Cerulein upregulates ICAM-1 in pancreatic acinar cells, which mediates neutrophil adhesion to these cells

Optogenetic stimulation of the brainstem dorsal motor nucleus ameliorates acute pancreatitis

Introduction

Inflammation is an inherently self-amplifying process, resulting in progressive tissue damage when unresolved. A brake on this positive feedback system is provided by the nervous system which has evolved to detect inflammatory signals and respond by activating anti-inflammatory processes, including the cholinergic anti-inflammatory pathway mediated by the vagus nerve. Acute pancreatitis, a common and serious condition without effective therapy, develops when acinar cell injury activates intrapancreatic inflammation. Prior study has shown that electrical stimulation of the carotid sheath, which contains the vagus nerve, boosts the endogenous anti-inflammatory response and ameliorates acute pancreatitis, but it remains unknown whether these anti-inflammatory signals originate in the brain.

Methods

Here, we used optogenetics to selectively activate efferent vagus nerve fibers originating in the brainstem dorsal motor nucleus of the vagus (DMN) and evaluated the effects on caerulein-induced pancreatitis.

Results

Stimulation of the cholinergic neurons in the DMN significantly attenuates the severity of pancreatitis as indicated by reduced serum amylase, pancreatic cytokines, tissue damage, and edema. Either vagotomy or silencing cholinergic nicotinic receptor signaling by pre-administration of the antagonist mecamylamine abolishes the beneficial effects.

Discussion

These results provide the first evidence that efferent vagus cholinergic neurons residing in the brainstem DMN can inhibit pancreatic inflammation and implicate the cholinergic anti-inflammatory pathway as a potential therapeutic target for acute pancreatitis.

Pancreas and Adverse Drug Reactions: A Literature Review

Adverse drug reactions (ADRs) affecting the pancreas are a heterogeneous group of side effects that cause damage to pancreatic cells. Various mechanisms such as hypersensitization, sphincter of Oddi constriction, direct cytotoxic and metabolic effects on pancreatic cells, and dose-dependent idiosyncrasy lead to intrapancreatic activation of pancreatic enzymes resulting in drug-induced acute pancreatitis. Several medications have been linked with the development of pancreatic cancer. Pancreatic cancer may result from proinflammatory, proliferative, and antiapoptotic effects. Diabetogenic effect of drugs, which is understood as impairment of insulin secretion, may occur due to direct destruction of β cells, systemic toxicity affecting pancreatic islets and cell membrane glucose transporters, induction of Th1-type autoimmune response, and impairment of voltage-gated calcium channels in β cells, endoplasmic reticulum stress, and insulin signaling. A better understanding of ADRs that affect the pancreas may contribute to improving the awareness of clinicians and patients and reducing potential harmful side effects of implemented therapies.

Review of the physiological effects of Phyllomedusa bicolor skin secretion peptides on humans receiving Kambô

Kambô is an Amazonian ritual which includes the application of the defensive secretion of the Phyllomedusa bicolor frog to superficial burns made on the skin of human participants. The secretion, which contains a range of biologically active linear peptides, induces a short purgative experience that is extensively reported by participants to leave them with positive physical, emotional and spiritual after-effects. Various peptides identified in the secretion exert analgesic, vascular, and gastric effects in vivo, and antimicrobial and anti-cancer effects, among others, in vitro. While there has been some investigation into the physiological effects of various individual peptides isolated from the P. bicolor secretion, very little is known about the putative synergistic effects of concurrent administration of the complete substance through the transdermal methods used traditionally in the Kambô ritual. In this review and commentary, the authors summarize the existing biological information from animal research on peptides from the P. bicolor secretion, then consider the evidence in the context of Kambô administration to humans. The presented information suggests that specific peptides are likely to contribute to analogous physiological effects of Kambô in humans. The possibility that beyond their physiological action, the experiential or phenomenological component of these effects may have therapeutic applications is discussed, concluding with a consideration of the feasibility of human clinical research.

Dynamic Nomogram for Predicting Thrombocytopenia in Adults with Acute Pancreatitis

Objective

Thrombocytopenia increases the risk of hemorrhage in patients with acute pancreatitis (AP), leading to poor clinical outcomes. Currently, there is no reliable tool for the early assessment of thrombocytopenia in these patients. We aimed to develop a nomogram based on available clinical parameters and validate its efficacy in predicting thrombocytopenia.

Methods

This was a retrospective study. All the data were extracted from an electronic database from May 2018 to May 2019. Patients with a diagnosis of AP and staying in the intensive care unit for more than 3 days were retrospectively analyzed. A clinical signature was built based on reproducible features, using the least absolute shrinkage and selection operator method (LASSO), and logistic regression established the model (P < 0.05). Nomogram performance was determined by its discrimination, calibration, and clinical usefulness.

Results

A total of 594 eligible patients were enrolled, of whom 399 were allocated to the training sets and the 195 in the test sets. The clinical features, including blood urea nitrogen (BUN), fibrinogen (FIB), and antithrombase III, were significantly associated with the incidence of thrombocytopenia after acute pancreatitis (p < 0.05) in training sets. The individualized nomogram showed good discrimination in the training sample (area under the receiver operating characteristic curve [AUC], 0.881) and in the validation sample (AUC, 0.883) with good calibration.

Conclusion

The proposed nomogram has good performance for predicting thrombocytopenia in patients with acute pancreatitis and may facilitate clinical decision-making.

Effect of Hypoxia Preconditioned Adipose-Derived Mesenchymal Stem Cell Conditioned Medium on Cerulein-Induced Acute Pancreatitis in Mice

Purpose: Acute pancreatitis (AP) is an inflammatory disorder distinguished by tissue injury and inflammation of the pancreas. Using paracrine potential of mesenchymal stem cells (MSCs) provides a useful clinical approach in treating inflammatory diseases. We investigated the therapeutic effects of adipose-derived MSC conditioned medium (CM) and hypoxia preconditioned adipose-derived MSC conditioned medium (HCM) in cerulein-induced AP in mice.

Methods: AP was induced in C57BL/6 mice by intraperitoneal injection of cerulein (75 μg/ kg/h × 7 times). One hour following the last injection of cerulein, mice were treated with intraperitoneal injection of CM and HCM (500 µL/mice/30 min × 3 times). Twelve hours following the treatment, serum levels of amylase and lipase were measured. In addition, pancreas pathological changes, immunohistochemical examinations for evaluation of IL-6 expression and pancreatic myeloperoxidase (MPO) enzyme activity were analyzed.

Results: The in vitro results of the morphological, differentiation and immunophenotyping analyses confirmed that hypoxia preconditioned MSCs (HP-MSCs) conserve MSCs characteristics after preconditioning. However, HP-MSCs significantly expressed high mRNA level of hypoxia inducible factor 1-α and higher level of total protein. The in vivo findings of the current study showed that CM and HCM significantly reduced the amylase & lipase activity, the severity of pancreas tissue injury and the expression of IL-6 and MPO enzyme activity compared with the AP group. However, no significant difference between CM and HCM groups was demonstrated.

Conclusion: Use of CM and HCM can attenuate cerulein-induced AP and decrease inflammation in the pancreas tissue in AP mice.

Superoxide dismutase mimetic nanoceria restrains cerulein induced acute pancreatitis

Aim: The present study was carried out to assess the effect of nanoceria (NC) on pancreatic inflammation caused by cerulein. Methods: NC was characterized and in vitro studies were carried out in murine macrophages. The in vivo effects were tested on cerulein-induced pancreatitis. Results: In vitro treatment with NC remarkably protected macrophages from lipopolysaccharide-induced inflammation and oxidative stress as evident from the results of 2',7'-dichlorofluorescin diacetate, JC-1 and MitoSox staining. In vivo treatment with NC showed potent superoxide dismutase and catalase mimetic activity, antipancreatitis activity and improved histology. Furthermore, it reduced the expression of p65-NF-κB and acetylation of histone H3 at lysine K14, K56 and K79 residues. Conclusion: We for the first time, demonstrate that NC may be a promising candidate for the therapy of pancreatitis.

Adaptive Immune Cell Dysregulation and Role in Acute Pancreatitis Disease Progression and Treatment

Acute pancreatitis (AP) is an inflammation of the pancreas caused by various stimuli including excessive alcohol consumption, gallstone disease and certain viral infections. Managing specifically the severe form of AP is limited due to lack of an understanding of the complex immune events that occur during AP involving immune cells and inflammatory molecules such as cytokines. The relative abundance of various immune cells resulting from the immune dysregulation drives disease progression. In this review, we examine the literature on the adaptive immune cells in AP, the prognostic value of these cells in stratifying patients into appropriate care and treatment strategies based on cell frequency in different AP severities are discussed.

Autophagy, Inflammation, and Immune Dysfunction in the Pathogenesis of Pancreatitis

Pancreatitis is a common disorder with significant morbidity and mortality, yet little is known about its pathogenesis, and there is no specific or effective treatment. Its development involves dysregulated autophagy and unresolved inflammation, demonstrated by studies in genetic and experimental mouse models. Disease severity depends on whether the inflammatory response resolves or amplifies, leading to multi-organ failure. Dysregulated autophagy might promote the inflammatory response in the pancreas. We discuss the roles of autophagy and inflammation in pancreatitis, mechanisms of deregulation, and connections among disordered pathways. We identify gaps in our knowledge and delineate perspective directions for research. Elucidation of pathogenic mechanisms could lead to new targets for treating or reducing the severity of pancreatitis.

Chronic Pancreatitis: Current Status and Challenges for Prevention and Treatment

This paper reviews the current status of our understanding of the epidemiology, diagnosis, and management of the continuum of pancreatic diseases from acute and recurrent acute pancreatitis to chronic pancreatitis and the diseases that are often linked with pancreatitis including diabetes mellitus and pancreatic cancer. In addition to reviewing the current state of the field, we identify gaps in knowledge that are necessary to address to improve patient outcomes in these conditions.

Capsaicin-Sensitive Sensory Nerves Are Necessary for the Protective Effect of Ghrelin in Cerulein-Induced Acute Pancreatitis in Rats

Ghrelin was shown to exhibit protective and therapeutic effect in the gut. Aim of the study was to investigate the role of sensory nerves (SN) in the protective effect of ghrelin in acute pancreatitis (AP). Studies were performed on male Wistar rats or isolated pancreatic acinar cells. After capsaicin deactivation of sensory nerves (CDSN) or treatment with saline, rats were pretreated intraperitoneally with ghrelin or saline. In those rats, AP was induced by cerulein or pancreases were used for isolation of pancreatic acinar cells. Pancreatic acinar cells were incubated in cerulein-free or cerulein containing solution. In rats with intact SN, pretreatment with ghrelin led to a reversal of the cerulein-induced increase in pancreatic weight, plasma activity of lipase and plasma concentration of tumor necrosis factor-α (TNF-α). These effects were associated with an increase in plasma interleukin-4 concentration and reduction in histological signs of pancreatic damage. CDSN tended to increase the severity of AP and abolished the protective effect of ghrelin. Exposure of pancreatic acinar cells to cerulein led to increase in cellular expression of mRNA for TNF-α and cellular synthesis of this cytokine. Pretreatment with ghrelin reduced this alteration, but this effect was only observed in acinar cells obtained from rats with intact SN. Moreover, CDSN inhibited the cerulein- and ghrelin-induced increase in gene expression and synthesis of heat shock protein 70 (HSP70) in those cells. Ghrelin exhibits the protective effect in cerulein-induced AP on the organ and pancreatic acinar cell level. Sensory nerves ablation abolishes this effect.

Molecular Ghrelin System in the Pancreatic Acinar Cells: The Role of the Polypeptide, Caerulein and Sensory Nerves

Ghrelin (GHRL) is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R). Experimental studies showed that GHRL protects the stomach and pancreas against acute damage, but the effect of GHRL on pancreatic acinar cells was still undetermined. Aim: To investigate the effect of GHRL and caerulein on the functional ghrelin system in pancreatic acinar cells taking into account the role of sensory nerves (SN). Methods: Experiments were carried out on isolated pancreatic acinar cells and AR42J cells. Before acinar cells isolation, GHRL was administered intraperitoneally at a dose of 50 µg/kg to rats with intact SN or with capsaicin deactivation of SN (CDSN). After isolation, pancreatic acinar cells were incubated in caerulein-free or caerulein containing solution. AR42J cells were incubated under basal conditions and stimulated with caerulein, GHRL or a combination of the above. Results: Incubation of isolated acinar cells with caerulein inhibited GHS-R and GHRL expression at the level of mRNA and protein in those cells. Either in rats with intact SN or with CDSN, administration of GHRL before isolation of acinar cells increased expression of GHRL and GHS-R in those cells and reversed the caerulein-induced reduction in expression of those parameters. Similar upregulation of GHS-R and GHRL was observed after administration of GHRL in AR42J cells. Conclusions: GHRL stimulates its own expression and expression of its receptor in isolated pancreatic acinar cells and AR42J cells on the positive feedback pathway. This mechanism seems to participate in the pancreatoprotective effect of GHRL in the course of acute pancreatitis.

Effects of cerulein on keratin 8 phosphorylation and perinuclear reorganization in pancreatic cancer cells: Involvement of downregulation of protein phosphatase 2A and alpha4

Toxicants can perturb cellular homeostasis by modifying phosphorylation-based signaling. In the present study, we examined the effects of cerulein, an inducer of acute pancreatitis, on keratin 8 (K8) phosphorylation. We found that cerulein dose-dependently induced K8 phosphorylation and perinuclear reorganization in PANC-1 cells, thus leading to migration and invasion. The extracellular signal-regulated kinases (ERK) inhibitor U0126 suppressed cerulein-induced phosphorylation of serine 431 and reorganization of K8. Cerulein reduced the expressions of protein phosphatase 2A (PP2A) via ubiqutination and alpha4. PP2A's involvement in K8 phosphorylation of PANC-1 cells was also confirmed by the observation that PP2A gene silencing resulted in K8 phosphorylation and migration of PANC-1 cells. Overall, these results suggest that cerulein induced phosphorylation and reorganization through ERK activation by downregulating PP2A and alpha4, leading to increased migration and invasion of PANC-1 cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2090-2098, 2016.

PKD signaling and pancreatitis

BACKGROUND

Acute pancreatitis is a serious medical disorder with no current therapies directed to the molecular pathogenesis of the disorder. Inflammation, inappropriate intracellular activation of digestive enzymes, and parenchymal acinar cell death by necrosis are the critical pathophysiologic processes of acute pancreatitis. Thus, it is necessary to elucidate the key molecular signals that mediate these pathobiologic processes and develop new therapeutic strategies to attenuate the appropriate signaling pathways in order to improve outcomes for this disease. A novel serine/threonine protein kinase D (PKD) family has emerged as key participants in signal transduction, and this family is increasingly being implicated in the regulation of multiple cellular functions and diseases.

METHODS

This review summarizes recent findings of our group and others regarding the signaling pathway and the biological roles of the PKD family in pancreatic acinar cells. In particular, we highlight our studies of the functions of PKD in several key pathobiologic processes associated with acute pancreatitis in experimental models.

RESULTS

Our findings reveal that PKD signaling is required for NF-κB activation/inflammation, intracellular zymogen activation, and acinar cell necrosis in rodent experimental pancreatitis. Novel small-molecule PKD inhibitors attenuate the severity of pancreatitis in both in vitro and in vivo experimental models. Further, this review emphasizes our latest advances in the therapeutic application of PKD inhibitors to experimental pancreatitis after the initiation of pancreatitis.

CONCLUSIONS

These novel findings suggest that PKD signaling is a necessary modulator in key initiating pathobiologic processes of pancreatitis, and that it constitutes a novel therapeutic target for treatments of this disorder.

Therapeutic implications of innate immune system in acute pancreatitis

INTRODUCTION

Acute pancreatitis (AP) is an inflammatory disorder of the pancreas encompassing a cascade of cellular and molecular events. It starts from premature activation of zymogens with the involvement of innate immune system to a potential systemic inflammatory response and multiple organ failure. Leukocytes are the major cell population that participate in the propagation of the disease. Current understanding of the course of AP is still far from complete, limiting treatment options mostly to conservative supportive care. Emerging evidence has pointed to modulation of the immune system for strategic therapeutic development, by mitigating the inflammatory response and severity of AP. In the current review, we have focused on the role of innate immunity in the condition and highlighted therapeutics targeting it for treatment of this challenging disease.

AREAS COVERED

The current review has aimed to elaborate in-depth understanding of specific roles of innate immune cells, derived mediators and inflammatory pathways that are involved in AP. Summarizing the recent therapeutics and approaches applied experimentally that target immune responses to attenuate AP.

EXPERT OPINION

The current state of knowledge on AP, limitations of presently available therapeutic approaches and the promise of therapeutic implications of innate immune system in AP are discussed.

Acute Pancreatitis-Progress and Challenges: A Report on an International Symposium

An international symposium entitled "Acute pancreatitis: progress and challenges" was held on November 5, 2014 at the Hapuna Beach Hotel, Big Island, Hawaii, as part of the 45th Anniversary Meeting of the American Pancreatic Association and the Japanese Pancreas Society. The course was organized and directed by Drs. Stephen Pandol, Tooru Shimosegawa, Robert Sutton, Bechien Wu, and Santhi Swaroop Vege. The symposium objectives were to: (1) highlight current issues in management of acute pancreatitis, (2) discuss promising treatments, (3) consider development of quality indicators and improved measures of disease activity, and (4) present a framework for international collaboration for development of new therapies. This article represents a compilation and adaptation of brief summaries prepared by speakers at the symposium with the purpose of broadly disseminating information and initiatives.

Reserve stem cells: Differentiated cells reprogram to fuel repair, metaplasia, and neoplasia in the adult gastrointestinal tract

It has long been known that differentiated cells can switch fates, especially in vitro, but only recently has there been a critical mass of publications describing the mechanisms adult, postmitotic cells use in vivo to reverse their differentiation state. We propose that this sort of cellular reprogramming is a fundamental cellular process akin to apoptosis or mitosis. Because reprogramming can invoke regenerative cells from mature cells, it is critical to the long-term maintenance of tissues like the pancreas, which encounter large insults during adulthood but lack constitutively active adult stem cells to repair the damage. However, even in tissues with adult stem cells, like the stomach and intestine, reprogramming may allow mature cells to serve as reserve ("quiescent") stem cells when normal stem cells are compromised. We propose that the potential downside to reprogramming is that it increases risk for cancers that occur late in adulthood. Mature, long-lived cells may have years of exposure to mutagens. Mutations that affect the physiological function of differentiated, postmitotic cells may lead to apoptosis, but mutations in genes that govern proliferation might not be selected against. Hence, reprogramming with reentry into the cell cycle might unmask those mutations, causing an irreversible progenitor-like, proliferative state. We review recent evidence showing that reprogramming fuels irreversible metaplastic and precancerous proliferation in the stomach and pancreas. Finally, we illustrate how we think reprogrammed differentiated cells are likely candidates as cells of origin for cancers of the intestine.

What are the macrophages and stellate cells doing in pancreatic adenocarcinoma?

Pancreatic ductal adenocarcinoma is a devastating disease characterized by a dense desmoplastic stroma. Chemo- and radio-therapeutic strategies based on targeting cancer cells have failed in improving the outcome of this cancer suggesting important roles for stroma in therapy resistance. Cells in the tumor stroma have been shown to regulate proliferation, resistance to apoptosis and treatments, epithelial to mesenchymal transition (EMT) and stemness of cancer cells. Stellate cells in their activated state have been thought over the past decade to only have tumor promoting roles. However, recent findings suggest that stellate cells may have protective roles as well. The present review highlights the latest findings on the role of two major components of tumor stroma, pancreatic stellate cells and macrophages, in promoting or inhibiting pancreatic cancer, focused on their effects on EMT and cancer stemness.

Immune cells and immune-based therapy in pancreatitis

Alcohol and gallstones are the most common etiologic factors in acute pancreatitis (AP). Recurrent AP can lead to chronic pancreatitis (CP). Although the underlying pathophysiology of the disease is complex, immune cells are critical in the pathogenesis of pancreatitis and determining disease severity. In this review, we discuss the role of innate and adaptive immune cells in both AP and CP, potential immune-based therapeutic targets, and animal models used to understand our knowledge of the disease. The relative difficulty of obtaining human pancreatic tissue during pancreatitis makes animal models necessary. Animal models of pancreatitis have been generated to understand disease pathogenesis, test therapeutic interventions, and investigate immune responses. Although current animal models do not recapitulate all aspects of human disease, until better models can be developed available models are useful in addressing key research questions. Differences between experimental and clinical pancreatitis need consideration, and when therapies are tested, models with established disease ought to be included.

Tetraspanin CD9 is involved in pancreatic damage during caerulein-induced acute pancreatitis in mice

OBJECTIVE

Pancreatic acinar cell necrosis and subsequent inflammatory response aggravate acute pancreatitis (AP). Tetraspanin CD9 has been reported to mediate inflammatory signaling by regulating molecular organization at the cell surface. This study aimed to investigate the role of CD9 in caerulein-induced AP (CIP) in mice.

METHODS

The expression of CD9 was detected in CIP in mice in vivo and cholecystokinin (CCK)/recombinant mouse tumor necrosis factor (rmTNF)-α induced pancreatic acinar cell death in vitro by quantitative real-time polymerase chain reaction, Western blot and immunofluorescence. The roles of CD9 in pancreatic acinar cell death and inflammatory response were further studied through the deletion of CD9 expression using small interfering RNA (siRNA).

RESULTS

CD9 was markedly upregulated in pancreatic tissues in mice during the early onset of CIP and was located mainly at the pancreatic acinar cell surface, which was associated with pancreatic damage. Additionally, incubation with CCK or rmTNF-α directly increased the expression of CD9 in isolated mice pancreatic acinar cells in vitro. The deletion of CD9 expression partially reversed both pancreatic acinar cell death induced by CCK and mRNA levels of proinflammatory cytokines produced by damaged acinar cells.

CONCLUSION

These results indicate that increased CD9 expression may be involved in pancreatic injury, possibly via the promotion of cytokine expressions in CIP in mice.

Pharmacological induction of pancreatic islet cell transdifferentiation: relevance to type I diabetes

Type I diabetes (T1D) is an autoimmune disease in which an immune response to pancreatic β-cells results in their loss over time. Although the conventional view is that this loss is due to autoimmune destruction, we present evidence of an additional phenomenon in which autoimmunity promotes islet endocrine cell transdifferentiation. The end result is a large excess of δ-cells, resulting from α- to β- to δ-cell transdifferentiation. Intermediates in the process of transdifferentiation were present in murine and human T1D. Here, we report that the peptide caerulein was sufficient in the context of severe β-cell deficiency to induce efficient induction of α- to β- to δ-cell transdifferentiation in a manner very similar to what occurred in T1D. This was demonstrated by genetic lineage tracing and time course analysis. Islet transdifferentiation proceeded in an islet autonomous manner, indicating the existence of a sensing mechanism that controls the transdifferentiation process within each islet. The finding of evidence for islet cell transdifferentiation in rodent and human T1D and its induction by a single peptide in a model of T1D has important implications for the development of β-cell regeneration therapies for diabetes.

Protective effects of fucoidan, a P- and L-selectin inhibitor, in murine acute pancreatitis

OBJECTIVE

The objective of this study was to investigate the potential protective effects of fucoidan, an L- and P-selectin modulator, in 2 murine models of acute pancreatitis.

METHODS

Acute pancreatitis was induced in mice either by the retrograde infusion of taurolithocholic acid sulfate into the pancreatic duct or by intraperitoneal injections of cerulein (50 μg/kg per hour). The experimental groups received fucoidan (25 mg/kg, intravenously) before pancreatitis induction, whereas control groups received only saline. After 24 hours, serum amylase, lipase, interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and nitrite were measured. In addition, myeloperoxidase (MPO) activity (lung and pancreas) and histological assessment (pancreas) were determined.

RESULTS

Serum amylase, lipase, nitrite, TNF-α, and IL-1β, and pancreatic and lung MPO were increased in both taurolithocholic acid sulfate and cerulein acute pancreatitis compared with the respective control groups. Fucoidan significantly decreased the augmented levels of amylase, lipase, pancreatic and lung MPO, TNF-α, IL-1β, and nitrite in both models. Pancreas histological changes observed in both acute pancreatitis models were significantly attenuated by fucoidan.

CONCLUSIONS

Fucoidan reduced the severity of acute pancreatitis in mice by decreasing neutrophil infiltration and systemic inflammation, suggesting that modulation of selectins may constitute a promising therapeutic approach.

Overview of exocrine pancreatic pathobiology

Exocrine pancreas is a source of several enzymes that are essential for the digestive process. The exocrine pancreatic secretion is tightly regulated by the neuroendocrine system. The endocrine pancreas is tightly integrated anatomically and physiologically with the exocrine pancreas and modulates its function. Compound-induced pancreatitis is not a common event in toxicology or drug development, but it becomes a significant liability when encountered. Understanding the species-specific differences in physiology is essential to understand the underlying pathobiology of pancreatic disease in animal models and its relevance to human disease. This review will mainly focus on understanding the morphology and physiology of the pancreas, unique islet-exocrine interactions, and pancreatitis.

Inflammation, autophagy, and obesity: common features in the pathogenesis of pancreatitis and pancreatic cancer

Inflammation and autophagy are cellular defense mechanisms. When these processes are deregulated (deficient or overactivated) they produce pathologic effects, such as oxidative stress, metabolic impairments, and cell death. Unresolved inflammation and disrupted regulation of autophagy are common features of pancreatitis and pancreatic cancer. Furthermore, obesity, a risk factor for pancreatitis and pancreatic cancer, promotes inflammation and inhibits or deregulates autophagy, creating an environment that facilitates the induction and progression of pancreatic diseases. However, little is known about how inflammation, autophagy, and obesity interact to promote exocrine pancreatic disorders. We review the roles of inflammation and autophagy, and their deregulation by obesity, in pancreatic diseases. We discuss the connections among disordered pathways and important areas for future research.

Role of immune cells and immune-based therapies in pancreatitis and pancreatic ductal adenocarcinoma

Immune cells are important in the pathogenesis of acute pancreatitis and determine disease severity. Results from cytokine-based clinical trials for acute pancreatitis have been disappointing, so strategies that target and alter the behavior of infiltrating immune cells require consideration. Recurrent acute pancreatitis can progress to chronic pancreatitis, which is a well-described risk factor for pancreatic ductal adenocarcinoma (PDA). However, most patients with chronic pancreatitis do not develop PDA, and most patients with PDA do not have a history of pancreatitis. Interestingly, chronic pancreatitis and PDA tissues have similarities in their desmoplasia and inflammatory infiltrates, indicating overlapping inflammatory responses. Further studies are needed to determine the differences and similarities of these responses, improve our understanding of PDA pathogenesis, and develop specific immune-based therapies. Immune cells in PDA produce immunosuppressive signals that allow tumors to evade the immune response. Unlike single therapeutic agent studies that block immunosuppressive mechanisms, studies of combination therapies that include therapeutic vaccines have provided promising results.

Effects of dexamethasone on intercellular adhesion molecule 1 expression and inflammatory response in necrotizing acute pancreatitis in rats

OBJECTIVES

Adhesion molecules are involved in the inflammatory response during acute pancreatitis (AP). We investigated the effect of dexamethasone (Dx) on intercellular adhesion molecule 1 (ICAM-1) expression during AP and its consequences on leukocyte recruitment and pancreatic damage.

METHODS

Acute pancreatitis was induced in rats by 3.5% sodium taurocholate for 3 hours and 6 hours. Dexamethasone (1 mg/kg) was administered either 30 minutes before or 1 hour after inducing AP. Messenger RNA ICAM-1 expression in pancreas and lung, membrane-bound ICAM-1 in acinar cells, and ICAM-1 plasma levels were analyzed. Histological examination of the pancreas and neutrophil infiltration in pancreas and lung were also measured.

RESULTS

Prophylactic and therapeutic administration of Dx down-regulated ICAM-1 expression in pancreas and lung from early AP. Dexamethasone given before AP reduced the pancreatic damage, but lung inflammation was not prevented. Therapeutic Dx treatment was ineffective in avoiding leukocyte recruitment into the pancreas and lung in rats with AP. High ICAM-1 concentration was found in plasma during AP, which was not reduced by Dx treatments.

CONCLUSIONS

Dexamethasone down-regulates ICAM-1 expression, but it does not completely prevent leukocyte recruitment during sodium taurocholate-induced AP.

Inflammatory role of the acinar cells during acute pancreatitis

Pancreatic acinar cells are secretory cells whose main function is to synthesize, store and finally release digestive enzymes into the duodenum. However, in response to noxious stimuli, acinar cells behave like real inflammatory cells because of their ability to activate signalling transduction pathways involved in the expression of inflammatory mediators. Mediated by the kinase cascade, activation of Nuclear factor-κB, Activating factor-1 and Signal transducers and activators of transcription transcription factors has been demonstrated in acinar cells, resulting in overexpression of inflammatory genes. In turn, kinase activity is down-regulated by protein phosphatases and the final balance between kinase and phosphatase activity will determine the capability of the acinar cells to produce inflammatory factors. The kinase/phosphatase pair is a redox-sensitive system in which kinase activation overwhelms phosphatase activity under oxidant conditions. Thus, the oxidative stress developed within acinar cells at early stages of acute pancreatitis triggers the activation of signalling pathways involved in the up-regulation of cytokines, chemokines and adhesion molecules. In this way, acinar cells trigger the release of the first inflammatory signals which can mediate the activation and recruitment of circulating inflammatory cells into the injured pancreas. Accordingly, the role of acinar cells as promoters of the inflammatory response in acute pancreatitis may be considered. This concept leads to amplifying the focus from leukocyte to acinar cells themselves, to explain the local inflammation in early pancreatitis.

Pentoxifylline prevents loss of PP2A phosphatase activity and recruitment of histone acetyltransferases to proinflammatory genes in acute pancreatitis

Mitogen-activated protein kinases (MAPKs) are considered major signal transducers early during the development of acute pancreatitis. Pentoxifylline is a phosphodiesterase inhibitor with marked anti-inflammatory properties through blockade of extracellular signal regulated kinase (ERK) phosphorylation and tumor necrosis factor alpha production. Our aim was to elucidate the mechanism of action of pentoxifylline as an anti-inflammatory agent in acute pancreatitis. Necrotizing pancreatitis induced by taurocholate in rats and taurocholate-treated AR42J acinar cells were studied. Phosphorylation of ERK and ERK kinase (MEK1/2), as well as PP2A, PP2B, and PP2C serine/threonine phosphatase activities, up-regulation of proinflammatory genes (by reverse transcription-polymerase chain reaction and chromatin immunoprecipitation), and recruitment of transcription factors and histone acetyltransferases/deacetylases to promoters of proinflammatory genes (egr-1, atf-3, inos, icam, il-6, and tnf-alpha) were determined in the pancreas during pancreatitis. Pentoxifylline did not reduce MEK1/2 phosphorylation but prevented the marked loss of serine/threonine phosphatase PP2A activity induced by taurocholate in vivo without affecting PP2B and PP2C activities. The rapid loss in PP2A activity induced by taurocholate in acinar cells was due to a decrease in cAMP levels that was prevented by pentoxifylline. Pentoxifylline also reduced the induction of early (egr-1, atf-3) responsive genes and abrogated the up-regulation of late (inos, icam, il-6, tnf-alpha) responsive genes and recruitment of transcription factors (nuclear factor kappaB and C/EBPbeta) and histone acetyltransferases to their gene promoters during pancreatitis. In conclusion, the beneficial effects of pentoxifylline--and presumably of other phosphodiesterase inhibitors--in this disease seem to be mediated by abrogating the loss of cAMP levels and PP2A activity as well as chromatin-modifying complexes very early during acute pancreatitis.

Nelfinavir/ritonavir reduces acinar injury but not inflammation during mouse caerulein pancreatitis

There is no clinical treatment that reduces acinar injury during pancreatitis. Human immunodeficiency virus (HIV) protease inhibitors (PI), including nelfinavir (NFV) and ritonavir (RTV), may reduce the rate of pancreatitis in HIV-infected patients. Since permeability transition pore (PTPC)-mediated mitochondrial dysfunction occurs during pancreatitis, and we have shown that PI prevents PTPC opening, we studied its effects in a model of pancreatitis. The effect of NFV plus RTV (NFV/RTV) or vehicle on caerulein-induced pancreatitis in mice was compared by measuring changes in mitochondrial membrane potential in vitro and cytochrome c leakage in vivo. Histological and inflammatory makers were also compared. NFV/RTV improved DiOC6 retention in acini exposed to caerulein in vitro. In vivo NFV prevented cytosolic leakage of cytochrome c and reduced pancreatic acinar injury, active caspase-3 staining, TUNEL-positive acinar cells, and serum amylase (P < 0.05). Conversely, trypsin activity, serum cytokine levels, and pancreatic and lung inflammation were unaffected. NFV/RTV reduces pancreatic injury and acinar cell death in experimental mouse caerulein-induced pancreatitis but does not impact inflammation.

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.

Pathophysiological role of platelets and platelet system in acute pancreatitis

The most successful approach for restoring normal long-term glucose homeostasis in type I diabetes mellitus is whole-organ pancreas transplantation. Graft pancreatitis is observed in up to 20% of patients and may lead to loss of the transplanted organ. Several pathophysiological events have been implicated in this form of pancreatitis. The most important cause of early graft pancreatitis is ischemia/reperfusion (I/R)-related disturbance of microvascular perfusion with subsequent hypoxic tissue damage. Recently, considerable evidence accumulated that, among a variety of other pathophysiological events, the activation of platelets can contribute to I/R injury in the course of acute pancreatitis experimentally and clinically. This review summarizes the events affecting platelet function and, therefore, pancreatic microcirculation leading to acute pancreatitis. Therapeutic approaches and own results are presented.

Early induction of moderate hypothermia suppresses systemic inflammatory cytokines and intracellular adhesion molecule-1 in rats with caerulein-induced pancreatitis and endotoxemia

OBJECTIVES

To evaluate the systemic effects of moderate hypothermia (MH) and the timing of induction on acute pancreatitis (AP) and endotoxemia in rats.

METHODS

The effects of MH were compared in 4 groups, that is, sham group (38 degrees C), control group (38 degrees C), early MH group (32 degrees C on administration of lipopolysaccharide [LPS]), and delayed MH group (32 degrees C 1 hour after LPS). AP and endotoxemia were induced by intramuscular injection of caerulein and intraperitoneal injection of LPS.

RESULTS

Serum interleukin 6 (IL-6) in both MH groups was significantly lower than that in the control group at 3 hours. Serum interleukin 10 (IL-10) in the early MH group was significantly higher than those in the other 3 groups at 1 hour. IL-10/IL-6 ratios in both MH groups were significantly higher than that in the control group at 3 hours. Serum soluble intercellular adhesion molecule (sICAM-1) in both MH groups was significantly lower than that in the control group at 3 hours. Serum sICAM-1 in the early MH group was significantly lower than that in the delayed MH group. The tendency of pancreatic ICAM-1 was similar to that of serum sICAM-1.

CONCLUSIONS

Early induction of MH might be protective against pancreatic injury and systemic inflammation in AP and endotoxemia.

The tripeptide analog feG ameliorates severity of acute pancreatitis in a caerulein mouse model

Acute pancreatitis (AP) is associated with significant morbidity and mortality; however, there is no specific treatment for this disease. A novel salivary tripeptide analog, feG, reduces inflammation in several different animal models of inflammation. The aims of this study were to determine whether feG reduced the severity of AP and modifies the expression of pancreatic ICAM-1 mRNA during AP in a mouse model. AP was induced in mice by hourly (x12) intraperitoneal injections of caerulein. A single dose of feG (100 microg/kg) was coadministered with caerulein either at time 0 h (prophylactic) or 3 h after AP induction (therapeutic). Plasma amylase and pancreatic MPO activities and pancreatic ICAM-1 mRNA expression (by RT-PCR) were measured. Pancreatic sections were histologically assessed for abnormal acinar cells and interstitial space. AP induction produced a sevenfold increase in plasma amylase, a tenfold increase in pancreatic MPO activity, and a threefold increase in interstitial space, and 90% of the acinar cells were abnormal. Prophylactic treatment with feG reduced the AP-induced plasma amylase activity by 45%, pancreatic MPO by 80%, the proportion of abnormal acinar cells by 30%, and interstitial space by 40%. Therapeutic treatment with feG significantly reduced the AP-induced abnormal acinar cells by 10% and the interstitial space by 20%. Pancreatic ICAM-1 mRNA expression was upregulated in AP and was reduced by 50% with prophylactic and therapeutic treatment with feG. We conclude that feG ameliorates experimental AP acting at least in part by modulating ICAM-1 expression in the pancreas.

The role of inflammatory and parenchymal cells in acute pancreatitis

The infiltration of inflammatory cells into the pancreas is an early and central event in acute pancreatitis that promotes local injury and systemic complications of the disease. Recent research has yielded the important finding that resident cells of the pancreas (particularly acinar and pancreatic stellate cells) play a dynamic role in leukocyte attraction via secretion of chemokines and cytokines and expression of adhesion molecules. Significant progress has been made in recent years in our understanding of the role of leukocyte movement (adhesion to the blood vessel wall, transmigration through the blood vessel wall and infiltration into the parenchyma) in the pathophysiology of acute pancreatitis. This review discusses recent studies and describes the current state of knowledge in the field. It is clear that detailed elucidation of the numerous processes in the inflammatory cascade is an essential step towards the development of improved therapeutic strategies in acute pancreatitis. Studies to date suggest that combination therapy targeting different steps of the inflammatory cascade may be the treatment of choice for this disease.

Angiotensin II type 1 receptor-dependent nuclear factor-kappaB activation-mediated proinflammatory actions in a rat model of obstructive acute pancreatitis

Angiotensin II is a key mediator of inflammation, and nuclear factor-kappaB (NF-kappaB) plays a critical role in various inflammatory diseases, including acute pancreatitis (AP). This study sought to elucidate the mechanism mediating angiotensin II involvement in angiotensin II type 1 (AT1) receptor-mediated NF-kappaB activation, and ultimately in proinflammatory actions of AP pathogenesis. A rat model of obstructive pancreatitis was induced by ligation of the common biliopancreatic duct. Pancreatic injury was determined by assessing pancreatic histology, myeloperoxidase activity, and serum interleukin-6. Protein levels of pancreatic angiotensinogen and AT1 receptor as well as NF-kappaB inhibitory subunits (IkappaBalpha and IkappaBbeta) and phospho-NF-kappaB p65, kappaB-related proteins (intercellular adhesion molecule-1, cyclooxygenase-2, and interleukin-1), and NADPH oxidase isoforms p67 and p22 were examined by Western blot. Nuclear kappaB binding activity and degree of oxidative stress were determined by electrophoretic mobility shift assay and glutathione/nitrotyrosine examination, respectively. The effects of losartan, an AT1 receptor antagonist, on NF-kappaB-mediated proinflammatory actions were also assessed. Induction of AP was associated with a time-dependent increase in pancreatic angiotensinogen levels. AT1 receptor blockade with losartan improved the pancreatic histological damage, myeloperoxidase activity, and serum interleukin-6. Losartan treatment also reduced AP-associated depletion of IkappaBbeta and elevation of phospho-NF-kappaB p65 protein expression as well as the enhanced nuclear kappaB binding activity and elevated levels of kappaB-related proteins. In addition, losartan treatment suppressed pancreatic glutathione and nitrotyrosine levels, which were consistent with decreased NADPH oxidase expression. These data provide substantial evidence that angiotensin II is involved in AT1 receptor-mediated NADPH oxidase-dependent NF-kappaB activation; thus, it might ultimately promote proinflammatory actions during AP pathogenesis.

Therapeutic proteasome inhibition in experimental acute pancreatitis

AIM: To establish the therapeutic potential of proteasome inhibition, we examined the therapeutic effects of MG132 (Z-Leu-Leu-Leu-aldehyde) in an experimental model of acute pancreatitis.

METHODS: Pancreatitis was induced in rats by two hourly intraperitoneal (ip) injections of cholecystokinin octapeptide (CCK; 2 × 100 μg/kg) and the proteasome inhibitor MG132 (10 mg/kg ip) was administered 30 min after the second CCK injection. Animals were sacrificed 4 h after the first injection of CCK.

RESULTS: Administering the proteasome inhibitor MG132 (at a dose of 10 mg/kg, ip) 90 min after the onset of pancreatic inflammation induced the expression of cell-protective 72 kDa heat shock protein (HSP72) and decreased DNA-binding of nuclear factor-κB (NF-κB).

Furthermore MG132 treatment resulted in milder inflammatory response and cellular damage, as revealed by improved laboratory and histological parameters of pancreatitis and associated oxidative stress.

CONCLUSION: Our findings suggest that proteasome inhibition might be beneficial not only for the prevention, but also for the therapy of acute pancreatitis.

Constitutive IKK2 activation in acinar cells is sufficient to induce pancreatitis in vivo

Activation of the inhibitor of NF-kappaB kinase/NF-kappaB (IKK/NF-kappaB) system and expression of proinflammatory mediators are major events in acute pancreatitis. However, the in vivo consequences of IKK activation on the onset and progression of acute pancreatitis remain unclear. Therefore, we modulated IKK activity conditionally in pancreatic acinar cells. Transgenic mice expressing the reverse tetracycline-responsive transactivator (rtTA) gene under the control of the rat elastase promoter were generated to mediate acinar cell-specific expression of IKK2 alleles. Expression of dominant-negative IKK2 ameliorated cerulein-induced pancreatitis but did not affect activation of trypsin, an initial event in experimental pancreatitis. Notably, expression of constitutively active IKK2 was sufficient to induce acute pancreatitis. This acinar cell-specific phenotype included edema, cellular infiltrates, necrosis, and elevation of serum lipase levels as well as pancreatic fibrosis. IKK2 activation caused increased expression of known NF-kappaB target genes, including mediators of the inflammatory response such as TNF-alpha and ICAM-1. Indeed, inhibition of TNF-alpha activity identified this cytokine as an important effector of IKK2-induced pancreatitis. Our data identify the IKK/NF-kappaB pathway in acinar cells as being key to the development of experimental pancreatitis and the major factor in the inflammatory response typical of this disease.

Why does pancreatic overstimulation cause pancreatitis?

Many animal models are available to investigate the pathogenesis of pancreatitis, an inflammatory disorder of the pancreas. However, the secretagogue hyperstimulation model of pancreatitis is the most commonly used. Animals infused with high doses of cholecystokinin (CCK) exhibit hyperamylasemia, pancreatic edema, and acinar cell injury, which closely mimic pancreatitis in humans. Intra-acinar zymogen activation is an essential early event in the pathogenesis of secretagogue-induced pancreatitis. Early in the course of pancreatitis, lysosomal hydrolases colocalize with digestive zymogens and activate them. These activated zymogens then cause acinar cell injury and necrosis, a characteristic of pancreatitis. Besides being the site of initiation of injury in pancreatitis, acinar cells also synthesize and release cytokines and chemokines very early in the course of pancreatitis, which then attract and activate inflammatory cells and initiate the disease's systemic phase.

Pioglitazone attenuates the severity of sodium taurocholate-induced severe acute pancreatitis

AIM

To determine the effect of pioglitazone, a specific peroxisome proliferator-activated receptor-gamma (PPARgamma) ligand, on development of severe acute pancreatitis (SAP) and expression of nuclear factor-kappa B (NF-kappaB) and intercellular adhesion molecule-1 (ICAM-1) in the pancreas.

METHODS

Male Sprague-Dawley (SD) rats (160-200 g) were randomly allocated into three groups (n = 18 in each group): severe acute pancreatitis group, pioglitazone group, sham group. SAP was induced by retrograde infusion of 1 mL/kg body weight 5% sodium taurocholate (STC) into the biliopancreatic duct of male SD rats. Pioglitazone was injected intraperitoneally two hours piror to STC infusion. Blood and ascites were obtained for detecting amylase and ascitic capacity. Pancreatic wet/dry weight ratio, expression of NF-kappaB and ICAM-1 in pancreatic tissues were detected by immunohistochemical staining. Pancreatic tissue samples were stained with hematoxylin and eosin (HE) for routine optic microscopy.

RESULTS

Sham group displayed normal pancreatic structure. SAP group showed diffuse hemorrhage, necrosis and severe edema in focal areas of pancreas. There was obvious adipo-saponification in abdominal cavity. Characteristics such as pancreatic hemorrhage, necrosis, severe edema and adipo-saponification were found in pioglitazone group, but the levels of those injuries were lower in pioglitazone group than those in SAP group. The wet/dry pancreatic weight ratio, ascetic capacity, serum and ascitic activities of anylase in the SAP group were significantly higher than those in the sham group and pioglitazone group respectively (6969.50 +/- 1368.99 vs 2104.67 +/- 377.16, 3.99 +/- 1.22 vs 2.48 +/- 0.74, P < 0.01 or P < 0.05). According to Kusske criteria, the pancreatic histologic score showed that interstitial edema, inflammatory infiltration, parenchyma necrosis and parenchyma hommorrhage in SAP group significantly differed from those in the sham group and pioglitazone group (7.17 +/- 1.83 vs 0.50 +/- 0.55, 7.67 +/- 0.82 vs 6.83 +/- 0.75, P < 0.01, P < 0.05. The expression of NF-kappaB and ICAM-1 in sham group was lower than that in SAP group and pioglitazone group (0.50 +/- 0.55 vs 33 +/- 1.21, P < 0.01). There was a significant difference in the expression of NF-kappaB and ICAM-1 between SAP group and pioglitazone group (7.50 +/- 1.05 vs 11.33 +/- 1.75, 0.80 +/- 0.53 vs 1.36 +/- 0.54, P < 0.01 or P < 0.05) at 12 h after the induction of pancreatitis.

CONCLUSION

Pioglitazone attenuates the severity of SAP. The beneficial effect of pioglitazone is multifactorial due to its anti-inflammatory activities, most likely through the inhibition of ICAM-1 expression and NF-kappaB activation. Specific ligands of PPARgamma may represent the novel and effective means of clinical therapy for SAP.

Expression of mutated cationic trypsinogen reduces cellular viability in AR4-2J cells

Mutations in the human cationic trypsinogen are associated with hereditary pancreatitis. The cDNA coding for human cationic trypsinogen was subcloned into the expression vector pcDNA3. The mutations R122H, N29I, A16V, D22G, and K23R were introduced by site directed mutagenesis. We constructed an expression vector coding for active trypsin by subcloning the cDNA of trypsin lacking the coding region for the trypsin activating peptide behind an appropriate signal peptide. Expression of protein was verified by Western blot and measurement of enzymatic activity. AR4-2J cells were transiently transfected with the different expression vectors and cell viability and intracellular caspase-3 activity were quantified. In contrast to wild-type trypsinogen, expression of active trypsin and mutated trypsinogens reduced cell viability of AR4-2J cells. Expression of trypsin and R122H trypsinogen induced caspase-3 activity. Acinar cells might react to intracellular trypsin activity by triggering apoptosis.

Signal transduction in alcohol-related diseases

This article summarizes the proceedings of a symposium presented at the 12th World Congress on Biomedical Alcohol Research, organized by the International Society for Biomedical Research on Alcoholism, held at the University of Heidelberg in Mannheim, Germany, in September and October 2004. The organizers and chairpersons were Manfred V. Singer and Stephen J. Pandol. The presentations were (1) Ethanol‐induced acinar cell injury, by Minoti V. Apte; (2) Oxidants and antioxidants: signal transduction and alcohol, by Thomá Zima; (3) Anti–TGF‐β strategies for the treatment of chronic liver disease, by Steven Dooley; (4) Immune mechanisms in alcohol‐induced liver disease, by Sören V. Siegmund; and (5) Alcoholic pancreatitis: insights from animal models, by Steven J. Pandol.

Pathophysiology of acute pancreatitis

Acute pancreatitis is a common clinical condition. It is a disease of variable severity in which some patients experience mild, self-limited attacks while others manifest a severe, highly morbid, and frequently lethal attack. The exact mechanisms by which diverse etiological factors induce an attack are still unclear. It is generally believed that the earliest events in acute pancreatitis occur within acinar cells. Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction. If this inflammatory reaction is marked, it leads to a systemic inflammatory response syndrome (SIRS). An excessive SIRS leads to distant organ damage and multiple organ dysfunction syndrome (MODS). MODS associated with acute pancreatitis is the primary cause of morbidity and mortality in this condition. Recent studies have established the role played by inflammatory mediators in the pathogenesis of acute pancreatitis and the resultant MODS. At the same time, recent research has demonstrated the importance of acinar cell death in the form of apoptosis and necrosis as a determinant of pancreatitis severity. In this review, we will discuss about our current understanding of the pathophysiology of acute pancreatitis.

Inflammatory response on the pancreatic acinar cell injury

Acute pancreatitis is an inflammatory disorder, and inflammation not only affects the pathogenesis but also the course of the disease. Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction; if marked this leads to a systemic inflammatory response syndrome (SIRS). An excessive SIRS leads to distant organ damage and multiple organ dysfunction syndrome (MODS). MODS associated with acute pancreatitis is the primary cause of morbidity and mortality in this condition. Recent studies by us and other investigators have established the critical role played by inflammatory mediators such as TNF-alpha, IL-1beta, IL-6, IL-8, CINC/GRO-alpha, MCP-1, PAF, IL-10, CD40L, C5a, ICAM-1, MIP1-alpha, RANTES, substance P, and hydrogen sulfide in acute pancreatitis and the resultant MODS. This review intends to present an overview of the inflammatory response that takes place following pancreatic acinar cell injury.

Ethanol differentially regulates NF-kappaB activation in pancreatic acinar cells through calcium and protein kinase C pathways

Mechanisms of alcoholic pancreatitis remain unknown. Previously, we showed that ethanol feeding sensitizes rats to pancreatitis caused by CCK-8, at least in part, by augmenting activation of the proinflammatory transcription factor NF-kappaB. To elucidate the mechanism of sensitization, here we investigate the effect of ethanol on Ca(2+)- and PKC-mediated pathways of CCK-induced NF-kappaB activation using an in vitro system of rat pancreatic acini incubated with ethanol. Ethanol augmented CCK-8-induced activation of NF-kappaB, similar to our in vivo findings with ethanol-fed rats. In contrast, ethanol prevented NF-kappaB activation caused by thapsigargin, an agent that mobilizes intracellular Ca(2+) bypassing the receptor. Pharmacological analysis showed that NF-kappaB activation by thapsigargin but not by CCK-8 is mediated through the calcineurin pathway and that the inhibitory effect of ethanol on the thapsigargin-induced NF-kappaB activation could be through inhibiting this pathway. Ethanol augmented NF-kappaB activation induced by the phorbol ester PMA, a direct activator of PKC. Inhibitory analysis demonstrated that Ca(2+)-independent (novel and/or atypical) PKC isoforms are involved in NF-kappaB activation induced by both CCK-8 and PMA in cells treated and not treated with ethanol. The results indicate that ethanol differentially affects the Ca(2+)/calcineurin- and PKC-mediated pathways of NF-kappaB activation in pancreatic acinar cells. These effects may play a role in the ability of ethanol to sensitize pancreas to the inflammatory response and pancreatitis.

Phosphatidylinositide 3-kinase gamma regulates key pathologic responses to cholecystokinin in pancreatic acinar cells

BACKGROUND & AIMS

Early events in the pancreatic acinar cell critical for development of pancreatitis include activation of the transcription factor nuclear factor kappa B (NF-kappa B), abnormal Ca(2+) responses, and trypsinogen activation. Mechanisms underlying these responses, which can be studied in isolated pancreatic acini stimulated with supraphysiologic doses of cholecystokinin (CCK-8), remain poorly understood. We here report that these responses are regulated by phosphatidylinositide 3-kinase (PI3K) gamma.

METHODS

To inactivate PI3K, we used mice deficient in the catalytic PI3K gamma subunit p110 gamma as well as the PI3K inhibitors LY294002 and wortmannin. We measured Ca(2+) responses by using Fura-2, NF-kappa B-binding activity by electromobility shift assay, I kappa B degradation by Western blotting, and trypsinogen activation by fluorogenic assay.

RESULTS

CCK-induced intracellular Ca(2+) mobilization, Ca(2+) influx, trypsinogen, and NF-kappa B activation were all diminished in pancreatic acini isolated from p110 gamma(-/-) mice. Both in mouse and rat acini, these responses were inhibited by the PI3K inhibitors. The Ca(2+) signal and trypsinogen activation were similarly reduced in acini isolated from p110 gamma(-/-) and p110 gamma(+/-) mice compared with wild-type mice. By contrast, NF-kappa B activation was inhibited in p110 gamma(-/-) acini but not in p110 gamma(+/-) acini. These differences indicate that the mechanism of NF-kappa B regulation by PI3K gamma differs from those for the Ca(2+) and trypsinogen responses. CCK-induced responses in p110 gamma(-/-) acini were all further inhibited by LY294002, indicating the involvement of other PI3K isoform(s), in addition to PI3K gamma.

CONCLUSIONS

The results show that key pathologic responses of the pancreatic acinar cell are regulated by PI3K gamma and suggest an important role for this PI3K isoform in pancreatitis.

Animal and in vitro models of alcoholic pancreatitis: role of cholecystokinin

Although ethanol abuse is the major etiologic factor in the development of acute and chronic pancreatitis, the mechanisms of ethanol effects to cause pancreatitis are poorly understood. The major reason for the lack of progress is the relative lack of animal models that reproduce the deleterious effects of ethanol on the pancreas that are observed in human disease. We propose that the effect of ethanol on the pancreas is due to its ability to sensitize animals and humans to the potentially injurious effects of other stimuli. We have developed models of ethanol-induced acute and chronic pancreatitis in rats as well as pancreatic acinar cells in primary culture demonstrating that ethanol sensitizes the pancreas to the inflammatory, cell death, and fibrosing responses caused by cholecystokinin (CCK). Our results indicate that the ethanol-sensitized inflammatory response is the key or trigger event for the development of the other pathologic responses in both acute and chronic pancreatitis, such as cell death, intracellular digestive enzyme activation, and fibrosis. These findings suggest that experimental strategies designed to reveal the modulating effects of ethanol on the mechanisms underlying the inflammatory, cell death, and fibrosing responses stimulated by CCK will provide the key information needed to understand how ethanol abuse causes pancreatitis.

The PPARgamma ligand, 15d-PGJ2, attenuates the severity of cerulein-induced acute pancreatitis

INTRODUCTION

The prostaglandin D2 metabolite, 15d-PGJ2, a potent natural ligand for peroxisome proliferator-activated receptor gamma (PPARgamma), exerts antiinflammatory effects by inhibiting the induction of inflammatory response genes and NF-kappaB-dependent transcription. AIM To determine whether 15d-PGJ2 decreases the severity of secretagogue-induced acute pancreatitis (AP) and to assess cellular mechanisms contributing to these effects. METHODOLOGY Swiss Webster mice were injected with either saline or cerulein (50 microg/kg) hourly for 8 hours and received either 15d-PGJ2 (2 mg/kg) or vehicle 1 hour before and 4 hours after induction of AP. RESULTS Treatment with 15d-PGJ2 significantly attenuated AP, as determined by histologic assessment of edema, vacuolization, inflammation, and necrosis. This attenuation was associated with decreased cyclooxygenase-2 (COX-2) and intercellular adhesion molecule-1 (ICAM-1) expression and decreased serum and pancreatic IL-6 levels. Treatment with 15d-PGJ2 markedly inhibited NF-kappaB DNA-binding activity, and, moreover, this decreased activity was associated with a concomitant inhibition of IkappaB protein degradation. CONCLUSION Our findings demonstrate that 15d-PGJ2 attenuates the severity of AP most likely through the inhibition of COX-2 expression, IL-6 production, and NF-kappaB activation. Ligands specific for PPARgamma may represent novel and effective means of clinical therapy for AP.