Aim To study the effects of extracellular acidosis on articular chondrocytes pyroptosis and its possible mechanisms. Methods Primary articular chondrocytes were incubated in different pH and NAC. The expression of proinflammatory cytokines IL-1β, IL-18, ASC, NLRP3, caspase-1 were detected by Western blot and real-time PCR. The state of pyropto-sis was identified by AO/EB staining and LDH con-tents. The expression of ROS was observed by DCFH-DA, and ELISA was used to detect the IL-1β,IL-18 in cultured supernatants. Results Compared with the normal cell, extracellular acidosis could increase the expression of IL-1β, IL-18, ASC, NLRP3 and caspase-1 , upregulate the fluorescence intensity of in-tercellular ROS, accompanied with the promoted release of LDH. Moreover, it is observed that extra-cellular acidosis could also induce chondrocytes death by AO/EB staining. NAC,the scavenger of ROS could inhibit these effects of extracellular acidosis on chon-drocytes. Conclusion Extracellular acidosis may in-duce chondrocyte pyroptosis via upregulating the intra-cellular ROS content.

Objective: To investigate the effect of acid-sensing ion channel 1 (ASIC1) gene knockout on articular cartilage injury in adjuvant arthritis (AA) of mice． Methods: Wild-type mice and ASIC1 knockout mice were divided into normal group and model group．Arthritis score was performed by observing the inflammation of paws，and the right paw swelling was measured．HE staining，immunohistochemistry，TUNEL and ELISA were used to detect the injury of articular cartilage and arthritic inflammation. Results : The arthritis score and paw swelling of AA mice with ASIC1 knockout was lower than that of the AA wild-type mice．AA mice with ASIC1 knockout showed less destruction and increased expression of collagen-Ⅱin articular cartilage． Moreover ，the lower apoptosis rate was observed by TUNEL assay in AA mice with ASIC1 knockout by comparing with AA wild-type mice．Furthermore，ELISA assay showed that the levels of IL-1 β、TNF-α in the serum decreased in AA mice with ASIC1 knock- out． Conclusion Knockout of ASIC1 may have protective effect on articular cartilage injury.