Intestinal microbiota transplantation reveals the role of microbiota in dietary regulation of RegIII beta and RegIII gamma expression in mouse intestine

RegIII beta and RegIII gamma are antimicrobial peptides expressed in intestinal epithelial cells. Expression of these peptides is reportedly decreased by high-fat diet (HFD) and increased by indigestible oligosaccharides in mice. Clearly, these dietary regimens change the structure of intestinal microbiota. We employed an intestinal microbiota transplantation (IMT) to test whether diet-induced changes in the expression of these peptides are mediated by gut microbiota. C57BL/61 mice were fed either a normal-fat diet (NFD), a HFD, or a NFD supplemented with or without 1-kestose (KES), an indigestible oligosaccharide. Ileal RegIII beta and RegIII gamma mRNA levels were lower in mice receiving IMT from HFD-fed mice than in those receiving NFD-fed mice and higher in mice receiving IMT from KES-supplemented mice than in those receiving the mice without KES supplementation. Western blot analysis showed that serum RegIII beta levels changed in parallel with the ileal mRNA levels. We propose that HFD- and KES-induced changes in the ileal RegIII beta and RegIII gamma expression and in the circulating RegIII beta levels are mediated, at least in part, by intestinal microbiota. (C) 2020 Elsevier Inc. All rights reserved