Pulmonary edema fluid from patients with acute lung injury augments in vitro alveolar epithelial repair by an IL-1β-dependent mechanism

Efficient alveolar epithelial repair is crucial for the restoration of the injured alveolar epithelial barrier in patients with acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). We hypothesized that pulmonary edema fluid from patients with ALI/ARDS would inhibit alveolar epithelial repair as measured in an in vitro epithelial wound-repair model using the human alveolar epithelial-like cell line A549. In contrast to our initial hypothesis, pulmonary edema fluid from patients with ALI/ARDS increased alveolar epithelial repair by 33 +/- 3% compared with pooled plasma from healthy donors (p < 0.01). By contrast, the plasma and the pulmonary edema fluid from patients with hydrostatic pulmonary edema, and the plasma from patients with ALI/ARDS had similar effects on epithelial repair as pooled plasma from healthy donors. Inhibition of interleukin-1<beta> (IL-1 beta) activity by IL-1 receptor antagonist reduced alveolar epithelial repair induced by ALI/ARDS edema fluid by 46 +/- 4% (p < 0.001), indicating that IL-1<beta> contributed significantly to the increased epithelial repair. In summary, pulmonary edema fluid collected early in the course of ALI/ARDS increased alveolar epithelial repair in vitro by an IL-1 beta -dependent mechanism. These data demonstrate a novel role for IL-1 beta in patients with ALI/ARDS, indicating that IL-1 beta may promote repair of the injured alveolar epithelium.