Resveratrol ameliorates Serratia marcescens-induced acute pneumonia in rats

Serratia marcescens is an important nosocomial pathogen, which has been especially problematic as a cause of hospital-acquired pneumonia in the past two decades. Treatment of S. marcescens-related infections has been limited by emergence of multiple drug-resistant strains. Thus, the development of alternative agents for the prevention and treatment of Serratia infection is urgently needed. Resveratrol (RSV) is a compound with diverse biological effects including anti-cancer, anti-inflammation, anti-diabetes, and cancer chemoprevention. Whether RSV has in vivo prophylactic or therapeutic potential against infection remains uncharacterized. In the present study, we used a murine acute pneumonia model initiated by intratracheal application of S. marcescens to evaluate whether RSV possesses anti-infection properties. We showed that pretreatment with RSV for 3 days markedly increased alveolar macrophage infiltration, elevated NK cell activity, and decreased bacterial burden in the infected lung with a subsequent decrease in mortality. These effects were associated with significantly less-severe inflammatory phenotypes in lung tissue and bronchoalveolar lavage fluid, including reduced neutrophil infiltration of the lungs, reduced phagocytosis activity, and reduced secretion of cytokines such as TNF-alpha, IL-1beta, and IL-6. To further characterize the underlying mechanism responsible for these effects of RSV, LPS derived from S. marcescens was used to induce acute pneumonia in rats, with or without RSV pretreatment. RSV was shown to ameliorate acute pneumonia via inhibition of the NF-kappaB signaling pathway, including inhibition of IkappaBalpha phosphorylation and subsequent NF-kappaB activation. These findings suggest that RSV might be beneficial as a prophylactic treatment in patients at risk of an episode of S. marcescens-induced acute pneumonia.