Leptin and adiponectin synthesis and secretion in mature 3T3-L1 adipocytes are differentially down-regulated by arsenic and palmitic acid exposure throughout different stages of adipogenesis

Lipotoxicity: The missing link between diabetes and periodontitis?

Lipotoxicity refers to the accumulation of lipids in tissues other than adipose tissue (body fat). It is one of the major pathophysiological mechanisms responsible for the progression of diabetes complications such as non-alcoholic fatty liver disease and diabetic nephropathy. Accumulating evidence indicates that lipotoxicity also contributes significantly to the toxic effects of diabetes on periodontitis. Therefore, we reviewed the current in vivo, in vitro, and clinical evidence of the detrimental effects of lipotoxicity on periodontitis, focusing on its molecular mechanisms, especially oxidative and endoplasmic reticulum stress, inflammation, ceramides, adipokines, and programmed cell death pathways. By elucidating potential therapeutic strategies targeting lipotoxicity and describing their associated mechanisms and clinical outcomes, including metformin, statins, liraglutide, adiponectin, and omega-3 PUFA, this review seeks to provide a more comprehensive and effective treatment framework against diabetes-associated periodontitis. Furthermore, the challenges and future research directions are proposed, aiming to contribute to a more profound understanding of the impact of lipotoxicity on periodontitis.

Interleukin-16 is increased in obesity and alters adipogenesis and inflammation in vitro

Introduction

Obesity is a chronic condition associated with low-grade inflammation mainly due to immune cell infiltration of white adipose tissue (WAT). WAT is distributed into two main depots: subcutaneous WAT (sWAT) and visceral WAT (vWAT), each with different biochemical features and metabolic roles. Proinflammatory cytokines including interleukin (IL)-16 are secreted by both adipocytes and infiltrated immune cells to upregulate inflammation. IL-16 has been widely studied in the peripheral proinflammatory immune response; however, little is known about its role in adipocytes in the context of obesity.

Aim & Methods

We aimed to study the levels of IL-16 in WAT derived from sWAT and vWAT depots of humans with obesity and the role of this cytokine in palmitate-exposed 3T3-L1 adipocytes.

Results

The results demonstrated that IL-16 expression was higher in vWAT compared with sWAT in individuals with obesity. In addition, IL-16 serum levels were higher in patients with obesity compared with normal-weight individuals, increased at 6 months after bariatric surgery, and at 12 months after surgery decreased to levels similar to before the intervention. Our in vitro models showed that IL-16 could modulate markers of adipogenesis (Pref1), lipid metabolism (Plin1, Cd36, and Glut4), fibrosis (Hif1a, Col4a, Col6a, and Vegf), and inflammatory signaling (IL6) during adipogenesis and in mature adipocytes. In addition, lipid accumulation and glycerol release assays suggested lipolysis alteration.

Discussion

Our results suggest a potential role of IL-16 in adipogenesis, lipid and glucose homeostasis, fibrosis, and inflammation in an obesity context.

Baicalein enhances immune response in TNBC by inhibiting leptin expression of adipocytes

Triple-negative breast cancer (TNBC) is a special pathological type of breast cancer (BC) with poor prognosis. Obesity is shown to be involved in TNBC tumor progression. The interaction between obesity and BC has generated great attention in recent years, however, the mechanism is still unclear. Here, we showed that leptin secreted by adipocytes upregulated PD-L1 expression in TNBC through the p-STAT3 signaling pathway and that baicalein inhibited PD-L1 expression in tumor microenvironment by suppressing leptin transcription of adipocytes. Collectively, our findings suggest that leptin may be the key factor participating in obesity-related tumor progression and that baicalein can break through the dilemma to boost the anti-tumor immune response.

WKYMVm ameliorates obesity by improving lipid metabolism and leptin signalling

Obesity is a metabolic disorder that results from an imbalance of energy intake and consumption. As low-grade chronic inflammation caused by obesity can lead to various complications, it is important to develop effective treatments against obesity. In this study, we investigate the effects of WKYMVm, a strong anti-inflammatory agent, against obesity. Administration of WKYMVm into high fat diet (HFD)-induced obese mice significantly attenuated body weight gain, food intake and increased insulin sensitivity. HFD-induced hepatic steatosis and adipose tissue hypertrophy were also markedly ameliorated by WKYMVm. During the maturation of adipocytes, WKYMVm improves lipid metabolism by increasing lipolysis, adipogenesis, mitochondrial biogenesis and fat browning. WKYMVm administration also elicited a decrease in leptin levels, but an increase in leptin sensitivity via regulation of hypothalamic endoplasmic reticulum stress and the leptin receptor cascade. Taken together, our results show that WKYMVm ameliorates obesity by improving lipid metabolism and leptin signalling, suggesting that WKYMVm can be a useful molecule for the development of anti-obesity agents.

Protopanaxadiol-Enriched Rice Exerted Antiadipogenic Activity during 3T3-L1 Differentiation and Anti-Inflammatory Activity in 3T3-L1 Adipocytes

Ginseng is a traditional medicine with health benefits for humans. Protopanaxadiol (PPD) is an important bioactive compound found in ginseng. Transgenic rice containing PPD has been generated previously. In the present study, extracts of this transgenic rice were evaluated to assess their antiadipogenic and anti-inflammatory activities. During adipogenesis, cells were treated with transgenic rice seed extracts. The results revealed that the concentrations of the rice seed extracts tested in this study did not affect cell viability at 3 days post-treatment. However, the rice seed extracts significantly reduced the accumulation of lipids in cells and suppressed the activation of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ), which in turn inhibited the expression of adipogenesis-related mRNAs, such as adiponectin, PPARγ, C/EBPα, sterol regulatory element-binding protein 1, glucose transport member 4, and fatty acid synthase. In adipocytes, the extracts significantly reduced the mRNA expression of inflammation-related factors following LPS treatment. The activation of NF-κB p65 and ERK 1/2 was inhibited in extract-treated adipocytes. Moreover, treatment with extract #8 markedly reduced the cell population of the G2/M phase. Collectively, these results indicate that transgenic rice containing PPD may act as an obesity-reducing and/or -preventing agent.

Germinated Rice Seeds Improved Resveratrol Production to Suppress Adipogenic and Inflammatory Molecules in 3T3-L1 Adipocytes

Obesity is a major risk factor for a variety of diseases and contributes to chronic inflammation. Resveratrol is a naturally occurring antioxidant that can reduce adipogenesis. In this study, the antiadipogenic and anti-inflammatory activities of resveratrol-enriched rice were investigated in 3T3-L1 adipocyte cells. Cotreatment of dexamethasone and isobutylmethylxanthin upregulated adipogenic transcription factors and signaling pathways. Subsequent treatment of adipocytes with rice seed extracts suppressed the differentiation of 3T3-L1 by downregulating adipogenic transcription factors (peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α) and signaling pathways (extracellular signal-regulated kinase 1/2 and protein kinase B Akt), this was especially observed in cells treated with germinated resveratrol-enriched rice seed extract (DJ526_5). DJ526_5 treatment also markedly reduced lipid accumulation in the cells and expression of adipogenic genes. Lipopolysaccharide (LPS)-induced inflammatory cytokines (prostaglandin-endoperoxide synthase 2 (COX-2), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6) decreased in cells treated with DJ526_5. Collectively, DJ526_5 exerts antiadipogenic effects by suppressing the expression of adipogenesis transcription factors. Moreover, DJ526_5 ameliorates anti-inflammatory effects in 3T3-L1 adipocytes by inhibiting the activation of phosphorylation NF-κB p65 and ERK ½ (MAPK). These results highlight the potential of resveratrol-enriched rice as an alternative obesity-reducing and anti-inflammatory agent.

Is Arsenic Exposure a Risk Factor for Metabolic Syndrome? A Review of the Potential Mechanisms

Exposure to arsenic in drinking water is a worldwide health problem. This pollutant is associated with increased risk of developing chronic diseases, including metabolic diseases. Metabolic syndrome (MS) is a complex pathology that results from the interaction between environmental and genetic factors. This condition increases the risk of developing type 2 diabetes, cardiovascular diseases, and cancer. The MS includes at least three of the following signs, central obesity, impaired fasting glucose, insulin resistance, dyslipidemias, and hypertension. Here, we summarize the existing evidence of the multiple mechanisms triggered by arsenic to developing the cardinal signs of MS, showing that this pollutant could contribute to the multifactorial origin of this pathology.