Specific pancreatic enzymes activate macrophages to produce tumor necrosisfactor-alpha: Role of nuclear factor kappa B and inhibitory kappa B proteins

The triggering events hv which mononuclear cells throughout the body are in duced to produce large amounts of cytokines during acute pancreatitis are u nclear. However; recent work in our laboratory demonstrated that three spec ific pancreatic enzymes (elastase, carboxypeptidase A, and lipase) induced dramatic tumor necrosis factor-alpha (TNF-alpha) protein production from ma crophages, whereas all others could not. This series of experiments was des igned to examine the second messenger system by which this occurs. The rat macrophage cell line NR8383 was incubated for 3 hours with elastase, carbox ypeptidase A, lipase, trypsin, or lipopolysaccharide (positive control). Ac tivation of nuclear factor kappa B (NF-kappa B) was demonstrated by electro phoretic mobility shift assay, presence of inhibitory kappa B alpha and bet a (I kappa B-alpha and I kappa B-beta) by Western blot analysis, and TNF-al pha protein production by enzyme-linked immunosorbent assay. Elastase, carb oxypeptidase A, and lipase induced degradation of I kappa B-beta (but not I kappa B-alpha), activation of NF-kappa B, and production of TNF-alpha prot ein, whereas inhibition of I kappa B with pyrrolidine dithiocarbamate atten uated this response. Trypsin was unable to elicit any of these responses. M acrophages can be induced by specific activated pancreatic enzymes-elastase , carboxypeptidase A and lipase-to produce TNF-alpha. This process is depen dent on I kappa B-beta degradation and NF-kappa B activation, suggesting th at these enzymes trigger this second messenger system through specific memb rane-bound receptors.