Immunohistochemical localization of very late activation integrins in healthy and diseased human gingiva.

The beta 1-integrins (VLA family) are cellular adhesion molecules (CAM) that play a major role in cell-cell and cell-matrix interactions. The expression pattern of CAM was studied in 5 clinically normal volunteers with healthy gingiva and in 18 patients with clinically different stages of periodontitis. In healthy human gingiva alpha 2, alpha 3 and alpha 6 integrin chains were found in a characteristic distribution, showing a broad continuous expression on the junctional and sulcular epithelium sites. The expression of these integrins was demonstrated primarily on the basal cell layers and in some cells of the stratum spinosum. Inflammatory stages of periodontitis revealed further upregulation of alpha 2, alpha 3 and alpha 6 integrins into the junctional and sulcular epithelial cells, which correlated with the stage of the periodontitis and the extent of the cellular infiltration. alpha 4 and alpha 6 were found to be the predominant beta 1 integrin chains on inflammatory cells. The amount of alpha 4 and alpha 6 positive infiltrative cells increased with the number of inflammatory cells. VCAM-1, the corresponding cell-cell ligand of VLA-4 (alpha 4) was present on the majority of subepithelial vessels in all stages of gingivitis and periodontitis. The alpha 5 subunit was expressed on both endothelium and gingival connective tissue cells. Samples from advanced periodontitis cases showed a higher number of alpha 5 positive mononuclear cells. In comparison to normal epidermis, human gingival epithelial cells express higher levels of integrins. This expression is further upregulated in advanced stages of periodontitis, indicating changes of the beta 1 integrin organization.