Histological Changes in the Skin with Innate Ageing / 대한피부과학회지

ABSTRACT

BACKGROUND: It is a popular notion that cutaneous ageing includes two distinct phenomenon; true ageing, a universal presumably inevitable change attributable to the passage of time alone, and photoageing, changes attributable to chronic habitual sun exposure that are neither universal nor inevitable. Numerous investigations with experimental animals, in vitro skin models have been conducted, although, few histological studies to date have attempted to announce fundamental morphological changes with innate ageing. OBJECTIVE: We compared skin derived from the breast of old and young persons using light microscopy to discern structural changes in epidermal and dermal morphology with advancing age. METHODS: The histological, immunohistochemical studies were performed with normal skin sections of thirty donors who were diagnosed with breast cancer. They were classified into three age cohort groups; nine into group I (22 to 38), twelve into group II(40 to 52), and nine into group III(54 to 87). We chose the breast as an area that might closely resemble intrinsically aged skin. This region is relatively shielded from photoageing by its anatomical location. Analysis of data was performed using the Kruskal-Wallis and ANOVA test for dermal parameters based on a 5-point rating scale, and a simple regression test for a positive rate of immunoreactants. Results: 1. Light microscopic appearance of aged skin revealed a more flattened epidermis than young skin. There was no trend for an increase in epidermal melanin content per unit area on Fontana-Masson staining. There was an age-associated decrease in the Ki-67 positive rate(p<0.001), the density of Ki-67 positive cells declined approximately 1.16% per decade in photoprotected skin(p<0.001). The number of S-100 positive cells declined approximately 4.4/mm width along the dermo-epidermal juction per decade in photoprotected skin(p<0.001). The expression of differentiation markers(keratin 1, involucrin, filaggrin, loricrin) were not different among the three age cohort groups. 2. With advancing age, there was an attenuation in the number and diameter of elastic fibers in the papillary dermis and an increase in the number and straightness of the same fibers in the reticular dermis. The collagen fibers are arranged in sparse bundles in disarray, and/or aggregates of loosely woven, straight fibers in the aged skin. There was an apparent, age-related decrease in the stainability of ground substances in the papillary dermis on colloidal iron staining. Conclusions: Our data documents semi-quantitative differences among three groups in intrinsically aged breast skin and provide the framework for future research to evaluate the ageing process.