CD24
Signal transducer CD24 precursor (Small cell lung carcinoma cluster 4 antigen) (CD24 antigen) [CD24A]
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Identification of specific cell markers is crucial for recognizing functionally healthy nucleus pulposus (NP) cells. The objective of this study was to investigate the role of CD24 expression in adult human NP cells. Cells were retrieved from NP tissues of 20 patients (aged 17-44) operated on for lumbar disc herniation. Based on CD24 expression, NP cells were separated by sorting and then used to examine phenotypic behavior, the effects of culture conditions and cellular senescence pathway related proteins. CD24 expression was positive in 35.5 ± 3.7% (range 9.1-65.2%) of NP cells. Consistently, normoxic expansion and serial passages in monolayers decreased percentage positivity for CD24 in NP cells. CD24 NP cells showed a markedly decreased GSK-3β activity and increased mitogen-activated protein kinase phosphorylation accompanying by an increased β-catenin expression. Higher levels of matrix metalloproteinases, as well as lower levels of [i]ACAN[/i] and [i]COL2[/i] in CD24 cells, indicated the breakdown and reduced the formation of key extracellular matrix components. CD24 NP cells presented a more favorable phenotype while CD24 cells showed a more prominent cellular senescence fate. CD24 in NP cells may be a surrogate marker of healthy cells, in the cell-based therapeutic treatment of degenerative disc disorders.
MeSH Terms
- Adolescent
- Adult
- CD24 Antigen
- Cellular Senescence
- Female
- Fetal Proteins
- Gene Expression Regulation
- Humans
- Male
- Nucleus Pulposus
- Phenotype
- RNA, Messenger
- Receptors, Virus
- T-Box Domain Proteins
- Young Adult
Keywords
- CD24
- Nucleus pulposus
- cell therapy
- cellular senescence
- phenotype
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
Colorectal cancer (CRC) is the second leading cause of death among cancer patients in the Northern countries. CRC can reappear a long time after treatment. Recent clinical studies demonstrated that, in response to chemotherapy, cancer cells may undergo stress-induced premature senescence (SIPS), which typically results in growth arrest. Nonetheless, these senescent cells were reported to divide in an atypical manner and thus contribute to cancer re-growth. Therefore, we examined if SIPS escape may follow treatment with chemotherapeutics used clinically: 5-fluorouracil (5-FU), oxaliplatin (OXA) and irinotecan (IRINO). To mimic the therapeutic regimes we exposed human colon cancer HCT116 and SW480 cells to repeated cycles of drug treatment. The cells treated with 5-FU or IRINO exhibited several hallmarks of SIPS: growth arrest, increased size and granularity, polyploidization, augmented activity of the SA-β-galactosidase, accumulation of P21 and CYCLIN D1 proteins, and the senescence-associated secretory phenotype. Moreover, re-population of the cancer cell cultures was delayed upon treatment with the senescence-inducing agents. At the same time, we detected a subpopulation of senescent colon cancer cells with features of stemness: elevated NANOG expression, exclusion of Hoechst 33342 (typical for side population) and increased CD24 expression. Additionally, rare, polyploid cells exhibited blastocyst-like morphology and produced progeny. In parallel, majority of chemotherapeutics-treated cells underwent mesenchymal to epithelial transition, as the percentage of CD44-positve cells was reduced, and levels of E-cadherin (epithelial marker) were elevated. Our study demonstrates that a subpopulation of chemotherapeutics-treated colon cancer cells display a specific phenotype being a combination of stem-like and senescent cell features. This may contribute to their resistance to chemotherapy and their ability to re-grow cancer after completion of therapeutic intervention.
MeSH Terms
- Antineoplastic Agents
- Cellular Senescence
- Colonic Neoplasms
- Cyclin D1
- Drug Resistance, Neoplasm
- Epithelial-Mesenchymal Transition
- Fluorouracil
- HCT116 Cells
- Humans
- Hyaluronan Receptors
- Irinotecan
- Neoplastic Stem Cells
- Oxaliplatin
Keywords
- 5-fluoruracil
- angiogenesis
- cancer Biology
- cancer stem cells
- cell Cycle control
- chemotherapy
- colon cancer
- doxorubicin
- irinotecan
- molecular Therapy
- oxaliplatin
- senescence
The nucleus pulposus (NP) of the intervertebral disc (IVD) demonstrates substantial changes in cell and matrix composition with both ageing and degeneration. While recent transcriptomic profiling studies have helped define human NP cell phenotype, it remains unclear how expression of these markers is influenced by ageing or degeneration. Furthermore, cells of the NP are thought to derive from the notochord, although adult NP lacks identifiable notochordal (NC) cells. This study aimed to confirm expression of previously identified NP and NC marker genes in adult human NP cells from a range of ages and degenerate states. Importantly, using gene expression analysis (N = 60) and immunohistochemistry (N = 56) the study demonstrates expression of NP markers FoxF1, Pax-1, keratin-8/18, carbonic anhydrase-12, and NC markers brachyury, galectin-3 and CD24 in cells of the NP irrespective of age or degeneration. Our immunohistochemical data, combined with flow cytometry (N = 5) which identified a small number of CA12 Gal3 T CD24 cells, suggests the possible presence of a sub-population of cells with an NC-like phenotype in adult NP tissue. These findings suggest that the NP contains a heterogeneous population of cells, which may possess varied phenotypic and functional profiles and thus warrant further investigation to improve our understanding of IVD homeostasis and repair.
MeSH Terms
- Adolescent
- Adult
- Aging
- Biomarkers
- Humans
- Intervertebral Disc
- Intervertebral Disc Degeneration
- Middle Aged
- Notochord
- Nucleus Pulposus
- Young Adult
There is compelling evidence associating senescent cells with the malignant progression of tumours. Of all senescence-related mechanisms, the so-called senescence-associated secretory phenotype (SASP) has attracted much attention. Since the pro-inflammatory cytokines IL-6 and IL-8 are consistently present in the SASP, and secreted by highly aggressive breast cancer cell lines, we aimed at elucidating their role on the less aggressive breast cancer cell line MCF-7, which does not secret these cytokines. The MCF-7 cell line was treated with either senescence-conditioned medium (SCM), IL-6 or IL-8 and then evaluated for phenotypic (CD44 and CD24 by FACS) and functional changes associated with an EMT program (migration/invasion) and for the acquisition of stem cell properties: mammosphere-forming capacity, expression of reprogramming factors (by qRT-PCR) and multilineage differentiation potential. We also evaluated the role of IL6 and IL8 in the cytokine-secreting, highly tumorigenic cell line MDA-MB-231. Our results show that treatment of MCF-7 cells with IL6 and IL8, alone or together, induced the appearance of cells with fibroblastoid morphology, increased CD44 expression and migration, self-renewal and multilineage differentiation capacity, all characteristics compatible with an EMT program and stemness. These changes closely resembled those induced by a SCM. Interestingly, SCM treatments further increased IL6 and IL8 secretion by MCF-7 cells, thus suggesting the participation of an autocrine loop. Indeed, neutralizing antibodies against IL6 and IL8 reversed the effects of SCM on MCF-7, pinpointing these cytokines as major mediators of EMT and stemness-related effects associated with the senescent microenvironment. Additionally, prolonged exposure of MCF cells to IL6 or IL8 induced the appearance of senescent cells, suggesting a mechanism by which senescence and inflammation are reinforced favouring the acquisition of EMT and stem-like features at the population level, thus increasing tumour aggressiveness. Strikingly, our results also show that both IL6 and IL8 are important to maintain aggressive traits in MDA-MB-231 cells, a highly tumorigenic cell line, which appears to be devoid of stemness-related features. This study demonstrates that, similar to what is observed with a senescent microenvironment, purified IL6 and IL8 induce a self- and cross-reinforced senescence/inflammatory milieu responsible for the emergence of epithelial plasticity and stemness features, thus conferring more aggressive phenotypes to a luminal breast cancer cell line. On the other hand, the basal-like MDA-MB-231 cells, whose aggressiveness-related features depend on IL6 and IL8 secretion, almost completely lack mammosphere formation and differentiation capacities, suggesting that tumour aggressiveness is not always related to stemness.
MeSH Terms
- Breast Neoplasms
- Carcinogenesis
- Cellular Senescence
- Culture Media, Conditioned
- Humans
- Inflammation
- Interleukin-6
- Interleukin-8
- MCF-7 Cells
- Phenotype
Keywords
- Breast cancer
- IL6
- IL8
- Inflammation
- Senescence
- Stemness
Diseases associated with human cartilage, including rheumatoid arthritis (RA) and osteoarthritis (OA) have manifested age, mechanical stresses and inflammation as the leading risk factors. Although inflammatory processes are known to be upregulated upon aging, we sought to gain a molecular understanding of how aging affects the tissue-specific response to inflammation. In this report, we explored the role of cluster of differentiation 24 (CD24) in regulating differential inflammatory responses in juvenile and adult human chondrocytes. Differential cell-surface CD24 expression was assessed in juvenile and adult chondrocytes along with human induced pluripotent stem cell (hiPSC)-derived neonatal chondrocytes through gene expression and fluorescence-activated cell sorting (FACS) analyses. Loss of function of CD24 was achieved through silencing in chondrocytes and the effects on the response to inflammatory cues were assessed through gene expression and NFκB activity. CD24 expression in chondrocytes caused a differential response to cytokine-induced inflammation, with the CD24 juvenile chondrocytes being resistant to IL-1ß treatment as compared to CD24 adult chondrocytes. CD24 protects from inflammatory response by reducing NFκB activation, as an acute loss of CD24 via silencing led to an increase in NFκB activation. Moreover, the loss of CD24 in chondrocytes subsequently increased inflammatory and catabolic gene expression both in the absence and presence of IL-1ß. We have identified CD24 as a novel regulator of inflammatory response in cartilage that is altered during development and aging and could potentially be therapeutic in RA and OA.
MeSH Terms
- Adolescent
- Adult
- Aging
- CD24 Antigen
- Cartilage, Articular
- Cell Differentiation
- Cell Separation
- Child
- Child, Preschool
- Chondrocytes
- Female
- Fetus
- Flow Cytometry
- Gene Expression Profiling
- Humans
- Immunohistochemistry
- Infant
- Inflammation
- Male
- Pluripotent Stem Cells
- Real-Time Polymerase Chain Reaction
- Transcriptome
Keywords
- CD24
- Cartilage
- OA
- inflammation
Previous study claimed that disc degeneration may be preceded by structure and matrix changes in the intervertebral disc (IVD) which coincide with the loss of distinct notochordally derived nucleus pulposus (NP) cells. However, the fate of notochordal cells and their molecular phenotype change during aging and degeneration in human are still unknown. In this study, a set of novel molecular phenotype markers of notochordal NP cells during aging and degeneration in human IVD tissue were revealed with immunostaining and flow cytometry. Furthermore, the potential of phenotype juvenilization and matrix regeneration of IVD cells in a laminin-rich pseudo-3D culture system were evaluated at day 28 by immunostaining, Safranin O, and type II collagen staining. Immunostaining and flow cytometry demonstrated that transcriptional factor Brachyury T, neuronal-related proteins (brain abundant membrane attached signal protein 1, Basp1; Neurochondrin, Ncdn; Neuropilin, Nrp-1), CD24, and CD221 were expressed only in juvenile human NP tissue, which suggested that these proteins may be served as the notochordal NP cell markers. However, the increased expression of CD54 and CD166 with aging indicated that they might be referenced as the potential biomarker for disc degeneration. In addition, 3D culture maintained most of markers in juvenile NP, and rescued the expression of Basp1, Ncdn, and Nrp 1 that disappeared in adult NP native tissue. These findings provided new insight into molecular profile that may be used to characterize the existence of a unique notochordal NP cells during aging and degeneration in human IVD cells, which will facilitate cell-based therapy for IVD regeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1316-1326, 2016.
MeSH Terms
- Adolescent
- Adult
- Aged
- Aging
- Antigens, CD
- Biomarkers
- Child
- Collagen Type II
- Female
- Humans
- Intervertebral Disc Degeneration
- Male
- Middle Aged
- Nucleus Pulposus
- Phenotype
Keywords
- 3D culture system
- intervertebral disc
- molecular phenotype
- notochordal cells
- nucleus pulposus
CD24 is a glycophosphatidylinositol (GPI)-linked cell surface receptor that is involved in regulating the survival or differentiation of several different cell types. CD24 has been used to identify pre-adipocytes that are able to reconstitute white adipose tissue (WAT) in vivo. Moreover, we recently found that the dynamic upregulation of CD24 in vitro during early phases of adipogenesis is necessary for mature adipocyte development. To determine the role of CD24 in adipocyte development in vivo, we evaluated the development of the inguinal and interscapular subcutaneous WAT and the epididymal visceral WAT in mice with a homozygous deletion of CD24 (CD24KO). We observed a significant decrease in WAT mass of 40% to 74% in WAT mass from both visceral and subcutaneous depots in male mice, with no significant effect in female mice, compared to wild-type (WT) sex- and age-matched controls. We also found that CD24KO mice had increased fasting glucose and free fatty acids, decreased fasting insulin, and plasma leptin. No major differences were observed in the sensitivity to insulin or glucose, or in circulating triglycerides, total cholesterol, HDL-cholesterol, or LDL-cholesterol levels between WT and CD24KO mice. Challenging the CD24KO mice with either high sucrose (35%) or high fat (45%) diets that promote increased adiposity, increased WAT mass and fasting insulin, adiponectin and leptin levels, as well as reduced the sensitivity to insulin and glucose, to the levels of WT mice on the same diets. The CD24-mediated reduction in fat pad size was due to a reduction in adipocyte cell size in all depots with no significant reduction pre-adipocyte or adipocyte cell number. Thus, we have clearly demonstrated that the global absence of CD24 affects adipocyte cell size in vivo in a sex- and diet-dependent manner, as well as causing metabolic disturbances in glucose homeostasis and free fatty acid levels.
MeSH Terms
- Adipogenesis
- Adipose Tissue, White
- Aging
- Animals
- CD24 Antigen
- Diet
- Female
- Glucose Metabolism Disorders
- Lipid Metabolism Disorders
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
Salivary gland dysfunction is a major side effect of radiotherapy for head and neck cancer patients, which in the future might be salvaged by autologous adult salivary gland stem cell (SGSC) therapy. Since frail elderly patients may have decreased activity of SGSCs, we aimed to characterize the potential of aged SGSC-population in a murine model. Salivary glands and salisphere-derived cells from young and old mice were tested for CD24 and CD29 stem cell marker expression using FACS. Moreover, in vitro expansion capability and in vivo regeneration potential upon post-irradiation transplantation of young and aged SGSCs were measured. An increase in CD24(hi)/CD29(hi) putative stem cells was detected in aged salivary glands albeit with a decrease in functional ability to form salispheres. However, the salispheres formed from aged mice salivary glands expressed CD24(hi)/CD29(hi) to the same extent as the ones from young mice. Moreover, following exposure to adequate growth conditions old and young SGSCs exhibited similar in vitro expansion- and in vivo regeneration potential. Aged SGSCs although reduced in number are in vitro indistinguishable from young SGSCs and could potentially be used to ameliorate age- or treatment related salivary gland dysfunction.
MeSH Terms
- Animals
- CD24 Antigen
- Cells, Cultured
- Cellular Senescence
- Female
- Integrin beta1
- Mice
- Mice, Inbred C57BL
- Regeneration
- Salivary Glands
- Stem Cell Transplantation
- Stem Cells
Keywords
- Aging
- Radiation-xerostomia
- Regeneration
- Salivary glands
- Stem cells
Intervertebral disc (IVD) disorder and age-related degeneration are believed to contribute to low back pain. Cell-based therapies represent a promising strategy to treat disc degeneration; however, the cellular and molecular characteristics of disc cells during IVD maturation and aging still remain poorly defined. This study investigated novel molecular markers and their age-related changes in the rat IVD. Affymetrix cDNA microarray analysis was conducted to identify a new set of genes characterizing immature nucleus pulposus (NP) cells. Among these markers, select neuronal-related proteins (Basp1, Ncdn and Nrp-1), transcriptional factor (Brachyury T), and cell surface receptors (CD24, CD90, CD155 and CD221) were confirmed by real-time PCR and immunohistochemical (IHC) staining for differential expression between IVD tissue regions and among various ages (1, 12 and 21 months). NP cells generally possessed higher levels of mRNA or protein expression for all aforementioned markers, with the exception of CD90 in anulus fibrosus (AF) cells. In addition, CD protein (CD24 and CD90) and Brachyury (T) expression in immature disc cells were also confirmed via flow cytometry. Similar to IHC staining, results revealed a higher percentage of immature NP cells expressing CD24 and Brachyury, while higher percentage of immature AF cells was stained positively for CD90. Altogether, this study identifies that tissue-specific gene expression and age-related differential expression of the above markers do exist in immature and aged disc cells. These age-related phenotype changes provide a new insight for a molecular profile that may be used to characterize NP cells for developing cell-based regenerative therapy for IVD regeneration.
MeSH Terms
- Aging
- Animals
- Biomarkers
- Gene Expression Profiling
- Gene Expression Regulation
- Intervertebral Disc
- Molecular Sequence Annotation
- Phenotype
- Rats
- Reproducibility of Results