Cerulein-induced Pancreatitis In Mice Research Articles

Selective inhibition of soluble TNF using XPro1595 relieves pain and attenuates cerulein-induced pathology in mice

BackgroundSymptoms associated with acute pancreatitis can be debilitating, and treatment remains a challenge. This study aimed to investigate the efficacy of selectively inhibiting the soluble form of TNF (solTNF) using the biologic XPro1595 in a mouse model of acute pancreatitis.MethodsAcute pancreatitis was induced in adult male C57Bl/6J mice by administering cerulein (8 injections of 50 µg/kg I.P., spaced an hour apart), with XPro1595 (10 mg/kg, S.C.) or vehicle being administered approximately 18 h after the last injection. Serum was collected 6 or 18 h after the last cerulein injection, pancreatic tissue was collected 2 and 7 days post-induction, and brain hippocampal tissue was collected at 7 days post-induction. The animal’s pain level was assessed 3, 5 and 7 days post-induction.ResultsThe induction of acute pancreatitis promoted a strong increase in serum amylase levels, which had receded back to baseline levels by the next morning. XPro1595 treatment began after amylase levels had subsided at 18 h, and prevented pancreatic immune cell infiltration, that subsequently prevented tissue disruption and acinar cell death. These improvements in pathology were associated with a significant reduction in mechanical hypersensitivity (neuropathic pain). XPro1595 treatment also prevented an increase in hippocampal astrocyte reactivity, that may be associated with the prevention of neuropathic pain in this mouse model.ConclusionOverall, we observed that selectively inhibiting solTNF using XPro1595 improved the pathophysiological and neurological sequelae of cerulein-induced pancreatitis in mice, which provides support of its use in patients with pancreatitis.

Loss of chymotrypsin-like protease (CTRL) alters intrapancreatic protease activation but not pancreatitis severity in mice

The digestive enzyme chymotrypsin protects the pancreas against pancreatitis by reducing harmful trypsin activity. Genetic deficiency in chymotrypsin increases pancreatitis risk in humans and pancreatitis severity in mice. Pancreatic chymotrypsin is produced in multiple isoforms including chymotrypsin B1, B2, C and chymotrypsin-like protease (CTRL). Here we investigated the role of CTRL in cerulein-induced pancreatitis in mice. Biochemical experiments with recombinant mouse enzymes demonstrated that CTRL cleaved trypsinogens and suppressed trypsin activation. We generated a novel CTRL-deficient strain (Ctrl-KO) using CRISPR-Cas9 genome engineering. Homozygous Ctrl-KO mice expressed no detectable CTRL protein in the pancreas. Remarkably, the total chymotrypsinogen content in Ctrl-KO mice was barely reduced indicating that CTRL is a low-abundance isoform. When given cerulein, Ctrl-KO mice exhibited lower intrapancreatic chymotrypsin activation and a trend for higher trypsin activation, compared with C57BL/6N mice. Despite the altered protease activation, severity of cerulein-induced acute pancreatitis was similar in Ctrl-KO and C57BL/6N mice. We conclude that CTRL is a minor chymotrypsin isoform that plays no significant role in cerulein-induced pancreatitis in mice.

Activating transcription factor 3 promotes loss of the acinar cell phenotype in response to cerulein-induced pancreatitis in mice.

Pancreatitis is a debilitating disease of the exocrine pancreas that, under chronic conditions, is a major susceptibility factor for pancreatic ductal adenocarcinoma (PDAC). Although down-regulation of genes that promote the mature acinar cell fate is required to reduce injury associated with pancreatitis, the factors that promote this repression are unknown. Activating transcription factor 3 (ATF3) is a key mediator of the unfolded protein response, a pathway rapidly activated during pancreatic insult. Using chromatin immunoprecipitation followed by next-generation sequencing, we show that ATF3 is bound to the transcriptional regulatory regions of >30% of differentially expressed genes during the initiation of pancreatitis. Of importance, ATF3-dependent regulation of these genes was observed only upon induction of pancreatitis, with pathways involved in inflammation, acinar cell differentiation, and cell junctions being specifically targeted. Characterizing expression of transcription factors that affect acinar cell differentiation suggested that acinar cells lacking ATF3 maintain a mature cell phenotype during pancreatitis, a finding supported by maintenance of junctional proteins and polarity markers. As a result, Atf3-/- pancreatic tissue displayed increased tissue damage and inflammatory cell infiltration at early time points during injury but, at later time points, showed reduced acinar-to-duct cell metaplasia. Thus our results reveal a critical role for ATF3 as a key regulator of the acinar cell transcriptional response during injury and may provide a link between chronic pancreatitis and PDAC.

Interleukin-22 Ameliorates Cerulein-Induced Pancreatitis in Mice by In-hibiting the Autophagic Pathway (44.15)

Abstract 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 ceru-lein-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-XL, 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.

CCL2-Induced Migration and SOCS3-Mediated Activation of Macrophages Are Involved in Cerulein-Induced Pancreatitis in Mice

Acute pancreatitis is a common inflammatory disease mediated by damage to acinar cells and subsequent pancreatic inflammation with recruitment of leukocytes. We investigated the pathologic roles of innate immune cells, especially macrophages, in cerulein- and L-arginine-induced acute pancreatitis in mice. Acute pancreatitis was induced by sequential peritoneal administration of cerulein to mice. We determined serum concentrations of amylase and lipase, pancreatic pathology, and features of infiltrating mononuclear cells. We performed parabiosis surgery to assess the hemodynamics of pancreatic macrophages. Almost all types of immune cells, except for CD11b(high)CD11c(-) cells, were detected in the pancreas of healthy mice. However, activated CD11b(high)CD11c(-) cells, including Gr-1(low) macrophages and Gr-1(high) cells (granulocytes and myeloid-derived suppressor cells), were detected in damaged pancreas after cerulein administration. CCL2(-/-) mice given cerulein injections developed significantly less severe pancreatitis, with less infiltration of CD11b(high)CD11c(-)Gr-1(low) macrophages, but comparable infiltration of myeloid-derived suppressor cells, compared with cerulein-injected wild-type mice. Parabiosis and bone marrow analyses of these mice revealed that the CD11b(high)CD11c(-)Gr-1(low) macrophages had moved out of the bone marrow. Furthermore, mice with macrophage-specific deletion of suppressor of cytokine signaling 3 given injections of cerulein developed less severe pancreatitis and Gr-1(low) macrophage produced less tumor necrosis factor-α than wild-type mice given cerulein, although the absolute number of CD11b(high)CD11c(-)Gr-1(low) macrophages was comparable between strains. Induction of acute pancreatitis by L-arginine required induction of macrophage migration by CCL2, via the receptor CCR2. Cerulein induction of pancreatitis in mice involves migration of CD11b(high)CD11c(-)Gr-1(low) macrophage from the bone marrow (mediated by CCL2 via CCR2) and suppressor of cytokine signaling 3-dependent activation of macrophage. These findings might lead to new therapeutic strategies for acute pancreatitis.

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-XL, 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.

Fibroblast Growth Factor 21 Reduces the Severity of Cerulein-Induced Pancreatitis in Mice

Fibroblast growth factor 21 (FGF21) acts as a hormonal regulator during fasting and is involved in lipid metabolism. Fgf21 gene expression is regulated by peroxisome proliferator-activated receptor (PPAR)-dependent pathways, which are enhanced during pancreatitis. Therefore, the aim of this study was to investigate FGF21's role in pancreatic injury. Fgf21 expression was quantified during cerulein-induced pancreatitis (CIP) or following mechanical or thapsigargin-induced stress through Northern blot analysis, in situ hybridization, and quantitative reverse transcription polymerase chain reaction. FGF21 protein was quantified by Western blot analysis. Isolated acinar cells or AR42J acinar cells were treated with recombinant FGF21 protein, and extracellular regulated kinase 1/2 activation was examined. The severity of CIP was compared between wild-type mice and mice overexpressing FGF21 (FGF21Tg) or harboring a targeted deletion of Fgf21 (Fgf21(-/-)). Acinar cell Fgf21 expression markedly increased during CIP and following injury in vitro. Purified FGF21 activated the extracellular regulated kinase 1/2 pathway in pancreatic acinar cells. The severity of CIP is inversely correlated to FGF21 expression because FGF21Tg mice exhibited decreased serum amylase and decreased pancreatic stellate cell activation, whereas Fgf21(-/-) mice had increased serum amylase and tissue damage. The expression of Fgf21 was also inversely correlated to expression of Early growth response 1, a proinflammatory and profibrotic transcription factor. These studies suggest a novel function for Fgf21 as an immediate response gene protecting pancreatic acini from overt damage.

T1827 Geranylgeranylacetone Induces Heat Shock Protein 70 in Pancreas and It Ameliorates Cerulein-Induced Pancreatitis in Mice

T1827 Geranylgeranylacetone Induces Heat Shock Protein 70 in Pancreas and It Ameliorates Cerulein-Induced Pancreatitis in Mice

Notch Signaling Is Required for Exocrine Regeneration After Acute Pancreatitis

The mechanisms for tissue regeneration and renewal after acute pancreatitis are not well understood but may involve activation of Notch signaling. To study the effect of Notch signaling ablation during acute experimental pancreatitis, we used a chemical and genetic approach to ablate Notch signaling in cerulein-induced pancreatitis in mice. Acute pancreatitis was induced by cerulein treatment in mice treated with the gamma-secretase inhibitor dibenzazepine or in conditional Notch1 knockout mice. Mice were characterized using immunohistologic, biochemical, and molecular methods. To investigate Notch and beta-catenin interaction, acinar 266-6 cells were analyzed using transfection and biochemical assays. Loss of Notch signaling results in impaired regeneration after acute pancreatitis with fewer mature acinar cells in dibenzazepine-treated and Notch1-deficient mice in the regenerative phase 3 days after induction. beta-catenin expression was increased and prolonged during exocrine regeneration. Crosstalk between Notch and beta-catenin-mediated signaling was identified, with Notch1-IC inhibiting beta-catenin-mediated transcriptional activity. This inhibition was dependent on a functional RAM domain. Inhibition of Notch signaling in vivo leads to impaired regeneration of the exocrine pancreas after acute pancreatitis. Our results suggest an interaction of Notch and Wnt signaling in pancreatic acinar cells, providing evidence for a role of these pathways in the regulation of the maturation process of acinar cells.

Development of cerulein-induced acute pancreatitis is independent of cross-tolerance after heat shock in mice

Introduction: It is logical to believe that, as in many inflammatory conditions, the development of acute pancreatitis may be modified by the heat shock response. Data, however, are conflicting regarding the significance of the heat shock response in acute pancreatitis. The purpose of this study was to examine the role of the inducible heat shock response in the pathogenesis of acute pancreatitis by examining the effects of cerulein hyperstimulation, with or without heat shock preconditioning (i.e., cross-tolerance), in a mouse model lacking heat shock transcription factor 1 (Hsf1), the main regulator of the heat shock response (Xiao et al EMBO J.18:5943, 1999). Methods: Wild-type and homozygous mice (for Hsf1+/+ and Hsf1−/−, respectively) were generated and verified by PCR Pancreatitis was induced in mice by intraperitoneal injection of three hourly doses of cerulein (100 mcg/kg). Control groups received a similar course of carrier injections. Preconditioning was accomplished by heating ansesthetized mice from 37 degrees C to 41 degrees C for 15 minutes (HS preconditioning), 12 hours prior to induction of pancreatitis. Experimental groups with (n=9-10 per group) and without heat shock preconditioning (n=4-5 per group) were studied. Pancreatic markers included serum amylase levels, and blinded histologic assessment of pancreata for necrosis, vacuolization and inflammatory cell infiltration. Western blot for heat shock protein 70 (Hsp70) expression in pancreata was evaluated 6 hours after induction of pancreatitis, a time point corresponding to peak amylase release and histologic injury in this model. Results: In response to cerulein, Hsf1+/+ mice had a 2.4 fold increase in peak amylase vs control (p<0.001). Likewise, Hsf1−/− mice had a 2.8 fold increase in peak amylase vs control (p<0.001). There were no significant differences in peak serum amylase (p= 0.85) and cerulein-induced histologic scoring of tissue injury between experimental groups. Both cerulein and heat shock treatments induced Hsp70 expression in Hsf1+/+ mice, but not in Hsf1−/− mice. However, development of pancreatitis after HS preconditioning was similar in Hsf1+/+ compared with Hsf1−/− (2.4 fold increase vs control and 2.0 fold increase vs control, p<0.001, respectively). Conclusions: Neither cross-tolerance by HS preconditioning nor the induction of Hsp70 affords effective protection against cerulein-induced pancreatitis in mice. Futhermore, our findings demonstrate for the first time that Hsf1, the major stress-inducible regulatory pathway of heat shock protein expression, is dispensable for development of acute pancreatitis. We conclude that other compensatory and redundant mechanisms, independent of the heat shock response, play central roles in the pathogenesis of cerulein-induced acute pancreatitis.

MRNA for pancreatic uncoupling protein 2 increases in two models of acute experimental pancreatitis in rats and mice

Uncoupling-protein 2 (UCP2) is a mitochondrial protein that appears to be involved in cellular oxidant defense and in the regulation of oncotic cell death, both of which are important features of acute pancreatitis. However, UCP2 expression in acute pancreatitis has not been previously reported. In the current experiments, pancreatic gene expression was studied by real-time reverse-transcription/polymerase chain reaction and Northern blots. Two models of acute experimental pancreatitis were investigated: cerulein-induced pancreatitis in mice at two different time points and taurocholate-induced pancreatitis in rats at two degrees of severity. After cerulein administration, acinar injury and leukocyte infiltration was significantly higher at 24 h compared with 12 h after the first injection of cerulein (P<0.05, P<0.005, respectively). UCP2 mRNA was unchanged at 12 h but was nearly 12-fold greater than control levels after 24 h (P<0.001). UCP2 gene expression correlated with acinar injury (r=0.69; P<0.001). By 72 h after taurocholate administration, the severe group had more necrosis than the mild group (P<0.005). Pancreatic UCP2 mRNA was increased fourfold in the severe group compared with controls (P<0.01). UCP2 expression correlated with parenchymal necrosis (r=0.61; P<0.01). Thus, pancreatic UCP2 mRNA increased in two models of acute pancreatitis. The increase in UCP2 gene expression was correlated with the severity of the disease. Up-regulation of UCP2 in the pancreas may be a protective response to oxidative stress, but this increase may also have a negative influence on cellular energy metabolism. Therefore, acinar UCP2 may be an important modifier of the severity of acute pancreatitis.

Progressive disruption of acinar cell calcium signaling is an early feature of cerulein-induced pancreatitis in mice

BACKGROUND & AIMS: Disruption of pancreatic exocrine secretion is an important feature of acute pancreatitis. Because cytosolic calcium is a key intracellular messenger controlling pancreatic secretion, this study examined patterns of calcium signaling during the early stages of cerulein-induced pancreatitis. METHODS: Mice were administered hourly intraperitoneal injections of cerulein (50 micrograms/kg), and paired controls were administered saline. Acini were isolated by collagenase from pancreatic tissue harvested after injections 1, 3, 5, and 7 and were loaded with Fura-2. Individual cellular calcium responses to acetylcholine and cholecystokinin were studied using digital imaging. RESULTS: The proportion of cells maintaining a normal oscillatory calcium response to physiological secretagogue stimulation diminished progressively after increasing cerulein injections. Also, the normal polarized spatial pattern of calcium Increase within individual acinar cells was progressively lost. A sustained response to high-dose stimulation was maintained but with diminishing amplitude. The characteristic calcium response to the Ca(2+)-adenosine triphosphatase inhibitor thapsigargin was maintained, implying that calcium reuptake and extrusion were not impaired. CONCLUSIONS: Progressive disruption of physiological patterns of pancreatic acinar cell calcium signaling, notably in the secretory pole of the cell, is an early feature of pancreatitis induced by cerulein hyperstimulation. These changes may be important in contributing to the disruption of exocrine secretion in acute pancreatitis. (Gastroenterology 1996 Aug;111(2):481-91)

The role of nitric oxide in mouse cerulein-induced pancreatitis with and without lipopolysaccharide pretreatment.

Nitric oxide (NO) has been shown to play a significant role in inflammation. To clarify the role of NO in acute pancreatitis, we investigated the serum concentrations of NO chi (NO2- plus NO3-) and tumor necrosis factor-alpha (TNF-alpha) and the grade of pancreatitis in cerulein-induced pancreatitis in mice pretreated with lipopolysaccharide (LPS) or not. LPS pretreatment aggravated the cerulein pancreatitis in association with a transient increase in serum TNF-alpha, which was followed by a gradual elevation of serum NO chi. This elevation of serum NO chi concentration was inhibited by the NO synthase inhibitor NG-nitro-L-arginine (L-NNA). In addition, the activity of NADPH-diaphorase (NADPH-d), a marker for NO synthase, appeared in the peritoneal macrophages of LPS-pretreated mice after the induction of pancreatitis. No elevation of serum NO chi or appearance of NADPH-d activity in peritoneal cells was found in mice without LPS pretreatment. Administration of L-NNA enhanced the elevation of pancreatitis-induced serum amylase in mice untreated with LPS, while L-NNA inhibited the elevation in LPS-pretreated mice. The effects of L-NNA were reversed by the administration of L-arginine but were not affected by D-arginine. These results suggested that (a) inflammatory cells may not be fully activated to produce excessive NO in uncomplicated edematous pancreatitis, and (b) edematous pancreatitis may be aggravated by excessively produced NO if bacterial infection is complicated and inflammatory cells are activated to express inducible NO synthase.