Distant Organ Failure for Experimental Pancreatitis-Associated Porcine Pancreatic Elastase Is Responsible Pancreatitis : Endotoxin Contamination of Questioning Current Concepts in Acute

The systemic inflammatory response syndrome is responsible for pancreatitis-associated mortality. Recent in vitro and in vivo studies have suggested that pancreatic elastase is one missing link between the localized inflammatory process in the pancreas and distant organ dysfunction and failure. It has been shown that pancreatic elastase activates transcription factors, including NF-␬B, and induces TNF-␣ secretion in myeloid cells via TLRs. In this study we demonstrate that a highly purified low endotoxin pancreatic elastase preparation (El-UP) failed both to activate NF-␬B and to induce TNF-␣ release in RAW 264.7 cells and bone marrow-derived macrophages. In contrast, a less purified elastase preparation (El-IV) caused activation of NF-␬B and was able to induce TNF-␣ release at very low concentrations. These effects were sensitive to pretreatment of the cells with polymyxin B and were resistant to heat inactivation. Endotoxin activity as determined by the Limulus amebocyte lysate assay was >3 orders of magnitude lower in the low endotoxin elastase preparation (El-UP) compared with less purified elastase preparations (El-IV). In contrast to contaminated elastase or LPS, elastase free of contamination (El-UP) failed to induce elevated serum TNF-␣ levels or pulmonary neutrophil infiltration after i.p. application in mice and did not induce lethality when coinjected with D-galactosamine. Failure of low endotoxin elastase (El-UP) to induce proinflammatory effects in vivo and in vitro was not due to functional inactivity of the elastase preparation, as determined by elastase activity assay. These results question current concepts of direct proinflam-matory effects attributed to pancreatic elastase. I n the majority of cases, acute pancreatitis presents as a mild disease, with low mortality and morbidity. However, in 20% of cases, severe acute pancreatitis (SAP) 3 occurs, with a mortality of 15–20% (1–3). SAP is characterized by a systemic in-flammatory response syndrome (SIRS) that can lead to multiple distant organ failure, which is responsible for mortality. Systemic manifestations such as acute respiratory distress syndrome, hepatic injury, kidney failure, generalized capillary leakage, and acid/base disturbances are attributed to the propensity of the pancreas to propagate the initially localized and sterile inflammatory process regardless of the etiology of pancreatitis. By the intracellular processing of zymogen, different signaling pathways are activated within acinar cells (4). These early events lead to the secretion of chemokines and cytokines from acinar cells, followed by the recruitment and activation of inflammatory cells. Local cytokine production reaches the liver via the portal system and subsequently the lung and spleen, where …