Reactive oxygen species (ROS) are involved in the shear-induced ICAM-1 expression in endothelial cells

ROS have been suggested to act as intracellular second messengers. The role of ROS in the shear flow-induced gene expression was examined by subjecting ECs to a shear force using a parallel-plate flow chamber system. ECs under shear flow increased their intracellular ROS as indicated by Superoxide production. This ROS production was maintained at an elevated level as shear flow remained. Sheared ECs, similar to the oxidant-treated cells increased their intercellular adhesion molecule-1 (ICAM-1) mRNA levels. Pretreatment of ECs with an antioxidant, NAC or catalase, inhibited this shear- or oxidant- induced ICAM-1 expression. Shear-induced promoter activities (-850bp) were attenuated by pretreating sheared ECs with antioxidant. Flow cytometric analysis and monocytic adhesion assay confirmed the inhibitory effect of antioxidant on the shear-induced ICAM-1 expression. These results indicate that shear flow to ECs induces intracellular ROS generation that results in an increase of ICAM-1 mRNA levels via transcriptional events. Our findings support the importance of intracellular ROS in modulating shear-induced endothelial responses, (supported by NSC, Taiwan, ROC).