Plasma receptor interacting protein kinase-3 levels are associated with acute respiratory distress syndrome in sepsis and trauma: a cohort study.

BACKGROUND: Necroptosis, a form of programmed cell death mediated by receptor interacting serine/threonine-protein kinase-3 (RIPK3), is implicated in murine models of acute respiratory distress syndrome (ARDS). We hypothesized that plasma RIPK3 concentrations in sepsis and trauma would be associated with ARDS development and that plasma RIPK3 would reflect changes in lung tissue RIPK3 in a murine model of systemic inflammation. METHODS: We utilized prospective cohort studies of critically ill sepsis (n = 120) and trauma (n = 180) patients and measured plasma RIPK3 at presentation and 48 h. Patients were followed for 6 days for ARDS by the Berlin definition. We used multivariable logistic regression to determine the association of plasma RIPK3 with ARDS in each cohort, adjusting for confounders. In mice, we determined whether plasma and lung tissue RIPK3 levels rise concomitantly 4 h after injection with lipopolysaccharide and ZVAD-FMK, an apoptosis inhibitor. RESULTS: The change in plasma RIPK3 from presentation to 48 h (ΔRIPK3) was associated with ARDS in sepsis (OR 1.30, 95% CI 1.03-1.63, per ½ standard deviation) and trauma (OR 1.79, 95% CI 1.33-2.40). This association was not evident for presentation RIPK3 levels. Secondary analyses showed similar findings for the association of ΔRIPK3 with acute kidney injury and 30-day mortality. Mice injected with lipopolysaccharide and ZVAD-FMK had significantly higher plasma (p < 0.001) and lung (p = 0.005) RIPK3 than control mice. CONCLUSIONS: The change in plasma RIPK3 from presentation to 48 h in both sepsis and trauma patients is independently associated with ARDS, and plasma RIPK3 may reflect RIPK3 activity in lung tissue.

In vitro surfactant protein B deficiency inhibits lamellar body formation.

Surfactant protein (SP) B is essential for normal pulmonary surfactant activity and lamellar body genesis in type 2 cells. However, the role of SP-B in lamellar body genesis is poorly understood. We developed an adenovirus vector expressing antisense SP-B as an alternative in vitro model of SP-B deficiency to begin to explore the role of SP-B in lamellar body genesis. RT-PCR analysis revealed that antisense SP-B expression interfered with translation of endogenous SP-B mRNA. Antisense SP-B expression resulted in reliable in vitro reproduction of many features of SP-B deficiency, including absent mature SP-B and decreased lamellar bodies and SP-C. Light and electron microscopy demonstrated significant reductions in lamellar body number. Western blotting revealed a significant reduction in mature 8-kD SP-B protein and decreased mature SP-C. Our data indicate that antisense SP-B can be effectively used to replicate the SP-B-deficient type 2 cell phenotype in vitro, and provides an attractive alternative to transgenic models for the further study of the role of SP-B in lamellar body genesis.