Regulation of p27 and cdk2 expression in different adipose tissue depots in aging and obesity

Aging usually comes associated with increased visceral fat accumulation, reaching even an obesity state, and favoring its associated comorbidities. One of the processes involved in aging is cellular senescence, which is highly dependent on the activity of the regulators of the cell cycle. The aim of this study was to analyze the changes in the expression of p27 and cdk2 in different adipose tissue depots during aging, as well as their regulation by obesity in mice. Changes in the expression of p27 and CDK2 in visceral and subcutaneous white adipose tissue (WAT) biopsies were also analyzed in a human cohort of obesity and type 2 diabetes. p27, but not cdk2, exhibits a lower expression in subcutaneous than in visceral WAT in mice and humans. p27 is drastically downregulated by aging in subcutaneous WAT (scWAT), but not in gonadal WAT, of female mice. Obesity upregulates p27 and cdk2 expression in scWAT, but not in other fat depots of aged mice. In humans, a significant upregulation of p27 was observed in visceral WAT of subjects with obesity. Taken together, these results show a differential adipose depot-dependent regulation of p27 and cdk2 in aging and obesity, suggesting that p27 and cdk2 could contribute to the adipose-tissue depot’s metabolic differences. Further studies are necessary to fully corroborate this hypothesis

Changes in brown adipose tissue lipid mediator signatures with aging, obesity, and DHA supplementation in female mice

Brown adipose tissue (BAT) dysfunction in aging and obesity has been related to chronic unresolved inflammation, which could be mediated by an impaired production of specialized proresolving lipid mediators (SPMs), such as Lipoxins-LXs, Resolvins-Rvs, Protectins-PDs, and Maresins-MaRs. Our aim was to characterize the changes in BAT SPMs signatures and their association with BAT dysfunction during aging, especially under obesogenic conditions, and their modulation by a docosahexaenoic acid (DHA)-rich diet. Lipidomic, functional, and molecular studies were performed in BAT of 2-and 18-month- old lean (CT) female mice and in 18-month- old diet-induced obese (DIO) mice fed with a high-fat diet (HFD), or a DHA-enriched HFD. Aging downregulated Prdm16 and UCP1 levels, especially in DIO mice, while DHA partially restored them. Arachidonic acid (AA)-derived LXs and DHA-derived MaRs and PDs were the most abundant SPMs in BAT of young CT mice.Interestingly, the sum of LXs and of PDs were significantly lower in aged DIO mice compared to young CT mice. Some of the SPMs most significantly reduced in obese-aged mice included LXB4, MaR2, 4S,14S-diHDHA, 10S,17S-diHDHA (a.k.a. PDX), and RvD6. In contrast, DHA increased DHA-derived SPMs, without modifying LXs. However, MicroPET studies showed that DHA was not able to counteract the impaired cold exposure response in BAT of obese-aged mice. Our data suggest that a defective SPMs production could underlie the decrease of BAT activity observed in obese-aged mice, and highlight the relevance to further characterize the physiological role and therapeutic potential of specific SPMs on BAT development and function

Effects of DHA supplementation and physical exercise on adipose tissue and metabolic health: studies in aged obese female mice and postmenopausal women

Adipose tissue is a dynamic organ that contributes to maintain whole-body metabolic status. Three major types of adipose tissue/cells, white, brown, and beige, can be found. All of them become dysfunctional in obesity and in aging, with brown and beige showing a declined activity. Importantly, both obesity and aging are associated to a chronic, low-grade inflammation that underlies the adipose tissue dysfunction and the development of the associated comorbidities. In this context, aging obese women represent a target population for preventive strategies, since aging and obesity-pathophysiological processes are accelerated due to menopause. In this background, docosahexaenoic acid (DHA), probably through its derived specialized proresolving lipid mediators (SPMs), as well as exercise training, via its beneficial effects in several metabolic organs, could be therapeutic approaches for aging and obesity. Hence, we hypothesized that DHA supplementation and/or exercise training could ameliorate adipose tissue dysfunction in aged obese female mice, and in postmenopausal women with overweight/obesity, also reducing biomarkers of metabolic disturbances. With this aim, the first experimental study was based on long-term DHA dietary supplementation or exercise training, conducted in diet-induced obese mice from adulthood up to 18 months of age, to study the effects on subcutaneous white adipose tissue (scWAT) and interscapular brown adipose tissue (iBAT). Thereafter, a randomized clinical trial was conducted in postmenopausal women with overweight/obesity, to explore the effects of DHA supplementation and/or resistance training (RT), on body composition and metabolic biomarkers, as well as in the systemic-adipose inflammatory axis. The animal studies revealed actions for DHA on improving scWAT metabolic and inflammatory status (Chapter 1), including a reduction in adipocytes size, the downregulation of lipogenic and inflammatory genes, the upregulation of antiinflammatory M2 macrophages, and the induction of beige adipocyte genes. On iBAT, obesity and aging induced a reduction in SPMs content, which could contribute to its proinflammatory status and reduced thermogenic function (Chapter 2). The DHA-enriched diet increased UCP1 levels and n-3 PUFA derived SPMs in iBAT, without recovering its impaired response to cold. Concerning the effects of long-term exercise in obese aged mice (Chapter 3), the scWAT showed an increase in fatty acid oxidation and a reduction in inflammatory genes, lower macrophage infiltration, and an increment in thermogenic and beige adipocytes genes. However, the iBAT was less responsive to exercise, revealing only a moderate stimulation of thermogenic genes/proteins. Importantly, the effects on scWAT and iBAT could contribute to the observed systemic effects exerted by DHA, which reduced total and LDL-cholesterol, and of exercise, which improved insulin resistance and glucose tolerance. Finally, the clinical trial in postmenopausal women with overweight/obesity (Chapters 4, 5), revealed that DHA supplementation induced lower diastolic blood pressure, inflammatory platelet-to-lymphocyte ratio, and circulating triglycerides. On the other hand, RT induced local fat mass losses and muscle mass gains, maintained whole-body bone mineral content and improved glucose tolerance and scWAT ADIPONECTIN expression. Both interventions reduced circulating C-reactive protein and scWAT mRNA levels of adipocytokines (LEPTIN, CHEMERIN, IL6) and M1 macrophages markers (CD11c). The combination of both treatments did not have any relevant synergistic effect. Overall, this research provides evidence that DHA supplementation and exercise training induce a beneficial remodeling of adipose tissue that could contribute to prevent the systemic inflammation and comorbidities of obesity and aging

Effects of DHA supplementation and physical exercise on adipose tissue and metabolic health: studies in aged obese female mice and postmenopausal women

Adipose tissue is a dynamic organ that contributes to maintain whole-body metabolic status. Three major types of adipose tissue/cells, white, brown, and beige, can be found. All of them become dysfunctional in obesity and in aging, with brown and beige showing a declined activity. Importantly, both obesity and aging are associated to a chronic, low-grade inflammation that underlies the adipose tissue dysfunction and the development of the associated comorbidities. In this context, aging obese women represent a target population for preventive strategies, since aging and obesity-pathophysiological processes are accelerated due to menopause. In this background, docosahexaenoic acid (DHA), probably through its derived specialized proresolving lipid mediators (SPMs), as well as exercise training, via its beneficial effects in several metabolic organs, could be therapeutic approaches for aging and obesity. Hence, we hypothesized that DHA supplementation and/or exercise training could ameliorate adipose tissue dysfunction in aged obese female mice, and in postmenopausal women with overweight/obesity, also reducing biomarkers of metabolic disturbances. With this aim, the first experimental study was based on long-term DHA dietary supplementation or exercise training, conducted in diet-induced obese mice from adulthood up to 18 months of age, to study the effects on subcutaneous white adipose tissue (scWAT) and interscapular brown adipose tissue (iBAT). Thereafter, a randomized clinical trial was conducted in postmenopausal women with overweight/obesity, to explore the effects of DHA supplementation and/or resistance training (RT), on body composition and metabolic biomarkers, as well as in the systemic-adipose inflammatory axis. The animal studies revealed actions for DHA on improving scWAT metabolic and inflammatory status (Chapter 1), including a reduction in adipocytes size, the downregulation of lipogenic and inflammatory genes, the upregulation of antiinflammatory M2 macrophages, and the induction of beige adipocyte genes. On iBAT, obesity and aging induced a reduction in SPMs content, which could contribute to its proinflammatory status and reduced thermogenic function (Chapter 2). The DHA-enriched diet increased UCP1 levels and n-3 PUFA derived SPMs in iBAT, without recovering its impaired response to cold. Concerning the effects of long-term exercise in obese aged mice (Chapter 3), the scWAT showed an increase in fatty acid oxidation and a reduction in inflammatory genes, lower macrophage infiltration, and an increment in thermogenic and beige adipocytes genes. However, the iBAT was less responsive to exercise, revealing only a moderate stimulation of thermogenic genes/proteins. Importantly, the effects on scWAT and iBAT could contribute to the observed systemic effects exerted by DHA, which reduced total and LDL-cholesterol, and of exercise, which improved insulin resistance and glucose tolerance. Finally, the clinical trial in postmenopausal women with overweight/obesity (Chapters 4, 5), revealed that DHA supplementation induced lower diastolic blood pressure, inflammatory platelet-to-lymphocyte ratio, and circulating triglycerides. On the other hand, RT induced local fat mass losses and muscle mass gains, maintained whole-body bone mineral content and improved glucose tolerance and scWAT ADIPONECTIN expression. Both interventions reduced circulating C-reactive protein and scWAT mRNA levels of adipocytokines (LEPTIN, CHEMERIN, IL6) and M1 macrophages markers (CD11c). The combination of both treatments did not have any relevant synergistic effect. Overall, this research provides evidence that DHA supplementation and exercise training induce a beneficial remodeling of adipose tissue that could contribute to prevent the systemic inflammation and comorbidities of obesity and aging

Changes Induced by Aging and Long-Term Exercise and/or DHA Supplementation in Muscle of Obese Female Mice

Obesity and aging promote chronic low-grade systemic inflammation. The aim of the study was to analyze the effects of long-term physical exercise and/or omega-3 fatty acid Docosahexaenoic acid (DHA) supplementation on genes or proteins related to muscle metabolism, inflammation, muscle damage/regeneration and myokine expression in aged and obese mice. Two-month-old C57BL/6J female mice received a control or a high-fat diet for 4 months. Then, the diet-induced obese (DIO) mice were distributed into four groups: DIO, DIO + DHA, DIO + EX (treadmill training) and DIO + DHA + EX up to 18 months. Mice fed a control diet were sacrificed at 2, 6 and 18 months. Aging increased the mRNA expression of Tnf-α and decreased the expression of genes related to glucose uptake (Glut1, Glut4), muscle atrophy (Murf1, Atrogin-1, Cas-9) and myokines (Metrnl, Il-6). In aged DIO mice, exercise restored several of these changes. It increased the expression of genes related to glucose uptake (Glut1, Glut4), fatty acid oxidation (Cpt1b, Acox), myokine expression (Fndc5, Il-6) and protein turnover, decreased Tnf-α expression and increased p-AKT/AKT ratio. No additional effects were observed when combining exercise and DHA. These data suggest the effectiveness of long-term training to prevent the deleterious effects of aging and obesity on muscle dysfunction

Differential Responses to Sigma-1 or Sigma-2 Receptor Ablation in Adiposity, Fat Oxidation, and Sexual Dimorphism

Obesity is increasing at epidemic rates across the US and worldwide, as are its co-morbidities, including type-2 diabetes and cardiovascular disease. Thus, targeted interventions to reduce the prevalence of obesity are of the utmost importance. The sigma-1 receptor (S1R) and sigma-2 receptor (S2R; encoded by Tmem97) belong to the same class of drug-binding sites, yet they are genetically distinct. There are multiple ongoing clinical trials focused on sigma receptors, targeting diseases ranging from Alzheimer’s disease through chronic pain to COVID-19. However, little is known regarding their gene-specific role in obesity. In this study, we measured body composition, used a comprehensive laboratory-animal monitoring system, and determined the glucose and insulin tolerance in mice fed a high-fat diet. Compared to Sigmar1+/+ mice of the same sex, the male and female Sigmar1−/− mice had lower fat mass (17% and 12% lower, respectively), and elevated lean mass (16% and 10% higher, respectively), but S1R ablation had no effect on their metabolism. The male Tmem97−/− mice exhibited 7% lower fat mass, 8% higher lean mass, increased volumes of O2 and CO2, a decreased respiratory exchange ratio indicating elevated fatty-acid oxidation, and improved insulin tolerance, compared to the male Tmem97+/+ mice. There were no changes in any of these parameters in the female Tmem97−/− mice. Together, these data indicate that the S1R ablation in male and female mice or the S2R ablation in male mice protects against diet-induced adiposity, and that S2R ablation, but not S1R deletion, improves insulin tolerance and enhances fatty-acid oxidation in male mice. Further mechanistic investigations may lead to translational strategies to target differential S1R/S2R regulations and sexual dimorphism for precision treatments of obesity

Distinct Effects of High-Fat and High-Phosphate Diet on Glucose Metabolism and the Response to Voluntary Exercise in Male Mice

The prevalence of metabolic diseases is rapidly increasing and a principal contributor to this is diet, including increased consumption of energy-rich foods and foods with added phosphates. Exercise is an effective therapeutic approach to combat metabolic disease. While exercise is effective to combat the detrimental effects of a high-fat diet on metabolic health, the effects of exercise on a high-phosphate diet have not been thoroughly investigated. Here, we investigated the effects of a high-fat or high-phosphate diet in the presence or absence of voluntary exercise on metabolic function in male mice. To do this, mice were fed a low-fat, normal-phosphate diet (LFPD), a high-phosphate diet (HPD) or a high-fat diet (HFD) for 6 weeks and then subdivided into either sedentary or exercised (housed with running wheels) for an additional 8 weeks. An HFD severely impaired metabolic function in mice, increasing total fat mass and worsening whole-body glucose tolerance, while HPD did not induce any notable effects on glucose metabolism. Exercise reverted most of the detrimental metabolic adaptations induced by HFD, decreasing total fat mass and restoring whole-body glucose tolerance and insulin sensitivity. Interestingly, voluntary exercise had a similar effect on LFPD and HPD mice. These data suggest that a high-phosphate diet does not significantly impair glucose metabolism in sedentary or voluntary exercised conditions

Effect of aging and obesity on GLUT12 expression in small intestine, adipose tissue, muscle, and kidney and its regulation by docosahexaenoic acid and exercise in mice

Obesity is characterized by excessive fat accumulation and inflammation. Aging has also been characterized as an inflammatory condition, frequently accompanied by accumulation of visceral fat. Beneficial effects of exercise and n-3 long-chain polyunsaturated fatty acids in metabolic disorders have been described. Glucose transporter 12 (GLUT12) is one of the less investigated members of the GLUT family. Glucose, insulin, and tumor necrosis factor alpha (TNF-α) induce GLUT12 translocation to the membrane in muscle, adipose tissue, and intestine. We aimed to investigate GLUT12 expression in obesity and aging, and under diet supplementation with docosahexaenoic acid (DHA) alone or in combination with physical exercise in mice. Aging increased GLUT12 expression in intestine, kidney, and adipose tissue, whereas obesity reduced it. No changes on the transporter occurred in skeletal muscle. In obese 18-month-old mice, DHA further decreased GLUT12 in the 4 organs. Aerobic exercise alone did not modify GLUT12, but the changes triggered by exercise were able to prevent the DHA-diminishing effect, and almost restored GLUT12 basal levels. In conclusion, the downregulation of metabolism in aging would be a stimulus to upregulate GLUT12 expression. Contrary, obesity, an excessive energy condition, would induce GLUT12 downregulation. The combination of exercise and DHA would contribute to restore basal function of GLUT12. Novelty In small intestine, kidney and adipose tissue aging increases GLUT12 protein expression whereas obesity reduces it. Dietary DHA decreases GLUT12 in small intestine, kidney, adipose tissue and skeletal muscle. Exercise alone does not modify GLUT12 expression, nevertheless exercise prevents the DHA-diminishing effect on GLUT12.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author