Stimulation of stellate cells by injured acinar cells: a model of acute pancreatitis induced by alcohol and fat (VLDL)

Molecular mechanisms of pancreatic myofibroblast activation in chronic pancreatitis and pancreatic ductal adenocarcinoma

Pancreatic fibrosis (PF) is an essential component of the pathobiology of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Activated pancreatic myofibroblasts (PMFs) are crucial for the deposition of the extracellular matrix, and fibrotic reaction in response to sustained signaling. Consequently, understanding of the molecular mechanisms of PMF activation is not only critical for understanding CP and PDAC biology but is also a fertile area of research for the development of novel therapeutic strategies for pancreatic pathologies. This review analyzes the key signaling events that drive PMF activation including, initiating signals from transforming growth factor-β1, platelet derived growth factor, as well as other microenvironmental cues, like hypoxia and extracellular matrix rigidity. Further, we discussed the intracellular signal events contributing to PMF activation, and crosstalk with different components of tumor microenvironment. Additionally, association of epidemiologically established risk factors for CP and PDAC, like alcohol intake, tobacco exposure, and metabolic factors with PMF activation, is discussed to comprehend the role of lifestyle factors on pancreatic pathologies. Overall, this analysis provides insight into the biology of PMF activation and highlights salient features of this process, which offer promising therapeutic targets.

Regulation of Pancreatic Fibrosis by Acinar Cell-Derived Exosomal miR-130a-3p via Targeting of Stellate Cell PPAR-γ

Introduction

As endogenous miRNA carriers, exosomes play a role in the pathophysiological processes of various diseases. However, their functions and regulation mechanisms in pancreatic fibrosis remain unclear.

Methods

In this study, an RNA microarray was used to detect differentially expressed exosomal miR-130a-3p in AR42J cells before and after taurolithocholate (TLC) treatment. mRNA-seq was used to screen differentially expressed genes before and after pancreatic stellate cell (PSC) activation. We used the STRING database to construct a protein-protein interaction (PPI) network for differentially expressed genes, used CytoNCA to analyze the centrality of the PPI network, and identified 10 essential proteins in the biological network. Then, the TargetScan and miRanda databases were used to predict the target genes of miR-130a-3p. The intersections of the target genes and the mRNAs encoding the 10 essential proteins were identified to construct miR-130a-3p/peroxisome proliferator-activated receptor gamma (PPAR-γ) pairs. Fluorescence labeling of exosomes and dynamic tracing showed that exosomes can fuse with the cell membranes of PSCs and transport miR-130a-3p into PSCs. A luciferase reporter gene assay was used to confirm that miR-130a-3p can bind to PPAR-γ to inhibit PPAR-γ expression. In vitro and in vivo functional experiments were performed for gain-of-function studies and loss-of-function studies, respectively.

Results

The studies showed that acinar cell-derived exosomal miR-130a-3p promotes PSC activation and collagen formation through targeting of stellate cellular PPAR-γ. Knockdown of miR-130a-3p significantly improved pancreatic fibrosis. Notably, miR-130a-3p knockdown reduced serum levels of hyaluronic acid (HA) and β-amylase and increased the C-peptide level to protect endocrine and exocrine pancreatic functions and the function of endothelial cells.

Conclusion

This study revealed that the exosomal miR-130a-3p/PPAR-γ axis participates in PSC activation and the mechanism of chronic pancreatitis (CP) with fibrosis, thus providing a potential new target for the treatment of chronic pancreatic fibrosis.

Sheng-jiang powder ameliorates obesity-induced pancreatic inflammatory injury via stimulating activation of the AMPK signalling pathway in rats

AIM

To investigate the mechanisms by which Sheng-jiang powder (SJP) ameliorates obesity-induced pancreatic inflammatory injury.

METHODS

Sprague-Dawley rats were randomized into three groups: normal group (NG), obese group (HLG), or SJP treatment group (HSG). Obesity was induced by feeding a high-fat diet in the HLG and HSG, while the NG received standard chow. Rats were euthanized after 12 wk, and blood and pancreatic tissues were collected for histopathological analyses. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor beta (TGF-β) expression, serum triglyceride and adiponectin levels, and apoptosis in pancreatic acinar cells were assessed. A high-fat AR42J acinar cell injury model was established using very low-density lipoprotein (VLDL). AR42J acinar cell culture supernatant, treated with different interventions, was applied to seven groups of pancreatic stellate cells (PSCs). The proliferation of PSCs and the expression of fibronectin and type I collagenase were assessed.

RESULTS

Compared with the NG, we found higher pathological scores for pancreatic tissues, lower serum adiponectin levels, higher expression levels of NF-κB in pancreatic tissues and TGF-β in pancreatic inflammatory cells, and increased apoptosis among pancreatic acinar cells for the HLG (P < 0.05). Compared with the HLG, we found reduced body weight, Lee’s index scores, serum triglyceride levels, and pathological scores for pancreatic tissues; higher serum adiponectin levels; and lower expression levels of NF-κB, in pancreatic tissue and TGF-β in pancreatic inflammatory cells for the HSG (P < 0.05). The in vitro studies showed enhanced PSC activation and increased expression levels of fibronectin and type I collagenase after SJP treatment. An adenosine 5‘-monophosphate-activated protein kinase (AMPK) inhibitor inhibited PSC activation.

CONCLUSION

SJP may ameliorate obesity-induced pancreatic inflammatory injury in rats by regulating key molecules of the adiponectin-AMPK signalling pathway.

Effect of intrapancreatic fat on diabetes outcomes after total pancreatectomy with islet autotransplantation

BACKGROUND

Pancreatic fat may adversely affect β-cell mass and function, possibly via local release of non-esterified fatty acids, and proinflammatory and vasoactive factors released by adipose tissue. However, the effects of intrapancreatic fat in patients with chronic pancreatitis undergoing total pancreatectomy with islet autotransplantation (TPIAT) have not been studied. This study investigated whether pancreatic fatty infiltration has a negative effect on metabolic outcomes following TPIAT.

METHODS

The association between pancreatic fatty infiltration and diabetes outcomes was studied in 79 patients with low or high pancreatic fat content (LPF [n = 53] and HPF [n = 26], respectively) undergoing TPIAT. Pancreatic fatty infiltration was stratified using gross examinations during isolation and validated with histomorphometry of archived histology samples.

RESULTS

Fat area percentage in histology samples differed significantly between the LPF and HPF groups (2.1% ± 4.3% vs 10.6% ± 8.9%, respectively; P = 0.0009). Insulin dependence was more common in the HPF group, whereas more patients in the LPF group were insulin independent or on partial insulin supplementation at 1 year (P = 0.022). Furthermore, 1- and 2-h glucose concentrations during mixed-meal tolerance tests were significantly higher in the HPF group (P = 0.032 and 0.027, respectively) and β-scores (a composite measure of islet function and metabolic control) were significantly greater in the LPF than HPF group (6.1 ± 1.7 vs 4.6 ± 2.0; P = 0.034).

CONCLUSIONS

Patients with HPF were more likely to be insulin dependent, with higher postprandial glucose excursion, suggesting that intrapancreatic fat may lead to β-cell dysfunction with detrimental effects on diabetes outcomes after TPIAT.

A Mouse Model of Chronic Pancreatitis Induced by an Alcohol and High Fat Diet

Background/Aims:

Study of acute pancreatitis in chemically-induced rodent models has provided useful data; models of alcoholic chronic pancreatitis have not been available in mice. The aim of the present study was to characterize a mouse model of chronic pancreatitis induced solely with an alcohol and high fat (AHF) diet.

Methods:

Mice were fed a liquid high fat diet containing 6% alcohol as well as a high fat supplement (57% total dietary fat) over a period of five months or as control, normal chow ad libitum. Pain related measures utilized as an index of pain included mechanical sensitivity of the hind paws determined using von Frey filaments and a smooth/rough textured plate. A modified hotplate test contributed information about higher order behavioral responses to visceral hypersensitivity. Mice underwent mechanical and thermal testing both with and without pharmacological treatment with a peripherally restricted μ-opioid receptor agonist, loperamide.

Results:

Mice on the AHF diet exhibited mechanical and heat hypersensitivity as well as fibrotic histology indicative of chronic pancreatitis. Low dose, peripherally restricted opiate loperamide attenuated both mechanical and heat hypersensitivity.

Conclusion:

Mice fed an alcohol and high fat diet develop histology consistent with chronic pancreatitis as well as opioid sensitive mechanical and heat hypersensitivity.

Antifibrotic Effect of Saturated Fatty Acids via Endoplasmic Reticulum Stress Response in Rat Pancreatic Stellate Cells

OBJECTIVES

We investigated the effect of saturated fatty acids on chronic pancreatitis pathogenesis by elucidating the endoplasmic reticulum (ER) stress response in pancreatic stellate cells (PSCs), which are major effector cells in pancreatic fibrosis.

METHODS

Wistar Bonn/Kobori rats were fed either control diet or high-fat diet (HFD) for 4 weeks. Meanwhile, cultured rat PSCs were stimulated with thapsigargin, an ER stress inducer, or palmitic acid (PA). Pancreatic fibrosis, expressions of fibrosis-related and ER stress-related proteins and mRNA, cell viability, and apoptosis were examined.

RESULTS

The HFD reduced fibrosis and α-smooth muscle actin expression (ie, activated PSCs) but upregulated ER stress-related mRNA expression in the pancreas of young HFD-fed Wistar Bonn/Kobori rats. Induction of ER stress response in PSCs with thapsigargin or PA induced apoptosis, activated the protein kinase-like ER kinase (PERK) pathway, inhibited cell viability, and downregulated fibrosis-related protein and mRNA expression. The PERK inhibitor negated PA-induced ER stress response.

CONCLUSIONS

Saturated fatty acids can inhibit but may not promote the fibrogenesis of chronic pancreatitis, at least in the early stage, via an ER stress response (ie, the PERK pathway) in PSCs. Moreover, induction of an apoptotic ER stress response in PSCs might be a novel therapeutic strategy for pancreatic fibrosis.

Reciprocal stimulation of pancreatic acinar and stellate cells in a novel long-term in vitro co-culture model

BACKGROUND/OBJECTIVES

Pancreatic stellate cells (PSCs) are the key fibrogenic cells in the pancreas. Acinar cell injury is known to trigger PSC activation. To facilitate the experimental analysis of the crosstalk between acinar cells and PSCs, an in vitro system for their long-term co-cultivation was developed.

MATERIALS AND METHODS

PSCs and acinar cells capable of retaining their secretory phenotype in long-term in vitro culture were obtained from mouse pancreata. A dual-chamber co-culture model was built in 24-well format with acinar cells seeded in the wells and PSCs in tissue culture inserts. Acinar cell-3T3 fibroblast co-cultures served as controls. After 4-day maintenance, the acinar compartment was analyzed for cell morphology, secretory capability, necrosis (HMGB1), apoptosis (TUNEL) and inflammation (NFκB). PSCs were analyzed for migratory activity and extracellular matrix (ECM) protein expression. The results were compared to parallel monocultures.

RESULTS

Acinar cells in monoculture and in co-culture with fibroblasts exhibited a healthy monolayer arrangement and an ability to respond to 0.1 nM caerulein stimulus by increased amylase release. Co-culture with PSCs caused marked changes in acinar cell morphology and rendered them insensitive to secretagogue stimulus. Activation of NFκB and necrotic changes, but not apoptosis, were identified in co-cultured acinar cells. Co-culture increased the migratory activity and ECM protein expression of PSCs.

CONCLUSIONS

Humoral interactions between acinar and PSCs in co-culture were shown to reciprocally affect their cellular functions. With its two separable cell compartments the co-culture system provides a versatile culture setting that allows independent manipulation and analysis of both cell types.

Isolation and characterization of human islet stellate cells

BACKGROUND AND AIMS

We have previously demonstrated that islet stellate cells (ISCs) exhibiting a similar phenotype to classical pancreatic stellate cells (PSCs) could be isolated from rat islets, where they may contribute to islet fibrosis in type 2 diabetes mellitus (T2DM). This study was designed to determine whether human islets also contain ISC.

MATERIALS AND METHODS

Using standard explants techniques, human ISCs were enriched from freshly isolated human islets. Immunofluorescence visualization of markers for PSCs(α-smooth muscle actin;α-SMA), desmin, vimentin, glial fibrillary acidic protein (GFAP) was used to characterize the human ISC. Cell counting kit-8 (CCK-8) was used to assess the proliferation of ISC. The wound-healing assay and the transwell migration were used to assess the migration capacity of ISC. Immunofluorescence against collagen typesI (col-I), collagen typesIII (col-III) and fibronectin (FN) was performed to identify extracellular matrix (ECM) component synthesized by ISC. Adipogenic and osteogenic differentiation were tried to detected stem cell potential.

RESULTS

In culture, ISC with triangular shape grow out from human islets. The passaged ISC expressed α-SMA, desmin, vimentin, GFAP and was positive for col-I, col-III and FN. The proliferation and migration ability of ISC was significantly slower than those of PSC. And both the human PSC and ISC were able to differentiate in vitro into adipocyte- and osteoblast-like cells.

CONCLUSION

Similar to our previous rat experiment, the current study shows that human islets also contain ISC which is phenotypically similar but not identical to human PSC.

Role of Parathyroid Hormone-Related Protein Signaling in Chronic Pancreatitis

Chronic pancreatitis (CP), a progressive inflammatory disease where acini are destroyed and replaced by fibrous tissue, increases the risk for pancreatic cancer. Risk factors include alcohol, smoking, and obesity. The effects of these risk factors are exacerbated in patients with mutations in genes that predispose to CP. The different environmental and genetic factors produce the same clinical phenotype; once CP develops, disease course is the same regardless of etiology. Critical questions still need to be answered to understand what modifies predisposition to develop CP in persons exposed to risk factors. We postulate that risk factors modulate endogenous pathways, with parathyroid hormone-related protein (PTHrP) signaling being one such pathway. In support, PTHrP levels are elevated in mice treated with alcohol, and in mouse models of cerulein- and pancreatic duct ligation-induced CP. Disrupting the Pthrp gene in acinar cells exerts protective effects (decreased edema, histological damage, amylase and cytokine release, and fibrosis) in these CP models. PTHrP levels are elevated in human CP. Currently, CP care lacks specific pharmacological interventions. Targeting PTHrP signaling may present a novel therapeutic strategy that inhibits pancreatic inflammation and fibrosis, especially since the risk of developing pancreatic cancer is strongly associated with duration of chronic inflammation.

Pharmacological attenuation of chronic alcoholic pancreatitis induced hypersensitivity in rats

AIM

To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices.

METHODS

Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States).

RESULTS

Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher incidence of single and small 2-10 cell insulin-positive cell clusters (P < 0.05). Insulin expressing islet of Langerhans cells appeared hypertrophied while islet number and area measurements were not different from controls. Weekly behavioral tests determined that mechanical and heat sensitivities were significantly increased by 4 wk on AHF diet compared to controls. Hypersensitivity was attenuated with efficacy similar to morphine with single dose treatment of either metabotropic glutamate receptor 2/3 agonist APDC, or nociceptin, the endogenous ligand for opioid-receptor-like 1 receptor.

CONCLUSION

The AHF diet induces a chronic alcoholic pancreatitis in rats with measurable features resembling clinical patients with chronic pancreatitis and type 3c diabetes mellitus.

Extended exenatide administration enhances lipid metabolism and exacerbates pancreatic injury in mice on a high fat, high carbohydrate diet

This study expanded upon a previous study in mice reporting a link between exenatide treatment and exocrine pancreatic injury by demonstrating temporal and dose responses and providing an initial mechanistic hypothesis. The design of the present study included varying lengths of exenatide exposure (3, 6 weeks to 12 weeks) at multiple concentrations (3, 10, or 30 µg/kg) with multiple endpoints (histopathology evaluations, immunoassay for cytokines, immunostaining of the pancreas, serum chemistries and measurement of trypsin, amylase, and, lipase, and gene expression profiles). Time- and dose-dependent exocrine pancreatic injury was observed in mice on a high fat diet treated with exenatide. The morphological changes identified in the pancreas involved acinar cell injury and death (autophagy, apoptosis, necrosis, and atrophy), cell adaptations (hypertrophy and hyperplasia), and cell survival (proliferation/regeneration) accompanied by varying degrees of inflammatory response leading to secondary injury in pancreatic blood vessels, ducts, and adipose tissues. Gene expression profiles indicated increased signaling for cell survival and altered lipid metabolism in exenatide treated mice. Immunohistochemistry supported gene expression findings that exenatide caused and/or exacerbated pancreatic injury in a high fat diet environment potentially by further increasing high fat diet exacerbated lipid metabolism and resulting oxidative stress. Further investigation is required to confirm these findings and determine their relevance to human disease.

Pancreatic fat accumulation, fibrosis, and acinar cell injury in the Zucker diabetic fatty rat fed a chronic high-fat diet

OBJECTIVE

The histological alteration of the exocrine pancreas in obesity has not been clarified. In the present study, we investigated biochemical and histological changes in the exocrine pancreas of obese model rats.

METHODS

Zucker lean rats were fed a standard diet, and Zucker diabetic fatty (ZDF) rats were divided into 2 groups fed a standard diet and a high-fat diet, respectively. These experimental groups were fed each of the diets from 6 weeks until 12, 18, 24 weeks of age. We performed blood biochemical assays and histological analysis of the pancreas.

RESULTS

In the ZDF rats fed a high-fat diet, the ratio of accumulated pancreatic fat area relative to exocrine gland area was increased significantly at 18 weeks of age in comparison with the other 2 groups (P < 0.05), and lipid droplets were observed in acinar cells. Subsequently, at 24 weeks of age in this group, pancreatic fibrosis and the serum exocrine pancreatic enzyme levels were increased significantly relative to the other 2 groups (P < 0.01).

CONCLUSIONS

In ZDF rats fed a chronic high-fat diet, fat accumulates in pancreatic acinar cells, and this fatty change seems to be related to subsequent pancreatic fibrosis and acinar cell injury.

High glucose aggravates the detrimental effects of pancreatic stellate cells on Beta-cell function

Background and Aims. We here assess the effects of PSCs on β-cell function and apoptosis in vivo and in vitro. Materials and Methods. PSCs were transplanted into Wistar and Goto-Kakizaki (GK) rats. Sixteen weeks after transplantation, β-cell function, apoptosis, and islet fibrosis were assessed. In vitro the effects of PSCs conditioned medium (PSCs-CM) and/or high concentration of glucose on INS-1 cell function was assessed by measuring insulin secretion, INS-1 cell survival, apoptosis, and endoplasmic reticulum stress (ER stress) associated CHOP expression. Results. PSCs transplantation exacerbated the impaired β-cell function in GK rats, but had no significant effects in Wistar rats. In vitro, PSCs-CM caused impaired INS-1 cell viability and insulin secretion and increased apoptosis, which were more pronounced in the presence of high glucose. Conclusion. Our study demonstrates that PSCs induce β-cell failure in vitro and in vivo.

Role of pancreatic fat in the outcomes of pancreatitis

The role of obesity in relation to various disease processes is being increasingly studied, with reports over the last several years increasingly mentioning its association with worse outcomes in acute disease. Obesity has also gained recognition as a risk factor for severe acute pancreatitis (SAP).The mortality in SAP may be as high as 30% and is usually attributable to multi system organ failure (MSOF) earlier in the disease, and complications of necrotizing pancreatitis later [9-11]. To date there is no specific treatment for acute pancreatitis (AP) and the management is largely expectant and supportive. Obesity in general has also been associated with poor outcomes in sepsis and other pathological states including trauma and burns. With the role of unsaturated fatty acids (UFA) as propagators in SAP having recently come to light and with the recognition of acute lipotoxicity, there is now an opportunity to explore different strategies to reduce the mortality and morbidity in SAP and potentially other disease states associated with such a pathophysiology. In this review we will discuss the role of fat and implications of the consequent acute lipotoxicity on the outcomes of acute pancreatitis in lean and obese states and during acute on chronic pancreatitis.

Isolation and characterization of islet stellate cells in rat

The central role of PSCs in pancreatic fibrogenesis is well established. However, the mechanism responsible for the islet fibrosis presenting in the late stage of T2DM has not been fully elucidated. This study was designed to determine whether the endocrine pancreatic islets contain cells resembling PSCs. PSCs were isolated from pancreas using standard explants techniques. A similar method was used to acquire ISCs. Adherent ISCs with a stellate, angular morphology migrated from the edge of cultured islets within 48 h of primary culture. ISCs contained fewer lipid droplets than equivalent PSCs, and their rapid disappearance accompanied by the increased expression of α-SMA suggested that ISCs were more rapidly activated than PSCs in vitro. They expressed α-SMA, vimentin, GFAP and were positive for ECM components col-I, col-III and FN, all of which are characteristics of classical PSCs. However, ISCs differed from PSCs by having reduced rates of proliferation and migration in vitro. Our in vitro study shows that isolated islets contain a population of stellate cells which are phenotypically similar but not identical to PSCs. In view of the established role of PSCs in pancreatic fibrosis, we suggest that these may contribute to islet fibrosis in T2DM.

BMP2 inhibits TGF-β-induced pancreatic stellate cell activation and extracellular matrix formation

Activation of pancreatic stellate cells (PSCs) by transforming growth factor (TGF)-β is the key step in the development of pancreatic fibrosis, a common pathological feature of chronic pancreatitis (CP). Bone morphogenetic proteins (BMPs), members of the TGF-β superfamily, have anti-fibrogenic functions, in contrast to TGF-β, in the kidney, lung, and liver. However, it is not known whether BMPs have an anti-fibrogenic role in the pancreas. The current study was designed to investigate the potential anti-fibrogenic role of BMPs in the pancreas using an in vivo CP model and an in vitro PSC model. CP was induced by repetitive intraperitoneal injections of cerulein in adult Swiss Webster mice. The control mice received saline injections. Compared with the control, cerulein injections induced a time-dependent increase in acinar injury and progression of fibrosis and a steady increase in inflammation. Cerulein injections also induced increases of the extracellular matrix (ECM) protein fibronectin and of α-smooth muscle actin (α-SMA)-positive stellate cells (PSCs). The mice receiving cerulein injections showed increased BMP2 protein levels and phosphorylated Smad1 levels up to 4 wk and then declined at 8 wk to similar levels as the control. In vitro, the isolated mouse and human PSCs were cultured and pretreated with BMP2 followed by TGF-β treatment. BMP2 pretreatment inhibited TGF-β-induced α-SMA, fibronectin, and collagen type Ia expression. Knocking down Smad1 with small-interfering RNA reversed the inhibitory effect of BMP2 on TGF-β-induced α-SMA and fibronectin expression. Thus, BMP2 opposes the fibrogenic function of TGF-β in PSCs through the Smad1 signaling pathway.

Alcohol abuse-related severe acute pancreatitis with rhabdomyolysis complications

Non-traumatic rhabdomyolysis is a rare complication of acute pancreatitis. One of the major risk factors of both acute pancreatitis and rhabdomyolysis is alcohol abuse. However, only a few studies have reported the prognosis and association of severe acute pancreatitis (SAP) and rhabdomyolysis in alcohol abuse patients. In the present study, we report two cases presenting with SAP complicated by rhabdomyolysis following high-dose alcohol intake. The disease onset, clinical manifestations, laboratory data, diagnosis and treatment procedure of each patient were recorded, and the association with rhabdomyolysis was analyzed. Alcohol consumption was the most predominant cause of SAP and rhabdomyolysis in these patients. SAP-related rhabdomyolysis was primarily induced by the toxicity associated with pancreatic necrosis. The laboratory tests revealed that the concentration of serum creatine kinase (CK) and myoglobin increased and acute renal failure symptoms were present, which provided an exact diagnosis for SAP-induced rhabdomyolysis. Rhabdomyolysis and subsequent hypermyoglobinuria severely impaired kidney function and aggravated hypocalcemia. The therapy of early stage SAP complicated by rhabdomyolysis involved liquid resuscitation support. When first stage treatment fails, blood purification should be performed immediately. Both patients developed multiple organ failure (MOF) and succumbed to the disease. Considering the two cases presented, we conclude that alcohol-related SAP complicated by rhabdomyolysis may have a poor clinical prognosis.

miR-15b and miR-16 induce the apoptosis of rat activated pancreatic stellate cells by targeting Bcl-2 in vitro

OBJECTIVES

Activated pancreatic stellate cells (PSCs) play a pivotal role in the development of pancreatic diseases, especially chronic pancreatitis and pancreatic cancer. MicroRNAs have become a focal point of interest as post-transcriptional regulators of gene expression via their interaction with the 3' untranslated region of target mRNAs, which results in gene silencing. We examined the relative expression of microRNAs (miR-15b and miR-16) and their target gene, Bcl-2, during activation of rat PSCs, and determined their effects on apoptosis of rat PSCs in vitro.

METHODS

miR-15b and miR-16 expression levels were analyzed in quiescent and activated PSCs by stem-loop RT-PCR. In addition, the effects of miR-15b and miR-16 on apoptosis of activated PSCs were investigated by immunofluorescence microscopy with Hoechst 33342 staining, and flow cytometry with annexin-V/propidium (PI) co-labeling. Bcl-2 and Bcl-xl were also analyzed by real-time RT-PCR and Western blotting.

RESULTS

During activation of PSCs, from the quiescent stage to activated stage, miR-15b and miR_16 were downregulated, while Bcl-2 expression was upregulated. Restoring intracellular miRNA levels by miR-15b and miR-16 administration greatly reduced Bcl-2 protein levels, and significantly induced apoptosis in activated PSCs.

CONCLUSIONS

miR-15b and miR-16 could induce apoptosis of rat PSCs by targeting Bcl-2.

Vasoactive intestinal peptide reduces oxidative stress in pancreatic acinar cells through the inhibition of NADPH oxidase

Vasoactive intestinal peptide (VIP) attenuates experimental acute pancreatitis (AP) by inhibition of cytokine production from inflammatory cells. It has been suggested that reactive oxygen species (ROS) as well as cytokines play pivotal roles in the early pathophysiology of AP. This study aimed to clarify the effect of VIP on the oxidative condition in pancreas, especially pancreatic acinar cells (acini). Hydrogen peroxide (H(2)O(2))-induced intracellular ROS, assessed with CM-H(2)DCFDA, increased time- and dose-dependently in acini isolated from rats. Cell viability due to ROS-induced cellular damage, evaluated by MTS assay, was decreased with ≥100 μmol/L H(2)O(2). VIP significantly inhibited ROS production from acini and increased cell viability in a dose-dependent manner. Expression of antioxidants including catalase, glutathione reductase, superoxide dismutase (SOD) 1 and glutathione peroxidase was not altered by VIP except for SOD2. Furthermore, Nox1 and Nox2, major components of NADPH oxidase, were expressed in pancreatic acini, and significantly increased after H(2)O(2) treatment. Also, NADPH oxidase activity was provoked by H(2)O(2). VIP decreased NADPH oxidase activity, which was abolished by PKA inhibitor H89. These results suggested that VIP affected the mechanism of ROS production including NADPH oxidase through induction of a cAMP/PKA pathway. In conclusion, VIP reduces oxidative stress in acini through the inhibition of NADPH oxidase. These results combined with findings of our previous study suggest that VIP exerts its protective effect in pancreatic damage, not only through an inhibition of cytokine production, but also through a reduction of the injury caused by oxidative stress.

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.

Alcoholic acute pancreatitis: pathogenesis and clinical characteristics

Animal and clinical studies have shown that alcohol and its metabolic products, endotoxin, viral infection, drinking pattern, smoking, obesity, genetic variability, and gene polymorphisms were very important in the pathogenesis of alcoholic acute pancreatitis (AAP). The morbidity of AAP has been increased in the past decade, and male gender is strongly associated with increased risk of AAP. The mortality of AAP is high, while the quality of life of survivors of severe AAP is low. In this paper, we review the pathogenesis and clinical characteristics of AAP.

Acute ethanol exposure disrupts actin cytoskeleton and generates reactive oxygen species in c6 cells

Central nervous system dysfunctions are among the most significant effects of exposure to ethanol and the glial cells that play an important role in maintaining neuronal function, are extremely involved with these effects. The actin cytoskeleton plays a crucial role in a wide variety of cellular functions, especially when there is some injury. Therefore the aim of the present study was to analyze the short-term effects of ethanol (50, 100 and 200 mM) on the cytoskeleton of C6 glioma cells. Here we report that acute ethanol exposure profoundly disrupts the actin cytoskeleton in C6 cells decreasing stress fiber formation and downregulating RhoA and vinculin immunocontent. In contrast, microtubule and GFAP networks were not altered. We further demonstrate that anti-oxidants prevent ethanol-induced actin alterations, suggesting that the actions of ethanol on the actin cytoskeleton are related with generation of reactive oxygen species (ROS) in these cells. Our results show that ethanol at concentrations described to be toxic to the central nervous system was able to target the cytoskeleton of C6 cells and this effect could be related with increased ROS generation. Therefore, we propose that the dynamic restructuring of the cytoskeleton of glial cells might contribute to the response to the injury provoked by binge-like ethanol exposure in brain.

Interaction of stellate cells with pancreatic carcinoma cells

Pancreatic cancer is characterized by its late detection, aggressive growth, intense infiltration into adjacent tissue, early metastasis, resistance to chemo- and radiotherapy and a strong “desmoplastic reaction”. The dense stroma surrounding carcinoma cells is composed of fibroblasts, activated stellate cells (myofibroblast-like cells), various inflammatory cells, proliferating vascular structures, collagens and fibronectin. In particular the cellular components of the stroma produce the tumor microenvironment, which plays a critical role in tumor growth, invasion, spreading, metastasis, angiogenesis, inhibition of anoikis, and chemoresistance. Fibroblasts, myofibroblasts and activated stellate cells produce the extracellular matrix components and are thought to interact actively with tumor cells, thereby promoting cancer progression. In this review, we discuss our current understanding of the role of pancreatic stellate cells (PSC) in the desmoplastic response of pancreas cancer and the effects of PSC on tumor progression, metastasis and drug resistance. Finally we present some novel ideas for tumor therapy by interfering with the cancer cell-host interaction.

Molecular and cellular mechanisms of pancreatic injury

PURPOSE OF REVIEW

This review focuses on studies from the past year that highlight molecular and cellular mechanisms of pancreatic injury arising from acute and chronic pancreatitis.

RECENT FINDINGS

Factors that induce or ameliorate injury as well as cellular pathways involved have been examined. Causative or sensitizing factors include refluxed bile acids, hypercalcemia, ethanol, hypertriglyceridemia, and acidosis. In addition, the diabetes drug exendin-4 has been associated with pancreatitis, whereas other drugs may reduce pancreatic injury. The intracellular events that influence disease severity are better understood. Cathepsin-L promotes injury through an antiapoptotic effect, rather than by trypsinogen activation. In addition, specific trypsinogen mutations lead to trypsinogen misfolding, endoplasmic reticulum stress, and injury. Endogenous trypsin inhibitors and upregulation of proteins including Bcl-2, fibroblast growth factor 21, and activated protein C can reduce injury. Immune cells, however, have been shown to increase injury via an antiapoptotic effect.

SUMMARY

The current findings are critical to understanding how causative factors initiate downstream cellular events resulting in pancreatic injury. Such knowledge will aid in the development of targeted treatments for pancreatitis. This review will first discuss factors influencing pancreatic injury, and then conclude with studies detailing the cellular mechanisms involved.

Alcohol-induced acute pancreatitis: the 'critical mass' concept

The association of alcohol consumption and acute pancreatitis (AP) has been well documented. Extensive research in the field of alcohol-induced AP has allowed scientists to understand the different aspects by which ethanol may alter pancreatic cellular function. However, despite the recognition and understanding of these proposed mechanisms, the basic question that remains unanswered is that although alcohol is consumed the world over, why is it that only some people develop AP? Epidemiologic data indicates a higher frequency of alcohol-induced AP in geographical locations where surrogate/home-brewed alcoholic beverages are freely available. These surrogate/home-brewed alcoholic beverages contain in addition to ethanol, higher alcohols (e.g. propanol and butanol) and other by-products/contaminants (e.g. acids, aldehydes and esters), the potential of which to induce pancreatic damage has been incompletely studied. Mutations in genes that metabolise alcohol as well as those that protect the acinar cells and the extra-acinar milieu from prematurely activated digestive enzymes (e.g. genetic mutations in SPINK1 or PRSS1 genes) have also been noted in these geographical locations. Based on the available epidemiologic, clinical and basic research data available at the present time, we propose a unifying hypothesis presenting for the first time the 'critical mass' concept. We hypothesise that it is the achievement of a 'critical mass' of damaged acinar cells that is required to trigger off the inflammatory cascade leading to a clinically recognised attack of AP. The consequence of a critical mass of damaged acinar cells is the generation of sufficient mediators to result in clinical AP. While the consumption of alcohol does damage acinar cells, the number of damaged acinar cells does not necessarily reach the 'critical mass' with every binge. Co-factors such a high fat or protein meals are required to sensitize the acinar cells by raising the metabolic state to a high level which compromises the viability of the cells. In addition, the existence of genetic mutations and / or the consumption of surrogate alcoholic beverages, by facilitating acinar cell damage, directly or indirectly, potentially hasten the achievement of the 'critical mass', leading to an attack of AP.