Influence of oxidized low-density lipoprotein on siglec-1 expression and cytokine secretion by U937 cells / 第二军医大学学报

ABSTRACT

Objective:To explore the role of sialic acid-binding immunoglobulin-like lectin-one (Siglec-1) in oxidized lowdensity lipoprotein (ox-LDL)-induced atherosclerotic inflammation. Methods: Ox-LDL was prepared by oxidization of native LDL ;different concentrations of ox-LDL were used to treat U937 cells for 48 h. Cells and supernatants were collected. The expression of Siglec-1 protein and mRNA was examined by flow cytometry (FCM) and real-time quantitative RT-PCR, respectively. The levels of MIP-1α, MCP-I and IL-8 in the supernatants were determined by ELISA. Results: Stimulation with ox-LDL significantly increased Siglec-1 protein and mRNA in U937 cells compared with the control group ( P < 0. 01). Meanwhile, the levels of MIP-Iα, MCP-I and IL-8 in the supernatants were also significantly increased in a concentration-dependent manner compared with those in the control group(P<0. 01). Conclusion: The proatherogenic effect of ox-LDL may be partly through up-regulating Siglec-1 expression in macrophages and enhancing the expression of inflammatory cytokines and chemokines. The activated macrophages recruit more macrophages and lymphocytes to the site of atherosclerotic plaques and exacerbate the inflammatory responses.