Interleukin-1 receptor antagonist decreases severity of experimental acute pancreatitis

TNF but not IL-1 decreases pancreatic acinar cell survival without affecting exocrine function: a study in the perfused human pancreas

Substantial quantities of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) are produced within the pancreatic parenchyma during acute pancreatitis. Recent evidence suggests that IL-1 beta and TNF-alpha propagate acute pancreatitis and intensify the resulting pancreatic acinar cell death. This study examines the direct effect of IL-1 beta and TNF-alpha on pancreatic acinar cells. Human pancreata (n = 6), harvested during organ procurement, were perfused ex vivo through the splenic artery using a sterile, oxygenated colloid solution. Each pancreas was perfused with either recombinant human IL-1 beta or TNF-alpha for 2 h and subsequently with the cholecystokinin analogue caerulein (positive control). Venous effluent was collected continuously and amylase and lipase were determined at 15-min intervals. Pancreatic histology was graded at baseline and following cytokine and caerulein perfusion. To examine the long-term effects of these cytokines on acinar cell viability, additional in vitro studies utilized the AR42J acinar cell line which was exposed to either IL-1 beta or TNF-alpha with survival determined daily by MTT assay. Perfusion of the human pancreas with either IL-1 beta or TNF-alpha did not alter amylase, lipase, or histology. Caerulein did induce pancreatitis as measured by increased amylase, lipase, and pancreatic histology. Survival of pancreatic acinar cells decreased when they were incubated with TNF-alpha but not IL-1 beta. Although present in large amounts within the pancreas during acute pancreatitis, IL-1 beta and TNF-alpha have no direct effect on acinar cell viability or exocrine function acutely nor do they induce pancreatitis. When present for more than 24 h, however, TNF-alpha but not IL-1 beta has a dramatic effect on acinar cell survival.

The relative safety of MRI contrast agent in acute necrotizing pancreatitis

OBJECTIVE

To validate the safety of gadolinium-diethylenetriamine pentaacetic acid (GD-DTPA) by measuring its effect on pancreatic capillary perfusion and acinar injury in acute pancreatitis.

BACKGROUND

Contrast-enhanced computed tomography (CECT) is proposed as a gold standard for early evaluation of acute necrotizing pancreatitis. However, iodinated contrast media used for CECT have been shown in these circumstances to reduce pancreatic capillary flow and increase necrosis and mortality. Recent reports suggest that post-GD MRI provides images comparable to CECT in the assessment of severe acute pancreatitis.

METHODS

Necrotizing pancreatitis was induced in 14 Wistar rats by intraductal glycodeoxycholic acid (10 mM/L) and intravenous caerulein (5 microg/kg/h) over 6 hours. Intravital microscopic quantitation of pancreatic capillary blood flow was performed using fluorescein isothiocyanate-labeled erythrocytes after induction of pancreatitis and 30 and 60 minutes after an intravenous bolus of either Ringer's solution or GD-DTPA (0.2 mL/kg).

RESULTS

The two study groups were comparable with regard to mean arterial pressure, heart rate, arterial blood gases, hematocrit, amylase, lipase, and trypsinogen activation peptide production throughout the experiment. GD-DTPA did not reduce capillary flow (1.93 +/- 0.05 nL/capillary/min) compared to animals infused with Ringer's solution (1.90 +/- 0.06 nL/capillary/min).

CONCLUSIONS

Intravenous injection of GD-DTPA does not further impair pancreatic microcirculation or increase acinar injury in acute necrotizing pancreatitis. Because of this advantage over CT contrast medium, further development of MRI as a staging tool in acute pancreatitis seems desirable.

Pretreatment with methylprednisolone to prevent ERCP-induced pancreatitis: a randomized, multicenter, placebo-controlled clinical trial

OBJECTIVE

Pancreatitis remains the major complication of endoscopic retrograde cholangiopancreatography (ERCP). Uncontrolled data suggest a lower incidence of pancreatitis in patients with a history of iodine sensitivity when given pretreatment with corticosteroids. We conducted a clinical trial to assess the efficacy of a commonly prescribed corticosteroid, methylprednisolone, to prevent ERCP-induced pancreatitis.

METHODS

Patients were entered into a randomized, multicenter, double-blind, placebo-controlled study of intravenous methylprednisolone (125 mg) versus a saline placebo immediately before the ERCP. All patients were evaluated for early and late complications.

RESULTS

Two hundred eighty-six patients were randomized. Thirty-one randomized patients were excluded for technical reasons at the time of ERCP. Overall, the incidence of pancreatitis was 16 of 129 (12.4%, 95% CI: 6.7-18.1%) in the methylprednisolone group and 11 of 126 (8.7%, 95% CI: 4.4-15.1%) in the placebo group, which was not significantly different (p = 0.34). Although there was a higher rate of sphincterotomy performed in the methylprednisolone group compared to the control group (31.8% vs 16.8%, p = 0.005), the incidence of pancreatitis was not different when patients undergoing sphincterotomy were analyzed separately (13.6% in the methylprednisolone group and 9.6% in the placebo group,p = 0.50). There was no significant difference between the two groups for those with ERCP-induced pancreatitis in hospital length of stay (p = 0.22), days of parenteral analgesia (p = 0.09), or days of parenteral nutrition (p = 0.15).

CONCLUSION

Intravenous methylprednisolone is not beneficial in preventing ERCP-induced pancreatitis.

The role of cytokines in the pathogenesis of acute pancreatitis

BACKGROUND

The systemic manifestations of acute pancreatitis are responsible for the majority of pancreatitis-associated morbidity and mortality and are now believed to be due to the actions of specific inflammatory cytokines. This report summarizes what is known about the role of cytokines in the pathogenesis of acute pancreatitis.

METHODS

Comprehensive literature review of experimental pancreatitis as well as all reports of cytokine involvement during clinical pancreatitis.

RESULTS

Several cytokines and other noncytokine inflammatory mediators are produced rapidly during pancreatitis. These mediators arise in many tissues in a predictable fashion independent of the animal model used or the underlying etiology in human disease. Preventing the activities of these mediators has a profound beneficial effect in experimental animals.

CONCLUSIONS

A few recently described inflammatory mediators are believed to be primarily responsible for the systemic manifestations of acute pancreatitis and its associated distant organ dysfunction. The predictable nature in which they are produced may allow for novel approaches to treating this disease. Am J Surg.

Biosynthesis and secretion of MHC class III gene products (complement C4 and factor B) in the exocrine pancreas

We recently found that complement C3 is locally synthesized and secreted into the exocrine pancreas. In the present study, we attempted to demonstrate the secretion of complement C4 and factor B in the exocrine pancreas. In five samples of pancreatic fluid, both C4 and factor B proteins were detected by enzyme-linked immunosorbent assay (ELISA). Immunoblot analysis revealed the C4 and factor B molecules in pancreatic fluid to be identical with these molecules in serum. Reverse transcriptase (RT)-polymerase chain reaction (PCR) analysis in pancreatic carcinoma cell lines suggested ductal epithelial cells to be the local production sites of these proteins in the pancreas. The secretion of C4 and factor B in ductal cell lines (PANC-1 and MIA PaCa-2) was independently regulated by interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma; C4 secretion was induced by IFN-gamma, whereas factor B secretion was induced by IL-1 beta, TNF-alpha, or IFN-gamma. These observations indicate that: (a) complement C4 and factor B are secreted into the exocrine pancreas, (b) ductal epithelial cells appear to be the site of C4 and factor B biosynthesis, and (c) local secretion of C4 and factor B in the pancreas is differentially regulated by IL-1 beta, TNF-alpha, and IFN-gamma.

Interleukin-10 reduces circulating levels of serum cytokines in experimental pancreatitis

Over the past few years, evidence has accumulated that implicates proinflammatory cytokines as the mediators responsible for the escalation of acute pancreatitis into a multisystem disease. It has been shown that the degree of serum cytokine elevation, particularly the macrophage-derived cytokines interleukin-1, interleukin-6, and tumor necrosis factor-alpha, correlates with the severity and outcome of acute pancreatitis. Interleukin-10 is an anti-inflammatory cytokine that inhibits cytokine production from the macrophage. The aim of this study was to determine whether interleukin-10 would decrease both the severity of acute pancreatitis and the level of circulating proinflammatory cytokines. Ninety female mice were divided into three equal groups. Group 1 (controls) received intraperitoneal saline solution. Groups 2 and 3 received intraperitoneal cerulein (50 mg/kg/hr) for 7 hours. In addition, group 3 was given 1500 units of intraperitoneal interleukin-10, beginning 1 hour after the induction of acute pancreatitis and every 3 hours thereafter. Animals were killed at 3-hour intervals. Blood samples were obtained for serum amylase and cytokine determinations (interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha). Pancreata were dissected free and fixed in formalin for blinded histologic scoring. Interleukin-10 reduced the serum levels of interleukin-1beta, interleukin-6, tumor necrosis factor-alpha, and amylase in comparison to untreated animals with pancreatitis (P < 0.05). Pancreatic edema, necrosis, and inflammatory cell infiltrate were also reduced in those animals given interleukin-10 (P <0.05). Histologic score, serum cytokines, and amylase levels are elevated during acute pancreatitis. Interleukin-10 given therapeutically, that is, after the onset of acute pancreatitis, lessened the severity of disease, probably through inhibition of the macrophage. This was associated with a decrease in circulating cytokine levels.

Severity and mortality of experimental pancreatitis are dependent on interleukin-1 converting enzyme (ICE)

Interleukin-1 beta (IL-1 beta) is produced in large amounts during acute pancreatitis and is believed to play a role in disease progression. Because secretion of IL-1 beta is dependent on intracellular processing of pro-IL-1 beta by IL-1 converting enzyme (ICE), we aimed to determine the efficacy of a novel ICE inactivator (VE-13045) in inhibiting secretion of active IL-1 beta in vivo and if the loss of ICE activity would affect the severity and mortality of experimental pancreatitis. Severe hemorrhagic pancreatitis was induced in adult rats by infusion of bile acid into the pancreatic duct. Animals were randomized to receive VE-13045 or vehicle before induction of pancreatitis. To confirm our findings and to ensure that the results were not model dependent, a second series of experiments was conducted using mice possessing a homozygous knockout of the ICE gene in which lethal pancreatitis was induced by feeding a choline-deficient, ethionine-supplemented diet. The severity of pancreatitis was assessed for both experiments by standard surrogate markers, blind histologic grading, and serum IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) levels. Pancreatic IL-1 beta mRNA induction was assessed by differential RT-PCR. Acute pancreatitis was associated with a 120-fold increase in IL-1 beta mRNA, which was not affected by ICE inhibition or gene deletion. Cytokine processing and secretion were affected, as evidenced by decreased serum levels of IL-1 beta and TNF-alpha (p < 0.001) in all animals with an inactive ICE enzyme. This lack of cytokine production increased survival from 32% to 78% following bile salt pancreatitis (p < 0.01) and from 24% to 80% following diet-induced pancreatitis (p < 0.005). Both ICE-defective groups demonstrated decreased pancreatic necrosis, edema, inflammation, wet weight (all p < 0.05), and amylase and lipase (p < 0.01). In vivo blockade or genetic deletion of ICE inhibits pancreatitis-induced secretion of proinflammatory cytokines without altering IL-1 mRNA production and is associated with decreased pancreatitis severity and dramatic survival benefits.

Timing of tumor necrosis factor antagonism is critical in determining outcome in murine lethal acute pancreatitis

BACKGROUND

Tumor necrosis factor (TNF) is produced in large amounts within the pancreas, lungs, and liver during severe acute pancreatitis and is believed to mediate many of the detrimental consequences typical of this disease. Investigations into the benefit of TNF antagonism have suggested that TNF may also mediate processes that are protective to the host.

METHODS

With the hypothesis that timing plays a role in these dissenting views, TNF was antagonized either prophylactically or therapeutically with a recombinant form of the soluble type I TNF receptor (TNFbp) during a lethal model of necrotizing pancreatitis induced by feeding a choline-deficient diet. Mortality was determined for 10 days in 390 female mice divided into three groups: control, TNFbp early (time, 0 to 5 days), and TNFbp late (time, 1.5 to 5 days). Pancreatitis severity and cytokine production were assessed daily.

RESULTS

Animals in the control group had a 75% mortality rate that was significantly decreased by prophylactic TNF blockade (64%, p < 0.05). Delaying TNF antagonism until serum cytokines were elevated and pancreatitis was manifest decreased mortality to 42% (p < 0.001 versus control, p < 0.01 versus early). Early and late TNF blockade decreased pancreatic edema and serum amylase, lipase, interleukin-1, and interleukin-6 (all p < 0.05) but not TNF. Late antagonism typically resulted in the greatest attenuation of all these parameters.

CONCLUSIONS

Blockade of TNF by the administration of a soluble TNF receptor attenuates the severity of pancreatitis, decreases the production of associated inflammatory cytokines, and significantly improves survival. Delaying antagonism until pancreatitis is manifest and circulating cytokines are elevated but not yet maximal appears to be more protective than simple prophylactic TNF antagonism.

Interleukin-10 prevents death in lethal necrotizing pancreatitis in mice

BACKGROUND

Cytokines derived from macrophages may play an integral role in the evolution of acute pancreatitis. Interleukin-10 (IL-10), a potent antiinflammatory cytokine, prevents the activation of macrophages and their release of inflammatory cytokines. The aim of this study was to determine whether treatment with IL-10 decreased the severity of experimental acute pancreatitis.

METHODS

Thirty female Swiss Webster mice were divided into three groups. Acute pancreatitis was induced by using a choline-deficient, 0.5% ethionine supplemented (CDE) diet. Group A (controls) received CDE diet alone. Group B was pretreated with 10,000 units of intraperitoneal IL-10 at the onset of feeding and every 8 hours thereafter. Group C received IL-10 33 hours after beginning the CDE diet and every 8 hours thereafter. One half of the animals in each group was killed at 54 hours; the remaining living animals were killed at 80 hours. Serum amylase levels (units per liter) were determined at 54 and 80 hours. Pancreata were harvested and fixed in formalin. Histologic characteristics were graded on a scale from 0 to 4 (normal to most abnormal) in a blinded fashion by two investigators.

RESULTS

Serum amylase level and histologic score (edema, inflammation, hemorrhage, and necrosis) were significantly reduced when IL-10 was administered either prophylactically or therapeutically (p < 0.01). At 54 hours all animals were alive. Mortality was reduced at 80 hours in both groups treated with IL-10 compared with those fed the CDE diet alone (p < 0.001).

CONCLUSIONS

These results suggested that macrophages play an integral role in determining the severity of acute pancreatitis in this animal model. The finding that IL-10 decreased inflammation and prevented death, even when given after acute pancreatitis was established, suggests that it may have potential for clinical use.

Tissue-specific regulation of glutamine synthetase gene expression in acute pancreatitis is confirmed by using interleukin-1 receptor knockout mice

BACKGROUND

Acute pancreatitis causes a pronounced depletion of plasma and muscle glutamine pools. In several other catabolic disease states expression of the enzyme glutamine synthetase (GS) is induced in lung and muscle to support glutamine secretion by these organs. The hormonal mediators of GS induction have not been conclusively identified. We used mice deficient for the expression of the type 1 interleukin-1 receptor (IL-1R1 knockout mice) to investigate the expression of GS during acute edematous pancreatitis.

METHODS

Acute edematous pancreatitis was induced in adult male wild-type and IL-1R1 knockout mice by means of the intraperitoneal administration of cerulein, and their conditions were monitored. Five organs, including lung, liver, gastrocnemius muscle, spleen, and pancreas, were assayed for relative GS messenger RNA (mRNA) content by Northern blotting.

RESULTS

The ultimate severity of pancreatitis was reduced by IL-1R1 deficiency. GS mRNA levels increased during progression of pancreatitis in lung, spleen, and muscle tissue from each group. No consistent increase in GS mRNA level was observed in liver. IL-1R1 deficiency did not affect GS mRNA expression in lung tissue but consistently retarded GS induction in the spleens of knockout animals. IL-1R deficiency altered the kinetics of GS induction in muscle.

CONCLUSIONS

Cerulein-induced experimental pancreatitis causes an induction in GS mRNA levels in a tissue-specific fashion. IL-1R1 deficiency reduced the ultimate severity of the condition and altered the induction of GS mRNA in the spleen and muscle.

Interleukins in acute pancreatitis

Cytokines and their endogenous antagonists are released from inflammatory cells during acute pancreatitis, in particular its severe form. They can be found early in the course of the disease as is shown in animal models and in endoscopic retrograde cholangio-pancreatography (ERCP) induced human pancreatitis. Cytokine measurements can predict the course of the disease. This can, however, be achieved using more simple parameters, such as clinical judgement and leucocyte elastase. Anticytokine strategies in the treatment of severe acute pancreatitis should be further evaluated since some positive effects have been found in experimental settings. Interleukin 10 or soluble TNF alpha-receptors may be good candidates. Plasmapheresis seems to change cytokine-anticytokines patterns and this also needs to be explored in controlled trials.

Decreased mortality of severe acute pancreatitis after proximal cytokine blockade

OBJECTIVE

This study determined the ability of interleukin-1 receptor antagonist (IL-1ra) to decrease the mortality of experimental acute pancreatitis. The response of the inflammatory cytokine cascade and its subsequent effects on pancreatic morphology were measured to determine the role of these peptides in mediating pancreatic injury.

SUMMARY BACKGROUND DATA

Previous studies have shown that proinflammatory cytokines are produced in large amounts during acute pancreatitis and that blockade at the level of the IL-1 receptor significantly decreases intrinsic pancreatic damage. The subsequent effect on survival is not known.

METHODS

A lethal form of acute hemorrhagic necrotizing pancreatitis was induced in young female mice by feeding a choline-deficient, ethionine supplemented (CDE) diet for 72 hours. For determination of mortality, the animals were divided into 3 groups of 45 animals each: control subjects received 100/microL normal saline intraperitoneally every 6 hours for 5 days; IL-1ra early mice received recombinant interleukin-1 receptor antagonist 15 mg/kg intraperitoneally every 6 hours for 5 days beginning at time 0; IL-1ra late mice received IL-1ra 15 mg/kg intraperitoneally every 6 hours for 3.5 days beginning 1.5 days after introduction of the CDE diet. A parallel experiment was conducted simultaneously with a minimum of 29 animals per group, which were sacrificed daily for comparisons of serum amylase, lipase, IL-1, IL-6, tumor necrosis factor-alpha, IL-1ra, pancreatic wet weight, and blind histopathologic grading.

RESULTS

The 10-day mortality in the untreated control group was 73%. Early and late IL-1ra administration resulted in decreases of mortality to 44% and 51%, respectively (both p < 0.001). Interleukin-1 antagonism also was associated with a significant attenuation in the rise in pancreatic wet weight and serum amylase and lipase in both early and late IL-1ra groups (all p < 0.05). All control animals developed a rapid elevation of the inflammatory cytokines, with maximal levels reached on day 3. The IL-1ra-treated animals, however, demonstrated a blunted rise of these mediators (all p < 0.05). Blind histologic grading revealed an overall decrease in the severity of pancreatitis in those animals receiving the antagonist.

CONCLUSIONS

Early or late blockade of the cytokine cascade at the level of the IL-1 receptor significantly decreases the mortality of severe acute pancreatitis. The mechanism by which this is accomplished appears to include attenuation of systemic inflammatory cytokines and decreased pancreatic destruction.