Increasing helminth infection burden depauperates the diversity of the gut microbiota and alters its composition in mice

Abstract

The gut microbiota constitutes a diverse community of organisms with pervasive effects on host homeostasis. The diversity and composition of the gut microbiota depend on both intrinsic (host genetics) and extrinsic (environmental) factors. Here, we investigated the reaction norms of fecal microbiota diversity and composition in three strains of mice infected with increasing doses of the gastrointestinal nematode Heligmosomoides polygyrus. We found that α-diversity (bacterial taxonomic unit richness) declined along the gradient of infective doses, and β-diversity (dissimilarity between the composition of the microbiota of uninfected and infected mice) increased as the infective dose increased. We did not find evidence for genotype by environment (host strain by infective dose) interactions, except when focusing on the relative abundance of the commonest bacterial families. A simulation approach also showed that significant genotype by environment interactions would have been hardly found even with much larger sample size. These results show that increasing parasite burden progressively depauperates microbiota diversity and contributes to rapidly change its composition, independently from the host genetic background.

Keywords: Dysbiosis; Genotype × environment interaction; Heligmosomoides polygyrus; Host genotype; Nematode.

Graphical abstract

Fig. 1

Reaction norms of OTU richness (A) and dissimilarity (Bray-Curtis distances) (B) of the fecal microbiota in three strains of mice infected with an increasing number of Heligmosomoides polygyrus larvae. We report the dissimilarity between the composition of the microbiota of uninfected and infected (200, 400 and 600 H. polygyrus larvae) mice. The values for 0 larvae refer to the inter-individual dissimilarity in the microbiota of uninfected mice. We report means ± standard errors. Dotted lines refer to the fit of the linear mixed effects models.

Fig. 2

Changes in relative abundance of the five commonest bacterial families, and Lactobacillaceae, across infective doses (number of Heligmosomoides polygyrus larvae) in three mouse strains. We report means ± standard errors. Dotted lines refer to the fit of the linear mixed effects models.