Effect of protease inhibitor bortezomib on treatment of rheumatoid arthritis by affecting IL-33/ST2 signaling pathway

AIM To investigate the effect of bortezomib， a protease inhibitor， on the treatment of rheumatoid arthritis （RA） and it mechanism， based on interleukin-33 （IL-33）/suppression of tumorigenicity 2 （ST2） signaling pathway. METHODS A total of 40 Wistar rats were randomly divided into 4 groups： control group， model group， and low- and high-dose bortezomib groups， with 10 rats in each group. In addition to control group， the rats in other groups were used to construct RA model. Bortezomib was given intraperitoneally at 0.2 mg/kg and 0.5 mg/kg in low- and high-dose bortezomib groups， respectively， while the rats in control group and model group were injected with the same amount of saline， once a day for 21 d. The general situation of the rats in each group was observed， the swelling degree of the foot was calculated， and the inflammation score was evaluated. HE staining was used to observe the pathological changes of ankle joint. The automatic biochemical analyzer was used to detect blood hemoglobin content， the total number of platelets （PLT）， serum creatinine （SCr） level and blood urea nitrogen （BUN） level. The serum levels of IL-6， tumor necrosis factor-α （TNF-α）， IL-33 and ST2 were measured by ELISA. The protein expression of IL-33 and ST2 in ankle tissues of each group was determined by Western blot. RESULTS On the 7th， 14th and 21th days after modeling， compared with control group， the degree of paw swelling in model group was significantly increased （P<0.05）. Compared with model group， the swelling degree of paw in low- and high-dose groups was decreased （P<0.05）. At the end of administration， compared with control group， the synovial cells in model group were increased and in disorder， with a lot of inflammatory exudates in the articular cavity， and the inflammatory score， the levels of PLT， SCr and BUN， the serum levels of IL-6， TNF-α， IL-33 and ST2， and the protein expression of IL-33 and ST2 in ankle tissues were significantly increased （P<0.05）. Compared with model group， the inflammatory exudates in the articular cavity of the rats in low- and high-dose bortezomib groups were decreased， and the inflammatory score， the levels of PLT， SCr and BUN， the serum levels of IL-6， TNF-α， IL-33 and ST2， and the protein expression of IL-33 and ST2 in ankle tissues were decreased （P<0.05）. CONCLUSION Bortezomib may reduce the inflammation and swelling of the joints in RA rats by regulating the IL-33/ST2 signaling pathway.