PANCREATIC ASCITES AS A POWERFUL INDUCER OF INFLAMMATORY CYTOKINES - THE ROLE OF KNOWN VS UNKNOWN FACTORS

Objectives: To determine if pancreatic ascites will induce interleukin 1 beta (IL-1 beta) or tumor necrosis factor alpha (TNF-alpha) product ion outside the pancreas and examine the possible components responsib le. Design: Severe pancreatitis was induced in rats (n=30) by pancreat ic duct infusion with 4% glycodeoxycholic acid; pancreatic ascites was collected 18 hours later. In vitro studies used quiescent murine sple nic or pulmonary macrophages (10(5)/mL) which were exposed to media al one (control), trypsin, chymotrypsin, cathepsin-B, 20% ascites (vol/vo l), 50% ascites, or endotoxin (lipopolysaccharide, 10 mu g/mL, positiv e control) for 4 hours. Subsequently, pancreatic ascites was cultured for bacteria and assayed for endotoxin and cytokines (interleukin 1, i nterleukin 6, interleukin 8, TNF-alpha, or interferon gamma). The expe riments were then repeated using 20% and 50% ascites that was sterile and cytokine-free (SCF ascites). In vivo studies used 100% (n=8) or 50 % (n=12) SCF ascites or normal rat serum (control, n=12) for a 10-seco nd pulmonary lavage (100 mu L) in adult mice, with lungs collected at 6 hours for cytokine gene analysis. Setting: Surgical basic science re search laboratory. Main Outcome Measures: Interleukin 1 beta and TNF-a lpha gene induction was assessed by quantitative competitive reverse-t ranscription polymerase chain reaction and cytokine protein production was determined by enzyme-linked immunosorbent assay. Results: Macroph ages responded to untested and SCF ascites in a dose-dependent fashion , with a multifold increase in both IL-1 beta and TNF-alpha messenger RNA (mRNA) and protein, which was often more potent than lipopolysacch aride. Expression of IL-1 beta and TNF-alpha mRNA could not be induced by trypsin, chymotrypsin, or cathepsin-B. All animals undergoing lava ge with 100% SCF ascites died within 2 hours, while those undergoing l avage with 50% SCF ascites showed a multifold increase in pulmonary IL -1 beta and TNF-alpha mRNA. Conclusions: Pancreatic ascites contains f actors that are capable of inducing IL-1 beta and TNF-alpha production in vitro and in vivo. This effect cannot be reproduced by activated d igestive enzymes and is propagated despite the absence of known induce rs of cytokines such as bacteria, endotoxin, or other inflammatory cyt okines.