Evidence of increased keratinocyte proliferation in air-liquid interface cultures of non-bullous congenital ichthyosiform erythroderma.

Modern pharmacological and dermatological research requires the use of appropriate in vitro models which permit a faithful reproduction of various aspects of the in situ situation. The air-exposed culture of keratinocytes on dead de-epidermized dermis is one of the best models of in vitro epidermal differentiation known at the moment. In this study, we verified the model's validity for the reproduction of a hyperproliferative genodermatosis: non-bullous congenital ichthyosiform erythroderma. We used subcultured epidermal keratinocytes originating from normal and ichthyotic patients. Light and electron microscopy of pathological cultures disclosed, on day 14, a terminally differentiated epidermis with a marked granular layer and hyperkeratosis which, however, was not dramatically different from the normal controls. On day 25, the normal cultures displayed an even more pronounced hyperkeratosis and hypergranulosis, whereas the reconstructed epidermis of pathological origin presented a considerable reduction of the viable non-keratinized compartment and a focal parakeratosis. Indirect immunofluorescence revealed the expression of several differentiation markers which were not observed in the immersed culture models (e.g. the desmosome- and differentiation-related antigens KM48 and G36-19). Abundant keratohyalin granules were stained with AKH1 antibody and observed even in the deep epidermal layers, but no profilaggrin-filaggrin conversion could be detected biochemically.(ABSTRACT TRUNCATED AT 250 WORDS)