Moxibustion intervention improves synovitis by down-regulating NLRP3/Caspase-1/IL-1β signaling of synovial tissue in rats with adjuvant arthritis.

Abstract

To observe the effect of moxibustion on activities of NOD-like receptor family protein 3 (NLRP3)/cysteine aspartic acid specific protease-1 (Caspase-1)/interleukin-1β (IL-1β) signaling pathway in rats with adjuvant arthritis (AA), so as to explore its mechanisms underlying improvement of rheumatoid arthritis (RA). Me-thods Thirty male Wistar rats were randomly divided into normal control, AA model and moxibustion groups, with 10 rats in each group. The AA model was replicated by raising in wind, cold and damp environment combined with complete Freund's adjuvant injection. In the moxibustion group, moxibustion was applied to bilateral "Shenshu" (BL23) and "Zusanli"(ST36) for 20 min each time, once daily for 21 days. Changes of joint swelling degree (JSD) and arthritis index (AI) in each group were observed. The ultrastructural changes of synovial cells in each group were observed by transmission electron microscopy. The protein expression levels of NLRP3, apoptosis-associated speck-like protein (ASC), Caspase-1, tumor necrosis factor-α (TNF-α) and IL-1β in the synovial tissues of the knee joint were measured by Western blot. Compared with the normal control group, JSD, AI and the protein expressions of NLRP3, ASC, Caspase-1, TNF-α and IL-1β in the synovial tissues were significantly increased (P<0.01) in the model group. In comparison with the model group, JSD, AI and the protein expression levels of NLRP3, ASC, Caspase-1, TNF-α and IL-1β were significantly decreased (P<0.01) in the moxibustion group. Results of transmission electron microscope showed an irregular and vague nuclear membrane of synovial cells, and unclear mitochondrial membrane boundary with sparse, swelling crests in the model group, which was relatively milder in the damage degree in the moxibustion group. Moxibustion can relieve the inflammatory response in the synovial membrane of AA rats, which may be related to its function in down-regulating synovial NLRP3/Caspase-1/IL-1β inflammatory signaling.