Immunolocalization of tenascin-C, alpha 9 integrin subunit, and alpha v beta 6 integrin during wound healing in human oral mucosa

Tenascin-C (TN-C) and its isoforms are multidomain extracellular matrix (EC M) proteins that are believed to be involved in the regulation of stromal-e pithelial interactions. Some of the interactions between TN-C and cells are mediated by integrins. In this study we analyzed the expression of TN-C an d its large molecular weight splice isoform (TN-C-L) and the putative TN-C- binding alpha 9 and alpha v beta 6 integrins during human wound repair. In 3-day-old oral mucosal wounds, immunoreactivity for alpha 9 integrin locali zed abundantly at the migrating basal wound epithelial cells. TN-C and TN-C -L were localized in the matrix between and underneath alpha 9-expressing e pithelial cells. In parallel with gradual downregulation of alpha 9 integri n immunoreactivity in 7-day and older wounds, the expression of alpha v bet a 6 integrin was temporarily induced. Integrin alpha v beta 6 co-localized in the same area as TN-C and TN-C-L immunoreactivity at the cell-cell conta cts of the basal and suprabasal cell layers of the wound epithelium. During granulation tissue formation and reorganization from 7 to 28 days after wo unding, TN-C and TN-C-L were abundantly localized in the granulation tissue . The findings show that TN-C-L is expressed under the migrating epithelial front and in the granulation tissue during matrix deposition in wound repa ir. Preferential localization of alpha 9 integrin in migrating epithelial c ells and of alpha v beta 6 integrin in epithelium after wound closure sugge sts different functions for these integrins in wound repair.