Temporal correlation of tumor necrosis factor-alpha release, upregulation of pulmonary ICAM-1 and VCAM-1, neutrophil sequestration, and lung injury in diet-induced pancreatitis

Abstract

Lung injury is a major cause of patient morbidity in acute pancreatitis. The purpose of this study was to examine the mechanism of pulmonary infiltration and lung injury in acute pancreatitis. Mice were fed a choline-deficient/ethionine-supplemented (CDE) diet for 144 hours to induce severe acute pancreatitis. Serum samples were collected for measurement of biochemical markers of disease and for the detection of tumor necrosis factor-alpha (TNF-α). Cell surface adhesion molecule expression was quantified by the sensitive radiolabeled dual monoclonal antibody technique. Neutrophil sequestration in lung tissue was measured by the myeloperoxidase assay. Lung injury was determined histologically and lung edema was assessed by wet/dry ratios. Pancreatic injury was demonstrated to occur in all CDE-fed mice, which developed significant hyperamylasemia and hypoglycemia by 48 hours ( P <0.0001). Serum TNF-α levels increased significantly by 48 hours over baseline values ( P <0.02). Expression of intracellular adhesion molecule (ICAM-1) in pulmonary endothelia was significantly increased above baseline by 30% at 48 hours ( P <0.02) and peaked at 120 hours by 100% ( P <0.0001). Vascular cellular adhesion molecule (VCAM-1) was constitutively expressed at baseline and was upregulated threefold by 48 hours ( P <0.0001). Neutrophil infiltration increased gradually 24 hours after ICAM-1 and VCAM-1 were upregulated with significant elevation of myeloperoxidase activity over baseline at 72 hours (7.2 ± 1.2 vs. 18.1 ± 2.2 activity units/gram tissue; P <0.05). Neutrophil infiltration peaked at 144 hours (26.24 ± 10.49 activity units/gram tissue P <0.0001), and its kinetics correlated with the onset and progression of morphologic injury as well as increased lung edema. These results show that acute pancreatitis is associated with a systemic release of inflammatory cytokines, followed by increased expression of pulmonary ICAM-1 and VCAM-1, neutrophil infiltration, and histologic lung injury. The adhesion molecule axis may be a potential target for practical intervention to ameliorate lung injury and morbidity in acute pancreatitis.