The gut microbiota of toll‐like receptor 2‐deficient mice exhibits lineage‐specific modifications

Abstract

Mutations in toll-like receptors that mediate bacterial recognition by the mammalian innate immune system have the potential to substantially alter the composition of an individual's microbiota. Here we tested this hypothesis by comparing the intestinal microbiota of toll-like receptor 2-deficient mice, both young and middle aged, with that of wild-type mice of the same genetic background, housed together under specific pathogen-free conditions. Bacterial DNA was extracted from mouse caecal tissue samples, amplified using universal bacterial 16S ribosomal RNA gene primers, and cloned into a plasmid vector. Insert-containing colonies were picked for high-throughput sequencing, and sequence data were analysed yielding species-level phylogenetic data. Clone libraries were compared by phylogenetic composition analysis using UniFrac. While pairwise differences in phylogenetic population structure between mutant and wild-type mice were not statistically significant, anosim analysis did demonstrate a significant difference between toll-like receptor 2-deficient mice and their wild-type counterparts. The difference observed was probably due to a high level of colonization of the toll-like receptor 2-deficient mice by two distinct Helicobacter phylotypes that were totally absent from wild-type mice. Principal coordinate analysis clustering indicated that age is a weaker determinate than genotype and maternal heritage in the mouse caecal microbiota. The findings suggest that although mutations in toll-like receptors may cause increased susceptibility to specific opportunistic bacteria, they do not dramatically alter the phylogenetic structure of microbiota.

Temporal stability of the mouse gut microbiota in relation to innate and adaptive immunity

“…By contrast, the gut environments of immunodeficient mouse lines appear to select for a narrower range of core bacterial members. The absence of CD45, for instance, positively influences Toll-like receptor 2-and 9-mediated pro-inflammatory cytokine production (Cross et al, 2008), an exacerbation of the innate immune response that can lead to enhanced clearance of opportunistic, transient bacteria (Loh et al, 2008;Albert et al, 2009). While we show no aberrant expansion of populations such as segmented filamentous bacteria in any of our knock-out strains, other mouse lines with IgA deficiency have been noted to support abnormally high levels of specific intestinal anaerobic groups (Jiang et al, 2001;Suzuki et al, 2004).…”

Inflammation-associated enterotypes, host genotype, cage and inter-individual effects drive gut microbiota variation in common laboratory mice

“…Such models can be used to investigate the effects of food and drug uptake or the interplay between host and microbiota, demonstrating causality in disease and therefore the relevance of these model systems [34-37]. Knock-out and transgenic models have shown that host genes can influence the microbiota composition [38-41], have given insights into signaling cascades that mediate microbiome-host interactions [31,32,42,43] and enabled the study of the interplay between host physiology and microbiota composition [44-46]. …”

Can Colonoscopy Aspirates be a Substitute for Fecal Samples in Analyses of the Intestinal Microbiota?

“…It has been shown, in both humans and rodents, that the composition of tissue-associated microbiota is different than that of the fecal microbiota [22, 23]. The degree to which aspirates resemble the fecal or tissue-adherent microbiota is likely to depend on the bowel preparation type.…”