Communication in the Human Microbiota

Bacteria communicate not only with each other, but also with host cells, and this can modulate their growth, biofilm formation and virulence. In this field of UR CBSA research, the impact of endogenous molecules (hormones or neurotransmitters) and exogenous molecules (NOx, cosmetics, endocrine disruptors) as well as probiotics is assessed on bacteria representative of the cutaneous, respiratory and intestinal microbiota.

At the level of the skin and its appendages, this work is part of the concept of Cutaneous Bacterial Endocrinology, which aims to integrate all signals exchanged between the skin or mucous membranes (Substance P, CGRP, catecholamines, natriuretic peptides, estradiol...) and the associated microbiota. At the same time, we are studying the impact on this microbiota of atmospheric pollutants (NOx) and cosmetic active ingredients or preservatives, as well as nanoparticles present in the environment.

This work has a wide societal impact, particularly in the cosmetics industry. In the pulmonary field, we are particularly interested in bacteria of the genus Pseudomonas and Staphylococcus, which represent a major health risk, especially in the context of cystic fibrosis.

We have shown that natriuretic peptides, neurohormones, are capable of modifying the physiology of Pseudomonas aeruginosa, and in particular of destabilizing the biofilms formed by this pathogen. This work has led to a world patent currently being exploited.

The intestinal microbiota is also sensitive to neuroendocrine factors (Serotonin, Substance P, Epinephrine) and to the effect of probiotic strains, which can modulate the microbiota's response to pathogenic species (Enterococcus faecalis, P. aeruginosa) as well as the barrier properties of the intestinal epithelium.

These different aspects of communication between the human host and its microbiota are addressed in terms of population variation using high-throughput DNA sequencing techniques, as well as biofilm formation, or virulence expression using Omics studies and in vitro eukaryotic cell and tissue models. Particular attention is paid to the study of interactions between microorganisms of different species within the same microbiota.