Early events in acute pancreatitis

Toll-like receptor 4 in pancreatic damage and immune infiltration in acute pancreatitis

Acute pancreatitis is a complex inflammatory disease resulting in extreme pain and can result in significant morbidity and mortality. It can be caused by several factors ranging from genetics, alcohol use, gall stones, and ductal obstruction caused by calcification or neutrophil extracellular traps. Acute pancreatitis is also characterized by immune cell infiltration of neutrophils and M1 macrophages. Toll-like receptor 4 (TLR4) is a pattern recognition receptor that has been noted to respond to endogenous ligands such as high mobility group box 1 (HMGB1) protein and or exogenous ligands such as lipopolysaccharide both of which can be present during the progression of acute pancreatitis. This receptor can be found on a variety of cell types from endothelial cells to resident and infiltrating immune cells leading to production of pro-inflammatory cytokines as well as immune cell activation and maturation resulting in the furthering of pancreatic damage during acute pancreatitis. In this review we will address the various mechanisms mediated by TLR4 in the advancement of acute pancreatitis and how targeting this receptor could lead to improved outcomes for patients suffering from this condition.

Immune response mechanisms in acute and chronic pancreatitis: strategies for therapeutic intervention

Acute pancreatitis (AP) is one of the most common inflammatory diseases of the gastrointestinal tract and a steady rising diagnosis for inpatient hospitalization. About one in four patients, who experience an episode of AP, will develop chronic pancreatitis (CP) over time. While the initiating causes of pancreatitis can be complex, they consistently elicit an immune response that significantly determines the severity and course of the disease. Overall, AP is associated with a significant mortality rate of 1-5%, which is caused by either an excessive pro-inflammation, or a strong compensatory inhibition of bacterial defense mechanisms which lead to a severe necrotizing form of pancreatitis. At the time-point of hospitalization the already initiated immune response is the only promising common therapeutic target to treat or prevent a severe disease course. However, the complexity of the immune response requires fine-balanced therapeutic intervention which in addition is limited by the fact that a significant proportion of patients is in danger of development or progress to recurrent and chronic disease. Based on the recent literature we survey the disease-relevant immune mechanisms and evaluate appropriate and promising therapeutic targets for the treatment of acute and chronic pancreatitis.

The Impact of Pancreatic Exocrine Diseases on the β-Cell and Glucose Metabolism-A Review with Currently Available Evidence

Pancreatic exocrine and endocrine dysfunctions often come together in the course of pancreatic diseases as interdependent manifestations of the same organ. However, the mechanisms underlying the bidirectional connection of the exocrine and endocrine pancreas are not fully understood. In this review, we aimed to synthetize the current knowledge regarding the effects of several exocrine pancreatic pathologies on the homeostasis of β-cells, with a special interest in the predisposition toward diabetes mellitus (DM). We focused on the following pancreatic exocrine diseases: chronic pancreatitis, acute pancreatitis, cystic fibrosis, pancreatic cancer, pancreatic resections, and autoimmune pancreatitis. We discuss the pathophysiologic mechanisms behind the impact on β-cell function and evolution into DM, as well as the associated risk factors in progression to DM, and we describe the most relevant and statistically significant findings in the literature. An early and correct diagnosis of DM in the setting of pancreatic exocrine disorders is of paramount importance for anticipating the disease's course and its therapeutical needs.

Early continuous blood purification affects TNF-α, IL-1β, and IL-6 in patients with severe acute pancreatitis via inhibiting TLR4 signaling pathway

To exploit whether early continuous blood purification (CBP) inhibits the Toll-like receptors 4 (TLR4) signaling pathway in the peripheral blood of patients with severe acute pancreatitis (SAP) and whether it affects the abundance of inflammatory factors; 130 SAP patients were randomly selected and divided into Groups B and C. Both groups received conventional treatment. Among them, Group C was given early CBP treatment. Another 60 healthy cases in physical examination at the same time were selected as Group A. The abundances of TLR4 and inflammatory factors were detected before and after treatment. Compared with Group B, (1) the symptoms in Group C improved more markedly; (2) protein contents of TLR4 and nuclear factor kappa B (NF-κB) in Group C diminished more signally; (3) the abundances of tumor necrosis factor alpha (TNF-α), cytokine interleukin-1β (IL-1β), and cytokine interleukin 6 (IL-6) in Group C decreased (p < 0.05); and (4) the abundance of TLR4 in Group C was positively correlated with those of TNF-α, IL-1β, and IL-6 after treatment (all p < 0.001). Early CBP inhibits TLR4 signaling pathway in SAP patients and attenuates the abundance of inflammatory factors to a certain extent, which may provide a new clinical treatment strategy for SAP.

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.

New Risk Factors for Infected Pancreatic Necrosis Secondary to Severe Acute Pancreatitis: The Role of Initial Contrast-Enhanced Computed Tomography

BACKGROUND AND AIMS

Pancreatic necrosis is a risk factor for poor prognosis of acute pancreatitis (AP). However, the associations between the findings on initial contrast-enhanced computed tomography (CT) of the pancreas and infected pancreatic necrosis (IPN) are unclear.

METHODS

This was a retrospective cohort study. Patients with severe AP (SAP) from January 2014 to December 2016 at the First Affiliated Hospital of Nanchang University were enrolled and assigned to an IPN group and a non-IPN group. Univariate and multivariate logistic regression analyses were sequentially performed to assess the associations between the variables and IPN development. A receiver operating characteristic (ROC) curve was generated for the qualified independent risk factor.

RESULTS

Forty-two patients with IPN were compared with 100 patients without IPN. Contrast-enhanced CT was performed 7 (range 3-10) days after AP onset. Multivariate stepwise logistic regression analyses showed that the number of acute peripancreatic fluid collections (APFCs) (OR 1.328, P = 0.006), presence of peripancreatic and pancreatic parenchymal necrosis (OR 4.001, P = 0.001), and gastrointestinal wall thickening (OR 3.353, P = 0.006) were independent risk factors for IPN secondary to SAP. The area under an ROC curve for the number of APFCs was 0.714, the sensitivity was 78.60%, and the specificity was 57.30% at a cutoff value of 4.5.

CONCLUSIONS

The number of APFCs, presence of peripancreatic and pancreatic parenchymal necrosis, and gastrointestinal wall thickening were independent risk factors associated with IPN. As initial contrast-enhanced CT (about 7 days from AP onset) plays an important role in predicting IPN, it is important for clinicians to consider initial imaging of the pancreas.

The effect of selective serotonin re-uptake inhibitors on risk of type II diabetes mellitus and acute pancreatitis: a meta-analysis

To explore the effect of selective serotonin re-uptake inhibitors (SSRIs) on risk of type II diabetes mellitus (T2DM) and acute pancreatitis (AP), expecting to provide guidance for clinic. Literature was retrieved by searching Pubmed, Embase, Cochrane and Scopus and hand searching of reference lists of related articles. Stata 14.0 was utilized for processing and analysis, and adjusted odds ratios (aORs) were applied. Our study included 113898 T2DM patients and 284131 controls from nine studies and 17548 AP patients and 108108 controls from four studies. The pooled aORs of SSRIs on the risk of T2DM and AP were 1.38 (95% confidence interval (CI) = 1.24–1.54) and 1.26 (95% CI = 1.13–1.40), respectively. Study design, quality, ethnicity, follow-up, and sample size of patients were the resources of heterogeneity. Subgroup analysis showed that 2 weeks is a high-risk time for AP after SSRIs use, with 1.48-fold-times as much after it. This meta-analysis provides evidence of a significant positive association between SSRIs use and risks of T2DM or AP, and duration of 2 weeks of SSRIs use has higher risk of AP, which should be paid much attention to.

Diabetes Mellitus is Associated With Mortality in Acute Pancreatitis

BACKGROUND AND AIM

Predicting severe pancreatitis is important for early aggressive management of patients with acute pancreatitis (AP). Despite the established role of diabetes mellitus (DM) in the risk of AP, the impact of DM on the clinical outcome in AP has not been fully elucidated. The objective of this study was to assess the risk of mortality and severity in AP among patients with type-2 DM.

METHODS

Patients diagnosed with first attacks of AP were enrolled from January 2013 to June 2015.

RESULTS

A total of 201 patients (63.2% male, mean age, 59.4 y) with AP were included. Etiologies included gallstones (51.2%), alcohol (37.3%), hypertriglyceridemia (2%), and idiopathic causes (9.5%). There were 54 AP patients (26.9%) with type-2 DM. Severity indices in AP, such as Atlanta Classification (severe), Ranson score, and Bedside Index of Severity in Acute Pancreatitis, were higher in subjects with DM than those without DM. Prevalence of intensive care unit admission and mortality were higher in AP patients with DM compared with those without DM. The association between DM and increased risk of mortality in AP remained statistically significant even after adjustments for confounding factors and Atlanta Classification (odds ratio, 7.76, 95% confidence interval, 1.26-47.63, P=0.027).

CONCLUSIONS

Type-2 DM was associated with severity and increased mortality in patients with AP. Our findings provide evidence of the potential role of DM in the pathogenesis and management of severe AP.

Astaxanthin ameliorates cerulein-induced acute pancreatitis in mice

BACKGROUND

A various of pharmacological effects of astaxanthin has been confirmed. However, the mechanism underlying protective effect of astaxanthin on acute pancreatitis (AP) induced by cerulein still unclear. The present study is to investigate the mechanism underlying the effect of astaxanthin on autophagy and apoptosis via the JAK/STAT3 pathway.

METHODS

Intraperitoneal injection of cerulein at hourly intervals followed by lipopolysaccharide injection were used in Balb/C mice. Vehicle or astaxanthin, which intraperitoneal injected in two doses (20 mg/kg and 40 mg/kg), were injected in mice 1 h before the first cerulein injection. At 3 h after the last injection, when the pathological changes were most severe, pancreatic tissue was analyzed by pathologically scored and hematoxylin and eosin (H&E) staining. The severity of AP was assessed by histological grading, proinflammatory cytokine levels, biochemistry, myeloperoxidase (MPO) activity, and analysis of JAK/STAT3 activity.

RESULTS

Astaxanthin administration markedly reduced serum digestive enzyme activities, pancreatic histological scores, proinflammatory cytokine levels (tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), and Interleukin-6 (IL-6)), MPO and JAK/STAT3 activity.

CONCLUSION

Collectively, these results indicate that astaxanthin inhibits pancreatic injury in AP by targeting JAK/STAT3-mediated apoptosis and autophagy.

The Prognosis of Severe Acute Pancreatitis Varies According to the Segment Presenting With Low Enhanced Pancreatic Parenchyma on Early Contrast-Enhanced Computed Tomography: A Multicenter Cohort Study

OBJECTIVE

The aim of this study was to investigate the outcomes of severe acute pancreatitis (SAP) according to the segment presenting with low enhanced pancreatic parenchyma (LEPP) on early contrast-enhanced computed tomography.

METHODS

This was a post hoc analysis of a multicenter, retrospective study conducted at 44 institutions in Japan. Patients diagnosed as having SAP according to the Japanese Severity Score between January 2009 and December 2013 were included. We compared the effect of LEPP in each segment on mortality.

RESULTS

A total of 1097 patients were assessed. The numbers of patients with LEPP in the pancreatic head (Ph), body (Pb), or tail (Pt) were 272, 273, and 204 (with some overlaps), respectively. In multivariate analysis, LEPP in Ph and Pt was significantly related to mortality (odds ratio [OR], 1.94; 95% confidence interval [CI], 1.11-3.40 [P < 0.05], for LEPP in Ph; OR, 2.44; 95% CI, 1.27-4.67 [P < 0.05], for LEPP in Pt), but LEPP in Pb was unrelated to mortality (OR, 0.70; 95% CI, 0.35-1.37; P = 0.30).

CONCLUSIONS

Presence of LEPP in Ph and Pt on early contrast-enhanced computed tomography was independently associated with increased mortality in SAP. These patients require close observation to ensure timely and adequate intervention.

Propylene Glycol Alginate Sodium Sulfate Alleviates Cerulein-Induced Acute Pancreatitis by Modulating the MEK/ERK Pathway in Mice

Previous studies have focused on the effects of propylene glycol alginate sodium sulfate  (PSS)  against  thrombosis,  but  the  anti-inflammatory  potential  is  unknown.  Therefore,  we  specifically focused on the protective effects of PSS on cerulein-induced acute pancreatitis (AP)  using a mouse model, and investigated the mechanism of PSS on autophagy and apoptosis via the  Mitogen-activated  protein  kinase  (MEK)/extracellular  signal-regulated  kinase  (ERK)  pathway.  Cerulein (100 ug/kg) was used to induce AP by ten intraperitoneal injections at hourly intervals in  Balb/C mice. Pretreatment with vehicle or PSS was carried out 1 h before the first cerulein injection  and two doses (25 mg/kg and 50 mg/kg) of PSS were injected intraperitoneally. The severity of AP was  assessed by pathological score, biochemistry, pro-inflammatory cytokine levels, myeloperoxidase  (MPO) activity and MEK/ERK activity. Furthermore, pancreatic histological scores, serum amylase  and lipase activities, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β interleukin (IL)-6 levels, and  MPO activity were significantly reduced by PSS via up-regulated MEK/ERK activity. The representative  molecules of apoptosis and autophagy, such as Bcl-2, Bax, Lc-3, Beclin-1, P62, were remarkably reduced.  Taken together, these results indicate that PSS attenuates pancreas injury by inhibiting autophagy and  apoptosis through a mechanism involving the MEK/ERK signaling pathway.

Bidirectional Relationship Between Diabetes and Acute Pancreatitis: A Population-Based Cohort Study in Taiwan

The proposed bidirectional relationship between acute pancreatitis (AP) and diabetes has never been examined with the same source of data. Furthermore, the effects of disease severity on this relationship have not been fully evaluated. The present study employed the findings from a single database to measure the strength of the association between AP and diabetes.Findings from 1 million National Health Insurance beneficiaries were utilized. Two cohort studies with this database were selected to evaluate the linkage between diabetes and AP. The first cohort analysis addressed the risk of AP among diabetic patients and was comprised of 42,080 diabetic patients and 672,146 unexposed subjects. The second cohort analysis considered the risk of diabetes among patients with AP and enrolled 3187 patients with AP and 709259 unexposed subjects. All adult beneficiaries were followed from January 1, 2005 to December 31, 2012 to identify outcomes of interest. Cox regression models were applied to compare hazards adjusted for potential confounders.For the first cohort, the adjusted hazard ratio (HR) of AP was significantly increased by the presence of diabetes (1.72; 95% confidence interval [CI], 1.52-1.96). In diabetic patients with a history of hyperglycemic crisis episodes (HCEs), the HR was even higher (6.32; 95% CI, 4.54-8.81). For the second cohort, the adjusted HR of diabetes in patients with AP was increased compared to the general population (2.15; 95% CI, 1.92-2.41). For patients with severe AP, the HR was also higher (2.22; 95% CI, 1.50-3.29) but did not differ significantly from that for patients with nonsevere AP.The 2 cohort studies provided evidence for the bidirectional relationship between diabetes and AP. Moreover, diabetic patients with history of HCEs may be associated with higher risk of AP.

Oxidative stress in acute pancreatitis: lost in translation?

Oxidative stress has been implicated in the pathogenesis of acute pancreatitis, a severe and debilitating inflammation of the pancreas that carries a significant mortality, and which imposes a considerable financial burden on the health system due to patient care. Although extensive efforts have been directed towards the elucidation of critical underlying mechanisms and the identification of novel therapeutic targets, the disease remains without a specific therapy. In experimental animal models of acute pancreatitis, increased oxidative stress and decreased antioxidant defences have been observed, changes also detected in patients clinically. However, despite the promise of studies evaluating the effects of antioxidants in these model systems, translation to the clinic has thus far been disappointing. This may reflect many factors involved in the design of both preclinical and clinical evaluations of antioxidant therapy, not least the fact that most experimental studies have focussed on pre-treatment rather than post-injury assessment. This review has examined evidence relating to the involvement of oxidative stress in the pathophysiology of acute pancreatitis, focussing on experimental models and the clinical experience, including the experimental techniques employed and potential of antioxidant therapy.

Extrapancreatic necrosis without pancreatic parenchymal necrosis: a separate entity in necrotising pancreatitis?

OBJECTIVE

In the revised Atlanta classification of acute pancreatitis, the term necrotising pancreatitis also refers to patients with only extrapancreatic fat necrosis without pancreatic parenchymal necrosis (EXPN), as determined on contrast-enhanced CT (CECT). Patients with EXPN are thought to have a better clinical outcome, although robust data are lacking.

METHODS

A post hoc analysis was performed of a prospective multicentre database including 639 patients with necrotising pancreatitis on contrast-enhanced CT. All CECT scans were reviewed by a single radiologist blinded to the clinical outcome. Patients with EXPN were compared with patients with pancreatic parenchymal necrosis (with or without extrapancreatic necrosis). Outcomes were persistent organ failure, need for intervention and mortality. A predefined subgroup analysis was performed on patients who developed infected necrosis.

RESULTS

315 patients with EXPN were compared with 324 patients with pancreatic parenchymal necrosis. Patients with EXPN less often suffered from complications: persistent organ failure (21% vs 45%, p<0.001), persistent multiple organ failure (15% vs 36%, p<0.001), infected necrosis (16% vs 47%, p<0.001), intervention (18% vs 57%, p<0.001) and mortality (9% vs 20%, p<0.001). When infection of extrapancreatic necrosis developed, outcomes between groups were equal (mortality with infected necrosis: EXPN 28% vs pancreatic necrosis 18%, p=0.16).

CONCLUSION

EXPN causes fewer complications than pancreatic parenchymal necrosis. It should therefore be considered a separate entity in acute pancreatitis. Outcome in cases of infected necrosis is similar.

Deletion of IκBα activates RelA to reduce acute pancreatitis in mice through up-regulation of Spi2A

BACKGROUND & AIMS

The transcription factor nuclear factor-κB (NF-κB) (a heterodimer of NF-κB1p50 and RelA) is activated rapidly in acute pancreatitis (AP). However, it is not clear whether NF-κB promotes or protects against AP. We used the NF-κB inhibitor protein, inhibitor of κB (IκB)α, to study the roles of NF-κB in the development of AP in mice.

METHODS

IκBα or the combination of IκBα and RelA selectively were deleted from pancreas of mice using the Cre/locus of cross-over P strategy; cerulein or L-arginine were used to induce AP. We performed microarray analyses of the IκBα- and RelA-deficient pancreata. DNA from healthy individuals and patients with acute or chronic pancreatitis were analyzed for variants in coding regions of alpha-1-antichymotrypsin.

RESULTS

Mice with pancreas-specific deletion of IκBα had constitutive activation of RelA and a gene expression profile consistent with NF-κB activation; development of AP in these mice was attenuated and trypsin activation was impaired. However, AP was fully induced in mice with pancreas-specific deletion of IκBα and RelA. By using genome-wide expression analysis, we identified a cluster of NF-κB-regulated genes that might protect against the development of AP. The serine protease inhibitor 2A (Spi2a) was highly up-regulated in IκBα-deficient mice. Lentiviral-mediated expression of Spi2A reduced the development of AP in C57BL/6 and RelA-deficient mice. However, we did not correlate any variants of alpha-1-antichymotrypsin, the human homologue of Spi2a, with acute or chronic pancreatitis.

CONCLUSIONS

Pancreas-specific deletion of IκBα results in nuclear translocation of RelA and reduces AP induction and trypsin activation in mice after administration of cerulein or L-arginine. Constitutive activation of RelA up-regulates Spi2A, which protects mice against the development of AP.

Prevention of severe acute pancreatitis with octreotide in obese patients: a prospective multi-center randomized controlled trial

OBJECTIVES

To evaluate the efficacy of octreotide in preventing severe acute pancreatitis (SAP) in obese patients.

METHODS

A prospective multi-center partly randomized control trial was conducted in patients with mild acute pancreatitis (AP). Nonobese patients received conventional management (nonobese-C, n = 82), whereas obese patients (body mass index ≥ 25 kg/m(2)) were randomized into 2 groups: obese-C (n = 79), who received conventional management, and obese-C+O (n = 82), who received conventional management plus intravenous infusion of octreotide, 50 μg/h for 72 hours.

RESULTS

The risk ratio and relative risk reduction in the development of SAP in the obese-C+O group were 0.27 (95% confidence interval, 0.10-0.69) and 0.73 (95% confidence interval, 0.31-0.90), respectively. The number of cases developing local complications in the obese-C+O group was significantly smaller than that in the obese-C group: 4.9% vs 19%, P = 0.006. The plasma level of somatostatin in the obese-C+O group was significantly higher than that in the obese-C group: 165.5 ± 42.6 vs 112.1 ± 24.86 pg/mL, P < 0.05. Supplement of octreotide also accompanied with reduction in plasma levels of tumor necrosis factor α and IL-6.

CONCLUSIONS

Intravenous administration of octreotide (50 μg/h) for 72 hours in the early stage of AP could prevent the development of SAP effectively in obese patients by raising plasma somatostatin to a normal level and reducing circulating cytokines.

Raf-1 kinase inhibitory protein (RKIP) mediates ethanol-induced sensitization of secretagogue signaling in pancreatic acinar cells

Excessive alcohol consumption is associated with most cases of chronic pancreatitis, a progressive necrotizing inflammatory disease that can result in pancreatic insufficiency due to acinar atrophy and fibrosis and an increased risk of pancreatic cancer. At a cellular level acute alcohol exposure can sensitize pancreatic acinar cells to secretagogue stimulation, resulting in dysregulation of intracellular Ca(2+) homeostasis and premature digestive enzyme activation; however, the molecular mechanisms by which ethanol exerts these toxic effects have remained undefined. In this study we identify Raf-1 kinase inhibitory protein as an essential mediator of ethanol-induced sensitization of cholecystokinin- and carbachol-regulated Ca(2+) signaling in pancreatic acinar cells. We show that exposure of rodent acinar cells to ethanol induces protein kinase C-dependent Raf-1 kinase inhibitory protein phosphorylation, sensitization of cholecystokinin-stimulated Ca(2+) signaling, and potentiation of both basal and cholecystokinin-stimulated extracellular signal-regulated kinase activation. Furthermore, we show that either suppression of Raf-1 kinase inhibitory protein expression using short hairpin RNA or gene ablation prevented the sensitizing effects of ethanol on cholecystokinin- and carbachol-stimulated Ca(2+) signaling and intracellular chymotrypsin activation in pancreatic acinar cells, suggesting that the modulation of Raf-1 inhibitory protein expression may have future therapeutic utility in the prevention or treatment of alcohol-associated pancreatitis.

Acute pancreatitis due to diabetes: the role of hyperglycaemia and insulin resistance

BACKGROUND

The co-existence of diabetes mellitus (DM) in patients with acute pancreatitis (AP) is linked to poor outcomes. Four large epidemiological studies have suggested an aetiological role for DM in AP. The exact nature of this role is poorly understood.

OBJECTIVE

To analyse the available clinical and experimental literature to determine if DM may play a causative role in AP.

METHODS

A systematic search of the scientific literature was carried out using EMBASE, PubMed/MEDLINE, and the Cochrane Central Register of Controlled Trials for the years 1965-2011 to obtain access to all publications, especially randomized controlled trials, systematic reviews, and meta-analyses exploring the mechanisms of pathogenesis of AP in patients with DM.

RESULTS

No clinical studies could be identified directly providing pathogenetic mechanisms of DM in the causation of AP. The available data on DM and its associated metabolic changes and therapy indicate that hyperglycaemia coupled with the factors influencing insulin resistance (tumour necrosis-α, NFκB, amylin) cause an increase in reactive oxygen species generation in acinar cells.

CONCLUSIONS

Complex pathogenetic connections exist between AP and factors involved in the development and therapy of DM. Insulin resistance and hyperglycaemia, hallmarks of DM, are important factors linked to the susceptibility of diabetics to AP. Given the high morbidity associated with an attack of AP in a diabetic patient, targeting these two aspects by therapy may help not only to reduce the risk of development of AP, but may also help reduce the severity of an established attack in a diabetic patient.

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

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

[The clinical relevance of experimental acute pancreatitis models]

The clinical diagnostics and therapeutic standards applied in the routine management of human acute pancreatitis are based on the results of animal experiments and human studies performed in the past several decades. During this time period, a number of experimental acute pancreatitis models have been developed, which allowed us to study the etiopathogenesis of acute pancreatitis, analyzing the local and remote complications of the inflammatory processes and also the preclinical testing of potentially effective drugs and agents. Only animal models are suitable to examine the very early phase of the pathogenetic processes in acute pancreatitis. In recent years, the progress in molecular genetic methods allowed us to create genetically engineered animal models to clarify the role of different mediators in the pathogenetic process. There is no doubt that the results gained from experimental animal studies are of limited value concerning human pancreatitis. Nevertheless, experimental studies seem to be indispensable in the progress of management of human pancreatic disorders.

[Changes in diagnostic and therapeutic standards of acute pancreatitis in clinical practice. Epidemiologic analysis of data from a regional center of internal medicine and surgery]

Epidemiological data analysis of a tertiary (regional) medical and surgical center. Diagnostic and therapeutic standards of patients with acute pancreatitis have changed significantly in the last few decades. Progress in laboratory and imaging diagnostics and achievements in experimental research resulted in a significant modification of the guidelines related to the care of pancreatitic patients. The aim was to analyse and compare the data of patients with acute pancreatitis treated in 1996 (period I) and 2004 (period II) at the Departments of Internal Medicine and Surgery, University of Szeged, to evaluate the concordance with international guidelines during medical and surgical treatment.

RESULTS

The authors analysed the clinical data of 126 and 124 patients, respectively, with acute pancreatitis observed during the two periods. An increase in the incidence of biliary acute pancreatitis, more frequent use of antibiotics, a higher frequency of therapeutic endoscopies (papillotomy and biliary stone extraction), the general application of ultrasonography-guided fine needle aspiration and bacterial culturing in cases of suspected infected necrosis, and higher effectiveness in complex surgical and supportive management of infected necrosis cases were detected in period II.

CONCLUSION

Although most of the achievements suggested in international guidelines on medical/endoscopic and surgical treatment of acute pancreatitis have been implemented during the observation period, no significant changes in the morbidity and mortality data of patients were found.

Experimental model of severe acute pancreatitis in rabbits

PURPOSE: To develop an experimental model of severe acute pancreatitis in rabbits through a pancreatic ductal injection of sodium taurocholate. METHODS: Twenty-four albino rabbits of the New Zealand lineage were distributed into four groups of six animals (A, B, C and S). The rabbits of three experimental groups (A, B and C) were submitted to a laparatomy and received a pancreatic ductal injection of 1ml/kg sodium taurocholate 5%. Also, they were submitted to further laparatomies after 4h, 8h and 12h, respectively. The control group (S) was subdivided into two groups of three animals: in subgroup S1 only the pancreatic duct catheterization was performed whereas in subgroup S2 the pancreatic duct catheterization as well as an injection of 1ml/kg physiologic solution 0.9% were carried out. After 12 hours, the rabbits were evaluated. In the re-intervention, blood was collected to determine the amylasemia and a pancreatectomy was carried out to investigate interstitial infiltration, steatonecrosis and necrosis of the organ, using an optical microscope. RESULTS: There was an elevation of amylase in all groups thus proving the existence of acute pancreatitis. The size of the interlobular septum increased progressively with a greater variation between group S1 (0.13) and group C (0. 53) (p=0.035). While all the animals in group A exhibited focal cellular necrosis, it was more intense in the rabbits of group B and culminated with a high proportion of severe pancreatic necrosis in group C animals. The difference in the intensity of cellular necrosis showed statistic significance (p=0.001). CONCLUSION: The proposed experimental model demonstrated its reproducibility and effectiveness in producing severe acute pancreatitis in rabbits.

[Inflammatory pancreatic disease due to enzyme autodigestion: an exceptional model of glandular crinophagy]

The exocrine pancreas is a functionally dangerous structure since it is exposed to digestion by its most aggressive enzymes (proteases, etc) despite self-protective measures such as the synthesis of some of these enzymes in the form of inactive zymogens (trypsinogen, etc.). We review inflammatory pancreatic disease by separately analyzing its classical forms of onset: acute and chronic pancreatitis (AP and CP). There is general consensus that the initial pathogenic event in AP is intraacinar activation of trypsinogen into trypsin, followed by that of the remaining proenzymes, giving rise to an unusual model of autophagic inflammation. In contrast, consensus is lacking on the initial pathogenic event in CP (toxic-metabolic lesion, oxidative stress, ductal hypertension, etc.?), although in some cases a <<necrosis-fibrosis>> sequence due to recurrent episodes of AP seems evident. The pathogenic features shared by both forms of the disease and which justify some recent attempts to formulate an overall explanation of the pathogenesis of pancreatitis are discussed. Such an explanation would place both forms of pancreatitis within the conceptual framework of an <<inflammatory pancreatic disease due to enzyme autodigestion>>.

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

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

K+-induced ion-exchanges trigger trypsin activation in pancreas acinar zymogen granules

Trypsin premature activation has been thought to be a key event in the initiation phase of acute pancreatitis. Here we test a hypothesis that a sustained increase of cytosolic Ca(2+) concentration ([Ca(2+)](C)) can trigger K(+) influx into pancreas acinar zymogen granules (ZGs) via a Ca(2+)-activated K(+) channel (K(Ca)), and this influx of K(+) then mobilizes bound-Ca(2+) by K(+)/Ca(2+) ion-exchange to increase free Ca(2+) concentration in the ZGs ([Ca(2+)](G)) and release bound-H(+) by K(+)/H(+) ion-exchange to decrease the pH in ZGs (pH(G)). Both the increase of [Ca(2+)](G) and the decrease of pH(G) will facilitate trypsinogen autoactivation and stabilize active trypsin inside ZGs that could lead to acute pancreatitis. The experimental results are consistent with our hypothesis, suggesting that K(+) induced ion-exchanges play a critical role in the initiation of trypsin premature activation in ZGs.

Ethanol augments elevated-[Ca2+]C induced trypsin activation in pancreatic acinar zymogen granules

It has been long recognized that significant percentage of patients with acute pancreatitis often presents with a history of excessive alcohol consumption; however, the patho-physiological effect of ethanol on acute pancreatitis remains poorly understood. Abnormally elevated cytosolic Ca2+ ([Ca2+]C) has been found to be a shared phenomenon in acute pancreatitis that could induce trypsin premature activation. Here, we present the effects of ethanol to sensitize zymogen granules (ZGs) of pancreas acinar cells to elevated [Ca2+]C leading to zymogen premature activation that could result in acute pancreatitis. The pH fluctuations ([pH]G), Ca2+ concentration ([Ca2+]G), and premature trypsin activation inside the ZGs were monitored directly with specific fluorescence indicators. Our results showed that ethanol could act directly on ZGs and cause ZGs more receptive to elevated [Ca2+]C that could induce premature activation of zymogen (trypsin). This alcohol-induced effect is concentration dependent and strongly influenced by the surrounding [Ca2+]C. The K+ channels on ZGs membranes are required in the sensitization process. Our observations provide a mechanistic understanding of the role of ethanol in the initiation phase of alcoholic pancreatitis.

Free radicals and the pancreatic acinar cells: role in physiology and pathology

Reactive oxygen and nitrogen species (ROS and RNS) play an important role in signal transduction and cell injury processes. Nitric oxide synthase (NOS)-the key enzyme producing nitric oxide (NO)-is found in neuronal structures, vascular endothelium and, possibly, in acinar and ductal epithelial cells in the pancreas. NO is known to regulate cell homeostasis, and its effects on the acinar cells are reviewed here. ROS are implicated in the early events within the acinar cells, leading to the development of acute pancreatitis. The available data on ROS/RNS involvement in the apoptotic and necrotic death of pancreatic acinar cells will be discussed.

Trypsinogen mutations in pancreatic disorders

There are multiple PRSS1 mutations described in hereditary pancreatitis but only a minority of these are clinically relevant. The two most frequent point mutations are in exon 2 (N29I) and exon3 (R122H), found in diverse racial populations. Both mutations result in early onset pancreatitis but the mechanism underlying this phenotype is unclear. The frequency of these mutations in such diverse populations suggests they have spontaneously occurred many times. The origin of the major mutations may be explained by gene conversions, accounting for multiple founders. The implications are discussed in terms of mechanism of action of the mutations and clinical presentation.