Adipose tissue, but not skeletal muscle, sirtuin 1 expression is decreased in obesity and related to insulin sensitivity

Metabolomics in cardiometabolic diseases: Key biomarkers and therapeutic implications for insulin resistance and diabetes

Cardiometabolic diseases-including Type 2 diabetes and obesity-remain leading causes of global mortality. Recent advancements in metabolomics have facilitated the identification of metabolites that are integral to the development of insulin resistance, a characteristic feature of cardiometabolic disease. Key metabolites, such as branched-chain amino acids (BCAAs), ceramides, glycine, and glutamine, have emerged as valuable biomarkers for early diagnosis, risk stratification, and potential therapeutic targets. Elevated BCAAs and ceramides are strongly associated with insulin resistance and Type 2 diabetes, whereas glycine exhibits an inverse relationship with insulin resistance, making it a promising therapeutic target. Metabolites involved in energy stress, including ketone bodies, lactate, and nicotinamide adenine dinucleotide (NAD⁺), regulate insulin sensitivity and metabolic health, with ketogenic diets and NAD⁺ precursor supplementation showing potential benefits. Additionally, the novel biomarker N-lactoyl-phenylalanine further underscores the complexity of metabolic regulation and its therapeutic potential. This review underscores the potential of metabolite-based diagnostics and precision medicine, which could enhance efforts in the prevention, diagnosis, and treatment of cardiometabolic diseases, ultimately improving patient outcomes and quality of life.

Piceatannol Upregulates SIRT1 Expression in Skeletal Muscle Cells and in Human Whole Blood: In Vitro Assay and a Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Comparison Trial

Piceatannol (PIC), a polyphenol abundant in passion fruit seeds, is reported to promote fat metabolism. This study investigated whether PIC affects sirtuin 1 (SIRT1) expression and metabolic factors in C2C12 skeletal muscle cells. C2C12 myotubes were stimulated with PIC, and alterations in gene expression, protein levels, mitochondrial DNA content, and fatty acid levels were assessed using real-time PCR, Western blotting, and Nile red staining. Furthermore, we examined changes in SIRT1 expression following the consumption of a test food containing 100 mg PIC for 2 weeks among adults with varying age and body mass index ranges. Both PIC and passion fruit seed extract induced SIRT1 expression in C2C12 myotubes to a greater extent than resveratrol. PIC also increased the expression of genes associated with mitochondrial biogenesis and fatty acid utilization, increased mitochondrial DNA content, and suppressed oleic acid-induced fat accumulation. Moreover, participants who consumed PIC exhibited significantly higher SIRT1 mRNA expression in whole blood compared to those in the placebo group. These findings suggest that PIC induces SIRT1 expression both in vitro and in the human body, which may promote mitochondrial biosynthesis and fat metabolism.

Subcutaneous adipose tissue circadian gene expression: Relationship with insulin sensitivity, obesity, and the effect of weight-reducing dietary intervention

OBJECTIVE

The circadian rhythms are controlled by the central clock in the hypothalamic suprachiasmatic nuclei and by the peripheral clocks in tissues, including adipose tissue. The adipose tissue circadian clock may be associated with the regulation of insulin action; however, human data are limited. The aim of this study was to analyze the expression of subcutaneous adipose tissue circadian genes as they relate to obesity and insulin sensitivity before and after diet-induced weight loss.

METHODS

The study group comprised 38 individuals who were overweight or obese. The individuals completed a 12-wk dietary intervention program. Hyperinsulinemic-euglycemic clamp and subcutaneous adipose tissue biopsy were performed before and after the program. Sixteen normal weight individuals were examined at baseline and served as a control group.

RESULTS

At baseline, individuals who were overweight/obese had lower adipose tissue expression of NR1D1, NR1D2, DBP, PER1, and PER2 than normal weight individuals. The expression of ARNTL, CLOCK, and CRY did not differ between the groups. A weight-reducing dietary intervention resulted in an increase in the expression of adipose tissue NR1D2 and DBP, which was positively related to insulin sensitivity both before (in the entire study group and in the subgroup of overweight/obese individuals) and after the dietary intervention.

CONCLUSIONS

Adipose tissue circadian gene expression is decreased in obesity and this decrease may be partially reversed by dietary intervention. Among circadian genes, NR1D2 and DBP seem to be specifically associated with insulin action.

Assessment of global histone acetylation in pediatric and adolescent obesity: Correlations with SIRT1 expression and metabolic-inflammatory profiles

BACKGROUND

Epigenetic modifications, particularly histone acetylation-deacetylation and its related enzymes, such as sirtuin 1 (SIRT1) deacetylase, may have substantial roles in the pathogenesis of obesity and its associated health issues. This study aimed to evaluate global histone acetylation status and SIRT1 gene expression in children and adolescents with obesity and their association with metabolic and anthropometric parameters.

METHODS

This study included 60 children and adolescents, 30 with obesity and 30 normal-weight. The evaluation consisted of the analysis of global histone acetylation levels and the expression of the SIRT1 gene in peripheral blood mononuclear cells, by specific antibody and real-time PCR, respectively. Additionally, insulin, fasting plasma glucose, lipid profile and tumor necrosis factor α (TNF-α) levels were measured. Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). Metabolic syndrome was determined based on the diagnostic criteria established by IDF.

RESULTS

Individuals with obesity, particularly those with insulin resistance, had significantly higher histone acetylation levels compared to control group. Histone acetylation was positively correlated with obesity indices, TNF-α, insulin, and HOMA-IR. Additionally, a significant decrease in SIRT1 gene expression was found among obese individuals, which was negatively correlated with the histone acetylation level. Furthermore, SIRT1 expression levels showed a negative correlation with various anthropometric and metabolic parameters.

CONCLUSION

Histone acetylation was enhanced in children and adolescents with obesity, potentially resulting from down-regulation of SIRT1, and could play a role in the obesity-associated metabolic abnormalities and insulin resistance. Targeting global histone acetylation modulation might be considered as an epigenetic approach for early obesity management.

Understanding the Impact of Obesity on Ageing in the Radiance of DNA Metabolism

Ageing is a multi-factorial phenomenon which is considered as a major risk factor for the development of neurodegeneration, osteoporosis, cardiovascular disease, dementia, cancer, and other chronic diseases. Phenotypically, ageing is related with a combination of molecular, cellular, and physiological levels like genomic and epi-genomic alterations, loss of proteostasis, deregulation of cellular and subcellular function and mitochondrial dysfunction. Though, no single molecular mechanism accounts for the functional decline of different organ systems in older humans but accumulation of DNA damage or mutations is a dominant theory which contributes largely to the development of ageing and age-related diseases. However, mechanistic, and hierarchical order of these features of ageing has not been clarified yet. Scientific community now focus on the effect of obesity on accelerated ageing process. Obesity is a complex chronic disease that affects multiple organs and tissues. It can not only lead to various health conditions such as diabetes, cancer, and cardiovascular disease but also can decrease life expectancy which shows similar phenotype of ageing. Higher loads of DNA damage were also observed in the genome of obese people. Thus, inability of DNA damage repair may contribute to both ageing and obesity apart from cancer predisposition. The present review emphasizes on the involvement of molecular phenomenon of DNA metabolism in development of obesity and how it accelerates ageing in mammals.

HIGHER SIRT1 IS ASSOCIATED WITH A BETTER BODY COMPOSITION IN MASTER SPRINTERS AND UNTRAINED PEERS

Sirt1 is an enzyme involved in several anti-aging pathways. Associations between Sirt1, age, and body fat (BF) were assessed in master sprinters (MS; n = 35; 50.25 ±5.93 yr.), untrained young non-athletes (UY; n = 32; 23.78 ±3.98 yr.), and untrained middle-aged (UMA; n = 24; 47.29 ±8.04 yr.). BF was assessed using a skinfold protocol, and Sirt1 was measured in plasma by using commercial kits. Sirt1 of MS (17.18 ±4.77 ng/mL) was higher than UMA (6.36 ±2.29 ng/mL; p<0.0001) and did not differ from UY (20.26 ±6.20 ng/mL). Relative BF of MS was lower than UMA (12.71 ±4.07% vs. 22.13 ±4.18%; p<0.0001). Sirt1 was negatively correlated with chronological age (r =-0.735; p<0.0001) when combining UY and UMA in the analysis. However, when Sirt1 of MS and UY were analyzed together, no significant relationship between Sirt1 and chronological age was observed (r= -0.243; p=0.083). Sirt1 correlated inversely with BF (r= -0.743; p<0.0001) for UY and UMA. Stepwise multiple regression revealed that being either a young or master athlete, as well as body adiposity, are possible predictors of Sirt1 levels. MS and UY were associated with higher levels of Sirt1, while UMA and increased BF were associated with lower levels of this enzyme. The relationships among Sirt1, BF, and chronological age of young and middle-aged non-athletes were not statistically significant when the middle-aged participants were MS. These findings suggest possible links between Sirt1 and body composition, which may play roles in the rate of biological aging.Highlights Lower levels of Sirt1 are associated with higher body fat.Master Athlete lifestyle seems to promote higher Sirt1 Levels.

The Mystery of Exosomes in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is one of the common pregnancy complications, which increases the risk of short-term and long-term adverse consequences in both the mother and offspring. However, the pathophysiological mechanism of GDM is still poorly understood. Inflammation, insulin resistance and oxidative stress are considered critical factors in the occurrence and development of GDM. Although the lifestyle intervention and insulin are the primary treatment, adverse pregnancy outcomes still cannot be ignored. Exosomes have a specific function of carrying biological information, which can transmit information to target cells and play an essential role in intercellular communication. Their possible roles in normal pregnancy and GDM have been widely concerned. The possibility of exosomal cargos as biomarkers of GDM is proposed. This paper reviews the literature in recent years and discusses the role of exosomes in GDM and their possible mechanisms to provide some reference for the prediction, prevention, and treatment of GDM and improve the outcome of pregnancy.

Sulfated Polysaccharides from Enteromorpha prolifera Attenuate Lipid Metabolism Disorders in Mice with High-fat Diet-induced Obesity via an AMPK-dependent Pathway

BACKGROUND

Obesity-related metabolic diseases have recently evoked worldwide attention. Studies have demonstrated that Enteromorpha polysaccharide (EP) exerts lipid-lowering effects, but the underlying mechanism remains unclear.

OBJECTIVE

To investigate whether EP regulates lipid metabolism disorders in mice with high-fat diet (HFD)-induced obesity via an AMP-activated protein kinase (AMPK)-dependent pathway.

METHODS

Six-week-old male C57BL/6J mice (18 ± 2 g) were fed a normal diet (ND; 10% energy from fats) or a HFD (60% energy from fats) for 6 weeks to induce obesity and treated intragastrically with EP (200 mg/kg body weight) or distilled water (10 mL/kg body weight) for 8 weeks. Biochemical indicators, AMPK-dependent pathways and lipid metabolism-related genes were evaluated to assess the effects of EP on HFD-induced lipid metabolism disorders. The essential role of AMPK in the EP-mediated regulation of lipid metabolism was confirmed using HFD-fed male Ampka2-knockout mice (aged 6 weeks, 17 ± 2 g) treated or not treated with the above-mentioned dose of EP. The data were analyzed by t tests and two-factor and one-way ANOVAs.

RESULTS

Compared to the ND, the HFD resulted in the greater body weight (24.3%), perirenal fat index (2.2-fold), and serum TC (24.66%) and LDL cholesterol (1.25-fold) concentrations (P < 0.05) and dysregulated the AMPK-dependent pathway and the expression of most lipid metabolism-related genes (P < 0.05). Compared to the HFD, EP treatment resulted in the lower perirenal fat index (31.22%) and the LDL-C concentration (23.98%) and partly reversed the dysregulation of the AMPK-dependent pathway and the altered expression of lipid metabolism-related genes (P < 0.05). Ampka2 knockout abolished the above-mentioned effects of EP in obese mice and the EP-mediated effects on the expression of lipid metabolism-related genes (P > 0.05).

CONCLUSIONS

These findings suggest that EP can ameliorate lipid metabolism disorders in mice with HFD-induced obesity via an AMPK-dependent pathway.

Butyl Benzyl Phthalate Promotes Adipogenesis in 3T3-L1 Cells via the miRNA-34a-5p Signaling Pathway in the Absence of Exogenous Adipogenic Stimuli

Phthalates, a plasticizer group, are used extensively in many of the products we use every day. Public health concerns are growing as recent studies have implicated butyl benzyl phthalate (BBP) as an obesogen. However, BBP-induced epigenetic regulation during adipogenesis is still unknown. We investigated if BBP altered miR-34a-5p, a key miRNA involved in obesity, and regulated its downstream pathway. Differentiating 3T3-L1 cells were exposed to various doses of BBP without exogenous adipogenic stimuli, tested for adipogenesis markers (PPARγ and aP2), and stained for lipid accumulation with Oil Red O staining. We then measured the expression of miR-34a-5p and its target genes, Nampt and Sirt1, along with another significant epigenetic modulator, Sirt3. Furthermore, using antagomiR, we examined whether miR-34a-5p knockdown decreased adipogenesis. BBP exposure resulted in augmented expression levels of miR-34a-5p with an associated increase in adipogenesis. BBP significantly decreased the Nampt, Sirt1, and Sirt3 gene expression levels. However, a decrease in the protein expression was observed only for Nampt, indicating that miR-34a-5p under BBP exposure may regulate Sirt1/Sirt3 only at the transcriptional level. Interestingly, in the presence of BBP, knockdown of miR-34a-5p decreased adipogenesis in the differentiating 3T3-L1 cells. Furthermore, miR-34a-5p knockdown increased the Nampt protein expression levels as well as NAD⁺ levels, indicating that miR-34a-5p regulates Nampt during BBP exposure. Additionally, the NAD⁺-dependent sirtuin activity decreased in BBP-treated cells and increased in miR-34a-5p knockdown cells with BBP treatment. BBP exposure demonstrated the involvement of epigenetic regulation by altering the expression patterns of miR-34a-5p and its target Nampt, which may perturb the energy homeostasis of the differentiating adipocytes by altering NAD⁺ levels and sirtuin activity, resulting in increased adipogenesis.

Randomized study of the effects of vitamin D and/or magnesium supplementation on mood, serum levels of BDNF, inflammation, and SIRT1 in obese women with mild to moderate depressive symptoms

OBJECTIVES

This study aimed to evaluate the effects of vitamin D and/or magnesium supplementation on mood, serum levels of BDNF, inflammation, and SIRT1 in obese women with mild to moderate depressive symptoms.

METHODS

In this trial, the 108 obese women with mild to moderate depressive symptoms were randomly allocated into 4 groups: (1) co- supplementation group (n = 27): receiving a 50000 IU vitamin D soft gel weekly + a 250- mg magnesium tablet daily; (2) vitamin D group (n = 27): receiving a 50000 IU vitamin D soft gel weekly + a magnesium placebo daily; (3) magnesium group (n = 27): receiving a vitamin D placebo weekly + a 250- mg magnesium tablet daily; (4) control group (n = 27): receiving a vitamin D placebo weekly + a magnesium placebo daily, for 8 weeks. Before and after the intervention, anthropometric indices, depressive symptoms, serum levels of BDNF, 25(OH)-D, inflammation, and SIRT1, were measured.

RESULTS

At the end of the study, ANCOVA demonstrated significant differences between the 4 groups in 25(OH)-D, magnesium, TNF-α, IL-6, and BDNF levels. But, we found no significant differences in terms of hs-CRP and SIRT1 levels. A significant reduction in depression score was observed in 3 intervention groups and also in control group. No significant differences in BDI-II score were shown among the 4 groups at the end of the intervention.

CONCLUSION

Vitamin D plus magnesium supplementation in obese women with mild to moderate depressive symptoms has beneficial influences on mood, serum levels of BDNF, inflammation, and SIRT1.

Effect of intermittent and continuous caloric restriction on Sirtuin1 concentration depends on sex and body mass index

BACKGROUND & AIMS

The favorable effect of caloric restriction (CR) on health span is well known and partly mediated by the sirtuin system. Sirtuin1, a regulator of energy homeostasis in response to nutrient availability, is activated by CR. We therefore investigated effects of two different CR regimens on Sirtuin1 concentrations.

METHODS & RESULTS

The study included 112 abdominally obese subjects, randomized to intermittent or continuous CR for 1 year. Blood samples and anthropometric measures were collected at baseline and after 12 months. Sirtuin1 concentrations were measured by ELISA. Sirtuin1 correlated significantly to BMI at baseline (r = .232, p = 0.019). Mean reduction in body-weight was 8.0 and 9.0 kg after intermittent and continuous CR, respectively. After 1 year, no significant between-group differences in Sirtuin1 levels were observed according to regimen (p = 0.98) and sex (p = 0.41). An increase in median Sirtuin1 concentrations (pg/mL) [25, 75 percentiles] from baseline was observed after intermittent CR in the total population (884 [624, 1285] vs.762 [530, 1135]; p = 0.041), most marked in men (820 [623, 1250] vs. 633 [524, 926]; p = 0.016). Improvement in BMI after 1 year correlated to Sirtuin1 changes, but varied according to sex. In women, Spearman's rho = .298, p = 0.034, with stronger correlation in the intermittent CR group (r = .424, p = 0.049). In men, there was an inverse relation to Sirtuin1 changes, only in the intermittent CR group (r = -.396, p = 0.045).

CONCLUSIONS

Effects on Sirtuin1 concentrations after 1 year of CR are sex and BMI-related. Intermittent CR regimen affected Sirtuin1 to a stronger extent than continuous CR, suggesting individualized dietary intervention.

An update in toxicology of ageing

The field of ageing research has been rapidly advancing in recent decades and it had provided insight into the complexity of ageing phenomenon. However, as the organism-environment interaction appears to significantly affect the organismal pace of ageing, the systematic approach for gerontogenic risk assessment of environmental factors has yet to be established. This puts demand on development of effective biomarker of ageing, as a relevant tool to quantify effects of gerontogenic exposures, contingent on multidisciplinary research approach. Here we review the current knowledge regarding the main endogenous gerontogenic pathways involved in acceleration of ageing through environmental exposures. These include inflammatory and oxidative stress-triggered processes, dysregulation of maintenance of cellular anabolism and catabolism and loss of protein homeostasis. The most effective biomarkers showing specificity and relevancy to ageing phenotypes are summarized, as well. The crucial part of this review was dedicated to the comprehensive overview of environmental gerontogens including various types of radiation, certain types of pesticides, heavy metals, drugs and addictive substances, unhealthy dietary patterns, and sedentary life as well as psychosocial stress. The reported effects in vitro and in vivo of both recognized and potential gerontogens are described with respect to the up-to-date knowledge in geroscience. Finally, hormetic and ageing decelerating effects of environmental factors are briefly discussed, as well.

Sirtuins-Mediated System-Level Regulation of Mammalian Tissues at the Interface between Metabolism and Cell Cycle: A Systematic Review

Sirtuins are a family of highly conserved NAD+-dependent proteins and this dependency links Sirtuins directly to metabolism. Sirtuins' activity has been shown to extend the lifespan of several organisms and mainly through the post-translational modification of their many target proteins, with deacetylation being the most common modification. The seven mammalian Sirtuins, SIRT1 through SIRT7, have been implicated in regulating physiological responses to metabolism and stress by acting as nutrient sensors, linking environmental and nutrient signals to mammalian metabolic homeostasis. Furthermore, mammalian Sirtuins have been implicated in playing major roles in mammalian pathophysiological conditions such as inflammation, obesity and cancer. Mammalian Sirtuins are expressed heterogeneously among different organs and tissues, and the same holds true for their substrates. Thus, the function of mammalian Sirtuins together with their substrates is expected to vary among tissues. Any therapy depending on Sirtuins could therefore have different local as well as systemic effects. Here, an introduction to processes relevant for the actions of Sirtuins, such as metabolism and cell cycle, will be followed by reasoning on the system-level function of Sirtuins and their substrates in different mammalian tissues. Their involvement in the healthy metabolism and metabolic disorders will be reviewed and critically discussed.

Chrysanthemum morifolium Flower Extract Inhibits Adipogenesis of 3T3-L1 Cells via AMPK/SIRT1 Pathway Activation

Chrysanthemum (Chrysanthemum morifolium Ramat) flowers (CF) are widely consumed as herbal tea in many countries, including China. The aim of the present study was to examine the anti-adipogenic effect of hot water extraction of CF (HCF) on 3T3-L1 cells and their underlying cellular mechanisms. HCF treatment inhibited lipid accumulation under conditions that did not show the toxicity of 3T3-L1 adipocytes. The activity of glycerol-3-phosphate dehydrogenase (GPDH), which plays an important role in glycerol lipid metabolism, was also reduced by HCF. Adipogenesis/lipogenesis-related mRNA expression levels of peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding protein-α (CEBP-α), sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid-binding protein 4 (FABP4), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FAS) were suppressed by HCF in a dose-dependent manner. Moreover, HCF increased activities of AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1), involved in lipid metabolism. These findings suggest that HCF inhibits adipocyte lipid accumulation through suppression of adipogenesis/lipogenesis-related gene expression and activation of the AMPK/SIRT1 pathway. Therefore, it suggests that HCF may be used as a potentially beneficial plant material for preventing obesity.

Adipose depot-specific upregulation of Ucp1 or mitochondrial oxidative complex proteins are early consequences of genetic insulin reduction in mice

Hyperinsulinemia plays a causal role in adipose tissue expansion. Mice with reduced insulin have increased energy expenditure, but the mechanisms remained unclear. Here we investigated the effects of genetically reducing insulin production on uncoupling and oxidative mitochondrial proteins in liver, skeletal muscle, white adipose tissue (WAT), and brown adipose tissue (BAT). Male Ins1^+/+ or Ins1^+/- littermates were fed either a low-fat diet (LFD) or a high-fat diet (HFD) for 4 wk, starting at 8 wk of age. Replicating our previous observations, HFD increased fasting hyperinsulinemia, and Ins1^+/- mice had significantly lower circulating insulin compared with Ins1^+/+ littermates. Fasting glucose and body weight were not different between genotypes. We did not observe robust significant differences in liver or skeletal muscle. In mesenteric WAT, Ins1^+/- mice had reduced Ndufb8 and Sdhb, while Ucp1 was increased in the context of HFD. HFD alone had a dramatic inhibitory effect on Pparg abundance. In inguinal WAT, Ins1^+/- mice exhibited significant increases in oxidative complex proteins, independent of diet, without affecting Ucp1, Pparg, or Prdm16:Pparg association. In BAT, lowered insulin increased Sdhb protein levels that had been reduced by HFD. Ucp1 protein, Prdm16:Pparg association, and Sirt3 abundance were all increased in the absence of diet-induced hyperinsulinemia. Our data show that reducing insulin upregulates oxidative proteins in inguinal WAT without affecting Ucp1, whereas in mesenteric WAT and BAT, reducing insulin upregulates Ucp1 in the context of HFD. Preventing hyperinsulinemia has early depot-specific effects on adipose tissue metabolism and helps explain the increased energy expenditure previously reported in Ins1^+/- mice.

Environment and Gene Association With Obesity and Their Impact on Neurodegenerative and Neurodevelopmental Diseases

Obesity is a multifactorial disease in which environmental conditions and several genes play an important role in the development of this disease. Obesity is associated with neurodegenerative diseases (Alzheimer, Parkinson, and Huntington diseases) and with neurodevelopmental diseases (autism disorder, schizophrenia, and fragile X syndrome). Some of the environmental conditions that lead to obesity are physical activity, alcohol consumption, socioeconomic status, parent feeding behavior, and diet. Interestingly, some of these environmental conditions are shared with neurodegenerative and neurodevelopmental diseases. Obesity impairs neurodevelopment abilities as memory and fine-motor skills. Moreover, maternal obesity affects the cognitive function and mental health of the offspring. The common biological mechanisms involved in obesity and neurodegenerative/neurodevelopmental diseases are insulin resistance, pro-inflammatory cytokines, and oxidative damage, among others, leading to impaired brain development or cell death. Obesogenic environmental conditions are not the only factors that influence neurodegenerative and neurodevelopmental diseases. In fact, several genes implicated in the leptin-melanocortin pathway (LEP, LEPR, POMC, BDNF, MC4R, PCSK1, SIM1, BDNF, TrkB, etc.) are associated with obesity and neurodegenerative and neurodevelopmental diseases. Moreover, in the last decades, the discovery of new genes associated with obesity (FTO, NRXN3, NPC1, NEGR1, MTCH2, GNPDA2, among others) and with neurodegenerative or neurodevelopmental diseases (APOE, CD38, SIRT1, TNFα, PAI-1, TREM2, SYT4, FMR1, TET3, among others) had opened new pathways to comprehend the common mechanisms involved in these diseases. In conclusion, the obesogenic environmental conditions, the genes, and the interaction gene-environment would lead to a better understanding of the etiology of these diseases.

Role of Histone Deacetylases in Skeletal Muscle Physiology and Systemic Energy Homeostasis: Implications for Metabolic Diseases and Therapy

Skeletal muscle is the largest metabolic organ in the human body and is able to rapidly adapt to drastic changes during exercise. Histone acetyltransferases (HATs) and histone deacetylases (HDACs), which target histone and non-histone proteins, are two major enzyme families that control the biological process of histone acetylation and deacetylation. Balance between these two enzymes serves as an essential element for gene expression and metabolic and physiological function. Genetic KO/TG murine models reveal that HDACs possess pivotal roles in maintaining skeletal muscles' metabolic homeostasis, regulating skeletal muscles motor adaptation and exercise capacity. HDACs may be involved in mitochondrial remodeling, insulin sensitivity regulation, turn on/off of metabolic fuel switching and orchestrating physiological homeostasis of skeletal muscles from the process of myogenesis. Moreover, many myogenic factors and metabolic factors are modulated by HDACs. HDACs are considered as therapeutic targets in clinical research for treatment of cancer, inflammation, and neurological and metabolic-related diseases. This review will focus on physiological function of HDACs in skeletal muscles and provide new ideas for the treatment of metabolic diseases.

Type B insulin resistance syndrome associated with connective tissue disease and psoriasis

SUMMARY

Type B insulin resistance syndrome (TBIR) is characterised by the rapid onset of severe insulin resistance due to circulating anti-insulin receptor antibodies (AIRAs). Widespread acanthosis nigricans is normally seen, and co-occurrence with other autoimmune diseases is common. We report a 27-year-old Caucasian man with psoriasis and connective tissue disease who presented with unexplained rapid weight loss, severe acanthosis nigricans, and hyperglycaemia punctuated by fasting hypoglycaemia. Severe insulin resistance was confirmed by hyperinsulinaemic euglycaemic clamping, and immunoprecipitation assay demonstrated AIRAs, confirming TBIR. Treatment with corticosteroids, metformin and hydroxychloroquine allowed withdrawal of insulin therapy, with stabilisation of glycaemia and diminished signs of insulin resistance; however, morning fasting hypoglycaemic episodes persisted. Over three years of follow-up, metabolic control remained satisfactory on a regimen of metformin, hydroxychloroquine and methotrexate; however, psoriatic arthritis developed. This case illustrates TBIR as a rare but severe form of acquired insulin resistance and describes an effective multidisciplinary approach to treatment.

LEARNING POINTS

We describe an unusual case of type B insulin resistance syndrome (TBIR) in association with mixed connective tissue disease and psoriasis. Clinical evidence of severe insulin resistance was corroborated by euglycaemic hyperinsulinaemic clamp, and anti-insulin receptor autoantibodies were confirmed by immunoprecipitation assay. Treatment with metformin, hydroxychloroquine and methotrexate ameliorated extreme insulin resistance.

Effects of vitamin D and/or magnesium supplementation on mood, serum levels of BDNF, inflammatory biomarkers, and SIRT1 in obese women: a study protocol for a double-blind, randomized, placebo-controlled trial

Background

Emerging evidence has shown that vitamin D and magnesium have anti-inflammatory and anti-depressant effects. Dietary intake of magnesium is associated with reduced body mass index, waist circumference, body fat percentage, as well as inflammatory biomarkers and depressive symptoms. Vitamin D deficiency has been linked to inflammation, obesity, and depressive symptoms. This study will test the effects of vitamin D and magnesium co-supplementation on mood, serum level of brain-derived neurotrophic factor (BDNF), inflammation, and sirtuin 1 (SIRT1) in obese women.

Methods

We will conduct an 8-week, double-blind, randomized, placebo-controlled clinical trial, in a factorial design, to evaluate the individual effects of vitamin D and magnesium, and co-supplementation of them, on mood, serum level of BDNF, inflammation, and SIRT1 in 108 obese women.

Discussion

We hypothesize that vitamin D and magnesium co-supplementation may provide a new adjuvant therapy through modulation of BDNF, inflammation, and SIRT1 in obese women.

Trial registration

Iranian Registry of Clinical Trials, IRCT20090822002365N23. Registered on 16 August 2019.

Shorter Leukocyte Telomere Lengths in Healthy Relatives of Patients with Coronary Heart Disease

Telomere length (TL), sirtuin (SIRT) 1, growth differentiation factor (GDF) 11, as well as inflammaging have been related to age-related diseases. In healthy subjects, we aimed to investigate whether leukocyte TL (LTL) associated with family history of coronary heart disease (CHD), age, sex, and lifestyle, and further potential covariations between LTL, GDF11, SIRT1 and selected proinflammatory markers. In 118 healthy subjects (18-81 years, 58% females), whole blood was collected for DNA and RNA isolation and polymerase chain reaction relative quantification of LTLs and gene-expression of SIRT1, GDF11, interleukin (IL)-18, and interferon (IFN)ƴ, respectively, and serum SIRT1 and IL-18 analyses. Shorter LTLs were associated with a seven-fold higher frequency of hereditary CHD in subjects with LTLs in quartile (Q)1 compared with Q2-4 (odds ratio = 7.5, 95% confidence interval: 2.5-21.6, p < 0.001, adjusted). We also observed that LTLs in Q4 compared with Q1-3 associated with higher leukocyte expression of SIRT1 and GDF11 (p = 0.052 and p = 0.058), lower IFNƴ expression (p = 0.009), and lower circulating IL-18 levels (p = 0.027). SIRT1 and GDF11 expression were strongly intercorrelated (Spearman's rho = 0.85, p < 0.001). Overall, smoking, snus, and alcohol consumption were not associated with LTLs. The observed shorter LTLs in association with elevated expression of SIRT1 and GDF11 and dampened inflammation in hereditary CHD subjects, suggest impending risk of disease. More research are warranted to shed light on early lifestyle interventions targeting these mechanisms, to promote healthier aging in individuals with hereditary burden. Graphical Abstract [Figure: see text].

Down-Regulation of SIRT1 Expression by mir-23b Contributes to Lipid Accumulation in HepG2 Cells

Non-alcoholic fatty liver disease is one of the main causes of chronic liver disease and therefore is currently considered a major public health problem. Sirtuin 1 (SIRT1) is an NAD-dependent deacetylase enzyme that contributes in the regulation of metabolic processes and protects against lipid accumulation in hepatocytes. Its expression is potentially regulated by microRNAs which attach to the 3' untranslated region (3'-UTR) of their target mRNA. HepG2 cells were incubated by glucose to induce lipid accumulation and were subsequently transfected with mir-23b mimic and inhibitor. Real-time PCR was used for measuring the expression of mir-23b and SIRT1 mRNA. Cell survival assay and intracellular triglyceride measurement were performed using colorimetric methods. Determination of SIRT1 protein level and activity were done by western blot and fluorometric analysis, respectively. The interaction of miR-23b with 3'-UTR of SIRT1 mRNA was confirmed by dual luciferase. miR-23b mimic inhibited gene and protein expression of SIRT1, while the inhibitor of miR-23b significantly elevated the expression levels of SIRT1 mRNA and protein. The results showed that the 3'-UTR of SIRT1 mRNA is a direct target for miR-23b. The intracellular triglyceride level was increased following the inhibition of SIRT1 in transfected HepG2 cell by miR-23b mimic. Cell viability was decreased in response to miR-23b upregulation compared to control cells. miR-23b reduces the expression and activity of SIRT1 and therefore may be a causative factor in the enhancement of lipid accumulation in HepG2 cells.

Monounsaturated Fatty Acids in a High-Fat Diet and Niacin Protect from White Fat Dysfunction in the Metabolic Syndrome

SCOPE

Obesity is a principal causative factor of metabolic syndrome. Niacin potently regulates lipid metabolism. Replacement of saturated fatty acids by MUFAs or inclusion of omega-3 long-chain PUFAs in the diet improves plasma lipid levels. However, the potential benefits of niacin in combination with MUFAs or omega-3 long-chain PUFAs against white adipose tissue (WAT) dysfunction in the high fat diet (HFD)-induced metabolic syndrome are unknown.

METHODS AND RESULTS

Male Lep^ob/ob LDLR^-/- mice are fed a chow diet or HFDs based on milk cream (21% kcal), olive oil (21% kcal), or olive oil (20% kcal) plus 1% kcal from eicosapentaenoic and docosahexaenoic acids, including immediate-release niacin (1% w/v) in drinking water, for 8 weeks. Mice are then phenotyped. Dietary MUFAs are identified as positive regulators of adipose NAD⁺ signaling pathways by triggering NAD⁺ biosynthesis via the salvage pathway. This coexists with overexpression of genes involved in recognition of NAD⁺ and fatty acids, a surrounding lipid environment dominated by exogenous oleic acid and an alternatively activated macrophage profile, which culminate in a healthy expansion of WAT and improvement of several hallmarks that typify the metabolic syndrome.

CONCLUSION

Niacin in combination with dietary MUFAs can favor WAT homeostasis in the development of HFD-induced obesity and metabolic syndrome.

Adipose Tissue Exosomal Proteomic Profile Reveals a Role on Placenta Glucose Metabolism in Gestational Diabetes Mellitus

CONTEXT

Molecules produced by adipose tissue (AT) function as an endocrine link between maternal AT and fetal growth by regulating placental function in normal women and women with gestational diabetes mellitus (GDM).

OBJECTIVE

We hypothesized that AT-derived exosomes (exo-AT) from women with GDM would carry a specific set of proteins that influences glucose metabolism in the placenta.

DESIGN

Exosomes were isolated from omental AT-conditioned media from normal glucose tolerant (NGT) pregnant women (n = 65) and pregnant women with GDM (n = 82). Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry was used to construct a small ion library from AT and exosomal proteins, followed by ingenuity pathway analysis to determine the canonical pathways and biofunctions. The effect of exosomes on human placental cells was determined using a Human Glucose Metabolism RT2 Profiler PCR array.

RESULTS

The number of exosomes (vesicles/μg of tissue/24 hours) was substantially (1.7-fold) greater in GDM than in NGT, and the number of exosomes correlated positively with the birthweight Z score. Ingenuity pathway analysis of the exosomal proteins revealed differential expression of the proteins targeting the sirtuin signaling pathway, oxidative phosphorylation, and mechanistic target of rapamycin signaling pathway in GDM compared with NGT. GDM exo-AT increased the expression of genes associated with glycolysis and gluconeogenesis in placental cells compared with the effect of NGT exo-AT.

CONCLUSIONS

Our findings are consistent with the possibility that AT exosomes play an important role in mediating the changes in placental function in GDM and might be responsible for some of the adverse consequences in this pregnancy complication, such as fetal overgrowth.

The effect of moderate weight loss, with or without (1, 3)(1, 6)-β-glucan addition, on subcutaneous adipose tissue inflammatory gene expression in young subjects with uncomplicated obesity

PURPOSE

Obesity is characterized by insulin resistance and low-grade systemic and adipose tissue (AT) inflammation. It remains unclear whether beneficial effects of weight loss are related to AT inflammation. We aimed to assess the effect of weight loss during low-calorie diet on insulin sensitivity, AT expression of genes associated with inflammation in young subjects with obesity. Furthermore, we estimated the effects of immunomodulatory (1, 3)(1, 6)-β-glucan (BG) on the above parameters.

METHODS

The study group comprised 52 subjects with obesity. Twelve-week dietary intervention was applied, with randomization to receive or not 500 mg BG daily. Euglycemic hyperinsulinemic clamp, subcutaneous AT biopsy were performed before and after the program. Twenty normal-weight subjects, examined at baseline, served as a control group.

RESULTS

At baseline, obese subjects had lower insulin sensitivity, lower AT ADIPOQ, JAK1, and JAK2 expression and higher AT expression of LEP, IL6ST, STAT3, MIF, CCL2, MMP9, and IL18. Forty obese subjects completed dietary intervention program, which resulted in 11.3% weight loss and 27% increase in insulin sensitivity (both p < 0.0001). AT IL6R, IL6ST, JAK1, and JAK2 expression increased, whereas MIF, CCL2, MMP9, and IL18 gene expression did not change in response to weight loss. BG addition had no effect on any of the parameters studied.

CONCLUSIONS

Our data indicate that reduction in AT inflammation is not required for an improvement in insulin action during weight loss in subjects with uncomplicated obesity. BG does not have effects during dietary intervention.

Detection of Sirtuin-1 protein expression in peripheral blood leukocytes in dogs

Sirtuin-1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylase with a large number of protein substrates. It has attracted a lot of attention in association with extending lifespan. The objective of this study was to enable the evaluation of SIRT1 expression in peripheral blood mononuclear cells (PBMCs) from dogs by flow cytometry. Three transcript variants were amplified from PBMCs by reverse transcription PCR and the nucleotide sequences were analyzed. On the basis of deduced amino acid sequence, a monoclonal antibody against human SIRT1, 1F3, was selected to detect canine SIRT1. Canine SIRT1 in peripheral blood mononuclear cells was successfully detected by western blotting using this antibody. Intracellular canine SIRT1 was also detected in permeabilized 293T cells transfected with a canine SIRT1 expression plasmid by flow cytometry using this antibody. SIRT1 was detected in all leukocyte subsets including lymphocytes, granulocytes and monocytes. The expression level was markedly different among individual dogs. These results indicated that the method applied in this study is useful for evaluating canine SIRT1 levels in PBMCs from dogs.