GSDMD inhibitor protects chondrocyte from mechanical injury in human articular cartilage

Traumatic arthritis is caused by mechanical injury and results in the degeneration of articular cartilage, but it is unclear whether it is related to the pyroptosis of chondrocyte (CHs). Thus, this study was designed to investigate the role of GSDMD, the executor of pyroptosis, in the human cartilage during mechanical injury. We collected the human hip joint and used a loading apparatus to produce compression on the cartilage disc. After one hour of 15 MPa or 25 MPa injury, the acute and chronic effects of the mechanical injury on the cartilage were tested. We stained the CHs in the cartilage with calcein and DAPI to calculate the live-cell rate. The chondrogenic phenotype was determined by analyzing the mRNA levels of type II collagen alpha 1 (Col2A1), type I collagen alpha 2 (Col2A1), and SOX9. Besides, the pyroptosis process was determined by the mRNA levels of caspase-1/5, GSDMD, IL-1β, and IL-18. We also explored the preventive role and therapeutic role of GSDMD inhibitors in mechanical injury via culturing the cartilage before and after the compression, respectively. Mechanical compression injured the viability and function of CHs in cartilage partly based on the pyroptosis. The pretreatment of GSDMD inhibitor in cartilage before injury could maintain the live cells and Col2A1 expression and prevent pyroptosis after injury. Besides, supplying the cartilage with GSDMD inhibitor after injury also alleviated the cell death and dysfunction of CHs, and suppressed the pyroptosis. Using an inhibitor of GSDMD can play a preventive role and play a therapeutic role in the mechanical injury of cartilage.