Cecal Microbiota Dysbiosis and Hepatic Transcriptomic Alterations in Western Diet‐Induced NASH in Juvenile Ossabaw Swine

Abstract

Pediatric nonalcoholic steatohepatitis (NASH) rates are on the rise in industrialized nations, yet the mechanisms that contribute to disease development remain poorly defined. Here we sought to test the hypothesis that western diet (WD)‐induced NASH in obese juvenile Ossabaw swine is linked to cecal dysbiosis and altered markers of intestinal permeability, as well as to determine RNA transcriptomic changes within the liver in this model of pediatric NASH. Sixteen weeks of WD (high fat, fructose, cholesterol) feeding caused obesity and a severe NASH phenotype, including hepatocellular ballooning, inflammation, and fibrosis compared with lean pigs fed low fat chow. WD feeding induced marked cecal dysbiosis, including decreases in the relative abundance of Firmicutes (70% vs 50%, P<0.05) and a 6‐fold increase in Proteobacteria (23% vs 4%, p<0.001) vs chow fed pigs. Specifically, WD‐feeding increased relative abundances of classes Gammaproteobacteria and Deltaproteobacteria (gram‐negative genera Eschericia coli and Shigella) which are linked to endotoxemia, inflammation and intestinal permeability. The observed dysbiosis was associated with down regulation of jejunal mRNA expression of tight junction proteins ZO‐1 and ZO‐2, and increased mucosal cell expression of inflammatory markers CD‐14, TLR2, TLR4, and IL‐1β in obese WD‐fed pigs. RNA‐sequencing analyses revealed 2168 up‐ and 67 down‐regulated mRNA transcripts (≥ 2.0 fold, FDR <0.10) in liver between WD and chow fed swine. The top regulated canonical pathways identified by Ingenuity Pathway Analysis were “Interferon Signaling”, “Hepatic Fibrosis/Hepatic Stellate Cell Activation”, and “Antigen Presentation Pathway”. Collectively, these data demonstrate that WD feeding in juvenile Ossabaw swine induces cecal dysbiosis, alters markers of intestinal permeability, and causes robust transcriptomic changes in the liver that may contribute to NASH.Support or Funding InformationMizzou Advantage, Allen Foundation, and VA‐CDA2 IK2BX001299 (RSR)