Immunohistochemical and light and electron microscopic study of the basement membrane in photoaged skin

Background The basement membrane plays an important role in maintaining a healthy epidermis and dermis, and repeated damage destabilizes the skin and accelerates the aging process. This study was carried out to detect the changes in human skin basement membrane in sun-exposed skin compared with sun-protected skin. Particpants and methods Skin biopsies were taken from sun-exposed and sun-protected skin of 10 male individuals aged between 50 and 60 years and processed for light and electron microscopic examination of the changes of the basement membrane. Immunohistochemical assessment of laminin and matrix metalloproteinase-1 (MMP-1) expression in skin biopsies was also carried out. Results Histological examination of sections of sun-exposed skin revealed that the basement membrane was discontinuous and the collagenous fibers of the underlying connective tissue were discrete in comparison with sun-protected skin. Immunoreactivity for laminin was decreased, whereas that for MMP-1 was markedly increased in sunexposed skin as compared with sun-protected skin. Conclusion The results of the current study revealed that the structure of the basement membrane was affected in sun-exposed skin as regards thickness, continuity, and structure. Increased activity of MMP-1 accounts at least in part for the disruption of the basal lamina and degradation of collagenous fibers of the dermis.