Nrf2/ARE pathway inhibits inflammatory infiltration by macrophage in rats with autoimmune myositis

Background: Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterized by muscle disorders. We conducted this study to detect whether NF-E2-related factor 2 (Nrf2) pathway inhibit inflammatory infiltration by macrophage in experimental autoimmune myositis (EAM) rat model. Methods: CD163 levels were examined by immunohistochemistry (IHC), while serum creatine kinase (CK), reactive oxygen species (ROS), and serum monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) levels were determined by enzyme linked immunosorbnent assay (ELISA), both in IIM patients and EAM rat. We also detected MCP-1, TNF-alpha, IL-6, and Nrf2 levels by Realtime quantitative PCR (RT-PCR) in patients' muscles, and MCP-1, TNF-alpha, IL-6, and Nrf2, HO-1, NQO-1 levels by RT-PCR and Western blot in EAM rats' muscles. EAM macrophages were separated, and Nrf2 over-expression macrophages were constructed. ROS level and cell migration were detected by flow cytometer and transwell assay respectively. Then, levels of MCP-1, TNF-alpha, IL-6, Nrf2, Heme oxygenase-1 (HO-1) and NAD(P)H: quinine oxidoreductase 1 (NQO-1) were detected by RT-PCR and Western blot. Results: Results showed that EAM rats were histopathologically inflammatory cell infiltration. Levels of CD163, serum CK and ROS, serum/muscle MCP-1, TNF-alpha and IL-6 increased and muscle Nrf2 level decreased in IIM patients and EAM rats. Cell migration ability and levels of ROS, MCP-1, TNF-alpha, IL-6, and plasma Nrf2 were down-regulated, and total/nucleus Nrf2, HO-1, NQO-1 were up-regulated notably when Nrf2 over-expressed. Conclusion: Nrf2 inhibited EAM macrophage infiltration by activating Nrf2/ARE pathway which could induce ROS degradation and inhibit pro-inflammatory factors expression.