Enhanced cholinergic-mediated increase in the pro-inflammatory cytokine IL-6 in irritable bowel syndrome: role of muscarinic receptors.

OBJECTIVES: Irritable bowel syndrome (IBS) is a functional disorder, which has recently been linked to immune activation. We tested the hypothesis that the pro-inflammatory cytokine profile in IBS is driven by the cholinergic system and determined if the responses are mediated by muscarinic receptors. METHODS: Eighty-eight subjects took part in two studies, 37 IBS patients (Rome II), 14 depressed patients, and 37 healthy volunteers. Eighteen IBS patients had diarrhea predominant IBS, 14 were alternators, and 5 were predominantly constipated. In study 1, blood was drawn for baseline measurement of growth hormone (GH) and cytokines IL-6, IL-8, and IL-10. Pyridostigmine 120 mg was administered orally and further blood sampling took place for 180 min. In study 2, patients with IBS, depressed patients, and healthy subjects underwent the pyridostigmine test on two separate occasions with procyclidine (antimuscarinic) pre-treatment on one test occasion. Both GH and IL-6 were monitored. RESULTS: In study 1, baseline IL-6 (P= 0.003) and IL-8 levels (P= 0.001) were higher in IBS than in controls. Pyridostigmine stimulated the release of IL-6 and GH, but not IL-8 or IL-10; these responses were significantly augmented in IBS patients relative to controls. The IL-6 level following pyridostigmine administration correlated significantly with the symptom score (P < 0.01). In study 2, IL-6 rose following pyridostigmine in IBS but not depression and procyclidine blocked the rise. The GH response was abolished by procyclidine in all three groups. CONCLUSIONS: IBS and major depression are characterized by a pro-inflammatory profile, whereas IBS patients alone exhibit an exaggerated muscarinic receptor-mediated IL-6 response.

Cholecystokinin hyperresponsiveness in functional dyspepsia.

Functional dyspepsia (FD) is a common disorder of yet uncertain etiology. Dyspeptic symptoms are usually meal related and suggest an association to gastrointestinal (GI) sensorimotor dysfunction. Cholecystokinin (CCK) is an established brain-gut peptide that plays an important regulatory role in gastrointestinal function. It inhibits gastric motility and emptying via a capsaicin sensitive vagal pathway. The effects on emptying are via its action on the proximal stomach and pylorus. CCK is also involved in the regulation of food intake. It is released in the gut in response to a meal and acts via vagal afferents to induce satiety. Furthermore CCK has also been shown to be involved in the pathogenesis of panic disorder, anxiety and pain. Other neurotransmitters such as serotonin and noradrenaline may be implicated with CCK in the coordination of GI activity. In addition, intravenous administration of CCK has been observed to reproduce the symptoms in FD and this effect can be blocked both by atropine and loxiglumide (CCK-A antagonist). It is possible that an altered response to CCK may be responsible for the commonly observed gastric sensorimotor dysfunction, which may then be associated with the genesis of dyspeptic symptoms.

Role of cholecystokinin and central serotonergic receptors in functional dyspepsia.

Symptoms of functional dyspepsia are characterized by upper abdominal discomfort or pain, early satiety, postprandial fullness,bloating, nausea and vomiting. It is a chronic disorder, with symptoms more than 3 mo per year,and no evidence of organic diseases. Dysfunctional motility, altered visceral sensation, and psychosocial factors have all been identified as major pathophysiological mechanisms. It is believed that these pathophysiological mechanisms interact to produce the observed symptoms. Dyspepsia has been categorized into three subgroups based on dominant symptoms. Dysmotility-like dyspepsia describes a subgroup of patients whose symptom complex is usually related to a gastric sensorimotor dysfunction. The brain-gut peptide cholecystokinin (CCK) and serotonin (5-HT) share certain physiological effects. Both have been shown to decrease gastric emptying and affect satiety. Furthermore the CCK induced anorexia depended on serotonergic functions probably acting via central pathways. We believe that abnormalities of central serotonergic receptors functioning together with a hyper responsiveness to CCK or their interactions may be responsible for the genesis of symptoms in functional dyspepsia (FD).

Central serotonergic and noradrenergic receptors in functional dyspepsia.

Functional dyspepsia is a symptom complex characterised by upper abdominal discomfort or pain, early satiety, motor abnormalities, abdominal bloating and nausea in the absence of organic disease. The central nervous system plays an important role in the conducting and processing of visceral signals. Alterations in brain processing of pain, perception and affective responses may be key factors in the pathogenesis of functional dyspepsia. Central serotonergic and noradrenergic receptor systems are involved in the processing of motor, sensory and secretory activities of the gastrointestinal tract. Visceral hypersensitivity is currently regarded as the mechanism responsible for both motor alterations and abdominal pain in functional dyspepsia. Some studies suggest that there are alterations in central serotonergic and noradrenergic systems which may partially explain some of the symptoms of functional dyspepsia. Alterations in the autonomic nervous system may be implicated in the motor abnormalities and increases in visceral sensitivity in these patients. Noradrenaline is the main neurotransmitter in the sympathetic nervous system and again alterations in the functioning of this system may lead to changes in motor function. Functional dyspepsia causes considerable burden on the patient and society. The pathophysiology of functional dyspepsia is not fully understood but alterations in central processing by the serotonergic and noradrenergic systems may provide plausible explanations for at least some of the symptoms and offer possible treatment targets for the future.

"Best practice' for Helicobacter pylori eradication in the primary care setting.

This study determined the relative cost effectiveness of proton pump inhibitor (PPI) based triple therapy regimens for Helicobacter pylori eradication in the primary care setting. Using decision tree analysis the expected cost for each H. pylori eradication strategy was determined from the cost of each treatment option multiplied by the probability of that option occurring. Probabilities were obtained using the GMS prescribing database where all patients who received amoxycillin, clarithromycin and a PPI in the ERHA region in 2002 were followed for one year. Depending on the regimen adopted, 40.8% to 46.1% of patients did not require any further medication in the year following H. pylori eradication treatment. The strategy of rabeprazole, amoxycillin and clarithromycin was the most cost effective option with a cost of Euro466 per asymptomatic patient. Two-way sensitivity analysis indicated that the cost of rabeprazole triple therapy and the duration of rabeprazole maintenance therapy would each have to increase by 30% before this strategy ceased to be the most cost effective and hence best practice option for eradicating Helicobacter pylori in the primary care setting in Ireland.

Severity of cirrhosis and the relationship of alpha 1-acid glycoprotein concentration to plasma protein binding of lidocaine.

The concentration of alpha 1-acid glycoprotein, the major determinant of the plasma protein binding of basic drugs, and the extent of lidocaine protein binding was related to the severity of liver disease in 30 cirrhotic patients. In comparison with matched control subjects, alpha 1-acid glycoprotein concentration (77 +/- 7 versus 37 +/- 3 mg/dl; mean +/- SEM; p less than 0.01) and lidocaine binding (69% +/- 2% versus 35% +/- 2%; p less than 0.01) was markedly reduced. There was a significant negative correlation (r = 0.78; p less than 0.01) between free lidocaine and alpha 1-acid glycoprotein concentration. Furthermore, both were significantly related to the severity of liver disease, as assessed by use of the Child Turcotte classification.

Hepatic arterial and portal venous components of liver blood flow: a dynamic scintigraphic study.

Assessment of liver hemodynamics can be obtained by analysis of first pass flow studies through the liver and spleen using 99mTc compounds which are not actually trapped by these organs. This study examines new and existing methods for determining the relevant contribution made by the hepatic artery and portal vein to total liver blood flow, from these first pass studies. Eighty-two studies were performed in 56 patients with both normal and abnormal liver function. Using region of interest analysis, time-activity curves were obtained for the lungs, liver, spleen, and left kidney. These curves were analyzed by four different methods. Two of these methods are based upon measurement of the slopes of the uptake and washout curves from the liver and spleen and the other two methods employ deconvolution analysis to permit area measurement under the deconvolved curves as an indicator of blood flow. All four methods showed a small intraobserver variation after reanalysis. In 11 patients who underwent repeat studies, the correlation between the deconvolution based methods (r = 0.79-0.89) was significantly better than that for the slope based methods (r = 0.55-0.58). The deconvolution based methods provided the most significant separation between normals and patients with various liver disorders and would appear to be the most suitable techniques for monitoring the effects of various drugs and surgical procedures on the relative arterial/portal contribution to hepatic blood flow.

Effect of IL-4 on peripheral blood lymphocyte proliferation: implication in immunopathogenesis of H. pylori infection.

Interleukin (IL) 4 is a type 2 cytokine which has a negative immunoregulatory role in human infection. IL-4 suppresses the production of interferon-gamma and enhances IL-10 synthesis. However, the effect of IL-4 on proliferative response of lymphocytes remains to be elucidated. We have previously reported an increase in production of IL-4 in subjects with Helicobacter pylori (H. pylori) infection. To evaluate whether the increased IL-4 is responsible for the down-regulation of immune responses in H. pylori infection, we observed the proliferative response of peripheral blood lymphocytes (PBL) co-cultured with phythaemagglutinin (PHA) or H. pylori in the presence and absence of added IL-4. As we have previously shown, PHA and H. pylori may increase PBL proliferation (P < 0.001). An increase in PBL proliferation was observed when PBL were co-cultured with PHA (P < 0.001) or H. pylori (P < 0.001) in the presence of IL-4 compared to that in the absence of IL-4. The optimal dose of IL-4 to give maximal lymphocyte proliferation is 50 pg/ml for the PHA-stimulated group or 100 pg/ml for the H. pylori-stimulated group. The data suggest that the increased IL-4 does not directly contribute to suppressed lymphocyte proliferation in H. pylori infection. Further studies will be required to determine the role of IL-4 in other aspects of down-regulation of immune responses in H. pylori infection.

Review: lipoxygenase inhibitors and the gut.

Leukotriene synthesis is influenced by several drugs currently in use for the treatment of alimentary disease, including the corticosteroids, sulphasalazine and mesalazine. However, the use of selective lipoxygenase inhibitors in human gastrointestinal disease has not been investigated. The complexity of eicosanoid metabolism, and the incomplete knowledge of roles played by each metabolite in each tissue and disease condition, make rational pharmacological manipulation of arachidonate metabolism difficult. However, lipoxygenase inhibitors show promise in animal models of inflammation, including hepatitis, and studies in vitro suggest that therapeutic benefits may be achieved using inhibitors of leukotriene synthesis in other inflammatory disorders.

The effect of calcium channel blockade with nifedipine on splanchnic and systemic haemodynamics in cirrhosis.

The splanchnic and systemic haemodynamic effects of a single sublingual dose of nifedipine (slow calcium channel blocker) in nine patients with cirrhosis of the liver and portal hypertension were studied. Nifedipine produced a significant reduction in the mean arterial blood pressure (98 +/- 5.3 vs. 86 +/- 5 mmHg, P less than 0.05) but did not alter the mean heart rate, portal venous pressure or total liver blood flow. The systemic antihypertensive effect of nifedipine can be achieved without altering liver blood-flow in patients with chronic liver disease and portal hypertension.

A double-blind placebo-controlled study of buspirone-stimulated prolactin release in non-ulcer dyspepsia--are central serotoninergic responses enhanced?

BACKGROUND: Dyspepsia is a common symptom for which an organic cause is found in only 40% of patients. When no cause is apparent and the dyspepsia is considered to be idiopathic, a diagnosis of non-ulcer dyspepsia is made. The pathophysiology of non-ulcer dyspepsia is poorly understood and numerous theories have been put forward, including a theory of enhanced central serotoninergic receptor sensitivity. AIM: To determine the sensitivity of serotonin receptors in non-ulcer dyspepsia. METHODS: Using a randomized, double-blind, placebo-controlled design, we compared buspirone (a serotonin type 1a partial agonist)-stimulated prolactin release in 50 patients and 59 healthy comparison subjects. Buspirone, 30 mg, or matching placebo was administered on two separate occasions and prolactin release over 180 min was monitored. Patients and healthy subjects received both treatments in random order, 1 week apart. RESULTS: Overall, patients with non-ulcer dyspepsia had greater prolactin release in response to the buspirone challenge than the healthy comparison subjects, with differences most significant at 90 min following the challenge. Enhancement occurred in patients both with and without Helicobacter pylori infection. Female subjects, both patients and healthy volunteers, showed a greater response to buspirone than male subjects, and the augmentation of response observed in male and female patients was greater in females. CONCLUSIONS: Patients with non-ulcer dyspepsia have enhanced central serotoninergic responses and such responses are independent of H. pylori infection. Blockade of such receptors might be an appropriate therapeutic strategy.

Randomized comparison of unfractionated heparin with corticosteroids in severe active inflammatory bowel disease.

BACKGROUND: Heparin therapy may be effective in steroid resistant inflammatory bowel disease. AIM: A randomized pilot study, to compare unfractionated heparin as a first-line therapy with corticosteroids in colonic inflammatory bowel disease. METHODS: Twenty patients with severe inflammatory bowel disease (ulcerative colitis, n=17; Crohn's colitis, n=3) were randomized to either intravenous heparin for 5 days, followed by subcutaneous heparin for 5 weeks (n=8), or high-dose intravenous hydrocortisone for 5 days followed by oral prednisolone 40 mg daily, reducing by 5 mg per day each week (n=12). After 5 days, non-responders in each treatment group were commenced on combination therapy. Response to therapy was monitored by: clinical disease activity (ulcerative colitis: Truelove and Witt Index; Crohn's colitis: Harvey and Bradshaw Index), stool frequency, serum C-reactive protein and alpha1 acid glycoprotein, endoscopic and histopathological grading. RESULTS: The response rates were similar in both treatment groups: clinical activity index (heparin vs. steroid; 75% vs. 67%; P=0.23), stool frequency (75% vs. 67%; P=0.61), endoscopic (75% vs. 67%; P=0.4) and histopathological grading (63% vs. 50%; P=0.67). Both treatments were well-tolerated with no serious adverse events. CONCLUSION: Heparin as a first line therapy is as effective as corticosteroids in the treatment of colonic inflammatory bowel disease. Large multicentre randomized comparative studies are required to determine the role of heparin in the management of inflammatory bowel disease.

Reflux symptom relief with omeprazole in patients without unequivocal oesophagitis.

BACKGROUND: As many as 50% of patients with reflux symptoms have no endoscopic evidence of oesophagitis. This multicentre study was designed to assess symptom relief after omeprazole 20 mg once daily in patients with symptoms typical of gastro-oesophageal reflux disease but without endoscopic evidence of oesophagitis. METHODS: Patients (n = 209) were randomized in a double-blind study to receive either omeprazole 20 mg once daily (n = 98) or placebo (n = 111) for 4 weeks. Symptoms were assessed at clinic visits and using daily diary cards, with patient-completed questionnaires providing additional data on symptoms and on psychological disturbance. RESULTS: On completion, symptom relief favoured omeprazole: 57% of patients on omeprazole were free of heartburn (vs. 19% on placebo), 75% were free of regurgitation (47%) and 43% were completely asymptomatic (14%), each with P < 0.0001. Fewer patients in the omeprazole group required alginate/antacid relief medication (P < 0.05). Symptom relief (time to first heartburn-free day) was more rapid with omeprazole (2 vs. 5 days on placebo; P < 0.01). A greater reduction in anxiety occurred in the omeprazole group (P < 0.05). CONCLUSION: Omeprazole 20 mg once daily is effective in providing relief of the symptoms typical of gastro-oesophageal reflux disease in patients with essentially normal oesophageal mucosa.

Impact of cortisol on buspirone stimulated prolactin release: a double-blind placebo-controlled study.

Buspirone is known to stimulate prolactin release. Clinical studies (e.g. in chronic fatigue syndrome) suggest that the response may be influenced by baseline cortisol levels. We conducted a double-blind placebo-controlled study to examine the relationship between the prolactin response to buspirone challenge and baseline cortisol level. Fifty healthy volunteers took part in the study. Buspirone was found to consistently elevate PRL levels above those seen following placebo administration. The PRL response as measured by area under the curve was highly correlated with the baseline cortisol level.

Up-regulation of CD44 and ICAM-1 expression on gastric epithelial cells by H. pylori.

Interaction between lymphocytes and epithelial cells may play a key role in Helicobacter pylori (H. pylori)-associated gastric mucosal inflammation. This interaction process is at least partially mediated by various cell adhesion molecules. The aims of the present study were to assess using flow cytometric analysis whether H. pylori directly or supernatants from H. pylori-activated peripheral blood mononuclear cells (PBMC) can affect the expression of adhesion molecules on the gastric epithelial cell line AGS in vitro. The results showed that resting AGS cells expressed CD44 and ICAM-1. Co-culture of AGS with H. pylori or cytokine-rich supernatants from H. pylori-activated PBMC resulted in up-regulation of expression of CD44 and ICAM-1 on AGS cells. These data suggest that H. pylori directly and indirectly through inflammatory cytokines may contribute to alternations in adhesion molecule expression on gastric epithelial cells. This may be of pathological significance in H. pylori-associated gastric mucosal inflammation and carcinogenesis.

Helicobacter pylori-induced lipid peroxidation in peripheral blood lymphocytes.

Several lines of evidence implicate Helicobacter pylori infection in the pathogenesis of gastritis and peptic ulceration. To investigate whether H. pylori can cause lipid peroxidation in lymphocytes in vitro and to look for experimental evidence of lipid peroxidation induced by H. pylori, the lipid peroxide (LPO) level in peripheral blood lymphocytes was measured using the thiobarbituric acid fluorescence method. In the absence of added H. pylori, the LPO level in lymphocytes was 0.133 +/- 0.033 nmol/10(6) cells, and in the co-culture of H. pylori with peripheral blood mononuclear cells 0.340 +/- 0.097 nmol/10(6) cells. A significant difference was found between the two groups (p < 0.001). Antioxidants, either superoxide dismutase or catalase, could inhibit LPO production in lymphocytes. The present data provide further evidence that H. pylori can induce lipid peroxidation, which may be responsible for the pathogenesis of H. pylori-associated mucosal damage.

Increased gastric production of interleukin-8 and tumour necrosis factor in patients with Helicobacter pylori infection.

AIMS: To investigate the role of interleukin-8 (IL-8) and tumour necrosis factor (TNF) in patients infected with Helicobacter pylori. METHODS: The study population comprised 52 patients with dyspepsia attending for upper gastrointestinal endoscopy. Of these patients, 35 were infected with H pylori. IL-8 and TNF concentrations in plasma, gastric juice, and gastric biopsy homogenate supernatant fluid were measured by radioimmunoassay and L929 cell bioassay, respectively. RESULTS: The concentrations of IL-8 and TNF in gastric juice and gastric biopsy homogenates were substantially greater in patients infected with H pylori. In H pylori positive patients IL-8 concentrations in gastric juice and gastric biopsy homogenates were higher in those with moderate gastritis than in those with mild gastritis. There was a positive correlation between IL-8 and TNF concentrations in gastric juice and gastric biopsy homogenate supernatant fluid from H pylori positive patients. There were no significant differences between H pylori positive and negative patients with respect to IL-8 and TNF plasma concentrations. CONCLUSION: This study suggests that increased gastric production of IL-8 and TNF may be implicated in the pathogenesis of H pylori associated gastroduodenal disease.

Molecular analysis of Helicobacter pylori populations in antral biopsies from individual patients using randomly amplified polymorphic DNA (RAPD) fingerprinting.

In the present study, randomly amplified polymorphic DNA (RAPD) fingerprinting has been used to analyse multiple single colony isolates of Helicobacter pylori from antral biopsies in an attempt to ascertain whether or not multiple strains are present in individual patients using single biopsy samples. The RAPD fingerprints derived from single colonies obtained from the same biopsy specimen were in all cases indistinguishable. The previously noted heterogeneity between H. pylori strains from different individuals was confirmed. RAPD fingerprinting, combined with a simple method of template preparation, was shown to be an excellent method for H. pylori strain differentiation. The results of this study indicate that the H. pylori population is homogeneous in individual patients at a single gastric site.

Pseudomonas aeruginosa cross-infection following endoscopic retrograde cholangiopancreatography.

In a 6 week period, three of 50 patients developed Pseudomonas aeruginosa septicaemia following Endoscopic Retrograde Cholangiopancreatography (ERCP). Pseudomonas aeruginosa serotype 10 was isolated from each of the patients and from the endoscope. The outbreak was related to inadequate disinfection of the air and water channel of the endoscope. Following the introduction of a modified decontamination technique, which involved rinsing the air and water channel with glutaraldehyde, no further cases of pseudomonas infection occurred, and the organism could not be isolated from the instrument. Obstruction of the biliary tract was a predisposing factor in the development of infection; and administration of antibiotics immediately following the procedure failed to prevent it. This may have been due to inadequate dosage. We suggest that patients presenting for ERCP, in whom obstruction of the biliary tract is suspected, should come prepared for immediate drainage of the obstructed system at the time of the procedure.

Adhesion molecule expression on gastric intra-epithelial lymphocytes of patients with Helicobacter pylori infection.

OBJECTIVE: To examine the expression of adhesion molecules on gastric intra-epithelial lymphocytes (IELs) from patients infected with Helicobacter pylori. DESIGN: The expression of adhesion molecules and T-cell activation markers by gastric IELs from patients with gastritis or duodenal ulceration was examined using two-colour flow cytometry. Ten of the patients were H. pylori positive and eight were H. pylori negative. RESULTS: Expression of lymphocyte function-associated antigen-1 (LFA-1) on IELs was significantly lower (P < 0.05) in patients with H. pylori infection than in patients negative for H. pylori. There were no significant differences in the expression on IELs of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), human mucosal lymphocyte (antigen)-1 (HML-1), very late antigen-4 (VLA-4) or CD43 between H. pylori-positive and H. pylori-negative individuals. In addition, the transferrin receptor, a maker associated with proliferation and activation, was found on a small population of IELs from H. pylori-positive individuals. CONCLUSION: A reduction in the expression of LFA-1 has previously been reported on activation of IELs. The finding of reduced LFA-1 expression and increased transferrin receptor expression on IELs from H. pylori-positive individuals suggests that activation of these cells is associated with H. pylori infection.