ABSTRACT
Plasminogen activators are serine proteases that catalyze the conversion of plasminogen to plasmin. The plasminogen activating activity within a tissue is tightly regulated. Cell synthesis of plasminogen activators is modulated by various cytokines. Once secreted, the activities of the plasminogen activator enzymes are modulated by a complex network of molecular interactions. The plasminogen activator proteolytic cascade has been implicated in the regulation of cell growth and differentiation, both of which occur continually in normal human epidermis. The keratinocyte is the predominant cell type that comprises the epidermis. The psoriatic lesion is characterized by epidermal thickening consequent to increased proliferation of the basal and some suprabasal keratinocytes. In situ zymography studies suggest that the focal increases in tissue-type antigen are reflected in a coordinate induction of its enzymatic activity. Studies from several laboratories demonstrate that increased plasminogen activator activity is characteristic of psoriatic epidermis.
