Amelioration of C-Reactive Protein and Lectin Like Oxidized Low Density Lipoprotein Receptor Complex Induced Endothelial Dysfunction by Oligomeric Proanthocyanidins

Abstract

C-reactive protein (CRP) is a well-established biochemical marker for atherosclerosis. Modification of LDL inside the artery wall favors the elevation of this acute phase protein. Hence, this mechanism is considered an important factor to trigger the monocyte to macrophages differentiation which results in the formation of foam cells. Therefore, this key event should be targeted and focused on how this complex (OxLDL + CRP) proceeds to endothelial dysfunction. Oligomeric proanthocyanidins (OPC) is a well-known cardioprotective flavon-3-ols. The present study is challenged between the cardioprotective roles of OPC against the deleterious effect of OxLDL + CRP complex upon endothelial cells. Protein-protein docking was carried out between CRP and LOX-1. This docked protein complex was again docked with OPC to show the inhibitory mechanism of CRP binding with LOX-1. OPC showed a promising inhibitory mechanism against OxLDL + CRP complex. Docking studies showed that in the absence of ligands (OPC), binding of CRP and LOX-1 was greater and vice versa in the presence of ligands. Based on these molecular docking results, in vitro studies have been carried out. The monolayer of endothelial cells was incubated with THP-1 monocytes for 48 h, induced with OxLDL (10 μg/ml) + CRP (15 μg/ml) and cotreated with OPC (100 μg/ml). Morphological changes, cell migration assay, and capillary tube forming assay were carried out. Myeloperoxidase levels were estimated to determine the adhesion of monocytes onto EC monolayer. RT-PCR analysis of L-Selectin was also done. The quantification of NO levels and analysis of mRNA expressions of eNOS was to determine the nitric oxide demand caused due to OxLDL + CRP complex. LOX-1, scavenger receptor levels were analyzed by mRNA expression. Proinflammatory markers such as IL-6, MCP-1, and IL-1β were studied. Accumulation of ROS levels was measured fluorimetrically using DCF-DA staining. Mitochondrial membrane potential was determined by JC-1 dye and cell cycle analysis was done by FACS analysis. To emphasis the results, the OPC-treated group showed decreased levels of proinflammatory markers, LOX-1 and L-selectin levels. Endothelial nitric oxide levels were increased upon OPC treatment and reduction in the ROS levels was also observed. Endothelial cells apoptosis was prevented by OPC. To conclude, OxLDL + CRP complex inhibitory effects of OPC could maintain the normal homeostasis.

Keywords: CRP; Endothelial dysfunction; Inflammation; OPC; OxLDL.