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Cutaneous wound healing is a complex multi-step process that is highly controlled, ensuring efficient repair to damaged tissue and restoring tissue architecture. Multiple cell types play a critical role in wound healing, and perturbations in this can lead to non-healing wounds or scarring and fibrosis. Thus, the process is tightly regulated and controlled. Cellular senescence is defined as irreversible cell cycle arrest and is associated with various phenotypic changes and metabolic alterations and coupled to a secretory program. Its role in wound healing, at least in the acute setting, appears to help promote appropriate mechanisms leading to the complete restoration of tissue architecture. Opposing this is the role of senescence in chronic wounds where it can lead to either chronic non-healing wounds or fibrosis. Given the two opposing outcomes of wound healing in either acute or chronic settings, this has led to disparate views on the role of senescence in wound healing. This review aims to consolidate knowledge on the role of senescence and aging in wound healing, examining the nuances of the roles in the acute or chronic settings, and attempts to evaluate the modulation of this to promote efficient wound healing. [ABSTRACT FROM AUTHOR]

Cellular senescence has been increasingly recognized as a hallmark of cancer, reflecting its association with aging and inflammation, its role as a response to deregulated proliferation and oncogenic stress, and its induction by cancer therapies. While therapy-induced senescence (TIS) has been linked to resistance, recurrence, metastasis, and normal tissue toxicity, TIS also has the potential to enhance therapy response and stimulate anti-tumor immunity. In this review, we examine the Jekyll and Hyde nature of senescent cells (SnCs), focusing on how their persistence while expressing the senescence-associated secretory phenotype (SASP) modulates the tumor microenvironment through autocrine and paracrine mechanisms. Through the SASP, SnCs can mediate both resistance and response to cancer therapies. To fulfill the unmet potential of cancer immunotherapy, we consider how SnCs may influence tumor inflammation and serve as an antigen source to potentiate anti-tumor immune response. This new perspective suggests treatment approaches based on TIS to enhance immune checkpoint blockade. Finally, we describe strategies for mitigating the detrimental effects of senescence, such as modulating the SASP or targeting SnC persistence, which may enhance the overall benefits of cancer treatment. [ABSTRACT FROM AUTHOR]

Cutaneous wound healing is a complex multi-step process that is highly controlled, ensuring efficient repair to damaged tissue and restoring tissue architecture. Multiple cell types play a critical role in wound healing, and perturbations in this can lead to non-healing wounds or scarring and fibrosis. Thus, the process is tightly regulated and controlled. Cellular senescence is defined as irreversible cell cycle arrest and is associated with various phenotypic changes and metabolic alterations and coupled to a secretory program. Its role in wound healing, at least in the acute setting, appears to help promote appropriate mechanisms leading to the complete restoration of tissue architecture. Opposing this is the role of senescence in chronic wounds where it can lead to either chronic non-healing wounds or fibrosis. Given the two opposing outcomes of wound healing in either acute or chronic settings, this has led to disparate views on the role of senescence in wound healing. This review aims to consolidate knowledge on the role of senescence and aging in wound healing, examining the nuances of the roles in the acute or chronic settings, and attempts to evaluate the modulation of this to promote efficient wound healing.

Male ageing is always accompanied by decreased fertility. The forkhead O (FOXO) transcription factor FOXO4 is reported to be highly expressed in senescent cells. Upon activation, it binds p53 in the nucleus, preventing senescent cell apoptosis and maintaining senescent cells in situ. Leydig cells play key roles in assisting spermatogenesis. Leydig cell senescence leads to deterioration of the microenvironment of the testes and impairs spermatogenesis. In this study, we observed that FOXO4-DRI, a specific FOXO4- p53 binding blocker, induced apoptosis in senescent Leydig cells, reduced the secretion of certain Senescence-Associated Secretory Phenotype and improved the proliferation of cocultured GC-1 SPG cells. In naturally aged mice, FOXO4-DRI-treated aged mice exhibited increased sperm quality and improved spermatogenesis.

Type 1 Diabetes (T1D) is a chronic metabolic disease resulting from insulin deficiency due to autoimmune loss of pancreatic β cells. In addition to β cell destruction, it is now accepted that β cell stress and dysfunction, such as senescence, plays a crucial role in the development of the disease. Accumulation of senescent β cells occurs during development of T1D in humans and contributes to the progression of T1D in the nonobese diabetic (NOD) mouse model. Senescent β cells are thought to exacerbate the inflammatory response within the islets by production and secretion of senescence-associated secretory phenotype (SASP). Extracellular vesicles (EVs) from β cells have been shown to carry protein and microRNAs (miRNAs), influencing cellular signaling and may contribute to the development of T1D but it remains to be addressed how senescence impacts β cell EV cargo. In this minireview, we discuss emerging evidence that EV cargo proteins and miRNAs associated with senescence could contribute to the development of T1D and could suggest potential biomarkers and therapeutic targets for the regulation of SASP and elimination of senescent β cells in T1D. Future investigation exploring the intricate relationship between β cell senescence, EVs and miRNAs could pave the way for the development of novel diagnostic techniques and therapeutic interventions.

The development of age-associated diseases is related to the accumulation of senescent cells in the body. These are old non-functional cells with impaired metabolism, which are unable to divide. Such cells are also resistant to programmed cell death and prone to spontaneous production of some inflammatory factors. The accumulation of senescent cells is related to the ageassociated dysfunction of organs and tissues as well as chronic inflammation that enhances with age. In the young organism, senescent cells are removed with the innate immunity system. However, the efficiency of this process decreases with age. Nowadays, more and more evidences are accumulating to support the involvement of specific immunity and T-lymphocytes in the fight against senescent cells. It has great physiological importance since the efficient elimination of senescent cells requires a high diversity of antigen-recognizing receptors to cover the entire spectrumof senescent-associated antigenswith high precision and specificity. Developing the approaches of T-cell immunity stimulation to generate or amplify a physiological immune response against senescent cells can provide new perspectives to extend active longevity. In this mini-review, the authors summarize the current understanding of the role of T-cell immunity in the fight against senescent cells and discuss the prospects of stimulating adaptive immunity for combating the accumulation of senescent cells that occurs with age. [ABSTRACT FROM AUTHOR]

Cellular senescence has been increasingly recognized as a hallmark of cancer, reflecting its association with aging and inflammation, its role as a response to deregulated proliferation and oncogenic stress, and its induction by cancer therapies. While therapy-induced senescence (TIS) has been linked to resistance, recurrence, metastasis, and normal tissue toxicity, TIS also has the potential to enhance therapy response and stimulate anti-tumor immunity. In this review, we examine the Jekyll and Hyde nature of senescent cells (SnCs), focusing on how their persistence while expressing the senescence-associated secretory phenotype (SASP) modulates the tumor microenvironment through autocrine and paracrine mechanisms. Through the SASP, SnCs can mediate both resistance and response to cancer therapies. To fulfill the unmet potential of cancer immunotherapy, we consider how SnCs may influence tumor inflammation and serve as an antigen source to potentiate anti-tumor immune response. This new perspective suggests treatment approaches based on TIS to enhance immune checkpoint blockade. Finally, we describe strategies for mitigating the detrimental effects of senescence, such as modulating the SASP or targeting SnC persistence, which may enhance the overall benefits of cancer treatment.

The development of age-associated diseases is related to the accumulation of senescent cells in the body. These are old non-functional cells with impaired metabolism, which are unable to divide. Such cells are also resistant to programmed cell death and prone to spontaneous production of some inflammatory factors. The accumulation of senescent cells is related to the age-associated dysfunction of organs and tissues as well as chronic inflammation that enhances with age. In the young organism, senescent cells are removed with the innate immunity system. However, the efficiency of this process decreases with age. Nowadays, more and more evidences are accumulating to support the involvement of specific immunity and T-lymphocytes in the fight against senescent cells. It has great physiological importance since the efficient elimination of senescent cells requires a high diversity of antigen-recognizing receptors to cover the entire spectrum of senescent-associated antigens with high precision and specificity. Developing the approaches of T-cell immunity stimulation to generate or amplify a physiological immune response against senescent cells can provide new perspectives to extend active longevity. In this mini-review, the authors summarize the current understanding of the role of T-cell immunity in the fight against senescent cells and discuss the prospects of stimulating adaptive immunity for combating the accumulation of senescent cells that occurs with age.

Osteoarthritis (OA) is the most common age-related degenerative joint disease. Inflammaging, linking inflammation and aging, is found in senescent cells with the secretions of matrix-degrading proteins and proinflammatory cytokines. The senescence-associated secretory phenotype (SASP) plays a very important role in OA progression. However, there remains no effective way to suppress OA progression, especially by suppressing inflammaging and/or the chondrocyte SASP. Recent studies have shown that exosomes derived from hypoxia-cultured BMSCs can regenerate cartilage in OA animal models. Some reports have further indicated that exosomes secreted from MSCs contribute to the efficacy of MSC therapy in OA. However, whether hypoxia-cultured ADSC-secreted exosomes (hypoxia-ADSC-Exos) can alleviate the chondrocyte SASP or OA progression remains unclear. Accordingly, we hypothesized that hypoxia-ADSC-Exos have a beneficial effect on the normal functions of human articular chondrocytes (HACs), can attenuate the SASP of OA-like HACs in vitro, and further suppress OA progression in rats. Hypoxia-ADSC-Exos were derived from ADSCs cultured in 1% O2 and 10% de-Exo-FBS for 48 h. The molecular and cell biological effects of hypoxia-ADSC-Exos were tested on IL1-β-induced HACs as OA-like HACs in vitro, and the efficacy of OA treatment was tested in ACLT-induced OA rats. The results showed that hypoxia-ADSC-Exos had the best effect on GAG formation in normal HACs rather than those cultured in normoxia or hypoxia plus 2% de-Exo-FBS. We further found that hypoxia-ADSC-Exos alleviated the harmful effect in OA-like HACs by decreasing markers of normal cartilage (GAG and type II collagen) and increasing markers of fibrous or degenerative cartilage (type I or X collagen), matrix degradation enzymes (MMP13 and ADAMT5), and inflammatory cytokines (TNFα and IL-6). More importantly, intra-articular treatment with hypoxia-ADSC-Exos suppressed OA progression, as evidenced by the weight-bearing function test and cartilage GAG quantification in ACLT rats. Moreover, through NGS and bioinformatic analysis, seven potential miRNAs were found in hypoxia-ADSC-Exos, which may contribute to regulating cellular oxidative stress and attenuating cell senescence. In summary, we demonstrated that hypoxia-ADSC-Exos, carrying potent miRNAs, not only improve normal HAC function but also alleviate HAC inflammaging and OA progression. The results suggest that hypoxia-ADSC-Exo treatment may offer another strategy for future OA therapy. [ABSTRACT FROM AUTHOR]

Abstract Osteoarthritis (OA) is an age-related cartilage degenerative disease, and chondrocyte senescence has been extensively studied in recent years. Increased numbers of senescent chondrocytes are found in OA cartilage. Selective clearance of senescent chondrocytes in a post-traumatic osteoarthritis (PTOA) mouse model ameliorated OA development, while intraarticular injection of senescent cells induced mouse OA. However, the means and extent to which senescence affects OA remain unclear. Here, we review the latent mechanism of senescence in OA and propose potential therapeutic methods to target OA-related senescence, with an emphasis on immunotherapies. Natural killer (NK) cells participate in the elimination of senescent cells in multiple organs. A relatively comprehensive discussion is presented in that section. Risk factors for OA are ageing, obesity, metabolic disorders and mechanical overload. Determining the relationship between known risk factors and senescence will help elucidate OA pathogenesis and identify optimal treatments.

Male ageing is always accompanied by decreased fertility. The forkhead O (FOXO) transcription factor FOXO4 is reported to be highly expressed in senescent cells. Upon activation, it binds p53 in the nucleus, preventing senescent cell apoptosis and maintaining senescent cells in situ. Leydig cells play key roles in assisting spermatogenesis. Leydig cell senescence leads to deterioration of the microenvironment of the testes and impairs spermatogenesis. In this study, we observed that FOXO4-DRI, a specific FOXO4- p53 binding blocker, induced apoptosis in senescent Leydig cells, reduced the secretion of certain Senescence-Associated Secretory Phenotype and improved the proliferation of cocultured GC-1 SPG cells. In naturally aged mice, FOXO4-DRI-treated aged mice exhibited increased sperm quality and improved spermatogenesis. • Ageing can lead to a decrease in male fertility. We observed that FOXO4-DRI, a specific FOXO4- p53 binding blocker, induced apoptosis in senescent Leydig cells, reduced the secretion of certain Senescence-Associated Secretory Phenotype and improved the proliferation of cocultured GC-1 SPG cells. In naturally aged mice, FOXO4-DRI-treated aged mice exhibited increased sperm quality and improved spermatogenesis. Show its potential of improving ageing male reproductive function. [ABSTRACT FROM AUTHOR]

Cutaneous wound healing is a complex multi-step process that is highly controlled, ensuring efficient repair to damaged tissue and restoring tissue architecture. Multiple cell types play a critical role in wound healing, and perturbations in this can lead to non-healing wounds or scarring and fibrosis. Thus, the process is tightly regulated and controlled. Cellular senescence is defined as irreversible cell cycle arrest and is associated with various phenotypic changes and metabolic alterations and coupled to a secretory program. Its role in wound healing, at least in the acute setting, appears to help promote appropriate mechanisms leading to the complete restoration of tissue architecture. Opposing this is the role of senescence in chronic wounds where it can lead to either chronic non-healing wounds or fibrosis. Given the two opposing outcomes of wound healing in either acute or chronic settings, this has led to disparate views on the role of senescence in wound healing. This review aims to consolidate knowledge on the role of senescence and aging in wound healing, examining the nuances of the roles in the acute or chronic settings, and attempts to evaluate the modulation of this to promote efficient wound healing., Competing Interests: Authors SO’R, EM, and OI were employed by the company Hexislab Limited. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 O’Reilly, Markiewicz and Idowu.)

Cluster of differentiation 38 (CD38) is a cell surface glycoprotein and multifunctional extracellular enzyme. As a NADase, CD38 produces adenosine through the adenosine energy pathway to cause immunosuppression. As a cell surface receptor, CD38 is necessary for immune cell activation and proliferation. The aggregation and polarization of macrophages are affected by the knockout of CD38. Intracellular NAD+ levels are reduced by nuclear receptor liver X receptor-alpha (LXR) agonists in a CD38-dependent manner, thereby reducing the infection of macrophages. Previous studies suggested that CD38 plays an important role in the regulation of macrophage function. Therefore, as a new marker of macrophages, the effect of CD38 on macrophage proliferation, polarization and function; its possible mechanism; the relationship between the expression level of CD38 on macrophage surfaces and disease diagnosis, treatment, etc; and the role of targeting CD38 in macrophage-related diseases are reviewed in this paper to provide a theoretical basis for a comprehensive understanding of the relationship between CD38 and macrophages. [ABSTRACT FROM AUTHOR]

Cluster of differentiation 38 (CD38) is a cell surface glycoprotein and multifunctional extracellular enzyme. As a NADase, CD38 produces adenosine through the adenosine energy pathway to cause immunosuppression. As a cell surface receptor, CD38 is necessary for immune cell activation and proliferation. The aggregation and polarization of macrophages are affected by the knockout of CD38. Intracellular NAD+ levels are reduced by nuclear receptor liver X receptor-alpha (LXR) agonists in a CD38-dependent manner, thereby reducing the infection of macrophages. Previous studies suggested that CD38 plays an important role in the regulation of macrophage function. Therefore, as a new marker of macrophages, the effect of CD38 on macrophage proliferation, polarization and function; its possible mechanism; the relationship between the expression level of CD38 on macrophage surfaces and disease diagnosis, treatment, etc; and the role of targeting CD38 in macrophage-related diseases are reviewed in this paper to provide a theoretical basis for a comprehensive understanding of the relationship between CD38 and macrophages.

Type 1 Diabetes (T1D) is a chronic metabolic disease resulting from insulin deficiency due to autoimmune loss of pancreatic β cells. In addition to β cell destruction, it is now accepted that β cell stress and dysfunction, such as senescence, plays a crucial role in the development of the disease. Accumulation of senescent β cells occurs during development of T1D in humans and contributes to the progression of T1D in the nonobese diabetic (NOD) mouse model. Senescent β cells are thought to exacerbate the inflammatory response within the islets by production and secretion of senescence-associated secretory phenotype (SASP). Extracellular vesicles (EVs) from β cells have been shown to carry protein and microRNAs (miRNAs), influencing cellular signaling and may contribute to the development of T1D but it remains to be addressed how senescence impacts β cell EV cargo. In this minireview, we discuss emerging evidence that EV cargo proteins and miRNAs associated with senescence could contribute to the development of T1D and could suggest potential biomarkers and therapeutic targets for the regulation of SASP and elimination of senescent β cells in T1D. Future investigation exploring the intricate relationship between β cell senescence, EVs and miRNAs could pave the way for the development of novel diagnostic techniques and therapeutic interventions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Motlagh, Pipella and Thompson.)

Neuropsychiatric manifestations targeting the central, peripheral, and autonomic nervous system are common in systemic lupus erythematosus (SLE); collectively, these symptoms are termed neuropsychiatric SLE (NPSLE). Among a wide variety of neuropsychiatric symptoms, depression is observed in about 24-39% of SLE patients. Several cytokines and chemokines have been identified as biomarkers or therapeutic targets of NPSLE; in particular, the levels of type 1 interferons, TNFs, and IL-6 are elevated in SLE patient’s cerebrospinal fluid (CSF), and these factors contribute to the pathology of depression. Here, we show that senescent neural cells accumulate in the hippocampal cornu ammonis 3 (CA3) region in MRL/lpr SLE model mice with depressive behavior. Furthermore, oral administration of fisetin, a senolytic drug, reduced the number of senescent neural cells and reduced depressive behavior in the MRL/lpr mice. In addition, transcription of several senescence and senescence-associated secretory phenotype (SASP) factors in the hippocampal region also decreased after fisetin treatment in the MRL/lpr mice. These results indicate that the accumulation of senescent neural cells in the hippocampus plays a role in NPSLE pathogenesis, and therapies targeting senescent cells may represent a candidate approach to treat NPSLE.

The elderly population is increasing faster than other segments of the population throughout the world. Age is the leading predictor for most chronic diseases and disorders, multimorbidity, geriatric syndromes, and impaired ability to recover from accidents or illnesses. Enhancing the duration of health and independence, termed healthspan, would be more desirable than extending lifespan merely by prolonging the period of morbidity toward the end of life. The geroscience hypothesis posits that healthspan can be extended by targeting fundamental aging mechanisms, rather than attempting to address each age-related disease one at a time, only so the afflicted individual survives disabled and dies shortly afterward of another age-related disease. These fundamental aging mechanisms include, among others, chronic inflammation, fibrosis, stem cell/ progenitor dysfunction, DNA damage, epigenetic changes, metabolic shifts, destructive metabolite generation, mitochondrial dysfunction, misfolded or aggregated protein accumulation, and cellular senescence. These processes appear to be tightly interlinked, as targeting any one appears to affect many of the rest, underlying our Unitary Theory of Fundamental Aging Mechanisms. Interventions targeting many fundamental aging processes are being developed, including dietary manipulations, metformin, mTOR (mechanistic target of rapamycin) inhibitors, and senolytics, which are in early human trials. These interventions could lead to greater healthspan benefits than treating age-related diseases one at a time. To illustrate these points, we focus on cellular senescence and therapies in development to target senescent cells. Combining interventions targeting aging mechanisms with disease-specific drugs could result in more than additive benefits for currently difficult-to-treat or intractable diseases. More research attention needs to be devoted to targeting fundamental aging processes. [ABSTRACT FROM AUTHOR]

Neuropsychiatric manifestations targeting the central, peripheral, and autonomic nervous system are common in systemic lupus erythematosus (SLE); collectively, these symptoms are termed neuropsychiatric SLE (NPSLE). Among a wide variety of neuropsychiatric symptoms, depression is observed in about 24-39% of SLE patients. Several cytokines and chemokines have been identified as biomarkers or therapeutic targets of NPSLE; in particular, the levels of type 1 interferons, TNFs, and IL-6 are elevated in SLE patient's cerebrospinal fluid (CSF), and these factors contribute to the pathology of depression. Here, we show that senescent neural cells accumulate in the hippocampal cornu ammonis 3 (CA3) region in MRL/lpr SLE model mice with depressive behavior. Furthermore, oral administration of fisetin, a senolytic drug, reduced the number of senescent neural cells and reduced depressive behavior in the MRL/lpr mice. In addition, transcription of several senescence and senescence-associated secretory phenotype (SASP) factors in the hippocampal region also decreased after fisetin treatment in the MRL/lpr mice. These results indicate that the accumulation of senescent neural cells in the hippocampus plays a role in NPSLE pathogenesis, and therapies targeting senescent cells may represent a candidate approach to treat NPSLE., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Saito, Miyajima, Yamamoto, Sato, Miura, Fujimiya and Chikenji.)

Senescent cells accumulate in various tissues and organs with aging altering surrounding tissue due to an active secretome, and at least in mice their elimination extends healthy lifespan and ameliorates several chronic diseases. Whether all cell types senesce, including post-mitotic cells, has been poorly described mainly because cellular senescence was defined as a permanent cell cycle arrest. Nevertheless, neurons with features of senescence have been described in old rodent and human brains. In this study we characterized an in vitro model useful to study the molecular basis of senescence of primary rat cortical cells that recapitulates senescent features described in brain aging. We found that in long-term cultures, rat primary cortical neurons displayed features of cellular senescence before glial cells did, and developed a functional senescence-associated secretory phenotype able to induce paracrine premature senescence of mouse embryonic fibroblasts but proliferation of rat glial cells. Functional autophagy seems to prevent neuronal senescence, as we observed an autophagic flux reduction in senescent neurons both in vitro and in vivo , and autophagy impairment induced cortical cell senescence while autophagy stimulation inhibited it. Our findings suggest that aging-associated dysfunctional autophagy contributes to senescence transition also in neuronal cells.

Cellular senescence is a complex cell fate response that is thought to underlie several age-related pathologies. Despite a loss of proliferative potential, senescent cells are metabolically active and produce energy-consuming effectors, including senescence-associated secretory phenotypes (SASPs). Mitochondria play crucial roles in energy production and cellular signaling, but the key features of mitochondrial physiology and particularly of mitochondria-derived peptides (MDPs), remain underexplored in senescence responses. Here, we used primary human fibroblasts made senescent by replicative exhaustion, doxorubicin or hydrogen peroxide treatment, and examined the number of mitochondria and the levels of mitochondrial respiration, mitochondrial DNA methylation and the mitochondria-encoded peptides humanin, MOTS-c, SHLP2 and SHLP6. Senescent cells showed increased numbers of mitochondria and higher levels of mitochondrial respiration, variable changes in mitochondrial DNA methylation, and elevated levels of humanin and MOTS-c. Humanin and MOTS-c administration modestly increased mitochondrial respiration and selected components of the SASP in doxorubicin-induced senescent cells partially via JAK pathway. Targeting metabolism in senescence cells is an important strategy to reduce SASP production for eliminating the deleterious effects of senescence. These results provide insight into the role of MDPs in mitochondrial energetics and the production of SASP components by senescent cells.