Obesity, adipocytes and insulin resistance-Friends for life?

In Vitro Effects of Cyanidin-3-O-Glucoside on Inflammatory and Insulin-Sensitizing Genes in Human Adipocytes Exposed to Palmitic Acid

In this article, we investigated the in vitro potential beneficial effects of the anthocyanin cyanidin-3-O-glucoside (C3G) on inflammation and insulin resistance markers induced by palmitic acid (PA) in human SGBS adipocytes. Results demonstrated that PA reduced insulin sensitivity in SGBS cells with a significant inhibition of Akt phosphorylation, with a higher sensitivity to PA than murine 3T3-L1 adipocytes, GLUT-1 and GLUT-4 glucose transporters and the enzyme hexokinase-II. C3G pretreatment (1-20 μM) reverted these effects. Moreover, we demonstrated, for the first time in human adipocytes, that cells exposure to PA induced gene expression of proinflammatory cytokines TNF-α, IL-6, IL-8, and MCP-1. Cells pretreatment with C3G resulted in a reduction in mRNA levels starting at very low concentrations (1 μM). In conclusion, this study highlights the effects of PA on inflammation and insulin resistance markers in human adipocytes, and confirm the role of C3G in the prevention of lipotoxicity in dysfunctional adipocytes.

Spermidine ameliorates high-fat diet-induced hepatic steatosis and adipose tissue inflammation in preexisting obese mice

AIMS

The therapeutic effects of spermidine on preexisting obese mice have been not fully elucidated. In this study, we assessed the anti-obesity impact of spermidine on high-fat diet (HFD)-induced obese mice.

MAIN METHODS

C57BL/6J mice were fed a HFD for 16 weeks to induce obesity, and then treated with or without spermidine via drinking water for additional 8 weeks. The contributions of spermidine in regulating obesity phenotypes and metabolic syndrome were further evaluated.

KEY FINDINGS

Spermidine administration lowered fat mass and plasma lipid profile in HFD-induced obese mice without affecting body weight. In addition, spermidine attenuated hepatic steatosis by regulating lipid metabolism and enhancing antioxidant capacity. Moreover, spermidine reduced adipose tissue inflammation by decreasing inflammatory cytokine and chemokines expression, and these results might contributed to the enhanced thermogenic gene expression in brown adipose tissue. Furthermore, spermidine treatment enhanced gut barrier function by up-regulating tight junction- and mucin-related gene expression.

SIGNIFICANCE

Spermidine-mediated protective impacts involve the regulation of lipid metabolism, inflammation response, gut barrier function and thermogenesis. These findings demonstrate that spermidine has potentials in treating obesity.

Anti-adipogenesis and metabolism-regulating effects of heat-inactivated Streptococcus thermophilus MN-ZLW-002

Metabolic syndrome and obesity have become serious threats to public health worldwide. This study was conducted to evaluate the anti-adipogenesis and metabolism-regulating effects of heat-inactivated Streptococcus thermophilus MN-ZLW-002 (MN-ZLW-002), which can be used as a yogurt starter. In vitro study suggested that MN-ZLW-002 stimulated the RAW264.7 macrophages to produce significant amounts of interleukin (IL)-6, IL-10 and tumour necrosis factor (TNF)-α and induced intense phosphorylation of P38, p44/42 MAPK and nuclear factor κB. MN-ZLW-002-stimulated RAW264.7-conditioned medium (CM) notably suppressed the differentiation and adipogenesis of 3T3-L1 pre-adipocytes. The 12-week in vivo study suggested that orally administered MN-ZLW-002 significantly reduced the weight gain of mice caused by the high-fat diet (HFD) at weeks 3-8; decreased fasting blood glucose levels at week 4 and week 8; decreased serum total triglyceride level at week 12. MN-ZLW-002 also reduced serum IL-1β and chemokine ligand 3 levels in the HFD-fed mice. These findings suggest that heat-inactivated MN-ZLW-002 can suppress adipocytes differentiation and lipid accumulation by regulating the immune response, possibly via the release of cytokines, particularly TNF-α; MN-ZLW-002 can improve metabolism-related indicators in the early stage of HFD intervention and regulate the related pro-inflammatory immune response.

Probiotic Mixture of Lactobacillus plantarum Strains Improves Lipid Metabolism and Gut Microbiota Structure in High Fat Diet-Fed Mice

The global prevalence of obesity is rising year by year, which has become a public health problem worldwide. In recent years, animal studies and clinical studies have shown that some lactic acid bacteria possess an anti-obesity effect. In our previous study, mixed lactobacilli (Lactobacillus plantarum KLDS1.0344 and Lactobacillus plantarum KLDS1.0386) exhibited anti-obesity effects in vivo by significantly reducing body weight gain, Lee's index and body fat rate; however, its underlying mechanisms of action remain unclear. Therefore, the present study aims to explore the possible mechanisms for the inhibitory effect of mixed lactobacilli on obesity. C57BL/6J mice were randomly divided into three groups including control group (Control), high fat diet group (HFD) and mixed lactobacilli group (MX), and fed daily for eight consecutive weeks. The results showed that mixed lactobacilli supplementation significantly improved blood lipid levels and liver function, and alleviated liver oxidative stress. Moreover, the mixed lactobacilli supplementation significantly inhibited lipid accumulation in the liver and regulated lipid metabolism in epididymal fat pads. Notably, the mixed lactobacilli treatment modulated the gut microbiota, resulting in a significant increase in acetic acid and butyric acid. Additionally, Spearman's correlation analysis found that several specific genera were significantly correlated with obesity-related indicators. These results indicated that the mixed lactobacilli supplementation could manipulate the gut microbiota and its metabolites (acetic acid and butyric acid), resulting in reduced liver lipid accumulation and improved lipid metabolism of adipose tissue, which inhibited obesity.

Indirubin promotes adipocyte differentiation and reduces lipid accumulation in 3T3‑L1 cells via peroxisome proliferator‑activated receptor γ activation

The peroxisome proliferator‑activated receptor γ (PPARγ) plays an important role in insulin sensitivity and adipocyte differentiation. It is known as ligand‑receptor that improves insulin sensitivity in type 2 diabetes mellitus. Several kinds of indigo plant have been already used to treat diabetes in oriental traditional medicine, but its mechanism has not been clarified yet. To investigate the effect of indirubin, which is a component of Polygonum tinctorium on the cell differentiation and adipprocess in 3T3‑L1 cells, 3T3‑L1 cells were cultured to determine the effect of cell differentiation and glucose uptake with indirubin. As a result, Indirubin compound enhanced adipocyte differentiation in 3T3‑L1 cells similar to rosiglitazone. This effect was terminated by cotreatment with GW9662, a PPARγ antagonist. In mature 3T3‑L1 adipocytes, the lipid droplet size and accumulation were reduced by this compound. The basal and insulin‑stimulated glucose uptakes were also significantly increased. In addition, indirubin treatment significantly enhanced estrogen level by 1.64‑fold with mature adipocytes which can be attributed to its aromatase activity. Conclutionaly, this finding suggested that indirubin is a potential anti‑diabetic compound for type 2 diabetes mellitus by promoting adipocyte differentiation and glucose uptake via PPARγ.