Role of p38 MAP kinase in the development of acute lung injury

Acute lung injury (ALI) is characterized by an intense pulmonary inflammatory response, in which neutrophils play a central role. The p38 mitogen-activated protein kinase pathway is involved in the regulation of stress-induced cellular functions and appears to be important in modulating neutrophil activation, particularly in response to endotoxin. Although p38 has potent effects on neutrophil functions under in vitro conditions, there is relatively little information concerning the role of p38 in affecting neutrophil-driven inflammatory responses in vivo. To examine this issue, we treated mice with the p38 inhibitor SB203580 and then examined parameters of neutrophil activation and acute lung injury after hemorrhage or endotoxemia. Although p38 was activated in lung neutrophils after hemorrhage or endotoxemia, inhibition of p38 did not decrease neutrophil accumulation in the lungs or the development of lung edema under these conditions. Similarly, the increased production of proinflammatory cytokines and activation of NF-kappaB in lung neutrophils induced by hemorrhage or endotoxemia was not diminished by p38 inhibition. These results indicate that p38 does not have a central role in the development of ALI after either hemorrhage or endotoxemia.