Aflatoxin B1 Induces Gut-Inflammation-Associated Fecal Lipidome Changes in F344 Rats

Abstract

Aflatoxin B1 (AFB1) induced intestinal epithelial damage in rodent models, which indicates that long-term exposure to AFB1 may cause chronic gut disorders. In this study, we tested the hypothesis that AFB1-induced adverse effects on gut is mediated by gut-microbiota, which is partially reflected by the changes of fecal microbiome and metabolome. F344 rats were orally exposed to AFB1 of 0, 5, 25, and 75 µg kg-1 body weight for 4 weeks and fecal samples were collected. An ion-fragmentation-spectrum-based metabolomics approach was developed to investigate the fecal microbiota-associated metabolic changes in fecal samples. We found that AFB1 inhibited the hepatic and intestinal metabolism of bile constituents. As compared with the controls, bile acid synthesis-associated cholesterols in rats treated with 25 µg kg-1 (the middle-dose group) were significantly decreased in the fecal samples, for example, lathosterol (45% reduction), cholesterol ester (21% reduction), chenodeoxycholic acid (20% reduction), dihydroxycholesterol (55% reduction), hydroxycholesterol (20% reduction), and 5-cholestene (29% reduction). Although disease-associated lipids were not detectable in the feces of the control group, they were found in AFB1-treated groups, including diglyceride, monoacylglyceride, 19,20-dihydroxy-docosapentaenoic acid, and phosphatidylethanolamine. Metabolisms of carbohydrates and production of short-chain fatty acids were remarkedly decreased in all treated groups. Moreover, an inflammatory-bowel-disease (IBD)-associated taxonomic structure of fecal microbiota was observed as ∼25% Lachnospiraceae, ∼25% Ruminococcaceae, and <1% Lactobacillales, which was similar to the composition pattern found in IBD patients. These results suggest that AFB1-induced disruption on gut-microbiota, partially reflected by fecal microbiome and metabolome, may play important roles in the pathogenesis of chronic gut disorders.

Keywords: aflatoxin B1; chronic gut disorders; gut-microbiota; ion-fragmentation-spectrum-based metabolomics; lipidome.