Immunolocalization of Tenascin-C, α9 Integrin Subunit, and αvβ6 Integrin During Wound Healing in Human Oral Mucosa

Abstract

Tenascin-C (TN-C) and its isoforms are multidomain extracellular matrix (ECM) proteins that are believed to be involved in the regulation of stromal–epithelial interactions. Some of the interactions between TN-C and cells are mediated by integrins. In this study we analyzed the expression of TN-C and its large molecular weight splice isoform (TN-CL) and the putative TN-C-binding α9 and αvβ6 integrins during human wound repair. In 3-day-old oral mucosal wounds, immunoreactivity for α9 integrin localized abundantly at the migrating basal wound epithelial cells. TN-C and TN-CL were localized in the matrix between and underneath α9-expressing epithelial cells. In parallel with gradual downregulation of α9 integrin immunoreactivity in 7-day and older wounds, the expression of αvβ6 integrin was temporarily induced. Integrin αvβ6 co-localized in the same area as TN-C and TN-CL immunoreactivity at the cell–cell contacts of the basal and suprabasal cell layers of the wound epithelium. During granulation tissue formation and reorganization from 7 to 28 days after wounding, TN-C and TN-CL were abundantly localized in the granulation tissue. The findings show that TN-CL is expressed under the migrating epithelial front and in the granulation tissue during matrix deposition in wound repair. Preferential localization of α9 integrin in migrating epithelial cells and of αvβ6 integrin in epithelium after wound closure suggests different functions for these integrins in wound repair.