Expression of integrins in human nail matrix

The aim of this study was to characterize cell-cell and cell-matrix interaction by evaluating the expression of different integrins in the nail matrix. Nail biopsies were obtained from two cadaver fingers, and eight patients with ingrowing toenails. Frozen sections were stained by indirect immunofluorescence using anti-α1, anti-α2, anti-α3, anti-α4, anti-α5, anti-α6, anti-αv, anti-β1, anti-β4 and anti-ICAM-1 monoclonal antibodies. Biopsies from normal human foreskin were evaluated as controls. α1, α4 and α5 subunits were absent from both nail matrix and normal human skin. α2, α3 and β1 subunits were expressed in the basal and suprabasal layers of nail matrix, but only in the basal layer of skin epidermis. α6 and β4 subunits were strongly expressed in the basement membrane zone and in the basal layer of both nail matrix and epidermis. The αv subunit was expressed in the basal layer of nail matrix. ICAM-1 was not expressed in nail matrix epidermis. Our findings show that despite the distinctive features of the nail apparatus, compared with the epidermis, the pattern of integrin expression is similar, although some differences in the distribution of α2, α3 and β1 subunits are detectable. These are probably related to the peculiar differentiation and keratinization of the nail.