GPER-mediated, oestrogen-dependent visceral hypersensitivity in stressed rats is associated with mast cell tryptase and histamine expression.

Visceral hypersensitivity (VH) is common in irritable bowel syndrome (IBS), and female patients are more likely to seek healthcare services for IBS-related abdominal pain. Oestrogen has been reported to mediate pain modulation via its receptor, and mast cells are known to participate in the development of visceral hypersensitivity. Our previous studies showed that the G-protein-coupled oestrogen receptor (GPER, also known as GPR30) was expressed by mast cells in human colonic tissues and was associated with IBS type and severity of visceral pain. However, whether GPER is involved in oestrogen-dependent visceral hypersensitivity via mast cell degranulation is still unknown. Rats were subjected to wrap partial restraint stress to induce visceral hypersensitivity and were ovariectomized (OVX) to eliminate the effects of oestrogen on visceral hypersensitivity. OVX rats were treated with oestrogen, an oestrogen receptor α and ß antagonist (ICI 182.780), a GPER antagonist (G15) or a GPER agonist (G1), to evaluate the effects of oestrogen via its receptor. The colorectal distention test was performed to assess visceral sensitivity. Immunofluorescence studies were performed to evaluate GPER and mast cell tryptase co-expression. Mast cell number with degranulation was detected by specific staining. Mast cell tryptase expression in rat colon was also investigated by Western blot and immunohistochemistry. Substance P and histamine expression were examined by ELISA. GPER was expressed by the majority of tryptase-positive mast cells in the colonic mucosa. Stressed rats showed increased visceral sensitivity, increased mast cell degranulation, mast cell tryptase expression, and increased colon histamine levels. Ovariectomy reduced stress-induced VH in female rats and decreased mast cell degranulation, mast cell tryptase expression, and histamine levels, whereas oestrogen replacement reversed these effects. In OVX rats, the GPER antagonist G15 counteracted the enhancing effects of oestrogen on stress-induced VH, mast cell degranulation, mast cell tryptase, and histamine expression, whereas VH was preserved after treatment with ICI 182.780. On the other hand, pretreatment with the selective GPER agonist G1 at doses between 1 and 20 µg/kg significantly increased VH, mast cell tryptase, and histamine expression in OVX-stressed rats, mimicking the effects of oestrogen. GPER plays a pivotal role in the regulation of mast cell degranulation, mast cell tryptase expression, and histamine levels and contributes to the development of colonic hypersensitivity in a female rat model of IBS.

Visceral hypersensitivity in inflammatory bowel diseases and irritable bowel syndrome: The role of proteases.

Proteases, enzymes catalyzing the hydrolysis of peptide bonds, are present at high concentrations in the gastrointestinal tract. Besides their well-known role in the digestive process, they also function as signaling molecules through the activation of protease-activated receptors (PARs). Based on their chemical mechanism for catalysis, proteases can be classified into several classes: serine, cysteine, aspartic, metallo- and threonine proteases represent the mammalian protease families. In particular, the class of serine proteases will play a significant role in this review. In the last decades, proteases have been suggested to play a key role in the pathogenesis of visceral hypersensitivity, which is a major factor contributing to abdominal pain in patients with inflammatory bowel diseases and/or irritable bowel syndrome. So far, only a few preclinical animal studies have investigated the effect of protease inhibitors specifically on visceral sensitivity while their effect on inflammation is described in more detail. In our accompanying review we describe their effect on gastrointestinal permeability. On account of their promising results in the field of visceral hypersensitivity, further research is warranted. The aim of this review is to give an overview on the concept of visceral hypersensitivity as well as on the physiological and pathophysiological functions of proteases herein.

Lactase persistence versus lactose intolerance: Is there an intermediate phenotype?

BACKGROUND: According to the prevailing theory about the genetic background to lactose intolerance, there are three genotypes but only two adult physiological phenotypes: lactase persistence in individuals with the CT and TT genotypes and lactase non-persistence in individuals with the CC genotype. However, analysis of lactase activity from intestinal biopsies has revealed three distinct levels of activity, suggesting that an intermediate physiological phenotype may exist. AIM: To assess possible disparities between different genotypes with regard to biomarkers of lactase activity and physical symptoms during an oral lactose load test. METHODS: A retrospective study using an oral lactose load test (n=487). Concentrations of hydrogen in exhaled air and blood glucose were measured. Afterwards, subjects were asked to provide oral mucosa samples for genotyping and answer a questionnaire (participation rate 56%, n=274). RESULTS: Mean hydrogen levels in exhaled air at 120min were significantly higher in the CT genotype than in the TT genotype. There was no significant difference in blood glucose levels between the two groups. Reported symptoms, with the possible exception of abdominal pain, were equally prevalent in both groups. CONCLUSIONS: Subjects with the CT and TT genotypes, hitherto classified as lactase-persistent, differ in their physiological response to lactose intake, indicating differences in phenotype which could have clinical significance.

Pain in the Early Phase of Pediatric Pancreatitis (PINEAPPLE Trial): Pre-Study Protocol of a Multinational Prospective Clinical Trial.

BACKGROUND: There are unexpectedly large differences between the incidences of acute pancreatitis (AP) as indicated by different hospitals. Retrospective studies suggest that the reason behind this is the large differences that exist between the local managements of abdominal pain at emergency units. Unfortunately, no evidence-based medicine (EBM) guidelines are available to give proper instruction concerning the necessity of serum pancreatic enzyme measurement during abdominal pain. SUMMARY: Pain in Early Phase of Pediatric Pancreatitis (PINEAPPLE) is an observational, multinational observational clinical trial to explore the route from the first sign of abdominal pain to the diagnosis of pancreatitis (PINEAPPLE trial). The PINEAPPLE-R subtrial is a retrospective review on the records of children (patients under 18) appearing at emergency units - a review of their clinical symptoms, results of imaging examinations and laboratory parameters. The PINEAPPLE-P subtrial is a prospective trial designed to develop a fast and simple EBM guideline that helps to evaluate (in a reliable and cost-efficient way) the necessity of pancreatic enzyme test and abdominal ultrasonography (or even computed tomography) when a child has abdominal pain. The trial has been registered at the ISRCTN registry and has received the relevant ethical approval. KEY MESSAGE: The PINEAPPLE trial will help to recognize AP in children in a highly efficient manner.

Inducible Nitric Oxide Synthase in the Duodenal Mucosa Is Associated with Mast Cell Degranulation in Patients with Functional Dyspepsia.

AIM: Functional dyspepsia (FD) is a clinical syndrome with chronic gastroduodenal symptoms without noticeable organic or systemic diseases. According to the Rome III consensus, FD can be subdivided into PDS (postprandial distress syndrome) and EPS (epigastric pain syndrome). Neurotransmitters are involved in the development and pathology of FD. However, the expression profiles of neurotransmitters in FD patients are not clear. This study aimed to investigate the expression profile of neurotransmitters in the duodenal mucosa of FD patients. METHODS: A total of 48 FD patients treated at our hospital were included in this study: 23 patients with PDS and 25 patients with EPS. Another 21 healthy volunteers served as normal controls. The duodenal mucosa was biopsied with gastroscopy and examined with immunohistochemical staining against serotonin, substance P, inducible nitric oxide synthase (iNOS), and vasoactive intestinal peptide (VIP). Mast cells were identified with toluidine blue staining. RESULTS: The duodenal iNOS levels were significantly higher in PDS patients than the normal controls (P<0.05). The expression of serotonin, substance P, and VIP did not differ significantly among the groups. Mast cell counts and the percentage of mast cells with degranulation were significantly higher in PDS and EPS patients than normal controls (P<0.001) In addition, iNOS expression levels were positively correlated with percentage of degranulating mast cells (r=0.321, P=0.008). CONCLUSIONS: In conclusion, duodenal iNOS may be involved in the pathogenesis of PDS.

Milk Intolerance, Beta-Casein and Lactose.

True lactose intolerance (symptoms stemming from lactose malabsorption) is less common than is widely perceived, and should be viewed as just one potential cause of cows' milk intolerance. There is increasing evidence that A1 beta-casein, a protein produced by a major proportion of European-origin cattle but not purebred Asian or African cattle, is also associated with cows' milk intolerance. In humans, digestion of bovine A1 beta-casein, but not the alternative A2 beta-casein, releases beta-casomorphin-7, which activates µ-opioid receptors expressed throughout the gastrointestinal tract and body. Studies in rodents show that milk containing A1 beta-casein significantly increases gastrointestinal transit time, production of dipeptidyl peptidase-4 and the inflammatory marker myeloperoxidase compared with milk containing A2 beta-casein. Co-administration of the opioid receptor antagonist naloxone blocks the myeloperoxidase and gastrointestinal motility effects, indicating opioid signaling pathway involvement. In humans, a double-blind, randomized cross-over study showed that participants consuming A1 beta-casein type cows' milk experienced statistically significantly higher Bristol stool values compared with those receiving A2 beta-casein milk. Additionally, a statistically significant positive association between abdominal pain and stool consistency was observed when participants consumed the A1 but not the A2 diet. Further studies of the role of A1 beta-casein in milk intolerance are needed.

Luminal cysteine-proteases degrade colonic tight junction structure and are responsible for abdominal pain in constipation-predominant IBS.

OBJECTIVES: Luminal serine-proteases lead to increased colonic paracellular permeability and visceral hypersensitivity in patients with diarrhea-predominant irritable bowel syndrome (IBS-D). Other proteases, namely cysteine-proteases (CPs), increase airway permeability by digesting epithelial tight junction proteins. In this study, we focused on constipation-predominant IBS (IBS-C) and we aimed to (i) evaluate CP levels in two cohorts of IBS patients, (ii) test if IBS-C fecal supernatant (FSN) affects permeability, and visceral sensitivity after repeated administrations in mice, and (iii) evaluate occludin expression in IBS-C colonic biopsies. METHODS: Fecal CP activity was determined using selective substrate and inhibitor (E64). The effect of papain, as positive control, and IBS-C FSN administrations were evaluated on colonic paracellular permeability and mucosal occludin levels in mice and T84 monolayers. Occludin protein levels were evaluated in IBS-C colonic biopsies. Sensitivity to colorectal distension (CRD) was measured after repeated administrations of IBS-C FSN. RESULTS: We found in a subset of IBS-C patients an enhanced fecal CP activity, in comparison with healthy controls and IBS-D patients. CP activity levels positively correlated with disease severity and abdominal pain scoring. This association was confirmed by receiver operating characteristic curve analysis. In mice, repeated application of IBS-C FSN into colon triggered increased permeability, linked to the enzymatic degradation of occludin, and was associated with enhanced visceral sensitivity to CRD. Finally, occludin levels were found decreased in colonic biopsies from IBS-C patients, and IBS-C FSNs were able to degrade recombinant human occludin in vitro. All these effects were abolished by preincubation of IBS-C FSN with a CP inhibitor, E64. CONCLUSIONS: These data suggest that luminal CPs may represent a new factor contributing to the genesis of symptoms in IBS.

Anti-inflammatory effect of (E)-4-(3,7-dimethylocta-2,6-dienylamino)phenol, a new derivative of 4-nerolidylcatechol.

OBJECTIVES: We have investigated the anti-inflammatory and antinociceptive effects of (E)-4-(3,7-dimethylocta-2,6-dienylamino)phenol (LQFM-015), which was designed through molecular simplification strategy from 4-nerolidylcatechol. METHODS: The possible anti-inflammatory and antinociceptive effects were assayed on carrageenan-induced paw oedema and pleurisy, acetic acid-induced abdominal writhing and formalin tests in mice. KEY FINDINGS: LQFM-015 reduced the activity of PLA2 enzyme in vitro by 18%. Docking studies into the catalytic site of PLA2 were used to identify the binding mode of the LQFM-015. LQFM-015 showed a moderate antinociceptive effect, since this compound reduced the number of writhings by approximately up to 40% in the acetic acid-induced pain model; this antinociceptive activity also emerged in the second phase of the formalin-induced pain model (58% of inhibition). The anti-inflammatory action of LQFM-015 was confirmed in acute inflammation models, in which it reduced the formation of oedema to 52.78 ± 8.6 and 46.64 ± 5.2 at the second and third hour of carrageenan-induced paw oedema, respectively. Also in the carrageenan-induced pleurisy model, LQFM-015 reduced the migration of leucocytes by 26.0% and decrease myeloperoxidase activity by 50%. LQFM-015 showed different concentrations to inhibit 50% of isoenzyme cyclooxygenase activity (IC50); COX-1 IC50 = 36 µM) and COX-2 IC50 = 28 µM. CONCLUSIONS: LQFM-015 demonstrated inhibition of both PLA2 and COX enzymes; thus, the moderate antinociceptive effect of this compound could be attributed to its anti-inflammatory activity.

Examination of serum pepsinogen in functional dyspepsia.

BACKGROUND/AIMS: Although serum pepsinogen (PG) is considered as a marker of gastric atrophy, it also reflects gastric acid secretion, which closely influences dyspeptic symptoms. We investigated serum PG levels and PGI/PGII ratios in dyspeptic patients, in relation to various different subtypes of symptoms including Rome III classifications. METHODOLOGY: Serum PGs were measured in 75 subjects with dyspeptic symptoms and 42 asymptomatic healthy subjects. RESULTS: PG II level was significantly higher (p=0.0001) and PG I/II ratio was significantly lower (p<0.0001) in subjects with H. pylori infection than those without, while no associations were found between PG levels and usage of H2 receptor antagonists or proton-pump inhibitors. In all subjects with pain in stomach, abdominal bloating and PDS-like symptoms according to Rome III criteria, presented significantly higher levels of PGI, compared to subjects without symptoms (p=0.043, 0.015 and 0.037, respectively). In addition, burning sensation and abdominal pain presented significantly higher PGI/II ratios (p=0.0005 and 0.003, respectively), and higher PGI/II ratio was also positively correlated with a number of symptoms (p=0.04). When subjects were divided according to H. pylori infection status, higher PGI/II ratio was significantly associated with abdominal pain in H. pylori negative subjects (p=0.03), while higher PGI level was significantly associated with functional esophageal disorders (FEG) according to Rome III criteria, and higher number of dyspeptic symptoms in H. pylori positive subjects (p=0.016). CONCLUSIONS: Our data suggest that subjects with higher PGI level, and PG I/II ratio are more likely to develop several dyspeptic symptoms.

Chelating luminal zinc mimics hydrogen sulfide-evoked colonic pain in mice: possible involvement of T-type calcium channels.

Luminal hydrogen sulfide (H(2)S) causes colonic pain and referred hyperalgesia in mice through activation of T-type Ca(2+) channels. To test a hypothesis that H(2)S might chelate and remove endogenous Zn(2+) that inhibits the Ca(v)3.2 isoform of T-type Ca(2+) channels, facilitating visceral nociception, we asked if intracolonic (i.col.) administration of Zn(2+) chelators mimics H(2)S-induced visceral nociception. Visceral nociceptive behavior and referred abdominal allodynia/hyperalgesia were determined after i.col. administration of NaHS, a donor for H(2)S, or Zn(2+) chelators in mice. Phospholylation of extracellular signal-regulated protein kinase (ERK) in the spinal cord was analyzed by immunohistochemistry. The visceral nociceptive behavior and referred abdominal allodynia/hyperalgesia caused by i.col. NaHS in mice were abolished by i.col. preadministration of zinc chloride (ZnCl(2)), known to selectively inhibit Ca(v)3.2, but not Ca(v)3.1 or Ca(v)3.3, isoforms of T-type Ca(2+) channels, and by i.p. preadministration of mibefradil, a pan-T-type Ca(2+) channel blocker. Two distinct Zn(2+) chelators, N,N,N',N'-tetrakis(2-pyridylmethyl)ehylenediamine (TPEN) and dipicolinic acid, when administered i.col., mimicked the NaHS-evoked visceral nociceptive behavior and referred abdominal allodynia/hyperalgesia, which were inhibited by mibefradil and by NNC 55-0396, another T-type Ca(2+) channel blocker. Like i.col. NaHS, i.col. TPEN caused prompt phosphorylation of ERK in the spinal dorsal horn, an effect blocked by mibefradil. Removal of luminal Zn(2+) by H(2)S and other Zn(2+) chelators thus produces colonic pain through activation of T-type Ca(2+) channels, most probably of the Ca(v)3.2 isoform. Hence, endogenous Zn(2+) is considered to play a critical role in modulating visceral pain.

Serine proteases mediate inflammatory pain in acute pancreatitis.

Acute pancreatitis is a life-threatening inflammatory disease characterized by abdominal pain of unknown etiology. Trypsin, a key mediator of pancreatitis, causes inflammation and pain by activating protease-activated receptor 2 (PAR(2)), but the isoforms of trypsin that cause pancreatitis and pancreatic pain are unknown. We hypothesized that human trypsin IV and rat P23, which activate PAR(2) and are resistant to pancreatic trypsin inhibitors, contribute to pancreatic inflammation and pain. Injections of a subinflammatory dose of exogenous trypsin increased c-Fos immunoreactivity, indicative of spinal nociceptive activation, but did not cause inflammation, as assessed by measuring serum amylase and myeloperoxidase activity and by histology. The same dose of trypsin IV and P23 increased some inflammatory end points and caused a more robust effect on nociception, which was blocked by melagatran, a trypsin inhibitor that also inhibits polypeptide-resistant trypsin isoforms. To determine the contribution of endogenous activation of trypsin and its minor isoforms, recombinant enterokinase (ENK), which activates trypsins in the duodenum, was administered into the pancreas. Intraductal ENK caused nociception and inflammation that were diminished by polypeptide inhibitors, including soybean trypsin inhibitor and a specific trypsin inhibitor (type I-P), and by melagatran. Finally, the secretagogue cerulein induced pancreatic nociceptive activation and nocifensive behavior that were reversed by melagatran. Thus trypsin and its minor isoforms mediate pancreatic pain and inflammation. In particular, the inhibitor-resistant isoforms trypsin IV and P23 may be important in mediating prolonged pancreatic inflammatory pain in pancreatitis. Our results suggest that inhibitors of these isoforms could be novel therapies for pancreatitis pain.

The effect of oral supplementation with Lactobacillus reuteri or tilactase in lactose intolerant patients: randomized trial.

BACKGROUND: Lactase enzyme supplements and probiotics with high beta-galactosidase activity may be valid treatment options for the lactose intolerance. Aim of this study was to assess whether supplementation with tilactase or Lactobacillus reuteri when compared to placebo affects hydrogen breath excretion and gastrointestinal symptoms in lactose intolerant patients during lactose breath test (H,-LBT). METHODS: Sixty lactose intolerant patients participated in the study and were randomized to three 20 patients-treatment groups: tilactase group (tilactase 15 minutes before control H2-LBT); placebo group (placebo 15 minutes before control H2-LBT); Lactobacillus reuteri group (LR) (LR b.i.d. during 10 days before control H2-LBT). The outcomes were LBT normalization rate, and influences of treatments on both mean maximum hydrogen concentration and clinical score. RESULTS: LBT normalization rate was significantly higher in tilactase and LR groups with respect to placebo. Tilactase was significantly more effective than LR in achieving LBT normalization (p <0.01). Both significant reduction of mean peak H2 excretion and improvement of the mean clinical score were observed in tilactase and LR groups after treatment with respect to placebo (p <0.0001). Tilactase was significantly more effective than LR in reducing both mean peak hydrogen excretion and mean clinical score. CONCLUSIONS: In lactose intolerants, tilactase strongly improves both LBT results and gastrointestinal symptoms after lactose ingestion with respect to placebo. Lactobacillus reuteri also is effective but lesser than tilactase. This probiotic may represent an interesting treatment option for lactose intolerance since its use is simple and its effect may last in the time after stopping administration.

Matrix metalloproteinase levels in acute aortic dissection, acute pancreatitis and other abdominal pain.

BACKGROUND: Acute aortic dissection (AAD) is a life-threatening emergency. Patients with AAD who have abdominal pain are easily confused with patients with surgical acute abdomen. Matrix metalloproteinases (MMPs) play an important role in the pathophysiology of AAD. This study was undertaken to compare serum MMP-9 levels in patients with acute abdomen and those with AAD presenting as abdominal pain in the emergency department. METHODS: Blood samples were collected within 1 h and 24 h after admission to the emergency department. Serum levels of MMP-9, lipoprotein (a) (LP(a)) and high-sensitivity C-reactive protein (hsCRP) were measured in 20 healthy controls, 20 patients with acute pancreatitis, 20 with other acute abdomen and 20 patients with AAD with abdominal pain by enzyme-linked immunosorbent assay and immunoturbidimetric assay, respectively. RESULTS: Serum MMP-9, LP(a) and hsCRP levels were significantly higher in the three groups of patients than in the healthy controls, with no significant fluctuation within 24 h of admission in any group. Mean serum MMP-9 levels in patients with acute pancreatitis (768 (95% CI 651 to 885) ng/ml within 1 h; 708 (95% CI 677 to 740) ng/ml at 24 h) were significantly higher than in patients with other acute abdomen (244 (95% CI 182 to 266) ng/ml within 1 h; 259 (95% CI 219 to 299) ng/ml at 24 h) and lower than in patients with AAD (1052 (95% CI 921 to 1183) ng/ml at 1 h; 1107 (95% CI 973 to 1241) ng/ml at 24 h) (all p<0.05). No significant difference was detected in serum LP(a) and hsCRP levels among the three groups of patients. CONCLUSIONS: Patients with AAD who have abdominal pain have significantly higher serum MMP-9 levels than patients with surgical acute abdomen.

Acute hemorrhagic edema of infancy with abdominal pain and elevated transaminases.

Acute hemorrhagic edema of infancy is a rare type of leukocytoclastic vasculitis characterized by a triad of fever, edema, and rosette-shaped purpura, mainly over the face, auricles, and extremities in a nontoxic infant. Visceral involvement is infrequent in acute hemorrhagic edema of infancy. We report a case of acute hemorrhagic edema of infancy with abnormal liver function tests and abdominal pain.

Activation of extracellular signal-regulated protein kinase in sensory neurons after noxious gastric distention and its involvement in acute visceral pain in rats.

BACKGROUND & AIMS: Changes in the properties of visceral sensory neurons contribute to the development of gastrointestinal pain. However, little is known about the molecules involved in mechanosensation from the gastrointestinal tract. We investigated the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), a member of the mitogen-activated protein kinase cascade, in dorsal root ganglion (DRG) and nodose ganglion (NG) neurons by noxious gastric distention (GD) and its involvement in acute visceral pain in rats. METHODS: Electromyographic responses to gastric balloon distention through gastrostomy were recorded from the acromiotrapezius muscle in rats after splanchnic nerve resection or vagotomy and in control rats. We then examined the phosphorylated-ERK1/2 (p-ERK1/2) labeling in the DRG and NG after GD using immunohistochemistry. RESULTS: Gastric distention induced p-ERK1/2 in DRG and NG neurons with a peak at 2 minutes after stimulation. We found a stimulus intensity-dependent increase in the number of activated neurons, and this activation corresponded well with the incidence of the visceromotor response. Most of these p-ERK1/2-labeled neurons were small- and medium-sized neurons that coexpressed transient receptor potential vanilloid 1 ion channel and acid-sensing ion channel 3. Splanchnic nerve resection, but not vagotomy, affected the visceromotor response, and attenuated the ERK1/2 activation in DRG neurons produced by GD. Furthermore, intrathecal administration of the mitogen-activated protein kinase kinase 1/2 inhibitor, U0126, altered the response to noxious GD. CONCLUSIONS: The activation of ERK1/2 pathways in DRG neurons by noxious GD may be correlated with functional activity, and may be involved in acute visceral pain.

The patient with slightly elevated pancreatic enzymes and abdominal complaints.

Abdominal complaints in combination with slightly elevated serum pancreatic enzymes represent a classical clinical challenge. These symptoms may be due to coincidental unrelated harmless disorders, benign pancreatic alterations which are fairly easily treatable such as mild acute pancreatitis or uncomplicated chronic pancreatitis. However, serious, often insidious diseases such as pancreatic tumours may also present with this constellation as their first signs. Diagnostic procedures need to be stratified according to acuteness and severity of symptoms. While patients with acute onset of symptoms and severe complaints need immediate and combined laboratory and imaging investigations to allow adequate therapy, chronic and mild complaints usually justify a stepwise diagnostic approach consecutively using abdominal ultrasound, CT/MRI and endoscopic ultrasound as imaging procedures and reserving ERCP for cases which remain unclear or in which interventional therapy is needed. Diagnosis and follow-up are often particularly demanding in patients with cystic tumours of the pancreas. In chronic pancreatitis patients pain therapy and adequate control of pancreatic exocrine insufficiency may pose major problems. Patients with refractory pain may ultimately require surgical intervention. Another important indication for surgery in chronic pancreatitis is suspicion of cancer that cannot be ruled out by dedicated diagnostic procedures. This also applies to cystic tumours of the pancreas, which have a high risk of malignant transformation or may even already represent pancreatic cancer at the time of diagnosis.

Role for protease activity in visceral pain in irritable bowel syndrome.

Mediators involved in the generation of symptoms in patients with irritable bowel syndrome (IBS) are poorly understood. Here we show that colonic biopsy samples from IBS patients release increased levels of proteolytic activity (arginine cleavage) compared to asymptomatic controls. This was dependent on the activation of NF-kappaB. In addition, increased proteolytic activity was measured in vivo, in colonic washes from IBS compared with control patients. Trypsin and tryptase expression and release were increased in colonic biopsies from IBS patients compared with control subjects. Biopsies from IBS patients (but not controls) released mediators that sensitized murine sensory neurons in culture. Sensitization was prevented by a serine protease inhibitor and was absent in neurons lacking functional protease-activated receptor-2 (PAR2). Supernatants from colonic biopsies of IBS patients, but not controls, also caused somatic and visceral hyperalgesia and allodynia in mice, when administered into the colon. These pronociceptive effects were inhibited by serine protease inhibitors and a PAR2 antagonist and were absent in PAR2-deficient mice. Our study establishes that proteases are released in IBS and that they can directly stimulate sensory neurons and generate hypersensitivity symptoms through the activation of PAR2.