Signal transduction, calcium and acute pancreatitis

Pacing intracellular Ca2+ signals in exocrine acinar cells

An increase in intracellular [Ca2+ ] in exocrine acinar cells resident in the salivary glands or pancreas is a fundamental event that drives fluid secretion and exocytosis of proteins. Stimulation with secretagogues initiates Ca2+ signals with precise spatiotemporal properties thought to be important for driving physiological output. Both in vitro, in acutely isolated acini, and in vivo, in animals expressing genetically encoded indicators, individual cells appear specialized to initiate Ca2+ signals upon stimulation. Furthermore, these signals appear to spread to neighbouring cells. These properties are present in the absence of a conventional pacemaker mechanism dependent on the cyclical activation of Ca2+ -dependent or Ca2+ -conducting plasma membrane ion channels. In this article, we propose a model for 'pacing' intracellular Ca2+ signals in acinar cells based on the enhanced sensitivity of a subpopulation of individual cells and the intercellular diffusion through gap junctions of inositol 1,4,5-trisphosphate and Ca2+ to neighbouring cells.

Neither too much nor too little: mitochondrial calcium concentration as a balance between physiological and pathological conditions

Ca2+ ions serve as pleiotropic second messengers in the cell, regulating several cellular processes. Mitochondria play a fundamental role in Ca2+ homeostasis since mitochondrial Ca2+ (mitCa2+) is a key regulator of oxidative metabolism and cell death. MitCa2+ uptake is mediated by the mitochondrial Ca2+ uniporter complex (MCUc) localized in the inner mitochondrial membrane (IMM). MitCa2+ uptake stimulates the activity of three key enzymes of the Krebs cycle, thereby modulating ATP production and promoting oxidative metabolism. As Paracelsus stated, "Dosis sola facit venenum,"in pathological conditions, mitCa2+ overload triggers the opening of the mitochondrial permeability transition pore (mPTP), enabling the release of apoptotic factors and ultimately leading to cell death. Excessive mitCa2+ accumulation is also associated with a pathological increase of reactive oxygen species (ROS). In this article, we review the precise regulation and the effectors of mitCa2+ in physiopathological processes.

Pancreatitis in RYR1-related disorders

Mutations in RYR1 encoding the ryanodine receptor (RyR) skeletal muscle isoform (RyR1) are a common cause of inherited neuromuscular disorders. Despite its expression in a wide range of tissues, non-skeletal muscle manifestations associated with RYR1 mutations have only been rarely reported. Here, we report three patients with a diagnosis of Central Core Disease (CCD), King-Denborough Syndrome (KDS) and Malignant Hyperthermia Susceptibility (MHS), respectively, who in addition to their (putative) RYR1-related disorder also developed symptoms and signs of acute pancreatitis. In two patients, episodes were recurrent, with severe multisystem involvement and sequelae. RyR1-mediated calcium signalling plays an important role in normal pancreatic function but has also been critically implicated in the pathophysiology of acute pancreatitis, particularly in bile acid- and ethanol-induced forms. Findings from relevant animal models indicate that pancreatic damage in these conditions may be ameliorated through administration of the specific RyR1 antagonist dantrolene and other compounds modifying pancreatic metabolism including calcium signalling. These observations suggest that patients with RYR1 gain-of-function variants may be at increased risk of developing acute pancreatitis, a condition which should therefore be considered in the health surveillance of such individuals.

Establishment and Validation of a Nomogram Prediction Model for the Severe Acute Pancreatitis

Background

Severe acute pancreatitis (SAP) can progress to lung and kidney dysfunction, and blood clotting within 48 hours of its onset, and is associated with a high mortality rate. The aim of this study was to establish a reliable diagnostic prediction model for the early stage of severe pancreatitis.

Methods

The clinical data of patients diagnosed with acute pancreatitis from October 2017 to June 2022 at the Shangluo Central Hospital were collected. The risk factors were screened by least absolute shrinkage and selection operator (LASSO) regression analysis. A novel nomogram model was then established by multivariable logistic regression analysis.

Results

The data of 436 patients with acute pancreatitis, 45 (10.3%) patients had progressed to SAP. Through univariate and LASSO regression analyses, the neutrophils (P <0.001), albumin (P < 0.001), blood glucose (P < 0.001), serum calcium (P < 0.001), serum creatinine (P < 0.001), blood urea nitrogen (P < 0.001) and procalcitonin (P = 0.005) were identified as independent predictive factors for SAP. The nomogram built on the basis of these factors predicted SAP with sensitivity of 0.733, specificity of 0.9, positive predictive value of 0.458 and negative predictive value of 0.967. Furthermore, the concordance index of the nomogram reached 0.889 (95% CI, 0.837-0.941), and the area under the curve (AUC) in receiver operating characteristic curve (ROC) analysis was significantly higher than that of the APACHEII and ABISAP scoring systems. The established model was validated by plotting the clinical decision curve analysis (DCA) and clinical impact curve (CIC).

Conclusion

We established a nomogram to predict the progression of early acute pancreatitis to SAP with high discrimination and accuracy.

REL-NPMI: Exploring genotype and phenotype relationship of pancreatitis based on improved normalized point-by-point mutual information

Pancreatitis is a relatively serious disease caused by the self-digestion of trypsin in the pancreas. The generation of diseases is closely related to gene and phenotype information. Generally, gene-phenotype relations are mainly obtained through clinical experiments, but the cost is huge. With the amount of published biomedical literature increasing exponentially, it carries a wealth of disease-related gene and phenotype information. This study provided an effective way to obtain disease-related gene and phenotype information. To our best knowledge, this work first attempted to explore relationships between genotype and phenotype about the pancreatitis from the computational perspective. It mined 6152 genes and 76,753 pairs of genotype and phenotype extracted from the biomedical literature about pancreatitis using text mining. Based on the above 76,753 pairs, the study proposed an improved normalized point-wise mutual information (REL-NPMI) model to optimize gene-phenotype relations related to pancreatitis, and obtained 12,562 gene-phenotype pairs which may be related to pancreatitis. The extracted top 20 results were validated and evaluated. The experimental results show that the method is promising for exploring pancreatitis' molecular mechanism, thus it provides a computational way for studying pancreatitis' disease pathogenesis. Data resources and the Pancreatitis Gene-Phenotype Association Database are available at http://114.116.4.45:8081/and resources are also available at https://github.com/polipoptbe8023/REL-NPMI.git.

Primary hyperparathyroidism presenting as acute pancreatitis: An institutional experience with review of the literature

BACKGROUND

Acute pancreatitis (AP) presenting as an initial manifestation of primary hyperparathyroidism (PHPT) is uncommon, and its timely diagnosis is crucial in preventing recurrent attacks of pancreatitis.

AIM

To determine the clinical, biochemical, and radiological profile of PHPT patients presenting as AP.

METHODS

This is a retrospective observational study, 51 consecutive patients admitted with the diagnosis of PHPT during January 2010 and October 2021 at a tertiary care hospital in Puducherry, India was included. The diagnosis of AP was established in the presence of at least two of the three following features: abdominal pain, levels of serum amylase or lipase greater than three times the normal, and characteristic features at abdominal imaging.

RESULTS

Out of the 51 consecutive patients with PHPT, twelve (23.52%) had pancreatitis [5 (9.80%) AP, seven (13.72%) chronic pancreatitis (CP)]. PHPT with AP (PHPT-AP) was more common among males with the presentation at a younger age (35.20 ± 16.11 vs 49.23 ± 14.80 years, P = 0.05) and lower plasma intact parathyroid hormone (iPTH) levels [125 (80.55-178.65) vs 519.80 (149-1649.55, P = 0.01)] compared to PHPT without pancreatitis (PHPT-NP). The mean serum calcium levels were similar in both PHPT-AP and PHPT-NP groups [(11.66 ± 1.15 mg/dL) vs (12.46 ± 1.71 mg/dL), P = 0.32]. PHPT-AP also presented with more gastrointestinal symptoms like abdominal pain, nausea, and vomiting with lesser skeletal and renal manifestations as compared to patients with PHPT-NP.

CONCLUSION

AP can be the only presenting feature of PHPT. Normal or higher serum calcium levels during AP should always draw attention towards endocrine causes like PHPT.

PREVALENCE OF SPINK 1 AND CASR GENE MUTATIONS IN ACUTE AND RECURRENT ACUTE PANCREATITIS : A STUDY FROM CENTRAL INDIA

Background: Genetic factors may play an important role in the pathogenesis of acute pancreatitis. It has been observed in various studies that the presence of risk factors alone like alcohol abuse or gall bladder stones does not lead to attacks of pancreatitis in all the patients. This leads to assumption that genetic factors may decrease the threshold for the development of pancreatitis in presence of one or more risk factors. We observed that there is a paucity of data regarding the role of genetics in acute pancreatitis (AP) and recurrent acute pancreatitis (RAP) in our part of the world and we aimed at studying the prevalence of genetic mutations in such patients. Methods: Our study intended to nd the prevalence of SPINK1 N34S (Serine protease inhibitor kazal type 1) and CaSR (Calcium sensing receptor) gene mutations in patients of AP and RAP. A total of 50 patients and 25 age and gender matched controls entered our study. Blood samples were obtained from all the cases and controls for routine investigations and genetic analysis. SPINK 1 N34S and CaSR gene mutation studies were done in all the patients and controls. Results: Alcohol (64%) followed by gallbladder stone disease (20%) was the most common aetiology of pancreatitis. SPINK 1 N34S mutation was present in 21 patients and 2 controls whereas CaSR gene mutation was present in 13 patients and 2 controls. Patients with SPINK 1 N34S and CaSR gene mutations were younger than the patients without these mutations. Prevalence of both SPINK1 N34S and CaSR gene mutations was higher in patients of RAP than AP. These mutations were not associated with aetiology or severity of pancreatitis. Conclusion: The prevalence SPINK 1 N34S and CaSR gene mutations was higher in patients of AP and RAP. Identication of these mutations in patients of AP can help in the identication of patients who are at increased risk of recurrent attacks of AP

Imaging Mitochondrial Functions: from Fluorescent Dyes to Genetically-Encoded Sensors

Mitochondria are multifunctional organelles that are crucial to cell homeostasis. They constitute the major site of energy production for the cell, they are key players in signalling pathways using secondary messengers such as calcium, and they are involved in cell death and redox balance paradigms. Mitochondria quickly adapt their dynamics and biogenesis rates to meet the varying energy demands of the cells, both in normal and in pathological conditions. Therefore, understanding simultaneous changes in mitochondrial functions is crucial in developing mitochondria-based therapy options for complex pathological conditions such as cancer, neurological disorders, and metabolic syndromes. To this end, fluorescence microscopy coupled to live imaging represents a promising strategy to track these changes in real time. In this review, we will first describe the commonly available tools to follow three key mitochondrial functions using fluorescence microscopy: Calcium signalling, mitochondrial dynamics, and mitophagy. Then, we will focus on how the development of genetically-encoded fluorescent sensors became a milestone for the understanding of these mitochondrial functions. In particular, we will show how these tools allowed researchers to address several biochemical activities in living cells, and with high spatiotemporal resolution. With the ultimate goal of tracking multiple mitochondrial functions simultaneously, we will conclude by presenting future perspectives for the development of novel genetically-encoded fluorescent biosensors.

Early Intra-Acinar Events in Pathogenesis of Pancreatitis

Premature activation of digestive enzymes in the pancreas has been linked to development of pancreatitis for more than a century. Recent development of novel models to study the role of pathologic enzyme activation has led to advances in our understanding of the mechanisms of pancreatic injury. Colocalization of zymogen and lysosomal fraction occurs early after pancreatitis-causing stimulus. Cathepsin B activates trypsinogen in these colocalized organelles. Active trypsin increases permeability of these organelles resulting in leakage of cathepsin B into the cytosol leading to acinar cell death. Although trypsin-mediated cell death leads to pancreatic injury in early stages of pancreatitis, multiple parallel mechanisms, including activation of inflammatory cascades, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction in the acinar cells are now recognized to be important in driving the profound systemic inflammatory response and extensive pancreatic injury seen in acute pancreatitis. Chymotrypsin, another acinar protease, has recently been shown be play critical role in clearance of pathologically activated trypsin protecting against pancreatic injury. Mutations in trypsin and other genes thought to be associated with pathologic enzyme activation (such as serine protease inhibitor 1) have been found in familial forms of pancreatitis. Sustained intra-acinar activation of nuclear factor κB pathway seems to be key pathogenic mechanism in chronic pancreatitis. Better understanding of these mechanisms will hopefully allow us to improve treatment strategies in acute and chronic pancreatitis.

Inhibition of PAK1 alleviates cerulein-induced acute pancreatitis via p38 and NF-κB pathways

Acute pancreatitis is a life-threatening disease accompanied by systemic inflammatory response. NF-κB and p38 signal pathways are activated in AP induced by cerulein. And PAKs are multifunctional effectors of Rho GTPases with kinase activity. In the present study, the function of P21-activated kinase 1 (PAK1) in AP was investigated, and found that PAK1 was up-regulated in pancreas of AP mice model, and led to NF-κB and p38 pathway activation. PAK1 inhibition by shRNA or small molecule inhibitor FRAX597 decreased NF-κB and p38 activity, also alleviated the pathological damage in the pancreas of AP mice model, including decreasing the amylase and lipase levels in serum, decreasing the levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β in AP. These results suggested that PAK1 inhibition protects against AP by inhibiting NF-κB and p38 pathways, and indicated that PAK1 is a potential therapy to alleviate AP patients in clinic, and these need to be explored further.

Dihydrodiosgenin protects against experimental acute pancreatitis and associated lung injury through mitochondrial protection and PI3Kγ/Akt inhibition

BACKGROUND AND PURPOSE

Acute pancreatitis (AP) is a painful and distressing disorder of the exocrine pancreas with no specific treatment. Diosgenyl saponins extracted from from Dioscorea zingiberensis C. H. Wright have been reported to protect against experimental models of AP. Diosgenin, or its derivatives are anti-inflammatory in various conditions. However, the effects of diosgenin and its spiroacetal ring opened analogue, dihydrodiosgenin (Dydio), on AP have not been determined.

EXPERIMENTAL APPROACH

Effects of diosgenin and Dydio on sodium taurocholate hydrate (Tauro)-induced necrosis were tested, using freshly isolated murine pancreatic acinar cells. Effects of Dydio on mitochondrial dysfunction in response to Tauro, cholecystokinin-8 and palmitoleic acid ethyl ester were also assessed. Dydio (5 or 10 mg·kg^-1 ) was administered after the induction in vivo of Tauro-induced AP (Wistar rats), caerulein-induced AP and palmitoleic acid plus ethanol-induced AP (Balb/c mice). Pancreatitis was assessed biochemically and histologically. Activation of pancreatic PI3Kγ/Akt was measured by immunoblotting.

KEY RESULTS

Dydio inhibited Tauro-induced activation of the necrotic cell death pathway and prevented pancreatitis stimuli-induced mitochondrial dysfunction. Therapeutic administration of Dydio ameliorated biochemical and histopathological responses in all three models of AP through pancreatic mitochondrial protection and PI3Kγ/Akt inactivation. Moreover, Dydio improved pancreatitis-associated acute lung injury through preventing excessive inflammatory responses.

CONCLUSION AND IMPLICATIONS

These data provide in vitro and in vivo mechanistic evidence that the diosgenin analogue, Dydio could be potential treatment for AP. Further medicinal optimization of diosgenin and its analogue might be a useful strategy for identifying lead candidates for inflammatory diseases.

Hydrogen peroxide attenuates refilling of intracellular calcium store in mouse pancreatic acinar cells

Intracellular calcium (Ca²⁺) oscillation is an initial event in digestive enzyme secretion of pancreatic acinar cells. Reactive oxygen species are known to be associated with a variety of oxidative stress-induced cellular disorders including pancreatitis. In this study, we investigated the effect of hydrogen peroxide (H₂O₂) on intracellular Ca²⁺ accumulation in mouse pancreatic acinar cells. Perfusion of H₂O₂ at 300 µM resulted in additional elevation of intracellular Ca²⁺ levels and termination of oscillatory Ca²⁺ signals induced by carbamylcholine (CCh) in the presence of normal extracellular Ca²⁺. Antioxidants, catalase or DTT, completely prevented H₂O₂-induced additional Ca²⁺ increase and termination of Ca²⁺ oscillation. In Ca²⁺-free medium, H₂O₂ still enhanced CCh-induced intracellular Ca²⁺ levels and thapsigargin (TG) mimicked H₂O₂-induced cytosolic Ca²⁺ increase. Furthermore, H₂O₂-induced elevation of intracellular Ca²⁺ levels was abolished under sarco/endoplasmic reticulum Ca²⁺ ATPase-inactivated condition by TG pretreatment with CCh. H₂O₂ at 300 µM failed to affect store-operated Ca²⁺ entry or Ca²⁺ extrusion through plasma membrane. Additionally, ruthenium red, a mitochondrial Ca²⁺ uniporter blocker, failed to attenuate H₂O₂-induced intracellular Ca²⁺ elevation. These results provide evidence that excessive generation of H₂O₂ in pathological conditions could accumulate intracellular Ca²⁺ by attenuating refilling of internal Ca²⁺ stores rather than by inhibiting Ca²⁺ extrusion to extracellular fluid or enhancing Ca²⁺ mobilization from extracellular medium in mouse pancreatic acinar cells.

Insights into the genetic risk factors for the development of pancreatic disease

Diseases of the exocrine pancreas such as recurrent acute pancreatitis (RAP), chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC) represent syndromes defined according to traditional clinicopathologic criteria. The failure of traditional approaches to identify primary mechanisms underlying these progressive disorders illustrates a greater problem of failure of the germ theory of disease for complex disorders. Multiple genetic discoveries and new complex disease models force consideration of a new paradigm of 'precision medicine', requiring a new mechanistic definition of CP. Recognizing the advances in understanding complex gene and environment interactions, as well as the development of new strategies that limit or prevent the development of devastating end-stage diseases of the pancreas may lead to substantial improvements in patient care.

Pathophysiological mechanisms in acute pancreatitis: Current understanding

The precise mechanisms involved in the pathophysiology of acute pancreatitis (AP) are still far from clear. Several earlier studies have focused mainly on pancreatic enzyme activation as the key intracellular perturbation in the pancreatic acinar cells. For decades, the trypsin-centered hypothesis has remained the focus of the intra-acinar events in acute pancreatitis. Recent advances in basic science research have lead to the better understanding of various other mechanisms such as oxidative and endoplasmic stress, impaired autophagy, mitochondrial dysfunction, etc. in causing acinar cell injury. Despite all efforts, the clinical outcome of patients with AP has not changed significantly over the years. This suggests that the knowledge of the critical molecular pathways in the pathophysiology of AP is still limited. The mechanisms through which the acinar cell injury leads to local and systemic inflammation are not well understood. The role of inflammatory markers and immune system activation is an area of much relevance from the point of view of finding a target for therapeutic intervention. Some data are available from experimental animal models but not much is known in human pancreatitis. This review intends to highlight the current understanding in this area.

The role of Ca2+ influx in endocytic vacuole formation in pancreatic acinar cells

The inducers of acute pancreatitis trigger a prolonged increase in the cytosolic Ca(2+) concentration ([Ca(2+)]c), which is responsible for the damage to and eventual death of pancreatic acinar cells. Vacuolization is an important indicator of pancreatic acinar cell damage. Furthermore, activation of trypsinogen occurs in the endocytic vacuoles; therefore the vacuoles can be considered as 'initiating' organelles in the development of the cell injury. In the present study, we investigated the relationship between the formation of endocytic vacuoles and Ca(2+) influx developed in response to the inducers of acute pancreatitis [bile acid taurolithocholic acid 3-sulfate (TLC-S) and supramaximal concentration of cholecystokinin-8 (CCK)]. We found that the inhibitor of STIM (stromal interaction molecule)/Orai channels, GSK-7975A, effectively suppressed both the Ca(2+) influx (stimulated by inducers of pancreatitis) and the formation of endocytic vacuoles. Cell death induced by TLC-S or CCK was also inhibited by GSK-7975A. We documented the formation of endocytic vacuoles in response to store-operated Ca(2+) entry (SOCE) induced by thapsigargin [TG; inhibitor of sarcoplasmic/endoplasmic reticulum (ER) Ca(2+) pumps] and observed strong inhibition of TG-induced vacuole formation by GSK-7975A. Finally, we found that structurally-unrelated inhibitors of calpain suppress formation of endocytic vacuoles, suggesting that this Ca2+-dependent protease is a mediator between Ca(2+) elevation and endocytic vacuole formation.

Pharmacologic therapy for acute pancreatitis

While conservative management such as fluid, bowel rest, and antibiotics is the mainstay of current acute pancreatitis management, there is a lot of promise in pharmacologic therapies that target various aspects of the pathogenesis of pancreatitis. Extensive review of preclinical studies, which include assessment of therapies such as anti-secretory agents, protease inhibitors, anti-inflammatory agents, and anti-oxidants are discussed. Many of these studies have shown therapeutic benefit and improved survival in experimental models. Based on available preclinical studies, we discuss potential novel targeted pharmacologic approaches that may offer promise in the treatment of acute pancreatitis. To date a variety of clinical studies have assessed the translational potential of animal model effective experimental therapies and have shown either failure or mixed results in human studies. Despite these discouraging clinical studies, there is a great clinical need and there exist several preclinical effective therapies that await investigation in patients. Better understanding of acute pancreatitis pathophysiology and lessons learned from past clinical studies are likely to offer a great foundation upon which to expand future therapies in acute pancreatitis.

Chemopreventive effects of resveratrol in a rat model of cerulein-induced acute pancreatitis

In the past decades, a greater understanding of acute pancreatitis has led to improvement in mortality rates. Nevertheless, this disease continues to be a health care system problem due to its economical costs. Future strategies such as antioxidant supplementation could be very promising, regarding to beginning and progression of the disease. For this reason, this study was aimed at assessing the effect of exogenous administration of resveratrol during the induction process of acute pancreatitis caused by the cholecystokinin analog cerulein in rats. Resveratrol pretreatment reduced histological damage induced by cerulein treatment, as well as hyperamylasemia and hyperlipidemia. Altered levels of corticosterone, total antioxidant status, and glutathione peroxidase were significantly reverted to control levels by the administration of resveratrol. Lipid peroxidation was also counteracted; nevertheless, superoxide dismutase enzyme was overexpressed due to resveratrol pretreatment. Related to immune response, resveratrol pretreatment reduced pro-inflammatory cytokine IL-1β levels and increased anti-inflammatory cytokine IL-10 levels. In addition, pretreatment with resveratrol in cerulein-induced pancreatitis rats was able to reverse, at least partially, the abnormal calcium signal induced by treatment with cerulein. In conclusion, this study confirms antioxidant and immunomodulatory properties of resveratrol as chemopreventive in cerulein-induced acute pancreatitis.

Genetic risk factors for pancreatic disorders

A combination of genetic, environmental, and metabolic factors contribute to the development and recurrence of acute and chronic pancreatitis; information on all of these is required to manage patients effectively. For example, variants that affect regulation of the protease, serine (PRSS)1-PRSS2, and claudin (CLDN)2 loci, rather than their coding sequences, interact with other genetic and environmental factors to affect disease development. New strategies are needed to use these data and determine their contribution to pathogenesis, because these variants differ from previously studied, rare variants in exons (coding regions) of genes such as PRSS1, SPINK1, cystic fibrosis transmembrane conductance regulator (CFTR), chymotrypsin (CTR)C, and calcium-sensing receptor (CASR). Learning how various genetic factors affect pancreatic cells and systems could lead to etiology-based therapies rather than treatment of symptoms.

The association of primary hyperparathyroidism with pancreatitis

The association between primary hyperparathyroidism (PHPT) and acute or chronic pancreatitis is controversial. For this reason, we conducted a review of the literature over the past 30 years to explore the relationship between these 2 disorders. Ten retrospective studies each with >50 patients diagnosed with PHPT were identified. With the notable exception of 2 studies, the rate of pancreatitis among patients with PHPT was higher than that reported in general among hospitalized patients without PHPT. A higher serum calcium level may contribute to pancreatitis in these cases, along with additional genetic or environmental insults. Hypercalcemia may predispose the pancreatic acinar cell to abnormal, sustained calcium levels, lead to premature pancreatic protease activation, and pancreatitis. Although there was only short-term follow-up, most reports cited that definitive treatment of PHPT by parathyroidectomy led to the resolution of pancreatitis attacks. The published cohorts of patients with PHPT and pancreatitis are subject to bias, because serum calcium screening was not universally performed among all control nonpancreatitis patients to evaluate for PHPT. However, the pooled clinical and experimental data suggest an association between PHPT and pancreatitis and implicate hypercalcemia. For clinicians, it is important to recognize pancreatitis in patients with PHPT and, conversely, to consider PHPT by checking serum calcium levels in patients, who present with an unexplained pancreatitis.

Mitochondria as sensors and regulators of calcium signalling

During the past two decades calcium (Ca(2+)) accumulation in energized mitochondria has emerged as a biological process of utmost physiological relevance. Mitochondrial Ca(2+) uptake was shown to control intracellular Ca(2+) signalling, cell metabolism, cell survival and other cell-type specific functions by buffering cytosolic Ca(2+) levels and regulating mitochondrial effectors. Recently, the identity of mitochondrial Ca(2+) transporters has been revealed, opening new perspectives for investigation and molecular intervention.

Long-lasting effect of infant rats endotoxemia on heat shock protein 60 in the pancreatic acinar cells: involvement of toll-like receptor 4

Introduction. Lipopolysaccharide endotoxin (LPS) is responsible for septic shock and multiorgan failure, but pretreatment of rats with low doses of LPS reduced pancreatic acute damage. Aim. We investigated the effects of the endotoxemia induced in the early period of life on Toll-like receptor 4 (TLR4), heat shock protein 60 (HSP60) and proapoptotic Bax, caspase-9 and -3 or antiapoptotic Bcl-2 protein expression in the pancreatic acinar cells of adult animals. Material and Methods. Newborn rats (25 g) were injected with endotoxin (Escherichia coli) for 5 consecutive days. Two months later, pancreatic acinar cells were isolated from all groups of animals and subjected to caerulein stimulation (10⁻⁸ M). Protein expression was assessed employing Western blot. For detection of apoptosis we have employed DNA fragmentation ladder assay. Results. Preconditioning of newborn rats with LPS increased TLR4, Caspase-9 and -3 levels, but failed to affect basal expression of HSP60, Bax, and Bcl-2. Subsequent caerulein stimulation increased TLR4, Bcl-2, and caspases, but diminished HSP60 and Bax proteins in pancreatic acinar cells. Endotoxemia dose-dependently increased TLR4, Bax, HSP60, and both caspases protein signals in the pancreatic acini, further inhibiting antiapoptotic Bcl-2. Conclusions. Endotoxemia promoted the induction of HSP60 via TLR4 in the infant rats and participated in the LPS-dependent pancreatic tissue protection against acute damage.

ADP-ribosylation factor 1 protein regulates trypsinogen activation via organellar trafficking of procathepsin B protein and autophagic maturation in acute pancreatitis

Several studies have suggested that autophagy might play a deleterious role in acute pancreatitis via intra-acinar activation of digestive enzymes. The prototype for this phenomenon is cathepsin B-mediated trypsin generation. To determine the organellar basis of this process, we investigated the subcellular distribution of the cathepsin B precursor, procathepsin B. We found that procathepsin B is enriched in Golgi-containing microsomes, suggesting a role for the ADP-ribosylation (ARF)-dependent trafficking of cathepsin B. Indeed, caerulein treatment increased processing of procathepsin B, whereas a known ARF inhibitor brefeldin A (BFA) prevented this. Similar treatment did not affect processing of procathepsin L. BFA-mediated ARF1 inhibition resulted in reduced cathepsin B activity and consequently reduced trypsinogen activation. However, formation of light chain 3 (LC3-II) was not affected, suggesting that BFA did not prevent autophagy induction. Instead, sucrose density gradient centrifugation and electron microscopy showed that BFA arrested caerulein-induced autophagosomal maturation. Therefore, ARF1-dependent trafficking of procathepsin B and the maturation of autophagosomes results in cathepsin B-mediated trypsinogen activation induced by caerulein.

Mitochondrial calcium in the life and death of exocrine secretory cells

The remarkable recent discoveries of the proteins mediating mitochondrial Ca(2+) transport (reviewed in this issue) provide an exciting opportunity to utilise this new knowledge to improve our fundamental understanding of relationships between Ca(2+) signalling and bioenergetics and, importantly, to improve the understanding of diseases in which Ca(2+) toxicity and mitochondrial malfunction play a crucial role. Ca(2+) is an important activator of exocrine secretion, a regulator of the bioenergetics of exocrine cells and a contributor to exocrine cell damage. Exocrine secretory cells, exocrine tissues and diseases affecting exocrine glands (like Sjögren's syndrome and acute pancreatitis) will, therefore, provide worthy research areas for the application of this new knowledge of the Ca(2+) transport mechanisms in mitochondria.

Serum lipid and fatty acid profiles are highly changed in patients with alcohol induced acute pancreatitis

BACKGROUND/AIMS

Hyperlipidemia is one known etiology of acute pancreatitis. Alcohol use is known to induce changes in lipid metabolism and might alter the serum lipid and fatty acid profile. We hypothesized that these changes may explain individual susceptibility of developing acute pancreatitis. We compared lipid and fatty acid profiles of patients with acute alcoholic pancreatitis and alcoholic controls.

METHODS

19 patients with their first alcoholic pancreatitis and 20 controls were included. Late follow-up samples were obtained from 16 patients. Serum lipids were analyzed enzymatically and the fatty acid profile using gas chromatography.

RESULTS

The concentrations of serum total cholesterol, LDL-cholesterol and HDL-cholesterol were markedly lower in patients than in controls during the acute disease but normalized after follow-up. Patients had statistically significantly lower fatty acid proportions of saturated C14:0, polyunsaturated C18:2, C18:3 and C20:3 of the n-6-series and C18:3 of the n-3-series than controls. In contrast, patients had higher percentages of saturated C16:0 and monounsaturated C18:1n9 fatty acids than controls. Mead acid, C20:3n9, marker of essential fatty acid deficiency, was lower in patients than in controls. C14:0, C20:3n6, C18:3n3 and C20:3n9 remained altered after follow-up.

CONCLUSION

Serum lipid and fatty acid levels were significantly altered during the acute disease and returned toward normal after 18-24 months, suggesting that the changes are secondary to acute pancreatitis. They are unlikely to be the much sought 'trigger factor' of pancreatic necro-inflammation. However, further studies are warranted to fully establish this point.

Effect of type of alcoholic beverage in causing acute pancreatitis

Background

The effect of different alcoholic beverages and drinking behaviour on the risk of acute pancreatitis has rarely been studied. The aim of this study was to investigate the effect of different types of alcoholic beverage in causing acute pancreatitis.

Methods

A follow-up study was conducted, using the Swedish Mammography Cohort and Cohort of Swedish Men, to study the association between consumption of spirits, wine and beer and the risk of acute pancreatitis. No patient with a history of chronic pancreatitis was included and those who developed pancreatic cancer during follow-up were excluded. Multivariable Cox proportional hazards models were used to estimate rate ratios.

Results

In total, 84 601 individuals, aged 46-84 years, were followed for a median of 10 years, of whom 513 developed acute pancreatitis. There was a dose–response association between the amount of spirits consumed on a single occasion and the risk of acute pancreatitis. After multivariable adjustments, there was a 52 per cent (risk ratio 1·52, 95 per cent confidence interval 1·12 to 2·06) increased risk of acute pancreatitis for every increment of five standard drinks of spirits consumed on a single occasion. The association weakened slightly when those with gallstone-related pancreatitis were excluded. There was no association between consumption of wine or beer, frequency of alcoholic beverage consumption including spirits, or average total monthly consumption of alcohol (ethanol) and the risk of acute pancreatitis.

Conclusion

The risk of acute pancreatitis was associated with the amount of spirits consumed on a single occasion but not with wine or beer consumption.

Phenotypic changes in mouse pancreatic stellate cell Ca2+ signaling events following activation in culture and in a disease model of pancreatitis

The specific characteristics of intracellular Ca 2+ signaling and the downstream consequences of these events were investigated in mouse pancreatic stellate cells (PSC) in culture and in situ using multiphoton microscopy in pancreatic lobules. PSC undergo a phenotypic transformation from a quiescent state to a myofibroblast-like phenotype in culture. This is believed to parallel the induction of an activated state observed in pancreatic disease such as chronic pancreatitis and pancreatic cancer. By day 7 in culture, the complement of cell surface receptors coupled to intracellular Ca 2+ signaling was shown to be markedly altered. Specifically, protease-activated receptors (PAR) 1 and 2, responsive to thrombin and trypsin, respectively, and platelet-derived growth factor (PDGF) receptors were expressed only in activated PSC (aPSC). PAR-1, ATP, and PDGF receptor activation resulted in prominent nuclear Ca 2+ signals. Nuclear Ca 2+ signals and aPSC proliferation were abolished by expression of parvalbumin targeted to the nucleus. In pancreatic lobules, PSC responded to agonists consistent with the presence of only quiescent PSC. aPSC were observed following induction of experimental pancreatitis. In contrast, in a mouse model of pancreatic disease harboring elevated K-Ras activity in acinar cells, aPSC were present under control conditions and their number greatly increased following induction of pancreatitis. These data are consistent with nuclear Ca 2+ signaling generated by agents such as trypsin and thrombin, likely present in the pancreas in disease states, resulting in proliferation of "primed" aPSC to contribute to the severity of pancreatic disease.

New prognostic markers for outcome of acute pancreatitis: overview of reporting in 184 studies

OBJECTIVES

The objective of this study was to assess the reporting of studies on new prognostic markers of outcome in acute pancreatitis.

METHODS

We used MEDLINE searches complemented with perusal of review articles' references to identify eligible English-language studies. We included studies evaluating nonroutine markers for acute pancreatitis. Eligible outcomes included Atlanta criteria, Japanese criteria for severity, multiple/single organ failure, complications, interventional treatment, hospitalization length, and death. We generated a 47-item checklist on Acute Pancreatitis Prognosis by adapting a previously constructed reporting guidance instrument for prognostic tumor markers (REMARK [Reporting Recommendations for Tumor Marker Prognostic Studies]). The checklist addresses the reporting of essential information in prognostic studies.

RESULTS

The 184 identified eligible studies reported on 196 different prognostic markers. One hundred forty-four studies (78.3%) found at least 1 prognostic marker to be nominally statistically significant. Significant improvements over time were seen in the reporting for 17 items, but major deficiencies were noted even in 2004-2009 studies. Particularly, 12 items were reported in less than 10% of studies overall and even within the most recent studies.

CONCLUSIONS

Despite some improvements over time, the reporting of important aspects of prognostic studies in acute pancreatitis remains suboptimal. The proposed REMARK-based checklist may help improve the quality and reporting of research in this field.

Genetic basis of chronic pancreatitis in Asia Pacific region

Chronic pancreatitis (CP) is a disease characterized by irreversible destruction and fibrosis of the parenchyma, leading to pancreatic exocrine insufficiency. In developed countries, the etiology for 60% to 70% of CP amongst male patients is alcohol and 25% are classified as idiopathic chronic pancreatitis (ICP). The genetic predisposition to CP could be an inappropriate activation of trypsinogen in the pancreas. Two common haplotypes, c.101A>G (p.N34S) and c.-215G>A, and four intronic alterations of the serine protease inhibitor Kazal type 1 (SPINK1) gene have been found to increase the risk for CP in the Asia Pacific region. Hence, SPINK1 is thought to be a candidate gene for pancreatitis. A loss-of-function alteration in chymotrypsinogen C (CTRC) gene has been shown to be associated with tropical calcific pancreatitis (TCP). Cathepsin B (CTSB) is also found to be associated with TCP. However mutations in cationic and anionic trypsinogen gene do not play an important role in causing CP in Asia Pacific region.

Combined bicarbonate conductance-impairing variants in CFTR and SPINK1 variants are associated with chronic pancreatitis in patients without cystic fibrosis

BACKGROUND & AIMS

Idiopathic chronic pancreatitis (ICP) is a complex inflammatory disorder associated with multiple genetic and environmental factors. In individuals without cystic fibrosis (CF), variants of CFTR that inhibit bicarbonate conductance but maintain chloride conductance might selectively impair secretion of pancreatic juice, leading to trypsin activation and pancreatitis. We investigated whether sequence variants in the gene encoding the pancreatic secretory trypsin inhibitor SPINK1 further increase the risk of pancreatitis in these patients.

METHODS

We screened patients and controls for variants in SPINK1 associated with risk of chronic pancreatitis and in all 27 exons of CFTR. The final study group included 53 patients with sporadic ICP, 27 probands with familial ICP, 150 unrelated controls, 375 additional controls for limited genotyping. CFTR wild-type and p.R75Q were cloned and expressed in HEK293 cells, and relative conductances of HCO(3)(-) and Cl(-) were measured.

RESULTS

SPINK1 variants were identified in 36% of subjects and 3% of controls (odds ratio [OR], 18.1). One variant of CFTR not associated with CF, p.R75Q, was found in 16% of subjects and 5.3% of controls (OR, 3.4). Coinheritance of CFTR p.R75Q and SPINK1 variants occurred in 8.75% of patients and 0.38% of controls (OR, 25.1). Patch-clamp recordings of cells that expressed CFTR p.R75Q showed normal chloride currents but significantly reduced bicarbonate currents (P = .0001).

CONCLUSIONS

The CFTR variant p.R75Q causes a selective defect in bicarbonate conductance and increases risk of pancreatitis. Coinheritance of p.R75Q or CF causing CFTR variants with SPINK1 variants significantly increases the risk of ICP.

Complexin 2 modulates vesicle-associated membrane protein (VAMP) 2-regulated zymogen granule exocytosis in pancreatic acini

Complexins are soluble proteins that regulate the activity of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes necessary for vesicle fusion. Neuronal specific complexin 1 has inhibitory and stimulatory effects on exocytosis by clamping trans-SNARE complexes in a prefusion state and promoting conformational changes to facilitate membrane fusion following cell stimulation. Complexins are unable to bind to monomeric SNARE proteins but bind with high affinity to ternary SNARE complexes and with lower affinity to target SNARE complexes. Far less is understood about complexin function outside the nervous system. Pancreatic acini express the complexin 2 isoform by RT-PCR and immunoblotting. Immunofluorescence microscopy revealed complexin 2 localized along the apical plasma membrane consistent with a role in secretion. Accordingly, complexin 2 was found to interact with vesicle-associated membrane protein (VAMP) 2, syntaxins 3 and 4, but not with VAMP 8 or syntaxin 2. Introduction of recombinant complexin 2 into permeabilized acini inhibited Ca(2+)-stimulated secretion in a concentration-dependent manner with a maximal inhibition of nearly 50%. Mutations of the central α-helical domain reduced complexin 2 SNARE binding and concurrently abolished its inhibitory activity. Surprisingly, mutation of arginine 59 to histidine within the central α-helical domain did not alter SNARE binding and moreover, augmented Ca(2+)-stimulated secretion by 130% of control. Consistent with biochemical studies, complexin 2 colocalized with VAMP 2 along the apical plasma membrane following cholecystokinin-8 stimulation. These data demonstrate a functional role for complexin 2 outside the nervous system and indicate that it participates in the Ca(2+)-sensitive regulatory pathway for zymogen granule exocytosis.

The role of alcohol and smoking in pancreatitis

Chronic alcohol use has been linked to chronic pancreatitis for over a century, but it has not been until the last decade that the role of alcohol in chronic pancreatitis has been elucidated in animals and, only in recent years, in human populations. Although a dose-dependent association between alcohol consumption and chronic pancreatitis may exist, a staistical association has been shown only with the consumption of >or=5 alcoholic drinks per day. Smoking also confers a strong, independent and dose-dependent risk of pancreatitis that may be additive or multiplicative when combined with alcohol. Alcohol increases the risk of acute pancreatitis in several ways and, most importantly, changes the immune response to injury. Genetic factors are also important and further studies are needed to clarify the role of gene-environment interactions in pancreatitis. In humans, aggressive interventional counseling against alcohol use may reduce the frequency of recurrent attacks of disease and smoking cessation may help to slow the progression of acute to chronic pancreatitis.

Cardiocirculatory pathophysiological mechanisms in severe acute pancreatitis

Acute pancreatitis (AP) is a common and potentially lethal acute inflammatory process. Although the majority of patients have a mild episode of AP, 10%-20% develop a severe acute pancreatitis (SAP) and suffer systemic inflammatory response syndrome (SIRS) and/or pancreatic necrosis. The main aim of this article is to review the set of events, first localized in the pancreas, that lead to pancreatic inflammation and to the spread to other organs contributing to multiorganic shock. The early pathogenic mechanisms in SAP are not completely understood but both premature activation of enzymes inside the pancreas, related to an impaired cytosolic Ca²⁺ homeostasis, as well as release of pancreatic enzymes into the bloodstream are considered important events in the onset of pancreatitis disease. Moreover, afferent fibers within the pancreas release neurotransmitters in response to tissue damage. The vasodilator effects of these neurotransmitters and the activation of pro-inflammatory substances play a crucial role in amplifying the inflammatory response, which leads to systemic manifestation of AP. Damage extension to other organs leads to SIRS, which is usually associated with cardiocirculatory physiology impairment and a hypotensive state. Hypotension is a risk factor for death and is associated with a significant hyporesponsiveness to vasoconstrictors. This indicates that stabilization of the patient, once this pathological situation has been established, would be a very difficult task. Therefore, it seems particularly necessary to understand the pathological mechanisms involved in the first phases of AP to avoid damage beyond the pancreas. Moreover, efforts must also be directed to identify those patients who are at risk of developing SAP.

Saline infusion through the pancreatic duct leads to changes in calcium homeostasis similar to those observed in acute pancreatitis

This work focuses on studying the early events associated with pancreatic damage after retrograde infusion through the pancreatic duct in rats. We have analyzed changes in calcium homeostasis and secretory response in pancreatic acini from rats with taurocholate-induced acute pancreatitis. Moreover, in order to test whether pancreatic duct manipulation can trigger damage inside pancreatic acinar cells, we have studied both parameters in acini from animals infused with saline. Our study demonstrates that taurocholate causes evident damage to acinar cells, impairing both calcium homeostasis and secretory response to CCK. In saline, a significant decrease in calcium cytosolic response to CCK was observed. Calcium disturbances similar to those observed in acute pancreatitis appear before secretion blockade and inflammation processes in saline treated rats. These results could be interesting since pancreatitis is associated to clinical procedures that require duct manipulation such as endoscopic retrograde cholangiopancreatography.

Prosurvival Bcl-2 proteins stabilize pancreatic mitochondria and protect against necrosis in experimental pancreatitis

Acinar cells in pancreatitis die through apoptosis and necrosis, the roles of which are different. The severity of experimental pancreatitis correlates directly with the extent of necrosis and inversely, with apoptosis. Apoptosis is mediated by the release of cytochrome c into the cytosol followed by caspase activation, whereas necrosis is associated with the mitochondrial membrane potential (DeltaPsim) loss leading to ATP depletion. Here, we investigate the role of Bcl-2 proteins in apoptosis and necrosis in pancreatitis. We found up-regulation of prosurvival Bcl-2 proteins in pancreas in various experimental models of acute pancreatitis, most pronounced for Bcl-xL. This up-regulation translated into increased levels of Bcl-xL and Bcl-2 in pancreatic mitochondria. Bcl-xL/Bcl-2 inhibitors induced DeltaPsim loss and cytochrome c release in isolated mitochondria. Corroborating the results on mitochondria, Bcl-xL/Bcl-2 inhibitors induced DeltaPsim loss, ATP depletion and necrosis in pancreatic acinar cells, both untreated and hyperstimulated with CCK-8 (in vitro pancreatitis model). Together Bcl-xL/Bcl-2 inhibitors and CCK induced more necrosis than either treatment alone. Bcl-xL/Bcl-2 inhibitors also stimulated cytochrome c release in acinar cells leading to caspase-3 activation and apoptosis. However, different from their effect on pronecrotic signals, the stimulation by Bcl-xL/Bcl-2 inhibitors of apoptotic responses was less in CCK-treated than control cells. Therefore, Bcl-xL/Bcl-2 inhibitors potentiated CCK-induced necrosis but not apoptosis. Correspondingly, transfection with Bcl-xL siRNA stimulated necrosis but not apoptosis in the in vitro pancreatitis model. Further, in animal models of pancreatitis Bcl-xL up-regulation inversely correlated with necrosis, but not apoptosis. Results indicate that Bcl-xL and Bcl-2 protect acinar cells from necrosis in pancreatitis by stabilizing mitochondria against death signals. We conclude that Bcl-xL/Bcl-2 inhibition would aggravate acute pancreatitis, whereas Bcl-xL/Bcl-2 up-regulation presents a strategy to prevent or attenuate necrosis in pancreatitis.

Genetic mechanisms underlying the pathogenesis of tropical calcific pancreatitis

Chronic pancreatitis is known to be a heterogeneous disease with varied etiologies. Tropical calcific pancreatitis (TCP) is a severe form of chronic pancreatitis unique to developing countries. With growing evidence of genetic factors contributing to the pathogenesis of TCP, this review is aimed at compiling the available information in this field. We also propose a two hit model to explain the sequence of events in the pathogenesis of TCP.

The role of free fatty acids, pancreatic lipase and Ca+ signalling in injury of isolated acinar cells and pancreatitis model in lipoprotein lipase-deficient mice

AIM AND METHODS

Recurrent pancreatitis is a common complication of severe hypertriglyceridaemia (HTG) often seen in patients carrying various gene mutations in lipoprotein lipase (LPL). This study investigates a possible pathogenic mechanism of cell damage in isolated mouse pancreatic acinar cells and of pancreatitis in LPL-deficient and in wild type mice.

RESULTS

Addition of free fatty acids (FFA) or of chylomicrons to isolated pancreatic acinar cells caused stimulation of amylase release, and at higher concentrations it also caused cell damage. This effect was decreased in the presence of the lipase inhibitor orlistat. Surprisingly, pancreatic lipase whether in its active or inactive state could act like an agonist by inducing amylase secretion, increasing cellular cGMP levels and converting cell damaging sustained elevations of [Ca(2+)](cyt) to normal Ca(2+) oscillations. Caerulein increases the levels of serum amylase and caused more severe inflammation in the pancreas of LPL-deficient mice than in wild type mice.

CONCLUSION

We conclude that high concentrations of FFA as present in the plasma of LPL-deficient mice and in patients with HTG lead to pancreatic cell damage and are high risk factors for the development of acute pancreatitis. In addition to its enzymatic effect which leads to the generation of cell-damaging FFA from triglycerides, pancreatic lipase also prevents Ca(2+) overload in pancreatic acinar cells and, therefore, counteracts cell injury.

International registries of families at high risk of pancreatic cancer

PURPOSE

To describe the need for multinational registries of families at high risk of pancreatic cancer and the issues surrounding identification of such families.

RESULTS

A consensus position was published describing surveillance of individuals at high risk of pancreatic cancer. Hereditary pancreatitis patients, people with Peutz-Jeghers syndrome, individuals with CDKN2A or BRCA1/2 mutations with a family history of pancreatic cancer and kindred with multiple pancreatic cancers were considered suitable for research-based screening. Mutations responsible for familial predisposition are mostly unknown, although BRCA2 mutations have been identified in some families and a mutation in the palladin gene has been shown to segregate with pancreatic cancer in one kindred. Specific autosomal dominant inheritance of pancreatic cancer risk seems to involve anticipation; this finding aids identification of families and determination of individual risk. Diabetes mellitus is an early symptom of pancreatic cancer, but recent publications suggest that it may not be a significant predisposing factor; this remains controversial. However, in the context of hereditary pancreatitis, diabetes probably does predispose to pancreatic cancer as shown in a recent description of French families.

CONCLUSION

Appropriate inclusion of patients within registries of high-risk families provides a framework for secondary screening and research on risk stratification and early tumorigenesis. and IAP.

VAMP8 is the v-SNARE that mediates basolateral exocytosis in a mouse model of alcoholic pancreatitis

In rodents and humans, alcohol exposure has been shown to predispose the pancreas to cholinergic or viral induction of pancreatitis. We previously developed a rodent model in which exposure to an ethanol (EtOH) diet, followed by carbachol (Cch) stimulation, redirects exocytosis from the apical to the basolateral plasma membrane of acinar cells, resulting in ectopic zymogen enzyme activation and pancreatitis. This redirection of exocytosis involves a soluble NSF attachment receptor (SNARE) complex consisting of syntaxin-4 and synapse-associated protein of 23 kDa (SNAP-23). Here, we investigated the role of the zymogen granule (ZG) SNARE vesicle-associated membrane protein 8 (VAMP8) in mediating basolateral exocytosis. In WT mice, in vitro EtOH exposure or EtOH diet reduced Cch-stimulated amylase release by redirecting apical exocytosis to the basolateral membrane, leading to alcoholic pancreatitis. Further reduction of zymogen secretion, caused by blockade of both apical and basolateral exocytosis and resulting in a more mild induction of alcoholic pancreatitis, was observed in Vamp8(-/-) mice in response to these treatments. In addition, although ZGs accumulated in Vamp8(-/-) acinar cells, ZG-ZG fusions were reduced compared with those in WT acinar cells, as visualized by electron microscopy. This reduction in ZG fusion may account for reduced efficiency of apical exocytosis in Vamp8(-/-) acini. These findings indicate that VAMP8 is the ZG-SNARE that mediates basolateral exocytosis in alcoholic pancreatitis and that VAMP8 is critical for ZG-ZG homotypic fusion.

Association between calcium sensing receptor gene polymorphisms and chronic pancreatitis in a US population: Role of serine protease inhibitor Kazal 1type and alcohol

AIM: To test the hypothesis that calcium sensing receptor (CASR) polymorphisms are associated with chronic pancreatitis (CP), and to determine whether serine protease inhibitor Kazal 1type (SPINK1) N34S or alcohol are necessary co-factors in its etiology.

METHODS: Initially, 115 subjects with pancreatitis and 66 controls were evaluated, of whom 57 patients and 21 controls were predetermined to carry the high-risk SPINK1 N34S polymorphism. We sequenced CASR gene exons 2, 3, 4, 5 and 7, areas containing the majority of reported polymorphisms and novel mutations. Based on the initial results, we added 223 patients and 239 controls to analyze three common nonsynonymous single nucleotide polymorphisms (SNPs) in exon 7 (A986S, R990G, and Q1011E).

RESULTS: The CASR exon 7 R990G polymorphism was significantly associated with CP (OR, 2.01; 95% CI, 1.12-3.59; P = 0.015). The association between CASR R990G and CP was stronger in subjects who reported moderate or heavy alcohol consumption (OR, 3.12; 95% CI, 1.14-9.13; P = 0.018). There was no association between the various CASR genotypes and SPINK1 N34S in pancreatitis. None of the novel CASR polymorphisms reported from Germany and India was detected.

CONCLUSION: Our United States-based study confirmed an association of CASR and CP and for the first time demonstrated that CASR R990G is a significant risk factor for CP. We also conclude that the risk of CP with CASR R990G is increased in subjects with moderate to heavy alcohol consumption.

Mitochondrial mechanisms of death responses in pancreatitis

Pancreatitis is a severe and frequently lethal disorder, a major cause of which is alcohol abuse. Parenchymal cell death is a major complication of pancreatitis. In experimental models of acute pancreatitis, acinar cells have been shown to die through both necrosis and apoptosis, the two principal pathways of cell death. The severity of experimental acute pancreatitis correlates directly with the extent of necrosis and inversely with apoptosis. Thus, understanding the regulation of apoptosis and necrosis is becoming exceedingly important in investigations of the pathogenesis and treatment of pancreatitis. Over the past decade, the mitochondria have emerged as a master regulator of cell death in various physiological and pathological processes. Release of mitochondrial cytochrome c into the cytosol is a central event in apoptosis, whereas mitochondrial depolarization resulting in ATP depletion leads to necrosis. The present review focuses on the mitochondrial mechanisms of death responses in pancreatitis, with emphasis on mitochondrial membrane permeabilization and its role in the balance between apoptosis and necrosis in acute pancreatitis, and alcohol's effects on death responses of pancreatitis.

Pancreatitis risk in primary hyperparathyroidism: relation to mutations in the SPINK1 trypsin inhibitor (N34S) and the cystic fibrosis gene

OBJECTIVE

Primary hyperparathyroidism (pHPT)-related hypercalcemia is considered to represent a risk factor for the development of pancreatitis. We therefore explored whether mutations in genes that were previously identified to increase the risk for pancreatitis coexist in a cohort of 826 patients with pHPT prospectively studied between 1987 and 2002.

METHODS

Among 826 patients with pHPT, 38 patients were identified with pancreatitis (4.6%). DNA was available from 25 patients (13 women/12 men, 16 acute pancreatitis/9 chronic pancreatitis). These individuals and 50 patients with pHPT without pancreatitis were analyzed for mutations in the serine protease inhibitor Kazal type I (SPINK1) gene (N34S) and the cationic trypsinogen gene (PRSS1) (N29I, R122H) by melting curve analysis and DNA sequencing. Sequence analysis of the cystic fibrosis transmembrane conductance regulator (CFTR) gene was carried out for the detection of 36 mutations and the Tn polymorphism.

RESULTS

Four of 25 patients with pHPT and pancreatitis carried the N34S missense mutation in the SPINK1 gene (16%), while all 50 controls (pHPT without pancreatitis) showed no mutation in SPINK1 or PRSS1 genes (P < 0.05 vs controls, P < 0.001 vs general population). CF-causing CFTR mutations were present in four patients (P < 0.05 vs general population), while one patient carried a 5T allele. One patient was transheterozygous (SPINK1: N34S/CFTR: R553X). Mean serum calcium levels in pancreatitis patients (3.1 mmol/L) did not differ significantly from the mean of the entire cohort (3.0 mmol/L) or pHPT patients without pancreatitis (3.1 mmol/L).

CONCLUSION

Pancreatitis risk is approximately 10-fold elevated in pHPT, but pancreatitis occurs infrequently. This indicates an existing but minor impact of pHPT-related hypercalcemia. If pancreatitis occurs, it seems associated with genetic risk factors such as mutations in the SPINK1 and CFTR genes. In contrast, a combination of both hypercalcemia and genetic variants in SPINK1 or CFTR increases the risk to develop pancreatitis in patients with pHPT.

Hereditary pancreatitis amlodipine trial: a pilot study of a calcium-channel blocker in hereditary pancreatitis

OBJECTIVES

Hereditary pancreatitis (HP) is a form of recurrent acute pancreatitis (AP) mediated by mutations in cationic trypsinogen (PRSS1). Mutations cluster in the calcium-associated regulator regions of PRSS1. In rats, calcium-channel blockers (CCB) prevent hyperstimulation-associated AP. Because of the potential importance of hyperstimulation in triggering episodes of AP in HP, we designed a pilot study to evaluate the safety and potential benefit of CCB use in HP.

METHODS

Subjects 6 years or older had a PRSS1 mutation, recurrent AP, and pain. Total study duration was 16 weeks. Amlodipine was given during weeks 0 to 11. Dose (2.5, 5, or 10 mg) was based on weight (range, 0.08-0.17 mg x kg(-1) x d(-1)). Subjects filled a daily diary including pain (0-10 scale) and blood pressure reading. Clinical assessments occurred at weeks -4, 0, 1, 2, 6, 10, 11, and 12. Subjects filled a Medical Outcomes Study Short-Form Survey version 2 (SF-10 for children <14 years old) at weeks -4, 0, 6, and 10. Data were compared for weeks -4 to 0 and 6 to 10.

RESULTS

Nine subjects signed informed consent (4 males; 12-52 years old). Four were excluded during the screening phase. Drug was discontinued in one due to development of unilateral lower-extremity numbness. Four subjects (12-31 years old) completed the study. Mean blood pressure, laboratory tests, physical findings, and daily pain scores did not clinically significantly differ before and during drug therapy, but all reported reduced symptoms. Three reduced analgesic use. Three had improved scores on the Medical Outcomes Study Short-Form Survey version 2.

CONCLUSIONS

Amlodipine is generally safe in subjects with HP and does not increase pain or episodes of AP. Further research into the mechanism of CCB on pancreatitis would be important to provide a pathophysiologic basis to support further trials in HP.

Recent insights into the cellular mechanisms of acute pancreatitis

In acute pancreatitis, initiating cellular events causing acinar cell injury includes co-localization of zymogens with lysosomal hydrolases, leading to premature enzyme activation and pathological exocytosis of zymogens into the interstitial space. This is followed by processes that accentuate cell injury; triggering acute inflammatory mediators, intensifying oxidative stress, compromising the microcirculation and activating a neurogenic feedback. Such localized events then progress to a systemic inflammatory response leading to multiorgan dysfunction syndrome with resulting high morbidity and mortality. The present review discusses some of the most recent insights into each of these cellular processes postulated to cause or propagate the process of acute pancreatitis, and also the role of alcohol and genetics.

Calcium signalling and pancreatic cell death: apoptosis or necrosis?

Secretagogues, such as cholecystokinin and acetylcholine, utilise a variety of second messengers (inositol trisphosphate, cADPR and nicotinic acid adenine dinucleotide phosphate) to induce specific oscillatory patterns of calcium (Ca(2+)) signals in pancreatic acinar cells. These are tightly controlled in a spatiotemporal manner, and are coupled to mitochondrial metabolism necessary to fuel secretion. When Ca(2+) homeostasis is disrupted by known precipitants of acute pancreatitis, for example, hyperstimulation or non-oxidative ethanol metabolites, Ca(2+) stores (endoplasmic reticulum and acidic pool) become depleted and sustained cytosolic [Ca(2+)] elevations replace transient signals, leading to severe consequences. Sustained mitochondrial depolarisation, possibly via opening of the mitochondrial permeability transition pore (MPTP), elicits cellular ATP depletion that paralyses energy-dependent Ca(2+) pumps causing cytosolic Ca(2+) overload, while digestive enzymes are activated prematurely within the cell; Ca(2+)-dependent cellular necrosis ensues. However, when stress to the acinar cell is milder, for example, by application of the oxidant menadione, release of Ca(2+) from stores leads to oscillatory global waves, associated with partial mitochondrial depolarisation and transient MPTP opening; apoptotic cell death is promoted via the intrinsic pathway, when associated with generation of reactive oxygen species. Apoptosis, induced by menadione or bile acids, is potentiated by inhibition of an endogenous detoxifying enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1), suggesting its importance as a defence mechanism that may influence cell fate.

Pancreatic acinar cells express vesicle-associated membrane protein 2- and 8-specific populations of zymogen granules with distinct and overlapping roles in secretion

Previous studies have demonstrated roles for vesicle-associated membrane protein 2 (VAMP 2) and VAMP 8 in Ca(2+)-regulated pancreatic acinar cell secretion, however, their coordinated function in the secretory pathway has not been addressed. Here we provide evidence using immunofluorescence microscopy, cell fractionation, and SNARE protein interaction studies that acinar cells contain two distinct populations of zymogen granules (ZGs) expressing either VAMP 2 or VAMP 8. Further, VAMP 8-positive granules also contain the synaptosome-associated protein 29, whereas VAMP 2-expressing granules do not. Analysis of acinar secretion by Texas red-dextran labeling indicated that VAMP 2-positive ZGs mediate the majority of exocytotic events during constitutive secretion and also participate in Ca(2+)-regulated exocytosis, whereas VAMP 8-positive ZGs are more largely involved in Ca(2+)-stimulated secretion. Previously undefined functional roles for VAMP and syntaxin isoforms in acinar secretion were established by introducing truncated constructs of these proteins into permeabilized acini. VAMP 2 and VAMP 8 constructs each attenuated Ca(2+)-stimulated exocytosis by 50%, whereas the neuronal VAMP 1 had no effects. In comparison, the plasma membrane SNAREs syntaxin 2 and syntaxin 4 each inhibited basal exocytosis, but only syntaxin 4 significantly inhibited Ca(2+)-stimulated secretion. Syntaxin 3, which is expressed on ZGs, had no effects. Collectively, these data demonstrate that individual acinar cells express VAMP 2- and VAMP 8-specific populations of ZGs that orchestrate the constitutive and Ca(2+)-regulated secretory pathways.