(150d) Identifying Novel Bacterial Proteases Involved In Enhanced Virulence During Chronic Infection

Host protease-antiprotease balance has emerged as a major factor in regulating the extent of inflammatory response by neutrophils, macrophages and endothelial cells to bacterial infections. In response to pro-inflammatory cytokines, activated neutrophils release a series of extracellular proteases, including cathepsins, MMPs and neutrophil elastase (NE), all of which exhibit strong elastolytic activity, the largest percentage of which is attributed to cathepsins. Activated cathepsins are inhibited by cystatins, and dysregulation of the cathepsin-cystatin balance has been strongly linked to chronic bronchial inflammation during P. aeruginosa infection, especially in cystic fibrosis (CF) patients. We recently identified a family of conserved bacterial peptidases present in several obligate pathogens, including P. aeruginosa, that we believe play a critical role in disturbing the cystatin-cathepsin balance during chronic infection. We plan to investigate peptidase expression levels from clinical isolates to correlate expression with severity of chronic infections, and utilize a novel chemical biology approach to design peptide-based inhibitors of protease function as a potential therapeutic and diagnostic for P. aeruginosa infection. Our work will advance the understanding of how chronic inflammation in the endobronchial space, exacerbated by the dominant neutrophil inflammatory response, can lead to host-induced tissue damage caused by pathogens such as P. aeruginosa.