Lipid peroxidation inhibition reduces NF-kappaB activation and attenuates cerulein-induced pancreatitis

Increased lipid peroxidation, enhanced nuclear factor kappa-B (NF-kappaB) activation and augmented tumor necrosis factor-alpha (TNF-alpha) production have been implicated in cerulein-induced pancreatitis. We investigated whether lipid peroxidation inhibition might reduce NF-kappaB activation and the inflammatory response in cerulein-induced pancreatitis. Male Sprague-Dawley rats of 230-250g body weight received administration of cerulein (80 microg/kg s.c. for each of four injections at hourly intervals). A control group received four s.c. injections of 0.9% saline at hourly intervals. Animals were randomized to receive either raxofelast, an inhibitor of lipid peroxidation (20 mg/kg i.p. administered with the first cerulein injection) or its vehicle (1 ml/kg of a 10% DMSO/NaCl solution). All these rats were sacrificed 2 h after the last injection of either cerulein or its vehicle. Raxofelast administration (20 mg/kg i.p. with the first cerulein) significantly reduced malondialdehyde (MDA) levels, an index of lipid peroxidation (CER + DMSO = 3.075 +/- 0.54 micromol/g; CER + raxofelast = 0.693 +/- 0.18 micromol/g; p < 0.001), decreased myeloperoxidase (MPO) activity (CER + DMSO = 22.2 +/- 3.54 mU/g; CER + raxofelast = 9.07 +/- 2.05 mU/g, p < 0.01), increased glutathione levels (GSH) (CER + DMSO = 5.21 +/- 1.79 micromol/g; CER + raxofelast = 15.71 +/- 2.14 micronol/g; p < 0.001), and reduced acinar cell damage evaluated by means of histology and serum levels of both amylase (CER + DMSO = 4063 +/- 707.9 U/l; CER + raxofelast = 1198 +/- 214.4 U/l; p < 0.001), and lipase (CER + DMSO = 1654 +/- 330 U/l; CER + raxofelast = 386 +/- 118.2 U/l; p < 0.001), Furthermore, raxofelast reduced pancreatic NF-kappaB activation and the TNF-alpha mRNA levels and tissue content of mature protein in the pancreas. Indeed, lipid peroxidation inhibition might be considered a potential therapeutic approach to prevent the severe damage in acute pancreatitis.     

Adrenomedullin reduces the severity of cerulein-induced acute pancreatitis

We investigated the effect of Adrenomedullin (AM) on cerulein-induced acute pancreatitis in rats. AM treatment (100 ng/kg per rat, subcutaneous) after one hour of cerulein injection reduced the plasma amylase levels, pancreatic weight, pancreatic malondialdehyde (MDA) levels, and the severity of the lesions microscopically. These data suggest that AM has a protective effect on cerulein-induced acute pancreatitis. These could be due to anti-inflammatory properties of AM, inhibition of proinflammatory cytokine secretion, reducing the endothelial permeability increased by reactive oxygen species, endotoxins or cytokines.     

Alpha-melanocyte stimulating hormone has beneficial effects on cerulein-induced acute pancreatitis

We investigated the effect of alpha-melanocyte stimulating hormone (alpha-MSH) on cerulein induced acute pancreatitis in rats. alpha-MSH treatment (50 microg per rat, intraperitoneally) prior to cerulein reduced the plasma amylase level, pancreatic weight, pancreatic myeloperoxidase activity and the severity of the lesions microscopically. These data suggest that alpha-MSH has a protective effect on cerulein-induced acute pancreatitis and this effect could be attributed, at least in part, to decreased tissue leukocyte infiltration and thus, to decreased pro-inflammatory cytokine production and/or oxygen- and nitrogen-derived reactive metabolite release.     

Protective effect of central thyrotropin-releasing hormone analog on cerulein-induced acute pancreatitis in rats

Central neuropeptides play a role in many physiological functions through the autonomic nervous system. We have recently demonstrated that central injection of a thyrotropin-releasing hormone (TRH) analog increases pancreatic blood flow through vagal and nitric oxide-dependent pathways. In this study, the central effect of a TRH analog on experimental acute pancreatitis was investigated in rats. Acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 microg/kg) at 1-h interval. Either stable TRH analog, RX 77368 (5-100 ng), or saline was injected intracisternally 15 min before the first cerulein injection under ether anesthesia. Serum amylase level was measured before and 5 h after the first cerulein injection. Pancreatic wet/dry weight ratio and histological changes were also evaluated. Intracisternal TRH analog inhibited cerulean-induced elevation of serum amylase level, increase in pancreatic wet/dry weight ratio and pancreatic histological changes, such as interstitial edema, inflammation and vacuolization. The pancreatic cytoprotection induced by central TRH analog was abolished by subdiaphragmatic vagotomy and N(G)-nitro-L-arginine-methyl ester (L-NAME), but not by 6-hydroxydopamine (6-OHDA). Intravenous administration of the TRH analog did not influence cerulein-induced acute pancreatitis. These results indicate that the TRH analog acts in the central nervous system to protect against acute pancreatitis through vagal and nitric oxide-dependent pathways.     

Chemokine receptor CCR5 deficiency exacerbates cerulein-induced acute pancreatitis in mice

Acute pancreatitis (AP) is an inflammatory disease involving the production of different cytokines and chemokines and is characterized by leukocyte infiltration. Because the chemokine receptor CCR5 and its ligands [the CC chemokines CCL3/MIP-1alpha, CCL4/MIP-1beta, and CCL5/regulated upon activation, normal T cell expressed and secreted (RANTES)] regulate leukocyte chemotaxis and activation, we investigated the expression of CCR5 ligands and the role of CCR5 and its ligands in experimental AP in mice. AP was induced by hourly intraperitoneal injections of cerulein in CCR5-deficient (CCR5(-/-)) or wild-type (WT) mice. Induction of AP by cerulein resulted in an early increase of pancreatic CCL2, CCL3, and CCL4 mRNA expression, whereas CCL5 mRNA expression occurred later. CCR5(-/-) mice developed a more severe pancreatic injury than WT mice during cerulein-induced AP, as assessed by a more pronounced increase in serum amylase and lipase levels and by more severe pancreatic edema, inflammatory infiltrates (mainly neutrophils), and necrosis. CCR5(-/-) mice also exhibited increased production of CCL2/MCP-1, CCL3/MIP-1alpha, and CCL4/MIP-1beta during the course of cerulein-induced AP. In vivo simultaneous neutralization of CC chemokines with monoclonal antibodies in CCR5(-/-) mice reduced the severity of cerulein-induced AP, indicating a role of CC chemokines in exacerbating the course of AP in the absence of CCR5. Moreover, simultaneous neutralization of CCR5 ligands in WT mice also reduced the severity of cerulein-induced AP. In conclusion, lack of the chemokine receptor CCR5 exacerbates experimental cerulein-induced AP and leads to increased levels of CC chemokines and a more pronounced pancreatic inflammatory infiltrate, suggesting that CCR5 expression can modulate severity of AP.     

Chemopreventive effects of resveratrol in a rat model of cerulein-induced acute pancreatitis

In the past decades, a greater understanding of acute pancreatitis has led to improvement in mortality rates. Nevertheless, this disease continues to be a health care system problem due to its economical costs. Future strategies such as antioxidant supplementation could be very promising, regarding to beginning and progression of the disease. For this reason, this study was aimed at assessing the effect of exogenous administration of resveratrol during the induction process of acute pancreatitis caused by the cholecystokinin analog cerulein in rats. Resveratrol pretreatment reduced histological damage induced by cerulein treatment, as well as hyperamylasemia and hyperlipidemia. Altered levels of corticosterone, total antioxidant status, and glutathione peroxidase were significantly reverted to control levels by the administration of resveratrol. Lipid peroxidation was also counteracted; nevertheless, superoxide dismutase enzyme was overexpressed due to resveratrol pretreatment. Related to immune response, resveratrol pretreatment reduced pro-inflammatory cytokine IL-1β levels and increased anti-inflammatory cytokine IL-10 levels. In addition, pretreatment with resveratrol in cerulein-induced pancreatitis rats was able to reverse, at least partially, the abnormal calcium signal induced by treatment with cerulein. In conclusion, this study confirms antioxidant and immunomodulatory properties of resveratrol as chemopreventive in cerulein-induced acute pancreatitis.     

Proteome analysis of rat pancreatic acinar cells: implication for cerulein-induced acute pancreatitis

Cerulein pancreatitis was shown to be one of the best characterized models for acute pancreatitis. High doses of cerulein induce a dysregulation of the digestive enzyme production and cytoplasmic vacuolization and the death of acinar cells, edema formation, and an infiltration of inflammatory cells into the pancreas, which are similar symptoms shown in human acute pancreatitis. The present study aims to determine the differentially expressed proteins in cerulein-treated pancreatic acinar cells as an in vitro model for acute pancreatitis. Pancreatic acinar AR42J cells were treated with 10(-8) M cerulein for 24 h. The changed protein patterns separated by two-dimensional electrophoresis using pH gradients of 5-8 were conclusively identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry analysis of the peptide digests. Five differentially expressed proteins (heat shock protein 90, mitochondrial ATP synthase beta chain precursor, tubulin beta chain, 3-mercaptopyruvate sulfurtransferase, mitochondrial ATP synthase subunit D) were identified in cerulein-treated AR42J cells. These proteins are related to cellular stress such as reactive oxygen species, cytoskeletal function, and cell signaling. In conclusion, the differentially expressed proteins will provide valuable information to understand the pathophysiologic mechanism of acute pancreatitis and may be useful for prognostic indices of acute pancreatitis.     

Differential effects of saralasin and ramiprilat,the inhibitors of renin-angiotensin system,on cerulein-induced acute pancreatitis

Acute pancreatitis is an inflammatory disease characterized by pancreatic tissue edema, acinar cell necrosis, hemorrhage and inflammation of the damaged gland. It is believed that acinar cell injury is initiated by the activation of digestive zymogens inside the acinar cells, leading finally to the autodigestion of the pancreas. Previous study in our laboratory demonstrated that cerulein-induced acute pancreatitis was associated with an up-regulation of local renin-angiotensin system (RAS) in rat pancreas. Therefore, the utilization of RAS inhibitors may provide a novel and alternative treatment for acute pancreatitis. By means of a rat model of cerulein-induced acute pancreatitis, results from the present study showed that an intravenous injection of saralasin, an antagonist for angiotensin II receptors, at a dose of 40 microg/kg 30 min before the induction of acute pancreatitis significantly attenuated pancreatic edema. Results from the biochemical measurements showed that pretreatment with saralasin at a dose of 20 microg/kg markedly reduced pancreatic injury, as evidenced by the decreased activities of alpha-amylase and lipase in plasma. However, the same recipe of ramiprilat, a specific inhibitor for angiotensin-converting enzyme, at a dose of 20 microg/kg did not provide any protective effect against acute pancreatitis. On the contrary, pretreatment with ramiprilat at a dose 40 microg/kg enhanced cerulein-induced pancreatic injury. Results from histopathological analysis of these RAS inhibitors further confirmed with those results as obtained from biochemical analysis. These data indicate that administration of saralasin but not ramiprilat could be protective against acute pancreatitis and that activation of pancreatic RAS in acute pancreatitis may play a role in pancreatic tissue injury.     

Dysregulation of the calpain-calpastatin system plays a role in the development of cerulein-induced acute pancreatitis in the rat

Calpain, a calcium-dependent cytosolic cysteine protease, is implicated in a multitude of cellular functions but also plays a role in cell death. Recently, we have shown that two ubiquitous isoforms, termed micro-calpain and m-calpain, are expressed in rat pancreatic acinar cells and that calcium ionophore-induced calpain activation leads to acinar cell injury. On the basis of these observations, we have now investigated the role of both calpain forms and the endogenous calpain inhibitor calpastatin in acute pancreatitis. After treatment of rats either without or with calpain inhibitor Z-Val-Phe methyl ester (ZVP; 60 mg/kg i.p.), pancreatitis was induced by cerulein injections (10 microg/kg i.p.; 5 times at hourly intervals). Calpain activation and calpastatin expression in the pancreatic tissue were studied by Western blot analysis. Pancreatic injury was assessed by plasma amylase activity, pancreatic wet/dry weight ratio (edema), histological and electron-microscopic analyses, as well as fluorescence labeling of actin filaments. Cerulein caused an activation of both micro-calpain and m-calpain, accompanied by degradation of calpastatin. Prophylactic administration of ZVP reduced the cerulein-induced calpain activation but had no effect on calpastatin alterations. In correlation to the diminished calpain activity, the severity of pancreatitis decreased as indicated by a decline in amylase activity (P < 0.01), pancreatic edema formation (P < 0.05), histological score for eight parameters (P < 0.01), and actin filament alterations. Our findings support the hypothesis that dysregulation of the calpain-calpastatin system may play a role in the onset of acute pancreatitis.     

Changes in the expression and dynamics of SHP-1 and SHP-2 during cerulein-induced acute pancreatitis in rats

Protein tyrosine phosphatases (PTPs) are important regulators of cell functions but data on different PTP expression and dynamics in acute pancreatitis (AP) are very scarce. Additionally, both c-Jun N-terminal kinases (JNK) and extracellular signal-regulated kinases (ERK1/2), together with intracellular cAMP levels in inflammatory cells, play an essential role in AP. In this study we have detected an increase in PTP SHP-1 and SHP-2 in the pancreas at the level of both protein and mRNA as an early event during the development of Cerulein (Cer)-induced AP in rats. Nevertheless, while SHP-2 protein returned to baseline levels in the intermediate or later phases of AP, SHP-1 protein expression remained increased throughout the development of the disease. The increase in SHP-2 protein expression was associated with changes in its subcellular distribution, with higher percentages located in the fractions enriched in lysosomes+mitochondria or microsomes. Furthermore, while the increase in SHP-2 protein was also observed in sodium-taurocholate duct infusion or bile-pancreatic duct obstruction AP, that of SHP-1 was specific to the Cer-induced model. Neutrophil infiltration did not affect the increase in SHP-1 protein, but favoured the return of SHP-2 protein to control levels, as indicated when rats were rendered neutropenic by the administration of vinblastine sulfate. Inhibition of JNK and ERK1/2 with SP600125 pre-treatment further increased the expression of both SHP-1 and SHP-2 proteins in the early phase of Cer-induced AP, while the inhibition of type IV phosphodiesterase with rolipram only suppressed the increase in SHP-2 protein expression during the same phase. Our results show that AP is associated with increases in the expression of SHP-1 and SHP-2 and changes in the dynamics of SHP-2 subcellular distribution in the early phase of Cer-induced AP. Finally, both JNK and ERK1/2 and intracellular cAMP levels are able to modulate the expression of these PTPs.     

Specific type IV phosphodiesterase inhibitor ameliorates cerulein-induced pancreatitis in rats

BACKGROUND AND AIMS: Type IV phosphodiesterase is a key enzyme to metabolize intracellular adenosine 3',5'-cyclic monophosphate (cAMP) expressed in inflammatory cells. The specific type IV phosphodiesterase inhibitor that increases intracellular cAMP is known to be potent suppressor of proinflammatory cytokines. However, the effect of phosphodiesterase inhibitors on the development of pancreatitis has not been well understood. In the present study, we examined the effect of a specific type IV phosphodiesterase inhibitor on experimentally induced pancreatitis. METHODS: Severity of cerulein-induced pancreatitis and pancreatic proinflammatory cytokine levels were studied with or without pretreatment with a specific type IV phosphodiesterase inhibitor (rolipram) in Sprague-Dawley rats. RESULTS: Administration of rolipram clearly ameliorated severity of pancreatitis evaluated by edema, serum amylase (P<0.05), and lipase levels (P<0.05) in rats. Also, the level of pancreatic proinflammatory cytokine (interleukin-1beta (IL-1beta)) was significantly reduced when rats were treated with rolipram prior cerulein injection (P<0.05). CONCLUSIONS: Our results demonstrated that intracellular cAMP and pancreatic proinflammatory cytokine level, which are regulated by type IV phosphodiesterase, might play an important role in the pathogenesis of acute pancreatitis.     

Piperine ameliorates the severity of cerulein-induced acute pancreatitis by inhibiting the activation of mitogen activated protein kinases

Piperine is a phenolic component of black pepper (Piper nigrum) and long pepper (Piper longum), fruits used in traditional Asian medicine. Our previous study showed that piperine inhibits lipopolysaccharide-induced inflammatory responses. In this study, we investigated whether piperine reduces the severity of cerulein-induced acute pancreatitis (AP). Administration of piperine reduced histologic damage and myeloperoxidase (MPO) activity in the pancreas and ameliorated many of the examined laboratory parameters, including the pancreatic weight (PW) to body weight (BW) ratio, as well as serum levels of amylase and lipase and trypsin activity. Furthermore, piperine pretreatment reduced the production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 during cerulein-induced AP. In accordance with in vivo results, piperine reduced cell death, amylase and lipase activity, and cytokine production in isolated cerulein-treated pancreatic acinar cells. In addition, piperine inhibited the activation of mitogen-activated protein kinases (MAPKs). These findings suggest that the anti-inflammatory effect of piperine in cerulein-induced AP is mediated by inhibiting the activation of MAPKs. Thus, piperine may have a protective effect against AP.     

Interleukin-22 ameliorates cerulein-induced pancreatitis in mice by inhibiting the autophagic pathway

Pancreatitis occurs when digestive enzymes are activated in the pancreas. Severe pancreatitis has a 10-30% mortality rate. No specific treatments for pancreatitis exist now. Here, we discovered that interleukin-22 (IL-22) may have therapeutic potential in treating acute and chronic pancreatitis. Wild-type and IL-22 knockout mice were equally susceptible to cerulein-induced acute and chronic pancreatitis, whereas liver-specific IL-22 transgenic mice were completely resistant to cerulein-induced elevation of serum digestive enzymes, pancreatic necrosis and apoptosis, and inflammatory cell infiltration. Treatment of wild-type mice with recombinant IL-22 or adenovirus IL-22 markedly attenuated the severity of cerulein-induced acute and chronic pancreatitis. Mechanistically, we show that the protective effect of IL-22 on pancreatitis was mediated via the induction of Bcl-2 and Bcl-X(L), which bind to Beclin-1 and subsequently inhibit autophagosome formation to ameliorate pancreatitis. In conclusion, IL-22 ameliorates cerulein-induced pancreatitis by inhibiting the autophagic pathway. IL-22 could be a promising therapeutic drug to treat pancreatitis.     

Fatiguing exercise reduces DNA binding activity of NF-kappaB in skeletal muscle nuclei.

This study tested the hypothesis that skeletal muscle contraction activates nuclear factor-kappaB (NF-kappaB), a putative regulator of muscle protein breakdown. Muscle biopsies were obtained from the vastus lateralis of healthy humans before, immediately after, and 1 h after fatiguing resistance exercise of the lower limbs. Biopsies were analyzed for nuclear NF-kappaB DNA binding activity by using electrophoretic mobility shift assay. NF-kappaB activity, measured immediately after exercise, was less than preexercise activity; after 1-h recovery, activity returned to preexercise levels. In follow-up studies in adult mice, basal NF-kappaB activity varied among individual muscles. NF-kappaB activity in diaphragm fiber bundles was decreased after a 10-min bout of fatiguing tetanic contractions in vitro. NF-kappaB activity in soleus was increased by 12 days of unloading by hindlimb suspension; this increase was reversed by 10 min of fatiguing exercise. These data provide no support for our original hypothesis. Instead, acute fatiguing exercise appears to decrease NF-kappaB activity in muscle under a variety of conditions.     

Inhibitory activity of polyhydroxycarboxylate chelators against recombinant NF-kappaB p50 protein-DNA binding

The inhibitory effect of 7,8-dihydroxy-4-methylcoumarin (7,8-DHMC), 5,7-dihydroxy-4-methylcoumarin (5,7-DHMC), and gallic acid on the DNA binding of recombinant p50 protein and their interaction with zinc ion were studied. Electrophoretic mobility shift assay (EMSA) using p50 and biotin labeled DNA has shown that gallic acid is more effective than the dihydroxycoumarins in inhibiting the p50-DNA binding. Molecular modeling studies suggest an explanation for these observations. Effect of the addition of zinc after p50-DNA-binding inhibition by gallic acid was also studied. Chemical speciation and formation constant studies show that gallic acid forms a more stable 1:1 complex with zinc ion in comparison to the dihydroxycoumarins.     

Proteomic analysis of the soluble and the lysosomal+mitochondrial fractions from rat pancreas: Implications for cerulein-induced acute pancreatitis

Alterations in protein expression within the initiation phase of acute pancreatitis (AP) might play an important role in the development of this disease, lysosomes being involved in its pathophysiology. The use of pancreatic subcellular fractions in proteomic analysis, simplifies protein maps and helps in the identification of new protein changes and biomarkers characterizing tissue damage. The present study aims to determine the differentially expressed acidic proteins in the pancreatic soluble and lysosomal+mitochondrial (L+M) fractions from rats during the early phase of the experimental model of cerulein (Cer)-induced AP. Subcellular pancreatic extracts from diseased and control rats were analyzed by 2-DE (3-5.6 pH range) and MALDI-TOF/TOF MS. Comparative analysis afforded the conclusive identification of 13 (soluble fraction) and 7 (L+M fraction) proteins or protein fragments ocurring in different amounts between diseased and control pancreas, some of them being newly described in AP. In the soluble fraction, we detected changes related to inflammation and apoptosis (α1-inhibitor-3, α-1 antitrypsin, α-1 macroglobulin, haptoglobin, STRAP), oxidative stress and stress response (peroxiredoxin-2, thioredoxin-like 1, GRP94/TRA1, heat shock cognate 71kDa protein), digestive proteases (elastase 3B), serine protease inhibition (serpins B6 and A3L) and translation processes (EF 1-δ). In the L+M fraction, we detected changes mainly related to energy generation or cellular metabolism (ATP synthase β subunit, chymotrypsinogen B, triacylglycerol lipase), cell redox homeostasis (iodothyronine 5′monodeiodinase) and digestive proteases (carboxypeptidase B1). The data should provide valuable information for unraveling the early pathophysiologic mechanisms of Cer-induced AP.     

Diagnostic importance of determining leucine aminotransferase activity in acute pancreatitis

It has been experimentally and clinically established that the determination of leucine-aminotransferase activity in the blood serum and abdominal exudate may serve as a marker for the early determination of pancreonecrosis and edematous (serous) pancreatitis.     

Effect of somatostatin on bile-induced acute hemorrhagic pancreatitis in the dog.

In 21 female Beagle dogs an experimental pancreatitis was induced by injection of bile into the pancreatic duct system. Beside controls, dogs received 62.5 micrograms/h cyclic somatostatin (SRIF) a continuous i.v. infusion starting with a bolus of 250 micrograms 15 minutes before or 2 hours after bile injection. Following blood parameters were determined: lipase, amylase, blood count, minerals, glucose, insulin, gastrin, secretin and CCK. Two controls died within 24 hours, the others were sacrificed after 48 hours. All pancreata were examined morephologically. The controls developed all clinical signs of acute hemorrhagic pancreatitis, whereas all SRIF-treated dogs were in much better general condition. Lipase and amylase increased in all groups. In the controls insulin, gastrin and secretin remained unchanged and CCK rose slightly. SRIF-treatment diminished insulin, CCK and the test meal-induced increase of secretin. At autopsy the pancreata of the controls were nearly entirely apoplectic. The SRIF-treated dogs showed less damage of the pancreas and no severe hemorrhagic necrosis was noted. The beneficial effect of SRIF cannot only be due to an interaction with intestinal hormones. An additional direct protective effect on the exocrine parenchyma is proposed to exist.