Stretch Induced Apoptosis Of Chondrocytes Via The Pathway Of Reactive Oxygen Species Activated Endolplasmic Reticulum Stress

Objective:To investigate the expression and relationship between reactive oxygen species(ROS)and endoplasmic reticulum stress(ERS)in the process of stretch induced apoptosis of chondrocytes.Methods:The human articular chondrocytes was cultured and divided into groups that disposed with stretch 0h,2h,12 h,24h,respectively.And the groups disposed with stretch and antioxidant: N-acetyl cysteine as inhibitor group.The expressions of the caspase-12 were assessed by revers transcription-polymerase chain reaction(RT-PCR)and Western Blot.The expression of the Bax and Bcl-2 were also assessed by RT-PCR.The intracellular ROS were detected with DCFH-DA.Apoptosis was evaluated by flow cytometry.Results:The result of the RT-PCR had shown that the expression of the caspase-12 and Bax began to increase at 6h,and reached highest at 24 h,with significant difference(P < 0.05);however,the expression of the Bcl-2 began to decrease at 6h,and reached lowest at 12 h,it began to increase again at 24h;The result of the ROS began to increase at 6h,and reached highest at 24.The ROS,Bax and caspase12 in the NAC group was decreasing than stretch group(p<0.05);however the Bcl-2 in the NAC group was increase than stretch group(p<0.05);The result of the Western-Blot of casepase-12 was similarly with the result of RT-PCR.In the Z-ATAD-FMK group,the casepase-12 was decrease;however,The result of ROS was not changed.The result of the cell apoptotic in the stretch group was increased at 6h and reached highest at 24 h,However,compared with the stretch group,the cell apoptotic in the NAC group was lower obviously(p<0.05).Conclusion:The apoptosis of chondrocytes could be induced by stretch,and The ROS may be the superior signal that active ERS in this process.