Next November 14 at 11 am it will take place the seminar "Mucosal Antibody Responses in Host-Microbiota Interaction and Gut Homeostasis"  by Giuliana Magri from  B cell biology group, IMIM Hospital del Mar Medical Research Institute, Barcelona

Abstract

A highly diverse community of microorganisms, generally referred to as microbiota, inhabits our bodies and influences a multitude of physiological processes, including host metabolism and immune system development. Microorganisms cover essentially all host mucosal surfaces, but most reside within the gastrointestinal tract. The gut microbiota cohabits with the host in a mutualistic relationship where both parties coexist peacefully and benefit from the other. Disruption of this homeostatic balance has been associated with obesity, malnutrition, inflammatory bowel diseases (IBD), autoimmunity and cancer.

The maintenance of intestinal homeostasis requires minimizing contact between potential pathogens and the host, restricting microbial overgrowth and selecting and diversifying beneficial microbial communities. One of the most important strategies adopted by the host immune system to maintain gut homeostasis is the secretion of antibodies, such as secretory IgA (and IgM), in the intestinal lumen. Secretory Igs (Sigs) originate from B cell-derived plasma cells located in the gastrointestinal tract and are the major antigen specific mechanisms by which the adaptive immune system can physically interact with the gut microbiota. It is estimated that the intestine alone receives 3 to 5 grams of SIgs every day, strongly supporting the biological significance of this system. IgA production is highly dependent on intestinal microbiota as mucosal IgA is nearly absent in germ free mice. After microbial colonization fecal IgA specific for gut microbes rapidly increase. Recent studies have also shown that gut IgA co-develops in parallel with the developing microbiota in the first 2 years of life, supporting the idea that SIgs can shape postnatal microbiota assembly.

In this lecture I will discuss recent advances in the characterization of the induction and regulation pathways for mucosal antibody production and the impact of mucosal antibodies in the regulation of host-microbiota interaction and gut homeostasis. I will also present some of our published and unpublished results on the ontogeny and function of intestinal secretory IgM and IgA in humans.