Toll-like receptors 4 contribute to endothelial injury and inflammation in hemorrhagic shock in mice

Objective Hemorrhagic shock followed by resuscitation (HS/R) promotes organ injury by priming cells of the innate immune system for inflammatory response. Toll-like receptors (TLRs) play an important role in signal transduction in shock/resuscitation conditions. Because proinflammatory mediators are a critical event in mesenteric endothelial injury induced by HS/R, we assessed the role of TLR4 or TLR2 in this setting. Design Laboratory investigation. Setting Research laboratory at Rouen University Medical School. Subjects Male wild-type, TLR4(-/-) and TLR2(-/-) mice with the same C57BL/6 background. Interventions Mice were submitted to 30 minutes hemorrhagic shock followed by 1 hour resuscitation, after which mesenteric endothelial dysfunction, microvascular injury, and TNF[alpha] production were assessed. Measurements and main results HS/R markedly decreased nitric oxide-mediated mesenteric relaxations induced by acetylcholine, assessed ex vivo on a myograph. By contrast, in TLR4-deficient mice, HS/R did not impair the nitric oxide-mediated responses to acetylcholine. No protection was observed in TLR2-deficient mice. TLR4-deficient mice also displayed a significant reduction in fluid resuscitation and TNF[alpha] systemic production. Conclusions TLR4 contributes to mesenteric endothelial dysfunction after hemorrhagic shock. This early TLR4-induced vascular injury may be an important trigger of the systemic inflammatory response occurring in this disease.