Host-microbe symbiosis in the gut: A two-sided story

May 3rd 2018
Versione stampabile

Venue: Edificio Povo 1, via Sommarive nr. 5, Povo (Tn) - Room A206
 At 2.00 p.m.

  • Simone Becattini - Memorial Sloan-Kettering Cancer Center - Dr. Eric Palmer Lab, New York, USA

The symbiosis between host and mucosal-resident microbial communities, the microbiota, is complex and encompasses signals released in both directions. Our studies aim at elucidating such intricate dialogue, through dissection of mechanisms by which microbes impact host physiology, and vice versa. It is well appreciated that the microbiota influences host health states by modulating the activity of immune cells, as well as by conferring protection against enteric pathogens. We have identified members of the order Clostridiales that can protect the host against infection with the foodborne pathogen Listeria monocytogenes. Following this observation, we have found that temporary depletion of commensal communities can be used to allow controlled expansion of Listeria-based vaccine vectors, thus promoting accumulation of antigen-specific CD8 T cells in the intestinal lamina propria. Dissecting the molecular pathways leading to such enhanced CD8 responses will provide useful information for the design of improved mucosal vaccines. How host immune responses influence intestinal bacteria is on the contrary largely unknown. We analyzed the transcriptional profile of commensal and pathogenic bacteria upon induction of an intestinal immune response in mice. We identified a complex transcriptional program activated shortly after initiation of the immune response that includes up-regulation of multiple stress-resistance factors and down-regulation of enzymes involved in carbohydrate utilization. Genes identified with this approach might represent exploitable targets to enhance pathogen clearance while increasing resistance of key commensals to prolonged inflammation.