Mast cells mediate Pseudomonas aeruginosa lipopolysaccharide-induced lung inflammation in rat.

Activated mast cells have been demonstrated to play a pivotal role in Pseudomonas aeruginosa lung infections. However, there is no report about the involvement of mast cells in P. aeruginosa lipopolysaccharide (LPS)-induced lung inflammation. This study aimed at evaluating the role of mast cells in P. aeruginosa LPS-induced lung inflammation in rats. Mast cells stabilization was carried out by intraperitoneal injections of cromolyn. Lung inflammation was induced by the intratracheal instillation of P. aeruginosa LPS (5 μg/kg bw) and inflammatory status was evaluated 4 h post-LPS instillation. We found that activated mast cells could constitute a pivotal source of several inflammatory cytokines, including TNF-α, IL-1β, and IL-6. These cells might regulate polymorphonuclear neutrophil (PMN) recruitment and be implicated in the alteration of alveolar-capillary permeability via the release of TNF-α and IL-1β. We also detected that activated mast cells could be involved in the alteration of the expression of two epithelial tight junction proteins (claudin-1 and occludin) during the acute phase of inflammation. Our results suggest that activated mast cells might play a critical role in P. aeruginosa LPS-induced lung inflammation. Therefore, mast cell stabilization may be a potential novel approach for the prevention and treatment of P. aeruginosa-induced lung infections.