Host Cell Killing by EPEC: Centeral Role in Pathogenesis

DESCRIPTION (provided by applicant): Enteropathogenic E. coli (EPEC) is a common cause of severe, watery diarrhea in children in developing countries. EPEC is also the prototype of a group of attaching and effacing intestinal pathogens, including enterohemorrhagic E. coli (EHEC, such as O157:H7), Citrobacter rodentium, Hafnia alvei, and EPEC-like E. coli strains of domestic animals. Unlike many other E. coli strains that cause diarrhea, EPEC produces no known toxins, so the way it causes disease has been puzzling. Despite major advances in understanding how EPEC adhere, trigger cytoskeletal rearrangements in the host, and cause other host cell alterations, the mechanism by which EPEC causes diarrhea has been unclear. The discovery that EPEC triggers host cell death provided an important lead in how EPEC causes disease. The mode of cell death triggered by EPEC has features of both apoptosis (programmed cell death) and necrosis. One of the non-apoptotic features of EPEC-mediated killing is release of adenosine triphosphate (ATP) from the host cell. Once released, ATP is broken down to other adenine nucleotides and adenosine. Adenosine itself acts as a potent secretatagogue, i.e., a stimulator of intestinal fluid and electrolyte secretion, which may cause or contribute to watery diarrhea. The present application seeks to understand how EPEC triggers the ATP release from the host, with a particular focus on the role of the cystic fibrosis transmembrane regulator (CFTR). Other goals include determining the signaling pathways activated by adenosine which activate intestinal secretion, and the determining the extent of release of adenine nucleotides into the intestinal tract of rabbits infected with the EPEC-like pathogens rabbit diarrheagenic E. coli (RDEC-1) and rabbit EPEC (REPEC).