The Role of Heme Oxygenase 1 in Rheumatoid Arthritis and IL-1 Induced Inflammatory Cell Model.

Objective: Rheumatoid arthritis (RA) is a common chronic autoimmune inflammatory disease. The pathogenesis of RA is complex, and RA lacks effective therapeutic drugs. Heme oxygenase 1 (HO-1) is found to be reduced in RA. However, the role of HO-1 in RA and related mechanisms have not been elucidated.

Methods: RA rat model was established. The expression of HO-1 was upregulated by hemin. The increase weight rate, the degree of toe swelling, and the arthritis index were analyzed to evaluate the therapeutic effect of HO-1 on RA. In vitro RAW264.7 inflammatory cell model was established using 5 ng/mL IL-1. SnPP or hemin were used to inhibit or upregulate HO-1 expression. Tetrazolium salt colorimetric assay (MTT) was selected to test cell proliferation. ELISA was used to determine the concentrations of cellular inflammatory factors IL-1 and IL-6. Reactive oxygen species (ROS) activity was assessed. Western blot was performed to analyze NF-[Formula: see text]B and MMP-3 expressions.

Results: The expression of HO-1 was decreased in RA rats, and hemin increased HO-1 level in arthritic rats, which elevated the increase weight rate and decreased toe swelling degree and arthritis index (P<0.05). Hemin significantly upregulated HO-1 expression, inhibited inflammatory cell proliferation, decreased IL-1 and IL-6 expressions, declined ROS level, restrained NF-[Formula: see text]B expression, and enhanced MMP-3 expression in Raw264.7 cells induced by LPS (P<0.05). SnPP obviously inhibited the expression of HO-1, promoted cell proliferation, elevated IL-1 and IL-6 secretions, increased ROS level, promoted NF-[Formula: see text]B expression, and decreased MMP-3 level compared with LPS group (P<0.05).

Conclusion: Upregulation of HO-1 can improve arthritis symptoms by reducing ROS expression, inhibiting NF-[Formula: see text]B signaling pathway, elevating MMP-3 expression, attenuating inflammatory factor secretion, and suppressing inflammatory cell proliferation.