Role of gut proteases in Yersinia infection in mice

• Applicant: Privatdozent Dr. Konrad Trülzsch
• Subject Area: Parasitology and Biology of Tropical Infectious Disease Pathogens
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 64038369

Yersinia enterocolitica is a common cause of food borne gastrointestinal disease leading to self limiting diarrhea and mesenteric lymphadenitis. Occasionally focal abscess formation in liver and spleen is observed in certain predisposed patients (e.g. hemochromatosis). In the oral mouse infection model yersiniae produce a similar disease forming monoclonal microabscesses in Peyer´s patches liver and spleen. Yersiniae invade Peyer´s patches (PP) of the distal ileum by binding to β1 integrins located on the apical surface of M cells overlying follicle associated lymphoid tissue. This is accomplished by the surface located invasin (Inv) protein and possibly by the Yersinia adhesin A (YadA). Invasin directly binds β1 integrins, whereas YadA binds β1 integrins indirectly by ECM bridging. We have recently shown that only very few yersiniae invade Peyer´s patches from the gut lumen (clonal invasion). This is due to both Yersinia and host specific factors. Invasin is rapidly degraded in vivo by gut proteases within 2 to 3 hours after oral infection of mice and is subsequently not expressed in the gut lumen. This presumably limits early (invasin dependent) invasion of Peyer´s patches to a few hours contributing to clonal invasion. In vivo proteolytic degradation is probably due to proteolysis by several gut proteases such as trypsin, chymotrypsin, pancreatic elastase, and pepsin. There are no reports on the actions of gut proteases on virulence factors of enteric pathogens (in contrast to viral pathogens such as reovirus that is activated by gut proteases). We will therefore study the interaction of Yersinia virulence factors and adhesins with gut proteases in vivo. We will identify protease cleavage sites in Inv and YadA. Furthermore we will study the relevance of protease attack on the invasion of yersiniae in cell culture and the mouse infection model. Inactivation of invasin by gut proteases could protect the host from hyperinvasion by Yersinia. On the other hand proteolysis of invasins and adhesins could promote bacterial spreading to new hosts by increasing shedding of yersinaie in feces.

• DFG Programme: Research Grants