Maintenance of Paraoxonase 2 Activity as a Strategy to Attenuate P. Aeruginosa Virulence
Annual rept. 30 Sep 2013-29 Sep 2014
TEXAS UNIV AT DALLAS SOUTHWESTERN MEDICAL CENTER
Pagination or Media Count:
The P. aeruginosa signaling and virulence molecule 3OC12 mediates inactivation of the lactonase paraoxonase 2 PON2 and induces many immunomodulatory effects in host cells. Because PON2 rapidly inactivates 3OC12, we hypothesized that preventing PON2 inactivation by 3OC12 could be a therapeutic strategy to limit P. aeruginosa quorum signaling and thereby attenuate virulence. In human and mouse primary cell types we found PON2 to be sensitive to 3OC12-mediated inactivation at concentrations of 3OC12 expected to be present near P. aeruginosa colonies during infection. We also discovered that 3OC12 is rapidly hydrolyzed intracellularly by PON2 to 3OC12-acid, which becomes trapped and accumulates within the cells, specifically within the endoplasmic reticulum and mitochondria. 3OC12 caused a rapid PON2-dependent cytosolic and mitochondrial pH decrease, calcium release and phosphorylation of stress signaling kinases. The findings suggest that intracellular acidification is the proximal event that mediates many immunomodulatory effects of 3OC12 and PON2 inactivation. PON2 appears to be inactivated by 3OC12 via an endoplasmic reticulum stress like response triggered by acidification. Two compounds were identified that inhibit both intracellular acidification and PON2 inactivation, suggesting that they could be developed as potential drugs to prevent 3OC12-mediated biological effects. Protecting cells from 3OC12-mediated acidification could be an important therapeutic strategy to attenuate P. aeruginosa quorum signaling and virulence as well as host cell immunomodulation.
- Medicine and Medical Research