Effects of simvastatin on the function of dendritic cells in patients with rheumatic arthritis

Abstract

The present study examined the functional profile of dendritic cells (DCs) in patients with rheumatoid arthritis (RA) and the effects of simvastatin on the function of DCs. A total of 40 patients who was recently diagnosed as having RA were equally assigned to two groups: the routine treatment group (group R) and the routine treatment plus simvastatin group (group R+S). Twenty healthy individuals served as control. The peripheral blood mononuclear cells (PBMCs) were isolated before and 4 weeks after the treatment and then cultured with interleukin-4 (IL-4) and granulocyte-macrophage colony stimulatory factor (GM-CSF) to prepare mature DCs. The expression of co-stimulating factor CD86 on the surface of DCs was assessed by flow cytometry. And the stimulating capacity of DCs was measured by mixed lymphocyte reaction (MLR). The contents of cytokines in culture supernatants of DCs in MLR were detected by ELISA. Blood lipids and high-sensitivity C-reactive protein (hs-CRP) were detected. The relationship between the expression of CD86 and the blood CRP level was also investigated. The results showed that, as compared with the control group, the CD86 expression and the level of cytokines secreted by DCs were significantly increased in RA patients and greater stimulating capacity of DCs in MLR was demonstrated in RA patients. T lymphocytes in MLR secreted higher levels of proinflammatory cytokines (IL-2, IL-17, TNF-α and INF-γ) and lower level of anti-inflammation cytokine (IL-10). The function of DCs was markedly weakened and the level of hs-CRP and low-density lipoprotein was substantially lowered in group R+S in comparison to group R. The CD86 expression was positively correlated with hs-CRP. It was concluded that DCs in RA are highly activated and DC-initiated immune reaction may play an important role in the pathogenesis of RA. Simvastatin administration can significantly inhibit the DCs function and reduce the level of hs-CRP, indicating the suppression on inflammatory reaction may be one of the mechanisms by which simvastatin exerts its effect in treating RA.