Sexual dimorphism in glucose metabolism is shaped by androgen-driven gut microbiome.

Males are generally more susceptible to impaired glucose metabolism and type 2 diabetes (T2D) than females. However, the underlying mechanisms remain to be determined. Here, we revealed that gut microbiome depletion abolished sexual dimorphism in glucose metabolism. The transfer of male donor microbiota into antibiotics-treated female mice led the recipients to be more insulin resistant. Depleting androgen via castration changed the gut microbiome of male mice to be more similar to that of females and improved glucose metabolism, while reintroducing dihydrotestosterone (DHT) reversed these alterations. More importantly, the effects of androgen on glucose metabolism were largely abolished when the gut microbiome was depleted. Next, we demonstrated that androgen modulated circulating glutamine and glutamine/glutamate (Gln/Glu) ratio partially depending on the gut microbiome, and glutamine supplementation increases insulin sensitivity in vitro. Our study identifies the effects of androgen in deteriorating glucose homeostasis partially by modulating the gut microbiome and circulating glutamine and Gln/Glu ratio, thereby contributing to the difference in glucose metabolism between the two sexes.

Grape seed proanthocyanidin extract ameliorates inflammation and adiposity by modulating gut microbiota in high-fat diet mice.

SCOPE: Obesity and associated metabolic complications is a worldwide public health issue. Gut microbiota have been recently linked to obesity and its related inflammation. In this study, we have explored the anti-inflammatory effect of grape seed proanthocyanindin extract (GSPE) in the high-fat diet (HFD)-induced obesity and identified the contribution of the gut microbiota to GSPE effects on metabolism. METHODS AND RESULTS: Mice were fed a normal diet and a high-fat diet with or without GSPE (300 mg/kg body weight/day) by oral gavage for 7 weeks. Supplementation with GSPE significantly decreased plasma levels of inflammatory factors such as TNF-α, IL-6 and MCP-1, companied with ameliorated macrophage infiltration in epidydimal fat and liver tissues. Furthermore, GSPE also reduced epidydimal fat mass and improved insulin sensitivity. 16S rDNA analyses revealed that GSPE supplementation modulated the gut microbiota composition and certain bacteria including Clostridium XIVa, Roseburia and Prevotella. More importantly, depleting gut microbiota by antibiotics treatment abolished the beneficial effects of GSPE on inflammation and adiposity. CONCLUSION: Our study identifies the novel links between gut microbiota alterations and metabolic benefits by GSPE supplementation, providing possibilities for the prevention and treatment of metabolic disorders by targeting gut microbiota through a potential prebiotic agent GSPE.

Akkermansia muciniphila improves metabolic profiles by reducing inflammation in chow diet-fed mice.

Abnormal shifts in the composition of gut microbiota contribute to the pathogenesis of metabolic diseases, including obesity and type 2 diabetes (T2DM). The crosstalk between gut microbes and the host affects the inflammatory status and glucose tolerance of the individuals, but the underlying mechanisms have not been elucidated completely. In this study, we treated the lean chow diet-fed mice with Akkermansia muciniphila, which is thought to be inversely correlated with inflammation status and body weight in rodents and humans, and we found that A. muciniphila supplementation by daily gavage for five weeks significantly alleviated body weight gain and reduced fat mass. Glucose tolerance and insulin sensitivity were also improved by A. muciniphila supplementation compared with the vehicle. Furthermore, A. muciniphila supplementation reduced gene expression related to fatty acid synthesis and transport in liver and muscle; meanwhile, endoplasmic reticulum (ER) stress in liver and muscle was also alleviated by A. muciniphila. More importantly, A. muciniphila supplementation reduced chronic low-grade inflammation, as reflected by decreased plasma levels of lipopolysaccharide (LPS)-binding protein (LBP) and leptin, as well as inactivated LPS/LBP downstream signaling (e.g. decreased phospho-JNK and increased IKBA expression) in liver and muscle. Moreover, metabolomics profiling in plasma also revealed an increase in anti-inflammatory factors such as α-tocopherol, ß-sitosterol and a decrease of representative amino acids. In summary, our study demonstrated that A. muciniphila supplementation relieved metabolic inflammation, providing underlying mechanisms for the interaction of A. muciniphila and host health, pointing to possibilities for metabolic benefits using specific probiotics supplementation in metabolic healthy individuals.