Background. Genetic deletion of neutral endopeptidase (NEP), a cell-surface metalloprotease that degrades proinflammatory peptides, exacerbates lung injury induced by pancreatic elastase in a model of pancreatitis-associated lung injury. We tested 3 hypotheses: (1) genetic deletion of NEP prólongs lung recovery after elastase injections; (2) elastase-mediated lung injury is associated with down-regulation of NEP; and (3) pretreatment of NEP (-/-) and (+/+) animals with recombinant human NEP (rhNEP) reduces pulmonary damage in this model. Methods. NEP (+/+) or (-/-) mice were injected with pancreatic elastase (0. 085 U/g/dose intraperitoneally) or saline carrier at t = 0 hours and t = 1 hour. Some mice were pretreated with rhNEP (3 mg/kg intraperitoneally). Serum elastase, lung histologic score, myeloperoxidase, and NEP activities were measured at 4, 8, or 12 hours. Results. NEP (-/-) mice had worse pulmonary inflammation at 4 and 8 hours versus (+/+) mice. Lung NEP activity was similar in dastase-treated and control (+/+) animals. Pretreatment with rhNEP reduced myeloperoxidase and improved histology at 4 hours in NEP (-/-) and (+/+) mice. Conclusions. Pancreatic elastase induces lung injury, that is worse and prolonged in NEP (-/-) mice. Pretreatment with rhNEP ameliorates this injury. Thus, upregulation of NEP is a potential therapeutic approach for pancreatitis-associated lung injury.
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