Effects of high-soy diet on S100 gene expression in liver and intestine of rainbow trout (Oncorhynchus mykiss).

The current study examines expression of S100 genes, a group of calcium-sensing proteins poorly characterized in fishes. In mammals, these proteins are known to play roles beyond calcium-signaling, including mediation of inflammatory processes. Some S100 proteins also serve as biomarkers for a variety of autoinflammatory conditions. It is well known that salmonids exhibit varying degrees of intestinal enteritis when exposed to alternative feed ingredients containing antinutritional factors, with soybean meal (SBM) being one of the best characterized. The etiology of soy-caused distal enteritis isn't entirely understood but displays similar histopathological alterations to the gut observed in human mucosal inflammatory bowel diseases. We sought to determine if teleost S100 genes show a concomitant response like that observed in mammals, utilizing rainbow trout fed high-soy diets as a model for intestinal inflammation. We examined expression of fourteen known salmonid S100 genes in the liver, first segment of the mid-intestine (proximal intestine), and second segment of the mid-intestine (distal intestine). After 12 weeks on a high-soy diet containing 40% SBM, we observed upregulation of several S100 genes in the distal intestine (S100I2, A10a, V1, V2, and W), no changes in the proximal intestine, and downregulation of S100V2 in the liver. Overall, our results provide further knowledge of the expression of S100 genes and provide targets for future research regarding inflammatory processes in the rainbow trout gut.