ABSTRACT
Matrix metalloproteinases (MMPs) are the proteases involved in the degradation of the extracellular matrix. MMP-1 is thought to be one of the key enzymes in fibrolysis, a process closely related to tissue remodeling. In the present study, we investigated MMP-1 secretion from human pancreatic periacinar myofibroblasts in response to pro-inflammatory cytokines IL-1beta and TNF-alpha. We also attempted to clarify the intracellular signaling pathways mediating the cytokine-induced MMP-1 secretion. MMP-1 secretion was measured by an enzyme-linked immunosorbent assay. MMP-1 molecules were analyzed by Western blotting. MMP-1 mRNA expression was evaluated by Northern blotting. IL-1l and TNF-alpha stimulated the MMP-1 secretion in a dose- and time-dependent manner. Ninety percent of MMP-1 was secreted as inactive form (pro-MMP-1). The effects of IL-1beta and TNF-alpha were significantly inhibited by PD98059 MEK/ERK inhibitor). In contrast, SB203580 (p38 MAPK inhibitor), GF109203X (PKC inhibitor), and PDTC (NF-kappaB inhibitor) did not alter the MMP-1 secretion induced by IL-1beta and TNF-alpha. These effects were also observed at them RNA level. In conclusion, in human pancreatic periacinar myofibroblasts, MMP-1 secretion was regulated by the pro-inflammatory cytokines via the MEK/ERK cascade. Thus, human pancreatic periacinar myofibroblasts may play an important role in the remodeling of damaged pancreatic tissue in chronic pancreatitis via MMP-1 secretion.
Subject(s)
Enzyme Inhibitors/pharmacology , Fibroblasts/enzymology , Flavonoids/pharmacology , Interleukin-1/metabolism , Matrix Metalloproteinase 1/metabolism , Pancreas/metabolism , Proline/analogs & derivatives , Tumor Necrosis Factor-alpha/metabolism , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Blotting, Northern , Blotting, Western , Enzyme-Linked Immunosorbent Assay , Fibroblasts/drug effects , Humans , Imidazoles/pharmacology , Indoles/pharmacology , Kinetics , MAP Kinase Signaling System/drug effects , Maleimides/pharmacology , Mitogen-Activated Protein Kinases/antagonists & inhibitors , NF-kappa B/antagonists & inhibitors , Pancreas/cytology , Pancreas/enzymology , Proline/pharmacology , Pyridines/pharmacology , Thiocarbamates/pharmacologyABSTRACT
Pancreatic periacinar myofibroblasts are considered to be therapeutic targets for the suppression of acute pancreatitis. To elucidate the mechanisms mediating the therapeutic actions of somatostatin on acute pancreatitis, we investigated how somatostatin affects the tumor necrosis factor (TNF)-alpha-induced interleukin (IL)-6 and IL-8 secretion from pancreatic myofibroblasts. Cytokine secretion was determined by enzyme-linked immunosorbent assay (ELISA) and Northern blotting. Nuclear factor (NF)-kappaB DNA-binding activity was evaluated by electrophoretic mobility shift assay (EMSAs). The expression of somatostatin receptor (SSTR) mRNA was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). Somatostatin dose-dependently inhibited the TNF-alpha-induced IL-6 secretion. In comparison, the effects on IL-8 secretion were modest. Northern blot analysis demonstrated that somatostatin decreased the TNF-alpha-induced IL-6 mRNA expression, and that this effect was completely blocked by the somatostatin antagonist cyclo-somatostatin. Furthermore, somatostatin suppressed TNF-alpha-induced NF-kappaB activation. These cells bear SSTR subtypes 1 and 2. Somatostatin down-regulated the TNF-alpha-induced IL-6 secretion in human pancreatic periacinar myofibroblasts. These findings suggest that some of the therapeutic actions of somatostatin on acute pancreatitis might be mediated by reducing local IL-6 secretion in the pancreas.
Subject(s)
Interleukin-6/metabolism , Pancreas/drug effects , Pancreatitis/drug therapy , Somatostatin/pharmacology , Tumor Necrosis Factor-alpha/antagonists & inhibitors , Acute Disease , Blotting, Northern , Fibroblasts/drug effects , Fibroblasts/metabolism , Gene Expression Regulation , Humans , Interleukin-6/genetics , Interleukin-8/metabolism , NF-kappa B/metabolism , Pancreas/metabolism , Pancreatitis/metabolism , Receptors, Somatostatin/genetics , Receptors, Somatostatin/metabolism , Tumor Necrosis Factor-alpha/metabolismABSTRACT
INTRODUCTION: Ws/Ws rats have a small deletion of the c-kit gene and are deficient in both mucosal-type mast cells and connective tissue-type mast cells. AIM: To investigate the role of pancreatic mast cells in the development of experimental closed duodenal loop (CDL)-induced pancreatitis using Ws/Ws rats. METHODOLOGY: Pancreatitis was induced by the CDL technique for 5 and 12 hours, and the subsequent ascites volume, wet pancreatic weight, pancreatic myeloperoxidase activities, and serum amylase levels were evaluated. The pancreatic tissue damage was also evaluated histologically. RESULTS: The CDL technique induced equally severe ascites, pancreatic edema and hyperemia, and hyperamylasemia in the Ws/Ws versus the control (+/+) rats. The microscopic mucosal damage score was also equivalent in the Ws/Ws and control (+/+) rats, and there were no significant differences in mucosal myeloperoxidase activity between the Ws/Ws and control (+/+) rats. CONCLUSION: These results indicate that mast cells may not be crucial for the development of CDL-induced pancreatitis.
Subject(s)
Duodenum/surgery , Mast Cells/physiology , Pancreatitis/etiology , Pancreatitis/pathology , Amylases/blood , Animals , Ascites/pathology , Constriction , Disease Models, Animal , Edema/etiology , Gene Deletion , Hyperemia/etiology , Male , Mucous Membrane/enzymology , Mucous Membrane/pathology , Organ Size , Pancreas/enzymology , Pancreas/pathology , Peroxidase/metabolism , Proto-Oncogene Proteins c-kit/genetics , Rats , Rats, Mutant Strains , Time FactorsABSTRACT
There is increasing evidence that IL-6 plays an important role in the pathophysiology of acute pancreatitis via its broad proinflammatory actions. To identify the local biosynthetic site for IL-6 in human pancreas, we investigated IL-6 secretion in human pancreatic periacinar myofibroblasts. IL-6 secretion was determined by ELISA and Northern blotting. The activation of NF-kappaB was assessed by EMSA. The activation of mitogen-activated protein kinase (MAPK) was assessed by immunoblotting. IL-6 secretion was rapidly induced by IL-17, IL-1beta, and TNF-alpha. EMSAs demonstrated that IL-17, IL-1beta, and TNF-alpha induced NF-kappaB activation within 1.5 h after stimulation, and a blockade of NF-kappaB activation by the pyrrolidine derivative of dithiocarbamate and tosyl-phe-chloromethylketone markedly reduced the IL-17-, IL-1beta-, or TNF-alpha-induced IL-6 gene expression. Furthermore, IL-17, IL-1beta, and TNF-alpha induced a rapid activation of extracellular signal-related kinase p42/44 and p38 MAPKs, and specific MAPK inhibitors (SB203580, PD98059, and U0216) significantly reduced IL-17-, IL-1beta-, or TNF-alpha-induced IL-6 secretion, indicating the role of MAPKs in the induction of IL-6. The combination of either IL-17 plus IL-1beta or IL-17 plus TNF-alpha enhanced IL-6 secretion and IL-6 mRNA expression; in particular, the effects of IL-17 plus TNF-alpha were much stronger than those induced by IL-17 plus IL-1beta. TNF-alpha-induced IL-6 mRNA degraded rapidly at any concentrations, and the combination of IL-17 and TNF-alpha markedly enhanced IL-6 mRNA stability. This indicates that the effects of IL-17 plus TNF-alpha were regulated at the post-transcriptional level. In conclusion, pancreatic periacinar myofibroblasts secreted a large amount of IL-6 in response to proinflammatory cytokines. These cells might play an important role in the pathogenesis of acute pancreatitis via IL-6 secretion.
