Genetic predisposition to alcoholic chronic pancreatitis

The mechanisms leading to alcoholic chronic pancreatitis in humans have remained elusive. Numerous questions surround the apparent random nature of the disease in which 1 person is hit with alcoholic chronic pancreatitis while the next is spared. Why do fewer than 10% of chronic, heavy alcohol users ever develop pancreatitis, while others develop alcoholic liver disease, neuropathy, or other alcohol-associated problems? Why do laboratory animals, fed large amounts of alcohol for prolonged periods of time, fail to develop typical chronic pancreatitis? Why are heavy alcohol users from a black African background more likely to develop pancreatic diseases than Caucasians, whereas the opposite is true for the development of liver disease? The answers underlying these questions appear to reflect the differences in underlying genetic susceptibility, environmental exposure, and the interaction between these factors. Thus, even cases of "typical" alcoholic chronic pancreatitis or other forms of pancreatitis appear to be complex diseases. Recently, several genetic mutations have been identified that increase the susceptibility to pancreatitis. However, the major common gene mutations in CFTR, PRSS1, and SPINK1 only slightly increase the risk of alcoholic chronic pancreatitis. New genetic, environmental, and triggering factors must be considered to gain further insight into the mechanisms leading to alcoholic chronic pancreatitis so that strategies for treatment and prevention can be developed.

Role of alcohol metabolism in alcoholic pancreatitis

Metabolism of ethanol by acinar and other pancreatic cells and the consequent generation of toxic metabolites are postulated to play an important role in the development of alcohol-related acute and chronic pancreatic injury. Studies using cultured pancreatic acinar cells and isolated pancreatic acini have established that (i) the pancreas can metabolize ethanol via the oxidative pathway involving the enzymes alcohol dehydrogenase (ADH) and possibly cytochrome P4502E1 (although the role of the latter remains to be fully delineated) as well as the nonoxidative pathway [involving fatty acid ethyl ester (FAEE) synthases] and (ii) the oxidative pathway (which generates acetaldehyde) is quantitatively greater than the nonoxidative pathway, which yields FAEEs. Most recently, pancreatic stellate cells (PSCs) (implicated in pancreatic fibrogenesis) have been reported to exhibit ADH activity, suggesting that the capacity of the pancreas to metabolize ethanol may reside not only in parenchymal (acinar) cells but also in nonparenchymal cells. Polymorphisms/mutations of ethanol metabolizing enzymes have been examined to determine whether they may confer individual susceptibility to alcoholic pancreatitis. However, no association has been demonstrated between ADH and CYP2E1 polymorphisms and the predisposition to alcoholic pancreatitis. Other candidate factors that remain to be studied include polymorphisms of FAEE synthetic enzymes and proteins relevant to antioxidant pathways in the cell. Injury to the pancreas due to its capacity to metabolize ethanol may be mediated by direct effects of both acetaldehyde and FAEEs and by alterations induced within the cells during ethanol metabolism, such as changes in the intracellular redox state and the generation of oxidant stress.

Animal model of alcoholic pancreatitis: role of viral infections

Pancreatitis is clearly associated with alcohol abuse, but only a relatively small percentage of people who abuse alcohol develops obvious pancreatitis. These observations have led to the concept that the development of alcoholic pancreatitis requires cofactors. Although diet and smoking have been studied, a clear cofactor has not been identified. The study results presented in this paper were obtained to determine whether viral infection of the pancreas would be a cofactor for alcoholic pancreatitis similar to the role of hepatitis virus infections in the development of alcoholic liver disease. To test this hypothesis, mice were fed ethanol with a liquid diet protocol and infected with coxsackievirus B3 (CVB3). It was found that consumption of alcohol alone did not result in pancreatitis as determined by serum levels of amylase or histologic changes in the pancreas. Two strains of CVB3 that are tropic for the pancreas were used; a virulent and an avirulent strain. Infection of alcohol-fed animals with the virulent CVB3 strain 28 resulted in a more severe pancreatitis than the pancreatitis noted in control animals. Alcohol-fed mice infected with the avirulent strain (GA) showed severe pancreatitis, whereas the infection of control mice did not result in obvious pathologic effects in the pancreas. This model allows mechanistic studies to define the role of viral infection as a cofactor for alcoholic pancreatitis.

Pathophysiology of alcohol-induced pancreatic injury

The evidence that ethanol abuse can lead to pancreatitis is overwhelming, but the mechanism(s) by which ethanol causes pancreatic injury and pancreatitis are not known. Many studies have focused on short-term effects of ethanol administration on exocrine pancreatic function, but the results reported have been variable and no clear picture has emerged. Attempts to induce pancreatitis by long-term ethanol administration have, for the most part, failed. We evaluated the effects of ethanol administration on pancreatic secretion of digestive enzymes. These studies indicate that administration of ethanol results in a transient increase in pancreatic amylase output and plasma cholecystokinin (CCK) levels. This phenomenon is mediated by a trypsin-sensitive CCK-releasing factor that is present within the duodenal lumen. These observations lead us to speculate that repeated CCK-mediated, ethanol-induced stimulation of pancreatic digestive enzyme secretion may play a role in the events that link ethanol abuse to the development of pancreatic injury.

Mutations of the CFTR gene in pancreatic disease

INTRODUCTION

An association has been found between CFTR gene mutations and chronic pancreatitis; however, there is a lack of information about the frequency of CFTR gene mutations in acute pancreatitis and in pancreatic cancer.

AIM

To prospectively evaluate the prevalence of CFTR gene mutations in acute pancreatitis, chronic pancreatitis, and pancreatic cancer.

METHODOLOGY

Ninety-eight consecutive patients were studied and divided into 3 groups: 34 patients with acute pancreatitis, 46 patients with chronic pancreatitis, and 18 patients with pancreatic cancer. The mutation analysis of the CFTR gene was carried out using diagnostic commercial kits for the simultaneous detection of 29 mutations and Tn polymorphism.

RESULTS

Among the 98 patients studied, 12 (12.2%) had CFTR gene mutations: 2 of the 34 patients (5.9%) with acute pancreatitis, 9 of the 46 (19.6%) with chronic pancreatitis, and 1 of the 18 (5.6%) with pancreatic cancer. All the mutations were found in heterozygosis (2 DeltaF508, 1 W1282X, and 9 T5 allele).

CONCLUSION

Our prospective study adds further information about the frequency of CFTR mutations in patients with a single episode of acute pancreatitis. Furthermore, our results suggest an association of CFTR gene mutations with chronic alcoholic pancreatitis and emphasize the need for a multicenter study, possibly multinational, to conclusively establish the role of CFTR mutations as a genetic susceptibility factor for this disease.

Stellate cell activation in alcoholic pancreatitis

The pathogenesis of pancreatic fibrosis, a characteristic feature of alcohol-induced chronic pancreatitis, has received increasing attention over the past few years, largely due to the identification and characterization of stellate cells in the pancreas. These cells are morphologically similar to hepatic stellate cells, the principal effector cells in liver fibrosis. The role of pancreatic stellate cells (PSCs) in alcoholic pancreatic fibrosis has been studied using 2 approaches: (i) in vivo studies using pancreatic tissue from patients with alcohol-induced chronic pancreatitis and from animal models of experimental pancreatitis and (ii) in vitro studies using cultured PSCs. These studies indicate that PSCs are activated early in the course of pancreatic injury and are the predominant source of collagen in the fibrotic pancreas. Several factors that may be responsible for mediating PSC activation during chronic alcohol exposure have also been identified. From the findings to date, it may be speculated that the pathogenesis of alcoholic pancreatic fibrosis may involve 2 pathways: (i) a necroinflammatory pathway involving cytokine release and PSC activation and (ii) a nonnecroinflammatory pathway involving direct activation of PSCs by ethanol via its metabolism to acetaldehyde and the generation of oxidant stress.

Role of PGE2 in the development of pancreatic injury induced by chronic alcohol feeding in rats

BACKGROUND

Eicosanoids are known to modulate inflammation. Moreover, some studies report that endogenous prostaglandin E(2) (PGE(2)) protects the pancreas against injury. Therefore, we investigated its role in a rat model of chronic alcohol consumption.

METHODS

Rats were fed with 20% ethanol and a corn oil-supplemented diet using the interrupted alcohol feeding regimen (EI). Controls received water instead of ethanol (WI) or uninterruptedly ethanol (EU). After 13 mo, pancreas tissue was investigated morphologically, immunohistochemically and biochemically.

RESULTS

Pancreatic tissue was more severely injured in EI than in WI and EU (p < 0.05). Fibrogenesis (alpha-smooth muscle actin-positive cells, collagen types I and III) was increased in EI compared to WI (p < 0.05). In EI, mast cell numbers were increased, compared to WI, but decreased, compared to EU (p < 0.05). EI showed decreased PGE(2) and malondialdehyde contents compared to EU (p < 0.05) and decreased glutathione concentrations compared to WI (p < 0.05). PGE(2) content and fibrogenesis were inversely correlated in EU. The same correlation was detectable as a trend in all alcohol-fed rats.

CONCLUSION

The decrease in PGE(2) together with the increase in tissue damage and the inverse correlation between PGE(2) and fibrogenesis led us to suggest that endogenous PGE(2) plays a protective role in alcohol-induced injury in the pancreas.

Rho kinase inhibitors block activation of pancreatic stellate cells

1. In response to pancreatic injury and in cell culture, pancreatic stellate cells (PSCs) are transformed ('activated') into highly proliferative myofibroblast-like cells, which express alpha-smooth muscle actin (alpha-SMA), and produce type I collagen and other extracellular matrix components. There is accumulating evidence that activated PSCs play important roles in pancreatic fibrosis and inflammation. 2. The small GTP-binding protein Rho has emerged as an important regulator of the actin cytoskeleton and cell morphology through the downstream effector Rho kinase (ROCK). But, the roles of Rho-ROCK pathway in PSCs are unknown. Here, we examined the effects of (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide (Y-27632) and HA-1077 (fasudil), specific inhibitors of ROCK, on the activation of PSCs. 3. PSCs were isolated from the pancreas of male Wistar rats after perfusion with collagenase P. The actin cytoskeleton was analyzed by phalloidin staining. Expression of RhoA and ROCK was examined by immunostaining and Western blotting. Effects of Y-27632 and HA-1077 on alpha-SMA expression, platelet-derived growth factor-induced proliferation and chemotaxis, and collagen production were assessed. 4. Culture-activated PSCs developed a well-spread cell shape, with extended stress fiber formation. PSCs expressed RhoA, ROCK-1, and ROCK-2. 5. Y-27632 caused disassembly of stress fibers. Y-27632 and HA-1077 inhibited alpha-SMA expression, proliferation, chemotaxis, and type I collagen production in culture-activated PSCs. 6. In addition, Y-27632 and HA-1077 inhibited spontaneous activation of freshly isolated PSCs in culture on plastic. 7. These findings suggest a role of Rho-ROCK pathway in the activation process of PSCs by regulating the actin cytoskeleton, and a potential application of Rho-ROCK pathway inhibitors for the treatment of pancreatic inflammation and fibrosis.

Candesartan, an angiotensin II receptor antagonist, suppresses pancreatic inflammation and fibrosis in rats

Angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists attenuate fibrosis in the kidney, heart, and liver by suppressing transforming growth factor-beta1 mRNA and decreasing production of extracellular matrix proteins. We recently demonstrated that lisinopril, an angiotensin-converting enzyme inhibitor, alleviates pancreatic inflammation and fibrosis in male Wistar Bonn/Kobori rats. The involvement of angiotensin II receptor and its receptor interaction in the pathogenesis of spontaneous chronic pancreatitis was assessed in this model. Candesartan, an angiotensin II receptor antagonist, was administered in drinking water (10.5, 42, or 125 mg/l) to 10-week-old male WBN/Kob rats for 10 weeks and inflammatory parameters, fibrosis, and gene expression of renin-angiotensin system components and transforming growth factor-beta1 were assessed in the pancreas. Immunostaining for alpha-smooth muscle actin was also performed. Candesartan significantly suppressed decrease in pancreatic weight and increases in pancreatic myeloperoxidase activity, hydroxyproline content, ratio of fibrous tissue, histologic scores, and ratio of alpha-smooth muscle actin-positive cells (activated pancreatic stellate cells) at 20 weeks. The high dose enhanced the expression of angiotensinogen and angiotensin II receptor type 2 mRNA and suppressed the overexpression of transforming growth factor-beta1 mRNA. The conclusion is that candesartan alleviates chronic pancreatitis and fibrosis by suppressing the overexpression of transforming growth factor-beta1, resulting in prevention of activation of pancreatic stellate cells in male WBN/Kob rats. We propose that angiotensin II receptor type 1 antagonists may be useful for the treatment of chronic pancreatitis involving angiotensin II interaction with its receptor.

Activin A is an autocrine activator of rat pancreatic stellate cells: potential therapeutic role of follistatin for pancreatic fibrosis

BACKGROUND AND AIM

The present study was conducted to examine the effect of activin A on activation of rat pancreatic stellate cells (PSCs).

METHODS

PSCs were prepared from rat pancreas using collagenase digestion and centrifugation with Nycodenz gradient. Activation of PSCs was examined by determining smooth muscle actin expression with western blotting. The presence of activin A receptors in PSCs was investigated by reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunocytochemistry. Expression of activin A and transforming growth factor beta (TGF-beta) mRNA was examined by RT-PCR. Activin A and TGF-beta peptide concentrations were examined with ELISA. Existence of activin A peptide in PSCs was investigated by immunocytochemistry. Collagen secretion was determined by Sirius red dye binding.

RESULTS

Activin A receptors I and IIa were present in PSCs. PSCs expressed activin A mRNA and secreted activin A. Activin A enhanced PSC activation and collagen secretion in a dose dependent manner. TGF-beta and activin A increased each other's secretion and mRNA expression of PSCs. Follistatin decreased TGF-beta mRNA expression and TGF-beta secretion of PSCs, and inhibited both PSC activation and collagen secretion.

CONCLUSION

Activin A is an autocrine activator of PSCs. Follistatin can inhibit PSC activation and collagen secretion by blocking autocrined activin A and decreasing TGF-beta expression and secretion of PSCs.

Chronic intragastric alcohol exposure causes hypoxia and oxidative stress in the rat pancreas

The effect of chronic enteral ethanol on pancreatic hypoxia was investigated using the hypoxia marker, pimonidazole. Male Wistar rats were fed an ethanol-containing diet for 3 weeks using an enteral model shown to cause pancreatic damage; pimonidazole (120 mg/kg i.v.) was injected 1h before sacrifice. Pimonidazole and 4-hydroxynonenal (an index of lipid peroxidation) adducts were detected immunochemically. Breathing air with low oxygen content (8% O(2)) for 1h increased pimonidazole adduct accumulation approximately 2-fold in pancreata of nai;ve rats, confirming that this technique will detect increases in hypoxia in pancreata. Pancreata of rats fed ethanol began to show signs of damage after 3 weeks. Ethanol feeding also significantly increased pimonidazole adducts in pancreas approximately 2-fold (1 or 3 weeks of ethanol produced similar values). Concomitant with increasing hypoxia in the pancreas, alcohol also caused a significant increase in 4-hydroxynonenal adducts, indicative of increased oxidative stress. These results indicate that chronic ethanol causes hypoxia at the cellular level in the pancreas in vivo; further, the data support the hypothesis that hypoxia is involved in mechanisms of chronic alcoholic pancreatitis.

Effects of ethanol and folic acid consumption during pregnancy and lactation on basal enzymatic secretion in the duodenal juice of offspring rats

OBJECTIVES

Studies on duodenal juice enzyme activities were carried out on suckling Wistar rats born to dams given ethanol during gestation and suckling. The results were compared with offspring of dams given diets containing no ethanol. Comparisons were also made with offspring of dams given ethanol and folic acid supplementation to observe whether a folate supplement could sufficiently reverse the negative effect of ethanol consumption.

METHODS

The dams were fed increased amounts of ethanol (5% to 20%, vol/vol) in tap water for 4 wk. The maximum quantity, 20% ethanol, was given to the dams during pregnancy and lactation. Offspring animals were randomized into three groups: control (CG), ethanol treated (EG), and ethanol plus folic acid (EFG).

RESULTS

Body weight at birth and at 21 d after birth and pancreatic weight were lower in offspring after ethanol treatment. Folic acid supplement increased these parameters in the EFG. Under basal conditions, decreases in amylase, lipase, and chymotrypsin activities in the duodenal juice after ethanol treatment were detected. Serum and urine amylase activities also decreased in the EG and EFG. These changes were different in the ethanol-treated progenitors. In these progenitors, ethanol treatment increased serum amylase levels. In the offspring, amylase activities in the EFG decreased with respect to the CG; however, an increase in the EG was observed. In dams the folic acid supplement did not significantly alter the serum amylase activities. Lipase and chymotrypsin activities in the EFG were similar to those in the EG. An increase of serum and urine amylase in the EFG with respect to the EG was found.

CONCLUSIONS

Our findings indicated that, under basal conditions, ethanol treatment during gestation and lactation negatively affects the digestive function in offspring. The effects of ethanol were slightly attenuated in rats supplemented with folic acid for amylase activities. Although extrapolation from animal studies can be tenuous, the present findings may explain the use of folic acid in the prevention of damage induced by ethanol to increase the amylase levels to physiologic concentrations.

Chronic pancreatitis

PURPOSE OF REVIEW

We are beginning to better understand the causes of chronic pancreatitis. This knowledge will hopefully lead to better diagnosis and treatment and abandonment of ill-conceived treatments. This review highlights contributions that moved the field toward these goals in the past year.

RECENT FINDINGS

Small steps have been made toward a better understanding of the molecular basis, particularly genetic causes, of the forms of chronic pancreatitis. Investigation of the role of stellate cells, an essential component of the fibrosis of chronic pancreatitis, has led to the finding that lovastatin inhibits stellate cell activation and could surface as a novel treatment of chronic pancreatitis. The clinical description of autoimmune pancreatitis has led to the realization that steroids are effective treatment for this form of chronic pancreatitis. Other treatments such as extracorporeal shock wave lithotripsy and endoscopic treatments have not been proved, because no controlled studies support these treatments over other treatments. The diagnosis of chronic pancreatitis may be enhanced by the new imaging technique of electronic pancreatoscopy whereby a 2.1-mm diameter scope can be advanced into the pancreatic duct through a duodenoscope. However, the data are too preliminary at this time to advocate this imaging procedure. A potential new endoscopic pancreatic function test may lead to more widespread use of function testing, but this test is not perfected and also cannot be advised for use at present.

SUMMARY

Ongoing basic and clinical research this past year has further characterized the genetic, molecular, and clinical aspects of chronic pancreatitis: efforts that may translate into novel therapies, once well-designed, controlled studies have been performed.

Genetic disorders of the pancreas

The venues opened to all by the remarkable studies of the genome are just starting to become manifest; they can now distinguish different variants of a disease; they are given the tools to better understand the pathophysiology of illness; they hope to be able to provide better treatment alternatives to our patients. The examples described in this review demonstrate the applicability of these concepts to pancreatic disorders. Researchers may be just scratching the surface at this time, but the potential is enormous. Many philosophic and ethical questions need to be answered as physicians move along: Should all family members of an index case be screened? Who should pay for testing? Who should get results? But, without the participation of so many patients, their family members, and numerous volunteers, researchers would not have witnessed the bridging of so many gaps as they have so far. All of us may now look forward to the application of this incredible knowledge to the therapeutic solutions so eagerly awaited.

Mutation analysis of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, the cationic trypsinogen (PRSS1) gene, and the serine protease inhibitor, Kazal type 1 (SPINK1) gene in patients with alcoholic chronic pancreatitis

Susceptibility to alcoholic chronic pancreatitis (ACP) could be genetically determined. Mutations in cationic trypsinogen (PRSS1), cystic fibrosis transmembrane conductance regulator (CFTR), and serine protease inhibitor, Kazal type 1 (SPINK1) genes have been variably associated with both the hereditary and the idiopathic form of chronic pancreatitis (CP). Our aim was to analyze the three genes in ACP patients. Mutational screening was performed in 45 unrelated ACP patients and 34 patients with alcoholic liver disease (ALD). No mutation of PRSS1 was found in ACP and ALD patients. Three mutations of CFTR were detected in four ACP patients with a prevalence (8.9%) not significantly different from that observed (3.0%) in ALD patients and from that expected (3.2%) in our geographical area. Neither compound heterozygotes for CFTR nor trans-heterozygotes for CFTR/SPINK1 were found. One ACP patient (2.2%) was found to carry the most common mutation (N34S) of SPINK1 compared to none of the ALD patients (P=NS). In five other patients (two with ACP and three with ALD) other rare variants, including P55S, were found. In contrast with the hereditary and the idiopathic forms of CP, in which mutations of PRSS1, CFTR, and SPINK1 genes may occur, ACP is still a "gene(s)-orphan" disease. The supposed genetic susceptibility to ACP relies on other yet unknown gene(s) which could affect the alcohol metabolism or modulate the pancreatic inflammatory response to alcohol abuse.

Regulation of pancreatic stellate cell function in vitro: biological and molecular effects of all-trans retinoic acid

Pancreatic stellate cells (PSCs) are essentially involved in the development of pancreatic fibrosis, a constant feature of chronic pancreatitis and pancreatic cancer. Profibrogenic mediators, such as ethanol metabolites and cytokines, induce a PSC activation process that involves proliferation, enhanced production of extracellular matrix proteins and a phenotypic transition towards myofibroblasts which includes a loss of the characteristic retinoid-containing fat droplets. Here, we have analysed how exogenous all-trans retinoic acid (ATRA) affects activation of rat PSCs induced by sustained culture. Bromodeoxyuridine-incorporation assays indicated an ATRA-dependent inhibition of DNA synthesis. In contrast, ATRA did not affect expression of alpha-smooth muscle actin, a protein typical for myofibroblasts. Quantification of [3H]proline incorporation revealed a diminished collagen production in ATRA-treated PSCs. Furthermore, zymography experiments showed that supernatants of ATRA-exposed PSC cultures contained higher levels of matrix metalloproteinase-9 but not of matrix metalloproteinase-2 than untreated controls. At the level of intracellular signalling, ATRA had no effect on extracellular signal-regulated kinase activation after incubation of PSCs with the mitogen platelet-derived growth factor (PDGF). In addition, PDGF-induced DNA binding of activator protein-1 (AP-1) transcription factors was not inhibited by ATRA treatment. Luciferase reporter gene assays, however, revealed an ATRA-dependent transrepression of AP-1 in PDGF-stimulated PSCs. Together, the results indicate that exogenous ATRA displays inhibitory effects on PSC proliferation and collagen synthesis but does not block phenotypic transition towards myofibroblasts. We hypothesise that inhibition of AP-1 signalling may be involved in the mediation of biological effects of ATRA on PSCs.

Genetic polymorphisms in alcoholic pancreatitis

Chronic, excessive alcohol consumption is clearly associated with acute and chronic pancreatitis. However, both clinical and laboratory studies have demonstrated that alcohol consumption alone does not directly cause pancreatitis. Growing evidence suggests that environmental and possibly genetic cofactors must also be present before the mechanisms protecting the pancreas from pancreatitis are circumvented and pancreatitis develops. The discovery that mutations in the cationic trypsinogen gene (R122H, N29I) predisposed to acute and chronic pancreatitis focused attention on possible genetic predispositions. Mutations in the cationic trypsinogen gene, however, are rarely associated with alcoholic chronic pancreatitis. Mutations in the SPINK1 gene (e.g. N34S) provide a threefold increased risk, and cystic fibrosis transmembrane conductance regulator (CFTR) mutations continue to be investigated. However, the major cofactor associated with alcoholic chronic pancreatitis is yet to be identified.

Alcohol-induced pancreatic injury

Alcoholic pancreatitis is a major complication of alcohol abuse. Until recently, it was generally accepted that alcoholic pancreatitis was a chronic disease from the outset. However, evidence is now emerging in support of the 'necrosis-fibrosis' hypothesis that alcoholic pancreatitis begins as an acute process and that repeated episodes of acute injury lead to the changes of chronic pancreatitis (acinar atrophy and fibrosis) resulting in exocrine and endocrine dysfunction. The treatment of acute pancreatitis follows the regimen of bed rest, nasogastric suction, analgesia and intravenous support. The role of additional therapeutic measures such as prophylactic antibiotics, antioxidants and enteral nutrition in severe cases has not yet been precisely defined. The treatment of chronic pancreatitis involves attention to its three cardinal features: pain, maldigestion and diabetes. With respect to the pathogenesis of alcoholic pancreatitis, the focus of research over the past 30 years has shifted from the sphincter of Oddi and ductular abnormalities to the acinar cell itself. It has now been established that the acinar cell is capable of metabolizing alcohol and that direct toxic effects of alcohol and/or its metabolites on acinar cells may predispose the gland to injury in the presence of an appropriate trigger factor. A significant recent development relates to the characterization of pancreatic stellate cells, increasingly implicated in alcoholic pancreatic fibrosis. This chapter summarizes the natural history, clinical features, current trends in treatment as well as recent advances in our understanding of the pathogenesis of alcoholic pancreatitis.

Use of an "acetaldehyde clamp" in the determination of low-KM aldehyde dehydrogenase activity in H4-II-E-C3 rat hepatoma cells

The high-affinity (K(M)<1 microM) mitochondrial class 2 aldehyde dehydrogenase (ALDH2) metabolizes most of the acetaldehyde generated in the hepatic oxidation of ethanol. H4-II-E-C3 rat hepatoma cells have been found to express ALDH2. We report a method to assess ALDH2 activity in intact hepatoma cells that does not require mitochondrial isolation. To determine only the high-affinity ALDH2 activity it is necessary to keep constant low concentrations of acetaldehyde in the cells to minimize its metabolism by high-K(M) aldehyde dehydrogenases. To maintain both low and constant concentrations of acetaldehyde we used an "acetaldehyde clamp," which keeps acetaldehyde at a concentration of 4.2+/-0.4 microM. The clamp is attained by addition of excess yeast alcohol dehydrogenase, 14C-ethanol, and oxidized form of nicotinamide adenine dinucleotide (NAD(+)) to the hepatoma cell culture medium. The concentration of 14C-acetaldehyde attained follows the equilibrium constant of the alcohol dehydrogenase reaction. Thus, 14C-acetate is generated virtually by the low-K(M) aldehyde dehydrogenase activity. 14C-acetate is separated from the culture medium by an anionic resin and its radioactivity is determined. We showed that (1) acetate production is linear for 120 min, (2) addition of 160 microM cyanamide to the culture medium leads to a 75%-80% reduction of acetate generated, and (3) ALDH2 activity is dependent on cell-to-cell contact and increases after cells reach confluence. The clamp system allows the determination of ALDH2 activity in less than one million H4-II-E-C3 rat hepatoma cells. The specificity and sensitivity of the "acetaldehyde clamp" assay should be of value in evaluation of the effects of new agents that modify Aldh2 gene expression, as well as in the study of ALDH2 regulation in intact cells.

Pancreatic stellate cell activation by ethanol and acetaldehyde: is it mediated by the mitogen-activated protein kinase signaling pathway?

BACKGROUND

Pancreatic fibrosis is a characteristic feature of alcoholic chronic pancreatitis. Recent studies suggest that activated pancreatic stellate cells (PSCs) are the major cell-type involved in pancreatic fibrogenesis. Cultured PSCs become activated when exposed to ethanol or its metabolite acetaldehyde (as indicated by increased alpha-smooth muscle actin [alpha-SMA] expression and increased collagen synthesis). However the intracellular signaling mechanisms responsible for ethanol- or acetaldehyde-induced PSC activation remain to be fully elucidated. One of the major signaling pathways known to regulate protein synthesis in mammalian cells is the mitogen-activated protein kinase (MARK) pathway.

AIMS

To examine the effects of ethanol and acetaldehyde on the MAPK pathway (by assessing the activities of the 3 major subfamilies (extracellular-regulated kinases 1 and 2 [ERK 1/2], JNK and p38 kinase) in PSCs and to examine the role of p38 kinase in mediating the ethanol- and acetaldehyde-induced increase in alpha-SMA expression in activated rat PSCs.

METHODS

Rat PSCs were incubated with ethanol (50 mM) or acetaldehyde (200 microM) for 15 min, 30 min, 60 min, and 24 h; and activities of ERK 1/2, JNK, and p38 kinase were assessed in cell lysates using kinase assays and Western blot. In addition, rat PSCs were treated with the specific p38 MAPK inhibitor SB203580 in the presence or absence of ethanol or acetaldehyde for 24h, and activation of the downstream protein kinase MAPKAP kinase-2 (an indicator of p38 MAPK activity) was assessed by Western blot. Specific inhibitors were also used to inhibit the activity of ERK 1/2 and JNK. Following inhibition of the above signaling pathways, alpha-SMA expression by PSCs was assessed by Western blot.

RESULTS

Ethanol and acetaldehyde increased the activation of all 3 subfamilies (ERK 1/2, JNK and p38 kinase) of the MAPK pathway in PSCs. Treatment of PSCs with SB203580 abolished the ethanol- and acetaldehyde-induced increase in p38 MAPK activity and also prevented the induction of alpha-SMA expression in PSCs. However, inhibition of ERK 1/2 and JNK had no effect on ethanoland acetaldehyde-induced alpha-SMA expression in PSCs.

CONCLUSIONS

(1) The MAP kinase pathway is induced in PSCs after exposure to ethanol or acetaldehyde and this induction is sustained for at least 24h. (2) The p38 MAPK pathway mediates the activation (as indicated by increased alpha-SMA expression) of PSCs by ethanol or acetaldehyde.

Animal models in gastrointestinal alcohol research-a short appraisal of the different models and their results

Alcohol-related diseases of the gastrointestinal tract play an important role in clinical gastroenterology. However, the mechanisms and pathophysiology underlying the effects of ethanol on the organs of the digestive tract are not yet completely understood. Animal models represent an essential tool for investigating alcohol-related diseases because they give researchers the opportunity to use methods that cannot be used in humans, such as knockout technology. However, there is still a need for new animal models resembling the human condition, since for some alcohol-related diseases such as chronic alcoholic pancreatitis, the ideal animal model does not yet exist. In this chapter, we provide an overview of the most commonly used animal models in gastrointestinal alcohol research. We will also briefly discuss the current concepts of the pathophysiological mechanisms involved in acute and chronic alcoholic damage of the oesophagus, stomach, small and large intestine, pancreas and liver.

Pancreas: healing response in critical illness

OBJECTIVE

The pathophysiology of acute pancreatitis represents a diverse mix of congenital, hereditary, and acquired problems associated with or causing acute pancreatic inflammation. Acute pancreatitis is characterized by acinar cell injury that may involve regional and systemic inflammatory responses. The systemic manifestations of acute pancreatitis are responsible for the majority of pancreatitis-associated morbidity and are due to the actions of specific inflammatory cytokines. This report summarizes this pancreatic injury, the role of cytokines in the pathogenesis of acute pancreatitis, and the pancreatic healing response that follows.

DESIGN

A comprehensive literature review of experimental pancreatitis as well as reports of cytokine involvement and healing response during clinical pancreatitis was performed.

RESULTS

Histamine release, bradykinin generation, and cytokine release play a significant role during acute pancreatic inflammation. Following an experimental insult, there is rapid expression of tumor necrosis factor-alpha, interleukin-6, interleukin-1, and chemokines by pancreatic acinar cells and/or transmigrated leukocytes. Preventing the action of these mediators has a profound beneficial effect in experimental animals. Pancreatic fibrosis is a central histologic response after pancreatitis. Transient collagen deposition with acinar necrosis occurs in acute pancreatitis; in chronic pancreatitis, permanent and disorganized pancreatic fibrosis and parenchymal cell atrophy occur.

CONCLUSIONS

Inflammatory mediators are responsible for the systemic manifestations of acute pancreatitis and the associated distant organ dysfunction. After the acute injury, regeneration or pancreatic repair is characterized by decreased release of proinflammatory mediators and decreased infiltrating inflammatory cells. Differentiation and proliferation of pancreatic myofibroblasts or "stellate" cells may be responsible for increased extracellular matrix production. The predictable nature in which the inflammation and fibrosis are produced may stimulate novel approaches to disease treatment.

Peroxisome proliferator-activated receptor alpha (PPARalpha) agonist treatment reverses PPARalpha dysfunction and abnormalities in hepatic lipid metabolism in ethanol-fed mice

Proper function of the peroxisome proliferator-activated receptor alpha (PPARalpha) is essential for the regulation of hepatic fatty acid metabolism. Fatty acid levels are increased in liver during the metabolism of ethanol and should activate PPARalpha. However, recent in vitro data showed that ethanol metabolism inhibited the function of PPARalpha. We now report that ethanol feeding impairs fatty acid catabolism in the liver in part via blocking PPARalpha-mediated responses in C57BL/6J mice. Ethanol feeding decreased PPARalpha/retinoid X receptor alpha binding in electrophoretic mobility shift assay of liver nuclear extracts. mRNAs for PPAR-regulated genes were reduced (long chain and medium chain acyl-CoA dehydrogenases) or failed to be induced (acyl-CoA oxidase, liver carnitine palmitoyl-CoA transferase, very long chain acyl-CoA synthetase, very long chain acyl-CoA dehydrogenase) in livers of the ethanol-fed animals, and ethanol feeding did not increase the rate of fatty acid beta-oxidation. Wy14,643, a PPARalpha agonist, restored the DNA binding activity of PPARalpha/retinoid X receptor alpha, induced mRNA levels of PPARalpha target genes, stimulated the rate of fatty acid beta-oxidation, and prevented fatty liver in ethanol-fed animals. Impairment of PPARalpha function during ethanol consumption contributes to the development of alcoholic fatty liver, which can be overcome by Wy14,643.

Alcohol dehydrogenase (ADH) isoenzymes and aldehyde dehydrogenase (ALDH) activity in the human pancreas

Ethanol metabolism in the pancreas occurs predominantly by way of an nonoxidative pathway to fatty acid ethyl esters but oxidative routes to acetaldehyde also may contribute to injury of pancreatic cells. Three metabolic systems are responsible for the oxidative metabolism of ethanol, among which the cytochrome P-4502E1 and alcohol dehydrogenase have been found in the pancreas. The aims of this study were to detect ADH and ALDH in the human pancreas and to assess which ADH isoenzymes are present in this organ. ADH activity was measured by the photometric method and ADH isoenzyme activity was determined using sensitive and specific substrates. ALDH activity was measured by the fluorometric method. We have shown that the activities of ADH and ALDH are present in the pancreas, although the activity of ALDH was not proportionally as low as ADH activity. The class III isoenzyme exhibited the highest activity of all ADH isoenzymes tested and it was about 7 times higher than the activity of class I. The activities of classes II and IV were low. The activities of ADH isoenzymes of classes I, II, and III in the pancreas of men were significantly higher than in women. This study demonstrates that alcohol dehydrogenase and aldehyde dehydrogenase are present in the pancreas.

Ethanol administration generates oxidative stress in the pancreas and liver, but fails to induce heat-shock proteins in rats

BACKGROUND

Heat-shock proteins (HSP) play an essential role in the sequestration and reparation of denatured cellular proteins. Because ethanol treatment can result in oxidative stress-induced protein damage, it is possible that expression of HSP is altered after ethanol consumption. Dose-response and time-course studies were performed to investigate whether acute and chronic intragastric ethanol administration can induce tissue damage, oxidative stress and expression of the heat-shock proteins HSP60 and HSP72 in the pancreas and liver of male Wistar rats.

METHODS

Laboratory and morphological analysis of pancreatic and liver damage were investigated. The degree of oxidative stress was assessed by measurement of the reduced glutathione content, lipid peroxidation and protein oxidation. The levels of HSP were examined by western blot analysis.

RESULTS

Ethanol administration dose- and time-dependently elevated the serum ethanol concentration and hepatic enzyme activities. Chronic ethanol treatment also resulted in morphological damage of the liver. We observed that acute and chronic ethanol consumption had markedly different effects on the oxidative parameters in the pancreas and liver. Acute ethanol administration caused oxidative stress in the liver, whereas there was no such effect in the pancreas. In contrast, chronic ethanol feeding resulted in oxidative stress in both the pancreas and the liver. Furthermore, neither acute nor chronic ethanol intake induced the synthesis of HSP, a major defense system against cellular damage in the examined organs.

CONCLUSION

Ethanol administration generates oxidative stress in the pancreas and liver, but fails to induce HSP in rats.

Production and effects of endothelin-1 in rat pancreatic stellate cells

INTRODUCTION

Proliferation and matrix synthesis of activated pancreatic stellate cells (PSCs) participate in the development of chronic pancreatitis. Besides other substances, endothelin-1 (ET-1) may influence the activation process of PSCs. Until now, ET-1 has not been studied in this particular cell type.

AIMS

To characterize PSCs in rat pancreas with respect to expression of ET(A)-receptors, production of ET-1, and physiological effects induced by ET-1 during PSC activation.

METHODOLOGY

Immunocytochemical and ELISA techniques and cDNA microarray analysis were used. Physiologic effects were characterized by single cell measurements of free cytosolic Ca2+-concentration and of PSC contractility on collagen lattices.

RESULTS

Activation of PSCs in vitro, as assessed by alpha-smooth muscle actin expression, was accompanied by the de novo expression of ET(A)-receptors and synthesis of ET-1 mRNA and protein. Cytosolic Ca2+-concentration was increased upon ET-1 stimulation in activated but not in quiescent PSCs. Contractility of activated PSCs was significantly reduced by the selective ET(A)-receptor antagonist BQ123 but not by the ET(B)-receptor antagonist IRL-1038.

CONCLUSIONS

The results suggest that ET-1 may act as a paracrine and autocrine factor for activated PSCs and may mediate contractions of activated, but not quiescent, PSCs.

Halofuginone to treat fibrosis in chronic graft-versus-host disease and scleroderma

Chronic graft-versus-host disease (cGvHD) and systemic sclerosis (scleroderma [SSc]) share clinical characteristics, including skin and internal organ fibrosis. Fibrosis, regardless of the cause, is characterized by extracellular matrix deposition, of which collagen type I is the major constituent. The progressive accumulation of connective tissue results in destruction of normal tissue architecture and internal organ failure. In both SSc and cGvHD, the severity of skin and internal organ fibrosis correlates with the clinical course of the disease. Thus, there is an unmet need for well-tolerated antifibrotic therapy. Halofuginone is an inhibitor of collagen type I synthesis in cells derived from various tissues and species and in animal models of fibrosis in which excess collagen is the hallmark of the disease. Halofuginone decreased collagen synthesis in the tight skin mouse (Tsk) and murine cGvHD, the 2 experimental systems that show many features resembling those of human GvHD. Inhibition of collagen synthesis by halofuginone is achieved by inhibiting transforming growth factor beta-dependent Smad3 phosphorylation. Dermal application of halofuginone caused a decrease in collagen content at the treated site of a cGvHD patient, and reduction in skin scores was observed in a pilot study with SSc patients. The results of the human studies provide basis for using halofuginone treatment for dermal fibrosis. As a first step toward future treatment of internal organ involvement, an oral administration study was performed in which halofuginone was well tolerated and plasma levels surpassed the predicted therapeutic exposure.

An embryonic chick pancreas organ culture model: characterization and neural control of exocrine release

An embryonic chick (Gallus domesticus) whole-organ pancreas culture system was developed for use as an in vitro model to study cholinergic regulation of exocrine pancreatic function. The culture system was examined for characteristic exocrine function and viability by measuring enzyme release, and noting histological, morphological, and anti-amylase immuno-fluorescence staining changes over a series of incubation times. This embryonic culture system exhibits loss of viability and morphological degeneration after 12 h of incubation time. Characterization and development of this exocrine model system was an important aspect of this study. Assessment of the 18-day-old embryonic chick pancreas model clearly indicated biochemical and cholinergic functionality, and morphological integrity, of the tissue after 4-h incubation. This embryonic age and incubation period were utilized for all subsequent cholinergic studies. The in vitro model was used to study parasympathetic regulation of exocrine function via the muscarinc receptors present in the embryonic chick pancreas. The effects of synthetic muscarinic agonists (bethanechol and carbachol) and subtype-specific antagonists affected amylase release to varying degrees suggesting heterogeneity of receptors. The effects of the muscarinic receptor antagonists atropine (non-specific), pirenzepine (M(1)-selective) and 4-DAMP [4-diphenylacetoxy-N-methyl-piperidine methiodide] (M(3)-selective) on bethanechol-stimulated amylase release were examined. Atropine and 4-DAMP at concentrations of 2 microM and higher significantly inhibited (p<0.05) agonist-stimulated amylase release, while pirenzipine did not at 2 microM, but did at 200 microM. The M(3) subtype selective antagonist 4-DAMP (2 pM-2 mM) significantly inhibited (p<0.05) 5 mM bethanechol-stimulated amylase release at concentrations of 2 microM and greater (amylase activity decreased from 100.61 to 49.41 U/l/mg). The data suggest the existence of a muscarinic receptor subtype for the embryonic chick pancreas exocrine cells characteristic to the mammalian M(3) glandular subtype.

Cell migration: a novel aspect of pancreatic stellate cell biology

BACKGROUND

Pancreatic stellate cells (PSCs), implicated as key mediators of pancreatic fibrogenesis, are found in increased numbers in areas of pancreatic injury. This increase in PSC number may be due to increased local proliferation and/or migration of these cells from adjacent areas. The ability of PSCs to proliferate has been well established but their potential for migration has not been examined.

AIMS

Therefore, the aims of this study were to determine whether cultured rat PSCs have the capacity to migrate and, if so, to characterise this migratory capacity with respect to the influence of basement membrane components and the effect of platelet derived growth factor (PDGF, a known stimulant for migration of other cell types).

METHODS

Migration of freshly isolated (quiescent) and culture activated (passaged) rat PSCs was assessed across uncoated or Matrigel (a basement membrane-like substance) coated porous membranes (pore size 8 micro m) in the presence or absence of PDGF (10 and 20 ng/ml) in the culture medium. A checkerboard assay was performed to assess whether the effect of PDGF on PSC migration was chemotactic or chemokinetic.

RESULTS

Cell migration was observed with both freshly isolated and passaged PSCs. However, compared with passaged (culture activated) cells, migration of freshly isolated cells was delayed, occurring only at or after 48 hours of incubation when the cells displayed an activated phenotype. PSC migration through Matrigel coated membranes was delayed but not prevented by basement membrane components. PSC migration was increased by PDGF and this effect was predominantly chemotactic (that is, in the direction of a positive concentration gradient).

CONCLUSIONS

(i) PSCs have the capacity to migrate. (ii) Activation of PSCs appears to be a prerequisite for migration. (iii) PDGF stimulates PSC migration and this effect is predominantly chemotactic.

IMPLICATION

Chemotactic factors released during pancreatic injury may stimulate the migration of PSCs through surrounding basement membrane towards affected areas of the gland.

Inhibition of pancreatic stellate cell activation by the hydroxymethylglutaryl coenzyme A reductase inhibitor lovastatin

Pancreatic stellate cells (PSCs) play a key role in pancreatic fibrosis, a constant feature of chronic pancreatitis. PSC activation occurs in response to profibrogenic mediators such as cytokines and involves proliferation, transition towards a myofibroblastic phenotype and enhanced production of extracellular matrix proteins. Previously, we have shown that PSC activation correlates with the activity of the Ras-Raf-ERK (extracellular signal-regulated kinase) signalling cascade [Gut 51 (2002) 579]. Using a rat culture model of PSCs, we have now evaluated the effects of lovastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor that interferes with protein isoprenylation, on PSC viability and activation as well as on signalling through Ras proteins. Apoptotic cells were detected applying the TUNEL assay. Proliferation of PSCs was quantitated using the bromodeoxyuridine DNA incorporation assay. Expression of alpha-smooth muscle actin (an indicator of the myofibroblastic phenotype), ERK activation and membrane translocation of the Ras superfamily member RhoA were analysed by immunoblotting. Lovastatin inhibited serum- and platelet-derived growth factor-stimulated PSC proliferation in a dose-dependent manner. At drug concentrations above the level required for growth inhibition, a strong increase of apoptotic cells was observed. Furthermore, lovastatin inhibited induction of alpha-smooth muscle actin expression in the course of primary culture. Immunoblot experiments indicated that lovastatin suppressed both Ras-mediated ERK 1/2 activation and platelet-derived growth factor-induced membrane translocation of RhoA. Together, our data suggest that lovastatin, through the interruption of Ras signalling, interferes with PSC activation. The antifibrotic efficiency of statins should be tested in animal models of chronic pancreatitis.

Overexpression of heparin-binding EGF-like growth factor in mouse pancreas results in fibrosis and epithelial metaplasia

BACKGROUND & AIMS

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is expressed in both normal pancreatic islets and in pancreatic cancers, but its role in pancreatic physiology and disease is not known. This report examines the effects of HB-EGF overexpression in mouse pancreas.

METHODS

Transgenic mice were established using a tissue-specific promoter to express an HB-EGF complementary DNA in pancreatic beta cells, effectively elevating HB-EGF protein 3-fold over endogenous levels.

RESULTS

Mice overexpressing HB-EGF in pancreatic islets showed both endocrine and exocrine pancreatic defects. Initially, islets from transgenic mice failed to segregate alpha, beta, delta, and PP cells appropriately within islets, and had impaired separation from ducts and acini. Increased stroma was detected within transgenic islets, expanding with age to cause fibrosis of both endocrine and exocrine compartments. In addition to these structural abnormalities, subsets of transgenic mice developed profound hyperglycemia and/or proliferation of metaplastic ductal epithelium. Both conditions were associated with severe stromal expansion, suggesting a role for islet/stromal interaction in the onset of the pancreatic disease initiated by HB-EGF. Supporting this conclusion, primary mouse fibroblasts adhered to transgenic islets when the 2 tissues were cocultured in vitro, but did not interact with nontransgenic islets.

CONCLUSIONS

An elevation in HB-EGF protein in pancreatic islets led to altered interactions among islet cells and among islets, stromal tissues, and ductal epithelium. Many of the observed phenotypes appeared to involve altered cell adhesion. These data support a role for islet factors in the development of both endocrine and exocrine disease.

Immunocytes and activated stellate cells in pancreatic fibrogenesis

INTRODUCTION AND AIMS

Chronic pancreatitis is a progressive chronic inflammatory disease characterized by irreversible destruction of exocrine pancreatic tissue and extensive fibrosis. Excessive alcohol consumption has been identified as the main etiologic factor of this disease in the Western world. Idiopathic pancreatitis accounts for approximately 30% of cases. An autoimmune mechanism may be involved in some patients, but this concept has not been generally accepted as a new clinical entity. The purpose of this work was to investigate the pathogenesis of pancreatic fibrosis and to establish the role of immunocytes and activated stellate cells in chronic pancreatitis, which was categorized into three groups: chronic alcoholic pancreatitis (AP), chronic idiopathic pancreatitis (IP), and chronic pancreatitis in the presence of pancreatic cancer (CA).

METHODOLOGY

Fifty-one pancreatic tissue samples were studied histopathologically and immunohistochemically (AP, 16 samples; IP, 12; CA, 12; and samples of tissue with apparently normal pancreatic histology, 11). The following immunohistochemical stains were used: alpha-smooth muscle antibody, desmin, and synaptophysin, as markers of activated stellate cells; and laminin, fibronectin, and collagen IV, as markers of extracellular matrix (ECM) proteins. Immunocytes were stained with antibody to LCA, CD68 antibody (macrophages), and CD8 antibody (natural killer T cell subset), and mast cells were examined using the Giemsa method. Positively stained macrophages, lymphocytes, and mast cells were counted in three high-power fields of a light microscope. The immunoreactivity of activated stellate cells and ECM proteins was assessed by a semiquantitative method (0, lack of positive staining; 5, numerous cells with strong positive immunostaining). Results were assessed statistically.

RESULTS

We found no statistical differences between cases of AP, IP, and CA in terms of total lymphocyte count (mean numbers: 416, 418, and 407 per three high-power fields, respectively). The percentage of CD8+ T cells in IP was statistically higher than that in AP. The macrophage count was significantly higher in the IP group than in the AP and CA groups. The mast cell count was markedly higher in the IP group than in the other groups. The stellate cell markers alpha-smooth muscle antibody and desmin showed slightly higher immunoreactivity in IP. The immunopositivity for synaptophysin was also higher in the IP group. There was a positive correlation between alpha-smooth muscle antibody, desmin, and synaptophysin expression and the degree of fibrosis. ECM protein markers showed no statistically significant differences between the three groups.

CONCLUSION

Results of this work show that a significant number of IP cases might have an autoimmune etiology. There was a positive correlation between activated stellate cell marker expression and the degree of fibrosis.

Angiotensin-converting enzyme inhibitor attenuates pancreatic inflammation and fibrosis in male Wistar Bonn/Kobori rats

BACKGROUND & AIMS

Pancreatic stellate cells have some similarities to hepatic stellate cells and an intrinsic renin-angiotensin system is present in the pancreas and is enhanced in acute pancreatitis and chronic pancreatic hypoxia. We assessed the effects of lisinopril, an angiotensin-converting enzyme (ACE) inhibitor, on spontaneously occurring chronic pancreatitis.

METHODS

Lisinopril in drinking water (20, 50, or 200 mg/L) was administered to 10-week-old male Wistar Bonn/Kobori (WBN/Kob) rats for 10 weeks and then the inflammatory parameters, fibrosis, serum and pancreatic ACE activity, and expression of transforming growth factor-beta1 (TGF-beta1) messenger RNA (mRNA) as well as positive immunostaining for alpha-smooth muscle actin (alpha-SMA) were assessed.

RESULTS

Lisinopril attenuated gross alterations in the pancreas. This protective effect was confirmed quantitatively by significant increases in pancreatic weights and decreases in pancreatic myeloperoxidase (MPO) activity (an index of granulocyte infiltration), pancreatic hydroxyproline content (an index of collagen deposition), ratio of fibrous tissue, and histologic scores. Lisinopril significantly reduced serum ACE activity but it did not affect pancreatic activity. High doses of lisinopril suppressed the overexpression of TGF-beta1 mRNA measured by reverse-transcription polymerase chain reaction (RT-PCR) and decreased the number of alpha-SMA-positive cells (activated pancreatic stellate cells) in the pancreas.

CONCLUSIONS

Lisinopril alleviated chronic pancreatitis and fibrosis in male WBN/Kob rats. It suppressed the expression of TGF-beta1 mRNA, resulting in the prevention of pancreatic stellate cell activation, which may be involved in the observed protection. We propose that an ACE inhibitor may be useful for treating chronic pancreatitis.

Hereditary, familial, and idiopathic chronic pancreatitis are not associated with polymorphisms in the tumor necrosis factor alpha (TNF-alpha) promoter region or the TNF receptor 1 (TNFR1) gene

PURPOSE

Genetic alterations that are associated with acute and chronic pancreatitis remain to be identified.

METHODS

The authors investigated two functionally active tumor necrosis factor (TNF) promoter region polymorphisms at positions -238 and -308 and the entire coding region of the corresponding TNF receptor 1 (TNFR1) gene in 54 patients with hereditary, familial, and idiopathic chronic pancreatitis who were previously tested negative for cationic trypsinogen mutations by direct DNA sequencing.

RESULTS

In three patients, we detected novel DNA variants in the TNFR1 gene that did not segregate with the disease. The genotype frequencies of the TNF promoter polymorphisms were similar between patients and controls.

CONCLUSION

These polymorphisms are not associated with hereditary, familial, or idiopathic chronic pancreatitis.

Oleic acid-induced pancreatitis alters expression of transforming growth factor-beta1 and extracellular matrix components in rats

INTRODUCTION AND AIMS

Extracellular matrix (ECM) components participate in the process of tissue repair and development of fibrosis in the pancreas. We studied the production kinetics of ECM components and transforming growth factor (TGF)-beta1 and identified their production sites in the pancreas following pancreatitis.

METHODOLOGY

Pancreatitis was induced in rats by a single intraductal infusion of oleic acid. Gene expression of TGF-betas and ECM components was studied by northern blotting. Pancreatic stellate cell activation was assessed by immunostaining for alpha-smooth muscle actin (alphaSMA) and desmin.

RESULTS

Gene expression of TGF-betas and ECM components was increased in association with pancreatic fibrosis after 1-2 weeks and remained higher than the control levels for the ensuing 12 weeks. Both alphaSMA and desmin were strongly immunostained around small vessels and faintly stained in mesenchymal cells and tubular complexes at 1 week. The combination of staining for alphaSMA plus in situ hybridization for procollagen type III mRNA revealed that procollagen type III mRNA was expressed in both alphaSMA-positive and alphaSMA-negative cells in the mesenchyma.

CONCLUSIONS

Our findings demonstrate that expression of genes for both TGF-betas and ECM components was increased and that both alphaSMA-positive myofibroblasts and mesenchymal cells are the major sources of ECM components after pancreatitis.

Rat pancreatic stellate cells secrete matrix metalloproteinases: implications for extracellular matrix turnover

BACKGROUND

Pancreatic fibrosis is a characteristic feature of chronic pancreatic injury and is thought to result from a change in the balance between synthesis and degradation of extracellular matrix (ECM) proteins. Recent studies suggest that activated pancreatic stellate cells (PSCs) play a central role in pancreatic fibrogenesis via increased synthesis of ECM proteins. However, the role of these cells in ECM protein degradation has not been fully elucidated.

AIMS

To determine: (i) whether PSCs secrete matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) and, if so (ii) whether MMP and TIMP secretion by PSCs is altered in response to known PSC activating factors such as tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta1 (TGF-beta1), interleukin 6 (IL-6), ethanol, and acetaldehyde.

METHODS

Cultured rat PSCs (n=3-5 separate cell preparations) were incubated at 37 degrees C for 24 hours with serum free culture medium containing TNF-alpha (5-25 U/ml), TGF-beta1 (0.5-1 ng/ml), IL-6 (0.001-10 ng/ml), ethanol (10-50 mM), or acetaldehyde (150-200 micro M), or no additions (controls). Medium from control cells was examined for the presence of MMPs by zymography using a 10% polyacrylamide-0.1% gelatin gel. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to examine gene expression of MMP9 and the tissue inhibitors of metalloproteinases TIMP1 and TIMP2. Western blotting was used to identify a specific MMP, MMP2 (a gelatinase that digests basement membrane collagen and the dominant MMP observed on zymography) and a specific TIMP, TIMP2. Reverse zymography was used to examine functional TIMPs in PSC secretions. The effect of TNF-alpha, TGF-beta1, and IL-6 on MMP2 secretion was assessed by densitometry of western blots. The effect of ethanol and acetaldehyde on MMP2 and TIMP2 secretion was also assessed by this method.

RESULTS

Zymography revealed that PSCs secrete a number of MMPs including proteinases with molecular weights consistent with MMP2, MMP9, and MMP13. RT-PCR demonstrated the presence of mRNA for metalloproteinase inhibitors TIMP1 and TIMP2 in PSCs while reverse zymography revealed the presence of functional TIMP2 in PSC secretions. MMP2 secretion by PSCs was significantly increased by TGF-beta1 and IL-6, but was not affected by TNF-alpha. Ethanol and acetaldehyde induced secretion of both MMP2 and TIMP2 by PSCs.

CONCLUSIONS

Pancreatic stellate cells have the capacity to synthesise a number of matrix metalloproteinases, including MMP2, MMP9, and MMP13 and their inhibitors TIMP1 and TIMP2. MMP2 secretion by PSCs is significantly increased on exposure to the proinflammatory cytokines TGF-beta1 and IL-6. Both ethanol and its metabolite acetaldehyde increase MMP2 as well as TIMP2 secretion by PSCs.

IMPLICATION

The role of pancreatic stellate cells in extracellular matrix formation and fibrogenesis may be related to their capacity to regulate the degradation as well as the synthesis of extracellular matrix proteins.

Differential roles of signaling pathways for proliferation and migration of rat pancreatic stellate cells

Activated pancreatic stellate cells (PSCs) have recently been implicated in the pathogenesis of pancreatic fibrosis and inflammation. Accumulation of PSCs is a fundamental feature of pancreatic fibrosis, and platelet-derived growth factor (PDGF)-BB is the most potent mitogen for PSCs. But, the molecular mechanisms responsible for PDGF's actions in PSCs are largely unknown. In hepatic stellate cells, it has been established that activation of both phosphatidylinositol (PI) 3-kinase and extracellular-signal regulated kinase (ERK) pathways is required for PDGF-BB-induced proliferation and migration. The aim of this study was to elucidate the signaling pathways mediating PDGF-BB's actions in PSCs. PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype. Culture-activated PSCs expressed PDGF alpha- and beta-receptors. PDGF-BB induced autophosphorylation of its receptor, followed by the activation of PI 3-kinase, Akt, and ERK pathways. Activation of PI 3-kinase was not required for PDGF-BB-induced ERK activation. PDGF-BB induced approximately five-fold increase in proliferation and chemotaxis of PSCs. Inhibition of ERK pathway with PD98059 completely blocked proliferation, whereas PD98059 had a modest inhibitory effect on cell migration (approximately 50%). On the other hand, inhibition of PI 3-kinase pathway with wortmannin or LY294002 almost completely inhibited migration, but did not affect proliferation of PSCs. In conclusion, our results suggest that ERK pathway regulates proliferation and migration in response to PDGF-BB, whereas PI 3-kinase mediates cellular migration, but not proliferation of PSCs.

Animal models in alcoholic pancreatitis--what can we learn?

Although the majority of patients with chronic pancreatitis present a history of excessive alcohol consumption, the pathophysiology underlying chronic alcoholic pancreatitis remains poorly defined. Since experimental animal models represent helpful tools in understanding human disease, numerous laboratory studies have been designed to study the effects of alcohol on the pancreas. In the present article we summarize the existing animal models that have been used to investigate the effects of acute and chronic alcohol application on the development of morphological alterations and pancreatic injury. Despite considerable experimental effort, acute or chronic ethanol feeding alone failed to cause acute or chronic pancreatitis in animals. However, ethanol-feeding and the combination with other procedures has demonstrated several mechanisms that play a role in ethanol-induced pancreatic injury. Among these ethanol-induced alterations and mechanisms are the reduction of pancreatic blood-flow and microcirculation, damaging effects of ethanol metabolites, increased pancreatic acinar cell expression of digestive and lysosomal enzymes, increased glandular enzyme content, additional nutritional factors, pancreatic duct obstruction, and limitations of pancreatic regeneration. Although no satisfactory animal model for alcoholic pancreatitis has been developed, these animal models have provided insights in several factors that predispose the pancreas to development of pancreatic injury and contribute to alcoholic pancreatitis.

Mutations of the cationic trypsinogen gene in hereditary and non-hereditary pancreatitis

BACKGROUND/AIMS

Mutations in the cationic trypsinogen gene have been detected in patients with hereditary pancreatitis (HP). This study investigates the prevalence of the R122H, N29I, A16V and -28delTCC mutations in the common, non-hereditary forms of chronic pancreatitis and in a HP family.

METHODS

DNA was prepared from blood samples of 53 patients with chronic pancreatitis (36 alcoholic, 14 idiopathic and 3 hereditary), 20 alcoholic controls and 20 healthy, ethnically matched controls. The R122H and A16V mutations were identified by the polymerase chain reaction (PCR) and restriction enzyme digestion. A nested-PCR was used to identify the N29I mutation. The -28delTCC deletion and the C133807T polymorphism were sought by direct sequencing.

RESULTS

The R122H mutation was detected in 1 patient with alcoholic chronic pancreatitis and all 3 affected members of a HP family. The N29I, A16V and -28delTCC mutations were not detected in any of the study subjects. At the C133807T polymorphism, the C allele and C/C genotype were significantly increased in alcoholic chronic pancreatitis (p = 0.001 and p = 0.0004, respectively) while the T allele and CT genotype were significantly reduced (p = 0.001 and p = 0.004, respectively) compared to healthy controls.

CONCLUSIONS

Mutations of the cationic trypsinogen gene are rarely found in chronic pancreatitis patients of typical aetiology. Screening for these mutations should be considered in those with a family history consistent with hereditary pancreatitis but may also be appropriate in a well-defined subgroup of patients with non-hereditary chronic pancreatitis, i.e. those who have developed the disease before the age of 30.

Issues in hyperlipidemic pancreatitis

Hypertriglyceridemia (HTG) is a rare cause of pancreatitis. Pancreatitis secondary to HTG, presents typically as an episode of acute pancreatitis (AP) or recurrent AP, rarely as chronic pancreatitis. A serum triglyceride (TG) level of more than 1,000 to 2,000 mg/dL in patients with type I, IV, or V hyperlipidemia (Fredrickson's classification) is an identifiable risk factor. The typical clinical profile of hyperlipidemic pancreatitis (HLP) is a patient with a preexisting lipid abnormality along with the presence of a secondary factor (e.g., poorly controlled diabetes, alcohol use, or a medication) that can induce HTG. Less commonly, a patient with isolated hyperlipidemia (type V or I) without a precipitating factor presents with pancreatitis. Interestingly, serum pancreatic enzymes may be normal or only minimally elevated, even in the presence of severe pancreatitis diagnosed by imaging studies. The clinical course in HLP is not different from that of pancreatitis of other causes. Routine management of AP caused by hyperlipidemia should be similar to that of other causes. A thorough family history of lipid abnormalities should be obtained, and an attempt to identify secondary causes should be made. Reduction of TG levels to well below 1,000 mg/dL effectively prevents further episodes of pancreatitis. The mainstay of treatment includes dietary restriction of fat and lipid-lowering medications (mainly fibric acid derivatives). Experiences with plasmapheresis, lipid pheresis, and extracorporeal lipid elimination are limited.

Inhibition of p38 mitogen-activated protein kinase blocks activation of rat pancreatic stellate cells

Activated pancreatic stellate cells (PSCs) have recently been implicated in the pathogenesis of pancreatic fibrosis and inflammation. However, the signal transduction pathways in PSCs remain largely unknown. We examined the role of p38 mitogen-activated protein (MAP) kinase in the activation of PSCs. PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype. Activation of p38 MAP kinase was determined by Western blotting using anti-phosphospecific antibody. The effects of two p38 MAP kinase inhibitors, 4-(4-flurophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB203580) and 4-(4-flurophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole (SB202190), on the parameters of PSC activation, including proliferation, expression of alpha-smooth muscle actin, alpha1(I) procollagen, and prolyl 4-hydroxylase (alpha) genes, and monocyte chemoattractant protein-1 production were evaluated. Interleukin-1beta and platelet-derived growth factor-BB activated p38 MAP kinase. Platelet-derived growth factor-induced PSC proliferation was inhibited by SB203580 and SB202190. These reagents decreased alpha-smooth muscle actin protein expression, and alpha1(I) procollagen and prolyl 4-hydroxylase (alpha) mRNA levels. Treatment with these p38 MAP kinase inhibitors also resulted in inhibition of monocyte chemoattractant protein-1 expression. In addition, SB203580 inhibited spontaneous activation of freshly isolated PSCs in culture on plastic. Thus, inhibition of p38 MAP kinase modulated profibrogenic and proinflammatory actions in PSCs, implying a potential application of p38 MAP kinase inhibitors for the treatment of pancreatic fibrosis and inflammation.

ROC curves in evaluation of serum fibrosis indices for hepatic fibrosis

AIM: Use Receiver operating characteristic (ROC) curves to find out the relationship between serum level of hyaluronic acid (HA), type III procollagen (PCIII), N-terminal procollagen III peptide (PIIINP), laminin (LN), type IV collagen (C-IV) and hepatic fibrosis, as well as to determine their value in clinical practice.

METHODS: 114 serum samples from chronic hepatitis patients were assayed for fibrosis indices including HA, PCIII, PIIINP, LN and IV-C with radioimmunoassay (RIA). Liver biopsy was also performed in all these patients and the biopsy material was examined histopathologically.

RESULTS: ROC curves analysis showed that area under the curve (AUC) of PIIINP, HA, PCIII, C-IV and LN was 0.800, 0.728, 0.727, 0.583 and 0.463, respectively. The analysis also showed that PIIINP (r = 0.452), HA (r = 0.497) and PCIII (r = 0.404) have greater diagnosis performances than C-IV (r = 0.238) and LN (r = 0.128) according to fibrosis staging. The sensitivity of HA plus PIIINP was 55.1%, it was the most sensitive combination. Combined three or more than three indices that based on HA, the specificity was 100%. Using combination assays can improve the specificity, but its sensitivity was not high. Serum fibrosis indices increased as the grade of inflammation aggravated. But only PIIINP and PCIII had significant difference between G1 and G2 (PIIINP: 13.16 ± 8.07 vs 8.32 ± 5.09; PCIII: 164.22 ± 65.69 vs 138.23 ± 77.63). The coefficient correlation of the results of inflammation grade and fibrosis staging to HA was 0.525 and 0.553 respectively, that to PCIII, 0.446 and 0.412, that to LN, 0.234 and 0.194, and that to IV-C, 0.363 and 0.351, respectively.

CONCLUSION: Serum fibrosis indices can indicate tendency of hepatic fibrosis, but it cannot replace liver biopsy. However, as diagnostic markers, more efficient serum fibrosis indices for the diagnosis of hepatic fibrosis need to be explored.

The role of monocyte chemoattractant protein-1 in experimental chronic pancreatitis model induced by dibutyltin dichloride in rats

INTRODUCTION

Recently, dibutyltin dichloride (DBTC) was reported to induce pancreatic fibrosis within 28 days in rats, but it is not clear that the induced condition should be considered chronic pancreatitis.

AIM AND METHODOLOGY

The aim of this study was to clarify whether the pancreatic fibrosis induced by DBTC can be regarded as chronic pancreatitis. Furthermore, we examined the relation of monocyte chemoattractant protein-1 (MCP-1) to the development of pancreatic fibrosis in this model. DBTC solution was injected into the right jugular vein in rats, and biochemical and histologic changes were measured at days 1, 3, 7, 14, and 28.

RESULTS

Microscopically, inflammatory cell infiltration was evident in the pancreas at days 1 and 3, mononuclear cell infiltration was observed at days 7, 14, and 28, and pancreatic fibrosis was pronounced 7 days later. At day 28, interstitial fibrosis and atrophy of the gland and ductlike tubular complex had progressed. DBTC produced a significant decrease in the contents of pancreatic protein and amylase, whereas the pancreatic hydroxyproline content increased. Serum and pancreatic MCP-1 concentration significantly increased compared with the control group. Furthermore, the expression of PDGF mRNA in the pancreas increased following the MCP-1 elevation.

CONCLUSIONS

These results suggest that this experimental model of pancreatic fibrosis induced by DBTC in rats was useful as a chronic pancreatitis model and that MCP-1 may play an important role in the development of pancreatic fibrosis.