Frontier Leaders: Pathogens and commensals at mucosal surfaces: the Yin and yang of innate immunity

ITQB PhD Program Seminar Series

Frontier Leaders of Today for the Scientists of Tomorrow

Title: "Pathogens and commensals at mucosal surfaces: the Yin and yang of innate immunity"

Speaker: Philipe Sansonetti

Affiliation: Professeur au Collège de France, Professeur à l’Institut PasteurInstitut Pasteur, FR

Abstract:

Our immune system has likely evolved under the double constraint to tolerate the commensal microbiota, particularly in the gut, where bacteria can reach the astronomic numbers of 1014, belonging possibly to more than 10 000 species, most of them non cultivable, and conversely to quickly recognize and eliminate the pathogenic bacteria that reach and colonize this same surface. The cross talks that allow the host to discriminate between  the « good » microbes and the « bad » microbes are just starting to be recognized. This is not an easy task because both types of bacteria do express motifs (i.e. PAMPs) that are generally similar (i.e. LPS, peptidoglycan, flagellin, etc…). The discriminative process may therefore bear on other elements which, on the bacterial side, largely correspond to pathogenic factors and the corresponding signals they elicit, mostly proinflammatory and death signals. These signals get integrated into the more global concept of danger sensing. Shigella will be taken as a model sustem to define, via its well studied pathogenic factors, this concept of danger-mediated signaling by pathogens, compared to commensals.

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