Microbiota of the Small Intestine Is Selectively Engulfed by Phagocytes of the Lamina Propria and Peyer’s Patches

Abstract

Phagocytes such as dendritic cells and macrophages, which are distributed in the small intestinal mucosa, play a crucial role in maintaining mucosal homeostasis by sampling the luminal gut microbiota. However, there is limited information regarding microbial uptake in a steady state. We investigated the composition of murine gut microbiota that is engulfed by phagocytes of specific subsets in the small intestinal lamina propria (SILP) and Peyer’s patches (PP). Analysis of bacterial 16S rRNA gene amplicon sequences revealed that: 1) all the phagocyte subsets in the SILP primarily engulfed Lactobacillus (the most abundant microbe in the small intestine), whereas CD11bhi and CD11bhiCD11chi cell subsets in PP mostly engulfed segmented filamentous bacteria (indigenous bacteria in rodents that are reported to adhere to intestinal epithelial cells); and 2) among the Lactobacillus species engulfed by the SILP cell subsets, L. murinus was engulfed more frequently than L. taiwanensis, although both these Lactobacillus species were abundant in the small intestine under physiological conditions. These results suggest that small intestinal microbiota is selectively engulfed by phagocytes that localize in the adjacent intestinal mucosa in a steady state. These observations may provide insight into the crucial role of phagocytes in immune surveillance of the small intestinal mucosa.

Dietary supplementation with spray-dried porcine plasma has prebiotic effects on gut microbiota in mice

“…It is worth noting that L. antri and L. frumenti, are representative strains within the L. reuteri subgroup of lactobacilli with well-known probiotic properties 46 . L. taiwanensis has regulatory functions and interacts with dendritic cells of the lamina propria, as part of the bacterial-GALT crosstalk that maintains mucosal homeostasis 47 and these effects are consistent with the increased expression of the dendritic cell marker integrin α E observed in the present study. Mice exposed to L. taiwanensis show increased frequency of Treg cells in both mesenteric lymph nodes and Peyer's patches 48 , that then reside in the gut, where they expand and produce a tolerant environment for specific antigens 49 .…”

Specific Commensal Bacterium Critically Regulates Gut Microbiota Osteoimmunomodulatory Actions During Normal Postpubertal Skeletal Growth and Maturation

“…It has been well-established that SFB induces T H 17/IL17Amediated immunity in the lamina propria of the small intestine. (21,(28)(29)(30) SFB has also been shown to play a part in regulating macrophages, (58,104) DCs, (29,105,106) and effector T H 1 polarization. (21,35,104,107) Specifically, SFB utilizes intestinal phagocytes such as macrophages and DCs that are vital for commensal antigen-specific responses and T H 17 induction.…”

“…(21,(28)(29)(30) SFB has also been shown to play a part in regulating macrophages, (58,104) DCs, (29,105,106) and effector T H 1 polarization. (21,35,104,107) Specifically, SFB utilizes intestinal phagocytes such as macrophages and DCs that are vital for commensal antigen-specific responses and T H 17 induction. (58,105) Although secondary lymphoid tissues have been considered expendable in SFB-induced T H 17 cell maturation, (29,62) these tissues are still required to promote T H 17 specificity to SFB-derived antigens.…”

The Peyer’s Patch Mononuclear Phagocyte System at Steady State and during Infection

“…Thus, it is tempting to speculate that microbiota members capable of inducing strong humoral immune responses are those that strongly interact with the FAE. Once translocated in the SED, SFBs are internalized by CD11c int CD11b + and CD11c hi CD11b + phagocytes ( 82 ). Other IgA-inducer commensals, especially Alcaligenes species, reside inside CD11c + cells within isolated lymphoid follicles, PP, and mesenteric lymph nodes (MLN) of mice and humans ( 79 , 80 , 83 ).…”