Peripancreatic fat necrosis worsens acute pancreatitis independent of pancreatic necrosis via unsaturated fatty acids increased in human pancreatic necrosis collections

NF-κB in acute pancreatitis: Mechanisms and therapeutic potential

The incidence of acute pancreatitis (AP) is increasing globally and mortality could be high among patients with organ failure and infected necrosis. The predominant factors responsible for the morbidity and mortality of AP are systemic inflammatory response syndrome and multiorgan dysfunction. Even though preclinical studies have shown antisecretory agents (somatostatin), antioxidants (S-adenosyl methionine [SAM], selenium), protease inhibitors, platelet activating factor inhibitor (Lexipafant), and anti-inflammatory immunomodulators (eg. prostaglandin E, indomethacin) to benefit AP in terms of reducing the severity and/or mortality, most of these agents have shown heterogeneous results in clinical studies. Several years of experimental studies have implicated nuclear factor-kappa B (NF-κB) activation as an early and central event in the progression of inflammation in AP. In this manuscript, we review the literature on the role of NF-κB in the pathogenesis of AP, its early intraacinar activation, and how it results in progression of the disease. We also discuss why anti-protease, antisecretory, and anti-inflammatory agents are unlikely to be effective in clinical acute pancreatitis. NF-κB, being a central molecule that links the initial acinar injury to systemic inflammation and perpetuate the inflammation, we propose that more studies be focussed towards targeted inhibition of NF-κB activity. Direct NF-κB inhibition strategies have already been attempted in patients with various cancers. So far, peroxisome proliferator activator receptor gamma (PPAR-γ) ligand, pyrrolidine dithiocarbamate (PDTC), proteasome inhibitor and calpain I inhibitor have been shown to have direct inhibitory effects on NF-κB activation in experimental AP.

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.

Characterization and Predictive Value of Near Infrared 2-Deoxyglucose Optical Imaging in Severe Acute Pancreatitis

Background

Studying the uptake of 2-deoxy glucose (2-DG) analogs such as 2-Deoxy-2-[18F] fluoroglucose (FDG) is a common approach to identify and monitor malignancies and more recently chronic inflammation. While pancreatitis is a common cause for false positive results in human studies on pancreatic cancer using FDG, the relevance of these findings to acute pancreatitis (AP) is unknown. FDG has a short half-life. Thus, with an aim to accurately characterize the metabolic demand of the pancreas during AP in real-time, we studied the uptake of the non-radioactive, near infrared fluorescence labelled 2-deoxyglucose analog, IRDye^® 800CW 2-DG probe (NIR 2-DG; Li-Cor) during mild and severe biliary AP.

Methods

Wistar rats (300 g; 8–12/group) were administered NIR 2-DG (10 nM; I.V.). Mild and severe biliary AP were respectively induced by biliopancreatic duct ligation (DL) alone or along with infusing glyceryl trilinoleate (GTL; 50 μL/100 g) within 10 minutes of giving NIR 2-DG. Controls (CON) only received NIR 2-DG. Imaging was done every 5–10 minutes over 3 hrs. Average Radiant Efficiency [p/s/cm²/sr]/[μW/cm²] was measured over the pancreas using the IVIS 200 in-vivo imaging system (PerkinElmer) using the Living Image^® software and verified in ex vivo pancreata. Blood amylase, lipase and pancreatic edema, necrosis were measured over the course of AP.

Results

NIR 2-DG uptake over the first hour was not influenced by AP induction. However, while the signal declined in controls and rats with mild AP, there was significantly higher retention of NIR 2-DG in the pancreas after 1 hour in those with GTL pancreatitis. The increase was > 3 fold over controls in the GTL group and was verified to be in the pancreas ex vivo. In vitro, pancreatic acini exposed to GTL had a similar increase in NIR 2-DG uptake which was followed by progressively worse acinar necrosis. Greater retention of NIR 2-DG in vivo was associated with worse pancreatic necrosis, reduced ATP concentrations and mortality, which were not predicted by the blood parameters.

Conclusion

In-vivo fluorescent imaging of a non-radioactive near infrared 2-DG optical probe can predict the AP severity early during the disease.

Fatty Acid Ethyl Esters Are Less Toxic Than Their Parent Fatty Acids Generated during Acute Pancreatitis

Although ethanol causes acute pancreatitis (AP) and lipolytic fatty acid (FA) generation worsens AP, the contribution of ethanol metabolites of FAs, ie, FA ethyl esters (FAEEs), to AP outcomes is unclear. Previously, pancreata of dying alcoholics and pancreatic necrosis in severe AP, respectively, showed high FAEEs and FAs, with oleic acid (OA) and its ethyl esters being the most abundant. We thus compared the toxicities of FAEEs and their parent FAs in severe AP. Pancreatic acini and peripheral blood mononuclear cells were exposed to FAs or FAEEs in vitro. The triglyceride of OA (i.e., glyceryl tri-oleate) or OAEE was injected into the pancreatic ducts of rats, and local and systemic severities were studied. Unsaturated FAs at equimolar concentrations to FAEEs induced a larger increase in cytosolic calcium, mitochondrial depolarization, and necro-apoptotic cell death. Glyceryl tri-oleate but not OAEE resulted in 70% mortality with increased serum OA, a severe inflammatory response, worse pancreatic necrosis, and multisystem organ failure. Our data show that FAs are more likely to worsen AP than FAEEs. Our observations correlate well with the high pancreatic FAEE concentrations in alcoholics without pancreatitis and high FA concentrations in pancreatic necrosis. Thus, conversion of FAs to FAEE may ameliorate AP in alcoholics.

Case-fatality from acute pancreatitis is decreasing but its population mortality shows little change

BACKGROUND/OBJECTIVES

The reasons for changing epidemiology of acute pancreatitis (AP) are poorly defined. We hypothesized that trends for severity, case-fatality and population mortality from AP will provide an insight into the rising burden of AP in the population. We evaluated trends in the hospitalizations, case-fatality, severity and population mortality related to AP in the US population.

STUDY

We used the National Hospital Discharge Survey to calculate age, sex and race standardized hospitalizations of and case-fatality rates for AP, and Vital Statistics to calculate AP-related population mortality from 1983 to 2010, using 2010 US census as the reference.

RESULTS

Number of discharges per 100,000 population with primary diagnosis of AP increased 2 times from 42.4 (95% CI 38.2-46.5) during 1983-1986 to 85.4 (95% CI 62.8-108.1) during 2007-2010. During corresponding intervals, case-fatality from AP decreased 62% from 2.02% (95% CI 2.01-2.04) to 0.79% (95% CI 0.78-0.80), but population mortality per million population due to AP as primary cause remained stable from 9.28 (95% CI 8.94-9.62) to 9.91 (95% CI 9.56-10.26), and from AP as any cause decreased significantly (but only 12%) from 20.87 (95% CI 20.36-21.38) to 18.48 (95% CI 18.00-18.96). Prevalence of severe AP increased from 5% (95% CI 4.95-5.05%) during 1991-1994 to 9.78% (95% CI 9.73-9.83%) during 2007-2010.

CONCLUSION

An increasing prevalence of severe disease suggests true population increase to be an important contributor to the rising incidence of AP. A lack of proportional increase in population mortality suggests the impact of medical advances in the evaluation and management of AP.

Elevated serum triglycerides are independently associated with persistent organ failure in acute pancreatitis

OBJECTIVES

Hypertriglyceridemia (HTG) represents a major health problem with prevalence exceeding 30% in the U.S. The present study aims to assess the effect of elevated serum triglyceride (TG) levels on the severity of acute pancreatitis (AP).

METHODS

Prospectively enrolled AP patients were categorized into normal, mild, moderate, and severe/very severe categories based on their TG levels and compared in respect to demographics, comorbidities, and clinical outcomes. Multivariate analysis determined whether elevated TG levels were independently associated with persistent organ failure.

RESULTS

Two hundred and one out of 400 AP patients had serum TGs measured within 72 h of presentation, of which 115 had normal TG levels and 86 HTG (20 mild, 41 moderate, and 25 severe/very severe). Patients with HTG were of younger age (44 vs. 52 years), predominantly male (65% vs. 45%), obese (57% vs. 34%), diabetic (38% vs. 17%), and developed more frequently persistent organ failure (40% vs. 17%) compared with those with normal TGs (P<0.02). The rate of persistent organ failure increased proportionally with HTG severity grades (17% when normal TGs, 30% in mild, 39% in moderate, and 48% in severe/very severe HTG, Ptrend<0.001). On multivariate analysis controlling for age, gender, body mass index, diabetes, and alcohol etiology, moderate HTG (odds ratio (OR), 2.6; P=0.04) and severe/very severe HTG (OR, 4.9; P=0.009) were independently associated with persistent organ failure.

CONCLUSIONS

Elevated serum TGs in AP patients are independently and proportionally correlated with persistent organ failure regardless of etiology. TG-mediated lipotoxicity may be an attractive target to design novel interventions for severe AP.

Central role of neutrophil in the pathogenesis of severe acute pancreatitis

Severe acute pancreatitis (SAP) is an acute abdominal disease with the strong systemic inflammatory response, and rapidly progresses from a local pancreatic damage into multiple organ dysfunction. For many decades, the contributions of neutrophils to the pathology of SAP were traditionally thought to be the chemokine and cytokine cascades that accompany inflammation. In this review, we focus mainly on those recently recognized aspects of neutrophils in SAP processes. First, emerging evidence suggests that therapeutic interventions targeting neutrophils significantly lower tissue damage and protect against the occurrence of pancreatitis. Second, trypsin activation promotes the initial neutrophils recruitment into local pancreas, and subsequently neutrophils infiltration in turn triggers trypsin production. Finally, neutrophils have the unique ability to release neutrophil extracellular traps even in the absence of pathogens.

Effect of different doses of quercetin on pancreatic pathology in rats with hypertriglyceridemia related acute pancreatitis

AIM: To investigate the effect of different doses of quercetin on the pancreatic pathology in rats with cerulein-induced acute pancreatitis (AP) associated with hypertriglyceridemia (HTG).

METHODS: Seventy-two male SD rats were randomly divided into 12 groups: HTG group (n = 6, fed a high-fat diet for 2 wk: 77% normal chow + 3% cholesterol + 20% lard), HTG + AP group (n = 6, after 2 wk of a high-fat diet, AP was induced by peritoneal injection of 50 μg/kg cerulein twice at 1-h interval), HTG + AP + quercetin groups [n = 24, divided into 4 groups (6 rats each), quercetin (50, 100, 150, 200 mg/kg) was administered to rats by peritoneal injection after AP induction], normal blood lipid group (n = 6, fed normal chow for 2 wk), normal blood lipid + AP group (n = 6, after 2 wk of normal chow, AP was induced by peritoneal injection of 50 μg/kg cerulein twice at 1-h interval), normal blood lipid + AP + quercetin groups [n = 24, divided into 4 groups (6 rats each), quercetin (50, 100, 150, 200 mg/kg) was administered to rats by peritoneal injection after AP induction]. All rats were sacrificed 9 h after AP induction. Plasma levels of amylase were tested and the pathological changes of pancreatic tissues were observed.

RESULTS: After two weeks of a high-fat diet, serum levels of triglyceride and total cholesterol were much higher than those in rats given normal chow (P < 0.001). Compared with the normal blood lipid + AP group, plasma level of amylase was significantly higher (23670.00 U/L ± 2053.13 U/L vs 13136.00 U/L ± 3536.95 U/L) and pancreatic tissue injury was significantly more serious in the HTG + AP group (9.75 ± 0.94 vs 5.92 ± 1.32) (P = 0.022; P < 0.001). Quercetin intervention groups showed significantly lower levels of amylase and less serious pancreatic tissue injury; the effect was dose-dependent. This protective effect of quercetin was more obvious in the HTG + AP group than in the AP group (HTG + AP + 100, 150, 200 mg/kg quercetin group vs HTG + AP group total histopathological scores: P < 0.001 for all; normal blood lipid + AP + 100, 150, 200 mg/kg quercetin group vs normal blood lipid + AP group total histopathological scores: P = 0.084, P = 0.003, P < 0.001), particularly in acinar necrosis and inflammatory infiltration (HTG + AP + 100, 150, 200 mg/kg quercetin group vs HTG + AP group necrosis score: P < 0.001 for all; inflammatory infiltration: P = 0.008, P = 0.006, P = 0.001).

CONCLUSION: Quercetin could significantly ameliorate the pancreatic pathology in rats with HTG related AP, especially acinar necrosis and inflammatory infiltration. The protective effect is dose-dependent.

The role of apheresis in hypertriglyceridemia-induced acute pancreatitis: A systematic review

BACKGROUND

Mostly published as case reports or series, the role of apheresis in hypertriglyceridemia (HTG)-related acute pancreatitis (AP) remains unclear. We performed a systematic review of available literature on this topic with specific focus on disease severity.

METHODS

A search of electronic databases (PubMed, EMBASE, Cochrane) and gray literature yielded 5020 articles of which 74 met criteria for inclusion (301 unique patients). Relevant data were abstracted from full manuscripts and analyzed.

RESULTS

Most patients were young (mean age 37.9 ± 10.4 years) and male (71.5%). About two-thirds (69.7%) received apheresis within 48 h and most required only 1 or 2 sessions (84.4%). Apheresis resulted in an average reduction of serum TG by 85.4% (p < 0.001). There was high variability in reporting the presence of and criteria to define severe AP (reported 221/301, 73.4%; present 85/221, 38.5%) or organ failure (reported 104/301, 34.6%; present 52/104, 50.0%). Improvement was reported in the majority of patients (reported 144/301, 47.8%, present 136/144, 94.4%) mainly by clinical symptoms or laboratory tests. Overall mortality was 7.1% (21/294) which increased to 11.8% (10/85) with severe AP and 19.2% (10/52) with organ failure.

CONCLUSIONS

Apheresis effectively reduces serum TG levels. However, due to uncontrolled data, reporting bias and lack of a comparison group, definitive conclusions on the efficacy of apheresis in reducing AP severity cannot be made. We propose which patients may be best suitable for apheresis, type of studies needed and outcome measures to be studied in order to provide empiric data on the role of apheresis in HTG-related AP.