Surgery-Induced Stress Promotes SOX9 Nuclear Localization and Increases COL2A1 in Tracheal Cartilage

Abstract

Objective:

Airway reconstruction triggers a surgery-induced stress (SIS) response, but its effect on cartilage regeneration remains elusive. SOX9 regulates cartilage regeneration by promoting type II collagen production and may aid in repair; however, the role of SOX9 in response to SIS is unclear. We utilized a mouse model to validate SOX9 nuclear expression in tracheal chondrocytes and assess its localization after segmental tracheal replacement.

Methods:

Tracheas from C57BL/6J mice were digested using Dispase-Collagenase-Trypsin, then collagenase II to isolate chondrocytes for primary culture. Syngeneic tracheal grafts were harvested from donor animals, and a 3 to 4 mm tracheal graft was implanted orthotopically to assess chondrocyte function in vivo. At 1 month, graft, anastomosis, and adjacent host tissues were harvested. Samples were stained for SOX9 and COL2A1, and their localization was analyzed with ImageJ.

Results:

Primary tracheal chondrocytes showed strong nuclear SOX9 and cytoplasmic COL2A1 expression. One month after orthotopic tracheal replacement, SOX9 nuclear colocalization increased in the host and anastomosis regions (P = .0269 and P = .0262, respectively), but not in the graft (P = .5958). COL2A1 intensity in the cartilage matrix was significantly higher in graft, host, and anastomosis compared to native cartilage (all P < .01), with no morphological differences.

Conclusion:

After tracheal reconstruction, increased SOX9 and COL2A1 intensities indicate a potential chondrocyte response to SIS. SOX9 nuclear localization may be involved in regulating COL2A1 in tracheal chondrocytes during cartilage injury and repair. This supports a possible role for SOX9 in maintaining cartilage function and its potential as a therapeutic target to improve graft integration and airway stability.