Experimental Chronic Pancreatitis Research Articles

Troglitazone reduces fibrosis formation and progression in an experimental model of chronic pancreatitis in mice

Trogftazone reduces fibrosis formation and progression in an experimental model of chronic pancreatitis in mice. Background: Peroxisome proliferator activated receptor gamma (PFARgamma) conu~:~ls growth, dilferentistion, and inflammation. Aim: To determine the influence of troglitazone, a figand for PPAR-gamma, on fibrosis and pancreatic damage in a mouse model of chronic pancreatitis. Methods: Mice received six hourly intraperitoneal injections ~4th 50 mg/kg cerulein (to induce pancreatins) or NACL (control), three times a week for six weeks. Seven weeks after the first injection all mice were sacrificed, Five groups were compared, i.e. A: NACL injections, B: NACL injections, chow' mixed with 0.2% troglitazone, C: cerulein iujections, D: cerulein injections, chow mLxed with troglitasone, E: cerulein injections, chow mixed with troglitazone during last 3 weeks only,. End points were pancreas weight, pancreas histology (abnormal architecture, glandular atrophy, pseudotubular complexes), collagen formation (sirius red staining to quantify fibrosis; image analysis), pancreas amylase and hydroxyproline content, TGF beta (in pancreas and plasma), and plasma soluble TNF receptor levels. The number of activated stellate cells was detected by immunohistochemistry. Results: Group C had developed chronic panereatitis after 7 weeks (all parameters P < 0.05, C vs At. Troglitazone given either for seven weeks or only for the last three weeks, reduced pancreatic damage (histology, amylase and hydroxyproline content), collagen formation, TGF beta and sTNF receptor levels and the number of activated stellate cells (P<O.05, D or E vs C; nonsignificant for D vs E). Conclusion: Troglitazone blocks activation of pancreatic stellate cells and reduces fibrosis formation and pancreatic damage in experimental chronic pancreatitis Troglitazone remains beneficial in a therapeutic setting when given after initial da:nage has been established.

The role of monocyte chemoattractant protein-1 in experimental chronic pancreatitis model induced by dibutyltin dichloride in rats.

Recently, dibutyltin dichloride (DBTC) was reported to induce pancreatic fibrosis within 28 days in rats, but it is not clear that the induced condition should be considered chronic pancreatitis. The aim of this study was to clarify whether the pancreatic fibrosis induced by DBTC can be regarded as chronic pancreatitis. Furthermore, we examined the relation of monocyte chemoattractant protein-1 (MCP-1) to the development of pancreatic fibrosis in this model. DBTC solution was injected into the right jugular vein in rats, and biochemical and histologic changes were measured at days 1, 3, 7, 14, and 28. Microscopically, inflammatory cell infiltration was evident in the pancreas at days 1 and 3, mononuclear cell infiltration was observed at days 7, 14, and 28, and pancreatic fibrosis was pronounced 7 days later. At day 28, interstitial fibrosis and atrophy of the gland and ductlike tubular complex had progressed. DBTC produced a significant decrease in the contents of pancreatic protein and amylase, whereas the pancreatic hydroxyproline content increased. Serum and pancreatic MCP-1 concentration significantly increased compared with the control group. Furthermore, the expression of PDGF mRNA in the pancreas increased following the MCP-1 elevation. These results suggest that this experimental model of pancreatic fibrosis induced by DBTC in rats was useful as a chronic pancreatitis model and that MCP-1 may play an important role in the development of pancreatic fibrosis.

Endogenous interleukin-10 modulates fibrosis and regeneration in experimental chronic pancreatitis

Interleukin (IL)-10, a potent anti-inflammatory cytokine, limits the severity of acute pancreatitis and downregulates transforming growth factor (TGF)-beta release by inflammatory cells on stimulation. Proinflammatory mediators, reactive oxygen species, and TGF-beta can activate pancreatic stellate cells and their synthesis of collagen I and III. This study evaluates the role of endogenous IL-10 in the modulation of the regeneration phase following acute pancreatitis and in the development of pancreatic fibrosis. IL-10 knockout (KO) mice and their C57BL/6 controls were submitted to repeated courses (3/wk, during 6 wk, followed by 1 wk of recovery) of cerulein-induced acute pancreatitis. TGF-beta(1) release was measured on plasma, and its pancreatic expression was assessed by quantitative RT-PCR and immunohistochemistry. Intrapancreatic IL-10 gene expression was assessed by semiquantitative RT-PCR, and intrapancreatic collagen content was assessed by picrosirius staining. Activated stellate cells were detected by immunohistochemistry. S phase intrapancreatic cells were marked using tritiated thymidine labeling. After repeated acute pancreatitis, IL-10 KO mice had more severe histological lesions and fibrosis (intrapancreatic collagen content) than controls. TGF-beta(1) plasma levels, intrapancreatic transcription, and expression by ductal and interstitial cells, as well as the number of activated stellate cells, were significantly higher. IL-10 KO mice disclosed significantly fewer acinar cells in S phase, whereas the opposite was observed for pseudotubular cells. Endogenous IL-10 controls the regeneration phase and limits the severity of fibrosis and glandular atrophy induced by repeated episodes of acute pancreatitis in mice.

Expression of hepatocyte growth factor, keratinocyte growth factor and their receptors in experimental chronic pancreatitis.

Hepatocyte (HGF) and Keratinocyte growth factors (KGF) are key factors of tissue organization and regeneration. These peptide growth factors and their receptors c-met and keratinocyte growth factor receptor (KGFR) are overexpressed in pancreatic cancer. Expression and localization of ligands and receptors were investigated during the development of experimental chronic pancreatitis. Chronic pancreatitis was induced in rats by intravenous injection of dibutyltin dichloride. One to 60 days after treatment, the expression of growth factors and receptors was analysed by competitive polymerase chain reaction, Western blot analysis and immunohistochemistry. HGF mRNA expression increased (10-fold) until days 7-14 followed by a decrease to control level. Expression of c-met mRNA constantly increased (15-fold). KGF and KGFR mRNA expression were increased after 14-28 days (5-fold) and then returned to control levels. mRNA expression patterns correlated with changes in the protein expression, whereas protein levels of KGF remained unchanged. Ligands were localized in mesenchymal cells and their receptors on epithelial cells. The significant increase of HGF and c-met expression suggests an essential role of this growth factor in the morphological changes during the development of chronic pancreatitis. Changes in the expression of KGF and KGFR are less pronounced.

Immune-mediated experimental chronic pancreatitis

Immune-mediated experimental chronic pancreatitis

Immune-mediated experimental chronic pancreatitis

Immune-mediated experimental chronic pancreatitis

Cytokine mRNA levels and lymphocyte infiltration in pancreatic tissue during experimental chronic pancreatitis induced by dibutyltin dichloride.

There is little information available regarding the role of inflammatory cells in the pathogenesis of chronic pancreatitis. Therefore, we analyzed the local cytokine profile and infiltrating lymphocytes in a rat model of chronic pancreatitis. Experimental pancreatitis was induced by a single intravenous application of dibultyltin dichloride (DBTC). During a time course of two months we observed the mRNA expression of cytokines using competitive RT-PCR. Lymphocytes were characterized by immunohistochemistry, FACS analysis, and the lymphocyte proliferation test. IL-1beta, IL-6, IL-5, and IL-10 were immediately up-regulated in the acute phase of disease, while lymphocyte-restricted expression of IL-2, IL-2R, and IFN-y was only found in the chronic course. Among the infiltrating lymphocytes, CD4+ cells dominated, but during the chronic process there was an increase of CD8+ cells, resulting in a reduced CD4/CD8 ratio. Mitogen-induced activation of isolated mesenteric lymph node cells increased during the chronic inflammation. Our results suggest that in experimental pancreatitis acute inflammatory reactions are followed by a T-lymphocyte-mediated process.

Expression of matrix metalloproteinases and their inhibitors in experimental chronic pancreatitis

Expression of matrix metalloproteinases and their inhibitors in experimental chronic pancreatitis

Activation of pancreatic stellate cells in experimental chronic pancreatitis in rats

Activation of pancreatic stellate cells in experimental chronic pancreatitis in rats

Microcirculation in Chronic Alcoholic Pancreatitis

Experimental chronic pancreatitis is associated with microcirculatory disturbances but can also be induced or aggravated by perfusion changes. Microcirculatory alterations in human chronic pancreatitis are poorly defined. In this clinical study we investigated pancreatic microcirculation in the normal human pancreas and in chronic pancreatitis by laser Doppler flowmetry. Laparotomy was performed on 13 patients with nonpancreatic disease and on nine patients with chronic alcoholic pancreatitis for pancreatic head resection. Blood flow was measured over the pancreatic head, the uncinate process, over the mesenteric vein, the pancreatic corpus, and over the pancreatic tail by laser Doppler flowmetry. Blood flow was highest in the head of a normal pancreas with a mean of 436 +/- 34 perfusion units (PU), 399 +/- 43 PU in the uncinate process, 286 +/- 30 PU in the pancreatic corpus, and 351 +/- 46 PU in the tail of the pancreas. In the normal pancreas, lowest blood flow was measured over the mesenteric vein (228 +/- 23 PU). In chronic pancreatitis, blood flow in the pancreas was significantly decreased across the whole pancreas (p < 0.01). Furthermore flow-wave pattern was altered in chronic pancreatitis as compared with the normal pancreas. The normal human pancreas has a spatial variation in blood flow, correlating with the pancreatic arterial blood supply. In the chronically inflamed human pancreas, blood flow is significantly diminished, with a lower flow toward the pancreatic head.

Morphological Study of Pancreatic Endocrine in an Experimental Chronic Pancreatitis with Diabetes Induced by Stress and Cerulein

The purpose of this study was to investigate the morphological changes in the islets observed in a new chronic pancreatitis model with diabetes induced by repetition of cerulein injection plus water-immersion stress in rats. The rats of this model were treated with water-immersion stress for 5 h and two intraperitoneal injections of 20 mug/kg body weight of cerulein once a week for 16 weeks. In the stress and cerulein group, 62% of the islets exhibited infiltration of mononucleated cells, and/or peri- and intrainsular fibrosis. On immunohistochemical study, some islets showed reduced density of the insulin immunoreactivity. The glucagon-producing cells decreased in number. With electron microscopy, various endocrine changes were observed, mainly in the B cells. The changes included scattered debris damage with reduction of secretary granules, and vesiculation of the endoplasmic reticulum. Numerous fibroblasts clustered around the islets, and proliferating collagen fibers invaded the islets. The microvascular changes consisted of bleeding and damage to the endothels. In the pancreas treated with stress alone or cerulein alone, significant endocrine damage was not observed. In conclusion, chronic repetitive treatment with stress and cerulein, together with poor islet circulation due to fibrosis and vascular changes, resulted in the endocrine cellular damage.

Radiologic investigations and pathologic results of experimental chronic pancreatitis in cats

The purpose of this study was to evaluate a variety of methods to induce chronic pancreatitis and its radiologic expression by experimentally inducing this condition in cats. Chronic inflammatory and fibrosing pancreatitis was produced in cats by intraductal injection of 1.5 mL of 94% ethanol in one group or by a combination of intraductal and intraparenchymal injection of ethanol together with partial obstruction of the main pancreatic duct to 70% of its original lumen by fixation of a small catheter in the papilla. For comparison, other cats underwent total obstruction of the main pancreatic duct. All groups, as well as untreated control cats (n = 3), underwent repeat laparotomy to obtain biopsy specimens. Cats with total obstruction showed progressing fibrosis with dilatation of ductules occasionally infiltrated with granulocytes. From 26 weeks on, acini and islets of Lnagerhans became atrophic. Radiographs showed progressive but diffuse dilatation of ducts, ductules, and side branches. Cats from the other two groups had interlobular inflammation and fibrosis with flattened and irregular ductular epithelium. Later, ductular proliferation occurred, interstitial inflammation subsided, and fibrosis increased. Radiographs showed very irregular ducts and ductules with stenosis and dilatation. From 26 weeks on, no substantial differences were observed between the cats who received only intraductal injection of ethanol and the cats who underwent the combination of procedures. The histopathologic and radiographic alterations that evolved from damage to the ductal epithelium in the cat resembled the features of chronic pancreatitis in humans and differed from those caused by total obstruction of the main pancreatic duct in cats.

Stenting does not decompress the pancreatic duct as effectively as surgery in experimental chronic pancreatitis

Background: In humans with chronic pancreatitis (CP), pancreatic interstitial pressure (IP) is elevated and pancreatic blood flow (PBF) is reduced. The efficacy of surgical decompression (SD) of the pancreatic duct (ie, pancreaticojejunostomy) is believed to be due to its ability to decrease IP and pancreatic vascular resistance (R p), which increases PBF. Pancreatic duct stenting (STE) also probably reduces IP and R p, which may explain its efficacy. The purpose of this study was to compare the efficacy of SD with STE. Methods: CP in cats was created by narrowing the main pancreatic duct. Six weeks later, CP and normal pancreata were isolated and perfused ex vivo under basal conditions and after secretin stimulation. In normal and CP glands, IP and perfusion pressure were measured and R p (U) was calculated. In two additional groups, the pancreatic duct was decompressed, either by stenting or by complete transection of the duct with a longitudinal capsulotomy. Results: In CP glands, IP and R p were increased and secretory output was markedly reduced compared with the normal (0.65 ± 0.30 mm Hg and 0.46 ± 0.04 U vs 3.90 ± 0.80 mm Hg and 1.68 ± 0.05 U; P < .05). Secretin administration (2 units) increased IP and R p in CP glands (6.60 ± 1.10 mm Hg and 2.87 ± 0.07 U; P < .05), but these values did not change in normal glands (0.81 ± 0.20 and 0.53 ± 0.03 U; NS). STE and SD decreased IP and R p in CP glands ( 2.20 ± 0.20 to 1.0 ± 0.40 mm Hg and 1.20 ± 0.015 to 0.90 ± 0.01 U, respectively; P < .05). Both methods prevented an increase of IP and R p after secretin administration. IP and R p decreased to a greater degree following SD, compared with STE ( P < .05). Conclusions: Both STE and SD decreased IP and R p in this experimental model of CP. However, SD was significantly more effective than STE. (Surgery 1998;124:561-7.)

Stenting does not decompress the pancreatic duct as effectively as surgery in experimental chronic pancreatitis

Stenting does not decompress the pancreatic duct as effectively as surgery in experimental chronic pancreatitis

Lymphocyte subsets in an experimental model of chronic pancreatitis in rats

The role of immunocompetent cells in chronic pancreatitis is poorly understood. Therefore, lymphocyte subsets were analyzed in pancreatic tissue, in peripheral blood, and in regional lymph nodes using an experimental chronic pancreatitis in rats. Methods: Pancreatitis was induced by intravenous application of dibutyltin dichloride (DBTC, 8mg/kg body weight). 5 rats per group were killed 1, 3, 5, 7, 14, 28, and 60 days after treatment. Pancreata were removed and examined immunohistochemicaUy with the APAAP technique. Peripheral blood and regional lymph nodes were obtained for isolation of lymphocytes followed by analysis of lymphocyte subsets using FACScan, Antibodies were directed to T lymphocytes, CD4+ helper T cells, CD8+ suppressor/cytotoxic T ceils, interleukin-2 receptor (CD25+), and B cells, Lymphocyte function was determined using the Concanavalin A (Con A) stimulated lymphocyte transformation assay with 3H-thymidine. Results: In DBTC-treated animals, we could demonstrate persistent infiltration of pancreatic tissue with lymphocytes. There was a predominance of CD4+ T cells compared to CD8+ T cells. However, CD8+ cells as well as CD25+ cells increased during the observation period. Number of B cells was low. During the observation period, no differences in the lymphocyte subsets in peripheral blood or in lymph nodes, were observed. Regarding lymphocyte function, we found significantly increased values of Con A induced lymphocyte transformation in regional lymph nodes in the course of pancreatitis. In peripheral blood, these changes could not be demonstrated. Conclusions: DBTC-pancreatitis was characterized by persistent infiltration of pancreatic tissue with CD4+ cells. CD8+ cells as well as activated lymphocytes increased. This indicates that suppressor/cytotoxic T cells play a role in the pathogenesis of experimental chronic pancreatitis. Regional lymph nodes were involved in the local inflammatory process. Supported by BMBF, FKZ 01/ZZ/9102

Nuclear factor kappa B activation in cerulein pancreatitis

IR 13-subunit was detected in electroph0retic lanes at 95 kD size. IR protein concentration in fed, saline-administered CP animals was significantly less than (1) in fed controls, and (2) in fasted, saline-administered CP's. PP administration had no significant effect on IR protein concentration in controls, but abolished the difference in IR protein in fed and fasted CP's. These data indicate that expression of hepatic IR is impaired in experimental chronic pancreatitis. This appears to result from a dramatic decrease and deficient maintenence of IR proteins during the fed state when maximal receptor internalization and degradation occur. This finding may reflect defective nutritional regulation of insulin receptor synthesis which is corrected by PP.

Polyunsatuted phosphatidylcholine effectively reduces collagen deposition in experimental chronic pancreatitis

Polyunsatuted phosphatidylcholine effectively reduces collagen deposition in experimental chronic pancreatitis

Pathophysiologic studies of experimental chronic pancreatitis in rats induced by injection of zein-oleic acid-linoleic acid solution into the pancreatic duct.

An experimental model of chronic pancreatitis was induced by a retrograde injection of a viscous solution consisting of zein-oleic acid-linoleic acid (0.05 ml/100 g body weight) into the rat pancreatic duct. Histologic and biochemical changes were investigated over a period of 6 months after induction of this model. The treated rats gained weight, but pancreatic weight decreased with time. Histologically, the widening of acinar lumen and cellular vacuolization occurred within 24 h at the parenchyma neighboring the small ducts filled with the injected solution. Degenerative parenchyma, interstitial edema, and inflammatory cell infiltration were pronounced 1 week later. Thereafter, duct-like tubular complex formation progressed, and the exocrine tissue exhibited marked atrophy of the gland with irregular fibrosis and fat replacement over a period of 6 months. Pancreatic contents of protein, amylase, DNA, and RNA markedly decreased, as did pancreatic weight, whereas hydroxyproline content increased. Oral administration of camostat did not affect pancreatic weight and contents of enzyme in this model. Urinary para-aminobenzoic acid (PABA) excretion in the BT-PABA test decreased to 54% at 6 weeks and 22% at 6 months. Although three quarters of pancreatic immunoreactive insulin (IRI) content was lost after 6 months, overt diabetes did not occur. The results suggest that an obstructive mechanism in the small ducts plays an important role in the genesis and development of chronic pancreatitis.

A new experimental chronic pancreatitis model in the dog: Effect of enzymatic replacement with an enteric-coated microsphere formulation (Eurobiol® 25.00 I.U.)

A new experimental chronic pancreatitis model in the dog: Effect of enzymatic replacement with an enteric-coated microsphere formulation (Eurobiol® 25.00 I.U.)

Ischaemia—Reperfusion Mechanisms in Acute Pancreatitis

The role of ischaemia in the pathogenesis of acute pancreatitis is unknown. Some experimental studies have shown that ischaemia has little effect on the pancreas, while others have found an association with pancreatic injury. Ischaemia-reperfusion damage has been well documented in other sites such as the intestine, cardiac muscle, and skeletal muscle. However, in the pancreas, injury is usually seen only after complete ischaemia, which is uncommon clinically. Experimental chronic pancreatitis is characterized by low pancreatic blood flow, low interstitial pH, and impaired pancreatic tissue oxygenation, which are all findings consistent with the ischaemia-reperfusion mechanisms. Acute pancreatitis is also associated with a reduction in pancreatic blood flow and evidence of free radical generation, similarly suggesting the possibility of ischaemia-reperfusion injury. Ethanol ingestion, which is commonly associated clinically with both chronic and acute pancreatitis, may itself contribute to an ischaemic-reperfusion injury. We have shown that administration of ethanol to cats decreases pancreatic blood flow and may also directly activate neutrophils. Further investigation is needed to determine whether or not these findings are also associated with an ischaemia-reperfusion injury.