Small interference RNA targeting TLR4 gene effectively attenuates pulmonary inflammation in a rat model

Abstract

Objective. The present study was to investigate the feasibility of adenovirus-mediated small interference RNA (siRNA) targeting Toll-like receptor 4 (TLR4) gene in ameliorating lipopolysaccharide- (LPS-) induced acute lung injury (ALI). Methods. In vitro, alveolar macrophages (AMs) were treated with Ad-siTLR4 and Ad-EFGP, respectively, for 12h, 24h, and 48h, and then with LPS (100ng/mL) for 2h, and the function and expression of TLR4 were evaluated. In vivo, rats received intratracheal injection of 300L of normal saline (control group), 300L of Ad-EGFP (Ad-EGFP group), or 300L of Ad-siTLR4 (Ad-siTLR4 group) and then were intravenously treated with LPS (50mg/kg) to induce ALI. Results. Ad-siTLR4 treatment significantly reduced TLR4 expression and production of proinflammatory cytokines following LPS treatment both in vitro and in vivo. Significant alleviation of tissue edema, microvascular protein leakage, and neutrophil infiltration was observed in the AdsiTLR4-treated animals. Conclusion. TLR4 plays a critical role in LPS-induced ALI, and transfection of Ad-siTLR4 can effectively downregulate TLR4 expression in vitro and in vivo, accompanied by alleviation of LPS-induced lung injury. These findings suggest that TLR4 may serve as a potential target in the treatment of ALI and RNA interfering targeting TLR4 expression represents a therapeutic strategy. Copyright 2012 Feixiang Wu et al.