Studies of cell and organ culture of psoriatic and normal epidermis in vitro

Feasibility of in vitro culturing of lesional psoriatic keratinocytes in medium containing high calcium concentrations

Lesional psoriatic keratinocyte (LPK) culture is considered to be difficult under high-Ca2+ conditions in the absence of special proliferative agents. Using a permeable collagen membrane, we obtained a culture of LPKs under high-Ca2+ conditions without any special proliferative agents. Single-cell suspensions were prepared from the epidermis of chronic psoriatic plaques. Cells were inoculated on the collagen membrane suspended slightly above the bottom of a Petri dish. We used a culture medium of Eagle's MEM containing 10% fetal calf serum. LPKs attached to the membrane 12 h after inoculation and gradually spread. They reached a confluent state by the 10th day of culture. We measured the concentrations of TGF alpha and IL-6 in the medium of LPKs, and compared these with the concentrations in normal keratinocyte (NK) cultures. Significantly increased secretion of TGF alpha by LPKs was observed during the initial phase but this secretion subsequently decreased. Concentrations of IL-6 were below the detectable level in both of NKs and LPKs throughout the observation period. Our results demonstrate that cultured LPKs under high-Ca2+ conditions secrete a larger amount of TGF alpha but not IL-6. Our cell culture system, which allows LPKs to spread and stratify, contributes to the study of the pathogenesis of psoriasis.

Comparative analysis of normal and psoriatic skin both in vivo and in vitro

The morphological and biochemical characteristics of psoriasis are well documented, but the pathogenesis of this disease is not clearly understood. A variety of in vitro models of psoriasis have been developed in attempts to identify the trigger factors, but no model so far reproduces the stable psoriatic phenotype accurately. In the present work, we initially checked the immunohistochemical distribution of proliferation/differentiation markers in psoriatic skin in vivo, and our results largely confirm previously reported data. However the study was performed using a new series of monoclonal antibodies to keratin. Subsequently we took normal or psoriatic skin biopsies, reconstructed skin equivalents using a recently described model and analysed the proliferation/differentiation status of the resulting epidermis. Dramatic morphological and antigenic differences were found between normal and psoriatic skin in vivo, but whatever the source of the initial biopsy, a unique in vitro phenotype was obtained in the reconstructed epidermis. This phenotype was marked by mild hyperproliferation and an altered distribution of differentiation-associated antigens suggesting a need for extracutaneous stimuli to maintain the psoriatic phenotype in vitro.

Influence of culturing temperature and proteinase inhibitors on the spontaneously occurring changes in the organ culture of psoriatic skin

Skin explants from involved psoriatic lesions showed dissociation of keratinocytes, dermal-epidermal separation and degenerative changes such as cytoplasmic swelling of subcorneal prickled cells within 24 h after culture initiation at 37 degrees C in the absence of fetal bovine serum (FBS). These histological changes developed time dependently, while normal skin explants did not exhibit such phenomena. Some of the uninvolved psoriatic skin explants showed only degenerative change 48 to 72 h after culture initiation at 37 degrees C. To determine the nature of these spontaneously occurring changes in psoriatic skin explants and then to approach the pathogenesis of psoriasis, the effects of FBS, various proteinase inhibitors (PIs) and culturing temperature (37, 31, 24 degrees C) were examined in skin organ culture of normal and involved psoriatic skin. At 37 degrees C, only serine PIs (5 or 10 mg/ml of soybean trypsin inhibitor (SBTI), 1000 KIU/ml of aprotinin, or 2 mg/ml of camostat mesilate in the medium) or FBS (20% in the medium) could suppress the occurrence of dissociation of keratinocytes and dermal-epidermal separation but not the degenerative change in involved psoriatic skin explants, while other types of PIs did not exhibit any such inhibition. When the culturing temperature was reduced from 37 degrees C to 31 or 24 degrees C, the formation of dissociation of keratinocytes and dermal-epidermal separation was almost non-existent and only moderate degenerative change was observed. The addition of FBS or serine PIs to the culture at 31 degrees C revealed the formation of very weak degenerative change.(ABSTRACT TRUNCATED AT 250 WORDS)

Histologic characteristics of lichen planus transplanted onto nude mice and cultured in vitro

Typical confluent lesions of lichen planus were transplanted onto nude mice and cultured in organ culture. The characteristic histologic appearance of lichen planus disappeared after grafting and became similar to normal skin within 6 weeks on nude mice; the dense lymphocyte infiltrate in dermis disappeared, the basal cell layer normalized, and the colloid bodies disappeared from epidermis, although some of them were found in dermis. The granular layer also normalized, but the stratum corneum remained hyperkeratotic 6 weeks after transplantation. In organ culture, characteristic histologic features of lichen planus disappeared in 3-5 days via a rapid necrosis of the upper part of the epidermis and formation of a new, normal-looking basal epidermis. These results suggest that lesions of lichen planus are primarily dependent on the influence of the host to maintain their typical histologic appearance.