Wound repair-induced expression of a stromelysins is associated with the acquisition of a mesenchymal phenotype in human respiratory epithelial cells.

Wound repair involves many processes including cell migration, provisional matrix deposition, and remodeling. All of these processes are likely to be affected by matrix-modifying enzymes. Members of the matrix metalloproteinases family are physiologic mediators of the extracellular matrix degradation. Within this matrix metalloproteinases family, stromelysins can degrade many components of the extracellular matrix. We therefore tested the hypothesis that stromelysins could be produced by human surface respiratory epithelial (HSRE) cells repairing a wound. Experimental wounds were created in vitro in HSRE cell cultures and in situ in human bronchial mucosa maintained in organ culture. Stromelysin production was measured by casein-gel zymography in cellular protein extracts derived from repairing migratory and nonrepairing stationary cells of wounded HSRE cell cultures. Stromelysin-producing cells present in cell and tissue cultures were localized and characterized using immunofluorescence techniques. Zymographic and immunofluorescence techniques showed that stromelysins were produced exclusively by the migratory HSRE cells. Zymogram analysis showed that stromelysins were overexpressed and overactivated during the wound repair process, with the maximal production observed at wound closure. Using an anti-cytokeratin 14 antibody, we identified stromelysin-3-producing cells as basal epithelial cells. Moreover, most stromelysin-3-producing cells expressed the mesenchymal marker vimentin. Similar to stromelysins localization, vimentin-positive HSRE cells were exclusively located in the wounded area, and they were also positive to cytokeratin 14. In conclusion, stromelysins are suggested to be involved in HSRE cell migration and extracellular matrix remodeling during wound repair. Furthermore, stromelysin production by repairing HSRE cells is linked to the acquisition of a mesenchymal phenotype. HSRE cell migration may then be associated with the shift from an epithelial to a mesenchymal phenotype.