Rho-kinase-dependent F-actin rearrangement is involved in the release of endothelial microparticles during IFN-α-induced endothelial cell apoptosis.

Abstract

Activation of cytoskeleton regulator Rho-kinase during inflammatory stimulations plays a major role in cellular dysfunction and apoptosis. Because endothelial dysfunction may be influenced by increased circulating membrane microparticles (MPs), we hypothesized that inhibition of Rho-kinase can prevent interferon-α (IFN-α)-induced endothelial cell (EC) apoptosis and that protective effects of Rho-kinase inhibition are facilitated by prevention of F-actin rearrangement. In this study, Lewis rats were subjected to an intraperitoneal injection of IFN-α or IFN-α + Y-27632. FCM was performed to analyze circulating endothelial MPs (EMPs) from the blood samples of these animals by detecting the expression of CD144, CD62E, CD31, CD51, and CD54 on EMPs. IFN-α-induced pulmonary injury was assessed by measurement of lung wet-to-dry weight ratios and measurement of alveolar wall thickness. Human pulmonary microvascular ECs (HPMECs) were cultured with IFN-α or EMPs to elucidate the probable mechanisms of the release of EMPs. Injection of IFN-α resulted in much higher levels of CD144 EMPs, CD62E EMPs, CD31 EMPs, CD51 EMPs, and CD54 EMPs. Pulmonary injury was also observed after injection of IFN-α. Furthermore, IFN-α induced F-actin rearrangement and apoptosis of HPMECs in vitro, and the Toll-like receptor 4/MyD88 and nuclear factor-κB pathways and EMPs per se played important roles in this process. The results demonstrate that increased Rho-kinase activity causes the release of EMPs and cellular apoptosis. Moreover, HPMEC apoptosis that resulted from EMP stimulation indicates that EMPs can be considered as a potential target to regulate the rearrangement of cytoskeleton during endothelial cell apoptosis.