Influences of Human Cytokines and Mixed Lymphocyte Culture-derived Cytokines on the Proliferation and Differentiation of the Living Skin Equivalent

Har, Tai Young; Kim, Nack In

Abstract

BACKGROUND: A living skin equivalent(LSE) is useful as a skin replacement and as a model system for basic studies such as skin physiology and pathology. This system attempts to reproduce in vitro the cell-cell and cell-matrix interactions responsible for cell differentiation. Recently, there have been many studies that cytokines(IL-1, IL-6, IL-8, TGF-beta, TNF-alpha) play an important role in proliferating skin disease, especially psoriasis. Hesides, many cytokines can influence the proliferation and differentiation of normal human keratinocytes.
OBJECTIVE
AND METHODS: In the present study, the author investigated the proliferation and differentiation of cytokines in LSE as compared with control skin using histopathological and immunohistochemical staining methods. The author also investigated the proper concentration of cytokines on the proliferation of cultured human keratinocytes.
RESULTS
Morphological analysis of LSE showed reorganization of epidermal layers with the appearance of a distinct basal laer and of a hyperkeratotic horny layer. We demonstrated that the fine granules resembling keratchyaline granules were observed in the control and cytokine treated groups(IL-l alpha, IL-2, IL-6, TNF-alpha). We observed significant epidermal proliferation in the PBMC (25%), IL 6(10ng), TGF-beta(20ng) treated groups than in the control group(p<0.01). Immunohistochemical analysis demonstrated that the terminal differentiation marker involucrin was expressed at the level of the prickle cell layer in the cytokine treated groups. Also the cellular proliferation marker PCNA was expressed at the level of the basal layer in the PBMC(25%), IL-2(100ng) and IL-6(10ng) treated groups.
CONCLUSION
The results indicate that cytokine IL-6 and TGF-beta can induce a proliferation and differentiation of the epidermis in this in vitro model.