[Usefulness of a protease inhibitor (urinastatin) in ARDS with infectious diseases]

The usefulness of urinastatin (UST) for adult respiratory distress syndrome (ARDS) induced by gram-negative sepsis was evaluated in clinical and experimental studies. Twelve cases of clinical septic ARDS were treated with combination therapy of UST and methylprednisolone (M-PSL). Ten out of 12 responded favorably. This result was considered to some extent to be better than that of our previous experience with single administration of M-PSL for patients with septic ARDS. Pathophysiologic experiments on UST in endotoxic status were then performed. Immediately after the intravenous administration of endotoxin to rats, serum levels of beta-glucuronidase and elastase released from PMNs were increased and pulmonary edema was observed at 48-hours after the endotoxin injection. Various degrees of pulmonary edema were also observed by the intravenous administration of beta-glucuronidase and PMNs-elastase. These changes induced by the endotoxin were significantly inhibited by the intraperitoneal administration of UST, and they were inhibited more by the combination therapy of UST and M-PSL. In an in vitro study, significantly large amounts of beta-glucuronidase and elastase were released from PMNs by incubating human PMNs with endotoxin. By adding UST to this system, the release of these PMNs proteases was inhibited. These results suggested that UST neutralizes the PMNs-elastase release in the status endotoxemics, and consequently resulted in a better prognosis in cases of septic ARDS.