Pro-inflammatory effects of hydrogen sulphide on substance P in caerulein-induced acute pancreatitis

Hydrogen sulphide (H(2)S), a novel gasotransmitter, has been recognized to play an important role in inflammation. Cystathionine-gamma-lyase (CSE) is a major H(2)S synthesizing enzyme in the cardiovascular system and DL-propargylglycine (PAG) is an irreversible inhibitor of CSE. Substance P (SP), a product of preprotachykinin-A (PPT-A) gene, is a well-known pro-inflammatory mediator which acts principally through the neurokinin-1 receptor (NK-1R). We have shown an association between H(2)S and SP in pulmonary inflammation as well as a pro-inflammatory role of H(2)S and SP in acute pancreatitis. The present study was aimed to investigate the interplay between pro-inflammatory effects of H(2)S and SP in a murine model of caerulein-induced acute pancreatitis. Acute pancreatitis was induced in mice by 10 hourly intraperitoneal injections of caerulein (50 (g/kg). PAG (100 mg/kg, i.p.) was administered either 1 hr before (prophylactic) or 1 hr after (therapeutic) the first caerulein injection. PAG, given prophylactically as well as therapeutically, significantly reduced plasma H(2)S levels and pancreatic H(2)S synthesizing activities as well as SP concentrations in plasma, pancreas and lung compared with caerulein-induced acute pancreatitis. Furthermore, prophylactic as well as therapeutic administration of PAG significantly reduced PPT-A mRNA expression and NK-1R mRNA expression in both pancreas and lung when compared with caerulein-induced acute pancreatitis. These results suggest that the pro-inflammatory effects of H(2)S may be mediated by SP-NK-1R pathway in acute pancreatitis.     

Effect of CP-96,345 on the expression of adhesion molecules in acute pancreatitis in mice

We investigated the effect of a specific neurokinin-1 receptor (NK1R) antagonist, CP-96,345, on the regulation of the expression of adhesion molecules ICAM-1, VCAM-1, E-selectin, and P-selectin as well as leukocyte recruitment during acute pancreatitis (AP). AP was induced in male Balb/C mice by 10 consecutive hourly intraperitoneal injections of caerulein. In the treatment groups, CP-96,345 was administered at 2.5 mg/kg ip either 30 min before or 1 h after the first caerulein injection. Animals were killed, and the lungs and pancreas were isolated for RNA extraction and RT-PCR or for immunohistochemical staining. mRNA expression of the four adhesion molecules was upregulated in the pancreas during AP. Treatment with CP-96,345 effectively reduced the mRNA expression of P-selectin and E-selectin but not ICAM-1 and VCAM-1. In the lung, ICAM-1, E-selectin, and P-selectin mRNA expression increased during AP. Antagonist treatment suppressed this elevation. Similar expression patterns were seen in the immunohistochemical stainings. Intravital microscopy of the pancreatic microcirculation revealed the effect of CP-96,345 on leukocyte recruitment. The present study provides important information on the relationship between NK1R activation and the regulation of adhesion molecules. Also, this study points to the differential regulation of inflammation in the pancreas and lung with AP.     

Calcitonin gene-related peptide can attenuate or augment pancreatic damage in caerulein-induced pancreatitis in rats.

We have recently shown that treatment with calcitonin gene-related peptide (CGRP) before and during induction of acute pancreatitis exhibits a protective effect against pancreatic damage evoked by overdose of caerulein. Studies in the stomach have shown that administration of CGRP exhibits dual action on gastric mucosa, CGRP administration before induction of gastric lesions, protects gastric mucosa against damage, whereas treatment with this peptide after development of gastric ulcer exacerbates mucosal injury. These observations prompt us to determine the influence of CGRP administrated before and after induction of pancreatitis on development and evolution of pancreatic tissue damage. METHODS: Acute pancreatitis was induced by s.c. infusion of caerulein (10 microg/kg/h) for 5 h. CGRP was administrated (10 microg/kg s.c. per dose) 30 min prior to caerulein infusion and 3 h later during caerulein infusion or at the time 1 h, 4 h and 7 h after the end of caerulein infusion. Rats were sacrificed at the time 0 h, 3 h or 9 h after cessation of caerulein administration. The pancreatic blood flow (PBF), plasma activity of amylase, plasma interleukin-1beta concentration, cell proliferation, biochemical and morphological signs of pancreatitis were examined. RESULTS: Caerulein-induced pancreatitis (CIP) led to 42% decrease in DNA synthesis, 30% inhibition of PBF, as well as, a significant increase in pancreatic weight, plasma amylase activity, plasma interleukin-1beta concentration, and development of the histological signs of pancreatic damage (edema, leukocyte infiltration and vacuolization). Treatment with CGRP prior and during induction of CIP attenuated the pancreatic damage what was manifested by partial reversion of the drop in DNA synthesis (40.9+1.7 v. 34.2+2.0 dpm/microg DNA) and PBF (83+3% v. 70+3%). Increases in pancreatic weight and plasma interleukin-1beta were reduced. Morphology showed improvement of pancreatic integrity. Administration of CGRP after induction of CIP aggravated pancreatic damage what was manifested by additional decrease in PBF and DNA synthesis. Also pancreatic weight as well as histological signs of pancreatic damage were increased. CONCLUSIONS: (1) Administration of CGRP before and during induction of pancreatitis protects pancreas against pancreatic damage. (2) Treatment with CGRP after development of CIP aggravates pancreatic damage.     

Netrin-1 Protects against L-Arginine-Induced Acute Pancreatitis in Mice

Acute pancreatitis (AP) is a common inflammatory disease mediated by damage to acinar cells and subsequent pancreatic inflammation with infiltration of leukocytes. The neuronal guidance protein, netrin-1, has been shown to control leukocyte trafficking and modulate inflammatory responses in several inflammation-based diseases. The present study was aimed toward investigating the effects of netrin-1 in an in vivo model of AP in mice. AP was induced in C57BL/6 mice by administration of two intraperitoneal injections of L-Arginine (4 g/kg). Mice were treated with recombinant mouse netrin-1 at a dose of 1 µg/mouse or vehicle (0.1% BSA) intravenously through the tail vein immediately after the second injection of L-Arginine, and every 24 h thereafter. Mice were sacrificed at several time intervals from 0 to 96 h after the induction of pancreatitis. Blood and tissue samples of pancreas and lung were collected and processed to determine the severity of pancreatitis biochemically and histologically. Immunohistochemical staining demonstrated that netrin-1 was mainly expressed in the islet cells of the normal pancreas and the AP model pancreas, and the pancreatic expression of netrin-1 was down-regulated at both the mRNA and protein levels during the course of AP. Exogenous netrin-1 administration significantly reduced plasma amylase levels, myeloperoxidase activity, pro-inflammatory cytokine production, and pancreas and lung tissue damages. Furthermore, netrin-1 administration did not cause significant inhibition of nuclear factor-kappa B activation in the pancreas of L-Arginine-induced AP. In conclusion, our novel data suggest that netrin-1 is capable of improving damage of pancreas and lung, and exerting anti-inflammatory effects in mice with severe acute pancreatitis. Thus, our results indicate that netrin-1 may constitute a novel target in the management of AP.     

Treatment with antileukinate, a CXCR2 chemokine receptor antagonist, protects mice against acute pancreatitis and associated lung injury

Acute pancreatitis is a common, and as yet incurable, clinical condition, the incidence of which has been increasing over recent years. Chemokines are believed to play a key role in the pathogenesis of acute pancreatitis. We have earlier shown that treatment with a neutralizing antibody against CINC, a CXC chemokine, protects rats against acute pancreatitis-associated lung injury. The hexapeptide antileukinate (Ac-RRWWCR-NH2) is a potent inhibitor of binding of CXC chemokines to the receptors (CXCR2). This study aims to evaluate the effect of treatment with antileukinate on acute pancreatitis and the associated lung injury in mice. Acute pancreatitis was induced in adult male Swiss mice by hourly intra-peritoneal injections of caerulein (50 microg/kg/h) for 10 h. Antileukinate (52.63 mg/kg, s.c.) was administered to mice either 30 min before or 1 h after starting caerulein injections. Severity of acute pancreatitis was determined by measuring plasma amylase, pancreatic water content, pancreatic myeloperoxidase (MPO) activity, pancreatic macrophage inflammatory protein-2 (MIP-2) levels and histological examination of sections of pancreas. A rise in lung MPO activity and histological evidence of lung injury in lung sections was used as criteria for pancreatitis-associated lung injury. Treatment with antileukinate protected mice against acute pancreatitis and associated lung injury, showing thereby that anti-chemokine therapy may be of value in this condition.     

Alteration in inflammatory/apoptotic pathway and histone modifications by nordihydroguaiaretic acid prevents acute pancreatitis in swiss albino mice

Reactive oxygen radicals, pro-inflammatory mediators and cytokines have been implicated in caerulein induced acute pancreatitis. Nordihydroguaiaretic acid (NDGA), a plant lignin, has marked anti-inflammatory properties. The present study aimed to investigate the possible protective effect of NDGA against caerulein induced pancreatitis. Acute pancreatitis was induced by intraperitoneal administration of eight doses of caerulein in male swiss albino mice. NDGA was administered after 9 h of acute pancreatitis induction. Pancreatic damage and the protective effect of NDGA were assessed by oxidative stress parameters and histopathology of pancreas. The mRNA expression of heat shock proteins (DNAJ C15 and HSPD1) was examined by real-time RT-PCR analysis. Expression of HSP 27, NF-κB, TNF-α, p-p38, Bcl-2, p-PP2A, procaspase-3, caspase-3 and histone modifications were examined by western blotting. NDGA attenuated the oxidative stress, led to increased plasma α-amylase and decreased IGF-1 in AP mice. It modulated the mRNA and protein levels of heat shock proteins and reduced the expression of NF-κB, TNF-α and p-p38. It increased the number of TUNEL positive apoptotic cells in the pancreas of AP mice. In addition, NDGA prevented the changes in modifications of histone H3 in acute pancreatitis. To best of our knowledge, this is the first report which suggests that NDGA prevents the progression of acute pancreatitis by involving alteration of histone H3 modifications and modulating the expression of genes involved in inflammatory/apoptotic cascade, which may be responsible for decreased necrosis and increased apoptosis in this model of acute pancreatitis.     

AT1 receptor antagonism ameliorates acute pancreatitis-associated pulmonary injury

Acute pancreatitis (AP) is an inflammatory disease characterized by tissue edema, necrosis and hemorrhage. The mortality rate associated with this disease is particularly high when the inflammation has become systemic. Recently, activation of the pancreatic renin-angiotensin system (RAS) was shown to play a role in AP. The present study investigated whether administering an AT1 receptor antagonist decreases the severity of AP and pancreatitis-induced systemic inflammation, particularly pulmonary injury. Rats with AP-associated lung injury were induced by multiple doses of caerulein, which was demonstrated in the previous studies. Three injections of losartan (200 microg/ kg/h) were given 30 min prior to the first injection of caerulein. The results demonstrated that caerulein injections resulted in significant increases in pancreatic and pulmonary myeloperoxidase (MPO) activities, and losartan treatment attenuates these effects. Lung microvascular permeability was also significantly improved by losartan treatment. Losartan prevented caerulein-induced pancreatic and pulmonary morphological alterations, but not elevations in serum alpha-amylase or pancreas/body weight ratio. These data indicate that losartan treatment can attenuate pancreatic and lung injury. Thus, the implication is that a blockade of AT1 receptors may have a clinical application for the treatment of AP and, perhaps more importantly, subsequent pulmonary complications.     

<Emphasis Type="Italic">S</Emphasis>-Propargyl-cysteine (SPRC) attenuated lipopolysaccharide-induced inflammatory response in H9c2 cells involved in a hydrogen sulfide-dependent mechanism

The present study attempts to investigate the effects of S-propargyl-cysteine (SPRC), a sulfur-containing amino acid, on lipopolysaccharide (LPS)-induced inflammatory response in H9c2 cardiac myocytes. We found that SPRC prevented nuclear factor-κB (NF-κB) activation assessed by NF-κB p65 phosphorylation and IκBα degradation, suppressed LPS-induced extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and intracellular reactive oxygen species (ROS) production. Furthermore, incubation of H9c2 cells with SPRC induced phosphorylation of Akt in a time- and concentration-dependent manner. In addition, SPRC attenuated LPS-induced mRNA and protein expression of tumor necrosis factor-α (TNF-α), and mRNA expression of intercellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synthase (iNOS). The effects of SPRC were abolished by cystathionine γ-lyase [CSE-an enzyme that synthesizes hydrogen sulfide (H₂S)] inhibitor, dl-propargylglycine (PAG), SPRC-induced Akt phosphorylation and TNF-α release was also abolished by the phosphoinositide 3-kinase (PI3K) inhibitor LY294002. Furthermore, SPRC also increased LPS-induced down-regulation expression of CSE and H₂S level in H9c2 cells. PAG abolished SPRC-induced up-regulation of H₂S level. Therefore, we concluded that SPRC produced an anti-inflammatory effect in LPS-stimulated H9c2 cells partly through the CSE/H₂S pathway by impairing IκBα/NF-κB signaling and by activating PI3K/Akt signaling pathway.     

The tripeptide analog feG ameliorates severity of acute pancreatitis in a caerulein mouse model

Acute pancreatitis (AP) is associated with significant morbidity and mortality; however, there is no specific treatment for this disease. A novel salivary tripeptide analog, feG, reduces inflammation in several different animal models of inflammation. The aims of this study were to determine whether feG reduced the severity of AP and modifies the expression of pancreatic ICAM-1 mRNA during AP in a mouse model. AP was induced in mice by hourly (x12) intraperitoneal injections of caerulein. A single dose of feG (100 microg/kg) was coadministered with caerulein either at time 0 h (prophylactic) or 3 h after AP induction (therapeutic). Plasma amylase and pancreatic MPO activities and pancreatic ICAM-1 mRNA expression (by RT-PCR) were measured. Pancreatic sections were histologically assessed for abnormal acinar cells and interstitial space. AP induction produced a sevenfold increase in plasma amylase, a tenfold increase in pancreatic MPO activity, and a threefold increase in interstitial space, and 90% of the acinar cells were abnormal. Prophylactic treatment with feG reduced the AP-induced plasma amylase activity by 45%, pancreatic MPO by 80%, the proportion of abnormal acinar cells by 30%, and interstitial space by 40%. Therapeutic treatment with feG significantly reduced the AP-induced abnormal acinar cells by 10% and the interstitial space by 20%. Pancreatic ICAM-1 mRNA expression was upregulated in AP and was reduced by 50% with prophylactic and therapeutic treatment with feG. We conclude that feG ameliorates experimental AP acting at least in part by modulating ICAM-1 expression in the pancreas.     

Ghrelin attenuates the development of acute pancreatitis in rat.

BACKGROUND: Ghrelin, a circulating growth hormone-releasing peptide isolated from human and rat stomach, stimulates growth hormone secretion, food intake and exhibits gastroprotective properties. Ghrelin is predominantly produced by a population of endocrine cells in the gastric mucosa, but its presence in bowel, pancreas, pituitary and hypothalamus has been reported. In human fetal pancreas, ghrelin is expressed in a prominent endocrine cell population. In adult pancreatic islets the population of these cell is reduced. The aim of present study was to investigate the influence of ghrelin administration on the development of acute pancreatitis. METHODS: Acute pancreatitis was induced in rat by caerulein injection. Ghrelin was administrated twice (30 min prior to the first caerulein or saline injection and 3 h later) at the doses: 2, 10 or 20 nmol/kg. Immediately after cessation of caerulein or saline injections the following parameters were measured: pancreatic blood flow, plasma lipase activity, plasma interleukin-1beta (IL-1beta) and interleukin 10 (IL-10) concentration, pancreatic DNA synthesis, and morphological signs of pancreatitis. RESULTS: Administration of ghrelin without induction of pancreatitis did not affect significantly any parameter tested. Caerulein led to the development of acute edematous pancreatitis. Treatment with ghrelin at the dose 2 nmol/kg, during induction of pancreatitis, was without effect on pancreatic histology or biochemical and functional parameters. Treatment with ghrelin at the dose 10 and 20 nmol/kg attenuated the development of pancreatitis and the effects of both doses were similar. Administration of ghrelin (10 or 20 nmol/kg) reduced inflammatory infiltration of pancreatic tissue and vacuolization of acinar cells. Also, plasma lipase activity and plasma IL-1beta concentration were reduced, and caerulein-induced fall in pancreatic DNA synthesis was reversed. Administration of ghrelin at the dose 10 and 20 nmol/kg was without effect on caerulein-induced pancreatic edema and pancreatitis-related fall in pancreatic blood flow. CONCLUSIONS: (1) Administration of ghrelin attenuates pancreatic damage in caerulein-induced pancreatitis; (2) Protective effect of ghrelin administration seems Background: Ghrelin, a circulating growth hormone-releasing peptide isolated from human and rat stomach, stimulates growth hormone secretion, food intake and exhibits gastroprotective properties. Ghrelin is predominantly produced by a population of endocrine cells in the gastric mucosa, but its presence in bowel, pancreas, pituitary and hypothalamus has been reported. In human fetal pancreas, ghrelin is expressed in a prominent endocrine cell population. In adult pancreatic islets the population of these cell is reduced. The aim of present study was to investigate the influence of ghrelin administration on the development of acute pancreatitis. Methods: Acute pancreatitis was induced in rat by caerulein injection. Ghrelin was administrated twice (30 min prior to the first caerulein or saline injection and 3 h later) at the doses: 2, 10 or 20 nmol/kg. Immediately after cessation of caerulein or saline injections the following parameters were measured: pancreatic blood flow, plasma lipase activity, plasma interleukin-1beta (IL-1beta) and interleukin 10 (IL-10) concentration, pancreatic DNA synthesis, and morphological signs of pancreatitis. Results: Administration of ghrelin without induction of pancreatitis did not affect significantly any parameter tested. Caerulein led to the development of acute edematous pancreatitis. Treatment with ghrelin at the dose 2 nmol/kg, during induction of pancreatitis, was without effect on pancreatic histology or biochemical and functional parameters. Treatment with ghrelin at the dose 10 and 20 nmol/kg attenuated the development of pancreatitis and the effects of both doses were similar. Administration of ghrelin (10 or 20 nmol/kg) reduced inflammatory infiltration of pancreatic tissue and vacuolization of acinar cells. Also, plasma lipase activity and plasma IL-1beta conc; concentration were reduced, and caerulein-induced fall in pancreatic DNA synthesis was reversed. Administration of ghrelin at the dose 10 and 20 nmol/kg was without effect on caerulein-induced pancreatic edema and pancreatitis-related fall in pancreatic blood flow. Conclusions: (1) Administration of ghrelin attenuates pancreatic damage in caerulein-induced pancreatitis; (2) Protective effect of ghrelin administration seems to be related the inhibition in inflammatory process and the reduction in liberation of pro-inflammatory IL-1beta.     

N-acetylcysteine prevents intra-acinar oxygen free radical production in pancreatic duct obstruction-induced acute pancreatitis

Although oxygen free radicals (OFR) are considered to be one of the pathophysiological mechanisms involved in acute pancreatitis (AP), the contribution of acinar cells to their production is not well established. The aim of the present study was to determine the effect of N-acetylcysteine (NAC) in the course of AP induced by pancreatic duct obstruction (PDO) in rats, directly analysing by flow cytometry the quantity of OFR generated in acinar cells. NAC (50 mg/kg) was administered 1 h before and 1 h after PDO. Measurements by flow cytometry of OFR generated in acinar cells were taken at different PDO times over 24 h, using dihydrorhodamine-123 as fluorescent dye. Histological studies of pancreas and measurements of neutrophil infiltration in the pancreas, pancreatic glutathione (GSH), malondialdehyde (MDA) levels, plasma amylase activity and hemoconcentration were carried out in order to assess the severity of AP at different stages. NAC effectively blunted GSH depletion at early AP stages and prevented OFR generation found in acinar cells as a consequence of AP induced by PDO. This attenuation of the redox state impairment reduced cellular oxidative damage, as reflected by less severe pancreatic lesions, normal pancreatic MDA levels, as well as diminished neutrophil infiltration in pancreas. Hyperamylasemia and hemoconcentration following AP induction were ameliorated by NAC administration at early stages, when oxidative stress seems to be critical in the development of pancreatitis. In conclusion, NAC reinforces the antioxidant defences in acinar cells, preventing OFR generation therefore attenuating oxidative damage and subsequently reducing the severity of PDO-induced AP at early stages of the disease.     

The role of neutral endopeptidase in caerulein-induced acute pancreatitis

Substance P (SP) is well known to promote inflammation in acute pancreatitis (AP) by interacting with neurokinin-1 receptor. However, mechanisms that terminate SP-mediated responses are unclear. Neutral endopeptidase (NEP) is a cell-surface enzyme that degrades SP in the extracellular fluid. In this study, we examined the expression and the role of NEP in caerulein-induced AP. Male BALB/c mice (20-25 g) subjected to 3-10 hourly injections of caerulein (50 μg/kg) exhibited reduced NEP activity and protein expression in the pancreas and lungs. Additionally, caerulein (10(-7) M) also downregulated NEP activity and mRNA expression in isolated pancreatic acinar cells. The role of NEP in AP was examined in two opposite ways: inhibition of NEP (phosphoramidon [5 mg/kg] or thiorphan [10 mg/kg]) followed by 6 hourly caerulein injections) or supplementation with exogenous NEP (10 hourly caerulein injections, treatment of recombinant mouse NEP [1 mg/kg] during second caerulein injection). Inhibition of NEP raised SP levels and exacerbated inflammatory conditions in mice. Meanwhile, the severity of AP, determined by histological examination, tissue water content, myeloperoxidase activity, and plasma amylase activity, was markedly better in mice that received exogenous NEP treatment. Our results suggest that NEP is anti-inflammatory in caerulein-induced AP. Acute inhibition of NEP contributes to increased SP levels in caerulein-induced AP, which leads to augmented inflammatory responses in the pancreas and associated lung injury.     

The influence of sensory nerves and CGRP on the pancreatic regeneration after repeated episodes of acute pancreatitis in rats.

Stimulation of capsaicin sensitive nerves or administration of calcitonin gene-related peptide (CGRP) before induction of acute pancreatitis (AP) attenuates pancreatic damage, whereas CGRP administration after development of AP aggravates lesion of pancreatic tissue. The aim of this study was to determine the effect of prolonged activity of sensory nerves or CGRP administration on the pancreatic repair after repeated episodes of AP. Five episodes of acute caerulein-induced pancreatitis (10 microg/kg/h for 5 h s.c.) were performed at weekly intervals in rats receiving either vehicle or capsaicin at the sensory nerve stimulatory dose (0.5 mg/kg, 3 times daily), or CGRP (10 microg/kg, 3 times daily). Two weeks after the last induction of AP morphological signs of pancreatic damage, pancreatic blood flow (PBF), serum and pancreatic amylase activity, fecal chymotrypsin activity, pancreatic weight, pancreatic RNA and DNA content, as well as, serum interleukin-1beta (Il-1beta ) were assessed. Pancreata of animals receiving vehicle alone showed almost full recovery within two weeks after last episode of pancreatitis induction. In capsaicin-treated group of rats, we observed the increase in PBF by 44% and in serum Il-1beta concentration by 91%. The pancreatic amylase activity, fecal activity of chymotrypsin, pancreatic nucleic acids content and DNA synthesis were decreased. In rats treated with CGRP the alterations in PBF, serum Il-1beta concentration, as well as, in pancreatic and fecal activity of enzymes were similar to capsaicin treated group but less pronounced. We conclude that prolonged activity of capsaicin-sensitive sensory nerves and the presence of their main mediator-CGRP during pancreatic regeneration after AP leads to pancreatic functional insufficiency typical for chronic pancreatitis.     

胰腺p-STAT3在急性胰腺炎危重演变中的表达变化

目的：检测信号转导与转录激活因子3（STAT3）在不同程度胰腺炎模型小鼠胰腺组织中表达的变化,探讨其在急性胰腺炎危重演变中的作用。方法：48只健康雄性balb/c小鼠随机分为3组（n=16）：对照组（Con）、轻症急性胰腺炎（MAP）组、重症急性胰腺炎（SAP）组。Con组腹腔注射0.9% NaCl;MAP组腹腔注射雨蛙素;SAP组腹腔注射雨蛙素联合脂多糖;分别于造模后2 h、6 h检测血清淀粉酶的活性;分离胰腺、称重,计算胰腺湿重比;检测肺组织髓过氧化物酶（MPO）活性,评估炎细胞浸润肺组织的程度;HE染色切片,光镜下观察胰腺、肺组织病理学改变; Western blot法检测磷酸化STAT3（p-STAT3）的变化。结果：与Con组比较, MAP组和SAP组在各时间点血清淀粉酶活性和胰腺组织湿重比均升高（P<0.05）;肺组织MPO活性显著升高（P<0.05）,且SAP组肺MPO含量明显高于MAP组（P<0.01）。MAP组和SAP组,在造模后2 h,胰腺和肺均可见不同程度的病理学改变; SAP组在造模后2 h胰腺p-STAT3的表达最高,6 h表达有所减弱;MAP组各时间点仅有微量表达;Con组在各时间点为阴性表达。结论：p-STAT3在轻症急性胰腺炎和重症急性胰腺炎模型小鼠胰腺中的表达差异明显,说明重症急性胰腺炎的重症化与STAT3的活化关系密切;抑制STAT3活化将成为阻止急性胰腺炎重症化的靶点之一。     

Hydrogen sulfide acts as a mediator of inflammation in acute pancreatitis: in vitro studies using isolated mouse pancreatic acinar cells

Hydrogen sulphide (H(2)S) is synthesized from L-cysteine via the action of cystathionine-gamma-lyase (CSE) and cystathionine-beta-synthase (CBS). We have earlier shown that H(2)S acts as a mediator of inflammation. However the mechanism remains unclear. In this study, we investigated the presence of H(2)S and the expression of H(2)S synthesizing enzymes, CSE and CBS, in isolated mouse pancreatic acini. Pancreatic acinar cells from mice were incubated with or without caerulein (10(-7) M for 30 and 60 min). Caerulein increased the levels of H(2)S and CSE mRNA expression while CBS mRNA expression was decreased. In addition, cells pre-treated with DL-propargylglycine (PAG, 3 mM), a CSE inhibitor, reduced the formation of H(2)S in caerulein treated cells, suggesting that CSE may be the main enzyme involved in H(2)S formation in mouse acinar cells. Furthermore, substance P (SP) concentration in the acini and expression of SP gene (preprotachykinin-A, PPT-A) and neurokinin-1 receptor (NK-1R), the primary receptor for SP, are increased in secretagogue caerulein-treated acinar cells. Inhibition of endogenous production of H(2)S by PAG significantly suppressed SP concentration, PPT-A expression and NK1-R expression in the acini. To determine whether H(2)S itself provoked inflammation in acinar cells, the cells were treated with H(2)S donor drug, sodium hydrosulphide (NaHS), (10, 50 and 100 muM), that resulted in a significant increase in SP concentration and expression of PPT-A and NK1-R in acinar cells. These results suggest that the pro-inflammatory effect of H(2)S may be mediated by SP-NK-1R related pathway in mouse pancreatic acinar cells.     

Caerulein-induced acute pancreatitis inhibits protein synthesis through effects on eIF2B and eIF4F

Acute pancreatitis (AP) has been shown in some studies to inhibit total protein synthesis in the pancreas, whereas in other studies, protein synthesis was not affected. Previous in vitro work has shown that high concentrations of cholecystokinin both inhibit protein synthesis and inhibit the activity of the guanine nucleotide exchange factor eukaryotic initiation factor (eIF)2B by increasing the phosphorylation of eIF2alpha. We therefore evaluated in C57BL/6 mice the effects of caerulein-induced AP on pancreatic protein synthesis, eIF2B activity and other protein translation regulatory mechanisms. Repetitive hourly injections of caerulein were administered at 50 microg/kg ip. Pancreatic protein synthesis was reduced 10 min after the initial caerulein administration and was further inhibited after three and five hourly injections. Caerulein inhibited the two major regulatory points of translation initiation: the activity of the guanine nucleotide exchange factor eIF2B (with an increase of eIF2alpha phosphorylation) and the formation of the eIF4F complex due, in part, to degradation of eIF4G. This inhibition was not accounted for by changes in the upstream stimulatory pathway, because caerulein activated Akt as well as phosphorylating the downstream effectors of mTOR, 4E-BP1, and ribosomal protein S6. Caerulein also decreased the phosphorylation of the eukaryotic elongation factor 2, implying that this translation factor was not inhibited in AP. Thus the inhibition of pancreatic protein synthesis in this model of AP most likely results from the inhibition of translation initiation as a result of increased eIF2alpha phosphorylation, reduction of eIF2B activity, and the inhibition of eIF4F complex formation.     

Anti‐inflammatory effects of melatonin in a rat model of caerulein‐induced acute pancreatitis

The purpose of our study was to evaluate the protective effect of melatonin in a rat model of caerulein‐induced acute pancreatitis. For the induction of experimental acute pancreatitis, four subcutaneous injections of caerulein (20 µg kg^–1 body weight) were given to Wistar rats at 2‐h intervals. Melatonin was injected intraperitoneally (25 mg kg^–1 body weight) 30 min before each caerulein injection. After 12 h, rats were sacrificed by decapitation. Blood and pancreas samples were collected and processed for serological and histopathological studies, respectively. Lipase, α‐amylase, corticosterone, total antioxidant power and cytokines interleukin (IL)‐1β, IL‐4 and tumour necrosis factor (TNF)‐α were determined using commercial kits. ANOVA and Tukey tests (P < 0.05) were performed for the statistical analysis of the results. Results showed that the administration of melatonin reduced histological damage induced by caerulein treatment as well as the hyperamylasemia and hyperlipidemia. Corticosterone and antioxidant total power were also reverted to basal activities. Furthermore, melatonin pre‐treatment reduced pro‐inflammatory cytokines IL‐1β and TNF‐α and increased the serum levels of anti‐inflammatory cytokine IL‐4. In conclusion, the findings suggest that the protective effect of melatonin in caerulein‐induced acute pancreatitis is mediated by the anti‐inflammatory ability of this indolamine. Thus, melatonin may have a protective effect against acute pancreatitis. Copyright © 2013 John Wiley & Sons, Ltd.     

The regulatory effect of hydrogen sulfide on hypoxic pulmonary hypertension in rats

Hypoxic pulmonary hypertension (HPH) is an important pathophysiological process. The mechanism of HPH is still not fully understood. Recent studies showed that hydrogen sulfide (H(2)S) could relax vascular smooth muscles and inhibit the proliferation of cultured vascular smooth muscle cells. Our study showed that both the gene expression of cystathionine gamma-lyase (CSE), one of the H(2)S generating enzymes, and the activity of CSE were suppressed in lung tissues during HPH. And the plasma level of H(2)S was decreased during HPH. Exogenous supply of H(2)S could increase the plasma level of H(2)S, enhance CSE activity, and up-regulate CSE gene expression in lung tissue. At the same time, exogenous supply of H(2)S could oppose the elevation of pulmonary arterial pressure and lessen the pulmonary vascular structure remodeling during HPH. The results showed that endogenous H(2)S system was involved and exogenous H(2)S could exert beneficial effect on the pathogenesis of HPH.