicotinamide adenine dinucleotide (NAD ) is an essential redox cofactor and signaling molecule that controls the activity of enzymes involved in metabolism, DNA repair, and cellular survival, such as the PARPs, CD38, and the sirtuins. Here, we describe three methods for measuring the activity of these enzymes: the etheno-NAD assay measures NAD hydrolase activity using an NAD analog to produce a fluorescent product that is measured in real time; the PNC1 assay converts a native product of NAD hydrolysis, nicotinamide, into a quantitative fluorescent readout; and liquid chromatography tandem mass spectrometry (LC-MS/MS) is used to characterize the entire NAD metabolome in a sample. These methods will enable new insights into the roles that NAD and the enzymes that utilize it play in health and disease.
MeSH Terms
- Biological Assay
- Chromatography, Liquid
- Humans
- Hydrolysis
- NAD
- Niacinamide
- Sirtuins
- Tandem Mass Spectrometry
Keywords
- ADP-ribose
- ARTD
- Aging
- BST1
- CD38
- Epigenetics
- HDAC
- Mass spectrometry
- Metabolism
- Metabolomics
- NAD nicotinamide
- PARP
- Sirtuin
Nicotinamide adenine dinucleotide (NAD) plays an essential role in all aspects of human life. NAD levels decrease as humans age, and supplementation with NAD precursors plays a protective role against aging and associated disease. Less is known about the effects of decreased NAD on cellular processes, which is the basis for understanding the relationship between cellular NAD levels and aging-associated disease. In the present study, cellular NAD levels were decreased by overexpression of CD38, a NAD hydrolase, or by treating cells with FK866, an inhibitor of nicotinamide phosphoribosyltransferase (NAMPT). Quantitative proteomics revealed that declining NAD levels downregulated proteins associated with primary metabolism and suppressed cell growth in culture and nude mice. Decreased glutathione synthesis caused a 4-fold increase in cellular reactive oxygen species levels, and more importantly upregulated proteins related to movement and adhesion. In turn, this significantly changed cell morphology and caused cells to undergo epithelial to mesenchymal transition (EMT). Secretomic analysis also showed that decreased NAD triggered interleukin-6 and transforming growth factor beta (TGFβ) secretion, which activated integrin-β-catenin, TGFβ-MAPK, and inflammation signaling pathways to sustain the signaling required for EMT. We further revealed that decreased NAD inactivated sirtuin 1, resulting in increased signal transducer and activator of transcription 3 (STAT3) acetylation and phosphorylation, and STAT3 activation. Repletion of nicotinamide or nicotinic acid inactivated STAT3 and reversed EMT, as did STAT3 inhibition. Taken together, these results indicate that decreased NAD activates multiple signaling pathways to promote EMT and suggests that age-dependent decreases in NAD may contribute to tumor progression. Consequently, repletion of NAD precursors has potential benefits for inhibiting cancer progression.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Acrylamides
- Animals
- Cell Line
- Cell Proliferation
- Epithelial-Mesenchymal Transition
- Female
- Humans
- Integrins
- Mice, Nude
- NAD
- Oxidative Stress
- Piperidines
- Proteome
- Proteomics
- Reactive Oxygen Species
- STAT3 Transcription Factor
- Signal Transduction
Keywords
- Aging
- Cell adhesion
- Epithelial-Mesenchymal Transition
- Lung cancer
- Omics
- Phosphoproteome
- SILAC
- Secretome
This study aimed to evaluate whether ICU patients who developed persistent critical illness displayed an immune profile similar to an aged immune phenotype and any associations with patient outcomes. Twenty two critically ill ICU patients (27-76 years, 15 males), at day 5 of mechanical ventilation, and 22 healthy age-matched controls (27-77 years, 13 males) were recruited. Frequency and phenotype of innate and adaptive immune cells and telomere length in peripheral blood mononuclear cells (PBMCs) were measured. An elevated granulocyte count (p < 0.0001), increased numbers of immature granulocytes (p < 0.0001), increased CD16 monocytes (p = 0.003) and CD14 HLADR monocytes (p = 0.004) and lower NK cell numbers (p = 0.007) were observed in ICU patients compared to controls. Critically ill patients also had lower numbers of total T lymphocytes (p = 0.03), naïve CD4 T cells (p = 0.003) and PTK7 recent thymic emigrants (p = 0.002), and increased senescent CD28 CD57 CD4 T cells (p = 0.02), but there was no difference in PBMC telomere length. Regulatory immune cell frequency was affected with reduced circulating CD19 CD24 CD38 regulatory B cells (p = 0.02). However, only a raised neutrophil:lymphocyte ratio and reduced frequency of CD14 HLADR monocytes were associated with poor outcomes. We conclude that persistent critical illness results in changes to immune cell phenotype only some of which are similar to that seen in physiological ageing of the immune system.
MeSH Terms
- Adult
- Aged
- Aging
- Critical Illness
- Female
- Healthy Volunteers
- Humans
- Immunity, Cellular
- Intensive Care Units
- Leukocyte Count
- Leukocytes, Mononuclear
- Male
- Middle Aged
- Phenotype
- Telomere Homeostasis
A wealth of evidence implicates both central and peripheral immune changes as contributing to the pathogenesis of Parkinson's disease (PD). It is critical to better understand this aspect of PD given that it is a tractable target for disease-modifying therapy. Age-related changes are known to occur in the immune system (immunosenescence) and might be of particular relevance in PD given that its prevalence rises with increasing age. We therefore sought to investigate this with respect to T cell replicative senescence, a key immune component of human ageing. Peripheral blood mononuclear cells were extracted from blood samples from 41 patients with mild PD (Hoehn and Yahr stages 1-2, mean (SD) disease duration 4.3 (1.2) years) and 41 age- and gender-matched controls. Immunophenotyping was performed with flow cytometry using markers of T lymphocyte activation and senescence (CD3, CD4, CD8, HLA-DR, CD38, CD28, CCR7, CD45RA, CD57, CD31). Cytomegalovirus (CMV) serology was measured given its proposed relevance in driving T cell senescence. Markers of replicative senescence in the CD8 population were strikingly reduced in PD cases versus controls (reduced CD57 expression (p = 0.005), reduced percentage of 'late differentiated' CD57 CD28 cells (p = 0.007) and 'TEMRA' cells (p = 0.042)), whilst expression of activation markers (CD28) was increased (p = 0.005). This was not driven by differences in CMV seropositivity. No significant changes were observed in the CD4 population. This study demonstrates for the first time that the peripheral immune profile in PD is distinctly atypical for an older population, with a lack of the CD8 T cell replicative senescence which characterises normal ageing. This suggests that 'abnormal' immune ageing may contribute to the development of PD, and markers of T cell senescence warrant further investigation as potential biomarkers in this condition.
MeSH Terms
- Aged
- Aging
- Antigens, CD
- Case-Control Studies
- Cellular Senescence
- Cytomegalovirus
- Female
- Flow Cytometry
- Humans
- Immunoglobulin G
- Immunophenotyping
- Immunosenescence
- Leukocytes, Mononuclear
- Male
- Middle Aged
- Parkinson Disease
- Serology
- T-Lymphocytes
Keywords
- Immune markers
- Immunosenescence
- Parkinson’s disease
- T cells
Aging is characterized by the development of metabolic dysfunction and frailty. Recent studies show that a reduction in nicotinamide adenine dinucleotide (NAD ) is a key factor for the development of age-associated metabolic decline. We recently demonstrated that the NADase CD38 has a central role in age-related NAD decline. Here we show that a highly potent and specific thiazoloquin(az)olin(on)e CD38 inhibitor, 78c, reverses age-related NAD decline and improves several physiological and metabolic parameters of aging, including glucose tolerance, muscle function, exercise capacity, and cardiac function in mouse models of natural and accelerated aging. The physiological effects of 78c depend on tissue NAD levels and were reversed by inhibition of NAD synthesis. 78c increased NAD levels, resulting in activation of pro-longevity and health span-related factors, including sirtuins, AMPK, and PARPs. Furthermore, in animals treated with 78c we observed inhibition of pathways that negatively affect health span, such as mTOR-S6K and ERK, and attenuation of telomere-associated DNA damage, a marker of cellular aging. Together, our results detail a novel pharmacological strategy for prevention and/or reversal of age-related NAD decline and subsequent metabolic dysfunction.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Cellular Senescence
- DNA Damage
- Enzyme Inhibitors
- Glucose Intolerance
- Humans
- MAP Kinase Signaling System
- Mice
- NAD
- Physical Functional Performance
- Poly(ADP-ribose) Polymerases
- Protein Kinases
- Quinolines
- Sirtuins
- TOR Serine-Threonine Kinases
- Triazoles
Keywords
- CD38
- NAD( )
- SIRTUINS
- acetylation
- aging
- exercise capacity
- glucose
- progeroid
- skeletal muscle
Nicotinamide adenine dinucleotide (NAD ) is an essential pyridine nucleotide that serves as an essential cofactor and substrate for a number of critical cellular processes involved in oxidative phosphorylation and ATP production, DNA repair, epigenetically modulated gene expression, intracellular calcium signaling, and immunological functions. NAD depletion may occur in response to either excessive DNA damage due to free radical or ultraviolet attack, resulting in significant poly(ADP-ribose) polymerase (PARP) activation and a high turnover and subsequent depletion of NAD , and/or chronic immune activation and inflammatory cytokine production resulting in accelerated CD38 activity and decline in NAD levels. Recent studies have shown that enhancing NAD levels can profoundly reduce oxidative cell damage in catabolic tissue, including the brain. Therefore, promotion of intracellular NAD anabolism represents a promising therapeutic strategy for age-associated degenerative diseases in general, and is essential to the effective realization of multiple benefits of healthy sirtuin activity. The kynurenine pathway represents the [i]de novo[/i] NAD synthesis pathway in mammalian cells. NAD can also be produced by the NAD salvage pathway. In this review, we describe and discuss recent insights regarding the efficacy and benefits of the NAD precursors, nicotinamide (NAM), nicotinic acid (NA), nicotinamide riboside (NR), and nicotinamide mononucleotide (NMN), in attenuating NAD decline in degenerative disease states and physiological aging. Results obtained in recent years have shown that NAD precursors can play important protective roles in several diseases. However, in some cases, these precursors may vary in their ability to enhance NAD synthesis [i]via[/i] their location in the NAD anabolic pathway. Increased synthesis of NAD promotes protective cell responses, further demonstrating that NAD is a regulatory molecule associated with several biochemical pathways. In the next few years, the refinement of personalized therapy for the use of NAD precursors and improved detection methodologies allowing the administration of specific NAD precursors in the context of patients' NAD levels will lead to a better understanding of the therapeutic role of NAD precursors in human diseases.
MeSH Terms
- Aging
- Animals
- Biomarkers
- Disease Susceptibility
- Gene Expression Regulation
- Gene Expression Regulation, Enzymologic
- Humans
- Metabolic Networks and Pathways
- Molecular Targeted Therapy
- NAD
- Neurodegenerative Diseases
- Oxidation-Reduction
- Signal Transduction
Keywords
- DNA damage
- NAD
- nicotinamide
- oxidative stress
- sirtuins
Mucosal-associated invariant T (MAIT) cells, defined as CD161 TCR iVα7.2 T cells, play an important role in the innate defense against bacterial infections, and their functionality is impaired in chronic viral infections. Here, we investigated the frequency and functional role of MAIT cells in chronic hepatitis B virus (HBV) infection. The peripheral CD3 CD161 TCR iVα7.2 MAIT cells in chronic HBV-infected patients and healthy controls were phenotypically characterized based on CD57, PD-1, TIM-3, and CTLA-4, as well as HLA-DR and CD38 expression. The frequency of MAIT cells was significantly decreased among chronic HBV-infected individuals as compared to controls. Expression of CD57, PD-1, CTLA-4, as well as HLA-DR and CD38 on MAIT cells was significantly elevated in chronic HBV-infected individuals relative to controls. The percentage of T cell receptor (TCR) iVα7.2 CD161 MAIT cells did not correlate with HBV viral load but inversely with HLA-DR on CD4 T cells and MAIT cells and with CD57 on CD8 T cells suggesting that decrease of MAIT cells may not be attributed to direct infection by HBV but driven by HBV-induced chronic immune activation. The percentage and expression levels of PD-1 as well as CTLA-4 on MAIT cells inversely correlated with plasma HBV-DNA levels, which may suggest either a role for MAIT cells in the control of HBV infection or the effect of HBV replication in the liver on MAIT cell phenotype. We report that decrease of TCR iVα7.2 MAIT cells in the peripheral blood and their functions were seemingly impaired in chronic HBV-infected patients likely because of the increased expression of PD-1.
MeSH Terms
- Adult
- CD8-Positive T-Lymphocytes
- DNA, Viral
- Female
- Gene Expression Regulation
- Hepatitis B, Chronic
- Humans
- Male
- Middle Aged
- Mucous Membrane
- NK Cell Lectin-Like Receptor Subfamily B
- Programmed Cell Death 1 Receptor
- Receptors, Antigen, T-Cell, alpha-beta
Keywords
- CTLA-4
- HBV infection
- HLA-DR
- PD-1
- immune exhaustion
- immunosenescence
- mucosal-associated invariant T cells
Recent reports indicate that intracellular NAD levels decline in tissues during chronological aging, and that therapies aimed at increasing cellular NAD levels could have beneficial effects in many age-related diseases. The protein CD38 (cluster of differentiation 38) is a multifunctional enzyme that degrades NAD and modulates cellular NAD homeostasis. At the physiological level, CD38 has been implicated in the regulation of metabolism and in the pathogenesis of multiple conditions including aging, obesity, diabetes, heart disease, asthma, and inflammation. Interestingly, many of these functions are mediated by CD38 enzymatic activity. In addition, CD38 has also been identified as a cell-surface marker in hematologic cancers such as multiple myeloma, and a cytotoxic anti-CD38 antibody has been approved by the FDA for use in this disease. Although this is a remarkable development, killing CD38-positive tumor cells with cytotoxic anti-CD38 antibodies is only one of the potential pharmacological uses of targeting CD38. The present review discusses the biology of the CD38 enzyme and the current state of development of pharmacological tools aimed at CD38, and explores how these agents may represent a novel approach for treating human conditions including cancer, metabolic disease, and diseases of aging.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Antibodies
- Humans
- Molecular Targeted Therapy
- NAD
- NAD Nucleosidase
- Neoplasms
- Small Molecule Libraries
Keywords
- CD38
- NAD( )
- NADase
- aging
- antibodies
- cancer and metabolism
- sirtuins
- small molecules
Increasing evidence has indicated critical roles of nicotinamide adenine dinucleotide, oxidized form (NAD ) in various biological functions. NAD deficiency has been found in models of a number of diseases such as cerebral ischemia, myocardial ischemia, and diabetes, and in models of aging. Applications of NAD or other approaches that can restore NAD levels are highly protective in these models of diseases and aging. NAD produces its beneficial effects by targeting at multiple pathological pathways, including attenuating mitochondrial alterations, DNA damage, and oxidative stress, by modulating such enzymes as sirtuins, glyceraldehyde-3-phosphate dehydrogenase, and AP endonuclease. These findings have suggested great therapeutic and nutritional potential of NAD for diseases and senescence. Recent Advances: Approaches that can restore NAD levels are highly protective in the models of such diseases as glaucoma. The NAD deficiency in the diseases and aging results from not only poly(ADP-ribose) polymerase-1 (PARP-1) activation but also decreased nicotinamide phosphoribosyltransferase (Nampt) activity and increased CD38 activity. Significant biological effects of extracellular NAD have been found. Increasing evidence has suggested that NAD deficiency is a common central pathological factor in a number of diseases and aging. Critical Issues and Future Directions: Future studies are required for solidly establishing the concept that "NAD deficiency is a common central pathological factor in a number of disease and aging." It is also necessary to further investigate the mechanisms underlying the NAD deficiency in the diseases and aging. Preclinical and clinical studies should be conducted to determine the therapeutic potential of NAD for the diseases and aging.
MeSH Terms
- Aging
- Animals
- Brain Ischemia
- Diabetes Mellitus
- Humans
- Myocardial Ischemia
- NAD
- Signal Transduction
Keywords
- NAD
- aging
- cell death
- diseases
- tissue injury
Biological aging is associated with immune activation (IA) and declining immunity due to systemic inflammation. It is widely accepted that HIV infection causes persistent IA and premature immune senescence despite effective antiretroviral therapy and virologic suppression; however, the effects of combined HIV infection and aging are not well defined. Here, we assessed the relationship between markers of IA and inflammation during biological aging in HIV-infected and -uninfected populations. Antibody response to seasonal influenza vaccination was implemented as a measure of immune competence and relationships between IA, inflammation, and antibody responses were explored using statistical modeling appropriate for integrating high-dimensional data sets. Our results show that markers of IA, such as coexpression of HLA antigen D related (HLA-DR) and CD38 on CD4 T cells, exhibit strong associations with HIV infection but not with biological age. Certain variables that showed a strong relationship with aging, such as declining naive and CD38 CD4 and CD8 T cells, did so regardless of HIV infection. Interestingly, the variable of biological age was not identified in a predictive model as significantly impacting vaccine responses in either group, while distinct IA and inflammatory variables were closely associated with vaccine response in HIV-infected and -uninfected populations. These findings shed light on the most relevant and persistent immune defects during virological suppression with antiretroviral therapy.
MeSH Terms
- Age Factors
- Aging
- Antibodies, Viral
- Antibody Formation
- Biomarkers
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Cytokines
- HIV Infections
- HLA-DR Antigens
- Humans
- Immunity, Humoral
- Inflammation
- Influenza Vaccines
- Influenza, Human
- Lymphocyte Activation
- Nerve Tissue Proteins
Aging has a strong impact on the activity of the immune system, enhancing susceptibility to pathogens and provoking a predominant pre-inflammatory status, whereas dampening responses to vaccines in humans and mice. Here, we demonstrate a loss of marginal zone B lymphocytes (MZ, CD19 CD45R CD21 CD23 ) and a decrease of naive B cells (CD19 IgD ), whereas there is an enhancement of a CD19 CD45R innate-like B cell population (B1REL) and the so-called aged B cell compartment (ABC, CD45R CD21 CD23 CD5 CD11b ) in aged senescence-accelerated (SAMP8) mice but not in aged senescence-resistant (SAMR1) mice. These changes in aged SAMP8 mice were associated with lower IgG isotype levels, displaying low variable gene usage repertoires of the immunoglobulin heavy chain (V ) diversity, with a diminution on IgG1-memory B cells (CD11b Gr1 CD138 IgM IgD CD19 CD38 IgG1 ), an increase in T follicular helper (T , CD4 CXCR5 PD1 ) cell numbers, and an altered MOMA-1 (metallophilic macrophages) band in primary follicles. LPS-mediated IgG1 responses were impaired in the B1REL and ABC cell compartments, both in vitro and in vivo. These data demonstrate the prominent changes to different B cell populations and in structural follicle organization that occur upon aging in SAMP8 mice. These novel results raise new questions regarding the importance of the cellular distribution in the B cell layers, and their effector functions needed to mount a coordinated and effective humoral response.
MeSH Terms
- Aging
- Animals
- Antigens, CD
- B-Lymphocytes
- Cell Death
- Cell Proliferation
- Gene Expression Regulation, Developmental
- IgG Deficiency
- Immunity, Humoral
- Immunity, Innate
- Immunoglobulin D
- Immunoglobulin G
- Immunoglobulin Heavy Chains
- Immunoglobulin M
- Immunologic Memory
- Lipopolysaccharides
- Mice, Inbred C57BL
- Mice, Transgenic
- Primary Cell Culture
- Signal Transduction
- Spleen
- T-Lymphocytes, Helper-Inducer
Immunosenescence is a hallmark of the aging immune system and is considered the main cause of a reduced vaccine efficacy in the elderly. Although γδ T cells can become activated by recombinant influenza hemagglutinin, their age-related immunocompetence during a virus-induced immune response has so far not been investigated. In this study we evaluate the kinetics of γδ T cells after vaccination with the trivalent 2011/2012 northern hemisphere seasonal influenza vaccine. We applied multi-parametric flow cytometry to a cohort of 21 young (19-30 years) and 23 elderly (53-67 years) healthy individuals. Activated and proliferating γδ T cells, as identified by CD38 and Ki67 expression, were quantified on the days 0, 3, 7, 10, 14, 17, and 21. We observed a significantly lower number of activated and proliferating γδ T cells at baseline and following vaccination in elderly as compared to young individuals. The kinetics changes of activated γδ T cells were much stronger in the young, while corresponding changes in the elderly occurred slower. In addition, we observed an association between day 21 HAI titers of influenza A and the frequencies of Ki67 γδ T cells at day 7 in the young. In conclusion, aging induces alterations of the γδ T cell response that might have negative implications for vaccination efficacy.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Adult
- Aged
- Aging
- Female
- Humans
- Influenza Vaccines
- Influenza, Human
- Ki-67 Antigen
- Kinetics
- Male
- Middle Aged
- T-Lymphocytes
- Young Adult
Life as we know it cannot exist without the nucleotide nicotinamide adenine dinucleotide (NAD). From the simplest organism, such as bacteria, to the most complex multicellular organisms, NAD is a key cellular component. NAD is extremely abundant in most living cells and has traditionally been described to be a cofactor in electron transfer during oxidation-reduction reactions. In addition to participating in these reactions, NAD has also been shown to play a key role in cell signaling, regulating several pathways from intracellular calcium transients to the epigenetic status of chromatin. Thus, NAD is a molecule that provides an important link between signaling and metabolism, and serves as a key molecule in cellular metabolic sensoring pathways. Importantly, it has now been clearly demonstrated that cellular NAD levels decline during chronological aging. This decline appears to play a crucial role in the development of metabolic dysfunction and age-related diseases. In this review we will discuss the molecular mechanisms responsible for the decrease in NAD levels during aging. Since other reviews on this subject have been recently published, we will concentrate on presenting a critical appraisal of the current status of the literature and will highlight some controversial topics in the field. In particular, we will discuss the potential role of the NADase CD38 as a driver of age-related NAD decline.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Armadillo Domain Proteins
- Caloric Restriction
- Cyclic ADP-Ribose
- Cytoskeletal Proteins
- Humans
- Membrane Glycoproteins
- Mitochondria
- NAD
- NADP
- Oxidation-Reduction
- Poly(ADP-ribose) Polymerases
- Protein Processing, Post-Translational
- Signal Transduction
- Sirtuins
Keywords
- Aging
- CD38
- Mitochondrial function
- NAD( )
- PARP
- SIRTUINS
Despite extensive insights on the interaction between hematopoietic stem cells (HSCs) and the supporting bone marrow (BM) stroma in hematopoietic homeostasis there remains unanswered questions on HSC regulation. We report on the mechanism by which HSCs attain cycling quiescence by addressing a role for inducible cyclic AMP early repressor (ICER). ICER negatively transcriptional regulators of cAMP activators such as CREM and CREB. These activators can be induced by hematopoietic stimulators such as cytokines. We isolated subsets of hematopoietic cells from ten healthy donors: CD34 CD38 /c-kit (primitive progenitor), CD34 CD38 /c-kit (mature progenitor) and CD34 CD38 /c-kit (differentiated lineage-). The relative maturity of the progenitors were verified in long-term culture initiating assay. Immunoprecipitation indicated the highest level of ICER in the nuclear extracts of CD34 /CD38 cells. Phospho (p)-CREM was also present suggesting a balance between ICER and p-CREM in HSC. ICER seems to be responsible for decrease in G1 transition, based on reduced Cdk4 protein, decreased proliferation and functional studies with propidium iodide. There were no marked changes in the cycling inhibitors, p15 and p-Rb, suggesting that ICER may act independently of other cycling inhibitors. The major effects of ICER were validated with BM mononuclear cells (BMNCs) in which ICER was ectopically expressed, and with BMNCs resistant to 5-fluorouracil- or cyclophosphamide. In total, this study ascribes a novel role for ICER in G1 checkpoint regulation in HSCs. These findings are relevant to gene therapy that require engineering of HSCs, age-related disorders that are associated with hematopoietic dysfunction and other hematological disorders.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Antigens, CD34
- Blotting, Western
- Cell Cycle
- Cell Differentiation
- Cells, Cultured
- Cyclic AMP Response Element Modulator
- Cyclophosphamide
- Fluorouracil
- Gene Expression
- Hematopoietic Stem Cells
- Humans
- Immunosuppressive Agents
- Proto-Oncogene Proteins c-kit
- Signal Transduction
Keywords
- Bone marrow
- Cell cycle
- Cytokines
- Hematopoietic stem cell
- Inducible cAMP early repressor
- Transcription factors
NAD( ) is required not only for life but for a long life. In this issue, Camacho-Pereira et al. (2016) implicate CD38 in the decline of NAD( ) during aging, with implications for combating age-related diseases.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Mice
- Mitochondria
- Models, Biological
- NAD
Nicotinamide adenine dinucleotide (NAD) levels decrease during aging and are involved in age-related metabolic decline. To date, the mechanism responsible for the age-related reduction in NAD has not been elucidated. Here we demonstrate that expression and activity of the NADase CD38 increase with aging and that CD38 is required for the age-related NAD decline and mitochondrial dysfunction via a pathway mediated at least in part by regulation of SIRT3 activity. We also identified CD38 as the main enzyme involved in the degradation of the NAD precursor nicotinamide mononucleotide (NMN) in vivo, indicating that CD38 has a key role in the modulation of NAD-replacement therapy for aging and metabolic diseases.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Diet, High-Fat
- Mammals
- Mice, Inbred C57BL
- Mice, Knockout
- Mitochondria
- NAD
- NAD Nucleosidase
- Niacinamide
- Organ Specificity
- RNA, Messenger
- Sirtuin 3
Keywords
- CD38
- NAD( )
- aging
- glucose intolerance
- mitochondrial function
Many treatment complications that occur late in childhood cancer survivors resemble age-related comorbidities observed in the elderly. An immune phenotype characterized by increased immune activation, systemic inflammation, and accumulation of late-differentiated memory CD57( ) CD28(-) T cells has been associated with comorbidities in the elderly. Here, we explored if this phenotype was present in young adult leukemia survivors following an average of 19 years from chemotherapy and/or radiotherapy completion, and compared this with that in age-matched controls. We found that markers of systemic inflammation-IL-6 and human C-reactive protein and immune activation-CD38 and HLA-DR on T cells, soluble CD (sCD)163 from monocytes and macrophages-were increased in survivors compared to controls. T-cell responses specific to cytomegalovirus (CMV) were also increased in survivors compared to controls while CMV IgG levels in survivors were comparable to levels measured in the elderly (>50years) and correlated with IL-6, human C-reactive protein, sCD163, and CD57( ) CD28(-) memory T cells. Immune activation and inflammation markers correlated poorly with prior chemotherapy and radiotherapy exposure. These data suggest that CMV infection/reactivation is strongly correlated with the immunological phenotype seen in young childhood leukemia survivors and these changes may be associated with the early onset of age-related comorbidities in this group.
MeSH Terms
- Adolescent
- Adult
- Age Factors
- Aged
- Antibodies, Viral
- Biomarkers
- Case-Control Studies
- Cytomegalovirus
- Cytomegalovirus Infections
- Female
- Humans
- Immunity
- Immunocompromised Host
- Immunoglobulin G
- Inflammation
- Leukemia
- Lymphocyte Activation
- Male
- Middle Aged
- Odds Ratio
- Risk Factors
- Survivors
- T-Lymphocyte Subsets
- Young Adult
Keywords
- Childhood cancer survivors
- Cytomegalovirus
- Immune activation
- Immunologic aging
- Systemic inflammation
Aging is a major risk factor for several conditions including neurodegenerative, cardiovascular diseases and cancer. Functional impairments in cellular pathways controlling genomic stability, and immune control have been identified. Biomarker of immune senescence is needed to improve vaccine response and to develop therapy to improve immune control. To identify phenotypic signature of circulating immune cells with aging, we enrolled 1068 Chinese healthy volunteers ranging from 18 to 80 years old. The decreased naïve CD4 and CD8 T cells, increased memory CD4 or CD8 T cells, loss of CD28 expression on T cells and reverse trend of CD38 and HLA-DR, were significant for aging of immune system. Conversely, the absolute counts and percentage of NK cells and CD19 B cells maintained stable in aging individuals. The Chinese reference ranges of absolute counts and percentage of peripheral lymphocyte in this study might be useful for future clinical evaluation.
MeSH Terms
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Aging
- B-Lymphocytes
- Female
- Healthy Volunteers
- Humans
- Killer Cells, Natural
- Lymphocyte Activation
- Lymphocyte Count
- Lymphocyte Subsets
- Male
- Middle Aged
- Reference Values
- Young Adult
Keywords
- aging
- flow cytometry
- lymphocyte subsets
- reference range
Mucosal-associated invariant T (MAIT) cells play an important role in innate host defence. MAIT cells appear to undergo exhaustion and are functionally weakened in chronic viral infections. However, their role in chronic hepatitis C virus (HCV) infection remains unclear. We investigated the frequency of CD8( ) CD161( ) TCR Vα7.2( ) MAIT cells in a cross-sectional cohort of chronic HCV-infected patients (n = 25) and healthy controls (n = 25). Peripheral blood mononuclear cells were investigated for circulating MAIT cell frequency, liver-homing (CCR5 and CD103), biomarkers of immune exhaustion (PD-1, TIM-3 and CTLA-4), chronic immune activation (CD38 and HLA-DR), and immunosenescence (CD57) by flow cytometry. The frequency of MAIT cells was significantly decreased, and increased signs of immune exhaustion and chronic immune activation were clearly evident on MAIT cells of HCV-infected patients. Decrease of CCR5 on circulating MAIT cells is suggestive of their peripheral loss in chronic HCV-infected patients. MAIT cells also showed significantly increased levels of HLA-DR, CD38, PD-1, TIM-3 and CTLA-4, besides CD57 in chronic HCV disease. Immune exhaustion and senescence of CD8( ) CD161( ) TCR Vα7.2( ) MAIT cells could contribute to diminished innate defence attributes likely facilitating viral persistence and HCV disease progression.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Adult
- Antigens, CD
- Biomarkers
- CD57 Antigens
- CD8-Positive T-Lymphocytes
- CTLA-4 Antigen
- Case-Control Studies
- Cohort Studies
- Cross-Sectional Studies
- Female
- Flow Cytometry
- HLA-DR Antigens
- Hepatitis A Virus Cellular Receptor 2
- Hepatitis C, Chronic
- Humans
- Immunity, Innate
- Immunosenescence
- Integrin alpha Chains
- Lymphocyte Count
- Male
- Membrane Proteins
- Middle Aged
- NK Cell Lectin-Like Receptor Subfamily B
- Programmed Cell Death 1 Receptor
- Receptors, Antigen, T-Cell, alpha-beta
- Receptors, CCR5
- Viral Load
- Young Adult
Keywords
- CD38
- HCV infection
- MAIT cells
- PD-1
- TCRVα7.2
- exhaustion
HIV infection results in damage to the gastrointestinal (GI) tract, microbial translocation and immune activation. These are not completely normalized with combined antiretroviral therapy (cART). Moreover, increate morbidity and mortality of cART-treated HIV-infected individuals is associated with inflammation. In order to enhance GI tract immunity, we recruited and treated 20 HIV-infected humans with cART supplemented with probiotics and followed inflammation and immunological parameters (clinical trial number NCT02164344). 11 HIV seronegative subjects were included as control group. The enumeration of CD4 , CD8 , CD38 and HLA-DR lymphocytes were evaluated on peripheral blood; HIV-RNA levels, sCD14, d-dimer, C-reactive protein (CRP) high sensitivity C-reactive protein (hsCRP), IL-6 and Lipopolysaccharide Binding Protein (LBP) were assayed on plasma. We observe that cART does not normalize the levels of immune activation in HIV positive patients anyway inflammation and markers of microbial translocation were significantly reduced with probiotic supplementation. Patients show a clear and statistically significant reduction in the levels of immune activation on CD4 T-lymphocytes, for both markers CD38 and HLA-DR and their simultaneous expression, LBP and hsCRP plasma levels after probiotic diet supplementation settling to values comparable to controls. Supplementing cART with probiotics in HIV-infected individuals may improve GI tract immunity and there by mitigate inflammatory sequelae, ultimately improving prognosis. ClinicalTrials.gov NCT02164344.
MeSH Terms
- Adult
- Aged
- Aging
- Anti-HIV Agents
- CD4-Positive T-Lymphocytes
- Combined Modality Therapy
- Dysbiosis
- Female
- Gastrointestinal Microbiome
- HIV Infections
- Humans
- Inflammation
- Longitudinal Studies
- Male
- Middle Aged
- Probiotics
The role of T-cell immunosenescence and functional CD8( ) T-cell responses in HIV/TB co-infection is unclear. We examined and correlated surrogate markers of HIV disease progression with immune activation, immunosenescence and differentiation using T-cell pools of HIV/TB co-infected, HIV-infected and healthy controls. Our investigations showed increased plasma viremia and reduced CD4/CD8 T-cell ratio in HIV/TB co-infected subjects relative to HIV-infected, and also a closer association with changes in the expression of CD38, a cyclic ADP ribose hydrolase and CD57, which were consistently expressed on late-senescent CD8( ) T cells. Up-regulation of CD57 and CD38 were directly proportional to lack of co-stimulatory markers on CD8( ) T cells, besides diminished expression of CD127 (IL-7Rα) on CD57( )CD4( ) T cells. Notably, intracellular IFN-γ, perforin and granzyme B levels in HIV-specific CD8( ) T cells of HIV/TB co-infected subjects were diminished. Intracellular CD57 levels in HIV gag p24-specific CD8( ) T cells were significantly increased in HIV/TB co-infection. We suggest that HIV-TB co-infection contributes to senescence associated with chronic immune activation, which could be due to functional insufficiency of CD8( ) T cells.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Adult
- CD4-CD8 Ratio
- CD57 Antigens
- CD8-Positive T-Lymphocytes
- Cell Differentiation
- Cell Proliferation
- Cellular Senescence
- Coinfection
- Disease Progression
- Female
- Granzymes
- HIV Infections
- HLA-DR alpha-Chains
- Humans
- Immunosenescence
- Interferon-gamma
- Interleukin-7 Receptor alpha Subunit
- Lymphocyte Activation
- Male
- Membrane Glycoproteins
- Perforin
- Tuberculosis, Pulmonary
Keywords
- Co-stimulation
- HIV/TB co-infection
- Immune activation
- Immunosenescence
- T-cell activation
Over the last decade, the importance of NAD( ) has expanded beyond its role as an essential cofactor for energy metabolism. NAD( ) has emerged as a major signalling molecule that serves as the sole substrate for several enzymatic reactions including the DNA repair enzyme, poly(ADP-ribose) polymerase (PARP), NAD-dependent protein deacetylases or CD38, and transcriptional factors by a new class of histone deacetylases known as sirtuins. NAD( ) levels are regulated by the metabolic status and cellular stress caused by oxidative stress and DNA damage. Since a detailed study of NAD( ) metabolism in the healthy ageing mammalian brain is nascent, we examined the effect of ageing on intracellular NAD( ) metabolism in different brain regions in female Wistar rats in young (3 months), middle aged (12 months) and older adults (24 months). Our results are the first to show a significant decline in intracellular NAD( ) levels and NAD:NADH ratio with ageing in the CNS, occurring in parallel to an increase in lipid peroxidation and protein oxidation (o- and m-tyrosine) and a decline in total antioxidant capacity. Hyperphosphorylation of H2AX levels was also observed together with increased PARP-1 and PARP-2 expression, and CD38 activity, concomitantly with reduced NAD( ) and ATP levels and SIRT1 function in the cortex, brainstem, hippocampus and cerebellum. Reduced activity of mitochondrial complex I-IV and impaired maximum mitochondrial respiration rate were also observed in the ageing rat brain. Among the multiple physiological pathways associated with NAD( ) catabolism, our discovery of CD38 as the major regulator of cellular NAD( ) levels in rat neurons indicates that CD38 is a promising therapeutic target for the treatment of age-related neurodegenerative diseases.
MeSH Terms
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Adenosine Diphosphate Ribose
- Adenosine Triphosphate
- Aging
- Animals
- Brain
- DNA Damage
- Electron Transport
- Female
- Gene Knockdown Techniques
- Lipid Peroxidation
- Membrane Glycoproteins
- Mitochondria
- NAD
- Oxidative Stress
- Poly(ADP-ribose) Polymerases
- Protein Carbonylation
- RNA, Small Interfering
- Rats
- Rats, Wistar
- Sirtuin 1
- Tissue Distribution
Clinical evaluation of immune reconstitution and health status during HIV-1 infection and anti-retroviral therapy (ART) is largely based on CD4 T cell counts and viral load, measures that fail to take into account the CD8 T cell subset, known to show features of accelerated aging in HIV disease. Here, we compare adenosine deaminase (ADA), glucose uptake receptor 1 (GLUT1), and leucine-rich repeat neuronal 3 (LRRN3) to CD38 expression and telomerase activity, two strong predictors of HIV disease progression. Our analysis revealed that reduced ADA, telomerase activity and LRRN3 gene expression were significantly associated with high CD38 and HLA-DR in CD8 T cells, with % ADA cells being the most robust predictor of CD8 T cell activation. Our results suggest that ADA, LRRN3 and telomerase activity in CD8 T cells may serve as novel, clinically relevant biomarkers of immune status in HIV-1 infection, specifically by demonstrating the degree to which CD8 T cells have progressed to the end stage of replicative senescence. Since chronological aging itself leads to the accumulation of senescent CD8 T cells, the prolonged survival and resultant increased age of the HIV population may synergize with the chronic immune activation to exacerbate both immune decline and age-associated pathologies. The identification and future validation of these new biomarkers may lead to fresh immune-based HIV treatments.
MeSH Terms
- Aging
- Base Sequence
- Biomarkers
- CD8-Positive T-Lymphocytes
- Cellular Senescence
- DNA Primers
- Flow Cytometry
- HIV Infections
- Humans
- Middle Aged
- Real-Time Polymerase Chain Reaction
Chronic inflammation in older individuals is thought to contribute to inflammatory, age-related diseases. Human monocytes are comprised of three subsets (classical, intermediate and nonclassical subsets), and despite being critical regulators of inflammation, the effect of age on the functionality of monocyte subsets remains to be fully defined. In a cross-sectional study involving 91 healthy male (aged 20-84 years, median 52.4) and 55 female (aged 20-82 years, median 48.3) individuals, we found age was associated with an increased proportion of intermediate and nonclassical monocytes (P = 0.002 and 0.04, respectively) and altered phenotype of specific monocyte subsets (e.g. increased expression of CD11b and decreased expression of CD38, CD62L and CD115). Plasma levels of the innate immune activation markers CXCL10, neopterin (P < 0.001 for both) and sCD163 (P = 0.003) were significantly increased with age. Whilst similar age-related changes were observed in both sexes, monocytes from women were phenotypically different to men [e.g. lower proportion of nonclassical monocytes (P = 0.002) and higher CD115 and CD62L but lower CD38 expression] and women exhibited higher levels of CXCL10 (P = 0.012) and sCD163 (P < 0.001) but lower sCD14 levels (P < 0.001). Monocytes from older individuals exhibit impaired phagocytosis (P < 0.05) but contain shortened telomeres (P < 0.001) and significantly higher intracellular levels of TNF both at baseline and following TLR4 stimulation (P < 0.05 for both), suggesting a dysregulation of monocyte function in the aged. These data show that aging is associated with chronic innate immune activation and significant changes in monocyte function, which may have implications for the development of age-related diseases.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Chronic Disease
- Female
- Humans
- Immunity, Innate
- Inflammation
- Male
- Middle Aged
- Monocytes
- Phenotype
- Young Adult
Generation of B and plasma cells involves several organs with a necessary cell trafficking between them. A detailed phenotypic characterization of four circulating B-cell subsets (immature-, naïve-, memory- B-lymphocytes and plasma cells) of 106 healthy adults was realized by multiparametric flow cytometry. We show that CD10, CD27 and CD38 is the minimal combination of subsetting markers allowing unequivocal identification of immature (CD10( )CD27(-)CD38( ), 6 /-6 cells/microL), naïve (CD10(-)CD27(-)CD38(-), 125 /-90 cells/microL), memory B lymphocytes (CD10(-)CD27( )CD38(-), 58 /-42 cells/microL), and plasma cells (CD10(-)CD27( )CD38( ), 2.1 /-2.1 cells/microL) within circulating CD19( ) cells. From these four subsets, only memory B lymphocytes and plasma cells decreased with age, both in relative and absolute counts. Circulating plasma cells split into CD138(-) (57 /-12%) and CD138( ) (43 /-12%) cells, the latter displaying a more mature phenotypic profile: absence of surface immunoglobulin, lower CD45 positivity and higher amounts of cytoplasmic immunoglobulin, CD38 and CD27. Unlike B lymphocytes, both populations of plasma cells are KI-67( ) and show weak CXCR4 expression.
MeSH Terms
- Adult
- Age Factors
- Aged
- Aged, 80 and over
- Aging
- B-Lymphocyte Subsets
- Female
- Flow Cytometry
- Humans
- Immunophenotyping
- Lymphocyte Count
- Male
- Middle Aged
- Plasma Cells
- Syndecan-1
- Young Adult
The aims of this flow cytometry study were to quantify B lymphoid precursors known as hématogones across age and clinical conditions and to study the immunophenotypic profile of these benign immature B cells. A total of 406 consecutive marrow specimens were analyzed for hématogones using 4-color flow cytometry during a 19 month period (60% males and 40% females). The age range was 3 months to 89 years. Hématogones were present in 80% of the specimens. Morphologic analysis of the smears from each patient showed small numbers of hématogones (<13% of total cellularity). The B cell population was defined by CD19 CD45 bright positivity, coexpression of other B lineage markers: CD20, CD22, CD10, CD29, CD38 and CD58 in addition to HLA-DR and CD34. In our study we found a significant decline in hématogones with increasing age but a broad range was found at all ages. Marrow from some adults contained relatively high numbers. Diagnosis in these patients included cytopenias, infections, and neoplastic diseases. Distinction of hématogones is critical for disease management particularly after therapy of paediatric B acute lymphoblastic leukaemia to monitor for minimal residual disease.
MeSH Terms
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Child
- Child, Preschool
- Female
- Flow Cytometry
- Humans
- Immunophenotyping
- Infant
- Male
- Middle Aged
- Precursor Cells, B-Lymphoid
- Prospective Studies
- Young Adult
Phenotypical changes in the human bone marrow (BM) due to age and stress have not so far been properly addressed in the literature. In the present study, we compared CD34( ) BM cells between older and young volunteers. The influence of stress on CD34( ) cell phenotype in older patients was investigated in an age-matched group with acute myocardial infarction (AMI). Cytokines thought to influence BM CD34( ) cell homeostasis were also analysed. BM mononuclear cells of 10 older volunteers and of 7 young volunteers (18-25 years), as well as 22 AMI patients, were analysed by flow cytometry for the following markers: CD34, CD38, CD117 (c-kit) and CD133. Blood samples were analysed for CRP, IL-6, MCP-1, IL-8, MMP-9, TIMP-1 and TNFalpha by ELISA methods. Significantly higher numbers of CD34( ) CD38(-) cells (both absolute and relative) were observed in older volunteers than in young volunteers and AMI patients. Higher numbers of immature progenitors, namely CD34( )CD38(-) cells and CD34( )CD38(-)CD117( )CD133( ) cells, were observed among older volunteers compared to the other groups. However, the relative number of CD34( ) cells lacking CD38 expression or expressing CD133 was higher in the old volunteers and AMI patients. None of the circulating factors investigated correlated with any of the cell population yields. In this study, we found that the absolute and relative numbers of BM CD34( )CD38(-) progenitor cells increase with age. The increment is attenuated in patients with AMI.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Acute-Phase Proteins
- Adolescent
- Adult
- Age Distribution
- Aged
- Aging
- Antigens, CD34
- Bone Marrow Cells
- C-Reactive Protein
- Cell Count
- Cytokines
- Female
- Flow Cytometry
- Humans
- Male
- Middle Aged
- Myocardial Infarction
- Phenotype
- Stress, Physiological
The SIRT 1 enzyme is a NAD dependent deacetylase implicated in ageing, cell protection, and energy metabolism in mammalian cells. How the endogenous activity of SIRT 1 is modulated is not known. The enzyme CD38 is a multifunctional enzyme capable of synthesis of the second messenger, cADPR, NAADP, and ADPR. However, the major enzymatic activity of CD38 is the hydrolysis of NAD. Of particular interest is the fact that CD38 is present on the inner nuclear membrane. Here, we investigate the modulation of the SIRT 1 activity by CD38. We propose that by modulating availability of NAD to the SIRT1 enzyme, CD38 may regulate SIRT1 enzymatic activity. We observed that in CD38 knockout mice, tissue levels of NAD are significantly increased. We also observed that incubation of purified recombinant SIRT1 enzyme with CD38 or nuclear extracts of wild-type mice led to a significant inhibition of its activity. In contrast, incubation of SIRT1 with cellular extract from CD38 knockout mice was without effect. Furthermore, the endogenous activity of SIRT1 was several time higher in nuclear extracts from CD38 knockout mice when compared to wild-type nuclear extracts. Finally, the in vivo deacetylation of the SIRT1 substrate P53 is increased in CD38 knockout mice tissue. Our data support the novel concept that nuclear CD38 is a major regulator of cellular/nuclear NAD level, and SIRT1 activity. These findings have strong implications for understanding the basic mechanisms that modulate intracellular NAD levels, energy homeostasis, as well as ageing and cellular protection modulated by the SIRT enzymes.
MeSH Terms
- ADP-ribosyl Cyclase 1
- Acetylation
- Aging
- Animals
- Calcium
- Cell Nucleus
- Gene Expression Regulation
- Homeostasis
- Liver
- Mice
- Mice, Knockout
- NAD
- Nuclear Envelope
- Recombinant Proteins
- Sirtuin 1
- Sirtuins
Common variable immunodeficiency (CVID) is primary hypogammaglobulinaemia with an unknown aetiopathogenesis. Although various abnormalities of T and B cells have been described, their pathogenetic roles are unclear. We determined T and B lymphocyte subsets known to be abnormal in CVID in order to disclose possible relations between numerical abnormalities in those cells. Markers associated with B cell development (CD21, CD27, IgM, IgD) were determined on B lymphocytes (CD19 ); T lymphocyte development (CD45RA, CD45RO, CD62L) and activation markers (CD25, CD27, CD28, CD29, CD38, CD57, HLA-DR) were determined on CD4 and CD8 T lymphocytes in 42 CVID patients and in 33 healthy controls. Abnormalities in CD4 T lymphocyte activation markers (increase in CD29, HLA-DR, CD45RO, decrease in CD27, CD62L, CD45RA) were observed particularly in patients with a decreased number of memory (CD27 ) and mature (CD21 ) B cells (group Ia according to the Freiburg group's classification), while abnormalities observed in CD8 cells (increase in CD27 and CD28 and decrease in HLA-DR, CD57 and CD38) did not depend upon grouping patients together according to B lymphocyte developmental subpopulations. We observed correlations between immature B cells (IgM CD21-) and expression of CD27, CD62L, CD45RA, CD45RO and HLA-DR on CD4 T cells in CVID patients but not in the control group. The expression of CD27 and CD45RA on CD4 T lymphocytes, such as the percentage of IgD CD27- and IgD CD27 cells in B lymphocytes, showed age dependency to be more significant than in the control group. Our study demonstrates that T and B lymphocyte abnormalities in CVID are partially related to each other. Some of those abnormalities are not definite, but may evolve with age of the patient.
MeSH Terms
- Adult
- Aging
- Antigens, CD
- Antigens, Differentiation, B-Lymphocyte
- Antigens, Differentiation, T-Lymphocyte
- B-Lymphocyte Subsets
- B-Lymphocytes
- Biomarkers
- CD4-Positive T-Lymphocytes
- CD8-Positive T-Lymphocytes
- Common Variable Immunodeficiency
- Female
- Flow Cytometry
- Humans
- Immunoglobulin D
- Immunoglobulin M
- Lymphocyte Activation
- Male
- Middle Aged
- T-Lymphocytes
cADPR (cADP-ribose), a metabolite of NAD , is known to modulate intracellular calcium levels and to be involved in calcium-dependent processes, including synaptic transmission, plasticity and neuronal excitability. However, the enzyme that is responsible for producing cADPR in the cytoplasm of neural cells, and particularly at the synaptic terminals of neurons, remains unknown. In the present study, we show that endogenous concentrations of cADPR are much higher in embryonic and neonate mouse brain compared with the adult tissue. We also demonstrate, by comparing wild-type and Cd38-/- tissues, that brain cADPR content is independent of the presence of CD38 (the best characterized mammalian ADP-ribosyl cyclase) not only in adult but also in developing tissues. We show that Cd38-/- synaptosome preparations contain high ADP-ribosyl cyclase activities, which are more important in neonates than in adults, in line with the levels of endogenous cyclic nucleotide. By using an HPLC method and adapting the cycling assay developed initially to study endogenous cADPR, we accurately examined the properties of the synaptosomal ADP-ribosyl cyclase. This intracellular enzyme has an estimated K(m) for NAD of 21 microM, a broad optimal pH at 6.0-7.0, and the concentration of free calcium has no major effect on its cADPR production. It binds NGD (nicotinamide-guanine dinucleotide), which inhibits its NAD -metabolizing activities (K(i)=24 microM), despite its incapacity to cyclize this analogue. Interestingly, it is fully inhibited by low (micromolar) concentrations of zinc. We propose that this novel mammalian ADP-ribosyl cyclase regulates the production of cADPR and therefore calcium levels within brain synaptic terminals. In addition, this enzyme might be a potential target of neurotoxic Zn2 .
MeSH Terms
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Animals, Newborn
- Brain
- Cyclic ADP-Ribose
- Guanine Nucleotides
- Hydrogen-Ion Concentration
- Kinetics
- Mice
- Mice, Knockout
- NAD
- Synaptosomes
- Zinc
To investigate age-related alterations in human humoral immunity, we analyzed the quantity and quality of peripheral B cell subsets, CD27-negative (CD27(-)) and CD27-positive (CD27( )) B cells, by flow cytometry analysis in 54 aged individuals (mean age /- SE, 74.6 /- 0.7 years) and 30 young individuals (mean age /- SE, 26.1 /- 0.5 years). CD27(-) and CD27( ) B cells are regarded as naive and memory B cells, respectively. CD38, Ki-67, CD95 and bcl-2 were used as activation, proliferation and apoptotic markers. Susceptibility to apoptosis was evaluated by cell size and annexin-V binding in culture cells. The percentage of CD27( ) B cells was significantly lower in aged (mean, 19.2%) individuals than that in young individuals (mean, 28.2%). The opposite was true for CD27(-) B cells (mean, 80.8% in aged and 71.8% in young) (P < 0.01). The absolute number of CD27( ) B cells in aged individuals was significantly less than the number of CD27(-) B cells. The CD27( ) B cells from aged individuals showed little susceptibility to apoptosis, although CD95 expression on the CD27( ) B cells was significantly higher in the aged individuals than in the young individuals (P < 0.05). The CD38 and bcl-2 expression on the CD27(-) B cells was significantly higher in the aged individuals than in the young individuals (P < 0.05). In addition, the CD27(-) B cells from the aged individuals showed a decreased susceptibility to apoptosis compared with that of the young individuals. These findings suggested that human aging leads to both quantitative and qualitative alterations in the peripheral B cell developmental system, including memory and naive B cell balance and their surface phenotypes.
MeSH Terms
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Adult
- Aged
- Aged, 80 and over
- Aging
- Antigens, CD
- Apoptosis
- B-Lymphocytes
- Cell Differentiation
- Female
- Humans
- Immunologic Memory
- Male
- Membrane Glycoproteins
- Proto-Oncogene Proteins c-bcl-2
- Tumor Necrosis Factor Receptor Superfamily, Member 7
- fas Receptor
To obtain more insight into blood lymphocyte subpopulations of Ethiopians, we studied the immunologic profile of children and neonates and compared these data with those obtained from adults. Peripheral blood mononuclear cells (PBMCs) and cord blood mononuclear cells (CBMCs) were collected from 137 HIV-1-uninfected subjects aged 0 (cord blood) up to 40 years. Lymphocyte subsets (T, B, and NK cells, CD4 and CD8 T cells) were determined and T cell activation (CD38 and HLA-DR) and differentiation (CD45RO and CD27) markers were measured on CD4 and CD8 T cells. The absolute number and percentage values of most lymphocyte subpopulations differed substantially with age. Neonates and children were found to have significantly higher CD4 T cell counts compared to adults. The median absolute CD4 count at birth was comparable to those reported for Caucasians. At birth 97% of the CD4 T cells were naîve and this proportion significantly declined to 14.2% during adulthood. In addition, activation of both CD4 and CD8 T cells, as determined by the double expression of HLA-DR and CD38, was observed in children under the age of 16 and adults, but not in neonates. A more differentiated phenotype (CD27-) was observed in adults compared to children for both CD4 and CD8 T cells. The immune alterations including the remarkably low CD4 count with highly depleted naîve phenotype and a persistently activated immune system seen in adult Ethiopians are not apparent at birth, but rather develop over time.
MeSH Terms
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Adolescent
- Adult
- Aging
- Antigens, CD
- B-Lymphocytes
- CD3 Complex
- CD4-CD8 Ratio
- CD4-Positive T-Lymphocytes
- CD56 Antigen
- CD8-Positive T-Lymphocytes
- Child
- Child, Preschool
- Cohort Studies
- Ethiopia
- Flow Cytometry
- HLA-DR Antigens
- Humans
- Immunophenotyping
- Infant, Newborn
- Killer Cells, Natural
- Leukocyte Count
- Lymphocyte Activation
- Lymphocyte Subsets
- Membrane Glycoproteins
- Receptors, IgG
Systemic and mucosal humoral immune responses have been reported to exhibit an age related decline. However, differences in primary and memory responses at mucosal sites in aged mice have been noted. In an effort to begin characterizing deficiencies in the mucosal system of aged mice, we examined the B cell compartment of gut associated Peyer's patch lymphoid tissue. To our surprise, we found that germinal center (GC) B cells from aged B6D2F1 mice (24-26 months) were present at similar frequencies and exhibited a normal activation phenotype such as upregulation of B7.1, B7.2 and CD44, and downregulation of CD23, CD62L and CD38 as that observed in younger mice (2.5-4 months). As expected, Peyer's patch GC B cells from aged mice expressing V(H)X24 genes displayed higher somatic mutation frequencies compared with younger mice. However, this was particularly striking in IgM sequences where high mutational loads suggested we were sampling memory cells. It is conceivable that B-cells expressing these genes reflect the presence of a mucosal memory compartment in aged mice that either retains flexibility in effector function or is committed to the secretion of IgM antibody.
MeSH Terms
- Aging
- Animals
- B-Lymphocytes
- Base Sequence
- Germinal Center
- Immunoglobulin M
- Immunoglobulin Variable Region
- Immunologic Memory
- Mice
- Mice, Inbred Strains
- Molecular Sequence Data
- Peyer's Patches
- Phenotype
- Somatic Hypermutation, Immunoglobulin
While investigators in a number of laboratories have documented that the hematopoietic stem cells (HSCs) of fetal and adult mice are CD38 , no information is available about CD38 expression by HSCs of newborn and juvenile mice. We used a murine transplantation model to examine HSC CD38 expression. First, we observed that all HSCs from newborn bone marrow are CD38-. Next, it was determined that the majority of HSCs in the bone marrow of 5-week-old mice are CD38-, with a minority being CD38 . These observations indicated that the CD38 subpopulation of HSC appears before the age of 5 weeks and expands during adolescence. However, the majority of HSCs of 5-week-old mice became CD38 following injection of 5-fluorouracil, indicating that activation of juvenile stem cells enhances CD38 expression. These observations may have implications for CD38 expression by HSCs from human umbilical cord blood and bone marrow of young children in steady state and under pathological conditions.
MeSH Terms
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Animals, Genetically Modified
- Animals, Newborn
- Antigens, CD
- Antigens, CD34
- Antigens, Ly
- Bone Marrow Transplantation
- Cell Differentiation
- Female
- Gene Expression Regulation, Developmental
- Hematopoietic Stem Cells
- Membrane Glycoproteins
- Mice
- Mice, Inbred C57BL
- Tissue Donors
- Whole-Body Irradiation
ART2.2 is a mouse T-cell surface ectoenzyme [mono (ADP-ribosyl) transferase] shed upon strong activation. We analysed temporal changes in ART2.2 expression in unmanipulated and cyclophosphamide-treated NOD/Lt mice compared with diabetes-resistant control strains. We used NAD, the ART2.2 substrate, to test whether ART-mediated ADP-ribosylation could retard diabetogenic activation of islet-reactive T cells in vitro. ART2.2 and CD38, another NAD-utilizing enzyme, were measured by flow cytometry. ADP-ribosylation from ethano-NAD was followed by flow cytometry using a reagent specific for etheno-ADP ribose. Although mature NOD CD4 and C D8 T cells expressed ART2.2, this expression was delayed in young NOD mice when compared with control strains. This ontological delay at 3 weeks of age correlated with an early burst of CD25 expression unique to NOD splenic T cells. This pattern was reproduced in cyclophosphamide-accelerated diabetes in young NOD/Lt males, wherein a retarded repopulation of ART2.2 T cells in spleen and islets correlated with development of heavy insulitis and diabetes. NAD inhibited anti-CD3 induced activation of splenic T cells in vitro and also retarded killing of beta-cell targets by NOD islet-reactive CD8 effectors in vitro at concentrations equal to or greater than 1 micromol/l. Evidence suggested that CD38 on B lymphocytes competes with ART2.2 for substrate needed by B lymphocytes for ADP ribosylation. ART2.2 on T cells may not simply mark the resting state, but could also contribute to it via ADP-ribosylation.
MeSH Terms
- ADP Ribose Transferases
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Antigens, CD
- Antigens, Differentiation
- Cell Membrane
- Cyclophosphamide
- Diabetes Mellitus, Type 1
- Flow Cytometry
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Enzymologic
- Gene Rearrangement, T-Lymphocyte
- Islets of Langerhans
- Lymphocyte Activation
- Male
- Membrane Glycoproteins
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Inbred NOD
- Mice, Inbred Strains
- Mice, Transgenic
- NAD Nucleosidase
- Spleen
- T-Lymphocytes
Analysis of expression of CD38, CD45R (B220), IgM and IgD on splenic B lymphocytes from mice of different ages demonstrated CD38 on both immature (B220( ), BCR(-)) and mature (B220( ), BCR( )) B lymphocytes. Similarly, CD38 is expressed as early as B220 on the surface of progenitor B cells in the bone marrow. In spite of expressing of CD38 and IgM, neonatal B cells, in contrast to the adult, failed to proliferate to either anti-CD38 or anti-IgM cross-linking when IL-4 was present. They did, however, respond to LPS and anti-CD40, and by 2 weeks of age they began to respond to anti-CD38 and anti-IgM, reaching adult B cell levels by 4 weeks. Although the distribution of CD38 on adult B cells from most different lymphoid compartments was broadly similar, significantly higher levels of CD38 were expressed on peritoneal B lymphocytes. A detailed analysis, using IgM / IgD ratio and staining with anti-CD5 confirmed that B1 lymphocytes were expressing a high level of CD38. Interestingly, both immature B cells and peritoneal B1 lymphocytes were unresponsive to anti-CD38. However, they were activated by LPS or anti-CD40.
MeSH Terms
- ADP-ribosyl Cyclase
- ADP-ribosyl Cyclase 1
- Aging
- Animals
- Antibodies
- Antigens, CD
- Antigens, Differentiation
- B-Lymphocytes
- Bone Marrow Cells
- CD40 Antigens
- Cell Differentiation
- Cell Division
- Female
- Flow Cytometry
- Immunoglobulin D
- Immunoglobulin M
- Lipopolysaccharides
- Lymphocyte Activation
- Membrane Glycoproteins
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- NAD Nucleosidase
- Peritoneal Cavity
- Peyer's Patches
- Receptor Aggregation
- Spleen
- Stem Cells
Autologous peripheral blood progenitor cell (PBPC) transplantation is now commonly used in children. The ontogenic differences in haematopoiesis published in recent years suggest differences in the categories of mobilized PBPCs between children and adults. We investigated the frequency and distribution of mature progenitor cells (colony-forming cells, CFCs) and primitive progenitor cells [CD34 CD38- and CD34 Thy-1 cells, long-term culture-initiating cells (LTC-ICs)] in children and adults mobilized using granulocyte colony-stimulating factor alone. We found similar proportions of granulocyte colony-forming units (CFU-G) and/or macrophage CFUs (CFU-M), mixed lineage CFUs (CFU-Mix) and megakarocyte CFUs (CFU-Mk), CD34 CD38- and CD34 Thy-1 cells, and LTC-ICs (16.5 /- 3.5 vs. 10.65 /- 5 per 104 CD34 cells), which produced the same number of CFCs (5 /- 1 vs. 6 /- 1 CFCs/LTC-ICs) in PB CD34 cells from children and adults. However, we noted a higher proportion of erythroid blast-forming units (BFU-E) in PB CD34 cells from adults (x 1.5, P = 0.003). Using cord blood as a third ageing point, we observed an inverse age-related propensity for commitment to the monocyte/macrophage lineage that was still found after normalizing the data per body weight and processed blood mass. This ontogeny-related programming was detected from the LTC-IC level, which produced 1.7 times more CFU-M in children than in adults (P = 0.048). These subtle differences in commitment between children and adults, shown here for the first time, are of interest for the in vitro manipulation of PBPCs and, in particular, for application in adoptive immunotherapy in children.
MeSH Terms
- Adult
- Aging
- Antigens, CD34
- Cell Count
- Cell Lineage
- Child
- Erythroblasts
- Fetal Blood
- Granulocyte Colony-Stimulating Factor
- Granulocytes
- Hematopoietic Stem Cell Mobilization
- Hematopoietic Stem Cell Transplantation
- Hematopoietic Stem Cells
- Humans
- Immunotherapy, Adoptive
- Macrophages
- Monocytes
- Thy-1 Antigens
Histological investigations suggest that the size and number of lymphoid follicles of the adenoids and tonsils decrease during ageing. The mechanisms underlying the histological changes are unknown. The authors have analysed the frequency of lymphocyte subpopulations in the adenoids by flow cytometry. The proportion of B lymphocytes decreased and the proportion of T lymphocytes of all mononuclear cells increased with age. Of all B lymphocytes the proportion of CD38 , surface IgD- B lymphocytes representing the germinal centre cell phenotype, decreased and the proportion of CD38-, IgD- B lymphocytes representing the mature B lymphocyte phenotype, increased with age. The expression of CD23, a cell surface molecule associated with activation of follicular mantle IgD B lymphocytes, did not change with increasing age. The results imply that the involution of the adenoid is associated with a decreased germinal centre reaction and relative accumulation of mature B cells in the adenoidal tissue, as analysed by three-colour flow cytometry.
MeSH Terms
- Adenoids
- Adolescent
- Adult
- Aging
- B-Lymphocyte Subsets
- Child
- Child, Preschool
- Female
- Humans
- Hyperplasia
- Immunophenotyping
- Infant
- Male
- Otitis Media
- Sinusitis
- T-Lymphocyte Subsets
Ageing is associated with complex remodelling in the phenotypic and functional profiles of T lymphocytes. We investigated whether expression of CD28 antigen on T cells is conserved throughout adulthood and ageing in humans. For this purpose we analysed T cells obtained from peripheral blood of 102 healthy people of ages ranging from 20 to 105 years. We found an age-related increase of CD28- T cells in percentage and absolute number, predominantly among CD8 T cells. CD28- T cells from aged donors analysed by flow cytometry appeared as resting cells (not expressing CD25, CD38, CD69, CD71, DR), bearing markers of cytotoxic activity (CD 11b and CD 57) and with a phenotype compatible with 'memory' cells (up-regulated CD2 and CD11a; CD62L absent). At the functional level, freshly isolated purified CD28- CD8 T cells showed high anti-CD3 redirected cytotoxic activity against Fc-bearing P815 cells. The same activity tested on freshly isolated bulk T lymphocytes was significantly augmented with age. We found a positive correlation between age, number of CD8 CD28- T cells and anti-CD3 redirected cytotoxicity by freshly isolated T cells. These data suggest that an activation of unknown nature within the cytotoxic arm of the immune system occurs with age. We speculate that these cytotoxic T lymphocytes (CTL) in vivo may constitute armed effector cells for immediate killing of targets bearing peptides from pathogens of intracellular origin.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- CD28 Antigens
- CD3 Complex
- CD8-Positive T-Lymphocytes
- Cell Separation
- Cytotoxicity, Immunologic
- Flow Cytometry
- Humans
- Lymphocyte Count
- Middle Aged
A reference range for lymphocyte populations, with particular emphasis on T lymphocyte subsets, was obtained for normal individuals covering age cohorts from birth through adulthood. This report confirms and extends findings from a developmental reference range published earlier (1). Absolute numbers of WBC, lymphocytes, and T, B, and NK subsets decline significantly during childhood. However, differences in the rate of decline of certain lymphocyte subsets leads to discordance between absolute numbers and percentages. Those lymphocyte subsets which decline less rapidly with age than the total lymphocyte count will show an increase in percentage, whereas those which decline more rapidly will show further declines in percentage values. T cell percentages were seen to increase over time whereas B cell percentages decline. Markers of immaturity such as CD45RA on CD4 cells and CD38 on CD8 cells declined in both percentages and absolute numbers. Activation markers, such as HLA-DR on CD8 cells and IL2-R on CD3 cells, increased in percentages with time but changed inconsistently in cell number from infancy to adulthood. These findings extend the lymphocyte references range to markers thought to be informative in various disease states, including HIV infection.
MeSH Terms
- Adolescent
- Adult
- Aging
- Antigens, Differentiation, T-Lymphocyte
- CD4-Positive T-Lymphocytes
- CD8 Antigens
- Child
- Child, Preschool
- Female
- Humans
- Immunophenotyping
- Infant
- Infant, Newborn
- Leukocyte Common Antigens
- Leukocyte Count
- Male
- Middle Aged
- T-Lymphocyte Subsets
Immune activation is an important component of HIV disease in adults that may reflect a protective host response and/or be a component of immunopathogenesis. The goals of this study were to gain understanding of T cell activation in pediatric HIV disease, to assess the usefulness of T cell activation markers as surrogates for disease progression and/or early identification of infection in infants at risk, and to determine any advantages of three- compared to two-color flow cytometric immunophenotyping for the above assessments. We examined the expression of cell-surface activation antigens on the CD4 and CD8 T cells of 26 HIV-infected and 40 HIV-seronegative age-matched control children. Compared with controls, HIV-infected children showed a slight but not significant decrease in the proportion of CD4 cells that coexpressed CD45RA and L-selectin (mean of 83 vs 75% for < 2 years of age, 76 vs 62% for 2-3 years, 64 vs 56% for > or = 4 years). CD4 cells coexpressing CD38 and HLA-DR were significantly increased in HIV children (mean of 2 vs 6% for < 2 years of age, 3 vs 11% for 2-3 years, 2 vs 8% for > or = 4 years). There was a striking and significant increase in the proportion of CD8 cells coexpressing CD38 and HLA-DR (mean of 5 vs. 25% for < 2 years, 10 vs 41% for 2-3 years, 6 vs 31% for > or = 4 years); this double positive population of CD8 cells included cells that were approximately 1 log brighter for the expression of CD38 than for that of CD38 single-positive cells. There was a significant reduction in CD45RA CD8 cells (means of 92 vs 71% for < 2 years of age, 88 vs 50% for 2-3 years, 80 vs 57% for > or = 4 years) and an increase in CD57 CD8 cells (mean of 4 vs 8% for < 2 years of age, 8 vs 22% for 2-3 years, 19 vs 31% for > or = 4 years) in HIV children. The inclusion of CD3 as an anchor marker for CD8 cell subsets to limit the analysis to CD3 CD8 cells did not substantially alter the data nor enhance the differences between infected and control children compared with the analysis of all CD8 cells.(ABSTRACT TRUNCATED AT 400 WORDS)
MeSH Terms
- Acquired Immunodeficiency Syndrome
- Aging
- Antigens, CD
- Antigens, Differentiation, T-Lymphocyte
- CD3 Complex
- CD4 Antigens
- CD57 Antigens
- CD8 Antigens
- Child
- Child, Preschool
- HIV Infections
- HLA-DR Antigens
- Humans
- Immunophenotyping
- Infant
- Lymphocyte Activation
- T-Lymphocyte Subsets
- T-Lymphocytes
The circulating lymphocytes of 88 consecutive patients following autologous, conventional, or T-cell depleted bone marrow transplantation were serially analyzed for B-cell surface antigen expression and function. In the majority of patients, except for those who developed chronic graft-versus-host disease, the number of circulating CD20 B cell normalized by the fourth posttransplant month. The earliest detectable B cells normally expressed HLA-DR, CD19, surface immunoglobulin (slg), CD21, Leu-8, and lacked expression of CD10 (CALLA). In addition, the circulating B cells expressed CD1c, CD38, CD5, and CD23 for the first year following transplant, antigens that are normally expressed on a small percentage of circulating B cells in normal adults, but highly expressed on cord blood B cells. Similar to cord blood B cells, patient B cells isolated during the first year following transplant, proliferated normally to Staphylococcus aureus Cowan strain I (SAC), and produced IgM, but minimal or no IgG when stimulated with pokeweed mitogen and SAC, unlike normal adult B cells that produce both. The similar phenotype and function of posttransplant and cord blood B cells, and their similar rate of decline in patients and normal children adds further evidence to support the hypothesis that B-cell differentiation posttransplant is recapitulating normal B-cell ontogeny.
MeSH Terms
- Adult
- Aging
- Antigens, CD
- Antigens, CD20
- Antigens, Differentiation, B-Lymphocyte
- B-Lymphocytes
- Bone Marrow Transplantation
- Cell Differentiation
- Child
- Child, Preschool
- Graft vs Host Disease
- HLA-DR Antigens
- Humans
- Immunoglobulin G
- Immunoglobulin M
- Immunophenotyping
- Infant, Newborn
- Leukocyte Count
- Lymphocyte Activation
- Staphylococcus aureus
- T-Lymphocytes
The role of accessory cells (AC) in the temporal expression of several key T-cell-activation-associated antigens has been studied in healthy aged subjects. Compared to responses seen in young adults, phytohaemagglutinin (PHA) induced weak proliferation in peripheral blood mononuclear cells from the aged and lower numbers of T cells expressing CD71, CD25, CD38 or HLA-DR. T cell responses to the monoclonal antibody OKT3, however, were normal. Whereas HLA-DR T cell numbers could be increased by raising the AC content (up to 50%) in cultures comprising purified T cells and graded numbers of autologous AC, CD25 T cell numbers remained largely unaltered. Co-stimulation with PHA phorbol myristate acetate in the absence of AC restored both proliferation and CD25 expression in the aged. These results indicate that T cells from the healthy aged show selective deficiencies in their capacity to respond to mitogenic stimuli and suggest that impaired PHA responsiveness is due, at least in part, to defective AC-derived signals.
MeSH Terms
- Aged
- Aged, 80 and over
- Aging
- Antigen-Presenting Cells
- Antigens, CD
- Cell Division
- Female
- HLA-DR Antigens
- Humans
- Interleukin-2
- Lymphocyte Activation
- Male
- Monocytes
- Muromonab-CD3
- Phytohemagglutinins
- T-Lymphocyte Subsets
- Tetradecanoylphorbol Acetate