Host adaptive immunity alters gut microbiota

Abstract

It has long been recognized that the mammalian gut microbiota has a role in the development and activation of the host immune system. Much less is known on how host immunity regulates the gut microbiota. Here we investigated the role of adaptive immunity on the mouse distal gut microbial composition by sequencing 16 S rRNA genes from microbiota of immunodeficient Rag1 À / À mice, versus wild-type mice, under the same housing environment. To detect possible interactions among immunological status, age and variability from anatomical sites, we analyzed samples from the cecum, colon, colonic mucus and feces before and after weaning. High-throughput sequencing showed that Firmicutes, Bacteroidetes and Verrucomicrobia dominated mouse gut bacterial communities. Rag1 À mice had a distinct microbiota that was phylogenetically different from wildtype mice. In particular, the bacterium Akkermansia muciniphila was highly enriched in Rag1 À / À mice compared with the wild type. This enrichment was suppressed when Rag1 À / À mice received bone marrows from wild-type mice. The microbial community diversity increased with age, albeit the magnitude depended on Rag1 status. In addition, Rag1 À / À mice had a higher gain in microbiota richness and evenness with increase in age compared with wild-type mice, possibly due to the lack of pressure from the adaptive immune system. Our results suggest that adaptive immunity has a pervasive role in regulating gut microbiota's composition and diversity.

Immunization with a heat-killed preparation of the environmental bacterium Mycobacterium vaccae promotes stress resilience in mice

“…Based on analysis of all samples across all time points, α-diversity was higher and β-diversity was lower in M. vaccae-immunized mice compared with vehicle-immunized mice (Fig. S4 A-E) [LMM, α-diversity, M. vaccae, phylogenetic diversity, F (1, 26.9) = 5.9, P < 0.05; observed species, F (1, 31.1) = 5.4, P < 0.05; Shannon index, F (1, 37.0) = 11.8, P < 0.01; M. vaccae × CSC × day, phylogenetic diversity, F (16, 36.1) = 2.1, P < 0.05; observed species, F (16, 36.1) = 2.1, P < 0.05; Shannon index, F (16, 47.5) = 1.3, P = 0.27], indicating that M. vaccae immunization had a stabilizing effect on the gut microbiota throughout the study, consistent with recent studies demonstrating that host adaptive immunity modulates the gut microbiota (40). In line with these findings, multiple linear regression showed that 11% of the variation in the gut microbiota was explained by the histological damage score in the colon, reflecting intestinal immune activation.…”

Stress and the microbiome: linking glucocorticoids to bacterial community dynamics in wild red squirrels

“…These taxa-specific responses to perturbation by HPA axis activity could be due to attenuation of adaptive immunity, which, unlike innate immunity, is a non-general response [23,26]. Therefore, taxa suppressed by an adaptive immune response would be expected to increase in abundance following heightened HPA axis activity.…”

IL-33 regulates the IgA-microbiota axis to restrain IL-1α–dependent colitis and tumorigenesis

“…Intestinal IgA is one such immune component that preferentially targets colitogenic members of the microbiota, including SFB and A. muciniphila (34,39,41,56,57). Reciprocally, certain pathobionts can produce proteolytic enzymes that degrade intestinal IgA and thereby enhance colitis susceptibility (40).…”