Study on free radicals and pancreatic fibrosis--pancreatic fibrosis induced by repeated injections of superoxide dismutase inhibitor

Yttrium Oxide Nanoparticles Attenuate L-Arginine Induced Chronic Pancreatitis

In this work, we tested the efficacy of yttrium oxide nanoparticles (NY), a promising antioxidant and anti-inflammatory agent, in L-arginine (L-Arg) induced chronic pancreatitis (CP) model. The nanoparticles were characterized using multiple techniques including transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (pXRD), and Energy dispersive X-ray analysis (EDX). The rats were divided into three groups: normal control, L-Arg control, L-Arg + NY (1 mg/kg). We probed the mechanistic effects of the NY by ELISA, multiplex analysis of TGF-β pathway and inflammatory cytokines and immunoblotting. NY treatment significantly reduced pancreatic oxidative-nitrosative stress. In addition, NY intervention also reduced inflammatory cytokines and chemokines resulting in the inhibition of fibrosis signaling. Further, NY treatment suppressed the TGF-β signaling and epithelial-mesenchymal transition (EMT). We conclude that NY shows potential antioxidant, anti-inflammatory, and anti-fibrotic effects against CP and associated fibrosis.

A Macrophage Membrane-Polymer Hybrid Biomimetic Nanoplatform for Therapeutic Delivery of Somatostatin Peptide to Chronic Pancreatitis

The clinical translation of therapeutic peptides is generally challenged by multiple issues involving absorption, distribution, metabolism and excretion. In this study, a macrophage membrane-coated poly(lactic-co-glycolic acid) (PLGA) nanodelivery system was developed to enhance the bioavailability of the somatostatin (SST) peptide, which faces the hurdles of short half-life and potential side effects in the treatment of chronic pancreatitis. Using a facile nanoprecipitation strategy, SST was loaded in the nanoparticles with an encapsulation efficiency (EE) and a loading efficiency (LE) of 73.68 ± 3.56% and 1.47 ± 0.07%, respectively. The final formulation of SST-loaded nanoparticles with the camouflage of macrophage membrane (MP-SST) showed a mean diameter of 151 ± 4 nm and an average zeta potential of −29.6 ± 0.3 mV, which were stable long term during storage. With an above 90% cell viability, a hemolysis level of about 2% (<5%) and a preference for being ingested by activated endothelial cells compared to macrophages, the membrane−polymer hybrid nanoparticle showed biocompatibility and targeting capability in vitro. After being intravenously administered to mice with chronic pancreatitis, the MP-SST increased the content of SST in the serum (123.6 ± 13.6 pg/mL) and pancreas (1144.9 ± 206.2 pg/g) compared to the treatment of (Dulbecco’s phosphate-buffered saline) DPBS (61.7 ± 6.0 pg/mL in serum and 740.2 ± 172.4 pg/g in the pancreas). The recovery of SST by MP-SST downregulated the expressions of chronic pancreatitis-related factors and alleviated the histologic severity of the pancreas to the greatest extent compared to other treatment groups. This augmentation of SST therapeutic effects demonstrated the superiority of integrating the synthetic polymer with biological membranes in the design of nanoplatforms for advanced and smart peptide delivery. Other peptides like SST can also be delivered via the membrane−polymer hybrid nanosystem for the treatment of diseases, broadening and promoting the potential clinical applications of peptides as therapeutics.

Effects of rosuvastatin on serum glucose and insulin in hyperuricemic rats

Background

Hyperuricemia is a state in which the serum levels of uric acid (UA) are elevated. This study was to determine the roles of rosuvastatin in fasting blood glucose (FGB) and insulin levels in hyperuricemic rats.

Methods

Thirty-six Sprague-Dawley (SD) rats were randomized divided into the control, model and rosuvastatin groups: the control was given no intervention, the model group was established by administrating yeast extract powder and oxonic acid potassium salt, and the rosuvastatin group was given intravenous administration of rosuvastatin for 28 days in hyperuricemic rats. Serum uric acid (SUA), fasting blood glucose (FBG), fasting blood insulin (FBI), glutamic acid decarboxylase antibody (GADA), oral glucose tolerance test (OGTT) levels, and the ultrastructure of pancreatic β-cells were measured. Also, homeostasis model assessment of insulin resistance (HOMA-IR) scores was computed in three groups.

Results

Compared to the model group, SUA were decreased, while the FBG, GADA, OGTT and HOMA-IR at week 4 were significantly increased in rosuvastatin group. However, FBI was not significantly changed between three groups. It was also showed that the structure of pancreatic β-cells was damaged and the number of β-cells was changed in hyperuricemic rats while they were aggravated in rosuvastatin group.

Conclusion

Rosuvastatin has roles in inducing FGB, GADA, OGTT and pancreatic β-cells damage in hyperuricemic rats.

Cytoglobin attenuates pancreatic cancer growth via scavenging reactive oxygen species

Pancreatic cancer is a highly challenging malignancy with extremely poor prognosis. Cytoglobin (CYGB), a hemeprotein involved in liver fibrosis and cancer development, is expressed in pericytes of all organs. Here, we examined the role of CYGB in the development of pancreatic cancer. CYGB expression appeared predominately in the area surrounding adenocarcinoma and negatively correlated with tumor size in patients with pancreatic cancer. Directly injecting 7, 12-dimethylbenz[a]anthracene into the pancreatic tail in wild-type mice resulted in time-dependent induction of severe pancreatitis, fibrosis, and oxidative damage, which was rescued by Cygb overexpression in transgenic mice. Pancreatic cancer incidence was 93% in wild-type mice but only 55% in transgenic mice. Enhanced CYGB expression in human pancreatic stellate cells in vitro reduced cellular collagen synthesis, inhibited cell activation, increased expression of antioxidant-related genes, and increased CYGB secretion into the medium. Cygb-overexpressing or recombinant human CYGB (rhCYGB) -treated MIA PaCa-2 cancer cells exhibited dose-dependent cell cycle arrest at the G1 phase, diminished cell migration, and reduction in colony formation. RNA sequencing in rhCYGB-treated MIA PaCa-2 cells revealed downregulation of cell cycle and oxidative phosphorylation pathways. An increase in MIA PaCa-2 cell proliferation and reactive oxygen species production by H₂O₂ challenge was blocked by rhCYGB treatment or Cygb overexpression. PANC-1, OCUP-A2, and BxPC-3 cancer cells showed similar responses to rhCYGB. Known antioxidants N-acetyl cysteine and glutathione also inhibited cancer cell growth. These results demonstrate that CYGB suppresses pancreatic stellate cell activation, pancreatic fibrosis, and tumor growth, suggesting its potential therapeutic application against pancreatic cancer.

Targeting Fibrosis: The Bridge That Connects Pancreatitis and Pancreatic Cancer

Pancreatic fibrosis is caused by the excessive deposits of extracellular matrix (ECM) and collagen fibers during repeated necrosis to repair damaged pancreatic tissue. Pancreatic fibrosis is frequently present in chronic pancreatitis (CP) and pancreatic cancer (PC). Clinically, pancreatic fibrosis is a pathological feature of pancreatitis and pancreatic cancer. However, many new studies have found that pancreatic fibrosis is involved in the transformation from pancreatitis to pancreatic cancer. Thus, the role of fibrosis in the crosstalk between pancreatitis and pancreatic cancer is critical and still elusive; therefore, it deserves more attention. Here, we review the development of pancreatic fibrosis in inflammation and cancer, and we discuss the therapeutic strategies for alleviating pancreatic fibrosis. We further propose that cellular stress response might be a key driver that links fibrosis to cancer initiation and progression. Therefore, targeting stress proteins, such as nuclear protein 1 (NUPR1), could be an interesting strategy for pancreatic fibrosis and PC treatment.

Soy-tomato enriched diet reduces inflammation and disease severity in a pre-clinical model of chronic pancreatitis

Chronic pancreatitis (CP) is a fibro-inflammatory syndrome in individuals who develop persistent pathological responses to parenchymal injury or stress. Novel therapeutic or dietary interventions that could lessen inflammation in this disease could significantly improve quality of life in patients with CP. Complex dietary foods like soy and tomatoes are composed of active metabolites with anti-inflammatory effects. Data from our group reports that bioactive agents in soy and tomatoes can reduce pro-inflammatory cytokines and suppressive immune populations. Additionally, our team has developed a novel soy-tomato juice currently being studied in healthy individuals with no toxicities, and good compliance and bioavailability. Thus, we hypothesize that administration of a soy-tomato enriched diet can reduce inflammation and severity of CP. C57BL/6 mice were injected intraperitoneally with 50 μg/kg caeurlein (7 hourly injections, twice weekly) for 6 weeks to induce CP. After 4 weeks of caerulein injections, mice were administered a control or a soy-tomato enriched diet for 2 weeks. Disease severity was measured via immunohistochemical analysis of pancreata measuring loss of acini, fibrosis, inflammation, and necrosis. Serum lipase and amylase levels were analyzed at the end of the study. Inflammatory factors in the serum and pancreas, and immune populations in the spleen of mice were analyzed by cytokine multiplex detection, qRT-PCR, and flow cytometry respectively. Infra-red (IR) sensing of mice was used to monitor spontaneous activity and distress of mice. Mice fed a soy-tomato enriched diet had a significantly reduced level of inflammation and severity of CP (p = 0.032) compared to mice administered a control diet with restored serum lipase and amylase levels (p < 0.05). Mice with CP fed a soy-tomato diet had a reduction in inflammatory factors (TNF-α, IL-1β, IL-5) and suppressive immune populations (myeloid-derived suppressor cells; MDSC) compared to control diet fed mice (p < 0.05). Infra-red sensing to monitor spontaneous activity of mice showed that soy-tomato enriched diet improved total activity and overall health of mice with CP (p = 0.055) and CP mice on a control diet were determined to spend more time at rest (p = 0.053). These pre-clinical results indicate that a soy-tomato enriched diet may be a novel treatment approach to reduce inflammation and pain in patients with CP.

Pancreatic volume does not correlate with histologic fibrosis in adult patients with recurrent acute and chronic pancreatitis

OBJECTIVES

Reduced pancreatic volume, often referred to as atrophy, is a commonly reported imaging feature of chronic pancreatitis (CP). This study evaluated whether there is an association between pancreatic volume and fibrosis, the criterion standard of CP, in patients undergoing total pancreatectomy with islet autotransplantation (TPIAT) for recurrent acute pancreatitis (RAP) and CP.

METHODS

All adult patients who underwent TPIAT between 2010 and 2019 were categorized into 3 groups: RAP, definite CP and indeterminate CP. Pancreatic volume was calculated by summing up the areas from each thin section of the pancreas on 3D CT imaging. Excisional biopsies of the pancreatic head as well as body/tail region were obtained at the time of TPIAT. Two different fibrosis scores were used for histologic assessment.

RESULTS

A total of 16, 29 and 15 patients underwent TPIAT for RAP, definite CP and indeterminate CP, respectively. The mean pancreatic volumes for patients with RAP, definite CP and indeterminate CP were 65.7 ± 28.5 cc, 54.9 ± 22.9 cc and 61.8 ± 23.6 cc, respectively (p = 0.3). The mean fibrosis scores were significantly higher in patients with definite CP compared to RAP (p < 0.001) and indeterminate CP (p < 0.001). Pancreatic volume was not associated with either fibrosis score after adjusting for age, gender, duration of disease, BMI and diabetes in the multivariable analysis.

CONCLUSIONS

While the fibrosis scores were higher in definite CP compared to both RAP and indeterminate CP, there was no correlation between pancreatic volume and fibrosis. This suggests that atrophy alone cannot be used to diagnose CP.

Cerulein-induced chronic pancreatitis in Swiss albino mice: An improved short-term model for pharmacological screening

There is a need for short-term, reliable and reproducible animal model of chronic pancreatitis (CP) in small animals like mice. This study was aimed to establish the 9 exposures of cerulein-induced CP in mice. Repeated intraperitoneal cerulein injections were performed at 6 consecutive doses (50 μg/kg)/day, 3 days a week for 3 weeks to induce chronic pancreatitis in Swiss albino mice. The severity of damage was assessed by biochemical assays and histopathology. The expression of pro-inflammatory cytokine and fibrotic proteins was assessed by IHC and western blotting. The cerulein treated mice showed significantly elevated plasma amylase (p < .0285) and lipase levels (p < .0022) and resulted in significantly increased pancreatic oxidative (p < .0022) and nitrosative (p < .0022) stress. The hydroxyproline levels were 3.06 fold increased in the cerulein treated mice. The expressions of fibrotic cytokine TGF-β1 by 1.8 folds and pro-inflammatory cytokines TNF-α by 2.3 fold, IL-6 by 2.2 fold and IL-1β by 3.7 fold were markedly increased in cerulein treated mice. The histological evaluations indicated increased inflammatory cells infiltration and deposition of collagen. Moreover, the expression of fibrotic markers such as α-SMA increased by 2.5 folds (p < .00014), collagen1a by 1.3 folds (p < .0258) and fibronectin by 3.5 folds (p < .00014) were significantly increased. Our study demonstrates the superiority of 9 exposures of cerulein-induced CP model in mice with the reduction of duration, cerulein exposure, more economical and mortality rate of mice over the available models. Therefore, our model may be suitable to evaluate the pharmacological effects of new drugs in chronic pancreatitis.

β-Cell Dedifferentiation in Patients With T2D With Adequate Glucose Control and Nondiabetic Chronic Pancreatitis

CONTEXT

Type 2 diabetes (T2D) and pancreatogenic diabetes are both associated with loss of functional β-cell mass. Previous studies have proposed β-cell dedifferentiation as a mechanism of islet β-cell failure, but its significance in humans is still controversial.

OBJECTIVE

To determine whether β-cell dedifferentiation occurs in human T2D with adequate glucose control and in nondiabetic chronic pancreatitis (NDCP), we examined pancreatic islets from nine nondiabetic controls, 10 patients with diabetes with well-controlled fasting glycemia, and four individuals with NDCP.

DESIGN

We calculated the percentage of hormone-negative endocrine cells and multihormone endocrine cells and scored the pathological characteristics; that is, inflammatory cell infiltration, fibrosis, atrophy, and steatosis, in each case.

RESULTS

We found a nearly threefold increase in dedifferentiated cells in T2D with adequate glucose control compared with nondiabetic controls (10.0% vs 3.6%, T2D vs nondiabetic controls, P < 0.0001). The dedifferentiation rate was positively correlated with the duration of diabetes. Moreover, we detected a considerable proportion of dedifferentiated cells in NDCP (10.4%), which correlated well with the grade of inflammatory cell infiltration, fibrosis, and atrophy.

CONCLUSIONS

The data support the view that pancreatic β-cells are dedifferentiated in patients with T2D with adequate glucose control. Furthermore, the existence of abundant dedifferentiated cells in NDCP suggests that inflammation-induced β-cell dedifferentiation can be a cause of pancreatogenic diabetes during disease progress.

Transgenic expression of cyclooxygenase-2 in pancreatic acinar cells induces chronic pancreatitis

Replacement of the exocrine parenchyma by fibrous tissue is a main characteristic of chronic pancreatitis. Understanding the mechanisms of pancreatic fibrogenesis is critical for the development of preventive and therapeutic interventions. Cyclooxygenase-2 (COX-2), a rate-limiting enzyme for prostaglandin synthesis, is expressed in patients with chronic pancreatitis. However, it is unknown whether COX-2 can cause chronic pancreatitis. To investigate the roles of pancreatic acinar COX-2 in fibrogenesis and the development of chronic pancreatitis, COX-2 was ectopically expressed specifically in pancreatic acinar cells in transgenic mice. Histopathological changes and expression levels of several profibrogenic factors related to chronic pancreatitis were evaluated. COX-2 was expressed in the pancreas of the transgenic mice, as detected by Western blot analysis. Immunohistochemical staining showed COX-2 was specifically expressed in pancreatic acinar cells. COX-2 expression led to progressive changes in the pancreas, including pancreas megaly, persistent inflammation, collagen deposition, and acinar-to-ductal metaplasia. Quantitative RT-PCR and immunostaining showed that profibrogenic factors were upregulated and pancreatic stellate cells were activated in the COX-2 transgenic mice. Expression of COX-2 in pancreatic acinar cells is sufficient to induce chronic pancreatitis. Targeting this pathway may be valuable in the prevention of chronic pancreatitis. NEW & NOTEWORTHY COX-2 expression is observed in pancreatic tissues of human chronic pancreatitis. In this study, we showed that COX-2 expression caused the development of chronic pancreatitis in transgenic mice, supporting the idea that COX-2 inhibition may be an effective preventive and therapeutic strategy.

Inonotus obliquus polysaccharide regulates gut microbiota of chronic pancreatitis in mice

Polysaccharide is efficient in attenuation of metabolic ailments and modulation of gut microbiota as prebiotics. The therapeutic effect of Inonotus obliquus polysaccharide (IOP) on chronic pancreatitis (CP) in mice has been validated in our previous study. However, it is not clear whether IOP is conducive to maintaining the homeostasis between gut microbiota and host. The aim of this study is to testify the potential effects of IOP on gut microbiota composition and diversity in mice with CP. The changes in glutathione peroxidase (GSH-P_X), total antioxidant capacity (TAOC), tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-β), lipase and trypsin levels were measured by commercial assay kits, meanwhile the gut microbiota composition and diversity were analyzed by high throughput sequencing. The IOP treatment increased GSH-P_X and TAOC levels, and decreased TNF-α, TGF-β, lipase and trypsin levels in CP mice. It was also observed that gut microbiota in IOP treated groups were less diverse than others in terms of lower Shannon diversity index and Chao 1 estimator. IOP increased the proportion of Bacteroidetes and decreased that of Firmicutes at phylum level. Bacteroidetes was found positively correlated with GSH-P_X and TAOC, and Firmicutes correlated with TNF-α, TGF-β, and lipase. In conclusion, administration of IOP could regulate gut microbiota composition and diversity to a healthy profile in mice with CP, and some bacterial phylum significantly correlated with characteristic parameters.

Targeting reactive oxygen species in development and progression of pancreatic cancer

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDA) is characterized by expression of oncogenic KRas which drives all aspects of tumorigenesis. Oncogenic KRas induces the formation of reactive oxygen species (ROS) which have been implicated in initiation and progression of PDA. To facilitate tumor promoting levels and to avoid oncogene-induced senescence or cytotoxicity, ROS homeostasis in PDA cells is balanced by additional up-regulation of antioxidant systems. Areas covered: We examine the sources of ROS in PDA, the mechanisms by which ROS homeostasis is maintained, and the biological consequences of ROS in PDA. Additionally, we discuss the potential mechanisms for targeting ROS homoeostasis as a point of therapeutic intervention. An extensive review of the relevant literature as it relates to the topic was conducted using PubMed. Expert commentary: Even though oncogenic mutations in the KRAS gene have been detected in over 95% of human pancreatic adenocarcinoma, targeting its gene product, KRas, has been difficult. The dependency of PDA cells on balancing ROS homeostasis could be an angle for new prevention or treatment strategies. These include use of antioxidants to prevent formation or progression of precancerous lesions, or methods to increase ROS in tumor cells to toxic levels.

Effects of Ganoderma lucidum polysaccharides on chronic pancreatitis and intestinal microbiota in mice

This study manifested the effects of polysaccharides from Ganoderma lucidum strain S₃ (GLP S₃) on chronic pancreatitis (CP) therapy and intestinal microbiota modulation in mice induced by diethyldithiocarbamate (DDC). The GLPS₃ was prepared from cultured mycelium and markedly alleviated the pancreatitis in mice through decreasing lipase, AMS, IFN-γ and TNF-α level as well as increasing SOD and total antioxidant activity. Furthermore, high throughput sequencing analysis revealed that GLPS₃ altered the composition and diversity of intestinal microbiota, especially, decreased the relative abundance of phylum Bacteroidetes and increased that of phylum Firmictutes. At the genus level, supplementation of GLPS₃ increased the relative abundance of the beneficial bacteria such as Lactobacillales, Roseburia and Lachnospiraceae. These results disclosed the potential therapy mechanism of GLPS₃ on chronic pancreatitis might be intestinal microbiota dependent.

Effects of panax notoginseng saponins on the osteogenic differentiation of rabbit bone mesenchymal stem cells through TGF-β1 signaling pathway

Background

Panax Notoginseng is a well-known Chinese medicinal herb which has been used in China for treatment of bone fracture for hundreds of years. However, the specific biological mechanisms of osteogenic effect of PNS are not well understood.

Methods

In this study, newborn rabbit BMSCs were isolated, and then identified by the positive expression rates of cell surface markers, including CD29, CD45 and HLA-DR, which were detected by flow cytometry(FCM). After the lentivirus-induced cell model of TGF-β1 gene silencing was established, the interference efficiency was tested by q-PCR and Western blot, and the growth curve of silencing cells was drawn by MTT so as to grasp the growth rhythm of silencing cells. In the alizarin red-staining experiment, the effect of 100 mg/L PNS on the activity of intracellular ALP of TGF-β1 gene silencing BMSCs was detected, so as to observe the effect of 100 mg/L PNS on the formation of calcium nodes of gene silencing BMSCs.

Results

By separating rabbit BMSCs, the lentivirus-induced cell model of TGF-β1 gene silencing was established. Both TGF-β1 mRNA and protein expression were restrained significantly, and the target gene kept silence stably via the verification of q-PCR and Western blot; there was no significant differences of the growth curve between RNAi cells and normal cells; the activity of intracellular APL in 100 mg RNAi group was obviously lower than that in 100 mg group (p < 0.05), but higher than that in the normal group; in the alizarin red-staining experiment, it focused on the effects of PNS on the formation of calcium nodes of gene silencing BMSCs, which showed that calcium nodes could be formed in 100 mg RNAi group but its quantity was lower than that of 100 mg group (p < 0.05).

Conclusions

It was shown that silencing TGF-β1 gene could interrupt the osteogenic effects of PNS. PNS may have a promoting effect on osteogenic differentiation of rabbits’ BMSCs in vitro by up-regulating the gene expression of TGF-β1.

Antioxidant activity of Inonotus obliquus polysaccharide and its amelioration for chronic pancreatitis in mice

Inonotus obliquus polysaccharide (IOP) was extracted by water with a yield of 9.83% and purified by an anion-exchange DEAE cellulose column and Sephadex G-200 gel with a polysaccharide content of 98.6%. The scavenging activities for 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and hydroxyl radicals of IOP were 82.3% and 81.3% respectively at a concentration of 5 mg/mL. IOP was composed of Man, Rha, Glu, Gal, Xyl and Ara in a molar ratio of 9.81:3.6：29.1：20.5：21.6：5.4 respectively. The gel permeation chromatography indicated that IOP was a homogeneous polysaccharide with molecular weight of 32.5 kDa. IOP helped to alleviate pancreatic acinar atrophy and weight loss for chronic pancreatitis (CP) mice induced by Diethyldithiocarbamate (DDC). The SOD level was increased most by IOP-H treatment (400 mg/kg body weight). MDA, IL-1β and LDH were significantly decreased by IOP treatment, especially hydroxyproline, IFN-γ and AMS levels were decreased 39.18%, 37.82% and 41.57% by IOP-H treatment respectively compared to MC group. In conclusion, IOP possessed strong antioxidant activity for scavenging free radicals in vitro and vivo which could be propitious to CP therapy in mice.

Decreased serum paraoxonase activity in patients with chronic pancreatitis

BACKGROUND

Recent evidences suggest that oxidative stress is involved in the mechanism of chronic pancreatitis (CP). Paraoxonase 1 (PON1) plays an important role as an endogenous free-radical scavenging molecule. The aim of our study is to investigate whether serum PON1 activity is associated with the presence of CP.

METHODS

A total of 186 patients with alcoholic CP and 132 healthy subjects were enrolled in this study. Serum PON1 activity was measured using paraoxon as a substrate.

RESULTS

Serum PON1 activity was significantly decreased in CP patients compared with healthy subjects. Multivariable logistic regression analysis revealed that serum PON1 activity was a determinant of the presence of CP (OR = 0.992, 95% CI = 0.987-0.998; P = 0.006).

CONCLUSIONS

Decreased serum PON1 activity may be considered as a predicting marker of the presence of CP.

Pancreatic stellate cells: a starring role in normal and diseased pancreas

While the morphology and function of cells of the exocrine and endocrine pancreas have been studied over several centuries, one important cell type in the gland, the pancreatic stellate cell (PSC), had remained undiscovered until as recently as 20 years ago. Even after its first description in 1982, it was to be another 16 years before its biology could begin to be studied, because it was only in 1998 that methods were developed to isolate and culture PSCs from rodent and human pancreas. PSCs are now known to play a critical role in pancreatic fibrosis, a consistent histological feature of two major diseases of the pancreas—chronic pancreatitis and pancreatic cancer. In health, PSCs maintain normal tissue architecture via regulation of the synthesis and degradation of extracellular matrix (ECM) proteins. Recent studies have also implied other functions for PSCs as progenitor cells, immune cells or intermediaries in exocrine pancreatic secretion in humans. During pancreatic injury, PSCs transform from their quiescent phase into an activated, myofibroblast-like phenotype that secretes excessive amounts of ECM proteins leading to the fibrosis of chronic pancreatitis and pancreatic cancer. An ever increasing number of factors that stimulate and/or inhibit PSC activation via paracrine and autocrine pathways are being identified and characterized. It is also now established that PSCs interact closely with pancreatic cancer cells to facilitate cancer progression. Based on these findings, several therapeutic strategies have been examined in experimental models of chronic pancreatitis as well as pancreatic cancer, in a bid to inhibit/retard PSC activation and thereby alleviate chronic pancreatitis or reduce tumor growth in pancreatic cancer. The challenge that remains is to translate these pre-clinical developments into clinically applicable treatments for patients with chronic pancreatitis and pancreatic cancer.

The fibrosis of chronic pancreatitis: new insights into the role of pancreatic stellate cells

SIGNIFICANCE

Prominent fibrosis is a major histological feature of chronic pancreatitis, a progressive necroinflammatory condition of the pancreas, most commonly associated with alcohol abuse. Patients with this disease often develop exocrine and endocrine insufficiency characterized by maldigestion and diabetes. Up until just over a decade ago, there was little understanding of the pathogenesis of pancreatic fibrosis in chronic pancreatitis.

RECENT ADVANCES

In recent times, significant progress has been made in this area, mostly due to the identification, isolation, and characterization of the cells, namely pancreatic stellate cells (PSCs) that are now established as key players in pancreatic fibrogenesis. In health, PSCs maintain normal tissue architecture via regulation of the synthesis and degradation of extracellular matrix (ECM) proteins. During pancreatic injury, PSCs transform into an activated phenotype that secretes excessive amounts of the ECM proteins that comprise fibrous tissue.

CRITICAL ISSUES

This Review summarizes current knowledge and critical aspects of PSC biology which have been increasingly well characterized over the past few years, particularly with respect to the response of PSCs to factors that stimulate or inhibit their activation and the intracellular signaling pathways governing these processes. Based on this knowledge, several therapeutic strategies have been examined in experimental models of pancreatic fibrosis, demonstrating that pancreatic fibrosis is a potentially reversible condition, at least in early stages.

FUTURE DIRECTIONS

These will involve translation of the laboratory findings into effective clinical approaches to prevent/inhibit PSC activation so as to prevent, retard, or reverse the fibrotic process in pancreatitis.

Treatment with pravastatin attenuates progression of chronic pancreatitis in rat

As appropriate therapies for pancreatic fibrosis and inflammation are limited, prognosis of chronic pancreatitis has not improved to date. Recent studies have shown that statins improve inflammation and fibrosis in several organs. We therefore examined the therapeutic effect of pravastatin on progression of chronic pancreatitis by starting this treatment after induction of pancreatic fibrosis in rats. Chronic pancreatitis was induced by continuous pancreatic ductal hypertension (PDH) for 14 days according to our previous study. Pravastatin at a dose of 10 mg/kg/day was administrated directly into the duodenum via cannula from 2 days after induction of PDH. Progression of pancreatic fibrosis and expression levels of transforming growth factor-β1 and tumor necrosis factor-α mRNA were markedly attenuated after commencement of pravastatin compared with untreated group with PDH. In addition, pravastatin treatment markedly improved pancreatic exocrine function and significantly elevated expression level of interleukin (IL)-10 and superoxide dismutase activity in the pancreas compared with the untreated group with PDH. These results revealed that pravastatin substantially attenuates the progression of pancreatic inflammation, fibrosis and exocrine dysfunction probably by its anti-oxidative property and overproduction of IL-10 in animal model of chronic pancreatitis. These results provide an experimental evidence that pravastatin exerts beneficial effect for progression of chronic pancreatitis.

Assessment of oxidative status in chronic pancreatitis and its relation with zinc status

BACKGROUND

Oxidative stress-induced free radicals have been implicated in the pathology of chronic pancreatitis (CP).

AIM

We aimed to estimate oxidative stress and antioxidant status in tropical chronic pancreatitis (TCP) and alcoholic chronic pancreatitis (ACP) and correlate with zinc status.

METHODS

One hundred and seventy-five CP patients (91 TCP, 84 ACP) and 113 healthy subjects were prospectively studied. Disease characteristics and imaging features were recorded. Erythrocyte reduced glutathione, glutathione peroxidase (GPx), superoxide dismutase (SOD), plasma vitamin C, and erythrocyte thiobarbituric acid reactive substance (TBARS) were estimated by spectrophotometry. Erythrocyte zinc was estimated by flame atomic absorption spectrophotometry.

RESULTS

Enhanced lipid peroxidation with concomitant decrease in antioxidant status was observed in both TCP and ACP patients (p < 0.05). The findings were comparable in both diabetic and non-diabetic CP patients. Significantly, lower plasma vitamin C and elevated levels of erythrocyte TBARS was noted in TCP as compared to ACP patients. The erythrocyte zinc significantly correlated with SOD activity (r = 0.450, p < 0.001).

CONCLUSIONS

Our study corroborates the role of oxidative stress in CP and suggests some differences in oxidative status in TCP and ACP patients. Zinc deficiency appears to affect oxidative status in CP patients.

α-Tocopherol treatment ameliorates chronic pancreatitis in an experimental rat model induced by trinitrobenzene sulfonic acid

OBJECTIVE

To investigate the effects of α-tocopherol on pancreatic fibrosis and survival in rats with experimental chronic pancreatitis induced by trinitrobenzene sulfonic acid (TNBS).

METHODS

Chronic pancreatitis was induced in male Sprague-Dawley rats by infusion of TNBS into the pancreatic duct. α-Tocopherol (300, 600 or 900 mg/kg) was orally administered to rats with experimental pancreatitis (treatment group) daily for 4 weeks. The relative pancreatic weight, pancreatic pseudocyst and death rate were observed. Paraffin-embedded tissue samples were sliced, stained by hematoxylin-eosin and histopathologically examined.

RESULTS

α-Tocopherol administration significantly ameliorated the pancreatic weight loss induced by TNBS in chronic pancreatitis rats compared to the control group. There were pancreatic pseudocysts in 69% of the α-tocopherol group, and in 100% of the control group. α-Tocopherol administration led to a significant increase of the survival rate. The histopathologic scores were higher in the control group than in the α-tocopherol group. Subgroup analysis of histopathologic scores revealed that a high dose of α-tocopherol results in less pancreatic injuries.

CONCLUSION

α-Tocopherol treatment elevates survival rate, extenuates fibrosis and increases relative pancreatic weight in the chronic pancreatitis model. α-Tocopherol therapy in chronic pancreatitis is now required to confirm these findings and establish the role of this treatment in the management of this disabling condition. and IAP.

Treatment with oxymatrine down-regulates TGFβRII expression in chronic pancreatitis in rats

AIM: To investigate the effect of treatment with oxymatrine on the expression of transforming growth factor β1 type II receptor (TGFβRII) in chronic pancreatitis (CP) in rats and to explore the potential anti-fibrotic mechanism of oxymatrine.

METHODS: Forty male Wistar rats were randomly and equally assigned to four groups: negative control group (NC), CP group, oxymatrine treatment group (OT), and oxymatrine prevention group (OP). Each group was further divided into two subgroups for detection at different time points. Except the NC group, pancreatic fibrosis was induced in rats of the other groups by intraperitoneal injections of diethyldithiocarbamate (DDC 700 mg/kg). Preventive and therapeutic oxymatrine (100 mg/kg) was given to rats of the OT and OP group, respectively. Pancreatic tissue samples were taken for HE and Masson staining to evaluate histological alterations. The expression of TGFβRII in pancreatic tissue was detected by Western blot.

RESULTS: The contents of collagen fibers in the CP group were significantly higher than those in the other groups (day 20: 22.54% ± 4.45% vs 13.16% ± 1.84%, 19.58% ± 2.78%, 2.45% ± 0.24%; day 40: 35.14% ± 3.27% vs 25.14% ± 3.67%, 28.68% ± 2.55%, 3.0% ± 0.32%; all P < 0.05), and the percentages of collagen area in the OP and OT groups on day 40 were significantly higher than those on day 20 (25.14% ± 3.67% vs 13.16% ± 1.84%; 28.68% ± 2.55% vs 19.58% ± 2.78%; all P < 0.05) The expression level of TGFβRII in the CP group was significantly higher than those in the other groups (day 20: 0.74 ± 0.05 vs 0.47 ± 0.03, 0.61 ± 0.03, 0.21 ± 0.02; day 40: 1.01 ± 0.14 vs 0.64 ± 0.08, 0.75 ± 0.04, 0.23 ± 0.03; all P < 0.05). The expression levels of TGFβRII in the OP and OT groups on day 40 were significantly higher than those on day 20 (0.64 ± 0.08 vs 0.47 ± 0.03; 0.75 ± 0.04 vs 0.61 ± 0.03; all P < 0.05).

CONCLUSION: Treatment with oxymatrine exerts beneficial effects against CP possibly by inhibiting TGFβRII signaling.

Oxymatrine enhances the expression of collagen I and α-SMA in rat chronic pancreatitis

AIM: To investigate the treatment effects of oxymatrine (OM) against chronic pancreatitis in rats and to explore the potential mechanisms involved.

METHODS: Forty healthy Wistar rats were randomly and equally divided into four groups: negative control group (NC group), CP model group (CP group), OM treatment group (OT group), and OM pretreatment group (OP group), which received saline qod, diethyldithiocarbamate (DDC) at 700 mg/kg qod, diethyldithiocarbamate (DDC) at 700 mg/kg qod and OM at 100 mg/kg a week later, and diethyldithiocarbamate (DDC) at 700 mg/kg qod and OM at 100 mg/kg simultaneously, respectively. Thirty days later, DDC injection was discontinued, while OM treatment continued. Rats were executed on days 20 and 40 (n = 5 at each time point). Collagen fibers were stained by Masson's trichrome. The localization and expression of collagen I and α-SMA in chronic pancreatitis were examined by immunohistochemistry.

RESULTS: Collage I was localized in the periphery of the pancreas in the NC group. In the CP group, collagen I could also be seen in periacinar and perilobular areas. The immunoreactivity of α-SMA was detected in the blood vessel wall in the NC group, and in the blood vessel wall and periacinar area in the CP group. The expression of collagen I and α-SMA in periacinar area was significantly lower in the OP and OT groups than in the CP group. The percentages of collagen area on days 20 and 40 were significantly lower in the NC group (3.0% ± 0.32% and 2.45% ± 0.24%) than in the other groups (all P < 0.05), but significantly higher in the CP group (22.54% ± 4.45% and 35.14% ± 3.27%) than in the OP group (13.16% ± 1.84% and 25.14% ± 3.67%) and the OT group (19.58% ± 2.78% and 28.68% ± 2.55%). The percentages of collagen areas on day 40 in the CP and OT groups were significantly higher than those on day 20 (both P < 0.05). The relative expression levels of α-SMA on days 20 and 40 were significantly higher in the CP group (1.06 ± 0.04 and 1.16 ± 0.03) than in other groups (all P < 0.05). The NC group had the lowest relative expression level of α-SMA (0.73 ± 0.06 and 0.78 ± 0.06). No significant difference was noted in the relative expression level of α-SMA between the OT and OP groups.

CONCLUSION: The expression of collagen I and α-SMA is enhanced in rat CP, predominantly localized in perivascular, periacinar and perilobular areas. OM can decrease collagen production and pancreatic stellate cell activation and thereby inhibit the development of pancreatic fibrosis.

Effect of long- and short-term treatments with pravastatin on diabetes mellitus and pancreatic fibrosis in the Otsuka-Long-Evans-Tokushima fatty rat

BACKGROUND AND PURPOSE

The effects of statins on diabetes mellitus (DM) are controversial, and their effects on pancreatic fibrosis are poorly defined. We investigated the effect of long- and short-term treatments with pravastatin on the development of DM and pancreatic fibrosis in DM-prone Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats.

EXPERIMENTAL APPROACH

Male OLETF rats were divided into four groups at 12 weeks of age. The first group received a standard rat diet until the end of the experimental period at age 80 weeks. The second group was given a diet containing 0.05% pravastatin from 12 weeks of age, before the onset of DM and pancreatic fibrosis, and the third group was given the same pravastatin diet from 28 weeks of age, after the onset of DM and pancreatic fibrosis, until age 80 weeks. The fourth group received the same pravastatin diet only for 16 weeks, from 12 to 28 weeks of age, and switched to a standard diet. Progressions of DM and pancreatic fibrosis were evaluated.

KEY RESULTS

Long-term treatments with pravastatin, either from 12 or 28 weeks of age, decreased serum glucose concentration and fibrotic area, elevated superoxide dismutase activity and down-regulated transforming growth factor-beta1 mRNA in the pancreas. In contrast, after a short-term treatment with pravastatin, these parameters markedly deteriorated after its cessation.

CONCLUSIONS AND IMPLICATIONS

The results suggest that long-term treatment with pravastatin improves DM and pancreatic fibrosis via anti-oxidative and anti-fibrotic properties, whereas cessation of pravastatin abolishes these beneficial effects, and accelerates DM and pancreatic fibrosis.

Effect of Korean red ginseng on superoxide dismutase inhibitor-induced pancreatitis in rats: a histopathologic and immunohistochemical study

OBJECTIVES

Korean red ginseng (KRG) is a representative herbal remedy in Korea. We examined the effects of KRG treatment on superoxide dismutase inhibitor-induced experimental pancreatitis.

METHODS

Sprague-Dawley rats and KRG from the roots of a 6-year-old fresh Panax ginseng C. A. Meyer plant were used in this study. Pancreatitis was induced by intraperitoneal injection of diethyldithiocarbamate for 4 weeks. Korean red ginseng was fed orally to rats for the next 3 weeks. At week 7, all rats were killed, and pancreatic tissues were analyzed.

RESULTS

No histological alterations were detected in the pancreata of normal and KRG control groups. Tissues from the non-KRG-treated pancreatitis group exhibited marked pancreatic damage including changes in histological architecture, acinar cell necrosis and degeneration, and cytoplasmic vacuolization. However, tissues from the KRG-treated pancreatitis group exhibited no cellular damage and had normal histological pancreatic architecture. Immunohistochemical examination revealed that the expressions of nuclear factor kappaB, tumor necrosis factor alpha, inducible nitric oxide synthase, and the oxidant stress markers, malondialdehyde and 4-hydroxynonenal, were significantly decreased in the KRG-treated pancreatitis group as compared with the non-KRG-treated pancreatitis group.

CONCLUSIONS

Our results suggest that KRG has antioxidant therapeutic effects on superoxide dismutase inhibitor-induced pancreatitis by inhibition of nuclear factor kappaB.

Protective effect of salvianolic acid B on chronic pancreatitis induced by trinitrobenzene sulfonic acid solution in rats

OBJECTIVES

To investigate the effects of salvianolic acid B (Sal-B) on pancreatic damage in experimental chronic pancreatitis.

METHODS

Chronic pancreatitis was induced by infusion of trinitrobenzene sulfonic acid into the pancreatic duct in male Sprague-Dawley rats. From the beginning of 5 weeks, the rats in group 2 were treated with Sal-B by gavage for 8 weeks. Salvianolic acid B was given at a daily dose of 10 mg/kg body weight. At the end of 12 weeks, the levels of serum biochemical indexes were measured on an automatic biochemical analyzer; serum hyaluronic acid and laminin levels were determined by radioimmunoassay; pancreatic tissue malondialdehyde (MDA) was analyzed, and the degree of pancreatic damage was determined.

RESULTS

The level of serum biochemical indexes were similar in all groups (P > 0.05 for all). Salvianolic acid B treatment did not obviously reduce hyaluronic acid and laminin concentration in blood (P > 0.05). Salvianolic acid B treatment decreased MDA concentration in pancreatic tissue (P < 0.01). Salvianolic acid B clearly improved pancreatic histological findings and prevented the activation of pancreatic stellate cells.

CONCLUSIONS

Sal-B treatment decreased MDA concentration in pancreatic tissue, attenuated morphological pancreatic damage, and prevented the activation of pancreatic stellate cells in experimental chronic pancreatitis.

Ascorbic acid alleviates pancreatic damage induced by dibutyltin dichloride (DBTC) in rats

PURPOSE

Because previous studies have reported depleted antioxidant capacity in patients with chronic pancreatitis (CP), prevention of free radical production has gained importance in antifibrotic treatment strategies for CP. The aim of this study was to investigate the effects of ascorbic acid on oxidative capacity and pancreatic damage in experimental CP.

MATERIALS AND METHODS

CP was induced in male Sprague-Dawley rats by infusion of dibutyltin dichloride (DBTC) into the tail vein. Ascorbic acid was given intraperitoneally at a daily dose of 10 mg/kg body weight. The treatment groups were as follows: group 1, DBTC plus intraperitoneal physiologic saline; group 2, DBTC plus intraperitoneal ascorbic acid; group 3, solvent plus intraperitoneal physiologic saline; group 4, no operation plus intraperitoneal physiologic saline. Each group contained 15 animals. Treatment was started after CP was established. After 4 weeks of treatment, serum hyaluronic acid and laminin levels were determined by radioimmunoassay, pancreatic tissue oxidative stress was analyzed, and the degree of pancreatic damage was determined.

RESULTS

Ascorbic acid treatment markedly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) concentrations in pancreatic tissue (p < 0.01 for both). Significant serum hyaluronic acid and laminin reductions were observed in group 2 as compared with group 1 (p < 0.05). However, the serum hyaluronic acid and laminin levels remained elevated when compared with those of groups 3 and 4 (p < 0.05). Histopathologic scores were also lower in animals with CP that underwent ascorbic acid-treatment (p < 0.05).

CONCLUSION

Ascorbic acid treatment alleviated the degree of oxidative stress and pancreatic damage in rat CP. Antioxidant treatment might be considered a potential option to improve the pathologic process in CP.

Allopurinol in rat chronic pancreatitis: effects on pancreatic stellate cell activation

OBJECTIVES

Activation of pancreatic stellate cells (PSCs) is a key event in pancreatic fibrosis. Xanthine oxidase-derived free radicals are involved in the mechanism of chronic pancreatitis (CP). We here searched the in vivo effects of allopurinol on PSC activation and its relation to tissue oxidative stress and histological findings in rat CP.

METHODS

Rat CP was induced with intraductal trinitrobenzene sulfonic acid in groups 1 (n = 16) and 2 (n = 10). Group 3 (n = 10) received intraductal saline. Four weeks after induction, group 1 received allopurinol (200 mg/kg, s.c.), and groups 2 and 3 received saline. After 4 weeks, oxidative stress parameters, histological evaluation, and immunostaining for alpha-smooth muscle actin (+) PSCs were performed in the pancreata.

RESULTS

Oxidative stress parameters improved significantly in group 1 compared with groups 2 and 3. Collagen deposition and lobular/sublobular atrophy were significantly lower in group 1 than in group 2. Alpha-smooth muscle actin (+) PSCs counts in group 1 were significantly lower than in group 2, and were in correlation with the degree of fibrosis and atrophy.

CONCLUSIONS

Allopurinol inhibits PSC activation in vivo. Pancreatic fibrosis can be prevented, at least in part, by antioxidant treatment through xanthine oxidase metabolism. Long-term use of allopurinol and its analogs may be considered in clinical trials with CP.

Effects of epigallocatechin gallate on diethyldithiocarbamate-induced pancreatic fibrosis in rats

Epigallocatechin gallate (EGCG), a major component of green tea extracts, is known to have anti-fibrotic properties in many organs. The aim of present study was to investigate effects of EGCG on rat pancreatic fibrosis induced by diethyldithiocarbamate (DDC). Oral gavages of different dose of EGCG (50, 100 and 200 mg/kg daily for 8 weeks) ameliorated histological changes and significantly suppressed collagen deposition in a dose-dependent manner. Meanwhile, administration of EGCG inhibited overexpression of TGF-beta1 and alpha-smooth muscle actin (a symbol of activation of pancreatic stellate cells). Moreover, EGCG has a potent influence on expression of Smads (downstream transcription factor of TGF-beta1). EGCG suppressed the expression of Smad3 and enhanced the expression of Smad7. In conclusion, our results demonstrated that EGCG attenuated rat pancreatic fibrosis induced by DDC and therefore may be an anti-fibrogenic candidate in the pancreatic fibrosis.

Chronic pancreatitis: challenges and advances in pathogenesis, genetics, diagnosis, and therapy

Chronic pancreatitis (CP) is characterized by progressive pancreatic damage that eventually results in significant impairment of exocrine as well as endocrine functions of the gland. In Western societies, the commonest association of chronic pancreatitis is alcohol abuse. Our understanding of the pathogenesis of CP has improved in recent years, though important advances that have been made with respect to delineating the mechanisms responsible for the development of pancreatic fibrosis (a constant feature of CP) following repeated acute attacks of pancreatic necroinflammation (the necrosis-fibrosis concept). The pancreatic stellate cells (PSCs) are now established as key cells in fibrogenesis, particularly when activated either directly by toxic factors associated with pancreatitis (such as ethanol, its metabolites or oxidant stress) or by cytokines released during pancreatic necroinflammation. In recent years, research effort has also focused on the genetic abnormalities that may predispose to CP. Genes regulating trypsinogen activation/inactivation and cystic fibrosis transmembrane conductance regulator (CFTR) function have received particular attention. Mutations in these genes are now increasingly recognized for their potential 'disease modifier' role in distinct forms of CP including alcoholic, tropical, and idiopathic pancreatitis. Treatment of uncomplicated CP is usually conservative with the major aim being to effectively alleviate pain, maldigestion and diabetes, and consequently, to improve the patient's quality of life. Surgical and endoscopic interventions are reserved for complications such as pseudocysts, abscess, and malignancy.

Assessment of oxidative stress in chronic pancreatitis patients

AIM: To assess the levels of antioxidant capacity and oxidative damage in blood of chronic pancreatitis (CP) patients in comparison with those in healthy control subjects, by using several different analytical techniques.

METHODS: Thirty-five CP patients and 35 healthy control subjects were investigated prospectively with respect to plasma levels of thiols, ferric reducing ability of plasma (FRAP, i.e. antioxidant capacity), levels of protein carbonyls and thiobarbituric acid reactive substances (TBARS). Additionally, we evaluated the production of reactive oxygen species (ROS) in whole blood.

RESULTS: The antioxidative thiols including cysteine, cysteinylglycine and glutathione were significantly lower in CP patients. In addition, the non-enzymatic antioxidant capacity was significantly lower in CP patients, which correlated with the amount of oxidative protein (protein carbonyls) and the extent of lipid damage (TBARS), both were significantly higher in CP patients. The ROS production in whole blood after stimulation with phorbol 12-myritate 13-acetaat, demonstrated a strong tendency to produce more ROS in CP patients.

CONCLUSION: Oxidative stress may contribute to the pathogenesis of chronic pancreatitis by decreasing antioxidant capacity and increasing oxidative damage in CP patients may be a rationale for intervention with antioxidant therapy.

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Antioxidant treatment with taurine ameliorates chronic pancreatitis in an experimental rat model

OBJECTIVES

Based on the results of recent studies that reported depleted antioxidant capacity in patients with chronic pancreatitis (CP), prevention of free radical production has gained importance in antifibrotic treatment strategies in CP. The aim of this study was to investigate the effects of taurine on oxidative capacity and fibrosis in experimental chronic rat pancreatic fibrosis.

METHODS

CP was induced in male Sprague-Dawley rats by intraductal trinitrobenzene sulfonic acid (TNBS) dissolved in ethanol. Taurine was given intraperitoneally at a concentration of 1000 mg/kg. The treatment groups were as follows: group 1, TNBS plus normal saline (NS); group 2, TNBS plus taurine; group 3, ethanol plus NS; and group 4, NS plus NS. Each group contained 15 animals. Treatment was started after established CP. After 4 weeks of treatment, markers of oxidative stress and the degree of pancreatic fibrosis were determined.

RESULTS

The amount of weight loss was significantly lower in the taurine-treated group with CP (P < 0.002). Tissue malondialdehyde levels increased and superoxide dismutase and glutathione peroxidase activities decreased significantly after treatment as well (P < 0.001). Histopathologic scores were also lower in taurine-treated animals with CP (P < 0.005).

CONCLUSIONS

Taurine treatment improved the degree of oxidative stress and fibrosis in rat CP. Antioxidant treatment might be considered a novel option to alleviate the fibrotic process in CP.

Xanthine oxidase-derived free radicals directly activate rat pancreatic stellate cells

BACKGROUND AND AIM

Free radicals are reported to be associated with fibrosis in the pancreas. It is generally accepted that pancreatic stellate cells (PSC) play an important role in pancreatic fibrosis. However, the exact role of free radicals in activation of PSC has not been fully elucidated. In the present study, using a superoxide dismutase (SOD) inhibitor, diethyldithiocarbamate (DDC) with cultured PSC, we investigated how free radicals act on the activation of PSC.

METHODS

PSC were isolated from male Wister rats. Cultured rat PSC were incubated with DDC for 48 h. Intracellular SOD activity and lipid peroxidation were examined in DDC-treated PSC. Activation of PSC was examined by determining the expression of alpha-smooth muscle actin (alpha-SMA) by immunocytochemistry. The number of PSC using a hemocytometer, type I collagen secretion with ELISA and matrix metalloproteinases (MMP) activities with gelatin zymography were also examined. Secretion of transforming growth factor-beta1 (TGF-beta1) was evaluated by ELISA. The effects of the allopurinol, a xanthine oxidase (XOD) inhibitor, on PSC were also examined.

RESULTS

DDC decreased SOD activity and increased lipid peroxidation products in PSC. DDC activated PSC, increasing the number of alpha-SMA positive cells, enhancing secretion of type I collagen and MMP, inhibiting PSC proliferation. Secretion of TGF-beta1, which is known to activate PSC, was increased by DDC treatment. These alterations were prevented by allopurinol.

CONCLUSION

These results suggest that free radicals generated by XOD might directly activate PSC.

Green tea polyphenol (-)-epigallocatechin-3-gallate inhibits ethanol-induced activation of pancreatic stellate cells

BACKGROUND

Activated pancreatic stellate cells (PSCs) play a central role in the pathogenesis of pancreatic fibrogenesis and inflammation. Ethanol, a major cause of chronic pancreatitis, directly induces PSC activation and oxidative stress. Inhibition of PSC activation or stimulation to PSC might be an effective therapeutic strategy for the prevention of pancreatic fibrosis, and (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea extracts, is a potent antioxidant of polyphenols. Therefore, we examined the mechanisms through which ethanol induces oxidative stress on PSCs and evaluated the effect of EGCG on activation and cell functions of ethanol-stimulated PSCs.

MATERIALS AND METHODS

The PSCs were isolated from the pancreas of male Wister rats with Nycodenz gradient methods and cells between passages one and four were used. Isolated PSCs were cultured with ethanol (50 mM) in the absence or presence of EGCG (5 microM or 25 microM).

RESULTS

The EGCG pre-treatment abolished ethanol-induced lipid peroxidation of the cell membrane, loss of total superoxide dismutase (SOD) activity and suppressed ethanol-induced gene expressions of Mn- and Cu/Zn-SOD. EGCG also suppressed ethanol-induced p38 mitogen-activated protein (MAP) kinase phosphorylation, alpha-smooth muscle actin production in PSCs and activated transforming growth factor-beta1 secretion into the medium. Furthermore, EGCG inhibited ethanol-induced type-I procollagen production and collagen secretion. In addition, EGCG inhibited transformation of freshly isolated cells to activated myofibroblast-like phenotype.

CONCLUSIONS

Our results suggest that green tea and polyphenols could prevent pancreatic fibrosis by inhibiting PSC activation through the antioxidative effect.

Camostat, an oral trypsin inhibitor, reduces pancreatic fibrosis induced by repeated administration of a superoxide dismutase inhibitor in rats

BACKGROUND AND AIM

An oral trypsin inhibitor, camostat (CM), has a beneficial effect on chronic pancreatitis, but its mechanism is not yet fully understood. Recently, pancreatic stellate cells (PSC) have been reported to play an essential role in pancreatic fibrosis. An experimental model of pancreatic fibrosis induced by a superoxide dismutase (SOD) inhibitor (diethyldithiocarbamate [DDC]) was developed in rats. Thus, the effect of an oral trypsin inhibitor on pancreatic fibrosis and PSC was investigated.

METHODS

Pancreatic fibrosis was induced in rats using DDC (DDC rats). DDC + CM rats were administered DDC, and subsequently were fed a diet containing CM. Immunohistochemistry of the pancreas was performed with monoclonal anti-alpha-smooth muscle actin (alpha-SMA) antibody and anti-desmin antibody.

RESULTS

The DDC rats showed a significant increase in alpha-SMA-positive cells or desmin-positive cells compared with control rats. These significant increases in the fibrotic area improved after treatment with CM. The level of prolyl hydroxylase in the pancreas, which significantly increased as a result of DDC, decreased after treatment with CM.

CONCLUSION

Camostat has a beneficial effect on pancreatic fibrosis induced by the administration of a SOD inhibitor, which inhibits the proliferation and activation of PSC.

Novel antioxidant ameliorates the fibrosis and inflammation of cerulein-induced chronic pancreatitis in a mouse model

BACKGROUND/AIM

Oxygen free radicals (OFRs) mediate an important step in the initiation of experimental acute pancreatitis and several clinical findings suggested the possible contribution of OFRs to the pathogenesis of pancreatic fibrosis. So far, there are no studies which reporting potential role of OFRs in development of chronic pancreatitis with the prevention with antioxidants. This study was aimed to establish the mice model of chronic fibrosing pancreatitis and to prove the involvement of OFRs in chronic pancreatitis with fibrosis.

METHODS

Repeated intraperitoneal cerulein injection was performed to induce chronic pancreatitis in mice. Histological changes in the pancreas were examined, and markers for oxidative stress were measured in the pancreatic tissue and serum of the mice. DA-9601, a phytochemical possessing anti-inflammatory and antioxidative action, was given together with cerulein to the mice.

RESULTS

Repeated intraperitoneal injection of cerulein provoked significant severity of chronic fibrosing pancreatitis after 5 weeks. After treatment of DA-9601, the extents of pancreatic fibrosis were statistically significantly decreased in accordance with lessened pancreatic inflammations. The NF-kappaB binding activities were increased in chronic pancreatitis, which were significantly attenuated after DA-9601 treatment. The levels of myeloperoxidase and iNOS activities were also significantly decreased in DA-9601-treated group compared to the pancreatitis only group. Cytoprotective proteins such as heat shock protein-70 (HSP) and metallothionein were significantly increased in the DA-9601-treated group. DA-9601 decreased the expressions of alpha-SMA and type I collagen in cultured pancreatic stellate cells.

CONCLUSIONS

Oxidative stress was principally involved in the pathogenesis of chronic pancreatitis with fibrosis.

Paraoxonase 1-192Q Allele is a Risk Factor for Idiopathic Chronic Pancreatitis

BACKGROUND

The cause of chronic pancreatitis (CP) remains unknown. However, oxidative stress might play a role since recent animal studies have demonstrated that oxygen-free radicals contribute to the pathogenesis of experimental pancreatitis. Human serum paraoxonase (PON1) is an antioxidant enzyme that protects against cellular damage from oxidative stress. Genetic variations resulting in variable activity rates of this enzyme, are of toxicological and physiological importance.

AIM

We investigated whether genetic polymorphisms of the PON1 gene modify the risk for CP.

MATERIALS AND METHODS

DNA samples were obtained from 236 adult CP patients of hereditary (n = 23), alcoholic (n = 137), or idiopathic (n = 76) origin. DNA from 113 healthy controls and from 93 alcoholic controls were analyzed for comparison. Patients and controls were all of Caucasian origin. Genetic polymorphisms (L55M and Q192R) in PON1 were determined by PCR, followed by restriction fragment length polymorphism analyses in all subjects.

RESULTS

The frequencies of the PON1-55 alleles did not differ between CP patients and healthy controls. However, the PON1-192Q allele was significantly more common in idiopathic CP patients (OR : 1.5, 95% CI 1.02, 2.5) compared with healthy controls.

CONCLUSIONS

These data suggest that the PON1-192Q allele, resulting in partly deficient antioxidant and detoxification activity of this enzyme, might be a risk factor for idiopathic CP in Caucasians.

Molecular mechanisms of alcoholic pancreatitis

Alcoholic pancreatitis is a major complication of alcohol abuse. Since only a minority of alcoholics develop pancreatitis, there has been a keen interest in identifying the factors that may confer individual susceptibility to the disease. Numerous possibilities have been evaluated including diet, drinking patterns and a range of inherited factors. However, at the present time, no susceptibility factor has been unequivocally identified. In contrast, considerable progress has been made with respect to the constant effects of alcohol on the pancreas. The molecular mechanisms of alcohol-induced pancreatic injury are being increasingly defined with an emphasis, in recent years, on the acinar cell itself as the principal site on ethanol-related damage. It has now been established that the acinar cell is capable of metabolizing alcohol and that the direct toxic effects of alcohol and/or its metabolites on acinar cells may predispose the gland to autodigestive injury in the presence of an appropriate triggering factor. A significant recent development relates to the characterization of pancreatic stellate cells, increasingly implicated in alcoholic pancreatic fibrosis. Here the current concepts regarding the mechanisms/pathways mediating alcohol-induced pancreatic injury are outlined.

Vitamin E attenuates biochemical and morphological features associated with development of chronic pancreatitis

The objective was to investigate the effects of vitamin E on collagen deposition induced by Cyclosporin A (CsA) administration in rats with caerulein (Cr) pancreatitis. CsA transforms the fully regenerative, self-limited form of Cr pancreatitis into a chroniclike disease in conjunction with increased transforming growth factor (TGF)-beta and myofibroblast proliferation. Vitamin E inhibits TGF-beta release in mesangial cells and reduces CsA cytotoxicity. Wistar rats received CsA daily (20 mg/kg), and CR pancreatitis was induced on days 1 and 8 (Cr + CsA group). In a separate group, vitamin E (600 mg.kg(-1).day(-1)) was administered starting 4 days before CsA. Three other groups received either vehicle, CsA, or Cr alone. Thiobarbituric acid-reactive substance (TBARS), 8-isoprostanes, and hyaluronic acid were measured in plasma obtained on the day the animals were killed (day 15). Pancreases were weighed and processed for light microscopy to assess connective tissue and myofibroblast number. Pancreatic homogenates were also assayed for collagen (hydroxyproline) and TBARS content. TBARS, 8-isoprostane, and TGF-beta were elevated in CsA and Cr + CsA rats. Vitamin E treatment greatly decreased these parameters. Vitamin E also decreased the fall in pancreatic weight observed in Cr + CsA pancreas. Pancreatic hydroxyproline and plasma hyaluronic acid were increased in Cr + CsA rats but were effectively reduced by vitamin E. Morphology showed improvement in fibrosis score and a decreased number of myofibroblasts in vitamin E-treated rats. Vitamin E reduces oxidative stress and collagen deposition during the development of experimental chronic pancreatitis. Adjuvant antioxidants may be of value in the treatment of chronic pancreatitis.

Mechanisms of pancreatic fibrosis

Pancreatic fibrosis, a characteristic histopathological feature of chronic pancreatitis, is no longer considered an epiphenomenon of chronic injury, but an active process that may be reversible in the early stages. The identification and characterization of pancreatic stellate cells (PSCs) in recent years has had a significant impact on research into pancreatic fibrogenesis. Accumulating evidence from both in vivo studies (using human pancreatic sections and experimental models of pancreatic fibrosis) and in vitro studies (using cultured pancreatic stellate cells) indicates a key role for activated PSCs in the fibrotic process. These cells are now known to be activated by ethanol and its metabolites and by several factors that are upregulated during pancreatic injury including growth factors, cytokines and oxidant stress. Based on this knowledge, potential antifibrotic strategies such as antioxidants and cytokine inhibition have been assessed in experimental models. Studies are also underway to characterise the signaling pathways/molecules responsible for mediating PSC activation, in order to identify potential therapeutic targets for the inhibition of PSC activation, thereby preventing or reversing the development of pancreatic fibrosis.

A mouse model of severe acute pancreatitis induced with caerulein and lipopolysaccharide

AIM: To establish a non-traumatic, easy to induce and reproducible mouse model of severe acute pancreatitis (SAP) induced with caerulein and lipopolyasccharide (LPS).

METHODS: Thirty-two healthy mature NIH female mice were selected and divided at random into four groups (each of 8 mice), i.e., the control group (NS group), the caerulein group (Cn group), the lipopolysaccharide group (LPS group), and the caerulein+LPS group (Cn + LPS group). Mice were injected intraperitoneally with caerulein only, or LPS only, and caerulein and LPS in combination. All the animals were then killed by neck dislocation three hours after the last intraperitoneal injection. The pancreas and exo-pancreatic organs were then carefully removed for microscopic examination. And the pancreatic acinus was further observed under transmission electron microscope (TEM). Pancreatic weight, serum amylase, serum nitric oxide (NO) concentration, superoxide dismutase (SOD) and malondialdehyde (MDA) concentration of the pancreas were assayed respectively.

RESULTS: (1) NS animals displayed normal pancreatic structure both in the exocrine and endocrine. In the LPS group, the pancreas was slightly edematous, with the infiltration of a few inflammatory cells and the necrosis of the adjacent fat tissues. All the animals of the Cn group showed distinct signs of a mild edematous pancreatitis characterized by interstitial edema, infiltration of neutrophil and mononuclear cells, but without obvious parenchyma necrosis and hemorrhage. In contrast, the Cn + LPS group showed more diffuse focal areas of nonviable pancreatic and hemorrhage as well as systemic organ dysfunction. According to Schmidt’s criteria, the pancreatic histologic score showed that there existed significant difference in the Cn + LPS group in the interstitial edema, inflammatory infiltration, parenchyma necrosis and parenchyma homorrhage in comparison with those of the Cn group, LPS group and NS group (P < 0.01 or P < 0.05). (2) The ultrasturcture of acinar cells was seriously damaged in the Cn + LPS group. Chromatin margination of nuclei was present, the number and volume of vacuoles greatly increased. Zymogen granules (ZGs) were greatly decreased in number and endoplasmic reticulum exhibited whorls. The swollen mitochondria appeared, the crista of which was decreased in number or disappeared. (3) Pancreatic weight and serum amylase levels in the Cn +LPS was significantly higher than those of the NS group and the LPS group respectively (P < 0.01 or P < 0.05). However, the pancreatic wet weight and serum amylase concentration showed no significant difference between the Cn + LPS group and the Cn group. (4) NO concentration in the Cn + LPS group was significantly higher than that of NS group, LPS group and Cn group(P < 0.05 or P < 0.01). 5) The SOD and MDA concentration of the pancreas in the Cn + LPS group were significantly higher than those of NS, LPS and Cn groups (P < 0.05 or P < 0.01).

CONCLUSION: The mouse model of severe acute pancreatitis could be induced with caerulein and LPS, which could be non-traumatic and easy to induce, reproducible with the same pathological characteristics as those of SAP in human, and could be used in the research on the mechanism of human SAP.