Homocysteine impaired endothelial function through compromised vascular endothelial growth factor/Akt/endothelial nitric oxide synthase signalling.

1. Hyperhomocysteinaemia (HHcy) is associated with endothelial dysfunction and has been recognized as a risk factor of cardiovascular disease. The present study aimed to investigate the effect of homocysteine (Hcy) on endothelial function in vivo and in vitro, and the underlying signalling pathways. 2. The HHcy animal model was established by intragastric administration with l-methionine in rats. Plasma Hcy and nitric oxide (NO) concentration were measured by fluorescence immunoassay or nitrate reductase method, respectively. Vasorelaxation in response to acetylcholine and sodium nitroprusside were carried out on aortic rings. Human umbilical vein endothelial cells (HUVEC) were treated with indicated concentrations of Hcy in the in vitro experiments. Intracellular NO level and NO concentration in culture medium were assayed. The alterations of possible signalling proteins were detected by western blot analysis. 3. l-methionine administration induced a significant increase in plasma Hcy and decrease in plasma NO. Endothelium-dependent relaxation of aortic rings in response to acetylcholine was impaired in l-methionine-administrated rats. The in vitro study showed that Hcy reduced both intracellular and culture medium NO levels. Furthermore, Hcy decreased phosphorylation of endothelial nitric oxide synthase (eNOS) at serine-1177 and phosphorylation of Akt at serine-473. Hcy-induced dephosphorylation of eNOS at Ser-1177 was partially reversed by insulin (Akt activator) and GF109203X (PKC inhibitor). Furthermore, Hcy reduced vascular endothelial growth factor (VEGF) expression in a dose-dependent manner. 4. In conclusion, Hcy impaired endothelial function through compromised VEGF/Akt/endothelial nitric oxide synthase signalling. These findings will be beneficial for further understanding the role of Hcy in cardiovascular disease.

Fasudil attenuates lipopolysaccharide-induced acute lung injury in mice through the Rho/Rho kinase pathway.

BACKGROUND: The transendothelial migration of polymorphonuclear leukocytes (PMNs, neutrophils) may be a hallmark of acute lung injury (ALI). The breakdown of the vascular endothelial barrier has likewise been considered to have etiologic linkage in the pathogenesis of ALI. Rho-associated coiled-coil-forming protein kinase (ROCK), a downstream target effector of the small GTP-binding protein Rho, plays a key role in cell adhesion, motility, and contraction mediated by reorganization of the actin cytoskeleton. The aims were to investigate protection by fasudil in lipopolysaccharide (LPS)-induced ALI and the role of ROCK2 in neutrophil transendothelial migration in a murine model. MATERIAL/METHODS: Mice were assigned to three groups: sham-treated controls (Sham group), LPS instillation (LPS group), and protective application of fasudil and LPS instillation (Fasudil/LPS group). Indexes tested were breathing frequency, histopathological examination, lung injury score, lung wet-to-dry weight ratio, neutrophil percentage in bronchoalveolar lavage fluid (BALF), myeloperoxidase activity, and ROCK2 mRNA expression in lung homogenate. RESULTS: Permeability pulmonary edema (histopathological examination, lung injury score, and lung wet-to-dry weight ratio) was ameliorated and neutrophil infiltration in the lungs (neutrophil percentage in BALF, myeloperoxidase activity) was depressed in response to fasudil administration. Expression of ROCK2 mRNA in the lung homogenates of the LPS-treated mice increased approximately fourfold; however, fasudil did not affect the increase. CONCLUSIONS: The Rho/Rho kinase pathway may play an important role in the pathogenesis of LPS-induced ALI and fasudil, as a ROCK inhibitor, could decrease neutrophil transendothelial migration by attenuating cytoskeletal rearrangement of endothelial cells, leading to the inhibition of ALI development.