Holm B. J.1, Sorobetea D.2, Kiilerich P.1, Ramayo Caldas Y.3, Jordi Estelle J.3, Ma T.1, Madsen L.1,4, Karsten Kristiansen K.1, Svensson-Frej M.2
1 Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
2 Immunology Section, Department of Experimental Medical Sciences, Medical Faculty, Lund University, Lund, Sweden.
3 UMR1313 Génétique Animale et Biologie Intégrative (GABI) Equipe Génétique Immunité Santé (GIS), INRA, Jouy-en-Josas, France.
4 National Institute of Nutrition and Seafood Research, Bergen, Norway.

The parasitic worm Trichuris muris is the murine-specific counterpart to the human pathogen Trichuris trichuria that infects approximately 500 million people globally. Given that T. muris larvae inhabit the same niche as the majority of the intestinal microbiota it is plausible that these organisms influence each other, which may subsequently impact on the intestinal microenvironment of the host. In the present study we have investigated the effect of chronic T. muris infection on the gut microbiota and immune response in mice.
C57BL/6 mice were either infected with a low dose of T. muris eggs by oral gavage or left uninfected. Colon content was sampled after 0, 13, 20, 27, 35 days of chronic infection corresponding to the larvae molting stages. Microbiota analysis was performed using 16S-rRNA gene-based sequencing of the V4 region.
T. muris infection induced clear changes in the microbiota by decreasing alpha- and gamma diversity, and increasing beta diversity. Multiple bacteria families were affected by the infection, most notably with a marked increase in the relative abundance of Lactobacillaceae, supporting a previously suggested mutualism between nematodes and Lactobacillaceae. In addition, chronic T. muris infection induced an early T helper cell type 1 (Th1) response and affected the balance between inflammatory and regulatory immune cells in the intestinal mucosa.
Taken together, our data demonstrate that chronic infection with the nematode T. muris results in a significantly altered intestinal microbiota. These findings are of importance and relevance given the high incidence of helminth infections worldwide and the current efforts to use parasitic nematodes to treat immune-associated diseases.

Keywords: Trichuris muris, Intestinal microenvironment, Lactobacillaceae, Probiotics, Chronic T. muris infection

Holm B.J., et al. (2016). Chronic trichuris muris infection dramatically alters the murine intestinal microbiota.  Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 98.). IPC2016

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