Catalpol Inhibits Homocysteine-induced Oxidation and Inflammation via Inhibiting Nox4/NF-κB and GRP78/PERK Pathways in Human Aorta Endothelial Cells

, ICAM-1, MCP-1, VCAM-1, IκB, nucleus p65, p65 phosphorylation, caspase-3, -9, bax, bcl-2, and ER stress-related proteins. (4) The expressions of CHOP, ATF4 were measured by qRT-PCR. (5) Mitochondrial membrane potential in HCY-treated HAECs was measured by rhodamine 123 staining, and the samples were observed by confocal laser scanning microscopy. 2. DPI, PDTC, and TUDCA were used to determine the interaction among Nox4/ROS, NF-κB, and endoplasmic reticulum stress. 3. TUDCA or Nox4 siRNA were used to investigate whether the effect of catalpol inhibiting the over-production of ROS were associated with inhibiting ER stress and Nox4 expression. Catalpol significantly suppressed LDH release, MDA level, and the reduction of GSH. Catalpol reduced HCY-stimulated ROS over-generation, inhibited the NF-κB transcriptional activation as well as the protein over-expressions of Nox4, ICAM-1, VCAM-1, and MCP-1. Catalpol elevated bcl-2 protein expression and reduced bax, caspase-3, -9 protein expressions in the HCY-treated HAECs. Simultaneously, catalpol could also inhibit the activation of ER stress-associated sensors GRP78, IRE1α, ATF6, P-PERK, P-eIF2α, CHOP, and ATF4 induced by HCY. In addition, the extent of catalpol inhibiting ROS over-generation and NF-κB signaling pathway was reduced after inhibiting Nox4 or ER stress with DPI or TUDCA. The inhibitor of NF-κB PDTC also reduced the effects of catalpol inhibiting the expressions of Nox4 and GRP78. Furthermore, the effect of catalpol inhibiting the over-generation of ROS was reduced by Nox4 siRNA. Catalpol could ameliorate HCY-induced oxidation, cells apoptosis and inflammation in HAECs possibly by inhibiting Nox4/NF-κB and ER stress.