Comparative inhibitory effects of vitamin D-3 and an analogue on normal and psoriatic epidermis in organ culture

Recently, there have been many vitamin D-3 analogues synthesized and tried in the treatment of psoriasis, In the experiments reported here we observed and compared their effects on normal and psoriatic epidermis in organ cult ure in vitro. We employed a nerv vitamin D-3 analogue, 22-oxa-calcitriol (O CT), the effect of which was compared with that of calcitriol (1,25-D-3). B oth caused suppression of proliferation of normal and psoriatic epidermis, dependent upon concentration and culture time. Histologically, in the prese nce of the agents, degeneration started from the top of the epidermis downw ards. This is the first report of cell degeneration as a direct effect of v itamin D, The nature of the degeneration was evaluated by electron microsco py (EM) and by the in situ nick end labeling technique (TUNEL), and these s tudies revealed that the degeneration involved necrosis rather than apoptos is, This in vitro method may be useful to assess the effectiveness of newly synthesized vitamin D, analogues in the treatment of psoriasis.