(866.1) Dietary Tryptophan-Lactobacillus rhamnosus GG Interactions Modify Intestinal Differentiation and Function

Poster Board Number: E199

Panan Suntornsaratoon (Rutgers New Jersey Medical School), Juan Flores (Biological Sciences, Rutgers University), Ravij Upadhyay (Rutgers New Jersey Medical School), Paula Lopez (Rutgers New Jersey Medical School), Radha Patel (Biological Sciences, Rutgers University), Sheila Bandyopadhyay (Biological Sciences, Rutgers University), Nan Gao (Biological Sciences, Rutgers University), Ronaldo Ferraris (Rutgers New Jersey Medical School)

Although the influence of the gut microbiota on structure and proliferation of intestinal epithelial cells has been established, there is disconcordance on information related to cell type differentiation, because most studies on probiotics reflected an outcome from interactions among Lactobacillus, numerous existing microbes, and the host, with limited insight on the specific impact of Lactobacilli spp.  For example, L. reuteri enhanced goblet and Paneth cell differentiation in intestine of conventionally-raised chickens with an established commensal gut microbiota, confounding results. Here we fed gnotobiotic mice with tryptophan (t+) or trp-free (t–) diets, followed by monocolonization with LGG (L+, ATCC 53103) or without (control, L–) for a total of 4 groups (L+t+, L+t–, L–t+, L–,t–), then ileum transcriptome was analyzed 3 wk later.  L– mice remained germ-free throughout while only LGG was associated with L+. Principal component analysis shows L+ or t+ by itself to modestly cluster away from L–t–, but the cluster depicting the combination of L+t+ was far removed from the others. The heatmap of whole ileum transcriptome shows several distinct groups of genes affected by t+ or by L+ alone.  However, the simultaneous impact of L+t+ dramatically upregulates numerous gene clusters while downregulating a few.  Volcano plots and Venn diagrams comparing L–t– with L–t+, or L+t– with L–t– indicate ~2300 unique genes affected by L+ (LGG) or t+ (tryptophan) alone.  Comparisons between L+t+ and L+t– (effect of t with L) or between L+t+ and L–t+ (effect of L with t) each impact gt;3800 genes, suggesting that synergistic interactions between L+ and t+ primarily underlie the probiotic impact ascribed to LGG and dietary t.  Many of the genes upregulated by L+t+ have functions typical of mature enterocytes: tight junctions, brush border membrane transporters and enzymes, intestinal bile acid metabolism, lipid synthesis and fatty acid b-oxidation.  Many downregulated genes are antimicrobial and secreted peptides typical of differentiated Paneth and goblet cells. This latter result was recapitulated when reexamined in conventional mice perfused for 4 h with LGG, as expression of many defensins decreased by gt;10-fold, suggesting not only that this probiotic’s effects can arise from both acute ex vivo and chronic in vivo interactions with the host, but also in hosts housing a complex microbiota.  Remarkably, Notch ligands Dll1 and Dll4 typically expressed in Paneth cells as well as Yap1, Axin2 and Ctnnb1 are upregulated in L+t+ ileum, suggesting downstream upregulation of Hes1 and repression of Atoh1, leading to suppression of the secretory lineage.  In conclusion, LGG monocolonization may lead to synthesis of t+-derived metabolites by both host and bacteria, leading to an enhancement of absorptive enterocyte functions and suppression of those by goblet and Paneth cells.

NIHR01-AT010243 (NG,RF), R01DK119198 (NG), NSF 1754783 (RF).