Alpha-tocopherol Attenuates the Severity of Pseudomonas aeruginosa-induced Pneumonia.

Pseudomonas aeruginosa is a lethal pathogen that causes high mortality and morbidity in immunocompromised and critically ill patients. The Type III secretion system (T3SS) of P. aeruginosa mediates many of the adverse effects of infection with this pathogen including increased lung permeability in a toll-like receptor 4/Rho A/plasminogen activator inhibitor (PAI)-1-dependent manner. Alpha-tocopherol has anti-inflammatory properties that may make it a useful adjunct in treatment of this moribund infection. We measured transendothelial and transepithelial resistance, Rho A and PAI-1 activation, stress fiber formation, P. aeruginosa T3SS exoenzyme (Exo Y) intoxication into host cells, and survival in a murine model of pneumonia in the presence of P. aeruginosa and pretreatment with alpha-tocopherol. We found that alpha-tocopherol alleviated P. aeruginosa-mediated alveolar endothelial and epithelial paracellular permeability by inhibiting RhoA, in part, via PAI-1 activation and increased survival in a mouse model of P. aeruginosa pneumonia. Furthermore, we found that alpha-tocopherol decreased the activation of RhoA and PAI-1 by blocking the injection of T3SS exoenzymes into alveolar epithelial cells. P. aeruginosa is becoming increasingly antibiotic-resistant. We provide evidence that alpha-tocopherol could be a useful therapeutic agent for individuals that are susceptible to infection with P. aeruginosa such as those who are immunocompromised or critically ill.