The effect of LPS on cytokine synthesis and lung neutrophil influx after hepatic ischemia/reperfusion injury in the rat

Objective: To determine if cytokine responses and lung injury induced by intravenous (iv) lipopolysaccharide (LPS) at 4 hr were enhanced in rats that had been previously subjected to 30 min of total liver ischemia (Pringle's maneuver) followed by 24 hr or 3 days of reperfusion. Background: Many patients with liver trauma require occlusion of hepatic blood flow to control hemorrhage and facilitate repair. A significant number of these patients subsequently develop the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction (MOD) characterized by the release of cytokines and tissue neutrophil influx. Macrophages, including Kupffer cells, may be activated by ischemic injury and dysregulation of their response to LPS may contribute to the development of SIRS and acute respiratory distress syndrome. Methods: Adult male Sprague–Dawley rats were randomly divided into six groups: three groups received total hepatic ischemia for 30 min and three groups had a sham procedure. Twenty-four hours or 3 days after hepatic ischemia/reperfusion injury, rats were treated with LPS (5 mg/kg) or saline and monitored for 4 hr. We collected serum, bronchoalveolar lavage (BAL) fluid, and lung tissue. Results: Serum and BAL cytokine concentrations were significantly increased by iv LPS; however, hepatic ischemia/reperfusion injury 24 hr or 3 days before iv LPS ameliorated this cytokine response. The LPS-induced pulmonary neutrophil influx and histopathological changes were similar in sham and hepatic ischemia/reperfusion-injured groups. Conclusions: Hepatic ischemia/reperfusion injury significantly attenuated the serum and BAL cytokine concentrations, but did not change pulmonary neutrophil influx or histopathological alterations in response to iv LPS.