Active interleukin-1 receptor required for maximal progression of acute pancreatitis

IL27 and IL1RN are causally associated with acute pancreatitis: a Mendelian randomization study

BACKGROUND

The interleukin (IL) plays a role in the development of acute pancreatitis (AP). However, the specific IL in AP has not been fully revealed. Therefore, the association between prospective IL and AP was studied via Mendelian randomization (MR).

METHODS

The HUGO Gene nomenclature committee (HGNC) database provided 47 interleukin related genes (ILRGs). ILRGs and differentially expressed genes (DEGs) from GSE194331 were overlapped to create differently expressed ILRGs (DE-ILRGs). The integrative epidemiology unit (IEU) open genome-wide association study (GWAS) database provided exposure and outcome datasets. Univariate MR (UVMR) analysis using MR-Egger, IVW, simple mode, and weighted mode was done. UVMR results were verified using sensitivity analysis. Drug prediction, MVMR analysis, and PPI network development were also performed.

RESULTS

Six DE-ILRGs were obtained. IL27 and IL1RN were substantially causally linked with AP by UVMR analysis (OR = 0.926, P < 0.001 and OR = 1.031, P = 0.023). Our sensitivity analysis showed the dependability of our results. Direct effect of IL27 was suggested by MVMR analysis. In the cytokine receptor binding pathway, IL27 and IL1RN interacted with IL36G and IL1R2. TAE-684, ARQ-680, and 12 other IL1RN and 14 IL27 medications were predicted.

CONCLUSIONS

IL1RN was identified as a risk factor for acute pancreatitis (AP), but IL27 was found to be a protective factor for AP.

Interleukins: pathophysiological role in acute pancreatitis

Acute pancreatitis (AP) is a common inflammatory state characterized by a clinical course that can lead to serious local and extrapancreatic organ malfunction and failure. Interleukins (ILs) are biologically active glycoproteins primarily produced by macrophages and lymphocytes. According to the literature, there are many ILs. However, this article represents a summary of the role of ILs in AP, such as IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15, IL-16, IL-17, IL-18, IL-19, and IL-20. The ways to modulate IL activity to reduce inflammation and improve outcomes in individuals with this condition are under investigation. Drugs that target specific ILs might be developed to mitigate the effects of AP.

Early immune response in post endoscopic retrograde cholangiopancreatography pancreatitis as a model for acute pancreatitis

This opinion review summarizes comparison of clinical presentation and immunology of post-endoscopic pancreatitis and acute pancreatitis (AP) of other etiology. The rationale for this topic was found in studies that mention differences in clinical presentation between these entities, stating that severe form of AP after endoscopic retrograde cholangiopancreatography was more severe than AP of other etiology. Found difference in clinical presentation may have a background in different immunology that needs to be further investigated.

Fraxinellone inhibits inflammatory cell infiltration during acute pancreatitis by suppressing inflammasome activation

Inflammasomes promote the production of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-18, which are the representative mediators of inflammation. Abnormal activation of inflammasomes leads to the development of inflammatory diseases such as acute pancreatitis (AP). In this study, we demonstrate the inhibitory effects of a new natural compound fraxinellone on inflammasome formation and examine the role of inflammasomes in a mouse model of AP. AP was induced with hourly intraperitoneal injections of supramaximal concentrations of the stable cholecystokinin analogue cerulein (50 μg/kg) for 6 h. Mice were sacrificed 6 h after the final cerulein injection. Blood and pancreas samples were obtained for further experiments. Intraperitoneal injection of fraxinellone significantly inhibited the pancreatic activation of multiple inflammasome molecules such as NACHT, LRR and PYD domains-containing protein 3 (NLRP3), PY-CARD, caspase-1, IL-18, and IL-1β during AP. In addition, fraxinellone treatment inhibited pancreatic injury, elevation in serum amylase and lipase activities, and infiltration of inflammatory cells such as neutrophils and macrophages but had no effect on pancreatic edema. To investigate whether inflammasome activation leads to the infiltration of inflammatory cells, we used parthenolide, a well-known natural inhibitor, and IL-1 receptor antagonist mice. The inhibition of inflammasome activation by pharmacological/or genetic modification restricted the infiltration of inflammatory cells, but not edema, consistent with the results observed with fraxinellone. Taken together, our study highlights fraxinellone as a natural inhibitor of inflammasomes and that inflammasome inhibition may lead to the suppression of inflammatory cells during AP.

Endoscopic retrograde cholangiopancreatography-induced and non-endoscopic retrograde cholangiopancreatography-induced acute pancreatitis: Two distinct clinical and immunological entities?

Acute pancreatitis (AP) is common gastrointestinal disease of varied aetiology. The most common cause of AP is gallstones, followed by alcohol abuse as an independent risk factor. With the increased need for invasive techniques to treat pancreatic and bile duct pathologies such as endoscopic retrograde cholangiopancreatography (ERCP), AP has emerged as the most frequent complication. While severe AP following ERCP is rare (0.5%), if it does develop it has a greater severity index compared to non-ERCP AP. Development of a mild form of AP after ERCP is not considered a clinically relevant condition. Differences in the clinical presentation and prognosis of the mild and severe forms have been found between non-ERCP AP and post-endoscopic pancreatitis (PEP). It has been proposed that AP and PEP may also have different immunological responses to the initial injury. In this review, we summarise the literature on clinical and inflammatory processes in PEP vs non-ERCP AP.

NFκB-Mediated Invasiveness in CD133+ Pancreatic TICs Is Regulated by Autocrine and Paracrine Activation of IL1 Signaling

Tumor-initiating cells (TIC) have been implicated in pancreatic tumor initiation, progression, and metastasis. Among different markers that define this cell population within the tumor, the CD133⁺ cancer stem cell (CSC) population has reliably been described in these processes. CD133 expression has also been shown to functionally promote metastasis through NF-κB activation in this population, but the mechanism is unclear. In the current study, overexpression of CD133 increased expression and secretion of IL1β (IL1B), which activates an autocrine signaling loop that upregulates NF-κB signaling, epithelial-mesenchymal transition (EMT), and cellular invasion. This signaling pathway also induces CXCR4 expression, which in turn is instrumental in imparting an invasive phenotype to these cells. In addition to the autocrine signaling of the CD133 secreted IL1β, the tumor-associated macrophages (TAM) also produced IL1β, which further activated this pathway in TICs. The functional significance of the TIC marker CD133 has remained elusive for a very long time; the current study takes us one step closer to understanding how the downstream signaling pathways in these cells regulate the functional properties of TICs.Implications: This study demonstrates the important role of tumor- and macrophage-derived IL1β stimulation in pancreatic cancer. IL1 signaling is increased in cells with CD133 expression, leading to increased NF-kB activity, EMT induction, and invasion. Increased invasiveness via IL1β stimulation is mediated by the upregulation of CXCR4 expression. The study highlights the importance of IL1-mediated signaling in TICs. Mol Cancer Res; 16(1); 162-72. ©2017 AACR.

Intravenous hMSCs Ameliorate Acute Pancreatitis in Mice via Secretion of Tumor Necrosis Factor-α Stimulated Gene/Protein 6

The administration of mesenchymal stem cells/multipotent mesenchymal stromal cells (MSCs) to enhance tissue repair is currently undergoing clinical trials. Some studies, including our previous work, have also revealed the beneficial effect of MSCs in severe acute pancreatitis (SAP); however, their mechanisms or mode of action remain controversial. In this study, we demonstrated that intravenously (i.v.)-administered human MSCs (hMSCs) remarkably promoted recovery from experimental SAP without significant engraftment of hMSCs in the damaged pancreas. Interestingly, we found that i.v.-administered hMSCs with knockdown of TSG-6 expression lost most of their anti-inflammatory effects and thus could not significantly ameliorate SAP. As expected, the effects of hMSCs were also duplicated by i.v. infusion of recombinant TSG-6. Furthermore, our results showed that the increase of oxidative stress, activation of the NLRP3 inflammasome and NF-κB signaling in SAP was substantially inhibited following administration of hMSCs or TSG-6, which was dependent on the presence of CD-44 receptors in acinar cells. In conclusion, our study, for the first time, revealed that novel mechanisms are responsible for the immunomodulatory effect of i.v. hMSCs.

Paeoniflorin ameliorates acute necrotizing pancreatitis and pancreatitis‑induced acute renal injury

Acute renal injury caused by acute necrotizing pancreatitis (ANP) is a common complication that is associated with a high rate of mortality. Paeoniflorin is the active ingredient of paeonia radix and exhibits a number of pharmacological effects, such as anti-inflammatory, anticancer, analgesic and immunomodulatory effects. The present study detected the potential treatment effects of paeoniflorin on acute renal injury induced by ANP in a rat model. The optimal dose of paeoniflorin for preventing acute renal injury induced by ANP was determined. Then, the possible protective mechanism of paeoniflorin was investigated. The serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were measured with enzyme-linked immunosorbent assay kits. Renal inflammation and apoptosis were measured by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The expression of nitric oxide in kidney tissues was also evaluated. The p38 mitogen-activated protein kinases (MAPKs) were measured by western blotting. The results shown that paeoniflorin may ameliorate acute renal injury following ANP in rats by inhibiting inflammatory responses and renal cell apoptosis. These effects may be associated with the p38MAPK and nuclear factor-κB signal pathway.

Intestinal microecology and pancreatitis

The intestinal symbiotic microbes and the human body depend on each other to form the intestinal microecology system of the human body. Symbiotic microorganisms play an important role in many diseases through the interaction between pathogens and host pattern recognition receptors. Pathogen-associated molecular pattern (PAMPs) and damage-associated molecular patterns (DAMPs) are involved in the progression of pancreatitis. Intestinal microecology plays an important role in the pathogenesis of pancreatitis. Acute pancreatitis, which is associated with intestinal barrier dysfunction and bacterial translocation, increases the risk of pancreatic infection and death. Infection with intestinal bacteria is related to the development of chronic pancreatitis, and it may induce autoimmune pancreatitis (AIP) by molecular modeling. Understanding the relationship between intestinal microecology and pancreatitis will provide guidance and direction for the diagnosis and treatment of pancreatitis.

Inflammasomes in pancreatic physiology and disease

In this review we summarize the role of inflammasomes in pancreatic physiology and disease with a focus on acute pancreatitis where much recent progress has been made. New findings have identified inducers of and cell specificity of inflammasome component expression in the pancreas, the contribution of inflammasome-regulated effectors to pancreatitis, and metabolic regulation of inflammasome activation, which are strong determinants of injury in pancreatitis. New areas of pancreatic biology will be highlighted in the context of our evolving understanding of gut microbiome- and injury-induced inflammasome priming, pyroptosis, and innate immune-mediated regulation of cell metabolism.

Recombinant interleukin-1 receptor antagonist attenuates the severity of chronic pancreatitis induced by TNBS in rats

Chronic pancreatitis (CP) is a common disease in the department of gastroenterology, with the main symptoms of exocrine and/or endocrine insufficiency and abdominal pain. The pathogenic mechanism of CP is still not fully clarified and the aims of treatment now are to relieve symptoms. In this study, we attempted to find a connection between interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1Ra) in trinitrobenzene sulfonic acid (TNBS)-induced chronic pancreatitis, and then the therapeutic effect of recombinant IL-1Ra was also detected in the CP model. Chronic pancreatitis was induced by intraductal infusion of TNBS in SD rats followed by a consecutive administration of rIL-1Ra, and the histological changes and collagen content in the pancreas were measured, as well as the abdominal hypersensitivity. We found that rhIL-1Ra could attenuate the severity of chronic pancreatic injury, modulate the extracellular matrix secretion, focal proliferation and apoptosis, and cellular immunity in TNBS-induced CP. Interestingly, rIL-1Ra could also block the pancreatitis-induced referred abdominal hypersensitivity. In conclusion, IL-1Ra may play a protective role in CP and rIL-1Ra would be a potential therapeutic target for the treatment of CP, while its possible mechanisms and clinical usage still need further investigation.

Roles of Commensal Microbiota in Pancreas Homeostasis and Pancreatic Pathologies

The pancreas plays a central role in metabolism, allowing ingested food to be converted and used as fuel by the cells throughout the body. On the other hand, the pancreas may be affected by devastating diseases, such as pancreatitis, pancreatic adenocarcinoma (PAC), and diabetes mellitus (DM), which generally results in a wide metabolic imbalance. The causes for the development and progression of these diseases are still controversial; therefore it is essential to better understand the underlying mechanisms which compromise the pancreatic homeostasis. The interest in the study of the commensal microbiome increased extensively in recent years, when many discoveries have illustrated its central role in both human physiology and maintenance of homeostasis. Further understanding of the involvement of the microbiome during the development of pathological conditions is critical for the improvement of new diagnostic and therapeutic approaches. In the present review, we discuss recent findings on the behavior and functions played by the microbiota in major pancreatic diseases and provide further insights into its potential roles in the maintenance of pancreatic steady-state activities.

Immune-modulating therapy in acute pancreatitis: Fact or fiction

Acute pancreatitis (AP) is one of the most common diseases of the gastrointestinal tract, bearing significant morbidity and mortality worldwide. Current treatment of AP remains unspecific and supportive and is mainly targeted to aggressively prevent systemic complications and organ failure by intensive care. As acute pancreatitis shares an indistinguishable profile of inflammation with sepsis, therapeutic approaches have turned towards modulating the systemic inflammatory response. Targets, among others, have included pro- and anti-inflammatory modulators, cytokines, chemokines, immune cells, adhesive molecules and platelets. Even though, initial results in experimental models have been encouraging, clinical implementation of immune-regulating therapies in acute pancreatitis has had a slow progress. Main reasons include difficulty in clinical translation of experimental data, poor understanding of inflammatory response time-course, flaws in experimental designs, need for multimodal approaches and commercial drawbacks. Whether immune-modulation in acute pancreatitis remains a fact or just fiction remains to be seen in the future.

Effectiveness of interleukin-1 receptor antagonist (Anakinra) on cerulein-induced experimental acute pancreatitis in rats

AIM

Acute pancreatitis (AP) is defined as an inflammatory disease of the pancreas. The purpose of this study was to examine the effectiveness of Anakinra on cerulein-induced experimental pancreatitis rat model by using the results of biochemical and histopathological findings.

MATERIALS AND METHODS

Cerulein was administered to induce AP in rats. Group 1 was the sham group. Subcutancerulein was injected to the rats in group 2 for experimental pancreatitis group. In groups 3 and 4, 100 and 50 mg/kg intraperitoneal Anakinra were injected after the induction of experimental pancreatitis by subcutaneous cerulein in rats, respectively. Lastly, in group 5, rats were injected with intraperitoneal saline and subcutan cerulean for placebo group. The following parameters were evaluated: histopathological score of pancreatitis, apoptotic index, amylase, lipase, TNF-α levels, IL-1β and the leukocyte count.

RESULTS

When the results of serum amylase, lipase, TNF-α and IL-1β levels, the leukocyte count, histopathologic scores and apoptotic indices of control group compared to the results of other groups, the differences exhibited statistical significance (all p < 0.05). On the other hand, when the results of fourth group compared with the results of third group, the data demonstrated statistical insignificance (p > 0.05). However, no any significant differences were found between the results of fourth and fifth groups (p > 0.05).

CONCLUSION

In the light of these results, cerulein is an appropriate agent for experimental AP rat model and Anakinra has a favorable therapeutic effect on acute experimental pancreatitis model. Moreover, Anakinra significantly decreases cerulein-related pancreatic tissue injury and pancreatic apoptosis.

Serum M30 and M65 levels and effects of Ankaferd blood stopper in cerulein induced experimental acute pancreatitis model in rats

BACKGROUND AND AIM

The incidence of acute pancreatitis is increasing recently. The aim of this study is to investigate the effect of Ankaferd Blood Stopper (ABS) on experimental model of cerulein induced acute pancreatitis in rats.

MATERIALS AND METHODS

Forty Wistar Albino rats were divided into five groups. Group 1: Sham (n = 8), Group 2: Control group (n = 8), Group 3: Treatment group (n = 8), Group 4: Prophylaxis group (n = 8), Group 5: Prophylaxis treatment group (n = 8). Any practice was not administered to Group 1. Rats were treated with either 1 ml ABS or 1 ml saline via intraperitoneal route before and after inducing acute pancreatitis. Pancreatic tissues were examined histopathologically. Amylase, cytokines (tumor necrosis factor-α and interleukin-1β), and markers of apoptosis (M30 and M65) were also measured in blood samples. Immunohistochemical staining was performed with caspase 3 antibody.

RESULTS

We found a statistically significant improvement in histopathological scores in treatment group and prophylaxis group compared with controls. In treatment group, M30 and M65 levels were lower when compared with controls. In prophylaxis group, there was not a statistically significant difference in M30 levels, but M65 levels were lower when compared with controls.

CONCLUSION

In this experimental acute pancreatitis model, we found high histopathological healing effects of ABS treatment and also prophylaxis. ABS treatment and prophylaxis reduced apoptosis.

Sterile inflammation in the liver and pancreas

The ability of tissue injury to result in inflammation is a well-recognized phenomenon and is central to a number of common liver and pancreatic diseases including alcoholic steatohepatitis and pancreatitis, as well as drug-induced liver injury, non-alcoholic steatohepatitis, and pancreatitis from other causes. The requirements of extracellular damage-associated molecules and a cytosolic machinery labeled the inflammasome have been established in in vitro culture systems and in vivo disease models. This has provided a generic insight into the pathways involved, and the challenge now is to understand the specifics of these mechanisms in relation to the particular insults and organs involved. One reason for the excitement in this field is that a number of therapeutic candidates such a toll-like receptor antagonists and interleukin-1R antagonists are either approved or in clinical trials for other indications.

Rhubarb attenuates the severity of acute necrotizing pancreatitis by inhibiting MAPKs in rats

AIM

To investigate the effect of rhubarb on MAPK activation in sodium taurocholate-induced pancreatitis in rats.

METHODS

All rats were randomly divided into three groups: control, acute pancreatitis (AP) and rhubarb treatment groups. The MAPK activation was detected by western blotting. The levels of TNFα and IL6 in serum were estimated by ELISA. The pathological changes of the pancreas were examined microscopically.

RESULTS

It was found that hemorrhage, exudates and infiltration of inflammatory cells in the pancreas were significantly less in the rhubarb group than in the AP group. In the AP group, the activation of MAPKs in pancreatic tissues was enhanced significantly at every time point compared with the control group and the levels of TNFα and IL6 were also increased. Rhubarb treatment markedly inhibited activation of MAPKs concomitantly with inhibition of TNFα and IL6 expression.

CONCLUSION

We suggest that rhubarb probably attenuates AP by inhibiting activation of MAPKs and expression of inflammatory mediators.

The ST2 pathway is involved in acute pancreatitis: a translational study in humans and mice

Acute pancreatitis (AP) is an inflammatory disease in which the regulatory pathways are not clearly elucidated. Activation of interleukin 1β (IL-1β) and immunomodulation via MyD88, the first signaling molecule in the ST2 pathway, seem to be involved. Because IL-33, the ST2 ligand, is an IL-1 family member and acts as an alarmin, we explored the ST2 pathway in human and mouse AP. Soluble ST2 was assayed by enzyme-linked immunosorbent assay (ELISA) in plasma of 44 patients admitted for AP. The levels of soluble ST2 increased early during AP and correlated with parameters of severity. Under two different experimental models of AP (ie, choline-deficient-ethionine-supplemented diet and cerulein injections), ST2-deficient mice (Il1rl1(-/-)) presented with more severe disease than wild-type mice, with increased activation of mast cells. In vitro, Il1rl1(-/-) bone-marrow-derived mast cells exhibited exacerbated degranulation, compared with the wild type. Flow cytometry identified mast cells as the main peritoneal population expressing ST2. Using immunohistochemistry and ELISA, we showed constitutive expression of IL-33 in murine pancreas and its release during experimental AP. Correlated with AP severity, increased soluble ST2 levels evoke involvement of the ST2 pathway in human AP. Furthermore, our experimental data suggest a protective role for ST2 during AP, highlighting the potential regulatory role of mast cells and the possibility of the ST2 pathway as a new therapeutic target in AP.

Sterile inflammatory response in acute pancreatitis

The initial injury in acute pancreatitis is characteristically sterile and results in acinar cells necrosis. Intracellular contents released from damaged cells into the extracellular space serve as damage-associated molecular patterns (DAMPs) that trigger inflammation. There is increasing evidence that this sterile inflammatory response mediated through DAMPs released from necrotic acinar cells is a key determinant of further pancreatic injury, remote organ injury, and disease resolution in experimental models. A number of DAMPS, including high-mobility group box protein 1, DNA, adenosine triphosphate and heat shock protein 70, have been shown to have a role in experimental pancreatitis. Many of these DAMPs are also detectable in the human pancreatitis. Genetic deletion and pharmacologic antagonism demonstrate that specific DAMP receptors, including Toll-like receptor (TLR) 4, TLR9, and P2X7, are also required for inflammation in experimental acute pancreatitis. Downstream DAMP-sensing components include nod-like receptor protein 3, caspase 1, interleukin-1β (IL-1), IL-18, and IL-1 receptor, and also are required for full experimental pancreatitis. These DAMP-mediated pathways provide novel therapeutic targets using antagonists of TLRs and other receptors.

Recombinant human interleukin-1 receptor antagonist (rhIL-1Ra) attenuates caerulein-induced chronic pancreatitis in mice

Chronic pancreatitis is a progressive inflammatory disease featuring irreversible irregular scarring of the exocrine parenchyma characterized by acinar destruction and fibrosis subsequent to inflammation in the pancreas. Despite decades of research, the knowledge is limited to the treatment of this disease. After finding a connection between interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1Ra) in caerulein-induced chronic pancreatitis, we assumed that recombinant human IL-1Ra (rhIL-1Ra), the natural antagonist of IL-1β, might have a protective role in chronic pancreatitis in mice. Chronic pancreatitis was induced by repetitive intraperitoneal injections of caerulein in C57/BL mice followed by a consecutive administration of rhIL-1Ra (10mg/kg). Collagen content and histological changes in the pancreas as well as serum amylase and lipase were measured. We found that rhIL-1Ra significantly decreased the hydroxyproline and the fibrotic area in the pancreas after the caerulein challenge. Caerulein-induced serum amylase elevation and tissue damage were also attenuated in rhIL-1Ra treated mice. Our results reveal a potential role of rhIL-1Ra in protecting mice against caerulein-induced chronic pancreatitis and lead to a conclusion that this protein may be a potential candidate agent for the treatment of chronic pancreatitis in humans.

Panhematin provides a therapeutic benefit in experimental pancreatitis

BACKGROUND AND AIM

Acute pancreatitis (AP) can result in pancreatic necrosis and inflammation, with subsequent multi-organ failure. AP is associated with increased neutrophil recruitment and a rise in pro-inflammatory cytokines such as TNFα. Pretreatment with haemin, results in recruitment of haem-oxygenase-1 (HO-1)(+) macrophages and protects against experimental pancreatitis. It is not clear whether modulation of HO-1 after onset of disease has a protective role. In this study, we tested the utility of Panhematin, a water-soluble haemin formulation, in activating and inducing pancreatic HO-1, and as a therapeutic agent in treating mouse acute pancreatitis.

METHODS

We defined the distribution of radiolabelled haemin, then used in vivo HO-1-luciferase bioluminescence imaging and the CO-release assay to test Panhematin-induced upregulation of HO-1 transcription and activity, respectively. Using two well-defined AP murine models, we tested the therapeutic benefit of Panhematin, and quantified cytokine release using a luminex assay.

RESULTS

Intravenously administered Panhematin induces rapid recruitment of HO-1(+) cells to the pancreas within 2 h and de novo splenic HO-1 transcription by 12 h. Despite high baseline spleen HO-1 activity, the pancreas is particularly responsive to Panhematin-mediated HO-1 induction. Panhematin-treated mice, at various time points after AP induction had significant reduction in mortality, pancreatic injury, together with upregulation of HO-1 and downregulation of pro-inflammatory cytokines and CXCL1, a potent neutrophil chemoattractant.

CONCLUSIONS

Despite AP-associated mortality and morbidity, no effective treatment other than supportive care exists. We demonstrate that Panhematin leads to: (i) rapid induction and activation of pancreatic HO-1 with recruitment of HO-1(+) cells to the pancreas, (ii) amelioration of AP even when given late during the course of disease, and (iii) a decrease in leucocyte infiltration and pro-inflammatory cytokines including CXCL1. The utility of Panhematin at modest doses as a therapeutic in experimental pancreatitis, coupled with its current use and safety in humans, raises the potential of its applicability to human pancreatitis.

Anti-inflammatory effects of peritoneal lavage in acute pancreatitis

OBJECTIVES

Intraperitoneal administration of trypsin stimulates the production of cytokines from peritoneal macrophages. Removing the pancreatitis-associated ascitic fluid from the peritoneal cavity may decrease the systemic inflammatory response in acute pancreatitis (AP). We investigated the effect of peritoneal lavage on the systemic inflammatory response in severe AP.

METHODS

Acute pancreatitis was induced in Wistar rats by 5% taurocholate intraductal injection. Peritoneal lavage was performed for 4 hours after onset of AP. At 4 hours after induction of AP, serum samples were assayed for amylase and inflammatory cytokines (tumor necrosis factor α, interleukin-6 [IL-6], and IL-10). Expression of pancreatic cyclooxygenase-2 and inducible nitric oxide synthase, liver mitochondrial function, and pulmonary myeloperoxidase activities were determined.

RESULTS

Peritoneal lavage after AP led to a decrease in serum levels of tumor necrosis factor α and IL-6 and an increase in IL-10. In the pancreas, this treatment reduced cyclooxygenase-2 and inducible nitric oxide synthase expression. Liver mitochondrial dysfunction was also reduced. There were no differences on serum amylase levels and pulmonary myeloperoxidase between groups with AP.

CONCLUSIONS

Peritoneal lavage has a systemic anti-inflammatory effect in severe AP and may be able to decrease the severity of severe AP.

Antioxidant inhibits HMGB1 expression and reduces pancreas injury in rats with severe acute pancreatitis

BACKGROUND

Pathogenesis of severe acute pancreatitis is still unclear, which leads to a lack of proper treatment in severe acute pancreatitis therapeutic strategy.

OBJECTIVE

To investigate the effect of treatment with antioxidant pyrrolidine dithiocarbamate on pancreas injury in rats with severe acute pancreatitis and its possible mechanism.

METHODS

A total of 144 male Sprague-Dawley rats were randomly allocated into a sham operation group (n=48), a severe acute pancreatitis group (n=48), and a pyrrolidine dithiocarbamate-treated group (n=48). All the rats were killed at 1, 3, 6, 12, 24, and 48 h after operation. The pancreas histopathologies were observed and serum amylase levels were tested. Meanwhile, the nuclear factor-kappaB activation, tumor necrosis factor-alpha levels and high-mobility group box protein-1 expression levels in pancreatic tissue were studied.

RESULTS

Animals receiving pyrrolidine dithiocarbamate had significantly improved pancreas histopathology and lower serum amylase levels (p<0.05). In the severe acute pancreatitis group, pancreas tumor necrosis factor-alpha levels reached a peak at 6 h after operation and afterwards rapidly declined to normal levels. However, high-mobility group box protein-1 levels in pancreatic tissue increased remarkably at the 12th hour, reached a peak at 24 h, and maintained up to 48 h post-severe acute pancreatitis. Compared to the severe acute pancreatitis group, the pancreas nuclear factor-kappaB activity, tumor necrosis factor-alpha, high-mobility group box protein-1 levels in the pyrrolidine dithiocarbamate-treated group all remarkably decreased (p<0.05).

CONCLUSIONS

High-mobility group box protein-1 seems to act as a late cytokine mediator in the pathogenesis of severe acute pancreatitis. Pyrrolidine dithiocarbamate might inhibit the activation of nuclear factor-kappaB to blockade tumor necrosis factor-alpha, thereby indirectly suppressing the high-mobility group box protein-1 and reducing pancreatic tissue damage in rats with severe acute pancreatitis.

The pathogenic mechanism of severe acute pancreatitis complicated with renal injury: a review of current knowledge

The onset of severe acute pancreatitis (SAP) is clinically harmful as it may rapidly progress from a local pancreatic inflammation into proemial systemic inflammatory reactions. Patients with SAP have a high mortality, with most cases of death resulting from complications involving the failure of organs other than the pancreas. The distinctive feature of SAP is that once it starts, it may aggrevate the clinical condition of the patient continuously, so that the levels of injury to the other organs surpass the severity of the pancreatic lesion, even causing multiple organ failure and, ultimately, death. In clinical practice, the main complications in terms of organ dysfunctions are shock, acute respiratory failure, acute renal failure, among others. The acute renal injury caused by SAP is not only able to aggravate the state of pancreatitis, but it also develops into renal failure and elevates patients' mortality. Studies have found that the injury due to massive inflammatory mediators, microcirculation changes and apoptosis, among others, may play important roles in the pathogenic mechanism of acute renal injury.

Progress of study on the relationship between mediators of inflammation and apoptosis in acute pancreatitis

As an important pathological feature of acute pancreatitis, apoptosis may occur in multiple organs and relate directly to the progression of disease. It is mainly controlled by the apoptosis gene and also influenced by inflammatory mediators. We summarize here the roles of the main inflammatory mediators (e.g., NO, TNF-alpha, TGF-beta1, IL-10, NF-kappaB) during the pathologic process of acute pancreatitis.

Adjusting effects of baicalin for nuclear factor-kappaB and tumor necrosis factor-alpha on rats with caerulein-induced acute pancreatitis

Forty Wistar rats were divided into 5 groups, including the control group, the acute pancreatitis group (AP group, induced by intraperitoneal injections of caerulein), and the AP group treated with baicalin, the AP group treated with LPS, and the AP group treated with LPS and baicalin. Pathological damage of pancreatic tissue was scored with hematoxylin and eosin (HE) staining. The mRNA expression of TNF-α was measured with semiquantitative RT-PCR, and activation of NF-κB was detected with flow cytometry assay. It was shown in the results that the expression of TNF-α mRNA, activation of NF-κB, and pathological score of AP group were all obviously higher than those of control group (P < .01). In AP group treated with LPS, further rise of these values were observed (P < .01). In the AP group treated with baicalin, activation of NF-κB decreased (P < .05), and expression of TNF-α mRNA also obviously decreased (P < .01), while pancreatic pathological damage was alleviated at the same time (P < .01); similar results were observed in AP group treated with LPS and baicalin (P < .01), which indicated that baicalin might be applied to inhibit NF-κB activating and TNF-α expressing so as to treat AP.

Acute pancreatitis: models, markers, and mediators

Acute pancreatitis has an incidence of approximately 40 cases per year per 100,000 adults. Although usually self-limiting, 10% to 20% of afflicted patients will progress to severe pancreatitis. The mortality rate among patients with severe pancreatitis may approach 30% when they progress to multisystem organ failure. The development of acute pancreatitis illustrates the requirement for understanding the basic mechanisms of disease progression to drive the exploration of therapeutic options. The pathogenesis of acute pancreatitis involves the interplay of local and systemic immune responses that are often difficult to characterize, particularly when results from animal models are used as a foundation for human trials. Experimental studies suggest that the prognosis for acute pancreatitis depends upon the degree of pancreatic necrosis and the intensity of multisystem organ failure generated by the systemic inflammatory response. This suggests an intricate balance between localized tissue damage with proinflammatory cytokine production and a systemic, anti-inflammatory response that restricts the inappropriate movement of proinflammatory agents into the circulation. The critical players of this interaction include the proinflammatory cytokines IL-1beta, TNF-alpha, IL-6, IL-8, and platelet activating factor (PAF). The anti-inflammatory cytokines IL-10, as well as TNF-soluble receptors and IL-1 receptor antagonist, have also been shown to be intimately involved in the inflammatory response to acute pancreatitis. Other compounds implicated in disease pathogenesis in experimental models include complement, bradykinin, nitric oxide, reactive oxygen intermediates, substance P, and higher polyamines. Several of these mediators have been documented to be present at increased concentrations in the plasma of patients with severe, acute pancreatitis. Preclinical work has shown that some of these mediators are markers for disease activity, whereas other inflammatory components may actually drive the disease process as important mediators. Implication of such mediators suggests that interruption or blunting of an inappropriate immune response has the potential to improve outcome. Although the manipulations of specific mediators in animal models may be promising, they may not transition well to the human clinical setting. However, continued reliance on experimental animal models of acute pancreatitis may be necessary to determine the underlying causes of disease. Full understanding of these basic mechanisms involves determining not only which mediators are present, but also closely documenting the kinetics of their appearance. Measurement of the inflammatory response may also serve to identify diagnostic markers for the presence of acute pancreatitis and provide insight into prognosis. Understanding the models, documenting the markers, and deciphering the mediators have the potential to improve treatment of acute pancreatitis.

Effects of Chaishao Chengqi decoction with ginkgo biloba leaf on lung injury induced by severe acute pancreatitis

AIM: To explore the preventive and therapeutic effects of Chaishao Chengqi decoction (CCD) with ginkgo biloba leaf (GBL) on the lung injury induced by severe acute pancreatitis (SAP).

METHODS: A total of 65 SAP patients were divided into group A (n = 35) and B (n = 30). Besides internal treatment, the patients in group A also received CCD plus GBL. The occurrence of hypoxemia, duration of abdominal pain-relief, recovering time of borborygmus, local complications, and mortality rate as well as the level changes of serum platelet-activating factor (PAF), tumor necrosis factor-a (TNF-a), and interleukin-1 (IL-1) 72 h after treatment were observed, respectively. Upper abdominal spiral CT scanning was used to evaluate the degrees of severe acute pancreatitis.

RESULTS: The incidence rates of hypoxemia and acute respiratory distress syndrome were significantly lower group A than those in group B (45.71% vs 73.33%, P < 0.05; 8.57% vs 30%, P < 0.05). The serum levels of inflammatory factors dropped markedly in group A 72 h after treatment (PAF: 4.45 ± 1.25 → 2.83 ± 1.64 mg/L, P < 0.01; TNF-a: 32.96 ± 4.33 → 27.82 ± 5.26 ng/L, P < 0.01; IL-1: 3.46 ± 1.07 → 2.51 ± 0.52 ng/L, P < 0.01), but they had no changes in group B. The duration of abdominal pain-relief, recovering time of borborygmus and progressive proportion of pancreatic inflammation were decreased in group A as compared with those in group B (P < 0.05). The rates mortality and local complications were 0 and 2.86% in group A, and 10% and 13.33% in group B, respectively.

CONCLUSION: CCD plus GBL has preventive and therapeutic action on the SAP-induced lung injury, and the mechanism is probably related to its inhibition on the secretion of inflammatory mediators.

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Inhibition of Experimental Autoimmune Anterior Uveitis by Adenovirus-Mediated Transfer of the Interleukin-10 Gene

AIMS

The aim of this study was to investigate the efficiency of adenoviral-mediated transfer of the interleukin (IL)-10 gene for inhibition of experimental autoimmune anterior uveitis, a rat model of human acute anterior uveitis. Uveitis was induced in the Lewis rat by simultaneous injection of melanin-associated antigen intraperitoneally (i.p.) and into the left footpad. The animals were treated by systemic administration of adenoviral construct expressing IL-10 (Ad-IL-10) or Ad-Mock carrying no cytokine transgene.

RESULTS

A significant reduction in ocular inflammation was noted for rats that received one or two divided i.p. administrations of Ad-IL-10 (one 10 x 10(9) and two 5 x 10(9) particles of adenoviral construct, respectively), as judged by reduced clinical scores and decreased leukocyte infiltration in the anterior chamber and confirmed by histological examinations, relative to control animals. Systemic Ad-IL-10, treatment also revealed a higher serum level of IL-10, compared to the controls.

CONCLUSIONS

The results suggest that systemic adenovirus-mediated IL-10 gene therapy has an anti-inflammatory effect on immune-mediated ocular inflammation and that this approach may be promising for the treatment of acute anterior uveitis.

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Association of polymorphisms of IL and CD14 genes with acute severe pancreatitis and septic shock

AIM: To investigate IL-1b+3 594 in the 5^th intron, IL-10-1 082 and CD14-159 polymorphisms in patients with acute pancreatitis (AP) and septic shock.

METHODS: The study included 215 patients (109 with acute severe pancreatitis (SAP), 106 with acute mild pancreatitis (MAP)) and 116 healthy volunteers. Genomic DNA was prepared from peripheral blood leukocytes. Genotypes and allele frequencies were determined in patients and healthy controls using restriction fragment length polymorphism analysis of PCR products.

RESULTS: The frequencies of IL-1b+3 594T, IL-10-1082G and CD14-159T allele were similar in patients with mild or severe pancreatitis and in controls. Within SAP patients, no significant differences were found in the allele distribution examined when etiology was studied again. Patients with septic shock showed a significantly higher prevalence of IL-10-1082G allele than those without shock (c² = 5.921, P = 0.015).

CONCLUSION: IL-10-1082G plays an important role in the susceptibility of SAP patients to septic shock. Genetic factors are not important in determination of disease severity or susceptibility to AP.

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The usefulness of laboratory tests in the early assessment of severity of acute pancreatitis

Acute pancreatitis is a disorder that affects approximately 200,000 individuals in the U.S. annually. While most cases are mild, up to 30% of patients will have a complicated course with prolonged hospitalization and significant morbidity and mortality. Early institution of several therapeutic interventions, such as enteral nutrition, prophylactic antibiotics, endoscopic retrograde cholangiopancreatography (ERCP) and intensive care monitoring, have been shown to decrease the morbidity associated with severe acute pancreatitis. However, the ability of clinicians to predict, upon presentation, which patient will have mild or severe pancreatitis has remained poor over the years, thus leading to a delay in the institution of such treatments. Researchers have focused on markers that might improve upon clinical prediction alone. While data have shown the predictive value of tools such as Ranson's and Glasgow's criteria, C-reactive protein (CRP) and the APACHE score, their application in clinical practice has been limited by a time delay of at least 48 h in the former two and by being cumbersome in the latter. Thus, our focus is to critically appraise the evidence available for various biochemical markers in their ability to distinguish mild and severe acute pancreatitis early and more accurately than currently available tools.

Cyclooxygenase-2 gene disruption attenuates the severity of acute pancreatitis and pancreatitis-associated lung injury

BACKGROUND & AIMS

Cyclooxygenase (COX) catalyzes the rate-limiting step in prostaglandin production; the inducible isoform, COX-2, has been implicated in a variety of inflammatory processes. The role of COX in acute pancreatitis and pancreatitis-associated lung injury is not known.

METHODS

Acute pancreatitis was induced in Swiss Webster mice or mice deficient in the COX-2 (Ptgs2) or the COX-1 (Ptgs1) genes. Pancreata and lungs were harvested, and histologic sections of these tissues were scored. COX-2 expression, myeloperoxidase activity (a measurement of neutrophil sequestration), and serum amylase levels were determined.

RESULTS

Acute pancreatitis was associated with induction of COX-2 expression. Treatment with NS-398 (a COX-2 inhibitor) significantly decreased the severity of pancreatitis. Furthermore, Ptgs2-deficient mice showed minimal histologic evidence of pancreatitis, a marked attenuation in the severity of lung injury, and a significant reduction in myeloperoxidase activity. In contrast, Ptgs1-deficient mice had pancreatitis and pulmonary inflammation, which was as severe or, in some instances, more severe than in the wild-type mice.

CONCLUSIONS

Inhibition of COX-2 by either pharmacologic inhibition or selective genetic deletion markedly attenuated the severity of acute pancreatitis. Our findings identify the COX-2 isoform as an important regulator of the severity of acute pancreatitis and pancreatitis-associated lung injury.

Human interleukin 10 gene therapy decreases the severity and mortality of lethal pancreatitis in rats

BACKGROUND

Studies have proven the validity of interleukin-10 (IL-10) in the treatment of experimental pancreatitis. Prophylactic human IL-10 (hIL-10) gene treatment attenuated the severity in cerulein models. Our research aims to study whether the therapeutic hIL-10 gene could decrease both severity and mortality in a lethal pancreatic model.

METHODS

Severe acute pancreatitis (SAP) was induced by sodium taurocholate. A plasmid-hIL-10 construct (pcDNA3-hIL-10) complexed with cationic liposomes was administered to SAP rats by a single intraperitoneal injection. Levels of hIL-10 in the pancreas, liver, and lungs were determined by ELISA kits. The severity of pancreatitis was assessed in terms of serum amylase, histology, and tissue tumor necrosis factor alpha (TNF-alpha). Mortality, observed for 7 days, was evaluated for gene therapy or control groups.

RESULTS

After hIL-10 gene therapy, hIL-10 levels in the pancreas, liver, and lungs increased significantly and the serum amylase, tissue TNF-alpha, and histological changes in pancreas, liver, and lungs decreased markedly. Therefore, mortality was significantly reduced in the hIL-10 gene therapy group, in which 70% of rats survived in the 7-day observation, while only 10% survived in untreated groups (P < 0.05).

CONCLUSION

We found that liposome/hIL-10 gene therapy decreased severity and mortality in SAP, even carried out after SAP establishment, predicting a more convenient shift to clinical applications.

Therapeutic application of caspase 1/interleukin-1beta-converting enzyme inhibitor decreases the death rate in severe acute experimental pancreatitis

OBJECTIVE

To assess the effect of therapeutic inhibition of interleukin 1beta-converting enzyme (ICE) in an experimental model of severe acute pancreatitis (SAP).

SUMMARY BACKGROUND DATA

Several lines of evidence suggest that cytokines activated by ICE play an instrumental role in the course of acute pancreatitis. Recent studies have shown that pharmacologic or genetic blockade of ICE significantly ameliorates the overall severity of and the death rate in SAP.

METHODS

Severe acute pancreatitis was induced by infusion of 5% sodium taurocholate in Wistar rats. A new, highly selective, irreversible inhibitor of ICE was intraperitoneally applied at a dosage of 0.25 mg every 12 hours. Control animals in group 1 received treatment with saline; in group 2 rats, ICE inhibition was started 6 hours after the onset of pancreatitis; and in group 3 rats, ICE inhibition was started 12 hours after the onset of pancreatitis. After a 7-day observation period, surviving rats were killed and blood, plasma, pancreas, lung, and liver were used for subsequent analysis.

RESULTS

Inhibition of ICE decreased the 7-day death rate from 87.5% to 38.9% irrespective whether treatment was started 6 hours or 12 hours after induction of SAP. Morphometric analysis revealed a significant reduction of acinar cell necrosis in both treated groups, whereas pancreatitis-associated pulmonary and hepatic damage was uniformly low and not influenced by ICE inhibition. Tissue myeloperoxidase concentrations were dramatically decreased in the pancreas and the lung after either regimen of ICE inhibitor treatment. In contrast to lung and liver, marked upregulation of interleukin 1beta, tumor necrosis factor alpha, and ICE mRNA was observed in the pancreas, with levels of interleukin 1beta and tumor necrosis factor alpha being reduced in ICE-inhibited animals. Compared with nontreated rats, plasma amylase levels were higher in both treatment groups, whereas lipase and hematocrit showed no difference. Changes of the differential white blood count including neutrophils, lymphocytes, and monocytes were attenuated in both groups after ICE inhibitor treatment.

CONCLUSIONS

Pharmacologic inhibition of ICE significantly improves the overall severity of and the death rate in SAP. A substantial reduction of neutrophil-mediated tissue injury in pancreas and lung seems to contribute to the beneficial effects of this approach. Moreover, ICE inhibition is still effective after a therapeutic window of 12 hours. Based on the current findings, future studies on the clinical application of ICE-inhibiting substances in acute pancreatitis seem to be promising.

Randomized, placebo-controlled trial of lazaroid effects on severe acute pancreatitis in rats

OBJECTIVES

To evaluate the therapeutic potential of lazaroids in severe necrotizing acute pancreatitis and to investigate the association between oxidative stress, protease activation, and local production of proinflammatory cytokines and the severity and lethality of the disease.

BACKGROUND

Oxidative stress is a crucial factor in the pathophysiology of acute pancreatitis and its systemic complications. Treatment with antioxidants, however, failed to improve survival in most studies performed so far. Lazaroids are a novel class of antioxidants that potently protect pancreatic acinar cells against oxidant attack in vitro.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

University research laboratory.

SUBJECTS

Seventy-five anesthetized male Wistar rats (300-350 g).

INTERVENTIONS

Severe acute pancreatitis was induced by retrograde injection of 3.5% taurocholate-sodium into the common bile-pancreatic duct. Interventions were performed to mimic the clinical situation, including continuous intravenous fluid substitution and administration of lazaroids in a therapeutic protocol. Therapy was started 1 hr after injection of the bile salt by using three different lazaroids, lactated Ringer's solution (placebo), and methylprednisolone as a corticosteroid control (n = 15 in each group). All the substances were given by continuous intravenous infusion throughout the 20-hr trial period.

MEASUREMENTS AND MAIN RESULTS

Pancreatic homogenates and ascites were analyzed for indicators of oxidative stress, antioxidants, proteases, and proinflammatory cytokines. Pancreatic edema, morphologic pancreatitis severity, and pancreatic histopathology also were assessed. All three lazaroids and methylprednisolone diminished pancreatic tumor necrosis factor-alpha concentrations. Lethality was 33% in the placebo group. Neither the lazaroids nor methylprednisolone influenced survival. The local pancreatic and peritoneal concentrations of lipid peroxidation products, antioxidants, and proteases did not differ among the five groups. Nonsurviving rats, however, had a higher total protease activity in the pancreas and higher concentrations of trypsinogen activation peptide in ascites, as compared with surviving animals. There were no differences between survivors and nonsurvivors with regard to variables of oxidative stress and cytokines.

CONCLUSIONS

Lazaroid application under clinically relevant conditions (i.e., after induction of fulminant acute pancreatitis) does not influence lethality or biochemical variables relevant to this disease. Protease activation rather than oxidative stress or local pancreatic cytokine production is an important determinant of disease severity and survival in acute pancreatitis. In experimental studies evaluating novel therapeutics, the same strict criteria should be applied as in the human setting.

Recombinant human interleukin-11 decreases severity of acute necrotizing pancreatitis in mice

Interleukin (IL)-11 has anti-inflammatory activity in animal models of gut inflammation, endotoxemia, and radiation-induced thoracic injury. The aim of the present study was to investigate the protective role of IL-11 in a model of acute necrotizing pancreatitis in mice. Acute pancreatitis was induced by administration of seven intraperitoneal injections of cerulein (50 microg/kg) at hourly intervals. Lipopolysaccharide (LPS) was injected 5 hours after the first cerulein injection. Treatment with recombinant human IL-11 (rhIL-11) was started 30 minutes before the first cerulein injection and repeated 4 hours later. Serum levels of amylase, lipase, and tumor necrosis factor (TNF)-alpha were measured at the end of the experiments. The severity of pancreatitis was evaluated by histological scoring using a semiquantitative analysis of hematoxylin and eosin-stained sections of the pancreas. Competitive reverse transcription-polymerase chain reaction (RT-PCR) was performed to quantify the intrapancreatic TNF-alpha mRNA levels. Serum amylase and lipase levels progressively increased with a maximum reached between 8 and 11 hours. Treatment with rhIL-11 significantly decreased amylase and lipase levels at 6 and 8 hours. Serum TNF-alpha peaked at 6 hours and rapidly decreased thereafter. The elevation of serum TNF-alpha was markedly inhibited by treatment with rhIL-11. Histologically, treatment of rhIL-11 reduced the severity of pancreatic injury including edema, inflammatory cell infiltration, and hemorrhage at 6 hours. Intrapancreatic TNF-alpha mRNA levels were reduced by >50% in the rhIL-11-treated group at 6 hours. In conclusion, rhIL-11 decreased the severity of experimental pancreatitis early on but not later and inhibited the intrapancreatic TNF mRNA expression in vivo, suggesting that the protective effect of IL-11 during the early stage of acute pancreatitis may be mediated, at least in part, through modulation of TNF production.

Trypsin stimulates production of cytokines from peritoneal macrophages in vitro and in vivo

Acute pancreatitis (AP) is characterized by release of proteolytic enzymes from the pancreas and a powerful inflammatory cytokine cascade that mediates the systemic manifestations and contributes to the mortality of the disease. The purpose of this study was to examine a potential link between pancreatic proteolytic enzymes, which are increased in AP, and cytokine production. To evaluate this, we incubated rat peritoneal macrophages (PMO) with increasing concentrations of trypsin and measured cytokine production. Supernatants from the cell cultures were assayed for TNF-alpha and IL-1beta, and the PMO were collected for the evaluation of cytokine mRNA by polymerase chain reaction (PCR). Further to evaluate the role of pancreatic proteases in triggering the cytokine cascade in AP, trypsin was injected into the peritoneal cavity of Sprague-Dawley rats, and the production of cytokines was measured in the peritoneal fluid. Controls included injection of inactivated trypsin. Incubation of PMO with trypsin in vitro resulted in a dose-dependent increase in TNF-alpha production with maximal response (2,660.5+/-748.8 pg/mL) at 10 microg/mL protease. Peak TNF-alpha and IL-1beta release was noted 16 h after stimulation of the PMO (2,759.5+/-698.0 pg/mL and 160,596+/-4,065 cpm, respectively). Trypsin-induced TNF-alpha production was not due to release of cell-associated cytokine, inasmuch as activation of PMO with this protease causing an increase in TNF-alpha mRNA by 30 minutes, reaching a 14-fold increase at 4 h. Trypsin-injected animals produced TNF-alpha-containing ascitic fluid in a dose-dependent manner with peak TNF-alpha at 2 h (371.3+/-180 pg/mL) versus control (53.8+/-11.2 pg/mL; p < 0.022). No TNF-alpha was found in ascites of rats injected with heat-inactivated trypsin. Histologic examination of trypsin-injected animals revealed evidence of pulmonary inflammation at 2 and 4 hours. We conclude that the proteolytic enzyme trypsin stimulates cytokine production from macrophages in vitro and in vivo. This model demonstrates for the first time that trypsin is a potential mediator of the cytokine response seen during AP.

Clostridium difficile toxin: cytoskeletal changes and lactate dehydrogenase release in hepatocytes

BACKGROUND

We have found that Clostridium difficile toxins can evoke hepatocyte acute-phase protein synthesis, and that this effect is dependent on a functioning interleukin-1 (IL-1) receptor. The present study was undertaken to determine if C. difficile toxicity, as determined by actin rearrangement and lactate dehydrogenase (LDH) release, also requires a functioning IL-1 receptor.

METHODS

Primary hepatocyte cultures were prepared from normal mice, knockout mice deficient in the IL-1-converting enzyme (ICE), and knockout mice deficient in the IL-1 p80 receptor. Hepatocytes were treated for 24 h with C. difficile culture extract, purified C. difficile toxin A, or purified C. difficile toxin B. The actin cytoskeleton was examined using confocal microscopy, and LDH release was measured by spectrophotometric analysis.

RESULTS

C. difficile culture extract, toxin A, and toxin B induced collapse of the actin cytoskeleton in hepatocytes from normal mice. Hepatocytes from both the ICE-deficient mice and the IL-1 p80 receptor-deficient mice demonstrated similar responses to both toxins. These toxins also induced significant LDH release in a concentration-dependent fashion in the normal hepatocytes and the ICE-deficient hepatocytes. However, no significant increase in LDH release was observed in hepatocytes from IL-1 p80 receptor-deficient mice.

CONCLUSIONS

C. difficile toxins induce actin cytoskeletal collapse independent of IL-1 or the IL-1 receptor. In contrast, toxin-stimulated LDH release was dependent on the presence of the IL-1 receptor. Thus, separate pathways appear to mediate toxic effects as manifested by actin rearrangement and LDH release.

Quantitative measurement of P- and E-selectin adhesion molecules in acute pancreatitis: correlation with distant organ injury

OBJECTIVE

To determine whether expression of P- and E-selectin molecules is associated with the development of systemic organ manifestations in acute pancreatitis (AP).

SUMMARY BACKGROUND DATA

Overproduction of inflammatory cytokines in AP induces expression of adhesion molecules, which may lead to increased leukocytic infiltration and tissue damage. Understanding the temporal expression of these molecules could afford better measures for therapeutic intervention.

METHODS

Acute pancreatitis was induced in 30-day-old female C57/ bI/6J mice by feeding a choline-deficient/ethionine-supplemented diet (n = 95). Mice were divided into three groups. Group I (n = 35) was used to study the biochemical and histologic manifestations of AP and to evaluate the neutrophilic infiltration by myeloperoxidase activity and immunofluorescence. Groups II (n = 35) and III (n = 25) were used to evaluate expression of P- and E-selectin by the dual radiolabeled monoclonal antibody technique.

RESULTS

Biochemical and histologic evidence of AP developed in all mice. The inflammatory cytokine tumor necrosis factor-alpha gradually increased in serum as early as 18 hours, reaching more than 800-fold background levels by 72 hours. Biphasic P-selectin expression in the lung was seen with peaks at 24 and 48 hours; E-selectin expression peaked at 48 hours. CD18-positive leukocytes and increased myeloperoxidase activity in the lung were demonstrated at 24 hours, correlating with the onset of selectin upregulation. Histologic scoring of lung tissue demonstrated mild damage at 24 hours, with progressive injury occurring from 48 to 72 hours.

CONCLUSIONS

In AP, the production of inflammatory cytokines precedes up-regulation of P- and E-selectin, whose expression coincided with the increased infiltration of CD18-positive cells and neutrophil sequestration in lung tissue. Temporally, these events correlate with evidence of histologic pulmonary injury and underscore the role of adhesion molecules as mediators of pathophysiologic events. This mechanistic pathway may afford novel therapeutic interventions in clinical disease by using blocking agents to ameliorate the systemic manifestations of AP.

alpha2-macroglobulin- and murinoglobulin-1- deficient mice. A mouse model for acute pancreatitis

Mice deficient in either or both mouse alpha2-macroglobulin (MAM) and murinoglobulin-1 (MUG1) were generated and proved phenotypically normal under standard conditions. Acute pancreatitis was induced with a diet deficient in choline and methionine, supplemented with ethionine. The mortality was less than 25% in wild-type mice, as opposed to at least 56% in knockout mice, and was highest (70%) in MAM-/- mice, with earliest onset at 2 days. Plasma amylase and lipase levels were increased, but pancreatic tissue appeared histologically variable in individual mice. The clinical symptoms were most severe in MAM-/- mice and, surprisingly, were not aggravated in the double knockout mice, suggesting that the lack of proteinase inhibition capacity was not the major problem. Therefore, we analyzed the expression of 21 different cytokines and polypeptide factors in the pancreas of all experimental groups of mice. Interleukin-1-receptor antagonist mRNA was consistently induced by the diet in the pancreas of MAM-/- mice, and transforming growth factor-beta, tumor necrosis factor-alpha, tumor necrosis factor-beta, beta-lymphotoxin, and interferon-gamma mRNA levels were also increased. The data demonstrate the important role of alpha2-macroglobulin (A2M) in acute pancreatitis as both a proteinase inhibitor and a cytokine carrier. Mice deficient in MAM and/or MUG thus offer new experimental models for defining in vivo the role of the macroglobulins in pancreatitis and in other normal and pathological processes.

The potential role of therapeutic cytokine manipulation in acute pancreatitis

The central, detrimental role of the inflammatory cytokines IL-1 and TNF and the biologically active phospholipid PAF in the pathogenesis of AP has been established over the past 8 years. A number of antagonists to these mediators have been used successfully in the laboratory setting and are currently being examined in prospective randomized trials. The effectiveness of any antagonist depends not only on its ability to block the effects of the inflammatory mediators but also on its administration early enough in the course of the pancreatitis before pancreatic necrosis or organ dysfunction.