Crocetin inhibits leukocyte adherence to vascular endothelial cells induced by AGEs

Advance glycation end products (AGEs) have been postulated to play an important role in diabetic complications such as atherosclerosis disease. Adhesion and migration of leukocyte to endothelial cells (EC) is one of the early key steps in the pathogenesis. Crocetin is an important ingredient of diet in India and also used in various systems of indigenous medicine. In this study, we investigated effect of crocetin on leukocyte adherence to bovine endothelial cells (BEC) induced by AGEs in vitro and the possible mechanisms involved. BEC were pre-incubated with crocetin (0.01, 0.1, and 1 μM) for 12 h and exposed to AGEs (100 μg/ml). Cells proliferation was determined by MTT; leukocyte–endothelial cell adhesion was assayed by myeloperoxidase methods; intercellular adhesion molecular-1 (ICAM-1) protein expression was studied by immunocytochemistry and mitochondrial membrane potential (MMP) was analyzed by the retention of rhodamine 123 (RH123); furthermore, levels of anion (O2−), malonicdialdehyde (MDA) in super cells culture and superoxide dismutase (SOD) in cells were also detected, respectively. Results demonstrated that crocetin could inhibit AGE-induced BEC growth suppression and significantly reduce adhesion rate of leukocyte to BEC (P < 0.01 or P < 0.05); ICAM-1 protein was also suppressed (P < 0.05). Furthermore, crocetin could increase activity of SOD (P < 0.05), decrease levels of MDA and O2− (P < 0.01). In addition, down-regulated MMP was also increased by crocetin (P < 0.01 or P < 0.05). These data revealed crocetin could prevent the adhesion of leukocyte to BEC and down-regulation the expression of ICAM-1, and the possible mechanisms might be related to its antioxidant activity, which is through up-regulation of the activity of antioxidant enzymes and protection for mitochondrion.