Towards a novel treatment strategy for acute pancreatitis. 1. Reappraisal of the evidence on aetiogenesis

Role of methionine containing antioxidant combination in the management of pain in chronic pancreatitis: a systematic review and meta-analysis

BACKGROUND

Pain in CP results from inflammation and neuroimmune alterations that are associated with oxidative stress, among other mechanisms. This is marked by depletion of antioxidant defenses including methionine, which is a donor of methyl moieties that maintains the acinar transsulfuration pathway. We performed a systematic review and meta-analysis of trials evaluating methionine-containing antioxidants in CP.

PATIENT AND METHODS

Literature search was conducted in Medline/Pubmed, EMBASE, and Cochrane databases. Systematic review and meta-analysis was performed per PRISMA guidelines. Main study outcome was pain relief. GRADE system was used for quality assessment. Heterogeneity was assessed by the Q and I(2) measures; publication bias by Egger's test. Random-effect model (DerSimonian and Laird) was used if there was heterogeneity.

RESULTS

Eight studies (n = 411) were identified that used methionine-containing antioxidants. The study duration ranged from 10 wks to 12 months. All studies used methionine, organic selenium, ascorbate, beta-carotene and alpha-tocoferol. Four studies (including two RCTs) that reported change in pain scores were metaanalyzed. Though overall effect [standardized difference in means (95% CI)] on pain score reduction was -0.95 (-1.738 to -0.160) (z = -2.36; p = 0.018), the significance was lost when the two RCTs were meta-analyzed. RCTs that reported the number of pain free patients had a statistically significant overall effect of -3.204 (p = 0.001). Though more patients on methionine containing antioxidants had adverse events, majority of them were mild.

CONCLUSION

Methionine containing antioxidants appear to result in pain reduction in a significant proportion of CP patients. Further randomized controlled trials with homogeneous outcome measures are needed.

Increased expression of the intercellular adhesion molecule-1 (ICAM-1) on peripheral blood neutrophils in acute pancreatitis

PURPOSE

Considering the important role of neutrophils' activation in the pathogenesis of acute pancreatitis (AP), the aim of our study was to evaluate the expression of leukocytes' adhesion molecules in patients with AP.

PATIENTS/METHODS

Thirty-five patients (16 women and 19 men; age 32-77 years, median 56 years) with AP were prospectively included into our study. The absolute number of leukocytes was estimated by haematologic analyser. Surface neutrophils antigens (CD) were assayed by the direct fluorescence method for whole blood, using a flow cytometer.

RESULTS

At the day 1, significant increase of ICAM-1 expression was found in patients with severe AP (S-AP) (7280 mm(-3) vs 2850 mm(-3) in healthy control; p<0.05). In the days 2, 3 and 5 it sharply decreased and peaked again to 4860 mm(-3) at the day 10. In patients with mild AP (M-AP), not significant elevation of ICAM-1 quickly returned to normal level. In both forms of AP, neutrophil CD62L (L-selectin) expression reached the highest level at the day 1 (8800 mm(-3) and 9020 mm(-3), respectively in M-AP and S-AP, in comparison to 3400 mm(-3) in control; p<0.05). Expression of CD69 (neutrophils' marker of early activation) significantly increased in both M-AP and S-AP.

CONCLUSIONS

We have found an early and significant increase of peripheral blood neutrophil CD54/ICAM-1 expression, specific for S-AP but not for M-AP. It may provide a good marker predicting severe course of pancreatitis.

Unraveling the mystery of pain in chronic pancreatitis

Chronic pancreatitis is typically a painful condition and it can be associated with a severe burden of disease. The pathogenesis of pain in this disorder is poorly understood and its treatment has been largely empirical, often consisting of surgical or other invasive methods, with an outcome that is variable and frequently unsatisfactory. Human and experimental studies have indicated a critical role for neuronal mechanisms that result in peripheral and central sensitization. The pancreatic nociceptor seems to be significantly affected in this condition, with increased excitability associated with downregulation of potassium currents. Some of the specific molecules implicated in this process include the vanilloid receptor, TRPV1, nerve growth factor, the protease activated receptor 2 and a variety of others that are discussed in this Review. Studies have also indicated novel therapeutic targets for this condition.

Immune dysregulation in patients with severe acute pancreatitis

To investigate patients with severe acute pancreatitis (SAP) by dynamic levels of pro-/anti-inflammatory cytokines and endotoxin (ET) in plasma and the relationship between immunity and infection, organ dysfunction. Seventy-two patients with SAP were recruited. The ET, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-4 (IL-4) were determined on admission and days 3, 7, and 14. For comparison, patients were analyzed through infection group versus non-infection group, multiple organ dysfunction syndrome (MODS) group versus non-MODS group. There were sixteen patients with secondary infection, twenty-two with MODS, and nine deaths. The infection group had higher levels of ET than the non-infection group on days 3 and 7. The dynamic cytokine levels of patients in the MODS group were unanimous with those outcomes in the infection group. The levels of cytokines in the infection group were different from the non-infection group, with more levels of TNF-α, IL-6 on days 3 and 7 and less on days 14, and more levels of IL-10, IL-4 on days 7 and 14. The levels of TNF-α, IL-6 in the MODS group were different from the non-MODS group, with more levels on days 3 and 7, and less levels on days 14. Immune dysregulation may play an important role in infection and organ dysfunction for patients with SAP.

Chronic pancreatitis

Chronic pancreatitis is a progressive fibroinflammatory disease that exists in large-duct (often with intraductal calculi) or small-duct form. In many patients this disease results from a complex mix of environmental (eg, alcohol, cigarettes, and occupational chemicals) and genetic factors (eg, mutation in a trypsin-controlling gene or the cystic fibrosis transmembrane conductance regulator); a few patients have hereditary or autoimmune disease. Pain in the form of recurrent attacks of pancreatitis (representing paralysis of apical exocytosis in acinar cells) or constant and disabling pain is usually the main symptom. Management of the pain is mainly empirical, involving potent analgesics, duct drainage by endoscopic or surgical means, and partial or total pancreatectomy. However, steroids rapidly reduce symptoms in patients with autoimmune pancreatitis, and micronutrient therapy to correct electrophilic stress is emerging as a promising treatment in the other patients. Steatorrhoea, diabetes, local complications, and psychosocial issues associated with the disease are additional therapeutic challenges.

The combination of neurokinin-1 and galanin receptor antagonists ameliorates caerulein-induced acute pancreatitis in mice

Both galanin and substance P have been separately implicated in the pathogenesis of acute pancreatitis. We compared the efficacy of the combination of the galanin antagonist galantide and the neurokinin-1 receptor antagonist L703,606 with that of either alone in the treatment of acute pancreatitis. Acute pancreatitis was induced in mice with 7-hourly caerulein injections. Galantide was co-administered with each caerulein injection commencing with the first injection (prophylactic) or 2h after the first injection (therapeutic). L703,606 was administered either 30 min before (prophylactic), or 2h after the first caerulein injection (therapeutic). Combination of the two agents was also administered. Control groups received galantide, L703,606, or saline, without caerulein. Pancreata were harvested for histological examination and estimation of myeloperoxidase activity. Plasma amylase activity was measured. Prophylactic and therapeutic administration of galantide reduced the hyperamylasemia by 37% and 30% respectively whereas only prophylactic L703,606 reduced hyperamylasemia (by 34%). Prophylactic administration of the combined antagonists reduced the hyperamylasemia by 44%. In contrast, therapeutic administration of the combination significantly increased plasma amylase levels by 27%. The plasma amylase activity in the control groups was similar to basal levels. Prophylactic and therapeutic administration of either antagonist or the combination significantly reduced myeloperoxidase activity. Galantide and L703,606 individually, and in combination, significantly reduced the acute pancreatitis-induced necrosis score. The administration of the combined antagonists does not offer any further benefit as compared to galantide alone. An interaction between neurokinin-1 and galanin receptors may occur to modulate amylase secretion.

Cathepsin B activates human trypsinogen 1 but not proelastase 2 or procarboxypeptidase B

BACKGROUND/AIMS

Activation of trypsinogen to trypsin is a crucial step in the development of acute pancreatitis. The cause of this activation is not known although suggested explanations include autoactivation, cathepsin B-mediated activation and activation by mast cell tryptase. The aim of this study was to investigate cathepsin B and tryptase activation of pancreatic zymogens.

METHODS

Trypsinogen-1, proelastase, and procarboxypeptidase B were purified from human pancreatic juice. Human cathepsin B and betaI-tryptase are commercial products. Activation and degradation of zymogens were measured by activity towards specific substrates for trypsin and pancreatic elastase, ELISAs for procarboxypeptidase B and its activation peptide, and a radioimmunoassay for the trypsinogen activation peptide.

RESULTS

Cathepsin B caused activation of trypsinogen-1 with a trypsin yield of about 30% of that produced by enterokinase. Proelastase and procarboxypeptidase B was not activated by cathepsin B. None of the zymogens were inactivated by cathepsin B. Neither monomeric nor tetrameric tryptase could activate any of the examined zymogens.

CONCLUSION

Cathepsin B is a competent activator of trypsinogen-1, although not as efficient as enterokinase. If cathepsin B is to play a role in protease activation in acute pancreatitis, this most probably occurs by activation of trypsinogen.

Intravenous antioxidant modulation of end-organ damage in L-arginine-induced experimental acute pancreatitis

BACKGROUND

Oxidative stress mediates acinar injury in experimental acute pancreatitis (AP) and antioxidants are depleted in human AP. This study tests the hypothesis that exogenous antioxidant supplementation ameliorates experimental AP.

METHODS

Male Sprague-Dawley rats were randomly allocated to 1 of 4 groups (n = 5/group) and sacrificed at 72 h. AP was induced by 250 mg per 100 g body weight of 20% L-arginine hydrochloride in 0.15 mol/l sodium chloride. Group allocations were: group 1 (control) no intervention; group 2 AP; group 3 early multiple antioxidant (MAOX) intervention comprising 15 microg/kg selenium, 30 microg/kg ascorbate and 300 mg/kg N-acetylcysteine given at 6 and 30 h and group 4 the MAOX combination above given at 24 and 48 h. Endpoints were: serum amylase, antioxidant levels, bronchoalveolar lavage (BAL) protein and lung myeloperoxidase (MPO) activity and histological assessment of pancreatic injury.

RESULTS

L-arginine induced AP characterised by oedema, neutrophil infiltration, acinar cell degranulation and elevated serum amylase. Early MAOX reduced pulmonary MPO and BAL protein and reduced acinar swelling, degranulation and pancreatic parenchymal infiltration by inflammatory cells. These features were absent when intervention was delayed.

CONCLUSION

In this model, early but not late antioxidant intervention ameliorates pancreatic and pulmonary injury.

Dynamics of antioxidants in patients with acute pancreatitis and in patients operated for colorectal cancer: a clinical study

OBJECTIVES

This clinical study compared the dynamics of antioxidants levels in patients with acute pancreatitis (AP), patients operated for colorectal cancer (CA), and healthy control subjects.

METHODS

This prospective descriptive study enrolled 21 AP and 14 CA patients and 17 healthy controls. Blood was collected from AP patients on days 1, 5, and 9 and from CA patients before surgery and on days 1, 5, and 9 after surgery. We measured concentrations of selenium in plasma, red blood cells (RBCs), and big-toe nails, vitamin A (retinol) in serum, alpha-tocopherol in serum and in RBCs, vitamin C in serum, concentration ratio of 9,11- and 10,12-octadecanoic acids to linoleic acid in RBC membrane, activity of superoxide dismutase, and glutathione peroxidase in RBCs.

RESULTS

Plasma concentrations of selenium, vitamin A, and vitamin C were significantly lower in AP and CA patients than in healthy controls over the monitored period (P < 0.05). Patients with severe AP had a significantly lower concentration of selenium in RBCs than did healthy controls and CA patients (P < 0.05). The concentration of selenium in toe nails of AP patients was significantly lower than that in CA patients and healthy controls (P < 0.001). The marker of increased reactive oxygen species activity the ratio of 9,11- and 10,12-octadecanoic acids to linoleic acid in RBCs was significantly higher in AP and CA patients than in healthy controls (P < 0.05).

CONCLUSIONS

Low levels of measured antioxidants and increased activity of reactive oxygen species occurred during the course of AP. These findings applied in particular to patients who had severe AP. Levels of measured antioxidants seemed to be similar in AP and CA patients except for lower levels of selenium in toe nails in AP patients and lower selenium concentrations in RBCs in patients with severe AP.

Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

BACKGROUND

Experimental studies have demonstrated that protein and lipid oxidation is a feature of acute pancreatitis and that antioxidant pretreatment can ameliorate the severity of the disease. Justification for a clinical trial of antioxidant therapy requires stronger evidence for oxidative stress in patients.

AIMS

To determine if oxidative stress is evident in patients with acute pancreatitis on admission to hospital, if it increases after admission and if it is related to disease severity.

METHODS

Measurement of plasma concentrations of protein carbonyls and malondialdehyde as markers of protein oxidation and lipid peroxidation, respectively, in a consecutive series of 85 patients with acute pancreatitis 0, 2 and 5 days after admission.

RESULTS

Patients with acute pancreatitis had significantly increased concentrations of protein carbonyls in plasma on recruitment (median 27 h after the onset of symptoms) that persisted over 5 days. Protein carbonyls were higher in severe compared with mild disease (median 0.099 and 0.043 nmol/mg protein, respectively, p = 0.0016). They were higher at day 0 in patients recruited with more established pancreatitis than in those presenting early. No increases in malondialdehyde were seen. Receiver operator characteristic curve analysis demonstrated that protein carbonyls at day 0 were comparable with C-reactive protein at predicting pancreatitis severity.

CONCLUSION

Our demonstration of substantial protein oxidation provides further evidence for oxidative stress in patients with severe pancreatitis. Our results suggest that there could be a window for early antioxidant intervention and that protein carbonyls could be a useful plasma marker of oxidative injury.

UDP glucuronosyltransferase (UGT1A7) gene polymorphisms increase the risk of chronic pancreatitis and pancreatic cancer

BACKGROUND & AIMS

Chronic pancreatitis and pancreatic adenocarcinoma are associated with alcohol abuse, consumption of tobacco smoke, and environmental aromatic hydrocarbon exposure. The role of genetic factors is incompletely defined. Uridine 5'-diphosphate glucuronosyltransferases are phase II detoxifying enzymes capable of tobacco-borne toxicant inactivation and cellular protection. This study analyzes UGT1A7 gene polymorphisms in pancreatic diseases.

METHODS

Genomic DNA from northern German white patients with pancreatic adenocarcinoma (n = 52) and chronic pancreatitis (n = 146), as well as healthy blood donors (n = 235) was analyzed by UGT1A7-specific PCR, sequencing analysis, and temperature gradient gel electrophoresis. Pancreatic expression of UGT1A genes was identified by duplex reverse-transcription PCR.

RESULTS

Predominant expression of the UGT1A7 gene was identified in human pancreatic tissue. Pancreatic adenocarcinoma was associated with the low detoxification activity UGT1A7*3 allele, which combines the W208R, N129K, and R131K mutations (odds ratio [OR], 1.98; 95% confidence interval [CI ], 1.24-3.14; P = 0.003). The association of UGT1A7*3 was especially strong in smokers with pancreatic carcinoma who were younger than 55 years (OR, 4.7; 95% CI, 1.9-11.8; P = 0.0009). Chronic pancreatitis was also associated with UGT1A7*3 (OR, 1.76; 95% CI, 1.26-2.46; P = 0.0009). UGT1A7*3 was specifically associated with the subgroup of patients with alcoholic pancreatitis, of whom 89% were smokers (OR, 2.24; 95% CI, 1.46-3.43; P = 0.0001) but was not associated with the nonalcoholic pancreatitis subgroup.

CONCLUSIONS

The UGT1A7 gene is predominantly expressed in human pancreas. The low detoxification activity UGT1A7*3 allele is identified as a novel risk factor of pancreatic diseases defining the interaction of genetic predisposition and environmentally induced oxidative injury.

Towards a novel treatment strategy for acute pancreatitis. 2. Principles and potential practice

In part 1 it was argued that a 'free radical-mast cell' template for the aetiogenesis of acute pancreatitis accommodates the evidence, whereas the prevailing 'trypsin-cytokine' template does not. In this sequel I examine the ramifications of the new philosophy in relation to speedier diagnosis, prognostic aids and, above all, a programme of active treatment which - once validated in experimental studies - could be implemented by the first medical respondent.