Nadine Cerf-Bensussan, “Host-microbiota interactions across the gut immune system: an evolutionary trade-off”
Abstract
To cope with the complex microbial community that settles in the distal part of our intestine after birth, hosts have evolved a spectrum of complementary innate and adaptive immune mechanisms. This highly dynamic barrier is programmed ante-natally but fully develops only after birth in response to signals from the microbiota. To analyse the host-microbiota dialogue, we have chosen to address two main questions.
1- What are the respective roles of individual bacterium in driving the maturation of the gut barrier? Do they exert distinctive or redundant effects? Our studies in gnotobiotic mice have unexpectedly revealed that a restricted number of host-specific bacterial species, the prototype of which is Segmented Filamentous bacterium (SFB), are necessary for the complete maturation of the gut immune barrier. We will discuss how the ecological niche of SFB differs from that of other members of the microbiota, and enables SFB to deliver signals, which instruct the development of gut innate and adaptive immune responses and help establishing a state of physiological inflammation, which protects the host against pathogens.
2- What are the key mechanisms evolved by the hosts, to cope with the microbiota? Our current work led in children affected by monogenic disorders causing early onset intestinal inflammation provides interesting insight on conserved genetic mechanisms to maintain mutualistic relationships with the microbiota.
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