Effects of extracellular acidosis on pyroptosis of rat articular chondrocytes and its possible mechanisms / 中国药理学通报

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.

Effects of BAPTA-AM on acid-induced autophagy of rat articular chondrocytes and its possible mechanisms / 中国药理学通报

Aim To observe the effect of BAPTA-AM on extracellular acid-induced autophagy in rat articular chondrocytes and its possible mechanisms.Methods Rat articular chondrocytes were isolated from Sprague-Dawley rats and incubated with different pH medium. The states of autophagy were examined by acridine or-ange (AO ) staining .Moreover,the expressions of LC3 ,Beclin-1 ,ULK1 ,CaMKKβ,AMPK and mTOR were detected using Western blot or quantitative real-time PCR (qRT-PCR ). Intracellular calcium ([Ca2+]i )was analyzed by a Ca2+-imaging method. Results Compared with pH 6.0 group,BAPTA-AM could significantly decrease the activation of autophagyinduced by acid exposure,and the expressions of autophagy markers including LC3 Ⅱ,Beclin1 and ULK1were also decreased,accompanied with reduced acidinduced [Ca2 +]i influx,decreased proteins expressionof CaMKKβand phosphorylatedAMPK,and increasedphosphorylation of mTOR.Conclusion BAPTAAMcan significantly restrain acidinduced autophagy in ratarticular chondrocytes,the mechanism of which may beassociated with decreased Ca2 + influx.