Mechanisms of P fimbriae cell activation

Microbial attachment to host cells plays a central role in the induction of inflammatory responses and the production of the disease. Uropathogenic Gram negative bacteria carry surface lectins that specifically recognize oligosaccharide receptor epitopes expressed on glycolipids or glycoproteins. The resulting attachment may facilitate the action of other virulence factors, but may also activate the receptor bearing cells directly to produce inflammatory mediators. These studies demonstrated that Escherichia coli fimbriae augment cytokine responses by the host urinary tract epithelium and that the receptor specificity of fimbriae determines the signaling pathways involved in these responses. P and type 1 fimbriae were shown to activate epithelial cytokine response via different signaling pathways. Furthermore, the type of fimbriae and their receptor specificity influenced the presentation of bacterial lipopolysaccharide to epithelial cells lacking CD14. These findings provide an example where the delivery mechanism itself determines the pathway of cell activation and where an additional microbial product may contribute if presented in the right molecular context