CD36 gene variants is associated with type 2 diabetes mellitus through the interaction of obesity in rural Chinese adults

Activation of SIRT3 by Tanshinone IIA ameliorates renal fibrosis by suppressing the TGF-β/TSP-1 pathway and attenuating oxidative stress

Although doxorubicin (DOX) is a common chemotherapeutic drug, the serious nephrotoxicity caused by DOX-induced renal fibrosis remains a considerable clinical problem. Tanshinone IIA (Tan IIA), a compound extracted from Salvia miltiorrhiza, has been reported to have an anti-fibrotic effect. Therefore, this study investigated the molecular pathway whereby Tan IIA protects the kidneys from DOX administration. DOX (3 mg/kg body weight) was intraperitoneally administered every 3 d for a total of 7 injections (cumulative dose of 21 mg/kg) to induce nephrotoxicity. Then, Tan IIA (5 or 10 mg/kg/d) was administered by intraperitoneal injection for 28 d. In an in vitro study, 293 T cells were cultured and treated with DOX and Tan IIA for 24 h. Tan IIA reduced the blood urea nitrogen levels elevated by DOX while increasing superoxide dismutase activity, down-regulating reactive oxygen species, ameliorating renal-tubule thickening, and rescuing mitochondrial morphology. Additionally, Tan IIA reduced the renal collagen deposition, increased ATP production and complex-I activity, down-regulated transforming growth factor-β1 (TGF-β1) and thrombospondin-1 (TSP-1), and up-regulated sirtuin 3 (SIRT3). Tan IIA significantly increased cell viability. Additionally, RNA interference was employed to silence the expression of SIRT3, which eliminated the effect of Tan IIA in suppressing the expression of TGF-β1 and TSP-1. In conclusion, Tan IIA ameliorated DOX-induced nephrotoxicity by attenuating oxidative injury and fibrosis. The Tan IIA-induced rescue of mitochondrial morphology and function while alleviating renal fibrosis may be associated with the activation of SIRT3 to suppress the TGF-β/TSP-1 pathway.

Associations of Lifestyle and Genetic Risks with Obesity and Related Chronic Diseases in the UK Biobank: A Prospective Cohort Study

BACKGROUND

Interplay between lifestyle risk scores (LRSs) and genetic risk scores (GRSs) on obesity and related chronic diseases are underinvestigated and necessary for understanding obesity causes and developing prevention strategies.

OBJECTIVES

This study aimed to investigate independent and joint associations and interactions of LRS and GRS with obesity prevalence and risks of diabetes, cardiovascular disease (CVD), and obesity-related cancer.

METHODS

In this cohort study of 444,957 UK Biobank participants [age: 56.5 ± 8.1 y; BMI (in kg/m2): 27.4 ± 4.7], LRS included physical activity, dietary score, sedentary behavior, sleep duration, and smoking (range: 0-20, each factor had 5 levels). GRS was calculated based on 941 genetic variants related to BMI. Both scores were categorized into quintiles. Obesity (n = 106,301) was defined as baseline BMI ≥30. Incident diabetes (n = 16,311), CVD (n = 18,076), and obesity-related cancer (n = 17,325) were ascertained through linkage to registries over a median of 12-y follow-up.

RESULTS

The LRS and GRS were independently positively associated with all outcomes. Additive interactions of LRS and GRS were observed for all outcomes (P < 0.021). Comparing the top with bottom LRS quintile, prevalence differences (95% CIs) for obesity were 17.8% (15.9%, 19.7%) in the top GRS quintile and 10.7% (8.3%, 13.1%) in the bottom GRS quintile; for diabetes, CVD, and obesity-related cancer, incidence rate differences associated with per SD increase in LRS were greater in the top than that in the bottom GRS quintile. Participants from top quintiles of both LRS and GRS had 6.16-fold, 3.81-fold, 1.56-fold, and 1.44-fold higher odds/risks of obesity, diabetes, CVD, and obesity-related cancer, respectively, than those from bottom quintiles of both scores.

CONCLUSIONS

Higher LRS was associated with higher obesity prevalence and risks of related chronic diseases regardless of GRS, highlighting the broad benefits of healthy lifestyles. Additive gene-lifestyle interactions emphasize the public health importance of lifestyle interventions among people with high genetic risks.

Association of cluster determinant 36, scavenger receptor class B type 1, and major facilitator superfamily domain containing the 2a genetic polymorphism with serum lipid profile in aging population with type 2 diabetes mellitus

Background

Lipid metabolism disorder commonly happens in subjects with Type 2 diabetes mellitus (T2DM) which may be linked to genetic variants of lipid metabolism-related genes. However, few studies have explored the relationship between lipid metabolism-related gene polymorphism and serum lipid profile in aging subjects with T2DM. The present study was designed to explore the impact of genetic polymorphism of cluster determinant 36 (CD36) (rs1049673, rs1054516, rs2151916), scavenger receptor class B type 1 (SCARB1) (rs5888), and major facilitator superfamily domain containing the 2a (MFSD2A) (rs12083239, rs4233508, rs12072037) on the relationship between circulating lipids in aging subjects with T2DM.

Methods

205 T2DM patients and 205 age and gender matched control subjects were recruited. Information on demographic characteristics was collected by using a self-administered questionnaire. Fasting venous blood samples were taken for lipid-related gene genotyping and serum lipid profile measurement. The Chi-square test was used to compare percentage differences and to calculate P-value for Hardy-Weinberg equilibrium. Logistic regression and multiple linear regression were used to explore the risk or correlation between variables, and general linear model (GLM) was used to compare the means of serum lipids between the groups.

Results

In T2DM group, CD36 rs1054516 and MFSD2A rs12072037 were correlated with serum TC level. In control group, CD36 rs1049673 was correlated with serum HDL-C level. Meanwhile, T2DM subjects with MFSD2A rs12083239 (CG), MFSD2A rs4233508 (TT), and MFSD2A rs12072037 (AA) had higher TG level than control subjects. T2DM subjects with CD36 rs1049673 (CG, GG), CD36 rs1054516 (CT), CD36 rs2151916 (TT, CT), SCARB1 rs5888 (GG), MFSD2A rs12083239 (GG, CG), MFSD2A rs4233508 (TT), and MFSD2A rs12072037 (CA, AA) had lower HDL-C level than control subjects. T2DM subjects with MFSD2A rs12072037 (AA) had lower LDL-C level than control subjects. In dominant model, major genotype (GG) of SCARB1 gene was associated with the risk of T2DM (OR = 0.636, P = 0.032).

Conclusion

The genetic polymorphism of CD36 (rs1049673, rs1054516, rs2151916), SCARB1 (rs5888), and MFSD2A (rs12083239, rs4233508, rs12072037) were associated with serum lipids in T2DM subjects. The SCARB1 rs5888 major genotype (GG) was a protective factor for T2DM. Large scale cohort study is required to determine the relationship between lipid metabolism-related gene polymorphism, serum lipid profile and T2DM in aging subjects.

CD36 favours fat sensing and transport to govern lipid metabolism

CD36, located on the cell membrane, transports fatty acids in response to dietary fat. It is a critical fatty acid sensor and regulator of lipid metabolism. The interaction between CD36 and lipid dysmetabolism and obesity has been identified in various models and human studies. Nevertheless, the mechanisms by which CD36 regulates lipid metabolism and the role of CD36 in metabolic diseases remain obscure. Here, we summarize the latest research on the role of membrane CD36 in fat metabolism, with emphasis on CD36-mediated fat sensing and transport. This review also critically discusses the factors affecting the regulation of CD36-mediated fat dysfunction. Finally, we review previous clinical evidence of CD36 in metabolic diseases and consider the path forward.

Investigating the association of CD36 gene polymorphisms (rs1761667 and rs1527483) with T2DM and dyslipidemia: Statistical analysis, machine learning based prediction, and meta-analysis

CD36 (cluster of differentiation 36) is a membrane protein involved in lipid metabolism and has been linked to pathological conditions associated with metabolic disorders, such as diabetes and dyslipidemia. A case-control study was conducted and included 177 patients with type-2 diabetes mellitus (T2DM) and 173 control subjects to study the involvement of CD36 gene rs1761667 (G>A) and rs1527483 (C>T) polymorphisms in the pathogenesis of T2DM and dyslipidemia among Jordanian population. Lipid profile, blood sugar, gender and age were measured and recorded. Also, genotyping analysis for both polymorphisms was performed. Following statistical analysis, 10 different neural networks and machine learning (ML) tools were used to predict subjects with diabetes or dyslipidemia. Towards further understanding of the role of CD36 protein and gene in T2DM and dyslipidemia, a protein-protein interaction network and meta-analysis were carried out. For both polymorphisms, the genotypic frequencies were not significantly different between the two groups (p > 0.05). On the other hand, some ML tools like multilayer perceptron gave high prediction accuracy (≥ 0.75) and Cohen's kappa (κ) (≥ 0.5). Interestingly, in K-star tool, the accuracy and Cohen's κ values were enhanced by including the genotyping results as inputs (0.73 and 0.46, respectively, compared to 0.67 and 0.34 without including them). This study confirmed, for the first time, that there is no association between CD36 polymorphisms and T2DM or dyslipidemia among Jordanian population. Prediction of T2DM and dyslipidemia, using these extensive ML tools and based on such input data, is a promising approach for developing diagnostic and prognostic prediction models for a wide spectrum of diseases, especially based on large medical databases.

The influence of VDR polymorphisms on the type 2 diabetes susceptibility in Chinese: an interaction with hypertriglyceridemia

Evidence shows that mutations in vitamin D receptor (VDR) have been linked with an increased risk of type 2 diabetes (T2D). However, the interaction effect between VDR variants and environmental factors on the T2D susceptibility remained unclear. Therefore, the current study was conducted to explore the joint effect of VDR polymorphisms and serum triglyceride level on T2D. A total of 2017 participants were included in the cross-sectional study. Taqman probe assays were applied to rs3847987 and rs739837 genotyping. Multiple logistic regression and general linear model were used to examine the effect of interaction between VDR variants and TG on T2D susceptibility and fasting serum glucose, respectively. The results showed that rs739837 polymorphism was significantly associated with an increased risk of T2D under the dominant model (OR = 1.30, 95% CI 1.02-1.66), after adjusting for potential risk factors. Meanwhile, there was a significant additive interaction between rs3847987 and hypertriglyceridemia (synergy index [SI]: 2.98, 95% CI: 1.23-7.23) and between rs739837 and hypertriglyceridemia (SI: 2.36, 95% CI: 1.05-5.31) on T2D susceptibility. Additionally, a significant linear association between fasting glucose and rs3847987 had been found at high triglyceride level (> 1.90 mmol/L) with an inversely concentration-dependent manner. The study provided further evidence that rs739837 and high level of triglyceride were both associated with higher T2D susceptibility in Chinese population. Additionally, the detrimental effect of VDR variants on T2D could be modified by hypertriglyceridemia status.

CD36 in Alzheimer's Disease: An Overview of Molecular Mechanisms and Therapeutic Targeting

CD36 is a membrane protein with wide distribution in the human body, is enriched in the monocyte-macrophage system and endothelial cells, and is involved in the cellular uptake of long chain fatty acids (LCFA) and oxidized low-density lipoproteins. It is also a scavenger receptor, binding hydrophobic amyloid fibrils found in the Alzheimer's disease (AD) brain. In neurobiology research, it has been mostly studied in relationship with chronic ischemia and stroke, but it was also related to amyloid clearance by microglial phagocytosis. In AD animal models, amyloid binding to CD36 has been consistently correlated with a pro-inflammatory response. Therapeutic approaches have two main focuses: CD36 blockade with monoclonal antibodies or small molecules, which is beneficial in terms of the inflammatory milieu, and upregulation of CD36 for increased amyloid clearance. The balance of the two approaches, centered on microglia, is poorly understood. Furthermore, CD36 evaluation in AD clinical studies is still at a very early stage and there is a gap in the knowledge regarding the impact of LCFA on AD progression and CD36 expression and genetic phenotype. This review summarizes the role played by CD36 in the pathogenic amyloid cascade and explore the translatability of preclinical data towards clinical research.

The protective mechanisms of macroalgae Laminaria japonica consumption against lipid metabolism disorders in high-fat diet-induced hyperlipidemic rats

Macroalgae Laminaria japonica (MLJ) has been reported to exhibit various biological activities including improving immunity, anti-aging, anti-tumor, anti-atherosclerosis and anti-diabetic, but the protective mechanisms of MLJ consumption against non-alcoholic fatty liver disease (NAFLD) associated with hyperlipidemia remain poorly understood. This study demonstrated that MLJ consumption prevented high-fat diet (HFD)-induced NAFLD associated with hyperlipidemia in a rat model, and improved hyperlipidemia-related parameters, e.g. serum and hepatic lipid profiles. Moreover, histological analysis showed that MLJ reduced lipid deposition in adipocytes and hepatocytes compared with the HFD group. Such beneficial effects may be associated with the modulation of the intestinal microbiota, especially some key microbial phylotypes involved in lipid metabolism homeostasis. The underlying protective mechanisms of MLJ consumption against HFD-induced NAFLD associated with hyperlipidemia were also studied by ultra-high performance liquid chromatography with quadruple-time of flight mass spectrometry (UPLC-QTOF/MS)-based liver metabolomics coupled with pathway analysis. The metabolic pathway enrichment analysis of the differentially abundant hepatic metabolites indicated that primary bile acid biosynthesis metabolism and cysteine and methionine metabolism were the two main metabolic pathways altered by MLJ consumption when compared with the model group. The analysis of the transcription levels of liver-related genes by RT-qPCR and the expressions of liver-related proteins by immunohistochemistry (IHC) showed that MLJ consumption could regulate the levels of mRNA transcription and protein expression related to hepatic lipid metabolism. In short, this study indicates that MLJ could be developed as functional food supplement for the prevention or treatment of NAFLD associated with hyperlipidemia.

The Effect of Simvastatin on Gut Microbiota and Lipid Metabolism in Hyperlipidemic Rats Induced by a High-Fat Diet

The objective of this study was to investigate the effects of simvastatin (SIM) on lipid metabolism disorders and gut microbiota in high-fat diet-induced hyperlipidemic rats. The obtained results revealed that feeding rats with SIM (20 mg/kg/day) significantly decreased serum lipid level and inhibited hepatic lipid accumulation and steatosis. Histological analysis further indicated that SIM reduced lipid deposition in adipocytes and hepatocytes in comparison with that of the HFD group. The underlying mechanisms of SIM administration against HFD-induced hyperlipidemia were also studied by UPLC-Q-TOF/MS-based liver metabonomics coupled with pathway analysis. Metabolic pathway enrichment analysis of liver metabolites with significant difference in abundance indicated that fatty acids metabolism and amino acid metabolism were the main metabolic pathways altered by SIM administration. Meanwhile, operational taxonomic units (OTUs) analysis revealed that oral administration of SIM altered the composition of gut microbiota, including Ruminococcaceae (OTU960) and Lactobacillus (OTU152), and so on. Furthermore, SIM treatment also regulated the mRNA levels of the genes involved in lipid and cholesterol metabolism. Immunohistochemistry (IHC) analysis of the liver-related proteins (CD36, CYP7A1 and SREBP-1C) showed that oral administration of SIM could regulate the levels of the protein expression related to hepatic lipid metabolism.

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.

Plasma CD36 and Incident Diabetes: A Case-Cohort Study in Danish Men and Women

BACKGROUND

Membrane CD36 is a fatty acid transporter implicated in the pathogenesis of metabolic disease. We aimed to evaluate the association between plasma CD36 levels and diabetes risk and to examine if the association was independent of adiposity among Danish population.

METHODS

We conducted a case-cohort study nested within the Danish Diet, Cancer and Health study among participants free of cardiovascular disease, diabetes and cancer and with blood samples and anthropometric measurements (height, weight, waist circumference, and body fat percentage) at baseline (1993 to 1997). CD36 levels were measured in 647 incident diabetes cases that occurred before December 2011 and a total of 3,515 case-cohort participants (236 cases overlap).

RESULTS

Higher plasma CD36 levels were associated with higher diabetes risk after adjusting for age, sex and other lifestyle factors. The hazard ratio (HR) comparing high versus low tertile of plasma CD36 levels was 1.36 (95% confidence interval [CI], 1.00 to 1.86). However, the association lost its significance after further adjustment for different adiposity indices such as body mass index (HR, 1.23; 95% CI, 0.87 to 1.73), waist circumference (HR, 1.21; 95% CI, 0.88 to 1.68) or body fat percentage (HR, 1.20; 95% CI, 0.86 to 1.66). Moreover, raised plasma CD36 levels were moderately associated with diabetes risk among lean participants, but the association was not present among overweight/obese individuals.

CONCLUSION

Higher plasma CD36 levels were associated with higher diabetes risk, but the association was not independent of adiposity. In this Danish population, the association of CD36 with diabetes risk could be either mediated or confounded by adiposity.

Thrombospondin-1: A Key Protein That Induces Fibrosis in Diabetic Complications

Fibrosis accompanies most common pathophysiological features of diabetes complications in different organs. It is characterized by an excessive accumulation of extracellular matrix (ECM) components, the response to which contributes to inevitable organ injury. The extracellular protein thrombospondin-1 (TSP-1), a kind of extracellular glycoprotein, is upregulated by the increased activity of some transcription factors and results in fibrosis by activating multiple pathways in diabetes. The results of studies from our team and other colleagues indicate that TSP-1 is associated with the pathological process leading to diabetic complications and is considered to be the most important factor in fibrosis. This review summarizes the molecular mechanism of increased TSP-1 induced by hyperglycemia and the role of TSP-1 in fibrosis during the development of diabetes complications.

Viburnum opulus Fruit Phenolic Compounds as Cytoprotective Agents Able to Decrease Free Fatty Acids and Glucose Uptake by Caco-2 Cells

In recent years, there has been increasing interest in studying food-originated phytocompounds with beneficial influences for humans. Amongst the most active natural substances are polyphenols, for which high content has been identified in the Viburnum opulus berry, and which are unused in Western Europe. Due to its strong antioxidant activity we explored the potential of V. opulus as a preventive agent against diet-related chronic diseases, such as obesity and type 2 diabetes. Among the causes of these ailments is oxidative stress, as well as impaired glucose and free fatty acids (FFA) uptake. Thus, the purpose of this study was to determine biological activity of V. opulus phenolic extracts as cytoprotective agents able to decrease induced oxidative stress, lower lipid accumulation and attenuate glucose and FFA uptake by Caco-2 cells via GLUT2 and CD36/FAT transporters. To determine the source of the most biologically active phenolic compounds, we obtained four phenolic compounds extracts as crude juice, phenolics isolated from juice and two preparations of phenolics obtained with different extraction agents from fruit pomace. Among the studied extracts, the phenolic rich fraction obtained from fruit juice revealed the strongest activity to decrease uptake of glucose, FFA and accumulation of lipid droplets in Caco-2 cells without affecting their viability (IC₀ 50 μg/mL). Observed uptake attenuation was followed by decrease of the CD36/FAT gene expression, without influence on the GLUT2 and PPARα levels. We suspect that V. opulus phenolics were able to modulate the cellular membrane dynamic, although that hypothesis requires further, more detailed studies. Extracts revealed strong chemo-preventive activity against oxidative stress induced chemically by tert-butylhydroperoxide (t-BOOH), as well as against DNA damage through the induction of DNA repair after cell exposition to methylnitronitrosoguanidine (MNNG) and H₂O₂. Our findings suggest Viburnum opulus fruit as a dietary source of phytocompounds, which could be considered as a tailored design food supplement components for the prevention and treatment of postprandial elevation of glucose and fatty acids through delaying the rate of glucose and fatty acid absorption by intestinal cells.

Role of Natural Killer T (NKT) Cells in Type II Diabetes-Induced Vascular Injuries

Background

This study investigated the distribution and features of natural killer T (NKT) cells in the peripheral blood of diabetic patients, and their regulatory roles on vascular endothelial cells.

Material/Methods

Peripheral lymphocytes were isolated from diabetic patients. NKT cell distribution, proportion, and surface and intracellular markers were detected with flow cytometry. Peripheral blood-derived NKT cells were isolated and co-cultured with human umbilical vein endothelial cells (HUVECs). Proliferation and migration of HUVECs were assessed with the CCK-8 assay and the Transwell chamber assay.

Results

The ratios of CD3-CD56+ NK and CD3+CD56+ NKT cells in the peripheral blood of patients with type II diabetes were significantly elevated. The expression levels of NKp30, NKG2D, and NKp44 on the surface were increased in the CD3+CD56+ NKT cells, while the expression levels of NKG2A and 158b were significantly downregulated. The expression level of granzymes in the peripheral blood-derived NKT cells were not changed in patients with type II diabetes, but the expression levels of IFNγ and IL-4 were significantly increased. However, after co-culture with NKT cells derived from the peripheral blood of diabetic patients, the proliferation and migration of HUVECs were significantly inhibited, and was restored by treatment with IL-4 antibody. In addition, the IL-4 stimulus inhibited the proliferation and migration of HUVECs.

Conclusions

Peripheral blood NKT cells are increased and activated in diabetes. NKT cells inhibit the proliferation and migration of HUVECs by secreting IL-4, thereby inducing vascular injuries.