Immunohistological study of involucrin expression in Darier's disease skin

Résumé : Darier's disease (DD) is an autosomal dominant skin disorder characterized by acantholysis and abnormal keratinization. The gene responsible for DD, ATP2A2 encodes for the sarco/endoplasmic reticulum (ER) Ca2+-ATPase isoform 2 protein. Involucrin, considered as a marker of terminal epidermal differentiation, could be altered in some keratinization disorders including DD. An immunohistochemical staining using anti-involucrin antibody was carried out on 16 DD patients epidermis. Involucrin staining was compared with biopsies from cutaneous lesions of three healthy individuals and of patients with Hailey-Hailey disease (five cases) and Mal de Meleda (four cases). A semi-quantitative analysis was performed in order to evaluate involucrin immunostaining on the basis of intensity, extension and epidermal distribution. The involucrin expression was examined afterward with confocal laser scanning microscopy. In contrast to normal skin, all DD cases showed premature expression of involucrin in the lower epidermal layers in four cases with a strong labeling in both keratinocytes cell membrane and cytoplasm. Other keratinization disorders share premature expression of involucrin but displayed differences in cytoplasm/cell membrane labeling. DD skin displayed a constant immunohistochemical involucrin pattern characterized by both premature expression and a particular cytoplasmic/cell membrane localization distribution.