Abstract

Background: Intestine epithelial HIF-1α plays a critical role in the maintaining of gut barrier function. Disrupted gut barrier function contributes to the development of metabolic syndrome. The aim of this study is to determine whether pharmacological or genetic activation of intestinal HIF-1α ameliorates western diet-induced MASLD and metabolic syndrome.

Methods: Hif1α^{LSL/LSL;VilERcre} and Hif1α^LSL/LSL mice were generated by crossing LSL-HIF1 dPA mice with villin-cre-ERT2 mice. The intestine Hif1α activation was induced by tamoxifen administration. Male adult Hif1α^LSL/LSL and Hif1α^{LSL/LSL;VilERcre} mice were fed with regular chow diet, high fructose (HFr) or high-fat (60% Kcal) high-fructose diet (HFHFr) for 8 weeks. High fructose diet was given via 30% fructose (w/v) in the drinking water ad lib for 8 weeks. Glucose and insulin tolerance test, and liver histology were evaluated. Ileum transcriptome was assessed by bulk RNA-seq. 8- to 10-week-old male HIF-1α luciferase reporter (ODD-luc) mice were fed with chow with or without 30% fructose (w/v) in the drinking water ad lib for 2 weeks and treated with dimethyloxalylglycine (DMOG), a pharmacological activator of HIF-1, at the dose of 8mg/mouse via IP injection every second day for 2 weeks. At the end of experiment, the luciferase activities of the entire GI tract were evaluated by bioluminescence imaging (BLI). Blood glucose level and cecal stool 16S rRNA sequencing were evaluated.

Results: Hif1α^{LSL/LSL;VilERcre} mice exhibited markedly improved glucose tolerance compared to Hif1α^LSL/LSL mice in response to HFr diet. Intestine-specific Hif1α-overexpression led to markedly improved hepatic steatosis and a trend of decreased liver/body weight ratio without obvious alteration in the body weight when exposed to HFHFr diet. Of note, intestine-specific Hif1α-overexpression led to increased white adipose tissue (eWAT) weight and a trend of increased cecum/body weight ratio. DMOG treatment led to increased intestine HIF luciferase activity as shown by BLI and decreased blood glucose level associated with a remarkable alterations of gut microbiota composition in HFr diet fed ODD-luc mice. Ileum RNA-seq data analysis revealed that GO terms, including glycolytic process, pyruvate metabolic process, ATP generation from ADP were upregulated in Hif1α^{LSL/LSL;VilERcre} mice. KEGG enrichment analysis further showed that glycolysis/gluconeogenesis was up in Hif1α^{LSL/LSL;VilERcre} mice.

Conclusion: Our data provide evidence that pharmacological or genetic activation of intestinal HIF-1α markedly ameliorate western diet-induced MASLD and metabolic phenotypes. RNA-seq data suggest that intestinal HIF-1α activation upregulates glycolysis, presumably leading to enhanced cell proliferation. Intestinal HIF-1α could be a promising therapeutic target for the treatment of MASLD and metabolic syndrome.