CXCR2
C-X-C chemokine receptor type 2 (CXC-R2) (CXCR-2) (CDw128b) (GRO/MGSA receptor) (High affinity interleukin-8 receptor B) (IL-8R B) (IL-8 receptor type 2) (CD182 antigen) [IL8RB]
PublicationsПравить
The oviduct is essential for reproduction. We previously showed that oviduct epithelial cells (OECs) isolated from aged cows expressed higher levels of inflammatory cytokines, including interleukin (IL) 1A and IL1B. In addition, aging is associated with tissue dysfunction and cellular senescence via a senescence-associated secretory phenotype (SASP) and immune cell accumulation. We investigated whether IL1A or IL1B causes SASP production, cellular senescence, and inflammatory responses in bovine OECs. The OECs were isolated from bovine oviducts from young (mean 50.3 months) and aged cows (mean 157.0 months) and cultured. Treatment with IL1A or IL1B induced SASP production (IL8, IL6, TNFA, and CCL2) and mRNA expression of cell adhesion molecules in bovine OECs, but both IL1s did not induce cellular senescence in OECs and migration of polymorphonuclear neutrophils (PMNs). Cultured medium of OECs treated with IL1s, especially IL1B, dramatically induced PMN migration. Treatment with the CCL2 inhibitor, but not IL8 or its receptor CXCR2 inhibitors, significantly reduced immune cell migration in IL1B-treated OEC-cultured medium. Treatment with IL1B increased PMN adhesion to OECs, resulting in further SASP production in OECs due to a PMN-OEC interaction. We suggest that senescence-associated IL1s cause SASP production in bovine OECs and CCL2 induced by IL1B is essential for the migration of immune cells to OECs. Specifically, IL1B regulates PMN migration and adhesion to bovine OECs, and PMNs accelerate inflammatory cytokine production from bovine OECs via a direct interaction. These phenomena may contribute to chronic oviductal inflammation, resulting in subfertility.
Keywords
- CCL2
- cellular senescence
- inflammaging
- senescence-associated secretory phenotype
Pregnancy rate of women decreases with age due to declining quality of oocytes and embryos. However, there is no established method to improve pregnancy rate in aging women. In this study, we identified a senescence-associated secretory phenotype (SASP) factor partially responsible for the decline in embryo implantation potential. Based on microarray analysis using young and aging human embryos at the same morphological grade, 702 genes showed >fivefold increases in aging human blastocysts. Among these genes, C-X-C motif chemokine 5 (CXCL5) showed 7.7-fold increases in aging human blastocysts. However, no-age-dependent changes in expression of the CXCR2, the cognate receptor for CXCL5, were found. In aging mice, Cxcl5 transcript levels were also increased in oocytes and embryos. Treatment of young mouse embryos with CXCL5 decreased implantation rates, together with increased expression of aging markers (P53, P21, Pai-1, and Il-6). Moreover, CXCL5 treatment suppressed trophoblast outgrowth in young mouse blastocysts. Conversely, suppression of CXCL5-CXCR2 signaling in aging mouse embryos using neutralizing antibodies and a receptor antagonist improved the implantation rate, leading to increases in pregnancy and delivery of normal pups. The gene expression pattern of these embryos was comparable to that in young mouse embryos showing enriched cell proliferation-related pathways. In conclusion, we identified CXCL5 as a SASP factor in human and mouse embryos and suppression of CXCL5-CXCR2 signaling during embryo culture improved pregnancy success in aging mice. Future analysis on CXCL5-CXCR2 signaling suppression in human embryos could be the basis to improve embryo development and pregnancy outcome in middle-aged infertile patients.
Keywords
- CXCL5
- CXCR2
- SASP
- aging
- infertility
- preimplantation embryo
Cellular senescence is a fundamental stress response that restrains tumour formation. Yet, senescence cells are also present in non-cancerous states, accumulating exponentially with chronological age and contributing to age- and diabetes-related cellular dysfunction. The identification of hypersecretory and phagocytic behaviours in cells that were once believed to be non-functional has led to a recent explosion of senescence research. Here we discuss the profound, and often opposing, roles identified for short-lived vs. chronic tissue senescence. Transiently induced senescence is required for development, regeneration and acute wound repair, while chronic senescence is widely implicated in tissue pathology. We recently demonstrated that sustained senescence contributes to impaired diabetic healing via the CXCR2 receptor, which when blocked promotes repair. Further studies have highlighted the beneficial effects of targeting a range of senescence-linked processes to fight disease. Collectively, these findings hold promise for developing clinically viable strategies to tackle senescence in chronic wounds and other cutaneous pathologies.
Keywords
- ageing
- diabetes
- senescence
- senolytics
- wound healing
Arguably, the two most important causes of pathological healing in the skin are diabetes and ageing. While these factors have historically been considered independent modifiers of the healing process, recent studies suggest that they may be mechanistically linked. The primary contributor to diabetic pathology is hyperglycaemia, which accelerates the production of advanced glycation end products, a characteristic of ageing tissue. Indeed, advanced age also leads to mild hyperglycaemia. Here, we discuss emerging literature that reveals a hitherto unappreciated link between cellular senescence, diabetes and wound repair. Senescent cells cause widespread destruction of normal tissue architecture in ageing and have been shown to be increased in chronic wounds. However, the role of senescence remains controversial, with several studies reporting beneficial effects for transiently induced senescence in wound healing. We recently highlighted a direct role for senescence in diabetic healing pathology, mediated by the senescence receptor, CXCR2. These findings suggest that targeting local tissue senescence may provide a therapeutic strategy applicable to a broad range of chronic wound types.
Keywords
- advanced glycation end products
- gerontology
- injury
- senolytics
- tissue repair
Aging and cellular senescence are known contributors to the pathophysiology of diabetic nonhealing wounds. However, the dynamic interplay of senescent cells in diabetic wounds is not well understood. Wilkinson et al. show that macrophages, which constitute a large portion of accumulated senescent cells, release a senescence-associated secretory profile (SASP) that is rich in CXCR2 ligands, which drive fibroblasts toward a profibrotic and senescent phenotype. A selective CXCR2 antagonist promoted healing of diabetic wounds, showing a new avenue for potential therapeutic developments.
MeSH Terms
- Aging
- Cellular Senescence
- Diabetes Mellitus
- Fibroblasts
- Humans
- Phenotype
- Wound Healing
Cellular senescence can be broadly defined as a stable, but essentially irreversible, loss of proliferative capacity. Historically, senescence has been described as a negative outcome of advanced cellular age. It is now clear, however, that senescence represents a dynamic autonomous stress response, integral to long-term tumor suppression. Transient induction of a senescent phenotype has actually been suggested to promote regeneration in both liver and skin. Here, we explored the role of senescence in pathological aged and diabetic murine wound healing. Aged and diabetic wounds had greater numbers of senescent cells, and diabetic macrophages maintained altered retention of polarization and produced a CXCR2-enriched senescence-associated secretory phenotype (i.e., SASP). Of translational relevance, targeted expression of CXCR2 in primary human dermal fibroblasts led to paracrine induction of nuclear p21. Furthermore, a selective agonist to CXCR2 was able to reverse delayed healing in diabetic mice and accelerate ex vivo human skin wound healing. Collectively, these data suggest a hitherto unappreciated role for CXCR2 in mediating cellular senescence in pathological wound repair.
MeSH Terms
- Aging
- Analysis of Variance
- Animals
- Biopsy, Needle
- Cells, Cultured
- Cellular Senescence
- Diabetes Mellitus, Experimental
- Disease Models, Animal
- Fibroblasts
- Humans
- Immunohistochemistry
- Mice
- Mice, Inbred C57BL
- Receptors, Interleukin-8B
- Reference Values
- Skin Ulcer
- Wound Healing
- Wounds and Injuries
Neutrophils eliminate pathogens efficiently but can inflict severe damage to the host if they over-activate within blood vessels. It is unclear how immunity solves the dilemma of mounting an efficient anti-microbial defense while preserving vascular health. Here, we identify a neutrophil-intrinsic program that enabled both. The gene Bmal1 regulated expression of the chemokine CXCL2 to induce chemokine receptor CXCR2-dependent diurnal changes in the transcriptional and migratory properties of circulating neutrophils. These diurnal alterations, referred to as neutrophil aging, were antagonized by CXCR4 (C-X-C chemokine receptor type 4) and regulated the outer topology of neutrophils to favor homeostatic egress from blood vessels at night, resulting in boosted anti-microbial activity in tissues. Mice engineered for constitutive neutrophil aging became resistant to infection, but the persistence of intravascular aged neutrophils predisposed them to thrombo-inflammation and death. Thus, diurnal compartmentalization of neutrophils, driven by an internal timer, coordinates immune defense and vascular protection.
MeSH Terms
- Animals
- Blood Vessels
- Candida albicans
- Cells, Cultured
- Cellular Senescence
- Chemokine CXCL2
- Circadian Rhythm
- Host-Pathogen Interactions
- Humans
- Inflammation
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Neutrophil Infiltration
- Neutrophils
- Phagocytosis
- Receptors, CXCR4
- Time Factors
Keywords
- Bmal1
- CXCR2
- CXCR4
- Candida albicans
- Neutrophil
- circadian clock
- infection
- inflammation
- myocardial infarction
- neutrophil aging
Senescent cells are characterized by an increased secretion of inflammatory and growth factors, known as the "senescence-associated secretory phenotype" (SASP), producing a pro-tumoral and pro-angiogenic microenvironment. This work proposes chronic resveratrol treatment (5 µM for 5 weeks, termed R5) of senescent MRC5 fibroblasts as a mean to mimic and target the angiogenic trait of stromal fibroblast SASP. Senescent fibroblast conditioned medium (CM sen) was effective in enhancing the angiogenic properties of endothelial colony-forming cells (ECFCs), that is, invasive activity and capillary morphogenesis capability in vitro, that were significantly reduced when conditioned media were collected after resveratrol pretreatment (CM senR5). The attenuation of ECFC angiogenic phenotype induced by CM senR5 was accompanied by reduced protein levels of epidermal growth factor and urokinase plasminogen activator receptors (EGFR, uPAR), and by a related decreased activation of receptor-tyrosine-kinase signaling pathways. IL8 levels were found reduced in CM senR5 compared to CM sen, with the associated reduction of IL8-CXCR2 binding in ECFCs. IL8-subtraction mitigated the pro-angiogenic features of CM sen and the associated intracellular signaling in ECFCs, indicating a prominent role of IL8 in the pro-angiogenic effects of CM sen. IL8 modulation is an important mechanism underlying the antiangiogenic activity of resveratrol on MRC5 SASP.
MeSH Terms
- Antigens, Surface
- Cells, Cultured
- Cellular Senescence
- Culture Media, Conditioned
- Endothelial Cells
- Epidermal Growth Factor
- ErbB Receptors
- Fibroblasts
- Humans
- Interleukin-8
- Neovascularization, Physiologic
- Phenotype
- Receptors, Urokinase Plasminogen Activator
- Resveratrol
- Signal Transduction
Keywords
- Cellular senescence
- Endothelial cell
- IL8
- Microenvironment
- Resveratrol
Mesenchymal stem cells (MSCs) have shown promise for use in cell therapy, and due to their tumor tropism can serve as vehicles for delivering therapeutic agents to tumor sites. Because interleukin-8 (IL-8) is known to mediate the protumor effect of MSCs, elimination of IL-8 secretion by MSCs may enhance their safety for use in cancer gene therapy. However, little is known concerning the effect of endogenously secreted IL-8 on MSCs. We performed studies using placenta-derived MSCs (PMSCs) to determine whether knockdown of IL-8 would influence their biological activity. We first verified that IL-8 and its membrane receptor CXCR2, but not CXCR1, were highly expressed in PMSCs. We then employed lentivirus-mediated small hairpin RNA interference to generate stable IL-8-silenced PMSCs, which displayed a variety of characteristic senescent phenotypes. We observed that at day 9 post-transfection, IL-8-silenced PMSCs had become larger and displayed a more flattened appearance when compared with their controls. Moreover, their proliferation, colony forming unit-fibroblast formation, adipogenic and osteogenic differentiation, and immunosuppressive potentials were significantly impaired. Enhanced senescence-associated β-galactosidase (SA-β-gal) activity and specific global gene expression profiles confirmed that IL-8 silencing evoked the senescence process in PMSCs. Increased levels of p-Akt and decreased levels of FOXO3a protein expression suggested that reactive oxygen species played a role in the initiation and maintenance of senescence in IL-8-silenced PMSCs. Notably, the majority of CXCR2 ligands were downregulated in presenescent IL-8-silenced PMSCs but upregulated in senescent cells, indicating an antagonistic pleiotropy of the IL-8/CXCR2 signaling pathway in PMSCs. This effect may promote the proliferation of young cells and accelerate senescence of old cells.
MeSH Terms
- Cell Proliferation
- Cellular Senescence
- Female
- Gene Knockdown Techniques
- Humans
- Interleukin-8
- Mesenchymal Stem Cells
- Placenta
- Pregnancy
- Receptors, Interleukin-8B
Keywords
- IL-8
- knockdown
- lentiviral shRNA
- mesenchymal stem cells
- placenta
- senescence
Dysfunctional neutrophils with advanced age are a hallmark of immunosenescence. Reduced migration and bactericidal activity increase the risk of infection. It remains unclear why neutrophil dysfunction occurs with age. Physical activity and structured exercise have been suggested to improve immune function in the elderly. The aim of this study was to assess a comprehensive range of neutrophil functions and determine their association with habitual physical activity. Physical activity levels were determined in 211 elderly (67±5years) individuals by 7-days of accelerometry wear. Twenty of the most physically active men and women were matched for age and gender to twenty of the least physically active individuals. Groups were compared for neutrophil migration, phagocytosis, oxidative burst, cell surface receptor expression, metabolic health parameters and systemic inflammation. Groups were also compared against ten young participants (23±4years). The most active group completed over twice as many steps/day as the least active group (p<0.001), had lower BMI's (p=0.007) and body fat percentages (p=0.029). Neutrophils migrated towards IL-8 better in the most active group compared to the least active (p<0.05) and was comparable to that of the young (p>0.05). These differences remained after adjusting for BMI, body fat and plasma metabolic markers which were different between groups. Correlations revealed that steps/day, higher adiponectin and lower insulin were positively associated with migratory ability (p<0.05). There was no difference in expression of the chemokine receptors CXCR1 or CXCR2 (p>0.05 for both). CD11b was higher in the most active group compared to the least active (p=0.048). No differences between activity groups or young controls were observed for neutrophil phagocytosis or oxidative burst in response to Escherichia coli (p>0.05). The young group had lower concentrations of IL-6, IL-8, MCP-1, CRP, IL-10 and IL-13 (p<0.05 for all) with no differences between the two older groups. These data suggest that impaired neutrophil migration, but not bactericidal function, in older adults may be, in part, the result of reduced physical activity. A 2-fold difference in physical activity is associated with better preserved neutrophil migratory dynamics in healthy older people. As a consequence increasing habitual physical activity may be beneficial for neutrophil mediated immunity.
MeSH Terms
- Aged
- Aging
- Cell Movement
- Exercise
- Female
- Humans
- Immunity, Innate
- Immunosenescence
- Male
- Neutrophils
Keywords
- Ageing
- Immunosenescence
- Inflammation
- Innate immunity
- Migration
- Neutrophil
- Physical activity
Truncation of tau protein is considered an early event in Alzheimer's disease (AD) and is believed to play a major pathogenic role in sporadic AD. However, causative factors that trigger tau truncation in AD remain poorly understood. In the present study, we demonstrate that CXCL1 (C-X-C motif ligand 1), a specific ligand for the chemokine receptor CXCR2, induced cleavage of tau at ASP421 in a caspase-3-dependent manner in long-term but not short-term cultured neurons. The cleaved tau formed varicosities or bead-like structures along the neurites, an abnormal distribution of tau induced by CXCL1 that has not been observed previously. CXCL1-induced activation of GSK3β and the subsequent phosphorylation of tau preceded and were required for caspase-3 activation and tau cleavage. Moreover, intrahippocampal microinjection of lentiviral CXCL1 induced tau cleavage in hippocampal neurons in aged (15-18 months of age) but not adult mice (5-10 months of age). Our data highlight a new role of CXCR2 in tau cleavage and suggest that targeting CXCR2 may offer therapeutic benefits to patients with AD and potentially other tauopathies.
MeSH Terms
- Aging
- Animals
- Caspase 3
- Cells, Cultured
- Chemokine CXCL1
- Embryo, Mammalian
- Female
- Hippocampus
- Mice
- Mice, Inbred C57BL
- Microinjections
- Microtubule-Associated Proteins
- Mutation
- Neurons
- Pregnancy
- Rats
- Rats, Sprague-Dawley
- Time Factors
- Transfection
- tau Proteins
Keywords
- CXCL1
- CXCR2
- Caspase-3
- hippocampal neurons
- tau cleavage
Mammalian cells may undergo permanent growth arrest/senescence when they incur excessive DNA damage. As a key player during DNA damage response (DDR), p53 transactivates an array of target genes that are involved in various cellular processes including the induction of cellular senescence. Chemokine receptor CXCR2 was previously reported to mediate replicative and oncogene-induced senescence in a DDR and p53-dependent manner. Here, we report that CXCR2 is upregulated in various types of cells in response to genotoxic or oxidative stress. Unexpectedly, we found that the upregulation of CXCR2 depends on the function of p53. Like other p53 target genes such as p21, CXCR2 is transactivated by p53. We identified a p53-binding site in the CXCR2 promoter that responds to changes in p53 functional status. Thus, CXCR2 may act downstream of p53. While the senescence-associated secretory phenotype (SASP) exhibits a kinetics that is distinct from that of CXCR2 expression and does not require p53, it reinforces senescence. We further showed that the cellular senescence caused by CXCR2 upregulation is mediated by p38 activation. Our results thus demonstrate CXCR2 as a critical mediator of cellular senescence downstream of p53 in response to DNA damage.
MeSH Terms
- Animals
- Base Sequence
- Cell Line, Tumor
- Cellular Senescence
- DNA Damage
- Enzyme Activation
- MAP Kinase Signaling System
- Mice
- Molecular Sequence Data
- Phenotype
- Radiation, Ionizing
- Receptors, Interleukin-8B
- Transcription, Genetic
- Transcriptional Activation
- Tumor Suppressor Protein p53
- Up-Regulation
- p38 Mitogen-Activated Protein Kinases
Keywords
- CXCR2
- p38
- p53
- senescence
- transcriptional activation
Globoid-cell Leukodystrophy (GLD; Krabbe's disease) is a rapidly progressing inherited demyelinating disease caused by a deficiency of the lysosomal enzyme Galactosylceramidase (GALC). Deficiency of GALC leads to altered catabolism of galactosylceramide and the cytotoxic lipid, galactosylsphingosine (psychosine). This leads to a rapidly progressive fatal disease with spasticity, cognitive disability and seizures. The murine model of GLD (Twitcher; GALC-/-) lacks the same enzyme and has similar clinical features. The deficiency of GALC leads to oligodendrocyte death, profound neuroinflammation, and the influx of activated macrophages into the CNS. We showed previously that keratinocyte chemoattractant factor (KC) is highly elevated in the CNS of untreated Twitcher mice and significantly decreases after receiving a relatively effective therapy (bone marrow transplantation combined with gene therapy). The action of KC is mediated through the CXCR2 receptor and is a potent chemoattractant for macrophages and microglia. KC is also involved in oligodendrocyte migration and proliferation. Based on the commonalities between the disease presentation and the functions of KC, we hypothesized that KC and/or CXCR2 contribute to the pathogenesis of GLD. Interestingly, the course of the disease is not significantly altered in KC- or CXCR2-deficient Twitcher mice. There is also no alteration in inflammation or demyelination patterns in these mice. Furthermore, transplantation of CXCR2-deficient bone marrow does not alter the progression of the disease as it does in other models of demyelination. This study highlights the role of multiple redundant cytokines and growth factors in the pathogenesis of GLD.
MeSH Terms
- Animals
- Bone Marrow
- Cell Proliferation
- Central Nervous System
- Chemokine CXCL1
- Disease Models, Animal
- Disease Progression
- Flow Cytometry
- Galactosylceramidase
- Inflammation
- Leukodystrophy, Globoid Cell
- Longevity
- Lumbar Vertebrae
- Mice, Inbred C57BL
- Oligodendroglia
- Receptors, Interleukin-8B