Imbalance between plasminogen activator and its inhibitors in thiol-induced acantholysis

Pemphigus may be an idiopathic disease or a syndrome induced by drugs, mainly thiol drugs. Autoantibodies, always present in the idiopathic form but often lacking in the drug-induced one, may cause acantholysis by activating endogenous proteolytic enzymes. Pathogenesis of drug-induced pemphigus when antibodies are absent has not been elucidated yet. Extracts of skin tissues cultured for 4 days with penicillamine, captopril or thiopronine were assayed for the presence of plasminogen activator (PA) and plasminogen activator inhibitors (PAI) on agar fibrin plates. Moreover, uPA, tPA, and PAI-1 were identified in the extracts by immunoenzymatic assay. The results have shown progressively decreasing amounts of PAI-1 in penicillamine, thiopronine and captopril-cultured tissue extracts, respectively. This suggests that the acantholytic potential of thiol drugs is directly correlated to their capability of reducing PAI-1 in the epidermal cells leading to increased PA activity. This PA-PAI imbalance may be itself the cause of intraepidermal splitting.