[N-acetylcysteine inhibits the proliferation of hydrogen peroxide treated fibroblast-like synoviocytes in rats with adjuvant arthritis (AA) via blocking Nrf2/Keap1 pathway].

ABSTRACT

Objective To investigate the effect of N-acetylcysteine (NAC) on the proliferation of fibroblast-like synoviocytes (FLS) treated with low concentration of hydrogen peroxide (H2O2) in rats with adjuvant arthritis (AA) and its mechanism. Methods Twenty SD rats were divided into a normal group and a model group (10 rats in each group). The model group was established by subcutaneous injection of Freund's complete adjuvant into the toe of rats, and the rats were sacrificed 28 days later. The contents of serum malondialdehyde (MDA) were detected by thiobarbituric acid method; the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined by hydroxylamine method and colorimetry respectively; and Nrf2 and Keap1 proteins in ankle synovial tissues of AA rats were detected by immunohistochemistry. AA-FLS were isolated, cultured, and identified by digestion of ankle joint slides of AA rats in vitro. The effects of NAC at different concentrations (final concentration 0, 0.3, 0.9, 3, 10, 30, 90, 180 µmol/L) on the activity of AA-FLS treated with H2O2 at low concentration (5 µmol/L) were detected by CCK-8 assay. The content of mitochondrial reactive oxygen species (ROS) in AA-FLS was detected by MitoSOX fluorescent probe. The effects of NAC (final concentration 0, 3, 10, 30 µmol/L) on Nrf2 and Keap1 protein expressions in AA-FLS treated with H2O2 at low concentration were detected by Western blotting. Results Compared with those in the control group, in AA model, the MDA level increased and SOD and GSH-Px levels decreased in serum, and the Nrf2 protein increased and the Keap1 protein decreased in synovial tissue. Immunocytochemical staining confirmed that the isolated and cultured cells were AA-FLS; NAC inhibited the proliferation of AA-FLS treated with H2O2 in a concentration-dependent manner, and the mitochondrial ROS content and the protein expressions of Nrf2 and Keap1 decreased. Conclusion NAC can inhibit the proliferation of AA-FLS treated with H2O2, which may be related to blocking Nrf2/Keap1 pathway.