Lipotoxicity of beta-cells in obesity and in other causes of fatty acid spillover

Type 2 diabetes and cardiovascular conditions prediction in individuals with metabolic syndrome-associated lipoprotein lipase gene (LPL) single nucleotide polymorphisms (SNPs)

OBJECTIVE

Metabolic syndrome (MetS) is predictive of increased risk of type 2 diabetes (T2D) and cardiovascular conditions (CVC). Lipoprotein lipase gene (LPL) single nucleotide polymorphisms (SNPs) may be of importance to the eventual diagnosis of T2D and CVC. This study aimed to predict the diagnosis of T2D and CVC amongst individuals with LPL SNPs rs268, rs11542065, rs116403115, rs118204057, rs118204061, rs144466625, and rs547644955.

METHODS

This is a retrospective study using the UK Biobank data. Variables associated with MetS, T2D and CVC were selected from the data set. The total number of subjects in the cohort was 12,872 (mean age 56 years ± 8.1, 90.0 % were of British ethnicity, and 53.9 % were females). Logistic regression was used to assess whether the T2D and CVC can be predicted based on the presence of LPL SNPs and some of the clinical measures.

RESULTS

Prediction models using clinical parameters showed good area under the curve (AUC) for prediction of T2D and CVC diagnosis (in receiver operating characteristic (ROC) analysis, area under the curve (AUC) = 0.959 for T2D, AUC = 0.772 for CVC). The addition of Polygenic Risk Scores (PRS/s) showed an improvement for diagnosis of both (AUC = 0.961 and 0.790 for TD and CVC, respectively). Further addition of SNPs showed more increase in AUC (AUC = 0.965 and 0.837 for T2D and CVC, respectively). The additive effect of the PRSs and LPL SNPs was more pronounced in the CVC than in the T2D model. The variant that had major significance for both T2D and CVC diagnoses was rs547644955 (AUC 1.0 and 0.910, respectively). The SNPs rs116403115 and rs118204057 both had an AUC of 1.0 for T2D diagnosis.

CONCLUSION

The prediction of T2D and CVC diagnoses with the use of clinically available factors may be enhanced with the addition of PRSs and SNPs, including LPL SNPs, which may have implications for stratified or personalised approaches for disease prevention or treatment.

Emerging biomarkers in type 2 diabetes mellitus

Diabetes mellitus is a chronic condition caused by high blood glucose resulting from insufficient insulin production or cellular resistance to insulin action or both. It is one of the fastest-growing public health concerns worldwide. Development of long-term nephropathy, retinopathy, neuropathy, and cardiovascular disease are some of the complications commonly associated with poor blood glycemic control. Type 2 diabetes mellitus (T2DM), the most prevalent type of diabetes, accounts for around 95 % of all cases globally. Although middle-aged or older adults are more likely to develop T2DM, its prevalence has grown in children and young people due to increased obesity, sedentary lifestyle and poor nutrition. Furthermore, it is believed that more than 50 % of cases go undiagnosed annually. Routine screening is essential to ensure early detection and reduce risk of life-threatening complications. Herein, we review traditional biomarkers and highlight the ongoing pursuit of novel and efficacious biomarkers driven by the objective of achieving early, precise and prompt diagnoses. It is widely acknowledged that individual biomarkers will inevitably have certain limitations necessitating the need for integrating multiple markers in screening.

Association between non-high-density lipoprotein cholesterol and type 2 diabetes: a systematic review and meta-analysis of cohort studies

Non-high-density lipoprotein cholesterol (non-HDL), a more readily available and reliable lipid parameter, is unclear in its association with type 2 diabetes (T2D). Previous studies assessing the relationship between non-HDL and T2D risk remains inconsistent results. We performed a meta-analysis to systematically evaluate this association. The PubMed, EMBASE, Medline, Web of Science, and Cochrane Library databases were systematically searched to find articles on "non-HDL" and "T2D" from inception to December 6, 2023. A random-effects model was used to calculate the effect estimates and 95% confidence intervals. Subgroup analyses and univariate Meta-regression were performed to explore sources of heterogeneity. The main exposure and outcome were non-HDL and T2D, respectively, in the general population. A total of 8 studies included 251,672 participants who met the inclusion criteria for this study. Meta-analysis showed that higher non-HDL increased the risk of T2D compared with the lower non-HDL group (total effect size: 1.16; 95% CI 1.079-1.251, p < 0.001). Subgroup analyses and Meta-regression of the association between non-HDL and T2D were not affected by region, proportion of men, sample size, or adjustment for confounders (including BMI, hypertension, waist circumference, and family history of diabetes). Higher non-HDL may be associated with an increased risk of T2D. Large prospective cohort studies are needed to validate these findings, and further studies are required in order to elucidate the underlying pathophysiologic mechanisms underlying the association between non-HDL and T2D.

Mechanisms and risk factors of metabolic syndrome in children and adolescents

Metabolic syndrome (MetS) is a complex disorder characterized by abdominal obesity, elevated blood pressure, hyperlipidemia, and elevated fasting blood glucose levels. The diagnostic criteria for MetS in adults are well-established, but there is currently no consensus on the definition in children and adolescents. The etiology of MetS is believed to involve a complex interplay between genetic predisposition and environmental factors. While genetic predisposition explains only a small part of MetS pathogenesis, modifiable environmental risk factors play a significant role. Factors such as maternal weight during pregnancy, children's lifestyle, sedentariness, high-fat diet, fructose and branched-chain amino acid consumption, vitamin D deficiency, and sleep disturbances contribute to the development of MetS. Early identification and treatment of MetS in children and adolescents is crucial to prevent the development of chronic diseases later in life. In this review we discuss the latest research on factors contributing to the pathogenesis of MetS in children, focusing on non-modifiable and modifiable risk factors, including genetics, dysbiosis and chronic low-grade inflammation.

Role of hydrogen sulfide in the regulation of lipid metabolism: Implications on cardiovascular health

The World Health Organization (WHO) defines obesity as an urgency for health and a social emergency. Today around 39 % of people is overweight, of these over 13 % is obese. It is well-consolidated that the adipose cells are deputy to lipid storage under caloric excess; however, despite the classical idea that adipose tissue has exclusively a passive function, now it is known to be deeply involved in the regulation of systemic metabolism in physiological as well as under obesogenic conditions, with consequences on cardiovascular health. Beside two traditional types of adipose cells (white and brown), recently the beige one has been highlighted as the consequence of the healthy remodeling of white adipocytes, confirming their metabolic adaptability. In this direction, pharmacological, nutraceutical and nutrient-based approaches are addressed to positively influence inflammation and metabolism, thus contributing to reduce the obese-associated cardiovascular risk. In this scenario, hydrogen sulfide emerges as a new mediator that may regulate crucial targets involved in the regulation of metabolism. The current evidence demonstrates that hydrogen sulfide may induce peroxisome proliferator activated receptor γ (PPARγ), a crucial mediator of adipogenesis, inhibit the phosphorylation of perlipin-1 (plin-1), a protein implicated in the lipolysis, and finally promote browning process, through the release of irisin from skeletal muscle. The results summarized in this review suggest an important role of hydrogen sulfide in the regulation of metabolism and in the prevention/treatment of obese-associated cardiovascular diseases and propose new insight on the putative mechanisms underlying the release of hydrogen sulfide or its biosynthesis, delineating a further exciting field of application.

Triglycerides/HDL cholesterol ratio and type 2 diabetes incidence: Panasonic Cohort Study 10

BACKGROUND

Previous studies have investigated the association between the ratio of triglycerides (TG) to high-density lipoprotein cholesterol (HDL-C) and the incidence of diabetes in adults and discovered that a high TG/HDL-C ratio was linked to an elevated risk of new-onset diabetes. However, the comparison of predicting diabetes development among lipid profiles including the TG/HDL-C ratio, and the ratio of TG/HDL-C cut-off value has received limited attention. We examined the relationship between diabetes onset and the TG/HDL-C ratio in addition to the applicable cut-off value for predicting diabetes onset.

METHODS

This study included 120,613 participants from the health examination database at Panasonic Corporation from 2008 to 2017. Cox regression analysis employing multivariable models was used to investigate the association between lipid profiles, particularly the ratio of TG/HDL-C and the development of type 2 diabetes (T2D). The multivariable model was adjusted for age, sex, BMI, systolic blood pressure, plasma glucose levels after fasting, smoking status, and exercise habits. Areas under time-dependent receiver operating characteristic (ROC) curves (AUCs) were employed to assess the prediction performance and cut-off values of each indicator. A fasting plasma glucose level of 126 mg/dL, a self-reported history of diabetes, or usage of antidiabetic medicines were used to identify T2D.

RESULTS

During the course of the study, 6,080 people developed T2D. The median follow-up duration was 6.0 (3-10) years. Multivariable analysis revealed that the ratio of TG/HDL-C (per unit, HR; 1.03 [95% CI 1.02-1.03]) was substantially linked to the risk of incident T2D. AUC and cut-off points for the ratio of TG/HDL-C for T2D development after 10 years were 0.679 and 2.1, respectively. Furthermore, the AUC of the ratio of TG/HDL-C was considerably larger compared to that of LDL-C, HDL-C, and TG alone (all P < 0.001). We discovered an interaction effect between sex, BMI, and lipid profiles in subgroup analysis. Females and participants having a BMI of < 25 kg/m2 showed a higher correlation between lipid profile levels and T2D onset.

CONCLUSIONS

The ratio of TG/HDL-C was found to be a stronger predictor of T2D development within 10 years than LDL-C, HDL-C, or TG, indicating that it may be useful in future medical treatment support.

The Role of PPARγ Gene Polymorphisms, Gut Microbiota in Type 2 Diabetes: Current Progress and Future Prospects

Over the past decade, there has been a significant increase in studies investigating the relationship between the polymorphisms of the Peroxisome Proliferator-Activated Receptor gamma (PPARγ) gene and Type 2 Diabetes (T2D). PPARγ, a critical transcription factor, plays a central role in lipid metabolism, insulin resistance, and inflammatory response. Concurrently, the influence of gut microbiota on the development of T2D has gained increasing attention, especially their role in affecting host metabolism, such as lipid metabolism and the PPARγ signaling pathway. This review provides a comprehensive analysis of recent studies on PPARγ gene polymorphisms and their association with T2D, with a specific emphasis on the implications of gut microbiota and their interaction with PPARγ pathways. We also discuss the potential of manipulating gut microbiota and targeting PPARγ gene polymorphisms in T2D management. By deepening our understanding of these relationships, we aim to pave the way for novel preventative and therapeutic strategies for T2D.

Obesity phenotypes and cardiovascular risk: From pathophysiology to clinical management

Obesity epidemic reached the dimensions of a real global health crisis with more than one billion people worldwide living with obesity. Multiple obesity-related mechanisms cause structural, functional, humoral, and hemodynamic alterations with cardiovascular (CV) deleterious effects. A correct assessment of the cardiovascular risk in people with obesity is critical for reducing mortality and preserving quality of life. The correct identification of the obesity status remains difficult as recent evidence suggest that different phenotypes of obesity exist, each one associated with different degrees of CV risk. Diagnosis of obesity cannot depend only on anthropometric parameters but should include a precise assessment of the metabolic status. Recently, the World Heart Federation and World Obesity Federation provided an action plan for management of obesity-related CV risk and mortality, stressing for the instauration of comprehensive structured programs encompassing multidisciplinary teams. In this review we aim at providing an updated summary regarding the different obesity phenotypes, their specific effects on CV risk and differences in clinical management.

Association between hypertriglyceridemic-waist phenotype and circadian syndrome risk: a longitudinal cohort study

Recently, circadian syndrome (CircS) has been proposed as a new predictor of cardiometabolic risk. We aimed to investigate the relationship between the hypertriglyceridemic-waist phenotype and its dynamic status with CircS in China. We conducted a two-stage study based on the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2015. Multivariate logistic regression models in cross-sectional analysis and Cox proportional hazards regression models in longitudinal analysis were used to estimate the associations of hypertriglyceridemic-waist phenotypes with CircS and its components. We then applied multiple logistic regression analysis to evaluate the odds ratios (ORs) and 95% confidence intervals (CIs) for CircS risk by transformation into the hypertriglyceridemic-waist phenotype. A total of 9863 participants were included in the cross-sectional analysis and 3884 participants in the longitudinal analysis. Compared with normal waist circumference (WC) and normal triglyceride (TG) level (NWNT), CircS risk was increased with enlarged WC and high TG level (EWHT) (hazard ratio (HR) 3.87 [95% CI: 2.38, 5.39]). Similar results were observed in subgroup analyses by sex, age, smoking status, and drinking status. During follow-up, CircS risk was increased in group K (stable EWNT during follow-up) (OR 9.97 [95% CI: 6.41, 15.49]) compared with group A (stable NWNT during follow-up), while group L (baseline enlarged WC and normal TG level transformed to follow-up EWHT) had the highest risk of CircS (OR 116.07 [95% CI: 72.77, 185.14]). In conclusion, the hypertriglyceridemic-waist phenotype and its dynamic status were associated with the risk of developing CircS in Chinese adults.

Loss of CtBP2 may be a mechanistic link between metabolic derangements and progressive impairment of pancreatic β cell function

The adaptive increase in insulin secretion in early stages of obesity serves as a safeguard mechanism to maintain glucose homeostasis that cannot be sustained, and the eventual decompensation of β cells is a key event in the pathogenesis of diabetes. Here we describe a crucial system orchestrated by a transcriptional cofactor CtBP2. In cultured β cells, insulin gene expression is coactivated by CtBP2. Global genomic mapping of CtBP2 binding sites identifies a key interaction between CtBP2 and NEUROD1 through which CtBP2 decompacts chromatin in the insulin gene promoter. CtBP2 expression is diminished in pancreatic islets in multiple mouse models of obesity, as well as human obesity. Pancreatic β cell-specific CtBP2-deficient mice manifest glucose intolerance with impaired insulin secretion. Our transcriptome analysis highlights an essential role of CtBP2 in the maintenance of β cell integrity. This system provides clues to the molecular basis in obesity and may be targetable to develop therapeutic approaches.

Association of Hyper-Triglyceridemic Waist Phenotype and Diabetic Vascular Complication in the Chinese Population

Background

Diabetic vascular complications are the leading cause of crippling and death of diabetic patients and seriously affect patients' quality of life. It is essential to control the risk factors contributing to vascular complications in patients with Type 2 diabetes (T2DM). This study aimed to examine the association between hyper-triglyceridemic waist phenotype (HWP) and the risk of vascular complication index of diabetes in T2DM patients.

Methods

The participants with type 2 diabetes mellitus in this study registered at the National Metabolic Management Center (MMC) of Beijing Luhe Hospital from June 2017 to June 2021. Data were collected by trained personnel according to the protocol. The questionnaire containing information on demographic characteristics and lifestyle factors (including alcohol drinking and cigarette smoking et al) was administered by trained interviewers. Logistic regression analysis assessing the associations between the hyper-triglyceridemic waist phenotype and vascular complication index of diabetes. In addition, the subgroup analysis was performed by age, sex, HbA1c, hypertension or not, and education level.

Results

After data cleaning, a total of 3221 participants with T2DM were enrolled. The median (IQR) duration of diabetes was 47.00 (3.00, 125.00) months. Compared to the participants in the Normal triglycerides level and Normal waist circumference group (NTNW), those in the Elevated triglycerides level and Enlarged waist circumference group (HTGW) have a higher risk of CKD-related vascular complications; the OR of decreased estimated glomerular filtration rate (GFR) and elevated urinary albumin creatinine ratio (UACR) were 2.21 (95% CI:1.32-3.82) and 2.18 (95% CI:1.69-2.81), respectively. Moreover, compared to the participants in the NTNW group, the ORs of the decreased ankle-brachial index (ABI) and elevated Brachial-ankle pulse wave velocity (baPWV) were 2.24 (95% CI:1.38-3.80) and 1.63 (95% CI:1.28-2.06) in the HTGW group.

Conclusion

In summary, there was an association between hyper-triglyceridemic waist phenotype and diabetic vascular complications in the Chinese population.

Metabolic-associated fatty liver disease increases the risk of end-stage renal disease in patients with biopsy-confirmed diabetic nephropathy: a propensity-matched cohort study

AIMS

To investigate the relationship between metabolic-associated fatty liver disease (MAFLD) and end-stage renal disease (ESRD) in patients with biopsy-confirmed diabetic nephropathy (DN).

METHODS

A total of 316 participants with biopsy-confirmed DN between January 2008 and December 2019 were retrospectively assessed. Kaplan-Meier curve and Cox proportional hazard models were used to compare the risk of incident ESRD in 50 patients with MAFLD and 50 patients without MAFLD, after using propensity score matching (PSM) to address the imbalances of sex, age, baseline-estimated glomerular filtration rate, serum albumin, 24-h urine protein, hemoglobin and systolic blood pressure.

RESULTS

During the median follow-up period of 3 years, there were 19 ESRD outcome events (19%) in PSM cohort. Kaplan-Meier curve analysis suggested that renal survival significantly deteriorated in patients with MAFLD versus those without MAFLD (p = 0.021). Additionally, the hazard ratios (95% confidence interval) of MAFLD were 3.12 (1.09-8.95, p = 0.035), 3.36 (1.09-10.43, p = 0.036), 3.66 (1.22-10.98, p = 0.021), 4.25 (1.34-13.45, p = 0.014), 3.11 (1.08-8.96, p = 0.035) and 5.84 (1.94-18.5, p = 0.003) after adjustment for six models, including demographic, clinical and pathological characteristics as well as medication use at the time of renal biopsy, respectively. Besides, patients with higher liver fibrosis score had a greater possibility of ESRD, comparing to those with lower liver fibrosis score (p = 0.002).

CONCLUSIONS

MAFLD increases the risk of incident ESRD in patients with biopsy-proven DN. Further research is needed to determine whether treatment targeting MAFLD improves the prognosis of DN.

Growth hormone treatment does not augment the anti-diabetic effects of liraglutide in UCD-T2DM rats

INTRODUCTION

The incretin hormone glucagon-like peptide-1 (GLP-1) slows gastric emptying, increases satiety and enhances insulin secretion. GLP-1 receptor agonists, such as liraglutide, are used therapeutically in humans to improve glycaemic control and delay the onset of type 2 diabetes mellitus (T2DM). In UCD-T2DM rats, a model of polygenic obesity and insulin resistance, we have previously reported that daily liraglutide administration delayed diabetes onset by >4 months. Growth hormone (GH) may exert anti-diabetic effects, including increasing β-cell mass and insulin secretion, while disrupting GH signalling in mice reduces both the size and number of pancreatic islets. We therefore hypothesized that GH supplementation would augment liraglutide's anti-diabetic effects.

METHODS

Male UCD-T2DM rats were treated daily with GH (0.3 mg/kg) and/or liraglutide (0.2 mg/kg) from 2 months of age. Control (vehicle) and food-restricted (with food intake matched to liraglutide-treated rats) groups were also studied. The effects of treatment on diabetes onset and weight gain were assessed, as well as measures of glucose tolerance, lipids and islet morphology.

RESULTS

Liraglutide treatment significantly reduced food intake and body weight and improved glucose tolerance and insulin sensitivity, relative to controls. After 4.5 months, none of the liraglutide-treated rats had developed T2DM (overall p = .019). Liraglutide-treated rats also displayed lower fasting triglyceride (TG) concentrations and lower hepatic TG content, compared to control rats. Islet morphology was improved in liraglutide-treated rats, with significantly increased pancreatic insulin content (p < .05 vs. controls). Although GH treatment tended to increase body weight (and gastrocnemius muscle weight), there were no obvious effects on diabetes onset or other diabetes-related outcomes.

CONCLUSION

GH supplementation did not augment the anti-diabetic effects of liraglutide.

Remnant cholesterol for the detection of glucose metabolic states in patients with coronary heart disease angina pectoris

BACKGROUND

This study aimed to evaluate the relationship between remnant cholesterol (RC) and glucose metabolic states in coronary heart disease (CHD) patients with angina pectoris.

METHODS

This study collected data from 11,557 CHD patients with angina pectoris aged 35-75 years in Tianjin, China. Participants were divided into normal glucose regulation (NGR), prediabetes (Pre-DM) and diabetes mellitus (DM) groups according to glucose metabolic states. Linear regression analysis was used to explore the relationship between glucose metabolism [fasting blood glucose (FBG) and glycated hemoglobin (HbA1c)] and RC levels. Logistic regression was performed to analyze the relationship between RC levels and glucose metabolic states.

RESULTS

Among all participants, 5883 (50.9%) had a DM state and 4034 (34.9%) had a Pre-DM state. FBG levels and HbA1c levels were positively related with RC in all patients (P < 0.001). NGR was used as a reference, multi-adjusted model showing that RC level was significantly associated with Pre-DM [Odds ratio (OR): 1.37; 95% confidence interval (CI) 1.19-1.56; P < 0.001] and DM state (OR:1.47; 95% CI 1.29-1.67; P < 0.001). When considering RC as categorical variables (tertiles), using T1 as a reference, T3 had the strongest relationship between RC levels and Pre-DM and DM state in univariate model and multivariate model. In the stratified analyses, the association between RC levels and pre-DM and DM in women was higher than that in men, and the elderly patients was higher than in the middle-aged patients.

CONCLUSION

The study demonstrated a significant association between RC levels and pre-DM and DM state among CHD patients with angina pectoris, and the relationship was stronger in women and elderly patients.

Caffeic Acid Phenethyl Ester Inhibits Basal Lipolysis by Activating PPAR-Gamma and Increasing Lipid Droplet-Associated Perilipin in Mature Rat Adipocytes

Abnormal lipolysis is correlated with metabolic syndrome. Caffeic acid phenethyl ester (CAPE), a natural product from honeybee hives, has been reported to improve metabolic syndrome. However, the effects of CAPE on lipolysis and perilipin-1 (the major lipid droplet-associated protein) in mature adipocytes were not clarified. In this study, mature adipocytes were isolated from the epididymal fat pads of male rats and incubated with CAPE to estimate lipolysis by measuring glycerol release. It was found that the basal lipolysis was inhibited by CAPE in a dose- and time-dependent manner. The lipid droplet-associated perilipin-1 and phosphorylated peroxisome proliferator-activated receptor (PPAR) gamma levels increased following CAPE treatment by Western blot analysis. Moreover, a specific PPAR-gamma inhibitor (T0070907) could partly reverse the effect of CAPE on basal lipolysis. Furthermore, treatment of adipocytes with dibutyryl-cAMP (db-cAMP) or isoproterenol (ISO) increased lipolysis, but the drug-induced lipolysis was abrogated by combination treatment with CAPE. The lipid droplet-associated perilipin-1 level was also decreased in the drug-induced groups but increased when combined treatment with CAPE. In conclusion, our results revealed that a decrease in basal lipolysis and an increase in lipid droplet-associated perilipin-1 levels induced by CAPE may be involved in the regulation of lipid metabolism through activation of PPAR-gamma in mature adipocytes.

The Effect of Laminaria japonica on Metabolic Syndrome: A Systematic Review of Its Efficacy and Mechanism of Action

Metabolic syndrome (MetS) is a medical condition characterized by abdominal obesity, insulin resistance, high blood pressure, and hyperlipidemia. An increase in the incidence of MetS provokes an escalation in health care costs and a downturn in quality of life. However, there is currently no cure for MetS, and the absence of immediate treatment for MetS has prompted the development of novel therapies. In accordance with recent studies, the brown seaweed Laminaria japonica (LJP) has anti-inflammatory and antioxidant properties, and so forth. LJP contains bioactive compounds used as food globally, and it has been used as a medicine in East Asian countries. We conducted a systematic review to examine whether LJP could potentially be a useful therapeutic drug for MetS. The following databases were searched from initiation to September 2021: PubMed, Web of Science, EMBASE, and Cochrane Central Register of Controlled Trials Library. Clinical trials and in vivo studies evaluating the effects of LJP on MetS were included. LJP reduces the oxidative stress-related lipid mechanisms, inflammatory cytokines and macrophage-related chemokines, muscle cell proliferation, and migration. Bioactive-glucosidase inhibitors reduce diabetic complications, a therapeutic target in obesity and type 2 diabetes. In obesity, LJP increases AMP-activated protein kinase and decreases acetyl-CoA carboxylase. Based on our findings, we suggest that LJP could treat MetS, as it has pharmacological effects on MetS.

Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes

The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.

Destabilization of β Cell FIT2 by saturated fatty acids alter lipid droplet numbers and contribute to ER stress and diabetes

SignificanceWith obesity on the rise, there is a growing appreciation for intracellular lipid droplet (LD) regulation. Here, we show how saturated fatty acids (SFAs) reduce fat storage-inducing transmembrane protein 2 (FIT2)-facilitated, pancreatic β cell LD biogenesis, which in turn induces β cell dysfunction and death, leading to diabetes. This mechanism involves direct acylation of FIT2 cysteine residues, which then marks the FIT2 protein for endoplasmic reticulum (ER)-associated degradation. Loss of β cell FIT2 and LDs reduces insulin secretion, increases intracellular ceramides, stimulates ER stress, and exacerbates diet-induced diabetes in mice. While palmitate and stearate degrade FIT2, unsaturated fatty acids such as palmitoleate and oleate do not, results of which extend to nutrition and diabetes.

Metabolic Syndrome: Updates on Pathophysiology and Management in 2021

Metabolic syndrome (MetS) forms a cluster of metabolic dysregulations including insulin resistance, atherogenic dyslipidemia, central obesity, and hypertension. The pathogenesis of MetS encompasses multiple genetic and acquired entities that fall under the umbrella of insulin resistance and chronic low-grade inflammation. If left untreated, MetS is significantly associated with an increased risk of developing diabetes and cardiovascular diseases (CVDs). Given that CVDs constitute by far the leading cause of morbidity and mortality worldwide, it has become essential to investigate the role played by MetS in this context to reduce the heavy burden of the disease. As such, and while MetS relatively constitutes a novel clinical entity, the extent of research about the disease has been exponentially growing in the past few decades. However, many aspects of this clinical entity are still not completely understood, and many questions remain unanswered to date. In this review, we provide a historical background and highlight the epidemiology of MetS. We also discuss the current and latest knowledge about the histopathology and pathophysiology of the disease. Finally, we summarize the most recent updates about the management and the prevention of this clinical syndrome.

Non-Alcoholic Fatty Liver Disease in HIV/HBV Patients - a Metabolic Imbalance Aggravated by Antiretroviral Therapy and Perpetuated by the Hepatokine/Adipokine Axis Breakdown

Non-alcoholic fatty liver disease (NAFLD) is strongly associated with the metabolic syndrome and is one of the most prevalent comorbidities in HIV and HBV infected patients. HIV plays an early and direct role in the development of metabolic syndrome by disrupting the mechanism of adipogenesis and synthesis of adipokines. Adipokines, molecules that regulate the lipid metabolism, also contribute to the progression of NAFLD either directly or via hepatic organokines (hepatokines). Most hepatokines play a direct role in lipid homeostasis and liver inflammation but their role in the evolution of NAFLD is not well defined. The role of HBV in the pathogenesis of NAFLD is controversial. HBV has been previously associated with a decreased level of triglycerides and with a protective role against the development of steatosis and metabolic syndrome. At the same time HBV displays a high fibrogenetic and oncogenetic potential. In the HIV/HBV co-infection, the metabolic changes are initiated by mitochondrial dysfunction as well as by the fatty overload of the liver, two interconnected mechanisms. The evolution of NAFLD is further perpetuated by the inflammatory response to these viral agents and by the variable toxicity of the antiretroviral therapy. The current article discusses the pathogenic changes and the contribution of the hepatokine/adipokine axis in the development of NAFLD as well as the implications of HIV and HBV infection in the breakdown of the hepatokine/adipokine axis and NAFLD progression.

High-dose Vitamin D Supplementation on Type 1 Diabetes Mellitus Patients: Is there an Improvement in Glycemic Control?

BACKGROUND

Some authors evaluated the effect of VD on hyperglycemia in T1DM, but the results remain controversial. This study aims to analyze the effects of high-dose VD supplementation on T1DM patients' glycemic levels, maintaining stable doses of insulin.

METHODS

Prospective, 12-week clinical trial including 67 T1DM patients, supplemented with high doses of cholecalciferol according to participants' VD value. Patients with VD levels below 30 ng/mL received 10,000 IU/day; those with levels between 30-60 ng/mL received 4,000 IU/day. Patients who had not achieved 25(OH)D levels > 30 ng/ml or presented insulin dose variation during the study were not analyzed.

RESULTS

Only 46 out of 67 patients accomplished the criteria at the end of the study. There was no general improvement in the glycemic control evaluated by HbA1c (9.4 ± 2.4 vs 9.4 ± 2.6, p=NS) after VD supplementation. However, a post-hoc analysis, based on HbA1c variation, identified patients who had HbA1c reduced at least 0.6% (group 1, N = 13 (28%)). In addition, a correlation between 25(OH)D levels with HbA1c and total insulin dose at the end of the study was observed (r = -0.3, p<0.05; r=-0.4, p<0.05, respectively), and a regression model demonstrated that 25(OH)D was independent of BMI, duration of T1DM and final total insulin dose, being capable of determining 9.2% of HbA1c final levels (Unstandardized B coefficient = -0.033 (CI 95%: -0.064 to -0.002), r2 = 0.1, p <0.05).

CONCLUSION

Our data suggest that VD is not widely recommended for glycemic control. Nevertheless, specific patients might benefit from this approach.

Saikosaponin A and D Inhibit Adipogenesis via the AMPK and MAPK Signaling Pathways in 3T3-L1 Adipocytes

Obesity is a lipid metabolism disorder caused by genetic, medicinal, nutritional, and other environmental factors. It is characterized by a complex condition of excess lipid accumulation in adipocytes. Adipogenesis is a differentiation process that converts preadipocytes into mature adipocytes and contributes to excessive fat deposition. Saikosaponin A (SSA) and saikosaponin D (SSD) are triterpenoid saponins separated from the root of the Bupleurum chinensis, which has long been used to treat inflammation, fever, and liver diseases. However, the effects of these constituents on lipid accumulation and obesity are poorly understood. We investigated the anti-obesity effects of SSA and SSD in mouse 3T3-L1 adipocytes. The MTT assay was performed to measure cell viability, and Oil Red O staining was conducted to determine lipid accumulation. Various adipogenic transcription factors were evaluated at the protein and mRNA levels by Western blot assay and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Here, we showed that SSA and SSD significantly inhibited lipid accumulation without affecting cell viability within the range of the tested concentrations (0.938–15 µM). SSA and SSD also dose-dependently suppressed the expression of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), sterol regulatory element binding protein-1c (SREBP-1c), and adiponectin. Furthermore, the decrease of these transcriptional factors resulted in the repressed expression of several lipogenic genes including fatty acid binding protein (FABP4), fatty acid synthase (FAS), and lipoprotein lipase (LPL). In addition, SSA and SSD enhanced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylase (ACC), and inhibited the phosphorylation of extracellular-regulated kinase 1/2 (ERK1/2) and p38, but not c-Jun-N-terminal kinase (JNK). These results suggest that SSA and SSD inhibit adipogenesis through the AMPK or mitogen-activated protein kinase (MAPK) pathways in the early stages of adipocyte differentiation. This is the first study on the anti-adipogenic effects of SSA and SSD, and further research in animals and humans is necessary to confirm the potential of saikosaponins as therapeutic agents for obesity.

Novel role of xanthine oxidase-dependent H2O2 production in 12/15-lipoxygenase-mediated de novo lipogenesis, triglyceride biosynthesis and weight gain

12/15-lipoxygenase (12/15-LOX) plays an essential role in oxidative conversion of polyunsaturated fatty acids into various bioactive lipid molecules. Although 12/15-LOX's role in the pathophysiology of various human diseases has been well studied, its role in weight gain is controversial and poorly clarified. Here, we demonstrated the role of 12/15-LOX in high-fat diet (HFD)-induced weight gain in a mouse model. We found that 12/15-LOX mediates HFD-induced de novo lipogenesis (DNL), triglyceride (TG) biosynthesis and the transport of TGs from the liver to adipose tissue leading to white adipose tissue (WAT) expansion and weight gain via xanthine oxidase (XO)-dependent production of H₂O₂. 12/15-LOX deficiency leads to cullin2-mediated ubiquitination and degradation of XO, thereby suppressing H₂O₂ production, DNL and TG biosynthesis resulting in reduced WAT expansion and weight gain. These findings infer that manipulation of 12/15-LOX metabolism may manifest a potential therapeutic target for weight gain and obesity.

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12/15-LOX-12(S)-HETE axis via activation of CREB-Egr1 enhances TG biosynthesis.

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12/15-LOX-12(S)-HETE axis via activation of SREBP1c triggers DNL.

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H₂O₂ mediates 12/15-LOX-12(S)-HETE axis-induced DNL and TG biosynthesis.

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12/15-LOX via TG biosynthesis leads to WAT expansion and body weight gain.

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Downstream to 12/15-LOX, H₂O₂-mediates WAT expansion and body weight gain.

Serum- and glucocorticoid-induced kinase drives hepatic insulin resistance by directly inhibiting AMP-activated protein kinase

A hallmark of type 2 diabetes (T2D) is hepatic resistance to insulin's glucose-lowering effects. The serum- and glucocorticoid-regulated family of protein kinases (SGK) is activated downstream of mechanistic target of rapamycin complex 2 (mTORC2) in response to insulin in parallel to AKT. Surprisingly, despite an identical substrate recognition motif to AKT, which drives insulin sensitivity, pathological accumulation of SGK1 drives insulin resistance. Liver-specific Sgk1-knockout (Sgk1Lko) mice display improved glucose tolerance and insulin sensitivity and are protected from hepatic steatosis when fed a high-fat diet. Sgk1 promotes insulin resistance by inactivating AMP-activated protein kinase (AMPK) via phosphorylation on inhibitory site AMPKαSer485/491. We demonstrate that SGK1 is dominant among SGK family kinases in regulation of insulin sensitivity, as Sgk1, Sgk2, and Sgk3 triple-knockout mice have similar increases in hepatic insulin sensitivity. In aggregate, these data suggest that targeting hepatic SGK1 may have therapeutic potential in T2D.

A plant-based meal reduces postprandial oxidative and dicarbonyl stress in men with diabetes or obesity compared with an energy- and macronutrient-matched conventional meal in a randomized crossover study

BACKGROUND

Increased oxidative/dicarbonyl stress and chronic inflammation are considered key pathophysiological mediators in the progression of complications in obesity and type 2 diabetes (T2D). Lifestyle and diet composition have a major impact. In this study, we tested the effects of a vegan (V) and a conventional meat containg (M) meal, matched for energy and macronutrients, on postprandial oxidative and dicarbonyl stress, inflammatory markers and appetite hormones.

METHODS

A randomised crossover design was used to evaluate T2D, obese with normal glucose tolerance and control participants (n = 20 in each group), with serum concentrations of analytes determined at 0, 120 and 180 min. Repeated-measures ANOVA was used for statistical analysis.

RESULTS

In T2D subjects, we observed decreased postprandial concentrations of oxidised glutathione (p ˂ 0.001) and increased glutathione peroxidase activity (p = 0.045) after the V-meal consumption, compared with the M-meal. In obese participants, V-meal consumption increased postprandial concentrations of reduced glutathione (p = 0.041) and decreased methylglyoxal concentrations (p = 0.023). There were no differences in postprandial secretion of TNFα, MCP-1 or ghrelin in T2D or obese men, but we did observe higher postprandial secretion of leptin after the V-meal in T2D men (p = 0.002) compared with the M-meal.

CONCLUSIONS

The results show that a plant-based meal is efficient in ameliorating the postprandial oxidative and dicarbonyl stress compared to a conventional energy- and macronutrient-matched meal, indicating the therapeutic potential of plant-based nutrition in improving the progression of complications in T2D and obese patients. Registered under ClinicalTrials.gov Identifier No. NCT02474147.

Effect of starch-hydrocolloid complexes with heat-moisture treatment on in vivo digestibility

The purpose of this study was to investigate the effect of starch-hydrocolloid (gum arabic, xanthan gum, and guar gum) complexes with heat-moisture treatment (HMT) on in vivo digestibility. In vivo digestibility experiments revealed that the body weight, liver weight, and fat index of mice in the intervention group were significantly reduced compared with those in the high-fat group. Glucose tolerance improved, and blood lipid levels, liver and adipose tissue morphology returned to normal. The results of mRNA expression levels showed that the intervention of corn starch-hydrocolloid complexes after HMT down-regulated the expression level of genes related to fat synthesis compared with the high-fat group, which could decrease lipid deposition and stabilize blood lipid levels. Results revealed that starch-xanthan gum complex (1 : 40 ratio) with HMT could markedly reduce the digestibility of starch. Overall, this study provides new ideas for the application of low-glycemic-index and functional foods.

Association of hypertriglyceridemic waist-to-height ratio and its dynamic status with risk of type 2 diabetes mellitus: The Rural Chinese Cohort Study

AIMS

To evaluate the risk of type 2 diabetes mellitus (T2DM) in a prospective study with hypertriglyceridemic waist-to-height ratio (HWHtR) and its dynamic status.

METHODS

We collected data for 12,248 participants ≥18 years in this study. Cox's proportional-hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for T2DM risk by baseline HWHtR. Multiple logistic regression analysis was used to estimate odds ratios (ORs) and 95% CIs for T2DM risk by transformation in HWHtR.

RESULTS

We identified 839 T2DM cases during a median follow-up of 5.92 years. Compared with normal TG level and normal WHtR, T2DM risk was increased with high TG level and high WHtR (aHR 2.04, 95% CI 1.49-2.79). Similar results were observed in subgroup analyses by sex and age. During follow-up, T2DM risk was increased with stable high TG level and high WHtR (aOR 4.45, 95% CI 2.76-7.17) compared with stable normal TG level and normal WHtR. The results above were robust in sensitivity analyses.

CONCLUSIONS

HWHtR phenotype and its dynamic status were associated with risk of T2DM. Our study suggests that primary prevention and avoiding the appearance of the HWHtR phenotype in the rural Chinese population may reduce the T2DM risk.

PEGylated AdipoRon derivatives improve glucose and lipid metabolism under insulinopenic and high-fat diet conditions

The pleiotropic actions of adiponectin in improving cell survival and metabolism have motivated the development of small-molecule therapeutic agents for treating diabetes and lipotoxicity. AdipoRon is a synthetic agonist of the adiponectin receptors, yet is limited by its poor solubility and bioavailability. In this work, we expand on the protective effects of AdipoRon in pancreatic β-cells and examine how structural modifications could affect the activity, pharmacokinetics, and bioavailability of this small molecule. We describe a series of AdipoRon analogs containing amphiphilic ethylene glycol (PEG) chains. Among these, AdipoRonPEG5 induced pleiotropic effects in mice under insulinopenic and high-fat diet (HFD) conditions. While both AdipoRon and AdipoRonPEG5 substantially attenuate palmitate-induced lipotoxicity in INS-1 cells, only AdipoRonPEG5 treatment is accompanied by a significant reduction in cytotoxic ceramides. In vivo, AdipoRonPEG5 can substantially reduce pancreatic, hepatic, and serum ceramide species, with a concomitant increase in the corresponding sphingoid bases and improves insulin sensitivity of mice under HFD feeding conditions. Furthermore, hyperglycemia in streptozotocin (STZ)-induced insulinopenic adiponectin-null mice is also attenuated upon AdipoRonPEG5 treatment. Our results suggest that AdipoRonPEG5 is more effective in reducing ceramides and dihydroceramides in the liver of HFD-fed mice than AdipoRon, consistent with its potent activity in activating ceramidase in vitro in INS-1 cells. Additionally, these results indicate that the beneficial effects of AdipoRonPEG5 can be partially attributed to improved pharmacokinetics as compared with AdipoRon, thus suggesting that further derivatization may improve affinity and tissue-specific targeting.

NADPH Oxidase (NOX) Targeting in Diabetes: A Special Emphasis on Pancreatic β-Cell Dysfunction

In type 2 diabetes, metabolic stress has a negative impact on pancreatic β-cell function and survival (T2D). Although the pathogenesis of metabolic stress is complex, an imbalance in redox homeostasis causes abnormal tissue damage and β-cell death due to low endogenous antioxidant expression levels in β-cells. Under diabetogenic conditions, the susceptibility of β-cells to oxidative damage by NADPH oxidase has been related to contributing to β-cell dysfunction. Here, we consider recent insights into how the redox response becomes deregulated under diabetic conditions by NADPH oxidase, as well as the therapeutic benefits of NOX inhibitors, which may provide clues for understanding the pathomechanisms and developing strategies aimed at the treatment or prevention of metabolic stress associated with β-cell failure.

Low expression of miR-19a-5p is associated with high mRNA expression of diacylglycerol O-acyltransferase 2 (DGAT2) in hybrid tilapia

DGAT2 (acyl CoA:diacylglycerol acyltransferase 2) is a key and rate-limiting enzyme that catalyzes the final step of triglyceride (TG) synthesis. In this study, hybrid tilapia were generated from Nile tilapia (♀) and blue tilapia (♂) crossing. The TG content levels in the liver of these tilapia were measured. The results showed that the TG content was higher in the hybrid tilapia. In addition, protein and mRNA expression levels in the tilapia livers were determined. Higher hepatic mRNA and protein expression of DGAT2 in the hybrid fish was found. A luciferase reporter assay with HEK293T cells revealed that miRNA-19a-5p targeted the 3'UTR of DGAT2, suggesting a direct regulatory mechanism. Using qRT-PCR, we found that DGAT2 mRNA levels had a negative correlation with miRNA-19a-5p expression in Nile tilapia and hybrid. Taken together, these findings provide evidence that miRNA-19a-5p is involved in TG synthesis in the regulation of lipid metabolism in tilapia.

FIT2 is an acyl-coenzyme A diphosphatase crucial for endoplasmic reticulum homeostasis

The endoplasmic reticulum is a cellular hub of lipid metabolism, coordinating lipid synthesis with continuous changes in metabolic flux. Maintaining ER lipid homeostasis despite these fluctuations is crucial to cell function and viability. Here, we identify a novel mechanism that is crucial for normal ER lipid metabolism and protects the ER from dysfunction. We identify the molecular function of the evolutionarily conserved ER protein FIT2 as a fatty acyl–coenzyme A (CoA) diphosphatase that hydrolyzes fatty acyl–CoA to yield acyl 4′-phosphopantetheine. This activity of FIT2, which is predicted to be active in the ER lumen, is required in yeast and mammalian cells for maintaining ER structure, protecting against ER stress, and enabling normal lipid storage in lipid droplets. Our findings thus solve the long-standing mystery of the molecular function of FIT2 and highlight the maintenance of optimal fatty acyl–CoA levels as key to ER homeostasis.

Peroxisomes and pancreatic beta-cell lipo-dysfunction

AIMS

Pancreatic beta-cell lipo-dysfunction decreases insulin secretion and predisposes to the development of type 2 diabetes. Through targeted Pex11β knockdown and peroxisome depletion, our aim was to investigate the specific contribution of peroxisomes to palmitate mediated pancreatic beta-cell dysfunction.

METHODS

MIN6 cells were transfected with probes targeted against Pex11β, a regulator of peroxisome abundance, or with scrambled control probes. Peroxisome abundance was measured by PMP-70 protein expression. 48 h post transfection, cells were incubated with 250 μM palmitate or BSA control for a further 48 h before measurement of glucose stimulated insulin secretion and of reactive oxygen species.

RESULTS

Pex11β knockdown decreased target gene expression by >80% compared with the scrambled control (P<0.001). This led to decreased PMP-70 expression (p<0.01) and a 22% decrease in peroxisome number (p<0.05). At 25 mM glucose, palmitate treatment decreased insulin secretion by 64% in the scrambled control cells (2.54±0.25 vs 7.07±0.83 [mean±SEM] ng/h/μg protein; Palmitate vs BSA P<0.001), but by just 37% in the Pex11β knockdown cells. Comparing responses in the presence of palmitate, insulin secretion at 25 mM glucose was significantly greater in the Pex11β knockdown cells compared with the scrambled controls (4.04±0.46 vs 2.54±0.25 ng/h/μg protein; p<0.05). Reactive oxygen species generation with palmitate was lower in the Pex11β knockdown cells compared with the scrambled controls (P<0.001).

CONCLUSION

Pex11β knockdown decreased peroxisome abundance, decreased palmitate mediated reactive oxygen species generation, and reversed the inhibitory effect of palmitate on insulin secretion. These findings reveal a distinct role of peroxisomes in palmitate mediated beta-cell dysfunction.

Increased particle size of triacylglycerol-enriched remnant lipoproteins, but not their plasma concentration or lipid content, augments risk prediction of incident type 2 diabetes

AIMS/HYPOTHESIS

Type 2 diabetes prevention requires the accurate identification of those at high risk. Beyond the association of fasting serum triacylglycerols with diabetes, triacylglycerol-enriched remnant lipoproteins (TRLs) more accurately reflect pathophysiological changes that underlie progression to diabetes, such as hepatic insulin resistance, pancreatic steatosis and systemic inflammation. We hypothesised that TRL-related factors could improve risk prediction for incident diabetes.

METHODS

We included individuals from the Brazilian Longitudinal Study of Adult Health cohort. We trained a logistic regression model for the risk of incident diabetes in 80% of the cohort using tenfold cross-validation, and tested the model in the remaining 20% of the cohort (test set). Variables included medical history and traits of the metabolic syndrome, followed by TRL-related measurements (plasma concentration, TRL particle diameter, cholesterol and triacylglycerol content). TRL features were measured using NMR spectroscopy. Discrimination was assessed using the area under the receiver operating characteristic curve (AUROC) and the area under the precision-recall curve (AUPRC).

RESULTS

Among 4463 at-risk individuals, there were 366 new cases of diabetes after a mean (±SD) of 3.7 (±0.63) years of follow-up. We derived an 18-variable model with a global AUROC of 0.846 (95% CI: 0.829, 0.869). Overall TRL-related markers were not associated with diabetes. However, TRL particle diameter increased the AUROC, particularly in individuals with HbA_1c <39 mmol/mol (5.7%) (hold-out test set [n = 659]; training-validation set [n = 2638]), but not in individuals with baseline HbA_1c 39-46 mmol/mol (5.7-6.4%) (hold-out test set [n = 233]; training-validation set [n = 933]). In the subgroup with baseline HbA_1c <39 mmol/mol (5.7%), AUROC in the test set increased from 0.717 (95% CI 0.603, 0.818) to 0.794 (95% CI 0.731, 0.862), and AUPRC in the test set rose from 0.582 to 0.701 when using the baseline model and the baseline model plus TRL particle diameter, respectively. TRL particle diameter was highly correlated with obesity, insulin resistance and inflammation in those with impaired fasting glucose at baseline, but less so in those with HbA_1c <39 mmol/mol (5.7%).

CONCLUSIONS/INTERPRETATION

TRL particle diameter improves the prediction of diabetes, but only in individuals with HbA_1c <39 mmol/mol (5.7%) at baseline. These data support TRL particle diameter as a risk factor that is changed early in the course of the pathophysiological processes that lead to the development of type 2 diabetes, even before glucose abnormalities are established. Graphical abstract.

Adipocyte lipolysis: from molecular mechanisms of regulation to disease and therapeutics

Fatty acids (FAs) are stored safely in the form of triacylglycerol (TAG) in lipid droplet (LD) organelles by professional storage cells called adipocytes. These lipids are mobilized during adipocyte lipolysis, the fundamental process of hydrolyzing TAG to FAs for internal or systemic energy use. Our understanding of adipocyte lipolysis has greatly increased over the past 50 years from a basic enzymatic process to a dynamic regulatory one, involving the assembly and disassembly of protein complexes on the surface of LDs. These dynamic interactions are regulated by hormonal signals such as catecholamines and insulin which have opposing effects on lipolysis. Upon stimulation, patatin-like phospholipase domain containing 2 (PNPLA2)/adipocyte triglyceride lipase (ATGL), the rate limiting enzyme for TAG hydrolysis, is activated by the interaction with its co-activator, alpha/beta hydrolase domain-containing protein 5 (ABHD5), which is normally bound to perilipin 1 (PLIN1). Recently identified negative regulators of lipolysis include G0/G1 switch gene 2 (G0S2) and PNPLA3 which interact with PNPLA2 and ABHD5, respectively. This review focuses on the dynamic protein-protein interactions involved in lipolysis and discusses some of the emerging concepts in the control of lipolysis that include allosteric regulation and protein turnover. Furthermore, recent research demonstrates that many of the proteins involved in adipocyte lipolysis are multifunctional enzymes and that lipolysis can mediate homeostatic metabolic signals at both the cellular and whole-body level to promote inter-organ communication. Finally, adipocyte lipolysis is involved in various diseases such as cancer, type 2 diabetes and fatty liver disease, and targeting adipocyte lipolysis is of therapeutic interest.

Association of TG/HDLC ratio trajectory and risk of type 2 diabetes: A retrospective cohort study in China

BACKGROUND

The association of ratio of triglycerides to high-density lipoprotein cholesterol (TG/HDL-C ratio) change trajectory with risk of type 2 diabetes mellitus (T2DM) remains unknown. The aim of this study was to evaluate the association between risk of T2DM and TG/HDL-C ratio change trajectory.

METHODS

A total of 18 444 participants aged 18-80 years old were included in this cohort study. Linear regression and quadratic regression models were used to determine the TG/HDL-C ratio change trajectory. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between TG/HDL-C ratio change trajectory and probability of T2DM.

RESULTS

T2DM developed in 714 participants during a median follow-up of 5.74 years (92 076.23 person-years of follow-up). After adjusting for baseline potential confounders, odds of T2DM were greater for participants with the increasing, U-shape, bell-shape, and other shape change vs decreasing change (adjusted OR [aOR] 2.01, 95% CI 1.42-2.81; 1.56, 1.15-2.13; 1.60, 1.17-2.20; and 1.49, 1.13-2.00, respectively). The results were robust in the sensitivity analyses on excluding baseline participants with T2DM. Moreover, the associations remained significant with male sex, age <60 years and body mass index <24 kg/m2 .

CONCLUSIONS

This retrospective study revealed increased probability of T2DM with increasing, U-shape, bell-shape, and other-shape TG/HDL-C ratio change trajectories, especially with male sex, age <60 years and body mass index <24 kg/m2 .

FATP2-targeted therapies - A role beyond fatty liver disease

Fatty acid transport protein 2 (FATP2) is a multifunctional protein whose specific function is determined by the type of located cell, its intracellular location, or organelle-specific interactions. In the different diseases setting, a newfound appreciation for the biological function of FATP2 has come into view. Two main functions of FATP2 are to activate long-chain fatty acids (LCFAs) as a very long-chain acyl-coenzyme A (CoA) synthetase (ACSVL) and to transport LCFAs as a fatty acid transporter. FATP2 is not only involved in the occurrence of nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM), but also plays an important role in lithogenic diet-induced cholelithiasis, the formation of cancer tumor immunity, the progression of chronic kidney disease (CKD), and the regulation of zoledronate-induced nephrotoxicity. Herein, we review the updated information on the role of FATP2 in related diseases. In particular, we discuss the new functions of FATP2 and propose that FATP2 is a potential clinical biomarker and therapeutic target. In conclusion, regulatory strategies for FATP2 may bring new treatment options for cancer and lipid metabolism-related disorders.

Simultaneous evaluation of metabolomic and inflammatory biomarkers in children with different body mass index (BMI) and waist-to-height ratio (WHtR)

Metabolic disturbances and systemic pro-inflammatory changes have been reported in children with obesity. However, it is unclear the time-sequence of metabolic or inflammatory modifications during children obesity evolution. Our study aimed to quantify simultaneously metabolomic and inflammatory biomarkers in serum from children with different levels of adiposity. For this purpose, a cross-sectional study was used to perform targeted metabolomics and inflammatory cytokines measurements. Serum samples from children between six to ten years old were analyzed using either body mass index (BMI) or waist-to-height ratio (WHtR) classifications. One hundred and sixty-eight school-aged children were included. BMI classification in children with overweight or obesity showed altered concentrations of glucose and amino acids (glycine and tyrosine). Children classified by WHtR exhibited imbalances in amino acids (glycine, valine, and tyrosine) and lipids (triacyl glycerides and low-density lipoprotein) compared to control group. No differences in systemic inflammation biomarkers or in the prevalence of other results were found in these children. Abnormal arterial blood pressure was found in 32% of children with increased adiposity. In conclusion, obesity in school-aged children is characterized by significant metabolic modifications that are not accompanied by major disturbances in circulating concentrations of inflammatory biomarkers.

JNK-mediated disruption of bile acid homeostasis promotes intrahepatic cholangiocarcinoma

Metabolic stress causes activation of the cJun NH2-terminal kinase (JNK) signal transduction pathway. It is established that one consequence of JNK activation is the development of insulin resistance and hepatic steatosis through inhibition of the transcription factor PPARα. Indeed, JNK1/2 deficiency in hepatocytes protects against the development of steatosis, suggesting that JNK inhibition represents a possible treatment for this disease. However, the long-term consequences of JNK inhibition have not been evaluated. Here we demonstrate that hepatic JNK controls bile acid production. We found that hepatic JNK deficiency alters cholesterol metabolism and bile acid synthesis, conjugation, and transport, resulting in cholestasis, increased cholangiocyte proliferation, and intrahepatic cholangiocarcinoma. Gene ablation studies confirmed that PPARα mediated these effects of JNK in hepatocytes. This analysis highlights potential consequences of long-term use of JNK inhibitors for the treatment of metabolic syndrome.

Constituents from Solidago virgaurea var. gigantea and their inhibitory effect on lipid accumulation

In this study, the anti-adipogenic activities of compounds isolated from Solidago viraurea var. gigantea (SG) extracts were investigated using Oil Red O staining in the 3T3-L1 cell line. Four known compounds including 3,5-di-O-caffeoylquinic acid (5), protocatechuic acid (6), chlorogenic acid (7), and kaempferol-3-O-rutinoside (8), and four undescribed compounds including (1R,2S,3S,5R,7S)-methyl 7-((cinnamoyloxy)methyl)-2,3-dihydroxy-6,8-dioxabicyclo[3.2.1]octane-5-carboxylate (1), (1R,2S,3S,5R,7S)-methyl 2,3-dihydroxy-7-((((Z)-3-phenylacryloyl)oxy)methyl)-6,8-dioxabicyclo[3.2.1]octane-5-carboxylate (2), (1R,2S,3S,5R,7S)-2,3-dihydroxy-7-((((Z)-3-phenylacryloyl)oxy)methyl)-6,8-dioxabicyclo[3.2.1]octane-5-carboxylic acid (3), and (1R,2S,3S,5R,7S)-7-((cinnamoyloxy)methyl)-2,3-dihydroxy-6,8-dioxabicyclo[3.2.1]octane-5-carboxylic acid (4) were isolated from S. viraurea var. gigantea. The structures of the compounds were first identified by comparing their ¹H NMR spectra with spectral data from the literature and a more detailed identification was then performed using 2D NMR (Correlated spectroscopy (COSY), heteronuclear single quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), and nuclear overhauser spectroscopy (NOESY)), and X-ray crystallography analyses. The anti-adipogenic activities of all compounds were evaluated by MTT assay and Oil Red O staining in 3T3-L1 cells. 3,5-di-O-caffeoylquinic acid was found to inhibit lipid accumulation more potently than the other tested compounds.

TXNIP hypomethylation and its interaction with obesity and hypertriglyceridemia increase type 2 diabetes mellitus risk: A nested case-control study

BACKGROUND

This study aims to estimate type 2 diabetes mellitus (T2DM) incidence with DNA methylation of the thioredoxin-interacting protein (TXNIP) gene and its interaction with environmental factors.

MATERIALS AND METHODS

This case-control study included 286 incident T2DM cases and 286 non-T2DM controls matched by sex, age, marital status, race, and residence village nested in the Rural Chinese Cohort Study. A conditional logistic regression model was used to estimate the association of DNA methylation at TXNIP gene with T2DM risk. Also, multifactor dimensionality reduction (MDR) and classification and regression tree (CART) analyses were used to investigate the interaction between TXNIP methylation and environmental risk factors.

RESULTS

Methylation levels of all five CpG loci at TXNIP gene were significantly lower in T2DM than in controls (all P < .001). With increasing methylation level, risk of T2DM was significantly decreased (odds ratio, 95% CI 0.80, 0.69-0.94 for CpG1; 0.80, 0.69-0.93 for CpG2; 0.70, 0.56-0.88 for CpG3; 0.78, 0.66-0.92 for CpG4; and 0.76, 0.60-0.97 for CpG5). Additionally, the essential interactions among TXNIP methylation, obesity, and hypertriglyceridemia were identified by CART and MDR analyses. On logistic regression analysis, the risk of T2DM was reduced with terminal node 5 (CpG3 methylation ≥72%, nonobesity, normal triglyceride (TG) level, and CpG4 methylation ≥83%) vs terminal node 1 (CpG3 methylation <72%) (odds ratio 95% CI 0.20, 0.10-0.40).

CONCLUSIONS

TXNIP methylation is associated with T2DM incidence in a Chinese population. Interaction between TXNIP methylation and environmental factors may influence T2DM risk and needs more investigation.

Triglyceride to HDL-cholesterol ratio and the incidence risk of type 2 diabetes in community dwelling adults: A longitudinal 12-year analysis of the Korean Genome and Epidemiology Study

AIMS

Serum triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio is known to be associated with cardiometabolic diseases. This study is aimed to evaluate the association between the TG/HDL-C ratio and incident type 2 diabetes with a large-sample, community-based Korean cohort over 12 years.

METHODS

Among 10,038 participants, a total of 8655 participants aged 40 to 69 years without diabetes were selected from the Korean Genome and Epidemiology Study (KoGES). The baseline TG/HDL-C ratio was divided into quartiles. Newly developed type 2 diabetes was defined by any of the following: a fasting plasma glucose level ≥ 126 mg/dL; a glucose level ≥ 200 mg/dL 2-hours after a 75 g oral glucose tolerance test; an HbA1c ≥ 6.5%; or treatment with anti-diabetic therapy. The hazard ratios (HRs) with 95% confidence intervals (CIs) for incident type 2 diabetes were calculated using multivariate Cox proportional hazards regression models after adjusting for potentially confounding variables.

RESULTS

During the 12-year follow-up period, type 2 diabetes developed in 1437 subjects (16.6%, 1437/8655), with incidence rate of 2.8-5.0 (over 2 years). Compared to the reference first quartile, the HRs (95% CIs) of incident type 2 diabetes in the second, third, and fourth quartiles increased in a dose-response manner after adjusting for potentially confounding variables.

CONCLUSIONS

High TG/HDL-C ratio at baseline may be a useful surrogate indicator of future incident type 2 diabetes.

The Role of CD36 in Type 2 Diabetes Mellitus: β-Cell Dysfunction and Beyond

Impaired β-cell function is the key pathophysiology of type 2 diabetes mellitus, and chronic exposure of nutrient excess could lead to this tragedy. For preserving β-cell function, it is essential to understand the cause and mechanisms about the progression of β-cells failure. Glucotoxicity, lipotoxicity, and glucolipotoxicity have been suggested to be a major cause of β-cell dysfunction for decades, but not yet fully understood. Fatty acid translocase cluster determinant 36 (CD36), which is part of the free fatty acid (FFA) transporter system, has been identified in several tissues such as muscle, liver, and insulin-producing cells. Several studies have reported that induction of CD36 increases uptake of FFA in several cells, suggesting the functional interplay between glucose and FFA in terms of insulin secretion and oxidative metabolism. However, we do not currently know the regulating mechanism and physiological role of CD36 on glucolipotoxicity in pancreatic β-cells. Also, the downstream and upstream targets of CD36 related signaling have not been defined. In the present review, we will focus on the expression and function of CD36 related signaling in the pancreatic β-cells in response to hyperglycemia and hyperlipidemia (ceramide) along with the clinical studies on the association between CD36 and metabolic disorders.

Modulation of Glucose Metabolism by Leaf Tea Constituents: A Systematic Review of Recent Clinical and Pre-clinical Findings

Leaf teas are widely used as a purported treatment for dysregulated glucose homeostasis. The objective of this study was to systematically evaluate the clinical and cellular-metabolic evidence, published between January 2013 and May 2019, and indexed on PubMed, ScienceDirect, and Web of Science, supporting the use of leaf teas for this purpose. Fourteen randomized controlled trials (RCTs) (13 on Camellia sinensis teas) were included, with mixed results, and providing scant mechanistic information. In contrast, 74 animal and cell culture studies focusing on the pancreas, liver, muscle, and adipose tissue yielded mostly positive results and highlighted enhanced insulin signaling as a recurring target associated with the effects of teas on glucose metabolism. We conclude that more studies, including RCTs and pre-clinical studies examining teas from a wider variety of species beyond C. sinensis, are required to establish a stronger evidence base on the use of leaf teas to normalize glucose metabolism.

A retrospective cohort study of preoperative lipid indices and their impact on new-onset diabetes after liver transplantation

Background

The correlation between preoperative lipid profiles and new‐onset diabetes after transplantation (NODAT) remains relatively unexplored in liver transplant recipients (LTRs). Thus, we aimed to investigate the preoperative lipid profiles in Chinese LTRs and evaluate the different influences of preoperative total cholesterol, total triglycerides (TG), high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol on the development of NODAT in both sexes.

Methods

A total of 767 Chinese LTRs from Zhongshan Hospital were retrospectively evaluated. NODAT was defined according to the American Diabetes Association guidelines; the relationship between each preoperative lipid index and NODAT development was analyzed separately in men and women.

Results

Pretransplant hypotriglyceridemia was observed in 35.72% of the total LTRs. In men, only the preoperative TG level was significantly associated with incident NODAT after adjusting for potential confounders (hazard ratio 1.37, 95% confidence interval 1.13‐1.66, P = .001). There was a nonlinear relationship between the preoperative TG level and NODAT risk. The risk of NODAT significantly increased with preoperative a TG level above 0.54 mmol/L (log‐likelihood ratio test, P = .043). In women, no significant association was observed.

Conclusion

Among male LTRs, a higher preoperative TG level, even at a low level within the normal range, was significantly and nonlinearly associated with an increased risk of NODAT.

mRNA expression of genes related to fat deposition during in vitro ovine adipogenesis

Fat deposition in animals involves adipogenic differentiation guided by transcriptional factors and other key factors. To understand the molecular mechanism underlying ovine adipogenic differentiation, the dynamic mRNA expression of key genes related to fat deposition, including peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid-binding protein 4 (FABP4), FABP5, and cellular retinoic acid-binding protein 2 (CRABP2), were analyzed during in vitro differentiation of ovine preadipocytes. The stromal vascular cells from underneath the tail fat tissue of 1-wk-old sheep were isolated and cultured, and the preadipocytes were induced using a cocktail of 3-isobutyl-1-methylxanthine, insulin, dexamethasone, and troglitazone. The cultivated cells were collected at different time points after induced differentiation. The expression levels of PPAR-γ, FABP4, FABP5, and CRABP2 were studied by quantitative real-time polymerase chain reaction. The expressions of these genes in sheep were compared with those in human and mouse retrieved from the Gene Expression Omnibus DataSets. We observed that the expression of PPAR-γ, FABP4, and FABP5 was increased upon differentiation of ovine preadipocytes, as in humans and mice. The expression of CRABP2 was sharply increased from days 0 to 2 after induced differentiation and was subsequently decreased. This expression pattern of CRABP2 was different from that observed in humans and mice. Our results provide new insights into the function of these genes in fat deposition.

Reassessing the Role of Diacylglycerols in Insulin Resistance

Skeletal muscle (SM) insulin resistance (IR) plays an important role in the burden of obesity, particularly because it leads to glucose intolerance and type 2 diabetes. Among the mechanisms thought to link IR to obesity is the accumulation, in muscle cells, of different lipid metabolites. Diacylglycerols (DAGs) are subject of particular attention due to reported interactions with the insulin signaling cascade. Given that SM accounts for the majority of insulin-stimulated glucose uptake, this review integrates recent observational and mechanistic works with the sole focus on questioning the role of DAGs in SM IR. Particular attention is given to the subcellular distributions and specific structures of DAGs, highlighting future research directions towards reaching a consensus on the mechanistic role played by DAGs.

Lipotoxicity in Kidney, Heart, and Skeletal Muscle Dysfunction

Dyslipidemia is a common nutritional and metabolic disorder in patients with chronic kidney disease. Accumulating evidence supports the hypothesis that prolonged metabolic imbalance of lipids leads to ectopic fat distribution in the peripheral organs (lipotoxicity), including the kidney, heart, and skeletal muscle, which accelerates peripheral inflammation and afflictions. Thus, lipotoxicity may partly explain progression of renal dysfunction and even extrarenal complications, including renal anemia, heart failure, and sarcopenia. Additionally, endoplasmic reticulum stress activated by the unfolded protein response pathway plays a pivotal role in lipotoxicity by modulating the expression of key enzymes in lipid synthesis and oxidation. Here, we review the molecular mechanisms underlying lipid deposition and resultant tissue damage in the kidney, heart, and skeletal muscle, with the goal of illuminating the nutritional aspects of these pathologies.

Ameliorative Effect and Mechanism of the Purified Anthraquinone-Glycoside Preparation from Rheum Palmatum L. on Type 2 Diabetes Mellitus

Rheum palmatum L. is a traditional Chinese medicine with various pharmacological properties, including anti-inflammatory, antibacterial, and detoxification effects. In this study, the mechanism of the hypoglycemic effect of purified anthraquinone-Glycoside from Rheum palmatum L. (PAGR) in streptozotocin (STZ) and high-fat diet induced type 2 diabetes mellitus (T2DM) in rats was investigated. The rats were randomly divided into normal (NC), T2DM, metformin (Met), low, middle (Mid), and high (Hig) does of PAGR groups. After six weeks of continuous administration of PAGR, the serum indices and tissue protein expression were determined, and the pathological changes in liver, kidney, and pancreas tissues were observed. The results showed that compared with the type 2 diabetes mellitus group, the fasting blood glucose (FBG), total cholesterol (TC), and triglyceride (TG) levels in the serum of rats in the PAGR treatment groups were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) levels were noticeably increased. The expression of Fas ligand (FasL), cytochrome C (Cyt-c), and caspase-3 in pancreatic tissue was obviously decreased, and the pathological damage to the liver, kidney, and pancreas was improved. These indicate that PAGR can reduce oxidative stress in rats with diabetes mellitus by improving blood lipid metabolism and enhancing their antioxidant capacity, thereby regulating the mitochondrial apoptotic pathway to inhibitβ-cell apoptosis and improve β-cell function. Furthermore, it can regulate Fas/FasL-mediated apoptosis signaling pathway to inhibit β-cell apoptosis, thereby lowering blood glucose levels and improving T2DM.