Dysfunctional fat cells, lipotoxicity and type 2 diabetes

The mitochondrial pyruvate carrier regulates adipose glucose partitioning in female mice

OBJECTIVE

The mitochondrial pyruvate carrier (MPC) occupies a critical node in intermediary metabolism, prompting interest in its utility as a therapeutic target for the treatment of obesity and cardiometabolic disease. Dysregulated nutrient metabolism in adipose tissue is a prominent feature of obesity pathophysiology, yet the functional role of adipose MPC has not been explored. We investigated whether the MPC shapes the adaptation of adipose tissue to dietary stress in female and male mice.

METHODS

The impact of pharmacological and genetic disruption of the MPC on mitochondrial pathways of triglyceride assembly (lipogenesis and glyceroneogenesis) was assessed in 3T3L1 adipocytes and murine adipose explants, combined with analyses of adipose MPC expression in metabolically compromised humans. Whole-body and adipose-specific glucose metabolism were subsequently investigated in male and female mice lacking adipocyte MPC1 (Mpc1AD-/-) and fed either standard chow, high-fat western style, or high-sucrose lipid restricted diets for 24 weeks, using a combination of radiolabeled tracers and GC/MS metabolomics.

RESULTS

Treatment with UK5099 or siMPC1 impaired the synthesis of lipids and glycerol-3-phosphate from pyruvate and blunted triglyceride accumulation in 3T3L1 adipocytes, whilst MPC expression in human adipose tissue was negatively correlated with indices of whole-body and adipose tissue metabolic dysfunction. Mature adipose explants from Mpc1AD-/- mice were intrinsically incapable of incorporating pyruvate into triglycerides. In vivo, MPC deletion restricted the incorporation of circulating glucose into adipose triglycerides, but only in female mice fed a zero fat diet, and this associated with sex-specific reductions in tricarboxylic acid cycle pool sizes and compensatory transcriptional changes in lipogenic and glycerol metabolism pathways. However, whole-body adiposity and metabolic health were preserved in Mpc1AD-/- mice regardless of sex, even under conditions of zero dietary fat.

CONCLUSIONS

These findings highlight the greater capacity for mitochondrially driven triglyceride assembly in adipose from female versus male mice and expose a reliance upon MPC-gated metabolism for glucose partitioning in female adipose under conditions of dietary lipid restriction.

Alterations in nonesterified free fatty acid trafficking rather than hyperandrogenism contribute to metabolic health in obese women with polycystic ovary syndrome

OBJECTIVE

To determine whether alterations in nonesterified fatty acid (NEFA) dynamics or degree of hyperandrogenism (HA) contribute to the difference in insulin sensitivity between women with metabolically healthy obese polycystic ovary syndrome (PCOS) (MHO-PCOS) and women with metabolically unhealthy obese PCOS (MUO-PCOS).

DESIGN

Prospective cross-sectional study.

SETTING

Tertiary-care academic center.

PATIENTS

One hundred twenty-five obese women with PCOS.

INTERVENTION

Consecutive obese (body mass index [BMI] ≥ 30 kg/m2) oligo-ovulatory women (n = 125) with PCOS underwent an oral glucose tolerance test and a subgroup of 16 participants underwent a modified frequently sampled intravenous glucose tolerance test to determine insulin-glucose and -NEFA dynamics.

MAIN OUTCOME MEASURES

Degree of insulin resistance (IR) in adipose tissue (AT) basally (Adipo-IR) and dynamically (the nadir in NEFA levels observed [NEFAnadir], the time it took for NEFA levels to reach nadir [TIMEnadir], and the percent suppression in plasma NEFA levels from baseline to nadir [%NEFAsupp]); peak lipolysis rate (SNEFA) and peak rate of NEFA disposal from plasma pool (KNEFA); whole-body insulin-glucose interaction (acute response of insulin to glucose [AIRg], insulin sensitivity index [Si], glucose effectiveness [Sg], and disposition index [Di]); and HA (hirsutism score, total and free testosterone levels, and dehydroepiandrosterone sulfate levels).

RESULTS

A total of 85 (68%) women were MUO-PCOS and 40 (32%) were MHO-PCOS using the homeostasis model of assessment of IR. Subjects with MUO-PCOS and MHO-PCOS did not differ in mean age, BMI, waist-to-hip ratio, HA, and lipoprotein levels. By a modified frequently sampled intravenous glucose tolerance test, eight women with MUO-PCOS had lesser Si, KNEFA, and the percent suppression in plasma NEFA levels from baseline to nadir (%NEFAsupp) and greater TIMEnadir, NEFAnadir, and baseline adipose tissue IR index (Adipo-IR) than eight subjects with MHO-PCOS, but similar fasting NEFA levels and SNEFA. Women with MUO-PCOS had a higher homeostasis model of assessment-β% and fasting insulin levels than women with MHO-PCOS. In bivalent analysis, Si correlated strongly and negatively with Adipo-IR and NEFAnadir, weakly and negatively with TIMEnadir, and positively with KNEFA and %NEFAsupp, in women with MUO-PCOS only.

CONCLUSION

Independent of age and BMI, women with MUO-PCOS have reduced NEFA uptake and altered insulin-mediated NEFA suppression, but no difference in HA, compared with women with MHO-PCOS. Altered insulin-mediated NEFA suppression, rather than HA or lipolysis rate, contributes to variations in insulin sensitivity among obese women with PCOS.

Sex-dependent adipose glucose partitioning by the mitochondrial pyruvate carrier

Objective

The mitochondrial pyruvate carrier (MPC) occupies a critical node in intermediary metabolism, prompting interest in its utility as a therapeutic target for the treatment of obesity and cardiometabolic disease. Dysregulated nutrient metabolism in adipose tissue is a prominent feature of obesity pathophysiology, yet the functional role of adipose MPC has not been explored. We investigated whether the MPC shapes the adaptation of adipose tissue to dietary stress in female and male mice.

Methods

The impact of pharmacological and genetic disruption of the MPC on mitochondrial pathways of triglyceride assembly (lipogenesis and glyceroneogenesis) was assessed in 3T3L1 adipocytes and murine adipose explants, combined with analyses of adipose MPC expression in metabolically compromised humans. Whole-body and adipose-specific glucose metabolism were subsequently investigated in male and female mice lacking adipocyte MPC1 (Mpc1AD-/-) and fed either standard chow, high-fat western style, or high-sucrose lipid restricted diets for 24 weeks, using a combination of radiolabeled tracers and GC/MS metabolomics.

Results

Treatment with UK5099 or siMPC1 impaired the synthesis of lipids and glycerol-3-phosphate from pyruvate and blunted triglyceride accumulation in 3T3L1 adipocytes, whilst MPC expression in human adipose tissue was negatively correlated with indices of whole-body and adipose tissue metabolic dysfunction. Mature adipose explants from Mpc1AD-/- mice were intrinsically incapable of incorporating pyruvate into triglycerides. In vivo, MPC deletion restricted the incorporation of circulating glucose into adipose triglycerides, but only in female mice fed a zero fat diet, and this associated with sex-specific reductions in tricarboxylic acid cycle pool sizes and compensatory transcriptional changes in lipogenic and glycerol metabolism pathways. However, whole-body adiposity and metabolic health were preserved in Mpc1AD-/- mice regardless of sex, even under conditions of zero dietary fat.

Conclusion

These findings highlight the greater capacity for mitochondrially driven triglyceride assembly in adipose from female versus male mice and expose a reliance upon MPC-gated metabolism for glucose partitioning in female adipose under conditions of dietary lipid restriction.

Effects of mitochondrial dysfunction on cellular function: Role in atherosclerosis

Atherosclerosis, an immunoinflammatory disease of medium and large arteries, is associated with life-threatening clinical events, such as acute coronary syndromes and stroke. Chronic inflammation and impaired lipoprotein metabolism are considered to be among the leading causes of atherosclerosis, while numerous risk factors, including arterial hypertension, diabetes mellitus, obesity, and aging, can contribute to the development of the disease. In recent years, emerging evidence has underlined the key role of mitochondrial dysfunction in the pathogenesis of atherosclerosis. Mitochondrial dysfunction is believed to result in an increase in reactive oxygen species, leading to oxidative stress, chronic inflammation, and intracellular lipid deposition, all of which can contribute to the pathogenesis of atherosclerosis. Critical cells, including endothelial cells, vascular smooth muscle cells, and macrophages, play an important role in atherosclerosis. Mitochondrial function is also involved in maintaining the normal function of these cells. To better understand the relationship between mitochondrial dysfunction and atherosclerosis, this review summarizes the findings of recent studies and discusses the role of mitochondrial dysfunction in the risk factors and critical cells of atherosclerosis. FACTS: OPEN QUESTIONS.

Untargeted metabolomics based on ultra-high performance liquid chromatography-mass spectrometry/MS reveals the lipid-lowering mechanism of taurine in hyperlipidemia mice

Introduction

Taurine has a prominent lipid-lowering effect on hyperlipidemia. However, a comprehensive analysis of the effects of taurine on endogenous metabolites in hyperlipidemia has not been documented. This study aimed to explore the impact of taurine on multiple metabolites associated with hyperlipidemia.

Methods

The hyperlipidemic mouse model was induced by high-fat diet (HFD). Taurine was administered via oral gavage at doses of 700  mg/kg/day for 14  weeks. Evaluation of body weight, serum lipid levels, and histopathology of the liver and adipose tissue was performed to confirm the lipid-lowering effect of taurine. Ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS)-based metabonomics analyses of serum, urine, feces, and liver, coupled with multivariate data analysis, were conducted to assess changes in the endogenous metabolites.

Results and discussion

Biochemical and histological examinations demonstrated that taurine administration prevented weight gain and dyslipidemia, and alleviated lipid deposition in the liver and adipose tissue in hyperlipidemic mice. A total of 76 differential metabolites were identified by UPLC-MS-based metabolomics approach, mainly involving BAs, GPs, SMs, DGs, TGs, PUFAs and amino acids. Taurine was found to partially prevent HFDinduced abnormalities in the aforementioned metabolites. Using KEGG database and MetaboAnalyst software, it was determined that taurine effectively alleviates metabolic abnormalities caused by HFD, including fatty acid metabolism, sphingolipid metabolism, glycerophospholipid metabolism, diacylglycerol metabolism, amino acid metabolism, bile acid and taurine metabolism, taurine and hypotaurine metabolism. Moreover, DGs, GPs and SMs, and taurine itself may serve as active metabolites in facilitating various anti-hyperlipidemia signal pathways associated with taurine. This study provides new evidence for taurine to prevent hyperlipidemia.

Mechanism of Obesity-Related Lipotoxicity and Clinical Perspective

The link between cellular exposure to fatty acid species and toxicity phenotypes remains poorly understood. However, structural characterization and functional profiling of human plasma free fatty acids (FFAs) analysis has revealed that FFAs are located either in the toxic cluster or in the cluster that is transcriptionally responsive to lipotoxic stress and creates genetic risk factors. Genome-wide short hairpin RNA screen has identified more than 350 genes modulating lipotoxicity. Hypertrophic adipocytes in obese adipose are both unable to expand further to store excess lipids in the diet and are resistant to the antilipolytic action of insulin. In addition to lipolysis, the inability of packaging the excess lipids into lipid droplets causes circulating fatty acids to reach toxic levels in non-adipose tissues. Deleterious effects of accumulated lipid in non-adipose tissues are known as lipotoxicity. Although triglycerides serve a storage function for long-chain non-esterified fatty acid and their products such as ceramide and diacylglycerols (DAGs), overloading of palmitic acid fraction of saturated fatty acids (SFAs) raises ceramide levels. The excess DAG and ceramide load create harmful effects on multiple organs and systems, inducing chronic inflammation in obesity. Thus, lipotoxic inflammation results in β cells death and pancreatic islets dysfunction. Endoplasmic reticulum stress stimuli induce lipolysis by activating cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and extracellular signal-regulated kinase (Erk) 1/2 signaling in adipocytes. However, palmitic acid-induced endoplasmic reticulum stress-c-Jun N-terminal kinase (JNK)-autophagy axis in hypertrophic adipocytes is a pro-survival mechanism against endoplasmic reticulum stress and cell death induced by SFAs. Endoplasmic reticulum-localized acyl-coenzyme A (CoA): glycerol-3-phosphate acyltransferase (GPAT) enzymes are mediators of lipotoxicity, and inhibiting these enzymes has therapeutic potential for lipotoxicity. Lipotoxicity increases the number of autophagosomes, which engulf palmitic acid, and thus suppress the autophagic turnover. Fatty acid desaturation promotes palmitate detoxification and storages into triglycerides. As therapeutic targets of glucolipotoxicity, in addition to caloric restriction and exercise, there are four different pharmacological approaches, which consist of metformin, glucagon-like peptide 1 (GLP-1) receptor agonists, peroxisome proliferator-activated receptor-gamma (PPARγ) ligands thiazolidinediones, and chaperones are still used in clinical practice. Furthermore, induction of the brown fat-like phenotype with the mixture of eicosapentanoic acid and docosahexaenoic acid appears as a potential therapeutic application for treatment of lipotoxicity.

In praise of pioglitazone: An economically efficacious therapy for type 2 diabetes and other manifestations of the metabolic syndrome

Pioglitazone improves glycaemic control, not only by lowering insulin resistance, but also by improving beta cell function. Because of the improved beta cell function the glycaemic control that occurs with pioglitazone is prolonged. Pioglitazone has positive effects not only on cardiac risk factors and surrogate measures of cardiovascular disease, it also lowers the incidence of cardiac events in patients with diabetes. The recurrence of transient ischaemic attack and ischaemic stroke is also reduced in non-diabetic, insulin-resistant subjects. Utilized at preclinical stages (but not later) of heart failure, pioglitazone improves diastolic function and avoids progression to heart failure. Pioglitazone, through suppression of atrial remodelling, also decreases the incidence of atrial fibrillation. The manifestations of diseases associated with insulin resistance (non-alcoholic steatohepatitis and polycystic ovary disease) are also improved with pioglitazone. Pioglitazone may possibly improve psoriasis and other dermopathies. Pioglitazone is therefore an inexpensive and efficacious drug for the insulin-resistant subject with diabetes that is underutilized because of biases that have evolved from the toxicities of other thiazolidinediones.

Precision nutrition for targeting pathophysiology of cardiometabolic phenotypes

Obesity is a heterogenous disease accompanied by a broad spectrum of cardiometabolic risk profiles. Traditional paradigms for dietary weight management do not address biological heterogeneity between individuals and have catastrophically failed to combat the global pandemic of obesity-related diseases. Nutritional strategies that extend beyond basic weight management to instead target patient-specific pathophysiology are warranted. In this narrative review, we provide an overview of the tissue-level pathophysiological processes that drive patient heterogeneity to shape distinct cardiometabolic phenotypes in obesity. Specifically, we discuss how divergent physiology and postprandial phenotypes can reveal key metabolic defects within adipose, liver, or skeletal muscle, as well as the integrative involvement of the gut microbiome and the innate immune system. Finally, we highlight potential precision nutritional approaches to target these pathways and discuss recent translational evidence concerning the efficacy of such tailored dietary interventions for different obesity phenotypes, to optimise cardiometabolic benefits.

Peroxisome proliferator-activated receptors as targets to treat metabolic diseases: Focus on the adipose tissue, liver, and pancreas

The world is experiencing reflections of the intersection of two pandemics: Obesity and coronavirus disease 2019. The prevalence of obesity has tripled since 1975 worldwide, representing substantial public health costs due to its comorbidities. The adipose tissue is the initial site of obesity impairments. During excessive energy intake, it undergoes hyperplasia and hypertrophy until overt inflammation and insulin resistance turn adipocytes into dysfunctional cells that send lipotoxic signals to other organs. The pancreas is one of the organs most affected by obesity. Once lipotoxicity becomes chronic, there is an increase in insulin secretion by pancreatic beta cells, a surrogate for type 2 diabetes mellitus (T2DM). These alterations threaten the survival of the pancreatic islets, which tend to become dysfunctional, reaching exhaustion in the long term. As for the liver, lipotoxicity favors lipogenesis and impairs beta-oxidation, resulting in hepatic steatosis. This silent disease affects around 30% of the worldwide population and can evolve into end-stage liver disease. Although therapy for hepatic steatosis remains to be defined, peroxisome proliferator-activated receptors (PPARs) activation copes with T2DM management. Peroxisome PPARs are transcription factors found at the intersection of several metabolic pathways, leading to insulin resistance relief, improved thermogenesis, and expressive hepatic steatosis mitigation by increasing mitochondrial beta-oxidation. This review aimed to update the potential of PPAR agonists as targets to treat metabolic diseases, focusing on adipose tissue plasticity and hepatic and pancreatic remodeling.

Obesity-related parameters in carriers of some BDNF genetic variants may depend on daily dietary macronutrients intake

Some common single-nucleotide polymorphisms of the brain-derived neurotrophic factor (BDNF) gene have been associated not only with the neurodegenerative diseases but also with some eating disorders. The aim of this study was to assess the possible differences in the obesity-related and glucose metabolism parameters between some BDNF genotypes', that may depend on the daily energy and macronutrients intake. In 484 adult participants we performed the anthropometric measurements, body composition analysis, and body fat distribution. The daily dietary intake was assessed using the 3-day food intake diaries. Blood glucose and insulin concentrations were measured at fasting and during oral glucose tolerance tests. Moreover, the visceral adipose tissue/subcutaneous adipose tissue (VAT/SAT) ratio and homeostatic model assessment of insulin resistance were calculated. We noted that participants carrying the GG genotype had lower skeletal muscle mass and fat free mass (FFM) when carbohydrate intake was > 48%, whereas they presented higher fat-free mass (FFM), and surprisingly higher total cholesterol and LDL-C concentrations when daily fiber intake was > 18 g. Moreover, in these subjects we noted higher waist circumference, BMI, and fasting glucose and insulin concentrations, when > 18% of total daily energy intake was delivered from proteins, and higher VAT content and HDL-C concentrations when > 30% of energy intake was derived from dietary fat. Our results suggest that glucose homeostasis and obesity-related parameters in carriers of some common variants of BDNF gene, especially in the GG (rs10835211) genotype carriers, may differ dependently on daily energy, dietary macronutrients and fiber intake.

Steered Molecular Dynamics Simulations Study on FABP4 Inhibitors

Ordinary small molecule de novo drug design is time-consuming and expensive. Recently, computational tools were employed and proved their efficacy in accelerating the overall drug design process. Molecular dynamics (MD) simulations and a derivative of MD, steered molecular dynamics (SMD), turned out to be promising rational drug design tools. In this paper, we report the first application of SMD to evaluate the binding properties of small molecules toward FABP4, considering our recent interest in inhibiting fatty acid binding protein 4 (FABP4). FABP4 inhibitors (FABP4is) are small molecules of therapeutic interest, and ongoing clinical studies indicate that they are promising for treating cancer and other diseases such as metabolic syndrome and diabetes.

Pathophysiology of Prediabetes, Diabetes, and Diabetic Remission in Cats

Diabetes mellitus (DM) has a heterogenous cause, and the exact pathogenesis differs between patients. Most diabetic cats have a cause similar to human type 2 DM but, in some, DM is associated with underlying conditions, such as hypersomatotropism, hyperadrenocorticism, or administration of diabetogenic drugs. Predisposing factors for feline DM include obesity, reduced physical activity, male sex, and increasing age. Gluco(lipo)toxicity and genetic predisposition also likely play roles in pathogenesis. Prediabetes cannot be accurately diagnosed in cats at the current time. Diabetic cats can enter remission, but relapses are common, as these cats might have ongoing, abnormal glucose homeostasis.

ox-LDL induces autophagy-mediated apoptosis by suppressing secretagogin-regulated autophagic flux in pancreatic β-cells

Lipotoxicity has been shown to induce the loss of functional β-cell mass and lead to type 2 diabetes, but the mechanism remains unknown. In this study, we aim to explore the role of secretagogin (SCGN) in lipotoxicity-induced β-cell injury. Our results indicate that ox-LDL treatment leads to autophagic cell death, as evidenced by decreased cell viability, aggravated cell apoptosis, and the accumulation of the p62 protein in MIN6 cells. LysoTracker Red staining, TEM and mRFP-GFP-LC3 assays demonstrate that autophagic flux is blocked in ox-LDL-treated MIN6 cells. Intriguingly, SCGN is significantly decreased in MIN6 cells under lipotoxic conditions. Additionally, siRNA-guided SCGN knockdown blocks autophagic flux triggered by rapamycin, while SCGN restoration alleviates autophagic flux retardation and mitigates cell apoptosis. The physical interaction between SCGN and SNAP29 is validated by bioinformatics analysis, coimmunoprecipitation assay and SCGN knockdown test. Downregulation of SCGN expression reduces the interaction of these two proteins. Taken together, our results indicate that ox-LDL treatment induces apoptotic β-cell death by blocking autophagic flux dependent on SCGN downregulation. SCGN administration prevents lipotoxic β-cell injury and may be a potential therapeutic strategy to promote β-cell expansion in type 2 diabetes.

Ligand Growing Experiments Suggested 4-amino and 4-ureido pyridazin-3(2H)-one as Novel Scaffold for FABP4 Inhibition

Fatty acid binding protein (FABP4) inhibitors are of synthetic and therapeutic interest and ongoing clinical studies indicate that they may be a promise for the treatment of cancer, as well as other diseases. As part of a broader research effort to develop more effective FABP4 inhibitors, we sought to identify new structures through a two-step computing assisted molecular design based on the established scaffold of a co-crystallized ligand. Novel and potent FABP4 inhibitors have been developed using this approach and herein we report the synthesis, biological evaluation and molecular docking of the 4-amino and 4-ureido pyridazinone-based series.

Targeting pancreatic β cells for diabetes treatment

Insulin is a life-saving drug for patients with type 1 diabetes; however, even today, no pharmacotherapy can prevent the loss or dysfunction of pancreatic insulin-producing β cells to stop or reverse disease progression. Thus, pancreatic β cells have been a main focus for cell-replacement and regenerative therapies as a curative treatment for diabetes. In this Review, we highlight recent advances toward the development of diabetes therapies that target β cells to enhance proliferation, redifferentiation and protection from cell death and/or enable selective killing of senescent β cells. We describe currently available therapies and their mode of action, as well as insufficiencies of glucagon-like peptide 1 (GLP-1) and insulin therapies. We discuss and summarize data collected over the last decades that support the notion that pharmacological targeting of β cell insulin signalling might protect and/or regenerate β cells as an improved treatment of patients with diabetes.

Differential Effects of Amount, Intensity, and Mode of Exercise Training on Insulin Sensitivity and Glucose Homeostasis: A Narrative Review

As type 2 diabetes remains a leading cause of morbidity and mortality, identifying the most appropriate preventive treatment early in the development of disease is an important public health matter. In general, lifestyle interventions incorporating exercise and weight loss via caloric restriction improve cardiometabolic risk by impacting several key markers of insulin sensitivity and glucose homeostasis. However, variations in the effects of specific types of exercise interventions on these markers have led to conflicting results surrounding the optimal amount, intensity, and mode of exercise for optimal effects. Moreover, the addition of weight loss via caloric restriction to exercise interventions appears to differentially impact changes in body composition, metabolism, and insulin sensitivity compared to exercise alone. Determining the optimal amount, intensity, and mode of exercise having the most beneficial impact on glycemic status is both: (1) clinically important to provide guidelines for appropriate exercise prescription; and (2) physiologically important to understand the pathways by which exercise-with and without weight loss-impacts glycemic status to enhance precision lifestyle medicine. Thus, the purposes of this narrative review are to: (1) summarize findings from the three Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) randomized trials regarding the differential effects of exercise amount, intensity, and mode on insulin action and glucose homeostasis markers; and (2) compare the STRRIDE findings to other published dose-response exercise trials in order to piece together the various physiologic pathways by which specific exercise interventions-with or without weight loss-impact glycemic status.

Adipocyte fatty acid binding protein 4 (FABP4) inhibitors. An update from 2017 to early 2022

The fatty acid binding protein 4 (FABP4) is a protein predominantly expressed in macrophages and adipose tissue, where it regulates fatty acids storage and lipolysis and is an essential mediator of inflammation. Small molecule inhibitors of FABP4 have attracted interest following the recent publications of beneficial pharmacological effects of these compounds for the treatment of metabolic syndrome and, more recently, for other pathologies. Since the synthesis of the BMS309403, one of the first selective and effective FABP4 inhibitors, hundreds of other inhibitors have been synthesized (i.e., derivatives of niacin, quinoxaline, aryl-quinoline, bicyclic pyridine, urea, aromatic compounds and other novel heterocyclic compounds). This review updates the recently reported (2017 to early 2022) molecules as adipocyte fatty acid binding protein 4 inhibitors.

Panax notoginseng extract and total saponin suppress diet-induced obesity and endoplasmic reticulum stress in epididymal white adipose tissue in mice

Background

Investigation on protective effects of Panax notoginseng against obesity and its related mechanisms is incomplete. Present study aimed to investigate the potential anti-obesity effect of the total saponins (PNS) and ethanolic extract of P. notoginseng (PNE).

Methods

Six-week-old male C57BL/6J mice received 45% kcal fat diet for 12 weeks to induce obesity. Oral administration of PNS and PNE at 20 mg/kg/day was applied for the last 4 weeks in the obese mice. Lipid profile was determined by ELISA. Histological examination was performed in liver and fat tissues. Protein levels were measured by Western blot.

Results

PNS and PNE did not cause weight loss. PNE but not PNS decreased the mass of epididymal and retroperitoneal white adipose tissue, accompanied by a reduction in adipocyte hypertrophy. PNS and PNE improved lipid profile by reducing the concentrations of triglyceride, total cholesterol and low-density lipoprotein cholesterol in plasma or liver samples. PNS and PNE also relieved fatty liver in obese mice. PNS and PNE inhibited expression and phosphorylation of endoplasmic reticulum (ER) stress-responsive proteins in hypertrophic adipose tissue.

Conclusions

PNS and PNE can regulate ER stress-mediated apoptosis and inflammation to alleviate obesity.

Prospective dietary radical scavengers: Boon in Pharmacokinetics, overcome insulin obstruction via signaling cascade for absorption during impediments in metabolic disorder like Diabetic Mellitus

Diabetes mellitus is a metabolic disorder which is characterized based on the blood glucose level. This can be due to the lack of efficiency of utilizing insulin or lack of production of insulin. There are numerous therapies and medications which are available for the treatment of this disease which can reduce the risk of diabetes. But there is no permanent cure found. Nutritional antioxidants show a foremost role in sustaining the homeostasis of the oxidative equilibrium. They have imparted their electron donor efficacy in preventing aging and in cancer. Vitamin C, E, β-carotene, carotenoids, polyphenols and selenium have been appraised as antioxidant constituents in the human diet nourishment. This paper emphasizes on the role of antioxidants which help in reducing or maintaining the level of glucose in the body. Antioxidants are substances that reduces the damages to the cells caused by free radicals. The available treatment and medications and how the supplementation of antioxidants is different from them is also discussed. Different type of antioxidants and their treatment in curing the disease is further focused in this paper.

Graphical abstract

Burden of Type 2 Diabetes and Associated Cardiometabolic Traits and Their Heritability Estimates in Endogamous Ethnic Groups of India: Findings From the INDIGENIUS Consortium

To assess the burden of type 2 diabetes (T2D) and its genetic profile in endogamous populations of India given the paucity of data, we aimed to determine the prevalence of T2D and estimate its heritability using family-based cohorts from three distinct Endogamous Ethnic Groups (EEGs) representing Northern (Rajasthan [Agarwals: AG]) and Southern (Tamil Nadu [Chettiars: CH] and Andhra Pradesh [Reddys: RE]) states of India. For comparison, family-based data collected previously from another North Indian Punjabi Sikh (SI) EEG was used. In addition, we examined various T2D-related cardiometabolic traits and determined their heritabilities. These studies were conducted as part of the Indian Diabetes Genetic Studies in collaboration with US (INDIGENIUS) Consortium. The pedigree, demographic, phenotypic, covariate data and samples were collected from the CH, AG, and RE EEGs. The status of T2D was defined by ADA guidelines (fasting glucose ≥ 126 mg/dl or HbA1c ≥ 6.5% and/or use of diabetes medication/history). The prevalence of T2D in CH (N = 517, families = 21, mean age = 47y, mean BMI = 27), AG (N = 530, Families = 25, mean age = 43y, mean BMI = 27), and RE (N = 500, Families = 22, mean age = 46y, mean BMI = 27) was found to be 33%, 37%, and 36%, respectively, Also, the study participants from these EEGs were found to be at increased cardiometabolic risk (e.g., obesity and prediabetes). Similar characteristics for the SI EEG (N = 1,260, Families = 324, Age = 51y, BMI = 27, T2D = 75%) were obtained previously. We used the variance components approach to carry out genetic analyses after adjusting for covariate effects. The heritability (h2) estimates of T2D in the CH, RE, SI, and AG were found to be 30%, 46%, 54%, and 82% respectively, and statistically significant (P ≤ 0.05). Other T2D related traits (e.g., BMI, lipids, blood pressure) in AG, CH, and RE EEGs exhibited strong additive genetic influences (h2 range: 17% [triglycerides/AG and hs-CRP/RE] - 86% [glucose/non-T2D/AG]). Our findings highlight the high burden of T2D in Indian EEGs with significant and differential additive genetic influences on T2D and related traits.

Host Metabolic Changes during Mycobacterium Tuberculosis Infection Cause Insulin Resistance in Adult Mice

Tuberculosis (TB) is a highly infectious bacterial disease that primarily attacks the lungs. TB is manifested either as latent TB infection (LTBI) or active TB disease, the latter posing a greater threat to life. The risk of developing active TB disease from LTBI is three times higher in individuals with type 2 diabetes mellitus (T2DM). The association between TB and T2DM is becoming more prominent as T2DM is rapidly increasing in settings where TB is endemic. T2DM is a chronic metabolic disorder characterized by elevated blood glucose, insulin resistance, and relative insulin deficiency. Insulin resistance and stress-induced hyperglycemia have been shown to be increased by TB and to return to normal upon treatment. Previously, we demonstrated that adipocytes (or fat tissue) regulate pulmonary pathology, inflammation, and Mycobacterium tuberculosis (Mtb) load in a murine model of TB. Metabolic disturbances of adipose tissue and/or adipocyte dysfunction contribute to the pathogenesis of T2DM. Thus, pathological adipocytes not only regulate pulmonary pathology, but also increase the risk for T2DM during TB infection. However, the cellular and molecular mechanisms driving the interaction between hyperglycemia, T2DM and TB remain poorly understood. Here, we report the impact of Mtb infection on the development of insulin resistance in mice fed on a regular diet (RD) versus high-fat diet (HFD) and, conversely, the effect of hyperglycemia on pulmonary pathogenesis in juvenile and adult mouse models. Overall, our study demonstrated that Mtb persists in adipose tissue and that Mtb infection induces irregular adipocyte lipolysis and loss of fat cells via different pathways in RD- and HFD-fed mice. In RD-fed mice, the levels of TNFα and HSL (hormone sensitive lipase) play an important role whereas in HFD-fed mice, ATGL (adipose triglyceride lipase) plays a major role in regulating adipocyte lipolysis and apoptosis during Mtb infection in adult mice. We also showed that Mtb infected adult mice that were fed an RD developed insulin resistance similar to infected adult mice that were overweight due to a HFD diet. Importantly, we found that a consequence of Mtb infection was increased lipid accumulation in the lungs, which altered cellular energy metabolism by inhibiting major energy signaling pathways such as insulin, AMPK and mToR. Thus, an altered balance between lipid metabolism and glucose metabolism in adipose tissue and other organs including the lungs may be an important component of the link between Mtb infection and subsequent metabolic syndrome.

The Potential of Dietary Bioactive Compounds against SARS-CoV-2 and COVID-19-Induced Endothelial Dysfunction

COVID-19 is an endothelial disease. All the major comorbidities that increase the risk for severe SARS-CoV-2 infection and severe COVID-19 including old age, obesity, diabetes, hypertension, respiratory disease, compromised immune system, coronary artery disease or heart failure are associated with dysfunctional endothelium. Genetics and environmental factors (epigenetics) are major risk factors for endothelial dysfunction. Individuals with metabolic syndrome are at increased risk for severe SARS-CoV-2 infection and poor COVID-19 outcomes and higher risk of mortality. Old age is a non-modifiable risk factor. All other risk factors are modifiable. This review also identifies dietary risk factors for endothelial dysfunction. Potential dietary preventions that address endothelial dysfunction and its sequelae may have an important role in preventing SARS-CoV-2 infection severity and are key factors for future research to address. This review presents some dietary bioactives with demonstrated efficacy against dysfunctional endothelial cells. This review also covers dietary bioactives with efficacy against SARS-CoV-2 infection. Dietary bioactive compounds that prevent endothelial dysfunction and its sequelae, especially in the gastrointestinal tract, will result in more effective prevention of SARS-CoV-2 variant infection severity and are key factors for future food research to address.

The Insulin-Sensitizer Pioglitazone Remodels Adipose Tissue Phospholipids in Humans

The insulin-sensitizer pioglitazone exerts its cardiometabolic benefits in type 2 diabetes (T2D) through a redistribution of body fat, from ectopic and visceral areas to subcutaneous adipose depots. Whereas excessive weight gain and lipid storage in obesity promotes insulin resistance and chronic inflammation, the expansion of subcutaneous adipose by pioglitazone is associated with a reversal of these immunometabolic deficits. The precise events driving this beneficial remodeling of adipose tissue with pioglitazone remain unclear, and whether insulin-sensitizers alter the lipidomic composition of human adipose has not previously been investigated. Using shotgun lipidomics, we explored the molecular lipid responses in subcutaneous adipose tissue following 6months of pioglitazone treatment (45mg/day) in obese humans with T2D. Despite an expected increase in body weight following pioglitazone treatment, no robust effects were observed on the composition of storage lipids (i.e., triglycerides) or the content of lipotoxic lipid species (e.g., ceramides and diacylglycerides) in adipose tissue. Instead, pioglitazone caused a selective remodeling of the glycerophospholipid pool, characterized by a decrease in lipids enriched for arachidonic acid, such as plasmanylethanolamines and phosphatidylinositols. This contributed to a greater overall saturation and shortened chain length of fatty acyl groups within cell membrane lipids, changes that are consistent with the purported induction of adipogenesis by pioglitazone. The mechanism through which pioglitazone lowered adipose tissue arachidonic acid, a major modulator of inflammatory pathways, did not involve alterations in phospholipase gene expression but was associated with a reduction in its precursor linoleic acid, an effect that was also observed in skeletal muscle samples from the same subjects. These findings offer important insights into the biological mechanisms through which pioglitazone protects the immunometabolic health of adipocytes in the face of increased lipid storage.

Exercise ameliorates insulin resistance and improves ASK1-mediated insulin signalling in obese rats

Increasing evidence reveals that physical exercise is an efficient therapeutical approach in the treatment of insulin resistance (IR) and related metabolic diseases. However, the potential beneficial effects of exercise on insulin resistance and its underlying mechanisms remain unclear. Recent findings elucidated the negative role of ASK1 in repressing the glucose uptake through JNK1‐IRS1‐Akt signalling in liver. Thus, a detailed investigation of the effect of ASK1‐mediated insulin signalling on exercise‐mediated improvement of insulin sensitivity and its underlying mechanism was implemented in this study. Using a high‐fat diet‐induced IR rat model of chronic or acute swimming exercise training, we here showed that body weight and visceral fat mass were significantly reduced after chronic exercise. Moreover, chronic exercise reduced serum FFAs levels and hepatic triglyceride content. Both chronic and acute exercise promoted glucose tolerance and insulin sensitivity. Meanwhile, both chronic and acute exercise decreased ASK1 phosphorylation and improved JNK1‐IRS1‐Akt signalling. Furthermore, exercise training decreased CFLAR, CREG and TRAF1 protein levels in liver of obese rats, which are positive regulator of ASK1 activity. These results suggested that swimming exercise demonstrated to be an effective ameliorator of IR through the regulation of ASK1‐mediated insulin signalling and therefore, could present a prospective therapeutic mean towards the treatment of IR and several metabolic diseases based on IR, containing NAFLD and type Ⅱ diabetes.

Regulations of Free Fatty Acids and Diabetic Parameters in Drug Naïve Subjects with Type 2 Diabetes Treated with Canagliflozin Monotherapy

The objective of this study is to investigate the regulations of FFA with canagliflozin in relation to metabolic parameters. Drug naïve subjects with T2DM were administered 50-100 mg/day canagliflozin monotherapy (n=70) for 3 months. Significant correlations between the changes of (Δ) FFA and Δadipo-IR (R=0.496), but no correlations between ΔFFA and ΔHOMA-R were observed. The subjects were divided into three groups with similar numbers according to Δ FFA: group A: highest tertile: (ΔFFA=38.7%, n=23); group B: intermediate tertile: (ΔFFA=2%, n=23); group C: lowest tertile: (ΔFFA=-36%, n=24). Metabolic parameters were compared between group A and group C. At baseline, FFA was higher in group C than group A (p<0.002). Greater degrees of HbA1c reduction and increases of insulin were observed in group C than group A (both p<0.05). In group A, significant reductions of BMI (-2.6%) and HOMA-R (-30%) were seen. In group C, significant reductions of non-HDL-C (-6.2%), UA (-7.6%) or adipo-IR (-28.7%), and increases of HOMA-B (+85.6%) were observed. Taken together, 1) certain population treated with canagliflozin showed decreased FFA. 2) beta-cell function increased while atherogenic cholesterol, UA and adipo-IR decreased in those with reduced FFA. Better glycemic efficacies were seen in these populations. 3) body weight and whole body insulin resistance (HOMA-R) significantly decreased in those with elevated FFA. 4) FFA is linked to adipose insulin resistance (adipo-IR), while it does not appear to impact whole body insulin resistance (HOMA-R).

Age and Sex: Impact on adipose tissue metabolism and inflammation

Age associated chronic inflammation is a major contributor to diseases with advancing age. Adipose tissue function is at the nexus of processes contributing to age-related metabolic disease and mediating longevity. Hormonal fluctuations in aging potentially regulate age-associated visceral adiposity and metabolic dysfunction. Visceral adiposity in aging is linked to aberrant adipogenesis, insulin resistance, lipotoxicity and altered adipokine secretion. Age-related inflammatory phenomena depict sex differences in macrophage polarization, changes in T and B cell numbers, and types of dendritic cells. Sex differences are also observed in adipose tissue remodeling and cellular senescence suggesting a role for sex steroid hormones in the regulation of the adipose tissue microenvironment. It is crucial to investigate sex differences in aging clinical outcomes to identify and better understand physiology in at-risk individuals. Early interventions aimed at targets involved in adipose tissue adipogenesis, remodeling and inflammation in aging could facilitate a profound impact on health span and overcome age-related functional decline.

Rationale for the use of metformin and exercise to counteract statin-associated side effects

INTRODUCTION

Statins are the most widely prescribed drugs for lowering low-density lipoprotein cholesterol (LDL-C) and reducing cardiovascular morbidity and mortality. They are usually well-tolerated, but have two main safety concerns: statin-associated muscle symptoms (SAMS) and new-onset type 2 diabetes (NOD).

METHODS

A PubMed search was carried out using the following key words were used: statins, statin-associated muscle symptoms, statin myalgia, statin-associated diabetes, metformin and statins, exercise and statins.

RESULTS

Mitochondrial damage and muscle atrophy are likely the central mechanisms producing SAMS, whereas decreased glucose transport, fatty acid oxidation and insulin secretion are likely involved in the development of NOD. Metformin and exercise training share many pathways that could potentially contrast SAMS and NOD. Clinical evidence also supports the combination of statins with metformin and exercise.

CONCLUSION

This combination appears attractive both from a clinical and an economical viewpoint, since all three therapies are highly cost-effective and their combination could result in diabetes and cardiovascular disease prevention.

Antioxidative Potentials of Incretin-Based Medications: A Review of Molecular Mechanisms

Glucagon-like peptide 1 receptor agonists and dipeptidyl-peptidase 4 inhibitors are medications used for managing diabetes, mimicking the metabolic effects of incretin hormones. Recent evidence suggests that these medications have antioxidative potentials in the diabetic milieu. The pathophysiology of most diabetic complications involves oxidative stress. Therefore, if incretin-based antidiabetic medications can alleviate the free radicals involved in oxidative stress, they can potentially provide further therapeutic effects against diabetic complications. However, the molecular mechanisms by which these medications protect against oxidative stress are not fully understood. In the current review, we discuss the potential molecular mechanisms behind these pharmacologic agents' antioxidative properties.

Bone Marrow-Derived Mesenchymal Stem Cells Restored High-Fat-Fed Induced Hyperinsulinemia in Rats at Early Stage of Type 2 Diabetes Mellitus

Numerous studies have proposed the transplantation of mesenchymal stem cells (MSCs) in the treatment of typical type 2 diabetes mellitus (T2DM). We aimed to find a new strategy with MSC therapy at an early stage of T2DM to efficiently prevent the progressive deterioration of organic dysfunction. Using the high-fat-fed hyperinsulinemia rat model, we found that before the onset of typical T2DM, bone marrow-derived MSCs (BM-MSCs) significantly attenuated rising insulin with decline in glucose as well as restored lipometabolic disorder and liver dysfunction. BM-MSCs also favored the histological structure recovery and proliferative capacity of pancreatic islet cells. More importantly, BM-MSC administration successfully reversed the abnormal expression of insulin resistance-related proteins including GLUT4, phosphorylated insulin receptor substrate 1, and protein kinase Akt and proinflammatory cytokines IL-6 and TNFα in liver. These findings suggested that MSCs transplantation during hyperinsulinemia could prevent most potential risks of T2DM for patients.

Effects of different oxygen tensions on differentiated human preadipocytes lipid storage and mobilisation

Adipose tissue expansion has been suggested to impair oxygen (O₂) diffusion in the adipose tissue and cause hypoxia. This study aimed at characterising the effects of hypoxia on adipocyte lipid storage and mobilisation functions. Human preadipocytes were exposed to different O₂ tensions (3, 10 and 21%) either acutely for 24 h after differentiation (acute exposure) or during differentiation (14d, chronic hypoxia). Lipoprotein lipase (LPL) activity was decreased dose-dependently by both acute and chronic hypoxia (p < .05). Acute exposure to 3, and 10% O₂ stimulated the expression of lipid storage gene, while chronic exposure to 3% O₂ inhibited the expression of genes involved in lipid storage and mobilisation (p < .05). Acute hypoxia dose-dependently stimulated basal lipolysis. Conversely, chronic hypoxia did not affect basal lipolysis but significantly decreased isoproterenol-stimulated lipolysis (p < .05). In conclusion, the effects of hypoxia on human adipocyte lipid storage and mobilisation functions are complex but could favour ectopic fat deposition.

The effect of pilates on metabolic control and oxidative stress of diabetics type 2 - A randomized controlled clinical trial

INTRODUCTION

The Pilates method is an approach to body and mind exercises that has as its foundation the gain of stability, strength and flexibility, and the work of muscular control, posture and breathing, which can generate repercussions on oxidative stress and ROS production, it is expected that Pilates can satisfactorily influence glycemic and oxidative stress reduction in elderly diabetes.

AIM

To analyze the effect of a Pilates protocol on variables indicative of metabolic control and oxidative stress in patients with Type 2 Diabetes Mellitus.

METHOD

Randomized clinical trial in type 2 diabetics enrolled in Hiperdia Parnaíba. A Pilates protocol was performed for 8 weeks, with 2 weekly consultations. The tested variables were: blood glucose, glycated hemoglobin, lipid profile, C-reactive protein and malondialdehyde. ANOVA tests, correlation of Wilcoxon, Friedman and Spearman, were used, with a significance level of 5%.

RESULTS

44 diabetics participated in the study (intervention group: 22; control: 22), with a mean age of 61.23 ± 8.49years, the majority being female (77.3%), married (59.1%), literate (31.8%), with an average BMI of 26.96 ± 4.35 kg/m². When analyzing the effects of the protocol, there was a significant reduction in glycated hemoglobin (p = 0.002) and oxidative stress (p = 0.004) in the intervention group, however, there were no differences in fasting glucose (p = 0.055) and in the profile lipid, expressed by the total cholesterol (p = 0.654), HDL (p = 0.591), LDL (p = 0.564) and triglycerides (0.192). There was a moderate positive correlation between oxidative stress and glycated hemoglobin (r = 0.44, p = 0.000).

CONCLUSION

The exercise protocol based on the Pilates method produced a reduction in glycated hemoglobin and oxidative stress.

Insulin Action, Glucose Homeostasis and Free Fatty Acid Metabolism: Insights From a Novel Model

Glucose and free fatty acids (FFA) are essential nutrients that are both partly regulated by insulin. Impaired insulin secretion and insulin resistance are hallmarks of aberrant glucose disposal, and type 2 diabetes (T2DM). In the current study, a novel model of FFA kinetics is proposed to estimate the role insulin action on FFA lipolysis and oxidation allowing estimation of adipose tissue insulin sensitivity (S_IFFA ). Twenty-five normal volunteers were recruited for the current study. To participate, volunteers had to be less than 40 years of age and have a body mass index (BMI) < 30 kg/m², and be free of medical comorbidity. The proposed model of FFA kinetics was used to analyze the data derived from the insulin-modified FSIGT. Mean fractional standard deviations of the parameter estimates were all less than 20%. Standardized residuals of the fit of the model to the FFA temporal data were randomly distributed, with only one estimated point lying outside the 2-standard deviation range, suggesting an acceptable fit of the model to the FFA data. The current study describes a novel one-compartment non-linear model of FFA kinetics during an FSIGT that provides an FFA metabolism insulin sensitivity parameter (S_IFFA ). Furthermore, the models suggest a new role of glucose as the modulator of FFA disposal. Estimates of S_IFFA confirmed previous findings that FFA metabolism is more sensitive to changes in insulin than glucose metabolism. Novel derived indices of insulin sensitivity of FFA (S_IFFA ) were correlated with minimal model indices. These associations suggest a cooperative rather than competitive interplay between the two primary nutrients (glucose and FFA) and allude to the FFA acting as the buffer, such that glucose homeostasis is maintained.

Associations Between Serum Free Fatty Acid Levels and Incident Diabetes in a 3-Year Cohort Study

PURPOSE

High circulating free fatty acid (FFA) is associated with the development of diabetes. This study was designed to evaluate longitudinal associations between FFA levels, changes in FFA levels, and mean FFA levels and incident diabetes.

PARTICIPANTS AND METHODS

This 3-year cohort study was conducted in Ningyang between 2011 and 2014. Serum FFA, fasting blood glucose (FPG), 2-hour postprandial blood glucose (2hPG), and glycosylated hemoglobin (HbA1c) levels were measured at baseline and at the end of follow-up. A multivariate stepwise logistic regression model was used to evaluate associations between serum FFA levels in various groups and the risk of incident diabetes.

RESULTS

Of the 2905 individuals without baseline diabetes, 290 developed diabetes by the 3-year follow-up. With increasing baseline FFA levels, the mean FPG, 2hPG, and HbA1c levels, and the prevalence of diabetes at the end of follow-up increased. The trend of FPG and HbA1c increase was not statistically significant. Higher baseline FFA levels were not significantly associated with greater risk of incident diabetes. However, longitudinal changes in serum FFA levels showed that individuals with serum FFA levels from normal to high (OR = 2.956, 95% CI: 2.089-4.184) or from high to high (OR = 3.343, 95% CI: 2.300-4.857) had greater risk of incident diabetes compared with those with normal to normal FFA levels. Similarly, individuals with ΔFFA ≥ 0 mmol/L (OR = 1.762, 95% CI: 1.373-2.262) or high mean serum FFA levels (OR = 2.120, 95% CI: 1.620-2.775) were at higher risk of incident diabetes than those with ΔFFA < 0 mmol/L or normal mean serum FFA levels.

CONCLUSION

The longitudinal status of serum FFA levels, including chronic increases and sustained high levels, was more closely associated with high risk of incident diabetes than was high baseline FFA levels.

Exercise training improves adipose tissue metabolism and vasculature regardless of baseline glucose tolerance and sex

INTRODUCTION

We investigated the effects of a supervised progressive sprint interval training (SIT) and moderate-intensity continuous training (MICT) on adipocyte morphology and adipose tissue metabolism and function; we also tested whether the responses were similar regardless of baseline glucose tolerance and sex.

RESEARCH DESIGN AND METHODS

26 insulin-resistant (IR) and 28 healthy participants were randomized into 2-week-long SIT (4-6×30 s at maximum effort) and MICT (40-60 min at 60% of maximal aerobic capacity (VO2peak)). Insulin-stimulated glucose uptake and fasting-free fatty acid uptake in visceral adipose tissue (VAT), abdominal and femoral subcutaneous adipose tissues (SATs) were quantified with positron emission tomography. Abdominal SAT biopsies were collected to determine adipocyte morphology, gene expression markers of lipolysis, glucose and lipid metabolism and inflammation.

RESULTS

Training increased glucose uptake in VAT (p<0.001) and femoral SAT (p<0.001) and decreased fatty acid uptake in VAT (p=0.01) irrespective of baseline glucose tolerance and sex. In IR participants, training increased adipose tissue vasculature and decreased CD36 and ANGPTL4 gene expression in abdominal SAT. SIT was superior in increasing VO2peak and VAT glucose uptake in the IR group, whereas MICT reduced VAT fatty acid uptake more than SIT.

CONCLUSIONS

Short-term training improves adipose tissue metabolism both in healthy and IR participants independently of the sex. Adipose tissue angiogenesis and gene expression was only significantly affected in IR participants.

Differential Expression of Ormdl Genes in the Islets of Mice and Humans with Obesity

The orosomucoid-like (Ormdl) proteins play a critical role in sphingolipid homeostasis, inflammation, and ER stress, all of which are associated with obesity and βcell dysfunction. However, their roles in β cells and obesity remain unknown. Here, we show that islets from overweight/obese human donors displayed marginally reduced ORMDL1-2 expression, whereas ORMDL3 expression was significantly downregulated compared with islets from lean donors. In contrast, Ormdl3 was substantially upregulated in the islets of leptin-deficient obese (ob/ob) mice compared with lean mice. Treatment of ob/ob mice and their islets with leptin markedly reduced islet Ormld3 expression. Ormdl3 knockdown in a β cell line induced expression of pro-apoptotic markers, which was rescued by ceramide synthase inhibitor fumonisin B1. Our results reveal differential expression of Ormdl3 in the islets of a mouse model and humans with obesity, highlight the potential effect of leptin in this differential regulation, and suggest a role for Ormdl3 in β cell apoptosis.

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Islets of overweight/obese human donors display markedly reduced ORMDL3 expression

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Ormdl3 expression was significantly upregulated in the islets of ob/ob mice

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Leptin treatment markedly reduced Ormld3 expression in the islets of ob/ob mice

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Fumonisin B1 restores increased apoptotic marker levels induced by Ormdl3 silencing

Development of novel human in vitro vascularized adipose tissue model with functional macrophages

Inflammation has been proven significant factor in development of type 2 diabetes. So far, most of the adipose tissue related research has been performed in animals, mainly rodent models. The relevance of translation of animal results to humans is questionable. However, in vitro model with relevant human cell source, such as human adipose tissue stromal cells (hASC), can be developed and should be utilized for human adipose tissue research. We developed in vitro models of human adipose tissue utilizing hASC, endothelial cells and monocytes/macrophages. By isolating endothelial cells and macrophages from same adipose tissue as hASC, we were able to provide method for constructing personalized models of adipose tissue. With these models, we studied the effect of macrophages on adipogenesis and protein secretion, with and without vasculature. The models were analyzed for immunocytochemical markers, cell number, triglyceride accumulation and protein secretion. We found that lipid accumulation was greater in adipocytes in the presence of macrophages. Interferon gamma increased this difference between adipocyte culture and Adipocyte-Macrophage co-culture. Protein secretion was affected more by macrophages when vasculature was not present compared to the mild effect when vasculature was present. The vascularized adipose model with macrophages is valuable tool for human adipose tissue research, especially for the personalized medicine approaches; for choosing the right treatments and for studying rare medical conditions.

Genetic predisposition in type 2 diabetes: A promising approach toward a personalized management of diabetes

Diabetes mellitus, also known simply as diabetes, has been described as a chronic and complex endocrine metabolic disorder that is a leading cause of death across the globe. It is considered a key public health problem worldwide and one of four important non-communicable diseases prioritized for intervention through world health campaigns by various international foundations. Among its four categories, Type 2 diabetes (T2D) is the commonest form of diabetes accounting for over 90% of worldwide cases. Unlike monogenic inherited disorders that are passed on in a simple pattern, T2D is a multifactorial disease with a complex etiology, where a mixture of genetic and environmental factors are strong candidates for the development of the clinical condition and pathology. The genetic factors are believed to be key predisposing determinants in individual susceptibility to T2D. Therefore, identifying the predisposing genetic variants could be a crucial step in T2D management as it may ameliorate the clinical condition and preclude complications. Through an understanding the unique genetic and environmental factors that influence the development of this chronic disease individuals can benefit from personalized approaches to treatment. We searched the literature published in three electronic databases: PubMed, Scopus and ISI Web of Science for the current status of T2D and its associated genetic risk variants and discus promising approaches toward a personalized management of this chronic, non-communicable disorder.

Intra-Abdominal Fat and High Density Lipoprotein Cholesterol Are Associated in a Non-Linear Pattern in Japanese-Americans

BACKGROUND

We describe the association between high density lipoprotein cholesterol (HDL-C) concentration and computed tomography (CT)-measured fat depots.

METHODS

We examined the cross-sectional associations between HDL-C concentration and intra-abdominal (IAF), abdominal subcutaneous (SCF), and thigh fat (TF) areas in 641 Japanese-American men and women. IAF, SCF, and TF were measured by CT at the level of the umbilicus and mid-thigh. The associations between fat area measurements and HDL-C were examined using multivariate linear regression analysis adjusting for age, sex, diabetes family history, homeostasis model assessment of insulin resistance (HOMA-IR), and body mass index (BMI). Non-linearity was assessed using fractional polynomials.

RESULTS

Mean±standard deviation of HDL-C concentration and IAF in men and women were 1.30±0.34 mg/dL, 105±55.3 cm², and 1.67±0.43 mg/dL, 74.4±46.6 cm² and differed significantly by gender for both comparisons (P<0.001). In univariate analysis, HDL-C concentration was significantly associated with CT-measured fat depots. In multivariate analysis, IAF was significantly and non-linearly associated with HDL-C concentration adjusted for age, sex, BMI, HOMA-IR, SCF, and TF (IAF: β=-0.1012, P<0.001; IAF²: β=0.0008, P<0.001). SCF was also negatively and linearly associated with HDL-C (β=-0.4919, P=0.001).

CONCLUSION

HDL-C does not linearly decline with increasing IAF in Japanese-Americans. A more complex pattern better fits this association.

Antidiabetic Properties of Curcumin I: Evidence from In Vitro Studies

Type 2 diabetes mellitus (T2DM) is a growing metabolic disease characterized by insulin resistance and hyperglycemia. Current preventative and treatment strategies for T2DM and insulin resistance lack in efficacy resulting in the need for new approaches to prevent and manage/treat the disease better. In recent years, epidemiological studies have suggested that diets rich in fruits and vegetables have beneficial health effects including protection against insulin resistance and T2DM. Curcumin, a polyphenol found in turmeric, and curcuminoids have been reported to have antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, neuroprotective, immunomodulatory and antidiabetic properties. The current review (I of II) summarizes the existing in vitro studies examining the antidiabetic effects of curcumin, while a second (II of II) review summarizes evidence from existing in vivo animal studies and clinical trials focusing on curcumin’s antidiabetic properties.

Antidiabetic Properties of Curcumin II: Evidence from In Vivo Studies

Type 2 diabetes mellitus (T2DM) is a growing metabolic disease characterized by insulin resistance and hyperglycemia. Current preventative and treatment approaches to insulin resistance and T2DM lack in efficacy, resulting in the need for new approaches to prevent and treat the disease. In recent years, epidemiological studies have suggested that diets rich in fruits and vegetables have beneficial health effects, including protection against insulin resistance and T2DM. Curcumin, a polyphenol found in turmeric, and curcuminoids have been reported to have antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, neuroprotective, immunomodulatory and antidiabetic properties. The current review (II of II) summarizes the existing in vivo studies examining the antidiabetic effects of curcumin.

Heparanase upregulation from adipocyte associates with inflammation and endothelial injury in diabetic condition

Background

Diabetes Mellitus (DM) is one of the metabolic diseases which leads to fatty tissue injury, and consequently inducing lipotoxicity and cellular senescence. This condition contributes to endothelial dysfunction with chronic inflammation and organ damage. Heparanase which has a role in disrupting endothelial surface layer (glycocalyx) may promote endothelial Nitric oxide synthase (eNOS) reduction and inflammation. However, its relationship with DM and organ injury has not been fully elucidated yet. This study aimed to determine how heparanase from fatty tissue may contribute to endothelial dysfunction and inflammation in patients with hyperglycemia and in a hyperglycemia model in rats.

Methods

This population study with a cross-sectional design was conducted with 28 subjects without diagnosis and medication of DM. Fasting blood glucose levels, lipid profile, heparanase protein, MCP-1 protein and HbA1c were quantified. In vivo study was performed with a diabetic model in Wistar rats induced with streptozotocin 60 mg/kg body weight by single intraperitoneal injection. Rats were euthanized after 1 month (DM1 group, n = 6), 2 months (DM2 group, n = 6) and 4 months (DM4 group, n = 6). White Adipose Tissue (WAT) was harvested from visceral fat. Real Time and Reverse Transcriptase-PCR (RT-PCR) was done to quantify expressions of heparanase, MCP-1, eNOS, IL-6 and p-16 (senescence). Immunostaining was performed to localize MCP-1 and macrophage (CD68). Western blot tests were used to examine eNOS, MCP-1 and heparanase protein expression.

Results

This study revealed associations between blood glucose levels with higher HbA1c, LDL, cholesterol, heparanase and MCP-1. The in vivo study also revealed lipid levels as the source of Heparanase and MCP-1 mRNA and protein expressions. This finding was associated with inflammation, cellular senescence and macrophage infiltration in fat tissue based on immunostaining and qRT-PCR analysis. RT-PCR revealed significantly lower expression of eNOS and higher expression of IL-6 in DM groups compared to the control group.

Conclusion

Heparanase upregulation in fat tissue was associated with endothelial injury and inflammation in hyperglycemia conditions.

Anti-inflammatory potentials of incretin-based therapies used in the management of diabetes

GLP-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase 4 inhibitors (DPP-4i) are two classes of antidiabetic agents used in the management of diabetes based on incretin hormones. There is emerging evidence that they have anti-inflammatory effects. Since most long-term complications of diabetes have a background of chronic inflammation, these agents may be beneficial against diabetic complications not only due to their hypoglycemic potential but also via their anti-inflammatory effects. However, the exact molecular mechanisms by which GLP-1RAs and DPP-4i exert their anti-inflammatory effects are not clearly understood. In this review, we discuss the potential molecular pathways by which these incretin-based therapies exert their anti-inflammatory effects.

miR-22-3p is involved in gluconeogenic pathway modulated by 3,5-diiodo-L-thyronine (T2)

The 3,5-diiodo-L-thyronine (T2) has emerged as an active iodothyronine and its beneficial effects on glucose metabolism including glucose tolerance and insulin resistance is well established. However, little is known about its molecular mechanisms. Given the emerging importance of microRNAs in various metabolic diseases, in this study a possible link between the effects of T2 on glucose metabolism and miRNA expression was investigated by using an in vivo model in which T2 was administered in rats receiving a high fat diet, a condition known to impair glucose homeostasis. The results showed that T2-treated rats had a better tolerance to glucose load and a better performance at the insulin tolerance test in comparison to high fat diet animals. Interestingly, in the serum of the animals treated with T2 there was a general decrease of miRNAs with miR-22a-3p, miR-34c-5p and miR-33a-3p significantly downregulated. Furthermore, miR-22a-3p had the largest variation pointing toward its preeminent role in T2 metabolic effect. In fact, in liver there was an up-regulation of its target (Transcription Factor 7) Tcf7, which had an important impact on gluconeogenesis. This study provide, for the first time, evidences that miRNAs are involved in the effects exerted by T2 on glucose homeostasis.

Computational Tools in the Discovery of FABP4 Ligands: A Statistical and Molecular Modeling Approach

Small molecule inhibitors of adipocyte fatty-acid binding protein 4 (FABP4) have received interest following the recent publication of their pharmacologically beneficial effects. Recently, it was revealed that FABP4 is an attractive molecular target for the treatment of type 2 diabetes, other metabolic diseases, and some type of cancers. In past years, hundreds of effective FABP4 inhibitors have been synthesized and discovered, but, unfortunately, none have reached the clinical research phase. The field of computer-aided drug design seems to be promising and useful for the identification of FABP4 inhibitors; hence, different structure- and ligand-based computational approaches have been used for their identification. In this paper, we searched for new potentially active FABP4 ligands in the Marine Natural Products (MNP) database. We retrieved 14,492 compounds from this database and filtered through them with a statistical and computational filter. Seven compounds were suggested by our methodology to possess a potential inhibitory activity upon FABP4 in the range of 97–331 nM. ADMET property prediction was performed to validate the hypothesis of the interaction with the intended target and to assess the drug-likeness of these derivatives. From these analyses, three molecules that are excellent candidates for becoming new drugs were found.

Mild Physiologic Hyperglycemia Induces Hepatic Insulin Resistance in Healthy Normal Glucose-Tolerant Participants

CONTEXT

Chronic hyperglycemia worsens skeletal muscle insulin resistance and β-cell function. However, the effect of sustained physiologic hyperglycemia on hepatic insulin sensitivity is not clear.

OBJECTIVE

To examine the effect of sustained physiologic hyperglycemia (similar to that observed in patients with type 2 diabetes) on endogenous (primarily reflecting hepatic) glucose production (EGP) in healthy individuals.

DESIGN

Volunteers participated in a three-step hyperinsulinemic (10, 20, 40 mU/m2 per minute) euglycemic clamp before and after a 48-hour glucose infusion to increase plasma glucose concentration by ∼40 mg/dL above baseline. EGP was measured with 3-3H-glucose before and after chronic glucose infusion.

PARTICIPANTS

Sixteen persons with normal glucose tolerance [eight with and eight without a family history (FH) of diabetes] participated in the study.

MAIN OUTCOME MEASURE

EGP.

RESULTS

Basal EGP increased following 48 hours of glucose infusion (from a mean ± SEM of 2.04 ± 0.08 to 3.06 ± 0.29 mg/kgffm⋅ min; P < 0.005). The hepatic insulin resistance index (basal EGP × fasting plasma insulin) markedly increased following glucose infusion (20.1 ± 1.8 to 51.7 ± 6.6; P < 0.005) in both FH+ and FH- subjects.

CONCLUSION

Sustained physiologic hyperglycemia for as little as 48 hours increased the rate of basal hepatic glucose production and induced hepatic insulin resistance in health persons with normal glucose tolerance, providing evidence for the role of glucotoxicity in the increase in hepatic glucose production in type 2 diabetes.

Gastrin analogue administration adds no significant glycaemic benefit to a glucagon-like peptide-1 receptor agonist acutely or after washout of both analogues

AIM

To determine if a 4-week course of 14 mg weekly GLP-1 agonist LY2428757 combined with 3 mg or 2 mg daily gastrin analogue TT223 (LY+TT223) results in long-term glycaemic changes.

MATERIALS AND METHODS

Patients with in adequately-controlled type 2 diabetes mellitus ±metformin (N=151) were randomized to a 4-week course of LY+TT223 (3 mg), LY+TT223 (2 mg), LY+TT223 placebo (LY-only) or LY placebo+TT223 placebo (placebo). The primary objective was change in HbA1c from baseline to 5 month safter completion of therapy (i.e. at 6 months) and safety and tolerability with LY+TT223 versus LY-only.

RESULTS

LY groups showed HbA1c reductions during the active treatment phase. These did not persist during follow-up phase. Combining TT223 with LY did not result in additional glycaemic effects during treatment or follow-up. At 6 months, LSM ± SE for change in HbA1c from baseline was: LY+TT223 (3 mg): -0.1 ± 0.2%; LY+TT223 (2 mg): 0.1 ± 0.2%; LY-only: -0.2 ± 0.2%; placebo: 0.04 ± 0.2%. Secondary analyses were consistent with primary results. LY+TT223 was not superior to LY for other time points or end points, including insulin secretory response to mixed meal tolerance tests. The most common adverse events (nausea and vomiting) were more frequent with LY+TT223 versus LY-only. The safety profile was consistent with previous findings.

CONCLUSION

GLP-1+gastrin combination therapy did not improve glycaemic control versus GLP-1 alone.

Evaluation of testis hormonal and histopathological alterations in type I and type II diabetic rats

BACKGROUND

Diabetes is a devastating metabolic disease that causes long-term damage to various organs. An important leading complication of diabetes is a degenerative effect on the reproductive system including infertility and gonadal dysfunction. This study aimed to evaluate the effects of experimental type I and II diabetes on the levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone.

METHODS

Male Wistar rats were randomly divided into four separate groups: (1) type I diabetes (T1DM), (2) type II diabetes (T2DM), (3) cetrorelix acetate-treated nondiabetic control group, and (4) normal untreated group (n = 6). T1DM was experimentally induced by a single injection of alloxan (135 mg/kg) while T2DM was induced by feeding the animals with drinking water enriched with fructose (10%). Cetrorelix acetate (100 mg/kg, intraperitoneal for 1 week) treatment group was used as a positive control. All rats were killed and blood and testes were collected after 8 weeks of the study. The effects of induced diabetes on the levels of blood glucose and insulin were assessed. The levels of sex hormones and insulin were determined by radioimmunoassay. Histological staining was used to check abnormal patterns of testicular morphology, the diameter of seminiferous tubules, testicular diameter, and germinal layer thickness.

RESULTS

A significant reduction in the testosterone, FSH, and LH levels were observed in T1DM, T2DM, and also in cetrorelix acetate-treated groups. Analysis of testicular histology sections revealed significantly reduced thickness of cell layer in T1DM and cetrorelix acetate-treated groups compared with the T2DM group. In T2DM, the cell numbers, the thickness of cell layer, the diameter of seminiferous tubules, and weight of testicles were slightly increased. In contrast, total tubules of empty seminiferous increased significantly in T1D and cetrorelix treated groups compared with the control group.

CONCLUSION

Overall, diabetes can induce hypothalamus-pituitary-gonad axis dysfunction, affects hormonal secretion, and causes histological damage to testes, collectively leading to deleterious effects on male fertility.

Lower cardiovagal tone and baroreflex sensitivity associated with hepatic insulin resistance and promote cardiovascular disorders in Tibetan minipigs induced by a high fat and high cholesterol diet

AIMS

A long-term high-fat/cholesterol (HFC) diet leads to hepatic insulin resistance (IR), which is associated with autonomic dysfunction and cardiovascular diseases risk increasing. However, whether this occurs in Tibetan minipigs remains unknown. We tested that a long-term HFC diet caused hepatic IR and promote cardiovascular disorders in Tibetan minipigs, and are associated with the reduction of cardiovagal tone and baroreflex sensitivity (BRS).

METHODS

Male Tibetan minipigs were fed either a standard diet or a HFC diet, and were euthanized at 12 weeks. Thereafter, the minipigs were tested for biochemical blood indices, glucose tolerance, blood pressure, heart rate variability (HRV), BRS, and insulin receptor substrate (IRS)-associated gene and protein expression levels, as well as cardiac function.

RESULTS

HFC-fed minipigs developed IR by increasing body weight, total cholesterol, fasting blood glucose and insulin levels, and nonesterified fatty acid (NEFA) and high sensitive C-reactive protein (hs-CRP) levels, glucose intolerance. Increased adipose cell size, hepatic fat deposition, malondialdehyde (MDA) content and NEFA level, down-regulation of IRS1, IRS2, PI3K, Akt, p-Akt, Glut2 and PGC1ɑ expression concomitant with up-regulation of mTOR, GSK3β, TNF-ɑ, FOXO1, p-mTOR and p-p70S6K expression in the liver tissue, as well as hypertension and left ventricular diastolic dysfunction were observed in HFC-fed minipigs. HRV parameters and BRS values were further significantly reduced. Furthermore, multiple linear regression analysis showed that the development of hepatic IR toward cardiovascular disease was associated with low HFnu, RMSSD, BRS and LV -dp/dtmax, high NEFA, high hepatic TG content.

CONCLUSION

These data suggest that HFC-fed Tibetan minipigs develop hepatic IR and promote cardiovascular disorders, and are associated with lower cardiovagal tone and BRS.