Infections by human gastrointestinal helminths are associated with changes in faecal microbiota diversity and composition

Abstract

Investigations of the impact that patent infections by soil-transmitted gastrointestinal nematode parasites exert on the composition of the host gut commensal flora are attracting growing interest by the scientific community. However, information collected to date varies across experiments, and further studies are needed to identify consistent relationships between parasites and commensal microbial species. Here, we explore the qualitative and quantitative differences between the microbial community profiles of cohorts of human volunteers from Sri Lanka with patent infection by one or more parasitic nematode species (H+), as well as that of uninfected subjects (H-) and of volunteers who had been subjected to regular prophylactic anthelmintic treatment (Ht). High-throughput sequencing of the bacterial 16S rRNA gene, followed by bioinformatics and biostatistical analyses of sequence data revealed no significant differences in alpha diversity (Shannon) and richness between groups (P = 0.65, P = 0.13 respectively); however, beta diversity was significantly increased in H+ and Ht when individually compared to H-volunteers (P = 0.04). Among others, bacteria of the families Verrucomicrobiaceae and Enterobacteriaceae showed a trend towards increased abundance in H+, whereas the Leuconostocaceae and Bacteroidaceae showed a relative increase in H- and Ht respectively. Our findings add valuable knowledge to the vast, and yet little explored, research field of parasite—microbiota interactions and will provide a basis for the elucidation of the role such interactions play in pathogenic and immune-modulatory properties of parasitic nematodes in both human and animal hosts.

Residual feed intake divergence during the preweaning period is associated with unique hindgut microbiome and metabolome profiles in neonatal Holstein heifer calves

“…Biotin is an important cofactor for metabolic reactions such as glucose, amino acid and fatty acid metabolism [54]. Biotin also regulates important functions such as cell signaling and mucosal immune responses [55]. Through the upregulation of onecarbon metabolism, neurotransmitter biosynthesis (dopamine and serotonin) and oxidative stress reduction [56,57], greater production of vitamin B 6 and folate (vitamin B 9 ) could become key cofactors for regulation of cellular metabolism [58,59].…”

Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

“…In the murine gut, wound environment induces rapid changes in resident microbiota such as changes in microbial alpha or beta diversity [47]. Several intestinal nematodes such as N. brasiliensis, Trichuris trichiura or Ascaris lumbricoides induce significant alterations in diversity and composition of the intestinal microbiota [48][49][50][51]. Moreover, changes in microbial composition associated with parasite infections elicit upregulation of cytokines altering the regulation of the immune response [52][53][54].…”

“…To normalize for differences in efficiency of sample extraction or cDNA synthesis we used β-actin as housekeeping gene. To estimate the influence of infection in the expression levels we used a comparative quantification method (2 -ΔΔCTmethod) 51 . This method is based on the fact that the difference in threshold cycles (ΔCt) between the gene of interest and the housekeeping gene is proportional to the relative expression level of the gene of interest.…”

The interplay of type 2 immunity, helminth infection and the microbiota in regulating metabolism

“… Recent evidence showed that these products could have a direct inhibitory effect on bacteria growth (Figure ) . Whilst most data demonstrating the ability of helminths to alter the intestinal microbiota have been acquired through studies in rodents, evidence in humans also exists indicating this is likely to occur across multiple parasitic and host species …”

“…79 Whilst most data demonstrating the ability of helminths to alter the intestinal microbiota have been acquired through studies in rodents, evidence in humans also exists indicating this is likely to occur across multiple parasitic and host species. [80][81][82] Helminth-induced alterations to microbial communities have important functional consequences for the host as demonstrated in a recent study from our own group that showed that H. polygyrus infection provides protection against asthma by modulating the intestinal microbiota to increase the availability of short-chain fatty acids (SCFA). 80 SCFAs are a group of bacterial metabolites produced during the fermentation of fibre or mucus.…”