Gut microbiota induces hepatic steatosis by modulating the T cells balance in high fructose diet mice

Metabolic diseases are often associated with high fructose (HF) consumption. HF has also been found to alter the gut microbiota, which then favors the development of nonalcoholic fatty liver disease. However, the mechanisms underlying of the gut microbiota on this metabolic disturbance are yet to be determined. Thus, in this study, we further explored the effect the gut microbiota concerning the T cells balance in an HF diet mouse model. We fed mice 60% fructose-enriched diet for 12 weeks. At 4 weeks, HF diet did not affect the liver, but it caused injury to the intestine and adipose tissues. After 12 weeks, the lipid droplet aggregation was markedly increased in the liver of HF-fed mice. Further analysis of the gut microbial composition showed that HF decreased the Bacteroidetes/Firmicutes ratio and increased the levels of Blautia, Lachnoclostridium, and Oscillibacter. In addition, HF can increase the expression of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in the serum. T helper type 1 cells were significantly increased, and regulatory T(Treg) cells were markedly decreased in the mesenteric lymph nodes of the HF-fed mice. Furthermore, fecal microbiota transplantation alleviates systemic metabolic disorder by maintaining liver and intestinal immune homeostasis. Overall, our data indicated that intestinal structure injury and intestinal inflammation might be early, and liver inflammation and hepatic steatosis may be a subsequent effect following HF diets. Gut microbiota disorders impairing the intestinal barrier function and triggering immune homeostasis imbalance may be an importantly responsible for long-term HF diets induced hepatic steatosis.