[Changes in Chemokine Receptor 4, Interleukin-6, and Collagen X Expression in the ATDC5 Cell Line Stimulated by Cyclic Tensile Strain and Stromal Cell-derived Factor-1]

Objective: This study further explores the stromal cell-derived factor-1 (SDF-1)/chemokine receptor 4 (CXCR4) signaling axis mechanism in temporomandibular joint osteoarthritis (OA) by detecting the changes in CXCR4, interleukin (IL)-6, and collagen X expression in the ATDC5 cell line stimulated by the cyclic tensile strain and SDF-1.

Methods: Insulin-transferrin-selenium (ITS) was used to induce ATDC5 cells to differentiate into chondrocyte-like cells. After three weeks, the cells were divided into two groups: those with and without cyclic tensile strain. These groups were further divided into the negative control and SDF-1 groups. Strain force of 20% was applied. After 12 h, the total proteins were extracted from cells of the four groups, and Western blot analysis was used to detect the changes in CXCR4, IL-6, and collagen X expression.

Results: SDF-1 could enhance CXCR4, IL-6, and collagen X expressions in the chondrocytes, and 20% tensile strain force could further upregulate the three factors.

Conclusion: Under abnormal tensile force, SDF-1 can upregulate its specific receptor CXCR4, thus increasing its-binding efficiency and resulting in the activation of the SDF-1/CXCR4 axis. This condition enhances the expressions of IL-6 and other inflammatory factors and directly damages to cartilage tissue. Such damage directly promotes chondrocyte hypertrophy, which enhances collagen X expression.