Rho kinase inhibition by fasudil suppresses lipopolysaccharide-induced apoptosis of rat pulmonary microvascular endothelial cells via JNK and p38 MAPK pathway

Apoptosis of microvascular endothelial cells plays a crucial role in the progression of various lung diseases and triggers microcirculatory disorder and organ dysfunction. LPS, an outer membrane component of Gram-negative bacteria, is one of the major virulence factors for lung diseases. Recent studies have shown that the Rho/Rho kinase (ROCK) pathway plays an important role in the regulation of apoptosis, inflammatory cell migration and chemokine production in various cell types and animal models. We therefore undertake this study to investigate the inhibitory effect of fasudil, a potent and selective inhibitor of ROCK, on LPS-induced apoptosis of rat pulmonary microvascular endothelial cells (PMVECs). The results suggested that fasudil effectively prevented LPS-induced injury of rat PMVECs, as determined by MTT assay, LDH activity assay, apoptosis and western blot analysis of apoptosis-related proteins Bcl-2 and Bax. Furthermore, the mechanisms underlying the protective effect were evaluated. We found that LPS-induced MYPT-1 phosphorylation was markedly suppressed by fasudil. Moreover, fasudil pretreatment obviously inhibited the activation of JNK and p38 MAPKs induced by LPS, whereas that of ERK1/2 was not affected by fasudil. In addition, inhibiting the JNK and p38 pathways by SP600125 and SB203580 respectively attenuated the LPS-induced apoptosis and regulated the expression of apoptosis-related proteins Bcl-2 and Bax. Taken together, these results demonstrate that fasudil exerts an anti-apoptotic effect in rat PMVECs, which is mediated by the inhibition of Rho/ROCK and its downstream JNK and p38 MAPKs.