Life-threatening hemorrhage and prolonged wound healing are remarkable phenotypes manifested by complete plasminogen activator inhibitor-1 deficiency in humans

Summary. Background: Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological regulator of urokinase plasminogen activator (uPA) and tissue plasminogen activator (tPA) activity. A number of studies have shown that elevated levels of PAI-1 are related to pathological states such as an increased risk of arterial thrombotic events and a poor prognosis for cancer patients; however, there are few reports about PAI-1 deficiency in humans because the disorder is very rare. Objective: To understand the in vivo impact of a complete PAI-1 deficiency, Serpine1−/− mice were generated; a number of in vivo studies have been conducted to elucidate the function of PAI-1 using Serpine1−/− mice. The phenotypes demonstrated in Serpine1−/− mice, however, were quite different from those in humans. Therefore, it is necessary to find out and analyze SERPINE1 deficiency in humans. Patient and methods: The patient is a 47-year-old woman who has had multiple episodes of major bleeding. Although most of the patient’s blood coagulation factors were functionally normal, her PAI-1 antigen levels were undetectable. Therefore, DNA sequencing of the SERPINE1 gene were analyzed. Results: The proband had a homozygous 1-bp duplication (C) at exon 3 (c.356dupC; p.Ile120AspfsX42). Both wild-type PAI-1 (42.7 kDa) and mutated (Mut) PAI-1 (14.7 kDa) were expressed in COS-1 cells, although the level of Mut PAI-1 expressed in the cell lysates was much lower. Wild-type PAI-1 was observed in the culture supernatant, whereas no Mut PAI-1 was detected in the supernatant. Conclusions: Considering the results of the present study, the translation of mouse studies to humans must be performed with great care.