Cyclosporine A inhibits tPA mRNA transcription in A431 cell line

Cyclosporine A (CyA), a well established treatment of psoriasis, is a highly lipophilic cyclic undecapeptide mainly used for its immunosuppressive properties and exerting a wide spectrum of biological activities including fungicidal antiproliferative and anti-inflammatory effects. Plasminogen activators (PA), urokinase (UK, M(r) 55,000) and tissue type plasminogen activators (tPA, M(r) 74,000), physiologically catalyze the conversion of the plasminogen to the wide spectrum proteinase plasmin. UK and tPA are involved in cell growth, differentiation and migration. It has recently been shown that psoriatic epidermis is provided with abnormal tPA-dependent PA activity and that in lesional epidermis elevated tPA mRNA levels are present. It has been suggested that the tPA-dependent PA activity is a marker of disease activity and is reversible with different topical and systemic treatments. In this preliminary study we investigate the effect of CyA on the tPA mRNA transcription on A431 keratinocytes cell line. Subconfluent A431 cell cultures have been treated with CyA at in vivo relevant concentrations (10, 7.5, 5 micrograms/ml) for 48 h. Northern blot analysis of total RNA extracted from cultured A431 cell line has been performed for detecting tPA mRNA. mRNA for tPA has been detected in the control samples whereas an evident decrease of tPA mRNA expression has been detected in the CyA-treated samples. These data suggest that CyA could have an effect in clearing psoriatic lesions also modulating the abnormal plasminogen activation i.e. tPA-dependent serinoproteinase activity.