The effects of contrast agent and intraductal pressure changes on the development of pancreatitis in an ERCP model in rats

How Alcohol Induces Human Acute Alcoholic Pancreatitis-Problem Solved?

It has been a puzzle why only a minority of heavy alcohol drinkers develop acute alcoholic pancreatitis. In this review, the sparse data available from published studies were collected and, based on them, a hypothesis was formed. Long-term high alcohol consumption results in lowered cholecystokinin and cholinergic stimulus of the pancreas, and causes concentration and acidification of pancreatic fluid, predisposing to protein secretion. Early during the withdrawal period when returning to a normal or high-fat nonalcoholic diet, there is a relative hyperstimulation of the pancreas, a well-established mechanism that results in experimental acute pancreatitis. Lower, physiological stimulation is enough to start acute pancreatitis, when the secretions cause temporary obstruction in the duct system; the stimulation against temporary obstruction is also well-known to result in experimental acute pancreatitis. The magnitude of alcohol-induced deficits in acinar cell defense mechanisms then finally determines the onset of pancreatitis.

Usefulness of pancreatic volume quantitative analysis as a predictor of development and severity of post-endoscopic retrograde cholangiopancreatography pancreatitis

BACKGROUND

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is one of the most common and serious adverse events associated with ERCP. Thus, we aimed to investigate the usefulness of pre-ERCP pancreatic volume, which is deeply involved in exocrine pancreatic function, as a predictor of PEP development and severity.

METHODS

In total, 1107 patients who underwent their first ERCP were recruited from January 2012 to December 2022 for this retrospective study. Pancreatic volume was measured by cross-sectional analysis using pre-ERCP computed tomography images. The potential risk factors for PEP were analyzed using multivariate logistic regression.

RESULTS

Of the 745 patients included in the study, 34 (4.6 %) developed PEP: severe, moderate, or mild PEP in 1, 7, and 26 cases, respectively. Multivariate analysis revealed that only a large pancreatic volume (>70 cm3) was an independent risk factor for the development of PEP (odds ratio, 7.98; 95 % confidence interval, 11.80-67.50; P < 0.001). Additionally, the incidence of PEP was significantly higher in patients with a pancreatic volume >70 cm3 than in those with a pancreatic volume ≤70 cm3 (18.5 % [31/168] vs. 0.5 % [3/577]; P < 0.001). Also, the association between the pre-ERCP pancreatic volume and PEP severity was positively correlated (r = 0.625, P < 0.005), with a larger pancreatic volume corresponding to increased PEP severity.

CONCLUSIONS

A large pancreatic volume before ERCP may be a novel risk factor for PEP incidence and severity. This finding suggests that quantitative analysis of the pre-ERCP pancreatic volume could be a useful predictor of PEP.

Pancreatic duct pressure: A review of technical aspects and clinical significance

Pancreatic duct pressure (PDP) dynamics comprise an intricately modulated system that helps maintain homeostasis of pancreatic function. It is affected by various factors, including the rate of pancreatic fluid secretion, patency of the ductal system, sphincter of Oddi function, and pancreatic fluid characteristics. Disease states such as acute and chronic pancreatitis can alter the normal PDP dynamics. Ductal hypertension or increased PDP is suspected to be involved in the pathogenesis of pancreatic pain, endocrine and exocrine pancreatic insufficiency, and recurrent pancreatitis. This review provides a comprehensive appraisal of the available literature on PDP, including the methods used in the measurement and clinical implications of elevated PDP.

Radiocontrast agent and intraductal pressure promote the progression of post-ERCP pancreatitis by regulating inflammatory response, cellular apoptosis, and tight junction integrity

OBJECTIVE

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is the most common complication following ERCP and the mechanism is not fully understood. This study evaluated the changes in the inflammatory response, cellular apoptosis, and tight junction integrity in a rat model of pancreatitis to explore the underlying mechanism.

METHODS

PEP was induced in rats by retrograde biliopancreatic ductal infusion of contrast agents or saline. Pancreatic tissues were harvested and evaluated by histopathologic, immunohistochemical, immunofluorescence, and Western blot analyses. In addition, amylase and proinflammatory cytokines in plasma were quantified by ELISA assay.

RESULTS

PEP rats developed more severe acute pancreatitis than the sham group after injection of the contrast agent or isotonic saline. PEP rats exhibited increased tissue damage, plasma amylase, proinflammatory cytokines, necrosis, inflammatory infiltrates, apoptosis, and tight junction disruption. At the molecular level, contrast agent and isotonic saline-injected PEP rats demonstrated elevated NF-κB p65 and STAT3 pathways activation, altered expression and activation of apoptosis-related proteins, and suppressed expression of tight junction molecules. However, the contrast agent concentration had no effect on these changes.

CONCLUSIONS

In models of acute pancreatitis induced using contrast agent and hydrostatic pressure, the contrast agent and high hydrostatic pressure easily induced the inflammatory response, apoptosis, and tight junction disruption. It is noteworthy that no significant difference in damaged pancreatic acinar cells was observed with different concentrations of the contrast agent.

Experimental Acute Pancreatitis Models: History, Current Status, and Role in Translational Research

Acute pancreatitis is a potentially severe inflammatory disease that may be associated with a substantial morbidity and mortality. Currently there is no specific treatment for the disease, which indicates an ongoing demand for research into its pathogenesis and development of new therapeutic strategies. Due to the unpredictable course of acute pancreatitis and relatively concealed anatomical site in the retro-peritoneum, research on the human pancreas remains challenging. As a result, for over the last 100 years studies on the pathogenesis of this disease have heavily relied on animal models. This review aims to summarize different animal models of acute pancreatitis from the past to present and discuss their main characteristics and applications. It identifies key studies that have enhanced our current understanding of the pathogenesis of acute pancreatitis and highlights the instrumental role of animal models in translational research for developing novel therapies.

SpHincterotomy for Acute Recurrent Pancreatitis Randomized Trial: Rationale, Methodology, and Potential Implications

OBJECTIVES

In patients with acute recurrent pancreatitis (ARP), pancreas divisum, and no other etiologic factors, endoscopic retrograde cholangiopancreatography (ERCP) with minor papilla endoscopic sphincterotomy (miES) is often performed to enlarge the minor papillary orifice, based on limited data. The aims of this study are to describe the rationale and methodology of a sham-controlled clinical trial designed to test the hypothesis that miES reduces the risk of acute pancreatitis.

METHODS

The SpHincterotomy for Acute Recurrent Pancreatitis (SHARP) trial is a multicenter, international, sham-controlled, randomized trial comparing endoscopic ultrasound + ERCP with miES versus endoscopic ultrasound + sham for the management of ARP. A total of 234 consented patients having 2 or more discrete episodes of acute pancreatitis, pancreas divisum confirmed by magnetic resonance cholangiopancreatography, and no other clear etiology for acute pancreatitis will be randomized. Both cohorts will be followed for a minimum of 6 months and a maximum of 48 months.

RESULTS

The trial is powered to detect a 33% risk reduction of acute pancreatitis frequency.

CONCLUSIONS

The SHARP trial will determine whether ERCP with miES benefits patients with idiopathic ARP and pancreas divisum. Trial planning has informed the importance of blinded outcome assessors and long-term follow-up.

Transient High Pressure in Pancreatic Ducts Promotes Inflammation and Alters Tight Junctions via Calcineurin Signaling in Mice

BACKGROUND & AIMS

Pancreatitis after endoscopic retrograde cholangiopancreatography (PEP) is thought to be provoked by pancreatic ductal hypertension, via unknown mechanisms. We investigated the effects of hydrostatic pressures on the development of pancreatitis in mice.

METHODS

We performed studies with Swiss Webster mice, B6129 mice (controls), and B6129 mice with disruption of the protein phosphatase 3, catalytic subunit, βisoform gene (Cnab-/- mice). Acute pancreatitis was induced in mice by retrograde biliopancreatic ductal or intraductal infusion of saline with a constant hydrostatic pressure while the proximal common bile duct was clamped -these mice were used as a model of PEP. Some mice were given pancreatic infusions of adeno-associated virus 6-nuclear factor of activated T-cells-luciferase to monitor calcineurin activity or the calcineurin inhibitor FK506. Blood samples and pancreas were collected at 6 and 24 hours and analyzed by enzyme-linked immunosorbent assay, histology, immunohistochemistry, or fluorescence microscopy. Ca2+ signaling and mitochondrial permeability were measured in pancreatic acinar cells isolated 15 minutes after PEP induction. Ca2+-activated phosphatase calcineurin within the pancreas was tracked in vivo over 24 hours.

RESULTS

Intraductal pressures of up to 130 mm Hg were observed in the previously reported model of PEP; we found that application of hydrostatic pressures of 100 and 150 mm Hg for 10 minutes consistently induced pancreatitis. Pancreatic tissues had markers of inflammation (increased levels of interleukin [IL] 6, IL1B, and tumor necrosis factor), activation of signal transducer and activator of transcription 3, increased serum amylase and IL6, and loss of tight junction integrity. Transiently high pressures dysregulated Ca2+ processing (reduced Ca2+ oscillations and an increased peak plateau Ca2+ signal) and reduced the mitochondrial membrane potential. We observed activation of pancreatic calcineurin in the pancreas in mice. Cnab-/- mice, which lack the catalytic subunit of calcineurin, and mice given FK506 did not develop pressure-induced pancreatic inflammation, edema, or loss of tight junction integrity.

CONCLUSIONS

Transient high ductal pressure produces pancreatic inflammation and loss of tight junction integrity in a mouse model of PEP. These processes require calcineurin signaling. Calcineurin inhibitors might be used to prevent acute pancreatitis that results from obstruction.

Pancreatic Stenting Reduces Post-ERCP Pancreatitis and Biliary Sepsis in High-Risk Patients: A Randomized, Controlled Study

Background. Endoscopic retrograde cholangiopancreatography (ERCP) is an established treatment modality for bile duct disorders, but patients have a risk of post-ERCP pancreatitis (PEP) and biliary sepsis. Aim. To evaluate the effectiveness and safety of pancreatic stent for prophylaxis of PEP and biliary sepsis in high-risk patients with complicating common bile duct (CBD) disorders. Methods. Two hundred and six patients with complicating confirmed or suspected CBD disorders were randomly assigned to receive ERCP with pancreatic stenting (experimental group) or without stenting (control group). Primary outcome measure was frequency of PEP, and secondary outcome measures included operative time, blood loss, postoperative recovery times, and other ERCP-associated morbidities. Results. Baseline age, sex, CBD etiology, concomitant medical/surgical conditions, cannulation difficulty, and ERCP success were comparable between the two groups (all P > 0.05). Compared to the control group, the experimental group had a significantly lower frequency of PEP (7.7% versus 17.7%, P < 0.05) and positive bile microbial culture (40.4% versus 62.7%, P < 0.05). However, the two groups were similar in operative time, blood loss, postoperative recovery times, and other ERCP-associated morbidities (all P > 0.05). Conclusions. Pancreatic stenting can reduce the occurrence of PEP and biliary sepsis in high-risk patients with complicating CBD disorders but does not increase other ERCP-associated morbidities. This trial is registered with the Chinese Clinical Trial Registry (registration identifier ChiCTR-OCH-14005134).

Exposure to Radiocontrast Agents Induces Pancreatic Inflammation by Activation of Nuclear Factor-κB, Calcium Signaling, and Calcineurin

BACKGROUND & AIMS

Radiocontrast agents are required for radiographic procedures, but these agents can injure tissues by unknown mechanisms. We investigated whether exposure of pancreatic tissues to radiocontrast agents during endoscopic retrograde cholangiopancreatography (ERCP) causes pancreatic inflammation, and studied the effects of these agents on human cell lines and in mice.

METHODS

We exposed mouse and human acinar cells to the radiocontrast agent iohexol (Omnipaque; GE Healthcare, Princeton, NJ) and measured intracellular release of Ca(2+), calcineurin activation (using a luciferase reporter), activation of nuclear factor-κB (NF-κB, using a luciferase reporter), and cell necrosis (via propidium iodide uptake). We infused the radiocontrast agent into the pancreatic ducts of wild-type mice (C57BL/6) to create a mouse model of post-ERCP pancreatitis; some mice were given intraperitoneal injections of the calcineurin inhibitor FK506 before and after infusion of the radiocontrast agent. CnAβ(-/-) mice also were used. This experiment also was performed in mice given infusions of adeno-associated virus 6-NF-κB-luciferase, to assess activation of this transcription factor in vivo.

RESULTS

Incubation of mouse and human acinar cells, but not HEK293 or COS7 cells, with iohexol led to a peak and then plateau in Ca(2+) signaling, along with activation of the transcription factors NF-κB and nuclear factor of activated T cells. Suppressing Ca(2+) signaling or calcineurin with BAPTA, cyclosporine A, or FK506 prevented activation of NF-κB and acinar cell injury. Calcineurin Aβ-deficient mice were protected against induction of pancreatic inflammation by iohexol. The calcineurin inhibitor FK506 prevented contrast-induced activation of NF-κB in pancreata of mice, this was observed by live imaging of mice given infusions of adeno-associated virus 6-NF-κB-luciferase.

CONCLUSIONS

Radiocontrast agents cause pancreatic inflammation in mice, via activation of NF-κB, Ca(2+) signaling, and calcineurin. Calcineurin inhibitors might be developed to prevent post-ERCP pancreatitis in patients.

Balloon dilation itself may not be a major determinant of post-endoscopic retrograde cholangiopancreatography pancreatitis

Endoscopic retrograde cholangiopancreatography (ERCP) is the essential first modality for common bile duct (CBD) stone therapy. The conventional endoscopic treatment for CBD stones is stone removal after endoscopic sphincterotomy (EST). Stone removal after papillary stretching using balloon dilation instead of the conventional method has been widely adopted. There are many reports regarding endoscopic papillary balloon dilation (EPBD) utilizing a small balloon (< 10 mm) instead of EST for the removal of small CBD stones. In contrast, two cases of mortality due to post-ERCP pancreatitis (PEP) were reported after an EPBD clinical trial in the Western world, and the psychological barrier caused by these incidences hinders the use of this technique in Western countries. Endoscopic papillar large balloon dilation (EPLBD), which is used to treat large CBD stones, was not widely adopted when first introduced due to concerns about perforation and severe pancreatitis from the use of a large balloon (12-20 mm). However, as experience with this procedure accumulates, the occurrence of PEP with EPLBD is confirmed to be much lower than with EPBD. This report reviews whether EPBD and EPLBD, two procedures that use balloon dilation but differ in terms of indications and concept, contribute to the occurrence of PEP.

Effects of contrast media on the hepato-pancreato-biliary system

AIM: To determine the effects of high osmolarity contrast media (HOCM) and iso-osmolar contrast media (CM) application, with or without pressure, on hepato-pancreato-biliary (HPB) system.

METHODS: Sixty rats were divided into six equal groups as follows: Group 1: (0.9% NaCl, control), Group 2: (diatrizoate meglumine Na, ionic HOCM, Urographin^®), Group 3: (iodixanol, iso-osmolar non-ionic CM, Visipaque^®); each of which was applied without pressure, whereas the animals of the remaining three groups (1p, 2p, 3p) were subjected to the same CM with pressure. We performed a duodenal puncture and introduced a catheter into the ampulla. After the catheterization, 0.2 mL CM or 0.9% NaCl was injected with or without pressure. Blood samples were taken for biochemical evaluations. The histopathological examinations of liver, common bile duct, and pancreas were performed.

RESULTS: There were no significant differences between the six groups for blood amylase, alanine aminotransferases, aspartate aminotransferases, bilirubin levels (P > 0.05). Alkaline phosphatase and γ glutamyl transaminase levels were higher (P < 0.05) in the Urographin^® groups (2, 2p) than the Visipaque^® groups (3, 3p), or control groups (1, 1p). Hepatocyte necrosis, portal area inflammation, and Kupffer’s cell hyperplasia were higher (P < 0.05) in the study groups than the control group. However, there were no significant differences (P > 0.05) between HOCM (2, 2p) and iso-osmolar CM (3, 3p) groups. Bile duct proliferation and regeneration in the Urographin^® groups (2, 2p) were significantly higher (P < 0.05) than the Visipaque^® groups (3, 3p) or the control groups (1, 1p). Although CM caused minor damage to the pancreas, there were no statistically significant differences (P > 0.05) between the groups. Application of the CM with pressure did not cause additional damage to the HPB system.

CONCLUSION: Iso-osmolar, non-ionic CM could be more reliable than the ionic HOCM, whereas the application of pressure during the CM application had no effect on the HPB system.