This document summarizes research on the molecular mechanisms underlying inflammation caused by enteroaggregative Escherichia coli (EAEC) in the intestinal epithelium. EAEC causes chronic inflammation through the expression of aggregative adherence fimbriae (AAF) on its surface. In vitro studies showed that AAF expression triggers the basolateral release of the chemokine IL-8 from intestinal epithelial cells and the transmigration of polymorphonuclear neutrophils (PMNs). Further experiments identified that AAF expression from the prototype EAEC strains 042 and JM221, as well as the AAF/I and AAF/III fimbriae encoded on plasmids, are required for inducing PMN migration. Studies