Soluble receptors released during acute pancreatitis interfere with the detection of tumor necrosis factor-alpha

Aggravation of acute pancreatitis by heparan sulfate in mice

OBJECTIVE

Systemic inflammatory response syndrome (SIRS) is responsible for pancreatitis-associated mortality, but its initiating events are poorly understood. Possible candidates may be endogenous substances, which have previously been shown to mediate inflammatory responses. The aim of this study was to investigate whether SIRS could be exaggerated by heparan sulfate (HS) in acute pancreatitis (AP).

MATERIAL AND METHODS

AP was induced in mice by cerulein injection and HS was administered one hour after the final cerulein injection. The severity of pancreatitis was assessed by serum amylase activity, pancreatic edema, and pancreatic myeloperoxidase (MPO) activity. Systemic inflammation was evaluated by assessing lung injury and by measuring serum levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6. Cytokine levels were also measured in pancreas and lung tissues.

RESULTS

HS did not worsen the pancreatic injury induced by cerulein. In contrast, HS exacerbated the systemic inflammation as measured by augmented lung MPO activity, increased lung TNF-alpha and IL-6 levels, and elevated serum IL-6 levels.

CONCLUSIONS

Our results indicate a potential role for HS in propagating pancreatic inflammation from a local process to a systemic response and thus suggest the possibility that blockade of HS might improve the outcome of SIRS in AP.

Randomized study of the effect of pentoxifylline or octreotide on serum levels of TNF-alpha and IL-6 after endoscopic retrograde cholangiopancreatography

OBJECTIVES

To study the effect of pentoxifylline and octreotide administration on serum levels of TNF-alpha and IL-6, in patients who underwent endoscopic retrograde cholangiopancreatography (ERCP), whether they developed pancreatitis or not.

METHODS

Out of 590 patients undergoing ERCP, 30 who developed pancreatitis and 25 who did not (controls) were enrolled. Pentoxifylline was given to 23 patients (15 with and eight without pancreatitis) and octreotide to 19 patients (nine with and 10 without pancreatitis, respectively). Thirteen patients did not receive any preventive medication (six with and seven without pancreatitis, respectively). Blood samples were collected at baseline, 6 and 24 h after ERCP.

RESULTS

IL-6 increased significantly in patients with pancreatitis at the 6 h (4.2 pg/ml SD: 5.8) and at the 24 h (6.6 pg/ml SD: 9.8) compared with patients without pancreatitis at the 6 h (2.1 pg/ml SD: 3.6) and 24 h (1.9 pg/ml SD: 2.5) (P < 0.01). No significant difference in the values of TNF-alpha and IL-6 obtained among the three study groups in patients with or without pancreatitis was observed. TNF-alpha levels at the 24 h were lower than baseline in patients with pancreatitis who received octreotide (P = 0.04).

CONCLUSION

IL-6 increased in the first 24 h of post-ERCP pancreatitis. Pentoxifylline and octreotide cannot prevent IL-6 elevation but octreotide reduces TNF-alpha levels, which may have an impact on the severity of post-ERCP pancreatitis.

Advances in the relationship between macrophage and acute pancreatitis

Acute pancreatitis (AP) has seriously endangered the life and health of human beings, and it is often accompanied with systemic inflammatory response syndrome (SIRS), serious infections, septic shock and multiple organ dysfunction syndrome, which lead to death of patients. With the deep study on the pathogenesis of AP mechanism, it is demonstrated that macrophages play an important role in antigen presentation-activated immune responses of AP patients. This paper reviews the progress in the relationship between macrophages and acute pancreatitis.

Role of tumor necrosis factor-alpha in acute pancreatitis: from biological basis to clinical evidence

Tumor necrosis factor (TNF)-alpha is a pleiotropic cytokine that exerts host-damaging effects in different autoimmune and inflammatory diseases. It is a key regulator of other proinflammatory cytokines and of leukocyte adhesion molecules, and it is a priming activator of immune cells. In recent years, several research lines-mostly derived from animal models and in vitro studies-suggested that TNF-alpha plays a pivotal role in the pathogenesis of acute pancreatitis. In particular, it contributes to the systemic progression of the inflammatory response and to the end-organ dysfunction often observed in severe disease. Current clinical applications of TNF-alpha in acute pancreatitis include the assessment of blood concentrations to predict disease severity and to identify individuals prone to develop complications such as multiple organ failure and septic shock. However, TNF-alpha is rapidly cleared from the bloodstream, and sensitivity and overall accuracy of its measurement seem strictly time dependent, thereby being of potential prognostic value only in the first days after the onset of the disease. In parallel, TNF-alpha has been evaluated as a novel pharmacologic target for treating pancreatitis. Although promising results have been observed in the laboratory, transition to clinical practice seems problematic, in particular, in the light of divergent results obtained in sepsis trials. Therefore, in future clinical trials pertaining to TNF-alpha neutralization in acute pancreatitis, timing of intervention should be related to changes in TNF-alpha serum levels, and inclusion and exclusion criteria should be accurately selected to better define the population most likely to benefit.

Importance of the liver in systemic complications associated with acute pancreatitis: the role of Kupffer cells

Although its exact nature is still unknown, acute pancreatitis progresses with a local production of inflammatory mediators, eventually leading to systemic inflammatory response syndrome. Knowing that almost all pancreatic mediators released from the pancreas to the bloodstream may pass through the liver before their dilution in the systemic circulation, it would be reasonable to assume a determinant role for this organ in the development of the inflammatory response associated with acute pancreatitis. Thus, recent studies have shown the involvement of the liver in the complex network of events triggering the multiorgan dysfunction associated with the disease. Once pancreatic mediators reach the liver, they strongly activate Kupffer cells, the resident macrophages, greatly amplifying the release of cytokines into the bloodstream and thus contributing to the systemic manifestations of acute pancreatitis. Altogether, these results show that the pancreas is not the only source of mediators that trigger the deleterious effects of acute pancreatitis, but that the liver may orchestrate the final outcome of the disease. The purpose of this review is to discuss progress in understanding the function of the liver in the early stages of the development of systemic organ dysfunction secondary to acute pancreatitis.

Influence of portal blood on the development of systemic inflammation associated with experimental acute pancreatitis

BACKGROUND

The liver is a source of systemic proinflammatory mediators in acute pancreatitis. We have investigated the effects of blood from the pancreas and intestine in liver activation and lung inflammation during early stages of experimental acute pancreatitis in a rat model.

METHODS

A portosystemic shunt and a mesosystemic shunt were created to prevent the passage of blood coming from the pancreas and the intestine, respectively, to the liver. Pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct. After 3 hours, the inflammatory process in the lung and intestine, plasma levels of tumor necrosis factor (TNF)-alpha and their soluble receptor, and mRNA expression of inflammatory mediators in the lung were evaluated.

RESULTS

Portocaval shunting of blood prevented the inflammatory process in the lung, an increase in plasma TNF-alpha concentration, and the expression of TNF-alpha, interleukin (IL)-1beta, and heat-shock protein (HSP)-72 in the lung, but had no effect on plasma levels of soluble TNF-alpha receptor or on expression of inducible nitric oxide synthase (iNOS) and macrophage inflammatory protein (MIP)-2 in the lung. In contrast, mesocaval shunting of blood did not modify any of the parameters evaluated.

CONCLUSIONS

Pancreatic blood, but not intestinal blood, plays a key role in liver activation during experimental acute pancreatitis.

Degradation and inactivation of plasma tumor necrosis factor-alpha by pancreatic proteases in experimental acute pancreatitis

BACKGROUND

Release of TNFalpha is thought to play an important role in mediating systemic effects in acute pancreatitis (AP). We have been unable to find an elevation of plasma TNFalpha in AP and hypothesize that it is susceptible to catabolism by circulating pancreatic proteases.

METHODS

(1) AP was induced in Sprague-Dawley rats by cerulein hyperstimulation preceded by intraductal infusion of saline (mild) or glycodeoxycholic acid (severe). Healthy and sham-operated animals served as controls. Severity of pancreatitis was confirmed by histology. Plasma TNFalpha levels were measured at various time points after induction of AP with competitive ELISA. (2) Recombinant rat TNFalpha (rrTNFalpha) was incubated with trypsin, elastase, chymotrypsin and pepsin. Western Blot was performed to visualize TNF degradation. (3) RrTNFalpha was incubated in a concentration and time-dependant manner with proteases and TNF bioactivity was evaluated with a cytotoxicity assay.

RESULTS

(1) Plasma TNFalpha levels in severe pancreatitis were significantly lower than in sham-operated controls after 0.5 and 6 h. (2) Incubation with proteases showed degradation in the presence of trypsin, elastase and chymotrypsin and no effect of pepsin. (3) There was a concentration dependent inactivation of rrTNFalpha in the presence of pancreatic proteases and a complete time-dependent inactivation in the presence of trypsin.

CONCLUSION

Plasma TNFalpha does not rise in experimental AP, and levels are significantly lower in severe pancreatitis compared to sham-operated controls. Our study demonstrates degradation and inactivation of TNFalpha by pancreatic proteases, suggesting that it is unlikely it plays an important role in the development of distant organ failure.

Role of macrophage inflammatory peptide-2 in cerulein-induced acute pancreatitis and pancreatitis-associated lung injury

Acute pancreatitis is an inflammatory process of variable severity, and leukocytes are thought to play a key role in the development of pancreatitis and pancreatitis-associated lung injury. The effects of mediators released by these inflammatory cells may induce tissue damage. The aim of our study was to evaluate the role of the chemokine, macrophage inflammatory protein-2 (MIP-2), in the pathogenesis of cerulein-induced pancreatitis and pancreatitis-associated lung injury. The severity of pancreatitis was measured by serum amylase, pancreatic edema, acinar cell necrosis, and myeloperoxidase activity. Lung injury was quantitated by evaluating lung microvascular permeability and lung myeloperoxidase activity. To determine the role of MIP-2 in the pathophysiology of the disease, anti-MIP-2 antibody was administered either 1 hour before or 2 hours after the start of cerulein administration. MIP-2 concentrations increased in serum, pancreas, and lung tissues in mice treated with cerulein. Anti-MIP-2 antibody administrated either before or after cerulein partially protected against pancreas and lung injury. These results show that MIP-2 plays a key role in the pathophysiology of acute pancreatitis and that MIP-2 blockade may improve the outcome of the disease.

Hereditary, familial, and idiopathic chronic pancreatitis are not associated with polymorphisms in the tumor necrosis factor alpha (TNF-alpha) promoter region or the TNF receptor 1 (TNFR1) gene

PURPOSE

Genetic alterations that are associated with acute and chronic pancreatitis remain to be identified.

METHODS

The authors investigated two functionally active tumor necrosis factor (TNF) promoter region polymorphisms at positions -238 and -308 and the entire coding region of the corresponding TNF receptor 1 (TNFR1) gene in 54 patients with hereditary, familial, and idiopathic chronic pancreatitis who were previously tested negative for cationic trypsinogen mutations by direct DNA sequencing.

RESULTS

In three patients, we detected novel DNA variants in the TNFR1 gene that did not segregate with the disease. The genotype frequencies of the TNF promoter polymorphisms were similar between patients and controls.

CONCLUSION

These polymorphisms are not associated with hereditary, familial, or idiopathic chronic pancreatitis.

Protective effect of melatonin and its precursor L-tryptophan on acute pancreatitis induced by caerulein overstimulation or ischemia/reperfusion

Melatonin, a pineal secretory product, synthesized from l-tryptophan, has received increased attention because of its antioxidative and immunomodulatory properties. It has been detected in the gut and shown to protect the gastric mucosa, and liver from acute damage, but the role of melatonin in the protection of the pancreas against acute inflammation is not clear. The aim of this study was to investigate the effects of melatonin and its precursor, l-tryptophan, on caerulein-induced pancreatitis (CIP) and on ischemia/reperfusion (I/R)-provoked pancreatitis in rats. CIP was induced by subcutaneous infusion of caerulein to the rats (25 microg/kg). I/R was induced by clamping of the inferior splenic artery for 30 min followed by 2 hr of reperfusion. Melatonin (10, 25 or 50 mg/hr) or l-tryptophan (50, 100 or 250 mg/kg) was given as a bolus intraperitoneal (i.p.) injection 30 min prior to the onset of pancreatitis. CIP and I/R were confirmed by histologic examination and manifested by typical pancreatic edema, by an increase of plasma levels of amylase (by 500% in CIP and by 40% in I/R) and the pro-inflammatory tumor necrosis factor alpha (TNFalpha) (by 500%). Lipid peroxidation products such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), were increased several fold in the pancreas CIP and I/R, whereas pancreatic blood flow (PBF) was significantly reduced in these animals. Pretreatment of rats subjected to CIP or to I/R with melatonin (25 or 50 mg/kg i.p.) or l-tryptophan (100 or 250 mg/kg i.p.) significantly reduced pancreatic edema, plasma levels of amylase and TNFalpha and diminished pancreatic MDA + 4-HNE contents, while enhancing PBF, pancreatic integrity and plasma levels of the anti-inflammatory interleukin 10 (IL-10). This was accompanied by a marked and dose-dependent rise of plasma melatonin immunoreactivity. Gene expression of N-acetyl transferase, an enzyme involved in melatonin biosynthesis, was detected in the pancreas of normal rats and was significantly enhanced in the rats with CIP. We conclude that exogenous melatonin, and that produced from l-tryptophan, attenuates pancreatic damage induced by CIP or by I/R and this effect may be attributable to the reduction in lipid peroxidation and TNFalpha release combined with an increase of plasma anti-inflammatory IL-10 in rats with acute pancreatitis.

Natural history of long-term lung injury in mouse experimental pancreatitis

OBJECTIVE

In patients suffering from acute pancreatitis, the pathogenesis of pancreatitis-associated lung injury is not completely understood. Several rodent models of pancreatitis-associated lung injury suggested that activated neutrophils and the release of proinflammatory mediators after the activation of inflammatory cells within the pancreas might play an important role in translating the pancreatic inflammation to the lungs. In this study, we examined the natural history of pancreatitis-associated lung injury during an entire week.

SUBJECTS

Mice were administered 12 hourly intraperitoneal injections of a supramaximal dose of cerulein.

MEASUREMENTS AND MAIN RESULTS

The severity of pancreatitis was time-dependent, with a maximal injury by 12-24 hrs after the start of cerulein administration. Pancreatitis was associated with a significant lung injury characterized by a rise in lung microvascular permeability, sequestration of neutrophils within the lungs, and a marked thickening of alveolar membranes. Within the lungs, the peak of macrophage inflammatory peptide-2, which attracts inflammatory cells within the injured area, preceded the peaks of both tumor necrosis factor-alpha and intercellular adhesion molecule-1. Moreover, histologic injury peaked by 12 hrs, with a full recovery at day 7. Serum macrophage inflammatory peptide-2 concentrations were significantly correlated with the occurrence of pulmonary leakage. Lung macrophage inflammatory peptide-2 concentrations peaked 12 hrs before pancreatic concentrations.

CONCLUSIONS

Mediators released by the pancreas into the blood during acute pancreatitis induce within the lungs the chronological expression of macrophage inflammatory peptide-2, tumor necrosis factor-alpha, and intercellular adhesion molecule-1.