High glucose-induced replicative senescence: point of no return and effect of telomerase

Cell senescence in cardiometabolic diseases

Cellular senescence has been implicated in many age-related pathologies including atherosclerosis, heart failure, age-related cardiac remodeling, diabetic cardiomyopathy and the metabolic syndrome. Here, we will review the characteristics of senescent cells and their endogenous regulators, and summarize the metabolic stressors that induce cell senescence. We will discuss the evidence of cell senescence in the onset and progression of several cardiometabolic diseases and the therapeutic potential of anti-senescence therapies.

A nutrigeroscience approach: Dietary macronutrients and cellular senescence

Cellular senescence, a process in which a cell exits the cell cycle in response to stressors, is one of the hallmarks of aging. Senescence and the senescence-associated secretory phenotype (SASP)-a heterogeneous set of secreted factors that disrupt tissue homeostasis and promote the accumulation of senescent cells-reprogram metabolism and can lead to metabolic dysfunction. Dietary interventions have long been studied as methods to combat age-associated metabolic dysfunction, promote health, and increase lifespan. A growing body of literature suggests that senescence is responsive to diet, both to calories and specific dietary macronutrients, and that the metabolic benefits of dietary interventions may arise in part through reducing senescence. Here, we review what is currently known about dietary macronutrients' effect on senescence and the SASP, the nutrient-responsive molecular mechanisms that may mediate these effects, and the potential for these findings to inform the development of a nutrigeroscience approach to healthy aging.

Therapy-Induced Cellular Senescence: Potentiating Tumor Elimination or Driving Cancer Resistance and Recurrence?

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.

Protective Effect of Curcumin on the Tight Junction Integrity and Cellular Senescence in Human Retinal Pigment Epithelium of Early Diabetic Retinopathy

Diabetic retinopathy (DR) is a secondary complication of diabetes that can lead to visual impairment and blindness. The retinal pigment epithelium (RPE) is a monolayer of pigment cells that forms the blood-retinal barrier (BRB) via tight junction (TJ) proteins and plays a crucial role in the physiological function of the retina. Hyperglycemia induces RPE death and BRB breakdown, which accelerates the process of DR. Curcumin, an active extract of Curcuma longa , has anti-inflammatory, antioxidant, antiapoptotic, and neuroprotective properties. However, the effect of Curcumin on the BRB under high glucose conditions remains unknown. This study aimed to investigate the protective effects of Curcumin on RPE physiology in vitro and in vivo . Curcumin significantly alleviated cell viability inhibition under high glucose conditions. Moreover, high glucose reduced extracellular signal-regulated kinase and Akt pathways activation to diminish RPE cell growth but reversed by Curcumin treatment. Curcumin protected not only TJ integrity but also retinoid regeneration through TJ proteins and isomerase modulation in diabetic retina. Furthermore, Curcumin decreased the expression of angiogenic factor to inhibit retinal neovascularization. Finally, Curcumin treatment markedly reduced apoptosis during hyperglycemia. In conclusion, Curcumin can alleviate the progression of DR by promoting RPE survival, TJ integrity, retinoid isomerase activity, RPE senescence inhibition, and neovascularization. Therefore, Curcumin exhibits high potential for use as a therapeutic agent for early DR.

Revolutionizing Diabetic Foot Ulcer Care: The Senotherapeutic Approach

Diabetic foot ulcers (DFUs) are a prevalent and profoundly debilitating complication that afflicts individuals with diabetes mellitus (DM). These ulcers are associated with substantial morbidity, recurrence rates, disability, and mortality, imposing substantial economic, psychological, and medical burdens. Timely detection and intervention can mitigate the morbidity and disparities linked to DFU. Nevertheless, current therapeutic approaches for DFU continue to grapple with multifaceted limitations. A growing body of evidence emphasizes the crucial role of cellular senescence in the pathogenesis of chronic wounds. Interventions that try to delay cellular senescence, eliminate senescent cells (SnCs), or suppress the senescence-associated secretory phenotype (SASP) have shown promise for helping chronic wounds to heal. In this context, targeting cellular senescence emerges as a novel therapeutic strategy for DFU. In this comprehensive review, we look at the pathology and treatment of DFU in a systematic way. We also explain the growing importance of investigating SnCs in DFU and highlight the great potential of senotherapeutics that target SnCs in DFU treatment. The development of efficacious and safe senotherapeutics represents a pioneering therapeutic approach aimed at enhancing the quality of life for individuals affected by DFU.

Distinct roles of telomerase activity in age-related chronic diseases: An update literature review

Although telomerase has low activity in somatic quiescent cells, it plays an significant roles in regenerative cells such as endothelial cells, hepatocytes, epithelial cells, and hemocytes. Telomerase activity and telomere length are critical factors in age-related chronic diseases as they are closely related to cell senescence. However, whether telomerase activity plays a key role in disease progression or whether the role of telomerase is unified among different diseases are unresolved. Considering that aging is the most important risk factor for neurodegenerative and metabolic diseases, this article will analyze the evidence, mechanism, and therapeutic potential of telomerase activity in several chronic disease, including type 2 diabetes, neurodegenerative diseases, atherosclerosis, heart failure and non-alcoholic fatty liver disease, in order to provide clues for the use of telomerase activity to target the treatment of age-related chronic diseases.

Skin Cancer Microenvironment: What We Can Learn from Skin Aging?

Aging is a natural intrinsic process associated with the loss of fibrous tissue, a slower cell turnover, and a reduction in immune system competence. In the skin, the continuous exposition of environmental factors superimposes extrinsic damage, mainly due to ultraviolet radiation causing photoaging. Although not usually considered a pathogenic event, photoaging affects cutaneous biology, increasing the risk of skin carcinogenesis. At the cellular level, aging is typified by the rise of senescence cells a condition characterized by reduced or absent capacity to proliferate and aberrant hyper-secretory activity. Senescence has a double-edged sword in cancer biology given that senescence prevents the uncontrolled proliferation of damaged cells and favors their clearance by paracrine secretion. Nevertheless, the cumulative insults and the poor clearance of injured cells in the elderly increase cancer incidence. However, there are not conclusive data proving that aged skin represents a permissive milieu for tumor onset. On the other hand, tumor cells are capable of activating resident fibroblasts onto a pro-tumorigenic phenotype resembling those of senescent fibroblasts suggesting that aged fibroblasts might facilitate cancer progression. This review discusses changes that occur during aging that can prime neoplasm or increase the aggressiveness of melanoma and non-melanoma skin cancer.

On the Potential Role of the Antioxidant Couple Vitamin E/Selenium Taken by the Oral Route in Skin and Hair Health

The relationship between oxidative stress and skin aging/disorders is well established. Many topical and oral antioxidants (vitamins C and E, carotenoids, polyphenols) have been proposed to protect the skin against the deleterious effect induced by increased reactive oxygen species production, particularly in the context of sun exposure. In this review, we focused on the combination of vitamin E and selenium taken in supplements since both molecules act in synergy either by non-enzymatic and enzymatic pathways to eliminate skin lipids peroxides, which are strongly implicated in skin and hair disorders.

ER stress in cardiac aging, a current view on the D-galactose model

Longitudinal studies are mandatory to study aging, however, they have certain drawbacks, for example, they require strict maintenance that is expensive given the breeding time (approximately 2 years) and with a low survival rate, having some animals to study very limitedly. In vitro studies provide useful and invaluable information on the cellular and molecular mechanisms that help understand the aging process to overcome these aspects. In particular, the model of premature aging induced by chronic exposure to D-galactose (D-Gal) offers a very similar picture to that which occurs in natural aging. This model mimics most of the old animals' cellular processes, such as oxidative stress, mitochondrial dysfunction, increased advanced glycation end products (AGEs), inflammation, and senescence-associated secretory phenotype (SASP). However, the information related to the endoplasmic reticulum (ER) stress and, subsequently, the unfolded protein response (UPR) is not fully elucidated. Therefore, this review brings together the most current information on this response in the D-Gal-induced aging model and its effect on cardiac structure and function.

Pro-tumorigenic role of type 2 diabetes-induced cellular senescence in colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related mortality worldwide. The disease still remains incurable and highly lethal in the advanced stage, representing a global health concern. Therefore, it is essential to understand the causes and risk factors leading to its development. Because age-related cellular senescence and type 2 diabetes (T2D) have been recognised as risk factors for CRC development, the recent finding that type 2 diabetic patients present an elevated circulating volume of senescent cells raises the question whether type 2 diabetes facilitates the process of CRC tumorigenesis by inducing premature cell senescence. In this review, we will discuss the mechanisms according to which T2D induces cellular senescence and the role of type 2 diabetes-induced cellular senescence in the pathogenesis and progression of colorectal cancer. Lastly, we will explore the current therapeutic approaches and challenges in targeting senescence.

Predictive factors and clinical effects of diabetic hand: A prospective study with 1-year follow-up

AIMS

Diabetes mellitus is considered an etiological factor for hand-related conditions that are grouped under the term "diabetic hand" (DH), which includes limited joint mobility, Dupuytren's contracture, carpal tunnel syndrome, and trigger finger. This study aimed to identify predictive factors and the clinical effects of DH development among patients with diabetes.

PATIENTS AND METHODS

Consecutive Japanese adults with diabetes were prospectively recruited at a single outpatient center. We assessed the presence of DH at baseline and at the 1-year follow-up, which was considered present if the patient exhibited one or more of the hand disorders at either examination.

RESULTS

The 590 eligible subjects had a mean age of 57 years and included 155 patients (26%) with DH. Binary logistic regression analysis revealed that DH was significantly associated with older age, longer diabetes duration, and higher body mass index. Patients with DH had significantly lower hand function and quality of life (QOL) scores. We assessed 476 patients at the 1-year follow-up, including 96 patients (20%) who had DH at baseline. Although 25 of the 96 patients (26%) experienced resolution of DH without specific treatment, 83 of 380 patients (22%) without DH at baseline had developed new DH-related conditions. At the 1-year follow-up, the group with DH was significantly older than that without DH.

CONCLUSION

Older age and prolonged duration of diabetes predicted the development of DH. Patients who are not old and do not have a prolonged duration of diabetes may experience DH resolution without specific treatment.

Crosstalk Between Senescent Bone Cells and the Bone Tissue Microenvironment Influences Bone Fragility During Chronological Age and in Diabetes

Bone is a complex organ serving roles in skeletal support and movement, and is a source of blood cells including adaptive and innate immune cells. Structural and functional integrity is maintained through a balance between bone synthesis and bone degradation, dependent in part on mechanical loading but also on signaling and influences of the tissue microenvironment. Bone structure and the extracellular bone milieu change with age, predisposing to osteoporosis and increased fracture risk, and this is exacerbated in patients with diabetes. Such changes can include loss of bone mineral density, deterioration in micro-architecture, as well as decreased bone flexibility, through alteration of proteinaceous bone support structures, and accumulation of senescent cells. Senescence is a state of proliferation arrest accompanied by marked morphological and metabolic changes. It is driven by cellular stress and serves an important acute tumor suppressive mechanism when followed by immune-mediated senescent cell clearance. However, aging and pathological conditions including diabetes are associated with accumulation of senescent cells that generate a pro-inflammatory and tissue-destructive secretome (the SASP). The SASP impinges on the tissue microenvironment with detrimental local and systemic consequences; senescent cells are thought to contribute to the multimorbidity associated with advanced chronological age. Here, we assess factors that promote bone fragility, in the context both of chronological aging and accelerated aging in progeroid syndromes and in diabetes, including senescence-dependent alterations in the bone tissue microenvironment, and glycation changes to the tissue microenvironment that stimulate RAGE signaling, a process that is accelerated in diabetic patients. Finally, we discuss therapeutic interventions targeting RAGE signaling and cell senescence that show promise in improving bone health in older people and those living with diabetes.

Aging Challenges. Perceived Age – a New Predictor of Longevity?

The ageing process is accompanied by the manifestation of many characteristics, so-called biomarkers, which can be quantified and used to assess a patient's health status. One of these signs is the progressive decline of a human's facial look, which is described by the concept of 'perceived age'. Facial aging is the most important parameter of perceived age. However, over the years, researchers have identified risk factors that affect the facial skin, including smoking, systematic consumption of alcoholic beverages, overweight or underweight, environmental conditions, and psychosocial determinants. The influence of psychological state on the appearance and life prognosis is shown. The authors presented data from the international literature on the study of perceived age. The frontiers of using perceived age as a biomarker of aging were Danish scientists who developed the main methodological approaches to determine this indicator. One such methodology used in population studies has been the clinical technique of assessing perceived age through photography. The review presents this methodology in detail, with its advantages and modifications. The authors conclude that the measurement of an individual's perceived age can serve not only as a prognostic indicator,  but also over time can become a   useful marker of the effectiveness of various treatments. Until now perceived age has hardly been studied in population studies, the authors presented data from the works of V.A.  Labunskaya, G.V.  Serikov,  T.A.  Shkurko who develop the direction related to psychology of perceived age  and in their studies use social-psychological approaches of appearance assessment.

Shortened Leukocyte Telomere Length Is Associated With Glycemic Progression in Type 2 Diabetes: A Prospective and Mendelian Randomization Analysis

OBJECTIVE

Several studies support associations between relative leukocyte telomere length (rLTL), a biomarker of biological aging and type 2 diabetes. This study investigates the relationship between rLTL and the risk of glycemic progression in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this cohort study, consecutive Chinese patients with type 2 diabetes (N = 5,506) from the Hong Kong Diabetes Register with stored baseline DNA and available follow-up data were studied. rLTL was measured using quantitative PCR. Glycemic progression was defined as the new need for exogenous insulin.

RESULTS

The mean (SD) age of the 5,349 subjects was 57.0 (13.3) years, and mean (SD) follow-up was 8.8 (5.4) years. Baseline rLTL was significantly shorter in the 1,803 subjects who progressed to insulin requirement compared with the remaining subjects (4.43 ± 1.16 vs. 4.69 ± 1.20). Shorter rLTL was associated with a higher risk of glycemic progression (hazard ratio [95% CI] for each unit decrease [to ∼0.2 kilobases]: 1.10 [1.06-1.14]), which remained significant after adjusting for confounders. Baseline rLTL was independently associated with glycemic exposure during follow-up (β = -0.05 [-0.06 to -0.04]). Each 1-kilobase decrease in absolute LTL was on average associated with a 1.69-fold higher risk of diabetes progression (95% CI 1.35-2.11). Two-sample Mendelian randomization analysis showed per 1-unit genetically decreased rLTL was associated with a 1.38-fold higher risk of diabetes progression (95% CI 1.12-1.70).

CONCLUSIONS

Shorter rLTL was significantly associated with an increased risk of glycemic progression in individuals with type 2 diabetes, independent of established risk factors. Telomere length may be a useful biomarker for glycemic progression in people with type 2 diabetes.

C-peptide is a predictor of telomere shortening: A five-year longitudinal study

AIM

Relative telomere length (RTL) predicts the development of many age-related diseases. Yet, few studies have evaluated their longitudinal effect on RTL. We investigated longitudinally the association between cardiometabolic risk factors and RTL.

METHODS

This was a longitudinal study with a 5-year follow-up period, based on data collected in 2014 and 2019. Of 478 participants in 2014, 198 consented to be followed-up in 2019. The associations between RTL and risk factors were analyzed using t-test, ANOVA or simple linear regression as applicable.

RESULTS

RTL was significantly shortened after 5 years (P<0.001). Older age (P=0.018) and gender (P=0.05) were significantly associated with shorter RTL at follow-up. Higher baseline C-peptide correlated with shorter RTL (P=0.04) and shortening of RTL (P=0.03) after 5 years. Multivariate linear regression including both age and gender revealed a significant trend for C-peptide and change in RTL after 5 years (P=0.04). Interestingly, there was a trend of shorter RTL at follow-up with diabetes, though the findings were not statistically significant.

CONCLUSIONS

Higher C-peptide level contributes to telomere shortening over time, suggesting that metabolic dysregulation may play a role in early aging. Further understanding of this relationship and addressing high C-peptide levels can be important to prevent premature aging.

COVITALE 2020 from eastern Indian population: imageologists perspective, a learning curve

Background

High-resolution computed tomography (HRCT) chest becomes a valuable diagnostic tool for identifying patients infected with Coronavirus Disease 2019 (COVID-19) in the early stage, where patients may be asymptomatic or with non-specific pulmonary symptoms. An early diagnosis of COVID-19 is of utmost importance, so that patients can be isolated and treated in time, eventually preventing spread of the disease, improving the prognosis and reducing the mortality. In this paper, we have highlighted our radiological experience of dealing with the pandemic crisis of 2020 through the study of HRCT thorax, lung ultrasonography, chest X-rays and artificial intelligence (AI).

Results

Results of CT thorax analysis have been given in detail. We had also compared CT severity score (CTSS) with clinical and laboratory parameters. Correlation of CTSS with SpO2 values and comorbidities was also studied. We also analysed manual CTSS with the CTSS scored calculated by the AI software.

Conclusions

CTSS and use of COVID-19 Reporting and Data System (CORADS) result in accuracy and uniform percolation of information among the clinicians. Bed-side X-rays and ultrasonography have played a role where the patients could not be shifted for CT scan. The possibility of predicting impending or progression of hypoxia was not possible when SpO2 mapping was correlated with the CTSS. AI was alternatively tried with available software (CT pneumonia analysis) which was not so appropriate considering the imaging patterns in the bulk of atypical category.

Senescence and Type 2 Diabetic Cardiomyopathy: How Young Can You Die of Old Age?

Inflammation is well understood to be a physiological process of ageing however it also underlies many chronic diseases, including conditions without an obvious pathogenic inflammatory element. Recent findings have unequivocally identified type 2 diabetes (T2D) as a chronic inflammatory disease characterized by inflammation and immune senescence. Immunosenescence is a hallmark of the prolonged low-grade systemic inflammation, in particular associated with metabolic syndrome and can be a cause as well as a consequence of T2D. Diabetes is a risk factor for cardiovascular mortality and remodelling and with particular changes to myocardial structure, function, metabolism and energetics collectively resulting in diabetic cardiomyopathy. Both cardiomyocytes and immune cells undergo metabolic remodelling in T2D and as a result become trapped in a vicious cycle of lost metabolic flexibility, thus losing their key adaptive mechanisms to dynamic changes in O₂ and nutrient availability. Immunosenescence driven by metabolic stress may be both the cause and key contributing factor to cardiac dysfunction in diabetic cardiomyopathy by inducing metabolic perturbations that can lead to impaired energetics, a strong predictor of cardiac mortality. Here we review our current understanding of the cross-talk between inflammaging and cardiomyocytes in T2D cardiomyopathy. We discuss potential mechanisms of metabolic convergence between cell types which, we hypothesize, might tip the balance between resolution of the inflammation versus adverse cardiac metabolic remodelling in T2D cardiomyopathy. A better understanding of the multiple biological paradigms leading to T2D cardiomyopathy including the immunosenescence associated with inflammaging will provide a powerful target for successful therapeutic interventions.

Obesity, Senescence, and Senolytics

Obesity is a major risk factor for the development of comorbidities such as type 2 diabetes, neurodegenerative disorders, osteoarthritis, cancer, cardiovascular and renal diseases. The onset of obesity is linked to an increase of senescent cells within adipose tissue and other organs. Cellular senescence is a stress response that has been shown to be causally linked to aging and development of various age-related diseases such as obesity. The senescence-associated-secretory phenotype of senescent cells creates a chronic inflammatory milieu that leads to local and systemic dysfunction. The elimination of senescent cells using pharmacological approaches (i.e., senolytics) has been shown to delay, prevent, or alleviate obesity-related organ dysfunction.

The metabolic roots of senescence: mechanisms and opportunities for intervention

Cellular senescence entails a permanent proliferative arrest, coupled to multiple phenotypic changes. Among these changes is the release of numerous biologically active molecules collectively known as the senescence-associated secretory phenotype, or SASP. A growing body of literature indicates that both senescence and the SASP are sensitive to cellular and organismal metabolic states, which in turn can drive phenotypes associated with metabolic dysfunction. Here, we review the current literature linking senescence and metabolism, with an eye toward findings at the cellular level, including both metabolic inducers of senescence and alterations in cellular metabolism associated with senescence. Additionally, we consider how interventions that target either metabolism or senescent cells might influence each other and mitigate some of the pro-aging effects of cellular senescence. We conclude that the most effective interventions will likely break a degenerative feedback cycle by which cellular senescence promotes metabolic diseases, which in turn promote senescence.

Keeping zombies alive: The ER-mitochondria Ca2+ transfer in cellular senescence

Cellular senescence generates a permanent cell cycle arrest, characterized by apoptosis resistance and a pro-inflammatory senescence-associated secretory phenotype (SASP). Physiologically, senescent cells promote tissue remodeling during development and after injury. However, when accumulated over a certain threshold as happens during aging or after cellular stress, senescent cells contribute to the functional decline of tissues, participating in the generation of several diseases. Cellular senescence is accompanied by increased mitochondrial metabolism. How mitochondrial function is regulated and what role it plays in senescent cell homeostasis is poorly understood. Mitochondria are functionally and physically coupled to the endoplasmic reticulum (ER), the major calcium (Ca²⁺) storage organelle in mammalian cells, through special domains known as mitochondria-ER contacts (MERCs). In this domain, the release of Ca²⁺ from the ER is mainly regulated by inositol 1,4,5-trisphosphate receptors (IP3Rs), a family of three Ca²⁺ release channels activated by a ligand (IP3). IP3R-mediated Ca²⁺ release is transferred to mitochondria through the mitochondrial Ca²⁺ uniporter (MCU), where it modulates the activity of several enzymes and transporters impacting its bioenergetic and biosynthetic function. Here, we review the possible connection between ER to mitochondria Ca²⁺ transfer and senescence. Understanding the pathways that contribute to senescence is essential to reveal new therapeutic targets that allow either delaying senescent cell accumulation or reduce senescent cell burden to alleviate multiple diseases.

Mitochondria and metabolic transitions in cardiomyocytes: lessons from development for stem cell-derived cardiomyocytes

Current methods to differentiate cardiomyocytes from human pluripotent stem cells (PSCs) inadequately recapitulate complete development and result in PSC-derived cardiomyocytes (PSC-CMs) with an immature or fetal-like phenotype. Embryonic and fetal development are highly dynamic periods during which the developing embryo or fetus is exposed to changing nutrient, oxygen, and hormone levels until birth. It is becoming increasingly apparent that these metabolic changes initiate developmental processes to mature cardiomyocytes. Mitochondria are central to these changes, responding to these metabolic changes and transitioning from small, fragmented mitochondria to large organelles capable of producing enough ATP to support the contractile function of the heart. These changes in mitochondria may not simply be a response to cardiomyocyte maturation; the metabolic signals that occur throughout development may actually be central to the maturation process in cardiomyocytes. Here, we review methods to enhance maturation of PSC-CMs and highlight evidence from development indicating the key roles that mitochondria play during cardiomyocyte maturation. We evaluate metabolic transitions that occur during development and how these affect molecular nutrient sensors, discuss how regulation of nutrient sensing pathways affect mitochondrial dynamics and function, and explore how changes in mitochondrial function can affect metabolite production, the cell cycle, and epigenetics to influence maturation of cardiomyocytes.

Diabetes, metabolic disease, and telomere length

Telomeres are regions of repetitive nucleotide sequences at the ends of chromosomes. Telomere length is a marker of DNA damage, which is often considered a biomarker for biological ageing, and has also been linked with cardiovascular disease, diabetes, and cancer. Emerging studies have highlighted the role of genetic and environmental factors, and explored the effect of modulating telomere length. We provide an overview of studies to date on diabetes and telomere length, and compare different methods and assays for evaluating telomere length and telomerase activity. We highlight the limitations of current studies and areas that warrant further research to unravel the link between diabetes and telomere length. The value of adding telomere length to clinical risk factors to improve risk prediction of diabetes and related complications also merits further investigation.

Control of Mesenchymal Stromal Cell Senescence by Tryptophan Metabolites

Cellular senescence contributes to aging and age-related disorders. High glucose (HG) induces mesenchymal stromal/stem cell (MSC) senescence, which hampers cell expansion and impairs MSC function. Intracellular HG triggers metabolic shift from aerobic glycolysis to oxidative phosphorylation, resulting in reactive oxygen species (ROS) overproduction. It causes mitochondrial dysfunction and morphological changes. Tryptophan metabolites such as 5-methoxytryptophan (5-MTP) and melatonin attenuate HG-induced MSC senescence by protecting mitochondrial integrity and function and reducing ROS generation. They upregulate the expression of antioxidant enzymes. Both metabolites inhibit stress-induced MSC senescence by blocking p38 MAPK signaling pathway, NF-κB, and p300 histone acetyltransferase activity. Furthermore, melatonin upregulates SIRT-1, which reduces NF-κB activity by de-acetylation of NF-κB subunits. Melatonin and 5-MTP are a new class of metabolites protecting MSCs against replicative and stress-induced cellular senescence. They provide new strategies to improve the efficiency of MSC-based therapy for diverse human diseases.

SGLT2i and GLP-1RA in Cardiometabolic and Renal Diseases: From Glycemic Control to Adipose Tissue Inflammation and Senescence

Background. Over the last few years, the use of sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP-1RA) has increased substantially in medical practice due to their documented benefits in cardiorenal and metabolic health. In this sense, and in addition to being used for glycemic control in diabetic patients, these drugs also have other favorable effects such as weight loss and lowering blood pressure, and more recently, they have been shown to have cardio and renoprotective effects with anti-inflammatory properties. Concerning the latter, the individual or associated use of these antihyperglycemic agents has been linked with a decrease in proinflammatory cytokines and with an improvement in the inflammatory profile in chronic endocrine-metabolic diseases. Hence, these drugs have been positioned as first-line therapy in the management of diabetes and its multiple comorbidities, such as obesity, which has been associated with persistent inflammatory states that induce dysfunction of the adipose tissue. Moreover, other frequent comorbidities in long-standing diabetic patients are chronic complications such as diabetic kidney disease, whose progression can be slowed by SGLT2i and/or GLP-1RA. The neuroendocrine and immunometabolism mechanisms underlying adipose tissue inflammation in individuals with diabetes and cardiometabolic and renal diseases are complex and not fully understood. Summary. This review intends to expose the probable molecular mechanisms and compile evidence of the synergistic or additive anti-inflammatory effects of SGLT2i and GLP-1RA and their potential impact on the management of patients with obesity and cardiorenal compromise.

The Impact of Pre-existing Comorbidities and Therapeutic Interventions on COVID-19

Evidence from the global outbreak of SARS-CoV-2 has clearly demonstrated that individuals with pre-existing comorbidities are at a much greater risk of dying from COVID-19. This is of great concern for individuals living with these conditions, and a major challenge for global healthcare systems and biomedical research. Not all comorbidities confer the same risk, however, many affect the function of the immune system, which in turn directly impacts the response to COVID-19. Furthermore, the myriad of drugs prescribed for these comorbidities can also influence the progression of COVID-19 and limit additional treatment options available for COVID-19. Here, we review immune dysfunction in response to SARS-CoV-2 infection and the impact of pre-existing comorbidities on the development of COVID-19. We explore how underlying disease etiologies and common therapies used to treat these conditions exacerbate COVID-19 progression. Moreover, we discuss the long-term challenges associated with the use of both novel and repurposed therapies for the treatment of COVID-19 in patients with pre-existing comorbidities.

Facial appearance and metabolic health biomarkers in women

Facial appearance has been suggested to provide an honest cue of an individual’s biological condition. However, there is little direct evidence that facial attractiveness reflects actual health. Here we tested if facial appearance is related with metabolic health biomarkers. Face photographs of 161 healthy, young women (M_age = 28.59, SD_age = 2.34) were assessed in terms of perceived attractiveness and health. Metabolic health was evaluated based on levels of markers of lipid and glucose metabolism balance, liver functioning, and inflammation. BMI, testosterone (T), and estradiol (E2) levels were controlled. Facial attractiveness, but not health, was negatively related with lipid profile components detrimental to health (total cholesterol, LDL, triglycerides) but not with relatively protective for health HDL. When controlled for BMI, E2, and T, only the relationship between attractiveness and triglycerides remained significant. Facial appearance was unrelated with glucose metabolism, liver functioning, and inflammatory markers. The results suggest, that for healthy women of reproductive age, such measures as BMI and sex hormone levels may be better predictors of attractiveness, compared to measures of metabolic health. Markers of lipid, glucose homeostasis, liver functioning or low-grade inflammation may be rather indicators of future health, of lesser importance in mating context, thus only modestly reflected in facial appearance.

Cellular Senescence as the Pathogenic Hub of Diabetes-Related Wound Chronicity

Diabetes is constantly increasing at a rate that outpaces genetic variation and approaches to pandemic magnitude. Skin cells physiology and the cutaneous healing response are progressively undermined in diabetes which predisposes to lower limb ulceration, recidivism, and subsequent lower extremities amputation as a frightened complication. The molecular operators whereby diabetes reduces tissues resilience and hampers the repair mechanisms remain elusive. We have accrued the notion that diabetic environment embraces preconditioning factors that definitively propel premature cellular senescence, and that ulcer cells senescence impair the healing response. Hyperglycemia/oxidative stress/mitochondrial and DNA damage may act as major drivers sculpturing the senescent phenotype. We review here historical and recent evidences that substantiate the hypothesis that diabetic foot ulcers healing trajectory, is definitively impinged by a self-expanding and self-perpetuative senescent cells society that drives wound chronicity. This society may be fostered by a diabetic archetypal secretome that induces replicative senescence in dermal fibroblasts, endothelial cells, and keratinocytes. Mesenchymal stem cells are also susceptible to major diabetic senescence drivers, which accounts for the inability of these cells to appropriately assist in diabetics wound healing. Thus, the use of autologous stem cells has not translated in significant clinical outcomes. Novel and multifaceted therapeutic approaches are required to pharmacologically mitigate the diabetic cellular senescence operators and reduce the secondary multi-organs complications. The senescent cells society and its adjunctive secretome could be an ideal local target to manipulate diabetic ulcers and prevent wound chronification and acute recidivism. This futuristic goal demands harnessing the diabetic wound chronicity epigenomic signature.

Type 2 diabetes is associated with the accumulation of senescent T cells

Type 2 diabetes is a global health priority, given that it is driven, in part, by an ageing population, the role of immune senescence has been overlooked. This is surprising, as the functional impairments of senescent T cells show strong similarities to patients with hyperglycaemia. Immune senescence is typified by alterations in T cell memory, such as the accumulation of highly differentiated end‐stage memory T cells, as well as a constitutive low‐grade inflammation, which drives further immune differentiation. We show here in a preliminary study that people living with type 2 diabetes have a higher circulating volume of senescent T cells accompanied with a higher level of systemic inflammation. This inflammatory environment drives the expression of a unique array of chemokine receptors on senescent T cells, most notably C‐X‐C motif chemokine receptor type 2. However, this increased expression of migratory markers does not translate to improved extravasation owing to a lack of glucose uptake by the T cells. Our results therefore demonstrate that the presence of senescent T cells has a detrimental impact on immune function during type 2 diabetes.

The impact of concurrent HIV and type II diabetes on immune maturation, immune regulation and immune activation

Chronic immune activation and inflammation are constant findings in people living with HIV (PLWH) and contribute to the risk of non-AIDS-related morbidities, including cardiovascular diseases (CVD). Type 2 diabetes (T2D) is also characterized by immune activation and inflammation. We aimed to investigate the impact of concurrent HIV infection and T2D on T-cell subsets. The study included PLWH with T2D (HIV+T2D+, N = 25) and without T2D (HIV+T2D-, N = 25) and HIV-negative controls with T2D (HIV-T2D+, N = 22) and without T2D (HIV-T2D-, N = 28). All PLWH in the study were receiving combination antiretroviral therapy. We examined T-cell homeostasis by determining T-cell subsets (immune maturation, immune regulation and immune activation) using flow cytometry. HIV+T2D- had lower proportion of Tc17 cells and higher proportion of apoptotic cells than HIV-T2D-. When comparing HIV+T2D+ and HIV+T2D- a lower proportion of CD4+ recent thymic emigrants (RTE) was found (p = 0.028). Furthermore, HIV+T2D+ had a higher proportion of non-suppressive CD4+ Tregs compared to HIV+T2D- (p = 0.010). In conclusion, even in the setting of treated HIV infection, distinct immunological alterations are found. In PLWH with concomitant T2D, most alterations in T-cell subsets were related to HIV and only few differences were found between PLWH with and without diabetes.

Inhibition of the sodium-glucose co-transporter 2 in the elderly: clinical and mechanistic insights into safety and efficacy

The prevalence of type 2 diabetes mellitus (T2DM) in the elderly grew sharply over the last decade. Reduced insulin sensitivity and secretory capacity, weight gain, sarcopenia, and elevated adiposity are all common metabolic and body changes in the aging population that favor an increased risk of hypoglycemia, frailty syndrome, falls, and cognitive dysfunction. First line antidiabetic therapy is frequently not safe in older individuals because of its high risk of hypoglycemia and prevalent co-morbid diseases, such as chronic kidney disease, osteoporosis, cardiovascular disease, and obesity. Sodium-glucose cotransporter 2 inhibitor (SGLT2i) is a new class of antidiabetic therapy that inhibits glucose and sodium reabsorption on renal proximal convoluted tubule. Its effect is well demonstrated in various clinical scenarios in the younger population. This review and metanalysis describe particularities of the SGLT2i on the elderly, with mechanistic insights of the potential benefit and remaining challenges about the use of these drugs in this important age group. Further, we will present a meta-analysis of the main effects of SGLT2i reported in post-hoc studies in which the median age of the subgroups analyzed was over 60 years. Despite the absence of specific clinical trials for this population, our findings suggest that SGLT2i therapy on older individuals is effective to lower glucose and maintain its effect on systolic blood pressure and body weight.

Urothelial Senescence in the Pathophysiology of Diabetic Bladder Dysfunction-A Novel Hypothesis

Diabetic bladder dysfunction (DBD) is a well-recognized and common symptom affecting up to 50% of all diabetic patients. DBD has a broad range of clinical presentations ranging from overactive to underactive bladder symptoms that develops in middle-aged to elderly patients with long standing and poorly controlled diabetes. Low efficacy of current therapeutics and lifestyle interventions combined with high national healthcare costs highlight the need for more research into bladder dysfunction pathophysiology and novel treatment options. Cellular senescence is an age-related physiologic process in which cells undergo irreversible growth arrest induced by replicative exhaustion and damaging insults. While controlled senescence negatively regulates cell proliferation and promotes tissue regeneration, uncontrolled senescence is known to result in tissue dysfunction through enhanced secretion of inflammatory factors. This review presents previous scientific findings and current hypotheses that characterize diabetic bladder dysfunction. Further, we propose the novel hypothesis that cellular senescence within the urothelial layer of the bladder contributes to the pro-inflammatory/pro-oxidant environment and symptoms of diabetic bladder dysfunction. Our results show increased cellular senescence in the urothelial layer of the bladder; however, whether this phenomenon is the cause or effect of DBD is unknown. The urothelial layer of the bladder is made up of transitional epithelia specialized to contract and expand with demand and plays an active role in transmission by modulating afferent activity. Transition from normal functioning urothelial cells to secretory senescence cells would not only disrupt the barrier function of this layer but may result in altered signaling and sensation of bladder fullness; dysfunction of this layer is known to result in symptoms of frequency and urgency. Future DBD therapeutics may benefit from targeting and preventing early transition of urothelial cells to senescent cells.

Sulforaphane Delays Fibroblast Senescence by Curbing Cellular Glucose Uptake, Increased Glycolysis, and Oxidative Damage

Increased cell senescence contributes to the pathogenesis of aging and aging-related disease. Senescence of human fibroblasts in vitro may be delayed by culture in low glucose concentration. There is also accumulating evidence of senescence delay by exposure to dietary bioactive compounds that activate transcription factor Nrf2. The mechanism of cell senescence delay and connection between these responses is unknown. We describe herein that the cruciferous vegetable-derived metabolite, sulforaphane (SFN), activates Nrf2 and delays senescence of human MRC-5 and BJ fibroblasts in vitro. Cell senescence is associated with a progressive and marked increased rate of glucose metabolism through glycolysis. This increases mitochondrial dysfunction and overwhelms defences against reactive metabolites, leading to increasing proteomic and genomic oxidative damage. Increased glucose entry into glycolysis in fibroblast senescence is mainly mediated by increased hexokinase-2. SFN delayed senescence by decreasing glucose metabolism on the approach to senescence, exhibiting a caloric restriction mimetic-like activity and thereby decreased oxidative damage to cell protein and DNA. This was associated with increased expression of thioredoxin-interacting protein, curbing entry of glucose into cells; decreased hexokinase-2, curbing entry of glucose into cellular metabolism; decreased 6-phosphofructo-2-kinase, downregulating formation of allosteric enhancer of glycolysis fructose-2,6-bisphosphate; and increased glucose-6-phosphate dehydrogenase, downregulating carbohydrate response element- (ChRE-) mediated transcriptional enhancement of glycolysis by Mondo/Mlx. SFN also enhanced clearance of proteins cross-linked by transglutaminase which otherwise increased in senescence. This suggests that screening of compounds to counter senescence-associated glycolytic overload may be an effective strategy to identify compounds with antisenescence activity and health beneficial effects of SFN in longevity may involve delay of senescence through glucose and glycolytic restriction response.

With Great Age Comes Great Metastatic Ability: Ovarian Cancer and the Appeal of the Aging Peritoneal Microenvironment

Age is one of the biggest risk factors for ovarian cancer. Older women have higher rates of diagnosis and death associated with the disease. In mouse models, it was shown that aged mice had greater tumor burden than their younger counterparts when intraperitoneally injected with ovarian tumor cells. While very few papers have been published looking at the direct link between ovarian cancer metastasis and age, there is a wealth of information on how age affects metastatic microenvironments. Mesothelial cells, the peritoneal extracellular matrix (ECM), fibroblasts, adipocytes and immune cells all exhibit distinct changes with age. The aged peritoneum hosts a higher number of senescent cells than its younger counterpart, in both the mesothelium and the stroma. These senescent cells promote an inflammatory profile and overexpress Matrix Metalloproteinases (MMPs), which remodel the ECM. The aged ECM is also modified by dysregulated collagen and laminin synthesis, increases in age-related crosslinking and increasing ovarian cancer invasion into the matrix. These changes contribute to a vastly different microenvironment in young and aged models for circulating ovarian cancer cells, creating a more welcoming “soil”.

Induction and Validation of Cellular Senescence in Primary Human Cells

Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a hallmark of various pathophysiological conditions including tumor suppression, tissue remodeling and aging. The inducers of cellular senescence in vivo are still poorly characterized. However, a number of stimuli can be used to promote cellular senescence ex vivo. Among them, most common senescence-inducers are replicative exhaustion, ionizing and non-ionizing radiation, genotoxic drugs, oxidative stress, and demethylating and acetylating agents. Here, we will provide detailed instructions on how to use these stimuli to induce fibroblasts into senescence. This protocol can easily be adapted for different types of primary cells and cell lines, including cancer cells. We also describe different methods for the validation of senescence induction. In particular, we focus on measuring the activity of the lysosomal enzyme Senescence-Associated β-galactosidase (SA-β-gal), the rate of DNA synthesis using 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, the levels of expression of the cell cycle inhibitors p16 and p21, and the expression and secretion of members of the Senescence-Associated Secretory Phenotype (SASP). Finally, we provide example results and discuss further applications of these protocols.

The role of cellular senescence in aging through the prism of Koch-like criteria

Since Hayflick's discovery of cellular senescence (CS), a great volume of knowledge in the field has been accumulated and intensively discussed. Here, we attempted to organize the evidence "for" and "against" the hypothesized causal role of CS in aging. For that purpose, we utilized robust Koch-like logical criteria, based on the assumption that some quantitative relationships between the accumulation of senescent cells and aging rate should exist. If so, it could be expected that (i) the "CS load" would be greater in the premature aging phenotype and lesser in longevity phenotype; (ii) CS would promote age-related diseases, and (iii) the interventions that modulate the levels of senescent cells should also modulate health/lifespan. The analysis shows that CS can be considered a causal factor of aging and an important player in various age-related diseases, though its contribution may greatly vary across species. While the relative impact of senescent cells to aging could overall be rather limited and their elimination is hardly expected to be the "fountain of youth", the potential benefits of the senolytic strategy seems a promising option in combating age-related diseases and extending healthspan.

Strategies to retain properties of bone marrow-derived mesenchymal stem cells ex vivo

Mesenchymal stem cells (MSCs) have been extensively used for cell therapies and tissue engineering. The current MSC strategy requires a large quantity of cells for such applications, which can be achieved through cell expansion in culture. In the body, stem cell fate is largely determined by their microenvironment, known as the niche. The complex and dynamic stem cell niche provides physical, mechanical, and chemical cues to collaboratively regulate cell activities. It remains a great challenge to maintain the properties of MSCs in culture. Constructing a microenvironment as an engineered stem cell niche in culture to maintain MSC phenotypes, properties, and functions is a viable strategy to address the issue. Here, we review the current understanding of MSC behavior in the bone marrow niche, describe different strategies to engineer an in vitro microenvironment for maintaining MSC properties and functions, and discuss previous findings on environmental factors critical to the modulation of MSC activities in engineered microenvironments.

Treatment of diabetic mice with the SGLT2 inhibitor TA-1887 antagonizes diabetic cachexia and decreases mortality

A favorable effect of an inhibitor of the sodium–glucose cotransporter 2 (SGLT2i) on mortality of diabetic patients was recently reported, although mechanisms underlying that effect remained unclear. Here, we examine SGLT2i effects on survival of diabetic mice and assess factors underlying these outcomes. To examine SGLT2i treatment effects in a model of severe diabetes, we fed genetically diabetic db/db mice a high-fat diet and then assessed outcomes including diabetic complications between SGLT2i TA-1887-treated and control mice. We also compare effects of SGLT2i TA-1887 with those of lowering blood glucose levels via insulin treatment. Untreated db/db mice showed remarkable weight loss, or cachexia, while TA-1887-treated mice did not but rather continued to gain weight at later time points and decreased mortality. TA-1887 treatment prevented pancreatic beta cell death, enhanced preservation of beta cell mass and endogenous insulin secretion, and increased insulin sensitivity. Moreover, TA-1887 treatment attenuated inflammation, oxidative stress, and cellular senescence, especially in visceral white adipose tissue, and antagonized endothelial dysfunction. Insulin treatment of db/db mice also prevented weight loss and antagonized inflammation and oxidative stress. However, insulin treatment had less potent effects on survival and prevention of cellular senescence and endothelial dysfunction than did TA-1887 treatment. SGLT2i treatment prevents diabetic cachexia and death by preserving function of beta cells and insulin target organs and attenuating complications. SGLT2i treatment may be a promising therapeutic strategy for type 2 diabetes patients with morbid obesity and severe insulin resistance.

Sodium-glucose cotransporter 2 inhibitor (SGLT2i) has a favorable effect on mortality of diabetic subjects, but the mechanism stays unclear. Taichi Sugizaki at Kumamoto University examined SGLT2i effects in severe diabetic obese mice, and discovered that they showed prolonged survival without pathological weight loss, or cachexia. As with SGLT2i, Insulin also prevented cachexia, improved pancreatic beta cell function, insulin sensitivity and some organ damages. However, what makes SGLT2i important was to suppress cellular aging or vessel inflammation, while insulin accelerated those developments, which may lead to a result that SGLT2i has contributed to prolonged survival more than insulin. SGLT2i demonstrates an association with survival period upon maintaining good condition of pancreatic beta cells and insulin target organs, providing insight into strategies for treatment of severe diabetes.

Concise Review: Challenges in Regenerating the Diabetic Heart: A Comprehensive Review

Stem cell therapy is one of the promising regenerative strategies developed to improve cardiac function in patients with ischemic heart diseases (IHD). However, this approach is limited in IHD patients with diabetes due to a progressive decline in the regenerative capacity of stem cells. This decline is mainly attributed to the metabolic memory incurred by diabetes on stem cell niche and their systemic cues. Understanding the molecular pathways involved in the diabetes-induced deterioration of stem cell function will be critical for developing new cardiac regeneration therapies. In this review, we first discuss the most common molecular alterations occurring in the diabetic stem cells/progenitor cells. Next, we highlight the key signaling pathways that can be dysregulated in a diabetic environment and impair the mobilization of stem/progenitor cells, which is essential for the transplanted/endogenous stem cells to reach the site of injury. We further discuss the possible methods of preconditioning the diabetic cardiac progenitor cell (CPC) with an aim to enrich the availability of efficient stem cells to regenerate the diseased diabetic heart. Finally, we propose new modalities for enriching the diabetic CPC through genetic or tissue engineering that would aid in developing autologous therapeutic strategies, improving the proliferative, angiogenic, and cardiogenic properties of diabetic stem/progenitor cells. Stem Cells 2017;35:2009-2026.

Effect of local hIL-10 gene therapy on experimental periodontitis in ovariectomized rats

OBJECTIVE

To investigate the effect of local hIL-10 gene therapy on experimental periodontitis in rats and to elucidate the mechanism underlying this effect.

MATERIAL AND METHODS

Experimental periodontitis was induced in ovariectomized (OVX) rats using a silk ligature. We then injected 5 μg of hIL-10 plasmid with 5 μl of liposomes or 5 μg of vector plasmid with 5 μl of liposomes into the palatal side of the gingival mucosa of the upper left second molar once every two days. The rats were killed 48 hours after the seventh injection. The body weight; bone mineral density of the whole body, pelvis and spine; resorption of the alveolar bone; and number of cytokine-positive cells were measured to determine the effects of hIL-10 on the periodontal tissue.

RESULTS

hIL-10 was expressed in periodontal tissues after local gene delivery. The expressed hIL-10 protein inhibited alveolar bone resorption and downregulated IL-1β, IL-6, TNF-α, RANKL and MMP-8 in the periodontal ligament in the root furcation region.

CONCLUSIONS

Local hIL-10 gene transfer suppressed alveolar bone resorption in OVX rats, and this effect was probably associated with the decline in the expression of pro-inflammatory cytokines in the periodontal tissues.

Resveratrol Protects against High-Fat Diet Induced Renal Pathological Damage and Cell Senescence by Activating SIRT1

Obesity-related renal diseases have been a worldwide issue. Effective strategy that prevents high fat-diet induced renal damage is of great significance. Resveratrol, a natural plant polyphenol, is famous for its antioxidant activity, cardioprotective effects and anticancer properties. However whether resveratrol can play a role in the treatment of renal diseases is unknown. In this study, we added resveratrol in normal glucose or high glucose medium and provide evidences that resveratrol protects against high-glucose triggered oxidative stress and cell senescence. Moreover, mice were fed with standard diet, standard diet plus resveratrol, high-fat diet or high-fat diet plus resveratrol for 3 months, and results show that resveratrol treatment prevents high-fat diet induced renal pathological damage by activating SIRT1, a key member in the mammalian sirtuin family that response to calorie restriction life-extension method. This research confirms the potential role of resveratrol in the treatment of renal diseases and may provide an effective and convenient method to mimic the beneficial effects of calorie restriction.

Umbilical cord-derived mesenchymal stromal cell-conditioned medium exerts in vitro antiaging effects in human fibroblasts

BACKGROUND AIMS

Chronic wounds are a common complication of diabetes. Fibroblast-myofibroblast differentiation is important for wound repair, which is commonly impaired in non-healing wounds, and the underlying mechanisms need to be further elucidated.

METHODS

We used high glucose (HG) to simulated the diabetes microenvironment and explored its effects on the biological features of fibroblasts in vitro.

RESULTS

The results showed that prolonged HG induced senescence in fibroblasts through activation of p21 and p16 in a reactive oxygen species (ROS)-dependent manner, further delayed the viability and migration in fibroblasts and also depressed fibroblast differentiation through the TGF-β/Smad signaling pathway. However, mesenchymal stromal cell-conditioned medium (MSC-CM) counteracts the effects of HG. Treatment of fibroblasts with MSC-CM decreased HG-induced ROS overproduction, ameliorated HG-induced senescence in fibroblasts and reversed the defects in myofibroblast formation. Our results may provide clues for the pathogenesis of chronic wounds and a theoretical basis to develop MSC-CM as an alternative therapeutic method to treatment of chronic wounds.

Disc cell senescence in intervertebral disc degeneration: Causes and molecular pathways

The accumulation of senescent disc cells in degenerative intervertebral disc (IVD) suggests the detrimental roles of cell senescence in the pathogenesis of intervertebral disc degeneration (IDD). Disc cell senescence decreased the number of functional cells in IVD. Moreover, the senescent disc cells were supposed to accelerate the process of IDD via their aberrant paracrine effects by which senescent cells cause the senescence of neighboring cells and enhance the matrix catabolism and inflammation in IVD. Thus, anti-senescence has been proposed as a novel therapeutic target for IDD. However, the development of anti-senescence therapy is based on our understanding of the molecular mechanism of disc cell senescence. In this review, we focused on the molecular mechanism of disc cell senescence, including the causes and various molecular pathways. We found that, during the process of IDD, age-related damages together with degenerative external stimuli activated both p53-p21-Rb and p16-Rb pathways to induce disc cell senescence. Meanwhile, disc cell senescence was regulated by multiple signaling pathways, suggesting the complex regulating network of disc cell senescence. To understand the mechanism of disc cell senescence better contributes to developing the anti-senescence-based therapies for IDD.

Senescence associated secretory phenotype profile from primary lung mice fibroblasts depends on the senescence induction stimuli

Cellular senescence is a multifactorial phenomenon of growth arrest and distorted function, which has been recognized as an important feature during tumor suppression mechanisms and a contributor to aging. Senescent cells have an altered secretion pattern called Senescence-Associated Secretory Phenotype (SASP) that comprises a complex mix of factors including cytokines, growth factors, chemokines, and matrix metalloproteinases. SASP has been related with local inflammation that leads to cellular transformation and neurodegenerative diseases. Various pathways for senescence induction have been proposed; the most studied is replicative senescence due to telomere attrition called replicative senescence (RS). However, senescence can be prematurely achieved when cells are exposed to diverse stimuli such as oxidative stress (stress-induced premature senescence, SIPS) or proteasome inhibition (proteasome inhibition-induced premature senescence, PIIPS). SASP has been characterized in RS and SIPS but not in PIIPS. Hence, our aim was to determine SASP components in primary lung fibroblasts obtained from CD-1 mice induced to senescence by PIIPS and compare them to RS and SIPS. Our results showed important variations in the 62 cytokines analyzed, while SIPS and RS showed an increase in the secretion of most cytokines, and in PIIPS only 13 were incremented. Variations in glutathione-redox balance were also observed in SIPS and RS, and not in PIIPS. All senescence types SASP displayed a pro-inflammatory profile and increased proliferation in L929 mice fibroblasts exposed to SASP. However, the behavior observed was not exactly the same, suggesting that the senescence induction pathway might encompass dissimilar responses in adjacent cells and promote different outcomes.

Growth Hormone Receptor Antagonist Transgenic Mice Have Increased Subcutaneous Adipose Tissue Mass, Altered Glucose Homeostasis and No Change in White Adipose Tissue Cellular Senescence

BACKGROUND

Growth hormone (GH)-resistant/deficient mice experience improved glucose homeostasis and substantially increased lifespan. Recent evidence suggests that long-lived GH-resistant/deficient mice are protected from white adipose tissue (WAT) dysfunction, including WAT cellular senescence, impaired adipogenesis and loss of subcutaneous WAT in old age. This preservation of WAT function has been suggested to be a potential mechanism for the extended lifespan of these mice.

OBJECTIVE

The objective of this study was to examine WAT senescence, WAT distribution and glucose homeostasis in dwarf GH receptor antagonist (GHA) transgenic mice, a unique mouse strain having decreased GH action but normal longevity.

METHODS

18-month-old female GHA mice and wild-type (WT) littermate controls were used. Prior to dissection, body composition, fasting blood glucose as well as glucose and insulin tolerance tests were performed. WAT distribution was determined by weighing four distinct WAT depots at the time of dissection. Cellular senescence in four WAT depots was assessed using senescence-associated β-galactosidase staining to quantify the senescent cell burden, and real-time qPCR to quantify gene expression of senescence markers p16 and IL-6.

RESULTS

GHA mice had a 22% reduction in total body weight, a 33% reduction in lean mass and a 10% increase in body fat percentage compared to WT controls. GHA mice had normal fasting blood glucose and improved insulin sensitivity; however, they exhibited impaired glucose tolerance. Moreover, GHA mice displayed enhanced lipid storage in the inguinal subcutaneous WAT depot (p < 0.05) and a 1.7-fold increase in extra-/intraperitoneal WAT ratio compared to controls (p < 0.05). Measurements of WAT cellular senescence showed no difference between GHA mice and WT controls.

CONCLUSIONS

Similar to other mice with decreased GH action, female GHA mice display reduced age-related lipid redistribution and improved insulin sensitivity, but no change in cellular senescence. The similar abundance of WAT senescent cells in GHA and control mice suggests that any protection against generation of senescent cells afforded by decreased GH action, low insulin-like growth factor 1 and/or improved insulin sensitivity in the GHA mice may be offset by their severe adiposity, since obesity is known to increase senescence.

Cellular Senescence in Type 2 Diabetes: A Therapeutic Opportunity

Cellular senescence is a fundamental aging mechanism that has been implicated in many age-related diseases and is a significant cause of tissue dysfunction. Accumulation of senescent cells occurs during aging and is also seen in the context of obesity and diabetes. Senescent cells may play a role in type 2 diabetes pathogenesis through direct impact on pancreatic β-cell function, senescence-associated secretory phenotype (SASP)-mediated tissue damage, and involvement in adipose tissue dysfunction. In turn, metabolic and signaling changes seen in diabetes, such as high circulating glucose, altered lipid metabolism, and growth hormone axis perturbations, can promote senescent cell formation. Thus, senescent cells might be part of a pathogenic loop in diabetes, as both a cause and consequence of metabolic changes and tissue damage. Therapeutic targeting of a basic aging mechanism such as cellular senescence may have a large impact on disease pathogenesis and could be more effective in preventing the progression of diabetes complications than currently available therapies that have limited impact on already existing tissue damage. Therefore, senescent cells and the SASP represent significant opportunities for advancement in the prevention and treatment of type 2 diabetes and its complications.

Disentangling the effects of circulating IGF-1, glucose, and cortisol on features of perceived age

Circulatory levels of insulin-like growth factor (IGF-1), glucose, and cortisol have been previously associated with facial aging. However, as these serum measures are related, it is unclear whether their associations with skin aging occur independently from each other. We aimed to investigate whether the associations between serum IGF-1, glucose, and cortisol levels and perceived age/wrinkle grade occur independently of each other and whether these are mediated via skin wrinkling or via other skin aging features. Perceived age and skin wrinkling grade were assessed in a random sample from the Leiden Longevity Study with non-fasted (N = 579) and fasted blood sampling (N = 219). In our study population, a higher non-fasted IGF-1 level was associated with a lower skin wrinkling grade (p value = 0.014) and tended to associate with a lower perceived age (p value = 0.067), which was mediated for approximately 100 % by skin wrinkling. A higher non-fasted glucose level was associated with a higher perceived age (p value = 0.017), which was mediated for 51 % by skin wrinkling grade (p value = 0.112). A higher fasted cortisol level tended to associate with a higher perceived age (p value = 0.116), which was mediated for 29 % by skin wrinkling. Results remained similar when the serum measures were statistically adjusted for each other. Thus, the previously reported serum measures associate independently from each other with skin aging. IGF-1 is predominantly associated with perceived age by skin wrinkling, whereas cortisol and glucose also by other skin aging features.

Growth hormone action predicts age-related white adipose tissue dysfunction and senescent cell burden in mice

The aging process is associated with the development of several chronic diseases. White adipose tissue (WAT) may play a central role in age-related disease onset and progression due to declines in adipogenesis with advancing age. Recent reports indicate that the accumulation of senescent progenitor cells may be involved in age-related WAT dysfunction. Growth hormone (GH) action has profound effects on adiposity and metabolism and is known to influence lifespan. In the present study we tested the hypothesis that GH activity would predict age-related WAT dysfunction and accumulation of senescent cells. We found that long-lived GH-deficient and -resistant mice have reduced age-related lipid redistribution. Primary preadipocytes from GH-resistant mice also were found to have greater differentiation capacity at 20 months of age when compared to controls. GH activity was also found to be positively associated with senescent cell accumulation in WAT. Our results demonstrate an association between GH activity, age-related WAT dysfunction, and WAT senescent cell accumulation in mice. Further studies are needed to determine if GH is directly inducing cellular senescence in WAT or if GH actions on other target organs or alternative downstream alterations in insulin-like growth factor-1, insulin or glucose levels are responsible.

The influence of the telomere-telomerase system on diabetes mellitus and its vascular complications

INTRODUCTION

The telomere-telomerase system plays an important role in the pathogenesis and disease progression of diabetes mellitus as well as in its vascular complications. Recent studies suggest that telomere shortening and abnormal telomerase activity occur in patients with diabetes mellitus, and targeting the telomere-telomerase system has become a prospective treatment for diabetes mellitus and its vascular complications. This review highlights the significance of the telomere-telomerase system and supports its role as a possible therapeutic target for patients with diabetes mellitus and its vascular complications Areas covered: This review covers the advances in understanding the telomere-telomerase system over the last 30 years and its significance in diabetes mellitus. In addition, it provides knowledge regarding the significance of the telomere-telomerase system in diabetes mellitus and its vascular complications as well as its role and mechanisms in oxidative stress, cell therapy and antioxidant activity Expert opinion: The telomere-telomerase system may be a potential therapeutic target that can protect against DNA damage and apoptosis in patients with diabetes mellitus and its vascular complications. DNA damage and apoptosis are associated with oxidative stress and are involved in the dysfunction of pancreatic β cells, insulin resistance, and its vascular complications. Abnormalities in the telomere-telomerase system may be associated with diabetes mellitus and its vascular complications. Therapies targeting telomere-telomerase system, telomerase reverse transcriptase transfection and alterative telomere lengthening must be identified before gene therapy can commence.

Extra-nuclear telomerase reverse transcriptase (TERT) regulates glucose transport in skeletal muscle cells

Telomerase reverse transcriptase (TERT) is a key component of the telomerase complex. By lengthening telomeres in DNA strands, TERT increases senescent cell lifespan. Mice that lack TERT age much faster and exhibit age-related conditions such as osteoporosis, diabetes and neurodegeneration. Accelerated telomere shortening in both human and animal models has been documented in conditions associated with insulin resistance, including T2DM. We investigated the role of TERT, in regulating cellular glucose utilisation by using the myoblastoma cell line C2C12, as well as primary mouse and human skeletal muscle cells. Inhibition of TERT expression or activity by using siRNA (100nM) or specific inhibitors (100nM) reduced basal 2-deoxyglucose uptake by ~50%, in all cell types, without altering insulin responsiveness. In contrast, TERT over-expression increased glucose uptake by 3.25-fold. In C2C12 cells TERT protein was mostly localised intracellularly and stimulation of cells with insulin induced translocation to the plasma membrane. Furthermore, co-immunoprecipitation experiments in C2C12 cells showed that TERT was constitutively associated with glucose transporters (GLUTs) 1, 4 and 12 via an insulin insensitive interaction that also did not require intact PI3-K and mTOR pathways. Collectively, these findings identified a novel extra-nuclear function of TERT that regulates an insulin-insensitive pathway involved in glucose uptake in human and mouse skeletal muscle cells.