Abstract 17425: Curcumin Ameliorates Experimental Autoimmune Myocarditis by Inducing M2 Macrophage Polarization

Abstract

AIMS: Our previous study showed that curcumin, the main active ingredient in turmeric, induces the polarization of macrophages to anti-inflammatory M2 phenotype. In this study, we addressed the underlying mechanisms and observed whether curcumin exerts its protective effects on experimental autoimmune myocarditis (EAM) by facilitating the M2 phenotype polarization of macrophages. METHODS AND RESULTS: The mRNA and protein expression of M2 markers, including MMR, Arg-1, KLF-4 and PPAR-γ, were obviously up-regulated in curcumin-treated RAW264.7 macrophages. Curcumin increased not only IL-4 and IL-13 mRNA expression, but also protein content of these two cytokines in supernatant. The STAT6 inhibitor leflunomide antagonized the induction of MMR, Arg-1, KLF-4 and PPAR-γ by curcumin in RAW264.7 cells, which is suggested that curcumin induces macrophages M2 polarization through secretion of IL-4 and IL-13 in an autocrine manner. In vivo, 6-week-old male Lewis rats were immunized with myosin to induce EAM and orally administrated with curcumin (50mg/kg/day) or corn oil for 3 weeks after myosin injection. Cardiac functional parameters, including LVFS, EF, LVESD and HR, were significantly improved by curcumin treatment. Curcumin also reduced the heart weight-to-body weight ratio, inflammatory cell infiltration and the myocardial mRNA level of IL-1β and iNOS. Meanwhile, the myocardial mRNA level of KLF4, MMR and Arg-1 were markedly up-regulated by curcumin. Immunofluorescence assay showed that the number of CD68+MMR+ and CD68+Arg-1+ double positive macrophages in curcumin-treated myocardial tissue was obviously more than vehicle-treated ones. CONCLUSIONS: Taken together, these results show that curcumin ameliorates EAM by attenuating inflammation and by inducing macrophage M2 polarization.