The biological effects of lung-derived mediators on the liver.

Despite the use of lung-protective mechanical ventilation (MV), the mortality of patients with acute lung injury remains at 30 to 40%, predominantly due to multiorgan failure. The objective of this study was to determine the biological significance of lung-derived mediators on peripheral organ inflammation. The authors utilized an isolated perfused mouse lung model of lipopolysaccharide (LPS)-induced lung inflammation and protective MV to collect lung-derived mediators. Aliquots of perfusate from these animals (or appropriate controls) were then injected intravenously into a cohort of normal animals whose livers were subsequently assessed in vivo using intravital video microscopy. Perfusate from LPS-inflamed lungs contained significantly higher concentrations of inflammatory mediators than perfusate from saline-instilled lungs. Assessment of livers in the second cohort of animals 120 minutes after perfusate injection revealed decreased sinusoidal blood flow, leukocytosis, and increased cell death in those receiving perfusate from LPS-inflamed lungs compared to perfusate from saline controls. There were no differences between control animals that received pure perfusate or pure LPS mixed with perfusate. These results showed that lung-derived mediators had a significant biological effect on nonpulmonary organs within a short period of time after administration. Therapies targeting these mediators may prevent multiorgan failure and death in patients with acute lung injury.