Immunofluorescent microscopic investigation of the distal arrector pili: a demonstration of the spatial relationship between alpha5beta1 integrin and fibronectin.

Currently there is limited knowledge regarding the anatomy of the distal arrector pili (AP) muscle. A previous study implicated fibronectin and alpha5beta1 integrin binding as the anchor between the AP and the extracellular matrix (ECM). The purpose of this study was to strengthen this hypothesis. Serial frozen sections of human scalp skin were double-labeled via immunofluorescent staining for alpha5beta1 with fluorescein and fibronectin with rhodamine, followed by fluorescent microscopy. Granular staining for alpha5beta1 with fluorescein and smooth staining for fibronectin with rhodamine were seen at the periphery of the AP muscle bundles and along the distal fibers. Precise co-localization of alpha5beta1 and fibronectin was observed at the AP-ECM interface by means of a dual filter. Analysis of variance was used on the relative density of staining for each epitope. Staining for both epitopes was significantly brighter at the distal fibers than at the middle or proximal portions of the muscle. A computerized three-dimensional reconstruction provides a detailed picture of the microanatomy of the distal AP, which allows mathematical evaluation of the forces of contraction. The anatomic co-localization between alpha5beta1 and fibronectin strengthens our hypothesis that interaction of these epitopes mediates the attachment of the distal AP to the ECM.

Immunohistochemical evaluation of androgen receptors in genital and extragenital lichen sclerosus: evidence for loss of androgen receptors in lesional epidermis.

BACKGROUND: Reduction of lichen sclerosus has been seen with topical testosterone, and spontaneous resolution has been attributed to increasing androgen levels. OBJECTIVE: Our purpose was to investigate the role of androgens in lichen sclerosus by studying lesional skin and site-specific normal skin for the presence of androgen receptors. METHODS: Immunoperoxidase staining for androgen receptors was performed on lesional tissue from 31 patients and microscopically compared with site-specific normal skin. RESULTS: Androgen receptors were present in normal genital and extragenital skin. Lesional genital and extragenital areas showed decreased staining compared with site-specific controls. Finally staining was decreased in histologically well-developed lesions compared with early lesions. CONCLUSION: This study provides evidence for the loss of androgen receptors with disease progression in both genital and extragenital skin affected by lichen sclerosus. These findings support a hormonal pathogenesis of lichen sclerosus and may be significant in the treatment of the disease.