Experimental Chronic Pancreatitis Research Articles

Nanoceria Ameliorates Fibrosis, Inflammation, and Cellular Stress in Experimental Chronic Pancreatitis

Chronic pancreatitis (CP) is an inflammatory, irreversible disorder of the pancreas which leads to organ atrophy and poses high risk for the development of pancreatic cancer. Given the lack of clinically approved therapy, we explored the pharmacological potential of the nanoparticles of cerium oxide (nanoceria, NC) against animal models of CP. Nanoceria ameliorated the features of CP as evident from biochemical parameters. It inhibited the inflammatory cytokines and chemokines by abrogation of macrophage signaling. Further, NC attenuated the fibrogenesis by inhibition of TGF-β signaling, endoplasmic reticulum stress, and epithelial-to-mesenchymal transition. Our findings reveal the anti-CP potential of the novel redox regenerative nanoceria against two models of CP.

Intraductal pressure in experimental models of acute and chronic pancreatitis in mice

Background/ObjectivesPancreatic intraductal pressure is related to the development of pancreatitis, including post-ERCP (endoscopic retrograde cholangiopancreatography) pancreatitis. In this study, we investigate pancreatic intraductal pressure in various mouse models of acute and chronic pancreatitis. MethodsPost-ERCP pancreatitis was induced by retrograde infusion of normal saline or radiocontrast at the constant rate of 10 or 20 μL/min. Obstructive pancreatitis was induced by ligation of the pancreatic duct followed by a single injection of caerulein and the changes of intraductal pressure were recorded in day 3 for obstructive acute pancreatitis and day 14 for obstructive chronic pancreatitis. Non-obstructive pancreatitis was induced by repetitive intraperitoneal injections of caerulein. The changes of intraductal pressure were recorded right after the last caerulein injection for non-obstructive acute pancreatitis and after the completion of 4-week caerulein injections for non-obstructive chronic pancreatitis. ResultsElevated pancreatic intraductal pressure was observed in both normal saline and radiocontrast infusion groups and was furtherly indicated that was positively correlated with the viscosity of solution but not genders. In the models of obstructive pancreatitis, a rise in intraductal pressure was observed in both acute and chronic pancreatitis; whereas in the models of non-obstructive pancreatitis, a rise in intraductal pressure was only observed in chronic, but not acute pancreatitis. ConclusionsDuring ERCP, the elevations in pancreatic intraductal pressure are induced by increasing rate or viscous solution of infusion. During different forms of experimental acute and chronic pancreatitis, obstructive or non-obstructive etiologies of pancreatitis also induces the elevations in pancreatic intraductal pressure.

Aspirin Ameliorates Pancreatic Inflammation and Fibrosis by Inhibiting COX-2 Expression in Experimental Chronic Pancreatitis.

AimChronic pancreatitis (CP) is a complex and intractable disease mainly manifested as chronic inflammation and fibrosis. Aspirin(acetylsalicylic acid, ASA) has been reported to be used in the treatment of acute pancreatitis (AP), but its effectiveness on CP is unclear. This study aimed to investigate the therapeutic effects of ASA in CP mice.MethodsA murine model of CP was induced by intraperitoneal injection with 20% L-arginine. After one week of L-arginine administration, mice in the ASA treatment group were administered aspirin (100mg/kg/d) by intragastric gavage. At two, four, and six weeks after the first injection of L-arginine, mice were euthanized and the pancreas was collected for histological and molecular analysis. A second model of CP (caeruelin-induced) was used as a validation experiment to test the effect of ASA.ResultsL-arginine-induced CP resulted in over-expression of the inflammatory enzyme cyclooxygenase (COX)-2. COX-2 expression decreased after ASA treatment. Pancreatic-injury inflammatory response (measured by changes in amylase, CK-19, F4/80, CD3, MCP-1, IL-6) and fibrosis degree (measured by expression of COL1A1, MMP-1 and TIMP-1) was reduce in ASA -treated mice model. The therapeutic effect of ASA was also observed in caeruelin-induced CP.ConclusionASA has an ameliorating effect in murine models of CP through inhibition of pancreatic inflammation and fibrosis, which may be a promising option for clinical treatment.

Trimetazidine has Promising Preventive Effects on Experimental Chronic Pancreatitis Rat Model.

It was aimed to evaluate the preventive efficacy of trimetazidine in an experimental chronic pancreatitis rat model. Chronic pancreatitis model was accomplished with caerulein and alcohol administration. In the study, 40 female Sprague Dawley rats were randomized into 5 groups containing 8 animals in each. Group 1 (chronic pancreatitis); group 2 (chronic pancreati- tis+low-dose trimetazidine group); group 3 (chronic pancreatitis+high-dose trimetazidine group); group 4 (placebo group (chronic pancreatitis + saline)); group 5 (sham group). 24 hours after the last injection, all animals were sacrificed. Tumor necrosis factor-alpha, transforming growth factor-β, malondialdehyde, and glutathione peroxidase levels were tested in blood samples. Histopathologic exam- inations were conducted by a senior pathologist who was unaware of the group allocations. Results of biochemical parameters of the trimetazidine groups (groups 2 and 3) were significantly favorable compared with the chronic pancreatitis group (group 1) (P < .05). The difference between the low-dose- and the high-dose trimetazidine group (group 3) was significant in terms of blood tests (P < .05). The difference between the low-dose trimetazidine group and the chronic pancreatitis group was not significant in terms of histopathologic scores (P > .05); however, the difference was significant between the high-dose trimetazidine group and the chronic pancreatitis group (P < .05). To the best of our knowledge, this current research is the first study that evaluates trimetazidine's efficacy in the chronic pancreatitis rat model. Trimetazidine has affirmative preventive properties in the chronic pancreatitis course.

Eosinophils have a critical role in promoting pancreatic malignancy in experimental chronic pancreatitis

Eosinophils have a critical role in promoting pancreatic malignancy in experimental chronic pancreatitis

Targeting of Smad7 in Mesenchymal Cells Does Not Exacerbate Fibrosis During Experimental Chronic Pancreatitis.

Transforming growth factor-β (TGF-β)-mediated accumulation of extracellular matrix proteins such as collagen I is a common feature of fibrosis. Pancreatic stellate cells play an integral role in the pathogenesis of pancreatitis, and their profibrotic ability is mainly mediated by TGF-β signaling. To specifically address the role of fibrogenic cells in experimental pancreatic fibrosis, we deleted Smad7, the main feedback inhibitor of TGF-β signaling in this cell type in mice. A mouse strain harboring a conditional knockout allele of Smad7 (Smad7fl/fl) with the tamoxifen-inducible inducible Col1a2-CreERT allele was generated and compared with wild-type mice challenged with the cerulein-based model of chronic pancreatitis. Pancreatic stellate cells lacking Smad7 had significantly increased collagen I and fibronectin production and showed a higher activation level in vitro. Surprisingly, the fibrotic index in the pancreata of treated conditional knockout mice was only slightly increased, without statistical significance. Except for fibronectin, the expression of different extracellular matrix proteins and the numbers of fibroblasts and inflammatory cells were similar between Smad7-mutant and control mice. There was no clear evidence that the lack of Smad7 in pancreatic stellate cells plays a major role in experimental pancreatitis, at least in the mouse model investigated here.

Melatonin has favorable preventive effects on experimental chronic pancreatitis rat model.

Background/aim Currently, there is not any specific treatment for chronic pancreatitis (CP). It was aimed to investigate the effects of melatonin administration on endoplasmic reticulum (ER) stress, oxidative stress, fibrosis, biochemical and histopathological parameters, and Abcc2,Abcc5, and Abcg2 gene levels in an experimental rat CP model.Materials and methods Forty rats were randomized into five groups: Sham, CP, CP+25 mg/kg melatonin, CP+50 mg/kg melatonin, and CP+placebo. In all rats, except the sham group, a model of chronic pancreatitis was accomplished with intraperitoneal caerulein administration. In treatment groups, melatonin was used as a therapeutic agent. Serum TGF-β, TNF-α, MDA and GPx levels were studied. Pancreatic tissues were evaluated histopathologically. The expression levels of αSma,IR1α,Perk,Abcc2,Abcc5, and Abcg2 genes were measured with the qRT-PCR.Results Biochemical results of the melatonin groups exhibited favorable changes compared to the CP and placebo groups. α Sma,IR1α,Perk expression levels were significantly lower in the melatonin groups. The expression levels of Abcc2, Abcc5, and Abcg2 were significantly higher in the CP group compared to the sham group, and these gene levels were significantly lower in the melatonin groups compared to the CP group (p < 0.01, p < 0.05, p < 0.05, respectively).Conclusion In light of these favorable positive results, melatonin may be a useful preventive agent in the course of CP.

Loss of miR-29a/b1 promotes inflammation and fibrosis in acute pancreatitis.

MicroRNA-29 (miR-29) is a critical regulator of fibroinflammatory processes in human diseases. In this study, we found a decrease in miR-29a in experimental and human chronic pancreatitis, leading us to investigate the regulatory role of the miR-29a/b1 cluster in acute pancreatitis (AP) utilizing a conditional miR-29a/b1–KO mouse model. miR-29a/b1-sufficient (WT) and -deficient (KO) mice were administered supramaximal caerulein to induce AP and characterized at different time points, utilizing an array of IHC and biochemical analyses for AP parameters. In caerulein-induced WT mice, miR-29a remained dramatically downregulated at injury. Despite high-inflammatory milieu, fibrosis, and parenchymal disarray in the WT mice during early AP, the pancreata fully restored during recovery. miR-29a/b1–KO mice showed significantly greater inflammation, lymphocyte infiltration, macrophage polarization, and ECM deposition, continuing until late recovery with persistent parenchymal disorganization. The increased pancreatic fibrosis was accompanied by enhanced TGFβ1 coupled with persistent αSMA+ PSC activation. Additionally, these mice exhibited higher circulating IL-6 and inflammation in lung parenchyma. Together, this collection of studies indicates that depletion of miR-29a/b1 cluster impacts the fibroinflammatory mechanisms of AP, resulting in (a) aggravated pathogenesis and (b) delayed recovery from the disease, suggesting a protective role of the molecule against AP.

Differential expressions of miR-223, miR-424, miR-145, miR-200c, miR-139 in experimental rat chronic pancreatitis model and their relationship between oxidative stress, endoplasmic reticulum stress, and apoptosis.

Objective(s):This study aimed to research the roles of miR-139, miR-221, miR-200c, miR-145, miR-223, miR-424, and miR-377 in endoplasmic reticulum stress (ERS), oxidative stress (OS), fibrosis, and apoptosis processes in chronic pancreatitis (CP) rat model. Materials and Methods:Fourteen rats were randomized into 2 groups (Group 1, sham group (n=7) and Group 2, CP group (n=7)). TGF-beta and malondialdehyde concentrations were measured in rat blood samples. qRT-PCR was used to investigate the expression levels of 7 miRNAs in the pancreas tissues. The correlations of mRNA undergoing significant changes with inflammation (TNF-α, IL-6), ERS (Ire1-α, Perk), apoptosis (Caspase 3, Bcl-2), OS (Cat, Gpx1), and fibrosis (α-Sma) were investigated.Results:The biochemical results and histopathological scores in Group 1 were statistically significantly high compared with Group 2 (P<0.5). Expression levels of seven miRNAs (miR-200c, miR-145, miR-223, miR-424) were significantly higher, while miR-139 was significantly lower in CP. In our study, we found that miR-200c, miR-145, and miR-139 may contribute to CP progression and cellular processes based on the correlation between ERS, OS, apoptosis, and inflammation with miRNA expression levels. Conclusion:miR-200c, miR-145, miR-139, miR-223, and miR-424 play roles in the CP model. They may be used as candidate biomarkers for the CP process.

Loss of muscle mass and strength in experimental chronic pancreatitis

Loss of muscle mass and strength in experimental chronic pancreatitis

Inhibition of discoidin domain receptors by imatinib prevented pancreatic fibrosis demonstrated in experimental chronic pancreatitis model

Discoidin domain receptors (DDR1 and DDR2) are the collagen receptors of the family tyrosine kinases, which play significant role in the diseases like inflammation, fibrosis and cancer. Chronic pancreatitis (CP) is a fibro-inflammatory disease in which recurrent pancreatic inflammation leads to pancreatic fibrosis. In the present study, we have investigated the role of DDR1 and DDR2 in CP. The induced expression of DDR1 and DDR2 was observed in primary pancreatic stellate cells (PSCs) and cerulein-induced CP. Subsequently, the protective effects of DDR1/DDR2 inhibitor, imatinib (IMT) were investigated. Pharmacological intervention with IMT effectively downregulated DDR1 and DDR2 expression. Further, IMT treatment reduced pancreatic injury, inflammation, extracellular matrix deposition and PSCs activation along with inhibition of TGF-β1/Smad signaling pathway. Taken together, these results suggest that inhibition of DDR1 and DDR2 controls pancreatic inflammation and fibrosis, which could represent an attractive and promising therapeutic strategy for the treatment of CP.

Pentoxifylline has favorable preventive effects on experimental chronic pancreatitis model

Background: To investigate the protective efficacy of pentoxifylline through biochemical parameters and histopathological scores in a caerulein- and alcohol-induced experimental model of chronic pancreatitis in rats.Methods: A model of chronic pancreatitis with caerulein and alcohol was created in female rats of the genus Sprague Dawley. Pentoxifylline was administered in doses of 25 mg/kg (low dose) and 50 mg/kg (high dose) as a protective agent. Each group contained 8 animals. The groups were: group 1 (control group); caerulein + alcohol, group 2 (low-dose pentoxifylline group); caerulein + alcohol + pentoxifylline 25 mg/kg, group 3 (high-dose pentoxifylline group); caerulein + alcohol + pentoxifylline 50 mg/kg, group 4 (placebo); caerulein + alcohol + saline, group 5 (sham group); only saline injection.Rats were sacrificed 12 h after the last injection, and TNF-α, TGF-β, MDA, and GPx concentrations were measured in blood samples. The histopathologic examination was conducted by a pathologist who was unaware of the groups.Results: The biochemical results of the treatment groups (group 2 and group 3) were statistically significantly lower compared with the control group (group 1) (p < .05). The difference between the low-dose treatment group (group 2) and high-dose treatment group (group 3) was significant in terms of biochemical parameters (p < .05). The difference between group 2 and the control group was not significant in terms of histopathologic scores (p > .05), whereas the difference between the group 3 and the control group was statistically significant (p < .05).Conclusions: As a result, pentoxifylline, which has anti-inflammatory and antioxidant properties, was shown to have protective efficacy in an experimentally generated model of chronic pancreatitis.

Natural single-nucleotide deletion in chymotrypsinogen C gene increases severity of secretagogue-induced pancreatitis in C57BL/6 mice.

Genetic susceptibility to chronic pancreatitis in humans is frequently associated with mutations that increase activation of the digestive protease trypsin. Intrapancreatic trypsin activation is an early event in experimental acute pancreatitis in rodents, suggesting that trypsin is a key driver of pathology. In contrast to trypsin, the pancreatic protease chymotrypsin serves a protective function by mitigating trypsin activation through degradation. In humans, loss-of-function mutations in chymotrypsin C (CTRC) are common risk factors for chronic pancreatitis; however, the pathogenic effect of CTRC deficiency has not been corroborated in animal models yet. Here we report that C57BL/6 mice that are widely used for genetic manipulations do not express functional CTRC due to a single-nucleotide deletion in exon 2 of the Ctrc gene. We restored a functional Ctrc locus in C57BL/6N mice and demonstrated that in the novel Ctrc+ strain the severity of cerulein-induced experimental acute and chronic pancreatitis was significantly ameliorated. Improved disease parameters were associated with reduced intrapancreatic trypsin activation suggesting a causal link between CTRC-mediated trypsinogen degradation and protection against pancreatitis. Taken together with prior human genetic and biochemical studies, the observations provide conclusive evidence for the protective role of CTRC against pancreatitis.

Smad7 is required for normal macrophage function in experimental chronic pancreatitis

Smad7 is required for normal macrophage function in experimental chronic pancreatitis

Induction of Pancreatic Inflammation Accelerates Pancreatic Tumorigenesis in Mice.

Pancreatitis is a major risk factor for the development of pancreatic cancer. In genetically engineered mouse models, induction of pancreatic inflammation dramatically accelerates oncogenic KRas-induced fibrosis, precancerous PanIN formation, and tumorigenesis. Here we describe simple methods of secretagogue-induced experimental acute and chronic pancreatitis, the most commonly used pancreatitis models, and their applications in pancreatic cancer research. Additionally, the preparation of primary pancreatic acinar cells is introduced. Primary acinar cells can be used to study the early events of pancreatic inflammation and pancreatic acinar-to-ductal (ADM) metaplasia.

Inhibition of Class I Histone Deacetylases Abrogates Tumor Growth Factor β Expression and Development of Fibrosis during Chronic Pancreatitis.

Pancreatic fibrosis is the hallmark of chronic pancreatitis, a highly debilitating disease for which there is currently no cure. The key event at the basis of pancreatic fibrosis is the deposition of extracellular matrix proteins by activated pancreatic stellate cells (PSCs). Transforming growth factor β (TGFβ) is a potent profibrotic factor in the pancreas as it promotes the activation of PSC; thus, pharmacologic interventions that effectively reduce TGFβ expression harbor considerable therapeutic potential in the treatment of chronic pancreatitis. In this study, we investigated whether TGFβ expression is reduced by pharmacologic inhibition of the epigenetic modifiers histone deacetylases (HDACs). To address this aim, chronic pancreatitis was induced in C57BL/6 mice with serial injections of cerulein, and the selective class 1 HDAC inhibitor MS-275 was administered in vivo in a preventive and therapeutic manner. Both MS-275 regimens potently reduced deposition of extracellular matrix and development of fibrosis in the pancreas after 4 weeks of chronic pancreatitis. Reduced pancreatic fibrosis was concomitant with lower expression of pancreatic TGFβ and consequent reduced PSC activation. In search of the cell types targeted by the inhibitor, we found that MS-275 treatment abrogated the expression of TGFβ in acinar cells stimulated by cerulein treatment. Our study demonstrates that MS-275 is an effective antifibrotic agent in the context of experimental chronic pancreatitis and thus may constitute a valid therapeutic intervention for this severe disease.

Luteolin Ameliorates Experimental Chronic Pancreatitis Induced by Trinitrobenzenesulfonic Acid in Rats.

The purpose of this study is to assess the effect and possible mechanism of luteolin on chronic pancreatitis (CP). Trinitrobenzenesulfonic acid-induced CP was used as CP models in vivo. After the intervention of luteolin for 28 days, chronic pancreatic injury was assessed by serum hydroxyproline and pancreatic histology. α-Smooth muscle actin (α-SMA) expression was performed to detect the activation of pancreatic stellate cells (PSCs). Pancreatic stellate cells were also isolated and cultured in vitro, and the effect of luteolin on PSCs was evaluated. Transforming growth factor β (TGF-β1) signaling and its regulated mRNA expression was tested by Western blot and quantitative real-time polymerase chain reaction, respectively. The protective role of luteolin on CP was confirmed by increased pancreas/body weight ratio, decreased pancreas hydroxyproline level, and reduced fibrosis. α-SMA expressions in PSCs were significantly decreased both in vitro and in vivo after the management of luteolin. Pancreas TGF-β1 expression was significantly decreased by luteolin. Luteolin inhibited the proliferation and activation of PSCs in a dose-dependent manner. Luteolin played a protective role in CP in many aspects, partly by regulating release of inflammatory cytokines through TGF-β1 signaling pathway.

Enteric motor dysfunctions in experimental chronic pancreatitis: Alterations of myenteric neurons regulating colonic motility in rats.

The mechanism underlying gastrointestinal (GI) dysmotility associated with chronic pancreatitis (CP) has not been fully elucidated, and enteric nervous system (ENS) has an important regulatory role in gastrointestinal motor function. The aim of this study is to investigate the effect of ENS in the colonic hypomotility induced by trinitrobenzene sulfonic acid (TNBS) infusion which mimics CP. Male Sprague-Dawley rats were submitted to CP which was induced by pancreatic infusion of 2% TNBS, or sham group with treatment of equal saline. Three weeks after induction of CP, we pathologically examined the inflammation of pancreas and counted the number of withdrawal events stimulated by Von Frey filaments to evaluate hyperalgesia. The gastrointestinal transit rate was measured using Carbon inkl driving test, and the contraction activities of colonic muscle strip were studied in an organ bath system. The expression of choline acetyltransferase (ChAT) and nitric oxide synthase (NOS) in colonic myenteric plexus (MP) of ENS were investigated by Western blotting and double immunofluorescence staining. In TNBS-treated group, rats had the signs of chronic pancreatitis 3weeks after intraductal infusion and had increased sensitivity to mechanical stimulation of the abdomen. For rats with CP, the gastrointestinal transit rate was reduced; in addition, the contractile activities of longitudinal muscle (LM) and circular muscle (CM) strips of distal colon in TNBS group were lower than those in sham group. Immunofluorescence demonstrated that the percentage of ChAT-immunoreactive (IR) neurons in the MP was decreased, but the proportion of NOS-IR neurons in the MP was increased when compared with sham-operated group. Western blotting proved that TNBS infusion down-regulated ChAT but up-regulated NOS expression in the colon MP. Decreased ChAT-IR neurons and increased NOS-IR in the MP of colon ENS may contribute to the pathogenesis of colonic dysmotility in CP.

Resveratrol Ameliorates the Severity of Fibrogenesis in Mice with Experimental Chronic Pancreatitis.

Resveratrol is generally considered beneficial to health-span and longevity since this dietary stilbenoid has been scrutinized for its activating property on the "rescue gene" sirtuin-1 that promotes cellular survival under stress. In addition to its antiaging property, our previous in vitro studies revealed that resveratrol notably inhibits the production of extracellular matrix (ECM) proteins in pancreatic stellate cells (PSCs), the classic effector cells against pancreatic injury. We aim to extrapolate resveratrol intervention to the management of fibrogenesis in mice with chronic pancreatitis. C57/BL6 mice are given repetitive injections of cerulein (50 μgkg-1 h-1 ) for 6 weeks for the induction of chronic pancreatitis. We demonstrate that the oral administration of resveratrol (20 mgkg-1 d-1 ) effectively attenuated PSC activation, ECM deposition, fibrogenesis, and acinar atrophy in the pancreatitic parenchyma of cerulein-induced mice, as the damage index score was improved by 45.5%. The enhanced cell survival and preserved acinar integrity by resveratrol plausibly involves a perpetuated nuclear accumulation of Mist1 and a negative modulation of the Akt and p38 MAPK pathways. We suggest that resveratrol is potentially a nutraceutical for the mitigations of pancreatic fibrosis in chronic pancreatitis for which no effective therapeutic measure is currently available.

Adipose Stem Cell Therapy Mitigates Chronic Pancreatitis via Differentiation into Acinar-like Cells in Mice

The objective of this study was to assess the capacity of adipose-derived mesenchymal stem cells (ASCs) to mitigate disease progression in an experimental chronic pancreatitis mouse model. Chronic pancreatitis (CP) was induced in C57BL/6 mice by repeated ethanol and cerulein injection, and mice were then infused with 4× 105 or 1× 106 GFP+ ASCs. Pancreas morphology, fibrosis, inflammation, and presence of GFP+ ASCs in pancreases were assessed 2weeks after treatment. We found that ASC infusion attenuated pancreatic damage, preserved pancreas morphology, and reduced pancreatic fibrosis and cell death. GFP+ ASCs migrated to pancreas and differentiated into amylase+ cells. In further confirmation of the plasticity of ASCs, ASCs co-cultured with acinar cells in aTranswell system differentiated into amylase+ cells with increased expression of acinar cell-specific genes including amylase and chymoB1. Furthermore, culture of acinar or pancreatic stellate cell lines in ASC-conditioned medium attenuated ethanol and cerulein-induced pro-inflammatory cytokine production invitro. Our data show that a single intravenous injection of ASCs ameliorated CP progression, likely by directly differentiating into acinar-like cells and by suppressing inflammation, fibrosis, and pancreatic tissue damage. These results suggest that ASC cell therapy has the potential to be a valuable treatment for patients with pancreatitis.