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

Circulating Biomarkers Involved in the Development of and Progression to Chronic Pancreatitis-A Literature Review

Chronic pancreatitis (CP) is the end-stage of continuous inflammation and fibrosis in the pancreas evolving from acute- to recurrent acute-, early, and, finally, end-stage CP. Currently, prevention is the only way to reduce disease burden. In this setting, early detection is of great importance. Due to the anatomy and risks associated with direct sampling from pancreatic tissue, most of our information on the human pancreas arises from circulating biomarkers thought to be involved in pancreatic pathophysiology or injury. The present review provides the status of circulating biomarkers involved in the development of and progression to CP.

Antioxidant Mitoquinone Alleviates Chronic Pancreatitis via Anti-Fibrotic and Antioxidant Effects

Background

Chronic pancreatitis (CP) is a long-term inflammatory disease of the pancreas that can be caused by various pathogenic factors. Oxidative stress (OS), which is associated with several pancreatic diseases, can induce pancreatic stellate cell (PSC) activation, leading to pancreatic fibrosis. Given the inefficacy of existing treatments for CP, in this study, our objective was to evaluate the therapeutic effect of the antioxidant, mitoquinone (MitoQ).

Methods

First, in vivo, we established a CP mouse model via the repeated injection of cerulein. Mice in the MitoQ group simultaneously received MitoQ daily. After 4 weeks of cerulein injection, pancreatic tissues from mice were evaluated by morphological changes and the expression of fibrosis markers. Further, OS in the collected pancreatic tissue samples was evaluated by determining the level of malondialdehyde (MDA) as well as the expression levels and activities of antioxidants. Furthermore, in vitro, the effect of MitoQ on human PSCs (hPSCs) was evaluated based on PSC activation markers and fibrotic phenotypes, and OS in these treated hPSCs was evaluated by measuring reactive oxygen species (ROS), MDA, and antioxidant levels.

Results

In vivo, MitoQ alleviated pancreatic fibrosis and inhibited OS in the cerulein-induced murine CP model. In vitro, it inhibited PSC activation as well as the subsequent development of the profibrogenic phenotypes by balancing out the levels of free radicals and the intracellular antioxidant system.

Conclusion

MitoQ is a potential candidate for CP treatment.

Mitochondria oxidative stress mediated nicotine-promoted activation of pancreatic stellate cells by regulating mitochondrial dynamics

Nicotine, one of the main ingredients of cigarettes, promotes activation of pancreatic stellate cells(PSCs) and exacerbates pancreatic fibrosis in previous studies. Here we focus on the inner relationship between mitochondrial oxidative stress and mitochondrial dynamics to explore the possible mechanism. Primary human PSCs were stimulated by nicotine. The effect of nicotine on oxidative stress and mitochondrial dynamics was analyzed by reactive oxygen species (ROS) assay, quantitative real-time PCR, and western blotting. Mitochondrial morphology was observed. Antioxidant and small interfering RNA transfection were applied to explore the interrelationship between oxidative stress and mitochondrial dynamics, as well as its effect on PSCs activation. Nicotine exposure significantly increased Intracellular and mitochondrial ROS of hPSCs and promoted mitochondrial fission by upregulating dynamin-related protein 1(DRP1). Knockdown Drp1 reversed mitochondrial fragmentation and hPSCs activation that promoted by nicotine, but fail to alleviate oxidative stress. A mitochondrial-targeted antioxidant could reverse all the above changes. Our finding suggests that mitochondria oxidative stress mediated nicotine-promoted activation of PSCs by inducing Drp1-mediated mitochondrial fission, provides a new perspective on the possible mechanism by which nicotine affects PSCs, and reveals a potential therapeutic strategy.

Pancreatic Stellate Cells: The Key Orchestrator of The Pancreatic Tumor Microenvironment

Pancreatic cancer is one of the most challenging adenocarcinomas due to its hostile molecular behavior and complex tumor microenvironment. It has been recently postulated that pancreatic stellate cells (PSCs), the resident lipid-storing cells of the pancreas, are important components of the tumor microenvironment as they can transdifferentiate into highly proliferative myofibroblasts in the context of tissue injury. Targeting tumor-stromal crosstalk in the tumor microenvironment has emerged as a promising therapeutic strategy against pancreatic cancer progression and metastasis. This chapter brings a broad view on the biological and pathological role of PSCs in the pancreas, activated stellate cells in the onset of tissue fibrosis, and tumor progression with particular emphasis on the bidirectional interactions between tumor cells and PSCs. Further, potential therapeutic regimens targeting activated PSCs in the pre-clinical and clinical trials are discussed.

Pancreatic stellate cell: Pandora's box for pancreatic disease biology

Pancreatic stellate cells (PSCs) were identified in the early 1980s, but received much attention after 1998 when the methods to isolate and culture them from murine and human sources were developed. PSCs contribute to a small proportion of all pancreatic cells under physiological condition, but are essential for maintaining the normal pancreatic architecture. Quiescent PSCs are characterized by the presence of vitamin A laden lipid droplets. Upon PSC activation, these perinuclear lipid droplets disappear from the cytosol, attain a myofibroblast like phenotype and expresses the activation marker, alpha smooth muscle actin. PSCs maintain their activated phenotype via an autocrine loop involving different cytokines and contribute to progressive fibrosis in chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Several pathways (e.g., JAK-STAT, Smad, Wnt signaling, Hedgehog etc.), transcription factors and miRNAs have been implicated in the inflammatory and profibrogenic function of PSCs. The role of PSCs goes much beyond fibrosis/desmoplasia in PDAC. It is now shown that PSCs are involved in significant crosstalk between the pancreatic cancer cells and the cancer stroma. These interactions result in tumour progression, metastasis, tumour hypoxia, immune evasion and drug resistance. This is the rationale for therapeutic preclinical and clinical trials that have targeted PSCs and the cancer stroma.

Role of methionine containing antioxidant combination in the management of pain in chronic pancreatitis: a systematic review and meta-analysis

BACKGROUND

Pain in CP results from inflammation and neuroimmune alterations that are associated with oxidative stress, among other mechanisms. This is marked by depletion of antioxidant defenses including methionine, which is a donor of methyl moieties that maintains the acinar transsulfuration pathway. We performed a systematic review and meta-analysis of trials evaluating methionine-containing antioxidants in CP.

PATIENT AND METHODS

Literature search was conducted in Medline/Pubmed, EMBASE, and Cochrane databases. Systematic review and meta-analysis was performed per PRISMA guidelines. Main study outcome was pain relief. GRADE system was used for quality assessment. Heterogeneity was assessed by the Q and I(2) measures; publication bias by Egger's test. Random-effect model (DerSimonian and Laird) was used if there was heterogeneity.

RESULTS

Eight studies (n = 411) were identified that used methionine-containing antioxidants. The study duration ranged from 10 wks to 12 months. All studies used methionine, organic selenium, ascorbate, beta-carotene and alpha-tocoferol. Four studies (including two RCTs) that reported change in pain scores were metaanalyzed. Though overall effect [standardized difference in means (95% CI)] on pain score reduction was -0.95 (-1.738 to -0.160) (z = -2.36; p = 0.018), the significance was lost when the two RCTs were meta-analyzed. RCTs that reported the number of pain free patients had a statistically significant overall effect of -3.204 (p = 0.001). Though more patients on methionine containing antioxidants had adverse events, majority of them were mild.

CONCLUSION

Methionine containing antioxidants appear to result in pain reduction in a significant proportion of CP patients. Further randomized controlled trials with homogeneous outcome measures are needed.

Allopurinol reverses liver damage induced by chronic carbon tetrachloride treatment by decreasing oxidative stress, TGF-β production and NF-κB nuclear translocation

Allopurinol is an inhibitor of xanthine oxidase. The aim of this work was to evaluate the efficacy of allopurinol to reverse the experimental cirrhosis induced by CCl4. Rats received CCl4 for 8 weeks, and immediately after allopurinol was administered for 4 weeks more. Allopurinol reversed all markers of liver damage and oxidative stress to normal values, restoring the metabolic capacity of the liver. Chronic injury by CCl4 induced significant overexpression of profibrogenic cytokine TGF-β, while allopurinol decreased this production and consequently decreased the collagen content. Moreover, allopurinol is capable of partially inhibiting NF-κB. These findings suggest that allopurinol is capable of reversing the cirrhosis induced by CCl4, modulating oxidative stress, TGF-β expression and NF-κB nuclear translocation.

Intake patterns of food nutrients and other substances associated with chronic pancreatitis

BACKGROUND/OBJECTIVES

While alcohol is considered the most common aetiological factor for chronic pancreatitis, the intake of various nutrient and other substances is thought to act as cofactors in the pathogenesis of the disease due to modulation of oxidative stress. This study examined incident cases of acute pancreatitis to determine the dietary and other intakes that characterize those harbouring underlying chronic pancreatitis.

METHODS

Cases of acute pancreatitis presenting to a single institution were prospectively recruited (n = 153). The presence of chronic pancreatitis was defined by a composite of clinical, biochemical and radiological criteria. Information was obtained on the intake of dietary macro- and micronutrients, coffee, tobacco and alcohol in the period just prior to the acute exacerbation. Univariate and multivariate analyses of association were undertaken. Principal components analysis (PCA) was employed to elicit patterns of intake.

RESULTS

After adjustment for key demographic variables, no individual nutrient or other substance showed a significant association with chronic pancreatitis. However, following PCA there emerged a significant positive association with a so-called "stimulant" intake pattern and a negative association with a so-called "nutritive" pattern.

CONCLUSIONS

Preceding an acute exacerbation, patients with underlying chronic pancreatitis are more likely to substitute food-based intake for combinations of other substances, such as tobacco and coffee. This finding may have application in the clinical setting as part of a chronic disease management protocol.

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.

Involvement of nuclear factor kappa B in high-fat diet-related pancreatic fibrosis in rats

Background/Aims

High-fat diets contribute to pancreatic fibrogenesis, but the pathogenesis remains unclear. This study investigated the role of nuclear factor kappa B (NF-κB) in high-fat diet-induced pancreatic fibrosis in rats.

Methods

Male Wistar rats were fed a high-fat diet or standard normal chow for 20 weeks. Pancreatic fibrosis was determined by Sirius red staining. Immunohistochemical staining, reverse transcription-polymerase chain reaction and Western blotting were used to identify NF-κB-associated genes or protein expressions.

Results

Inflammation, fat deposition, pancreatic stellate cell activation and fibrosis were observed in the pancreases of the high-fat diet group. NF-κB subunit p65 (NF-κB/p65) expression was localized to the nucleus, and intercellular adhesion molecule 1 (ICAM-1) was over-expressed. Pancreatic gene expression levels of NF-κB/p65, ICAM-1 and tumor necrosis factor α were all elevated significantly in rats fed a high-fat diet compared with control rats. Western blotting also revealed significantly increased levels of ICAM-1 and nuclear NF-κB/p65 in rats fed high-fat diets comparison with control rats.

Conclusions

NF-κB is involved in high-fat diet-related pancreatic fibrosis.

Antioxidants and chronic pancreatitis: theory of oxidative stress and trials of antioxidant therapy

Chronic pancreatitis (CP) is an inflammatory disease characterized by the progressive destruction of pancreatic tissue and resulting in pancreatic exocrine and endocrine insufficiency. Increased oxidative stress has been implicated as a potential mechanism in its etiology and pathology. A number of studies have demonstrated that CP patients have a compromised antioxidant status, which may be a contributing factor to the enhanced oxidative state associated with the disease. Nutrition is an essential consideration in the treatment of CP, especially since diet is a source of several antioxidants and cofactors required for the production of cellular antioxidant enzymes. Many CP patients have an inadequate intake of macro and micronutrients because of abdominal pain and discomfort, which often increase postprandially and discourage eating. Exocrine insufficiency leads to further complications by preventing adequate digestion and absorption of ingested food, thus causing even greater deficiencies and impairment of antioxidant status. The aims of this article are to review the oxidative stress model of CP and to examine the evidence for nutrition, and, particularly, antioxidants, in the treatment of CP.

L-cysteine administration attenuates pancreatic fibrosis induced by TNBS in rats by inhibiting the activation of pancreatic stellate cell

BACKGROUND AND AIMS

Recent studies have shown that activated pancreatic stellate cells (PSCs) play a major role in pancreatic fibrogenesis. We aimed to study the effect of L-cysteine administration on fibrosis in chronic pancreatitis (CP) induced by trinitrobenzene sulfonic acid (TNBS) in rats and on the function of cultured PSCs.

METHODS

CP was induced by TNBS infusion into rat pancreatic ducts. L-cysteine was administrated for the duration of the experiment. Histological analysis and the contents of hydroxyproline were used to evaluate pancreatic damage and fibrosis. Immunohistochemical analysis of α-SMA in the pancreas was performed to detect the activation of PSCs in vivo. The collagen deposition related proteins and cytokines were determined by western blot analysis. DNA synthesis of cultured PSCs was evaluated by BrdU incorporation. We also evaluated the effect of L-cysteine on the cell cycle and cell activation by flow cytometry and immunocytochemistry. The expression of PDGFRβ, TGFβRII, collagen 1α1 and α-SMA of PSCs treated with different concentrations of L-cysteine was determined by western blot. Parameters of oxidant stress were evaluated in vitro and in vivo. Nrf2, NQO1, HO-1, IL-1β expression were evaluated in pancreas tissues by qRT-PCR.

RESULTS

The inhibition of pancreatic fibrosis by L-cysteine was confirmed by histological observation and hydroxyproline assay. α-SMA, TIMP1, IL-1β and TGF-β1 production decreased compared with the untreated group along with an increase in MMP2 production. L-cysteine suppressed the proliferation and extracellular matrix production of PSCs through down-regulating of PDGFRβ and TGFβRII. Concentrations of MDA+4-HNE were decreased by L-cysteine administration along with an increase in GSH levels both in tissues and cells. In addition, L-cysteine increased the mRNA expression of Nrf2, NQO1 and HO-1 and reduced the expression of IL-1β in L-cysteine treated group when compared with control group.

CONCLUSION

L-cysteine treatment attenuated pancreatic fibrosis in chronic pancreatitis in rats.

Uric acid and HMGB1 are involved in the induction of autoantibodies elicited in mice infected with mouse hepatitis virus A59

We have shown that mice infected with mouse hepatitis virus A59 develop autoantibodies (autoAb) to liver and kidney fumarylacetoacetate hydrolase (FAH). Because it has been proposed that the immune system is stimulated by alarm signals called damage-associated molecular patterns or alarmins, we investigated the participation of uric acid and high-mobility group box protein 1 (HMGB1) in the autoimmune response elicited by mouse hepatitis virus (MHV). Mice subjected to MHV infection had increased plasmatic uric acid concentration that significantly decreased after 20 days of daily treatment with allopurinol and, simultaneously, autoAb to FAH were undetected. Furthermore, this autoAb disappeared after 30 days of treatment with ethyl pyruvate, along with a substantial reduction in serum HMGB1 concentration. Both results indicated a remarkable relationship between the autoimmune process induced by the virus and uric acid and HMGB1 liberation. Unexpectedly, it was found that allopurinol and ethyl pyruvate inhibited the release of both uric acid and HMGB1. Because HMGB1 is activated through binding to interleukin 1β, and that this cytokine is produced by the NLRP3 inflammasome that could be stimulated by uric acid, we propose that both alarmins could be acting in concert with the induction of the autoAb to FAH in MHV-infected mice.

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.

Protective effects of allopurinol against acute liver damage and cirrhosis induced by carbon tetrachloride: modulation of NF-κB, cytokine production and oxidative stress

BACKGROUND

The aim of this work was to evaluate the hepatoprotective ability of allopurinol to prevent the liver injury induced by carbon tetrachloride (CCl(4)).

METHODS

Acute liver damage was induced with CCl(4) (4g/kg, by gavage); allopurinol (50mg/kg, by gavage) was given 1h before and 1h after CCl(4) intoxication and two daily doses for the previous three days. Cirrhosis was established by CCl(4) administration (0.4g/kg, i. p. three times a week, eight weeks); allopurinol was administered (100mg/kg, by gavage, daily) during the long-term of CCl(4) treatment. Alanine aminotransferase (ALT), γ-glutamyl transpeptidase (γ-GTP), xanthine oxidase (XO), lipid peroxidation, reduced and oxidized glutathione (GSH, GSSG, respectively), hydroxyproline and histopathologycal analysis were performed. Nuclear factor-κB (NF-κB), pro-inflammatory and anti-inflammatory cytokines, transforming growth factor-β (TGF-β) and metalloproteinase-13 (MMP-13) were analyzed by Western blots.

RESULTS

Acute injury increased ALT and γ-GTP activities, additionally enhanced NF-κB nuclear translocation and cytokines production such as tumor necrosis factor-α, interleukine-1β, and interleukine-6. Allopurinol partially prevented these effects, while increased interleukine-10. Acute and chronic CCl(4) treatments altered the levels of XO activity, lipid peroxidation, and GSH/GSSG ratio, while these remained within normal range with allopurinol administration. Necrosis, fibrosis and TGF-β production induced in chronic injury were partially prevented by allopurinol, interestingly, this drug induced MMP-13 activity.

CONCLUSIONS

Allopurinol possesses antioxidant, anti-inflammatory and antifibrotic properties, probably by its capacity to reduce NF-κB nuclear translocation and TGF-β expression, as well as to induce MMP-13. General significance Allopurinol might be effective treatment of liver diseases.

Comparison of antioxidative and antifibrotic effects of α-tocopherol with those of tocotrienol-rich fraction in a rat model of chronic pancreatitis

OBJECTIVES

The α-tocopherol and tocotrienol-rich fraction (TRF) are considered effective antioxidants. This study aimed to compare the antioxidative and antifibrotic effects of α-tocopherol and TFR in dibutylin dichloride (DBTC)-induced chronic pancreatitis (CP) rats.

METHODS

Oral administration of α-tocopherol and TFR (both 800 mg/kg per day) started the next day after DBTC (8 mg/kg) infusion into the tail vein for 4 weeks. Histological examination, Sirius red staining, and measurement of the contents of hydroxyproline and malondialdehyde of the pancreas were performed to evaluate pancreatic damage and fibrosis. Immunohistochemical analysis of α-smooth muscle actin and real-time reverse transcription polymerase chain reaction for transforming growth factor-β1 (TGF-β1) and collagen-α1(I) were performed to evaluate the activation of pancreatic stellate cells and the mRNA levels of fibrosis-related genes, respectively.

RESULTS

Both α-tocopherol and TRF reduced oxidative stress, ameliorated inflammation and fibrosis, and down-regulated the mRNA expression of TGF-β1 and collagen-α1(I) in DBTC-induced CP. The TRF was superior to α-tocopherol in alleviating inflammation and fibrosis and down-regulating TGF-β1 mRNA expression.

CONCLUSIONS

Oral administration of α-tocopherol and TRF improves pancreatic inflammation and fibrosis in DBTC-induced CP rats, with TRF being more effective than α-tocopherol. Therefore, TRF may be a novel option for alleviating inflammation and, particularly, the fibrotic process in CP.

Chronic pancreatitis: potential future interventions

Chronic pancreatitis is a common disorder of which the underlying pathogenic mechanisms still are incompletely understood. In the last decade, increasing evidence has shown that activated pancreatic stellate cells play a key role in the fibrosis development associated with chronic pancreatitis as well as pancreatic cancer. During pancreatic injury or inflammation, quiescent stellate cells undergo a phenotypic transformation, characterized by smooth muscle alpha-actin expression and increased synthesis of extracellular matrix proteins. Hitherto, specific therapies to prevent or reverse pancreatic fibrosis are unavailable. This review addresses current insights into pathological mechanisms underlying chronic pancreatitis and their applicability as concerns the development of potential future therapeutic approaches.

Allopurinol in dermatology

Off-label use is common in dermatology, and is inevitable for rare cutaneous diseases such as perforating dermatosis. Allopurinol is traditionally considered to be a drug for hyperuricemia only, but the recent demonstration of its efficacy in congestive heart failure has spurred renewed interest in its application in other clinical specialties. In dermatology, allopurinol is best known for its severe cutaneous adverse reactions. Recent genomic studies conducted in Taiwan have discovered useful HLA markers for determining the susceptibility of Stevens-Johnson syndrome and toxic epidermal necrolysis associated with allopurinol. Allopurinol has also been used in a number of dermatologic disorders including acquired reactive perforating collagenosis, sarcoidosis, psoriasis and granulomas caused by methacrylate microspheres, silicon and tattoos. Allopurinol may express its therapeutic effects via its antioxidation or anti-inflammatory properties, or its ability to improve vascular function.

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.

High-dose naproxen aggravates pancreatic fibrosis in a rat model of chronic pancreatitis

OBJECTIVES

: Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely prescribed for the treatment of pain in chronic pancreatitis (CP). This study aimed to investigate the effect of NSAIDs on the inflammation and fibrosis progression in trinitrobenzene sulfonic acid-induced CP rats.

METHODS

Chronic pancreatitis was induced by trinitrobenzene sulfonic acid infusion into rat pancreatic ducts. Naproxen treatment (20 and 40 mg/kg per os [PO] and intraperitoneally) started 2 weeks after the induction of CP for 3 weeks. Histological analysis of the pancreas, Van Gieson staining, and contents of hydroxyproline were used to evaluate pancreatic damage and fibrosis. Furthermore, the effect of naproxen on nociceptive reflective behaviors and serum tumor necrosis factor alpha concentration were studied, and immunohistochemical analysis of alpha-smooth muscle actin in the pancreas was performed.

RESULTS

Pancreatic collagen content and alpha-smooth muscle actin expression were higher in the CP group treated with high-dose (40 mg/kg PO) naproxen (P < 0.05). High-dose naproxen administered orally aggravated pancreatic fibrosis and inflammation (P < 0.05). Instead of playing an analgesic role, high-dose naproxen decreased the thermal withdrawal latencies in CP rats (P < 0.05).

CONCLUSIONS

High-dose naproxen treatment (40 mg/kg PO) aggravated pancreatic fibrosis in CP rats and played an algogenic role that suggests the potential risk of long-term use of NSAIDs as analgesic in clinical practice with CP.

Role of oxidative stress in pancreatic inflammation

Reactive oxygen and reactive nitrogen species (ROS/RNS) have been implicated in the pathogenesis of acute and chronic pancreatitis. Clinical and basic science studies have indicated that ROS/RNS formation processes are intimately linked to the development of the inflammatory disorders. The detrimental effects of highly reactive ROS/RNS are mediated by their direct actions on biomolecules (lipids, proteins, and nucleic acids) and activation of proinflammatory signal cascades, which subsequently lead to activation of immune responses. The present article summarizes the possible sources of ROS/RNS formation and the detailed signaling cascades implicated in the pathogenesis of pancreatic inflammation, as observed in acute and chronic pancreatitis. A therapeutic ROS/RNS-scavenging strategy has been advocated for decades; however, clinical studies examining such approaches have been inconsistent in their results. Emerging evidence indicates that pancreatitis-inducing ROS/RNS generation may be attenuated by targeting ROS/RNS-generating enzymes and upstream mediators.

Chronic pancreatitis

PURPOSE OF REVIEW

As in previous reviews in this journal, this review is focused on the most important new observations in chronic pancreatitis made in the last year.

RECENT FINDINGS

Important observations included the search for biomarkers and alternative methods for the detection of early chronic pancreatitis; stellate cell activation and their role in fibrogenesis; the natural history of chronic pancreatitis; reports outlining the complexity in diagnosis of autoimmune pancreatitis; emerging roles of endoscopic ultrasound and magnetic resonance cholangiopancreatography in chronic pancreatitis diagnosis; a better understanding of neurobiology of chronic pancreatitis pain; and the potential role of surgery as first-line therapy in advanced chronic pancreatitis.

SUMMARY

In 2007, major advances were made in our understanding of central processing in chronic pancreatitis pain. New techniques are being utilized in search of a better means to diagnose early chronic pancreatitis. Important prospective studies are emerging, which compare endoscopic and surgical interventions. Furthermore, the complexities of diagnosing autoimmune pancreatitis are being recognized. Overall, the future is promising as advances in genomic and proteomic techniques are applied to improve our understanding of chronic pancreatitis.