Potent inhibition of gastric acid secretion and ulcer formation by centrally and peripherally administered interleukin-1

Intricate Connections between the Microbiota and Endometriosis

Imbalances in gut and reproductive tract microbiota composition, known as dysbiosis, disrupt normal immune function, leading to the elevation of proinflammatory cytokines, compromised immunosurveillance and altered immune cell profiles, all of which may contribute to the pathogenesis of endometriosis. Over time, this immune dysregulation can progress into a chronic state of inflammation, creating an environment conducive to increased adhesion and angiogenesis, which may drive the vicious cycle of endometriosis onset and progression. Recent studies have demonstrated both the ability of endometriosis to induce microbiota changes, and the ability of antibiotics to treat endometriosis. Endometriotic microbiotas have been consistently associated with diminished Lactobacillus dominance, as well as the elevated abundance of bacterial vaginosis-related bacteria and other opportunistic pathogens. Possible explanations for the implications of dysbiosis in endometriosis include the Bacterial Contamination Theory and immune activation, cytokine-impaired gut function, altered estrogen metabolism and signaling, and aberrant progenitor and stem-cell homeostasis. Although preliminary, antibiotic and probiotic treatments have demonstrated efficacy in treating endometriosis, and female reproductive tract (FRT) microbiota sampling has successfully predicted disease risk and stage. Future research should aim to characterize the "core" upper FRT microbiota and elucidate mechanisms behind the relationship between the microbiota and endometriosis.

Gastric acid, calcium absorption, and their impact on bone health

Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.

Influence of Helicobacter pylori infection on gastric acid secretion in pre-school Bangladeshi children

BACKGROUND

The effect of Helicobacter pylori (H. pylori) infection on gastric acid secretion (GAS) is poorly defined in children.

OBJECTIVE

To determine whether H. pylori infection is associated with abnormal GAS in children.

METHODS

We studied 30 H. pylori-infected children (identified by a positive urea breath test) and 30 noninfected children of both sexes, aged 2-5 years. Gastric pH and GAS were measured before and 8 weeks after the completion of a 2-week course of anti- H. pylori therapy (omeprazole, clarithromycin, and amoxicillin). Gastric acid output (GAO) was quantified during a 1-h basal period (GAO-B) (mmol/h) and a 1-hour stimulated period (GAO-S) (mmol/hour) following subcutaneous administration of pentagastrin (6 μg/kg).

RESULTS

A significantly greater number of infected children had a high gastric pH (>4.0, p = 0.03) compared with the noninfected group. GAO-B and GAO-S in H. pylori-infected children were significantly lower, around 50%, compared with children without H. pylori infection. H. pylori-eradication therapy resulted in a rise of both the mean GAO-B (paired t-test before vs. after therapy; 0.28 ± 0.40 vs. 0.62 ± 1.0, p = 0.12) and GAO-S (before vs. after therapy; 2.0 ± 1.4 vs. 3.4 ± 2.5, p = 0.001), with values reaching equivalence to those in the H. pylori-negative children (0.71 ± 0.56 for BAO, 3.3 ± 2.0 for SAO, p = NS).

CONCLUSION

The results suggest that the gastric barrier is compromised in children with H. pylori infection in Bangladesh. Improvement of GAO following anti- H. pylori therapy suggests a causal link between H. pylori infection and depressed GAO in this population.

Rebound acid hypersecretion after withdrawal of gastric acid suppressing drugs: new evidence of similitude

BACKGROUND

Homeopathy is based on the principle of similitude (similia similibus curentur) using medicines that cause effects similar to the symptoms of disease in order to stimulate the reaction of the organism. Such vital, homeostatic or paradoxical reaction of the organism is closely related to rebound effect of drugs.

METHOD

Review of the literature concerning the rebound effects of drugs used to suppress gastric acidity, particularly proton pump inhibitors (PPIs).

RESULTS

The mechanism of action of these effects is discussed. Rebound in terms of clinical symptoms and physiological effects occur in about 40% of people taking PPIs, their timing depends on the half-life of the drug and the adaptation period of the physiological mechanisms involved. The wide use of PPIs may be linked to the rising incidence of carcinoid tumours.

CONCLUSIONS

These findings support Hahnemann's concept of secondary action of drugs. We are developing a homeopathic materia medica and repertory of modern drugs on the basis of reported rebound effects.

Inhibitor of kappaB kinase beta regulates gastric carcinogenesis via interleukin-1alpha expression

BACKGROUND & AIMS

Nuclear factor-kappaB (NF-kappaB) is an important transcription factor involved in various biological processes, including carcinogenesis. However, it is unknown whether NF-kappaB activation is involved in gastric carcinogenesis.

METHODS

To explore the roles of inhibitor of kappaB kinase (IKKbeta), the key kinase for NF-kappaB activation, in gastric epithelium, we established a conditional gastric mucosal epithelium knockout mouse (Ikkbeta(DeltaST)). Gastric cancer was induced using N-methyl-N-nitrosourea (MNU). After 8 months, the number of tumors and their sizes were evaluated. Apoptosis was analyzed by terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling staining, and levels of inflammatory cytokines were measured.

RESULTS

No phenotypical or histologic difference was observed between untreated Ikkbeta(DeltaST) and controls (Ikkbeta(F/F)). The number of tumors was significantly less in the MNU-treated Ikkbeta(DeltaST) group than in the Ikkbeta(F/F) group (mean +/- standard error, 2.21 +/- 0.48 vs 0.80 +/- 0.23), and the size of the tumors did not differ (2.75 +/- 0.99 vs 2.89 +/- 1.12 mm). After a single oral dose of MNU, interleukin (IL)-1alpha was up-regulated significantly in control mice compared with Ikkbeta(DeltaST) mice, whereas the levels of IL-1beta, IL-6, and tumor necrosis factor-alpha were unchanged. MNU significantly increased apoptotic cell death in Ikkbeta(DeltaST) mice compared with Ikkbeta(F/F) mice, and apoptosis was dependent on decreased IL-1alpha expression. IL-1alpha also induced the proliferation of gastric cancer cells. Fewer tumors were observed in IL-1-receptor knockout mice (Il-1r(-/-); 1.17 +/- 0.44) than in control mice (2.42 +/- 0.52).

CONCLUSIONS

IKKbeta regulates gastric carcinogenesis via IL-1alpha expression, which is associated with anti-apoptotic signaling and cell proliferation.

Effect of Helicobacter pylori eradication on incidence of gastric cancer in human and animal models: underlying biochemical and molecular events

BACKGROUND

Gastric cancer remains one of the most common cancers worldwide. A strong association exists between Helicobacter pylori infection and the risk of developing noncardia gastric cancer. H. pylori eradication by antibiotic treatment is regarded as a primary chemoprevention strategy to reduce gastric cancer incidence.

AIM

To analyze the efficacy of H. pylori eradication in preventing gastric cancer in human and animal models, and to discuss whether biochemical, genetic, and epigenetic changes associated with H. pylori infection are reversible after curing the infection.

RESULTS

Several intervention trials have indicated that in some patients, H. pylori eradication leads to regression and prevents the progression of precancerous lesions. The eradication therapy reduces gastric cancer incidence in patients without any precancerous lesions at the baseline and is most effective before the development of atrophic gastritis. A few recent intervention studies in Japan have demonstrated significant prophylactic effects of eradication therapy on the development of gastric cancer, suggesting the use of eradication therapy in high-risk populations as a gastric cancer reduction strategy. However, gastric cancer may still develop despite successful eradication therapy. Studies in animal models have confirmed the use of eradication therapy at an early point of infection to prevent gastric cancer development.

CONCLUSION

H. pylori eradication may not completely abolish the risk of gastric cancer. However, eradication therapy may be used in high-risk populations to reduce gastric cancer incidence. It can reverse many biochemical, genetic, and epigenetic changes that H. pylori infection induces in the stomach.

Role of brainstem TRH/TRH-R1 receptors in the vagal gastric cholinergic response to various stimuli including sham-feeding

Pavlov's pioneering work established that sham-feeding induced by sight or smell of food or feeding in dogs with permanent esophagostomy stimulates gastric acid secretion through vagal pathways. Brain circuitries and transmitters involved in the central vagal regulation of gastric function have recently been unraveled. Neurons in the dorsal vagal complex including the dorsal motor nucleus of the vagus (DMN) express thyrotropin-releasing hormone (TRH) receptor and are innervated by TRH fibers originating from TRH synthesizing neurons in the raphe pallidus, raphe obscurus and the parapyramidal regions. TRH injected into the DMN or cisterna magna increases the firing of DMN neurons and gastric vagal efferent discharge, activates cholinergic neurons in gastric submucosal and myenteric plexuses, and induces a vagal-dependent, atropine-sensitive stimulation of gastric secretory (acid, pepsin) and motor functions. TRH antibody or TRH-R1 receptor oligodeoxynucleotide antisense pretreatment in the cisterna magna or DMN abolished vagal-dependent gastric secretory and motor responses to sham-feeding, 2-deoxy-D-glucose, cold exposure and chemical activation of cell bodies in medullary raphe nuclei. TRH excitatory action in the DMN is potentiated by co-released prepro-TRH-(160-169) flanking peptide, Ps4 and 5-HT, and inhibited by a number of peptides involved in the stress/immune response and inhibition of food-intake. These neuroanatomical, electrophysiological and neuropharmacological data are consistent with a physiological role of brainstem TRH in the central vagal stimulation of gastric myenteric cholinergic neurons in response to several vagal dependent stimuli including sham-feeding.

Indicaciones y consecuencias de la erradicación de Helicobacter pylori en la enfermedad por reflujo gastroesofágico

Several epidemiological data indicate that H. pylori infection prevalence in patients with gastroesophageal reflux disease (GERD) is lower than that reported in respective controls, which would suggest that the organism plays a protective role against this disease. On the other hand, most studies demonstrate that the presence of the infection in patients with GERD does not negatively affect the therapeutic efficacy of proton pump inhibitors (PPIs), and, in case of negatively influencing it, the effects are not clinically relevant and are easily controllable with standard antisecretory treatment. Therefore, the decision to administer H. pylori eradication treatment to a patient should not be influenced by the concomitant presence of GERD. In most cases, H. pylori eradication does not seem to induce GERD development, and it does not seem to worsen GERD when it was already present. Nevertheless, when the gastritis pattern is unknown before the antibiotic administration, the effect of H. pylori eradication on gastric acid secretion and the incidence of GERD is unpredictable. In the exceptional cases in which H. pylori eradication could have negative effects on GERD, its clinical relevance will be limited, and reflux symptoms or endoscopic esophagitis will favourably respond to the standard PPI antisecretory treatment. Therefore, again, when H. pylori eradication is indicated in a particular patient, the concomitant diagnosis of GERD should not change our attitude. Finally, is has recently been recommended to eradicate H. pylori infection in those patients with GERD needing long-term treatment with PPI, as some studies have reported that these drugs induce, in presence of the organism, an atrophic gastritis, with the consequent risk of gastric cancer. However, most of these studies have important methodological defects, and several authors have reported contrary results. In any case, the appearance in the gastric mucosa of clinically relevant lesions, such as intestinal metaplasia, dysplasia or adenocarcinoma, in patients treated with PPI for several years, has not yet been demonstrated, although this could simply be a problem of time. This question seems to be too controversial to be answered with the available data, and we should wait until new studies clarify this topic. In the meantime, as it occurs with any controversial indication, the decision of the doctor facing a patient infected by H. pylori and needing maintenance therapy with PPIs should be assessed on a case by case basis.

Endometriosis is associated with an altered profile of intestinal microflora in female rhesus monkeys

BACKGROUND

The intestinal microflora provide a strong defence against intestinal pathogens, and may be altered in inflammatory conditions that impact the gut, such as endometriosis. Therefore, intestinal bacteria shed from rhesus monkeys with endometriosis were compared with age-matched healthy controls. A second study assessed the prevalence of intestinal inflammation in female monkeys to determine whether endometriosis is associated with an increased likelihood of intestinal inflammation.

METHODS

Differential and selective agars were used to enumerate total and Gram-negative aerobic and facultatively anaerobic bacteria, as well as Lactobacilli, from female monkeys with or without endometriosis. In addition, the prevalence of intestinal inflammation in monkeys with or without endometriosis was determined in a retrospective analysis of necropsy reports.

RESULTS

Monkeys with endometriosis had a significantly different profile of shed microflora. Endometriosis was associated with lower Lactobacilli concentrations and higher Gram-negative bacteria concentrations. Moreover, there was a higher prevalence of intestinal inflammation in monkeys with endometriosis in comparison to healthy controls.

CONCLUSIONS

Endometriosis is associated with an altered profile of intestinal microflora in rhesus monkeys. Although the exact mechanisms linking endometriosis and the microflora are unknown, it is possible that the microflora were affected by endometriosis-associated intestinal inflammation.

Effect of purified lipopolysaccharides from strains of Helicobacter pylori and Helicobacter felis on acid secretion in mouse gastric glands in vitro

As a bacterial product, Helicobacter pylori lipopolysaccharide (LPS) can originate in close proximity to parietal cells, but the role of this uniquely structured endotoxin on acid secretion has not been fully investigated and remains unclear. The purpose of this study was to test the direct effect of purified LPS (tested range, 0.1 to 100 microg/ml) from various strains of H. pylori and from one Helicobacter felis strain on histamine- and carbachol-stimulated acid secretion in vitro using mouse gastric glands and the accumulation of [(14)C]aminopyrine. In addition, we investigated whether H. pylori LPS can interfere with two native antisecretory substances, prostaglandin E(2) (PGE(2)) and somatostatin, which may contribute to bacterial pathogenicity. Except for the LPS from H. pylori SS1 (Sydney strain), which gave a statistically significant increase in both histamine- and carbachol-stimulated acid output (38 and 24%, respectively; P < 0.05), no effect of the tested LPS was observed on acid secretion. H. pylori LPS purified from a patient isolate did not affect the potency or the efficacy of the inhibitory dose response curve to PGE(2) or somatostatin. Bacterial interstrain variation in the direct stimulatory effect of Helicobacter-derived LPS on acid secretion was observed, which probably reflects the molecular structure of LPS and the potential to contribute to virulence. Importantly, the data showed that H. pylori LPS did not have any direct antisecretory properties. It can be speculated that the acid stimulatory properties of LPS from H. pylori SS1 may contribute to the gastric damage observed in the mouse model of H. pylori infection.

Inhibition of carbachol stimulated acid secretion by interleukin 1beta in rabbit parietal cells requires protein kinase C

BACKGROUND

Interleukin 1beta (IL-1beta) is a potent inhibitor of gastric acid secretion. Regulatory actions at several levels have previously been demonstrated, including direct inhibition of parietal cell acid secretion. Although IL-1beta may activate several intracellular signalling pathways, the mechanisms responsible for inhibition of carbachol stimulated acid secretion have not been determined.

AIMS

To investigate the roles of protein kinase C (PKC) and the sphingomyelinase signalling pathways in the regulation of acid secretion by IL-1beta.

METHODS

Rabbit parietal cells were obtained by collagenase-EDTA digestion and centrifugal elutriation. Acid secretion stimulated by carbachol and A23187 (to mimic elevations in intracellular calcium) was assessed by 14C aminopyrine uptake in response to IL-1beta, PKC, and sphingomyelinase manipulation.

RESULTS

IL-1beta inhibited carbachol and A23187 stimulated acid secretion in a dose dependent manner. The inhibitory actions were completely reversed by each of three different PKC inhibitors, staurosporine, H-7, and chelerythrine, as well as by PKC depletion with high dose phorbol ester pretreatment. IL-1beta did not downregulate parietal cell muscarinic receptor. IL-1beta significantly increased membrane PKC activity. Activation of the sphingomyelinase/ceramide pathway had no effect on basal or stimulated acid secretion. The inhibitory action of IL-1beta was independent of protein kinase A and protein kinase G activity.

CONCLUSIONS

IL-1beta directly inhibits parietal cell carbachol stimulated acid secretion. This action occurs distal to muscarinic receptor activation and elevations in intracellular calcium and requires PKC.

Expression of intrinsic factor in rat and murine gastric mucosal cell lineages is modified by inflammation

Intrinsic factor is produced primarily by chief cells in rat and mouse, but 4 to 11% of isolated rat parietal cells also contain intrinsic factor. To test whether local conditions could alter the distribution of intrinsic factor expression, two rodent models of chronic lymphocytic gastric inflammation were examined. Immunocytochemistry was performed using antiserum against human intrinsic factor and H/K ATPase (a parietal cell marker), counting the percent of intrinsic factor-positive parietal cells. HLA-B27 transgenic rats develop chronic gastritis at age 3 months. Congenic controls expressed intrinsic factor in 8.9 +/- 3.8% (mean +/- SD) of parietal cells; in inflamed areas of transgenic rats 21 +/- 5.2% (P < 0.0001) of parietal cells were positive. In adjacent areas without inflammatory infiltrate 16 +/- 3.6% of parietal cells contained intrinsic factor. C57BL/6 mice inoculated with Helicobacter felis develop gastritis by 4 weeks. After 4 and 8 weeks of infection, intrinsic factor-positive parietal cells increased from 7.8 +/- 2.8% in the congenic controls to 17.6 +/- 4.1% in the inflamed gastric body (P < 0.0001). Isolated rat parietal cells incubated with interleukin-1beta demonstrated a twofold increase in intrinsic factor-positive parietal cells. These studies are consistent with the concept that intrinsic factor expression is both predetermined in chief cells and can be expressed in parietal cells in response to local inflammatory factors. The differences between inflamed and adjacent noninflamed areas in the rat model suggest a tissue gradient of soluble inducer(s), possibly cytokines.

Review article: the clinical influence of Helicobacter pylori in effective acid suppression-implications for the treatment of gastro-oesophageal reflux disease

The relationship between gastro-oesophageal reflux disease (GERD) and Helicobacter pylori is unclear. Recent data indicate that H. pylori probably exerts a protective effect against GERD. In recent years, the interaction between H. pylori, proton pump inhibitors and GERD has been widely studied. Currently available proton pump inhibitors produce significantly higher intragastric pH in H. pylori-positive patients than in those who are H. pylori negative, and this phenomenon may be clinically relevant. The mechanisms responsible for this difference in efficacy are not fully understood, although there are two major theories. Ammonia, produced by H. pylori, is able to neutralize gastric acid, and thus apparently increase the effect of acid suppressive agents (the 'ammonia theory'). The other theory is that decrease in acid output is due to the development of corpus gastritis during treatment with a proton pump inhibitor (the 'gastritis theory'). Treatment strategies to overcome this lowered sensitivity to acid suppression are to increase the frequency/dose of a proton pump inhibitor or to add an H2-receptor antagonist in the evening-but both have pharmaco-economic implications. An agent that could provide adequate pH control regardless of H. pylori status would be highly beneficial in the treatment of GERD, and may also lower treatment costs.

Will Helicobacter pylori affect short-term rebleeding rate in peptic ulcer bleeding patients after successful endoscopic therapy?

OBJECTIVE

Helicobacter pylori (H. pylori) can augment the pH-increasing effect of omeprazole in patients with peptic ulcer. A high intragastric pH may be helpful in preventing recurrent hemorrhage by stabilizing the blood clot at the ulcer base of bleeding peptic ulcer patients. Therefore, we hypothesized that omeprazole may reduce short-term rebleeding rate in these patients with H. pylori infection after initial hemostasis had been obtained.

METHODS

Between July 1996 and December 1998, 65 bleeding peptic ulcer patients (24 gastric ulcer, 41 duodenal ulcer) who had obtained initial hemostasis with endoscopic therapy were enrolled in this trial. Thirty (46.2%) of them were found to have H. pylori infection by a rapid urease test and pathological examination. For all studied patients, omeprazole was given 40 mg intravenously every 6 h for 3 days. Thereafter, omeprazole was given 20 mg per os (p.o.) once daily for 2 months. A pH meter was inserted in the fundus of each patient under fluoroscopic guidance after intravenous omeprazole had been administered. The occurrence of rebleeding episode was observed for 14 days.

RESULTS

In patients with H. pylori infection, intragastric pH (median, 95% confidence interval [CI]: 6.54, 5.90-6.68) was higher than in those without H. pylori infection (6.05, 5.59-6.50, p < 0.001). However, the patients with rebleeding (2 vs 3), volume of blood transfusion (median, range: 1000 ml, 0-2250 vs 750, 0-2000), number of operations (0 vs 1), mortality caused by bleeding (0 vs 0), and hospital stay (median, range: 6 days, 3-14 vs 7, 5-16) were not statistically different from those without H. pylori infection.

CONCLUSIONS

Omeprazole does increase intragastric pH in bleeding peptic ulcer patients with H. pylori infection. However, the presence of H. pylori infection does not affect the short-term rebleeding rate in these patients.

Induction of nociceptive responses by intrathecal injection of interleukin-1 in mice

Intrathecal (i.t.) injection (between lumbar vertebrae 5 and 6) into mice of a markedly low dose of IL-1alpha (3x10(-4) fmol or 5.4 fg in 5 microl per mouse) induced behaviors involving scratching, biting, and licking of non-stimulated hindpaws. The IL-1-induced behaviors appeared within 10 min of the injection of IL-1alpha, peaked at 20-40 min, and had disappeared 60 min after the injection. The IL-1-induced behaviors were similar to the nociceptive responses induced in mice by i.t. injection of substance P (SP) or subcutaneous (s.c.) injection of formalin into the footpad. The IL-1-induced behaviors were suppressed by intraperitoneal morphine, indicating that they are nociceptive responses. The nociceptive responses induced by 3x10(-4) (5.4 fg) of IL-1alpha were almost completely suppressed by co-injection of 0.3 fmol (7.2 pg) of an IL-1 receptor antagonist (IL-1ra). An antiserum against substance P, but not an antiserum against somatostatin, suppressed the IL-1-induced nociceptive responses. The nociceptive responses induced by s.c. injection of 2% formalin into the footpad were also inhibited by i.t. injection of 30 pmol (720 ng) of IL-1ra. These results suggest that IL-1 may play a role in hyperalgesia in mice by acting as a factor augmenting pain transmission in the spinal cord at least in part by either directly or indirectly releasing substance P.

Induction by interleukin-1, tumor necrosis factor and lipopolysaccharides of histidine decarboxylase in the stomach and prolonged accumulation of gastric acid

1. Injection of interleukin-1 (IL-1) into pylorus-ligated rats has been shown strongly to inhibit gastric secretion. However, in the present study, we found that an intraperitoneal injection of IL-1 into intact (non-pylorus-ligated) fasted mice rapidly (within 30 min) induced an accumulation of gastric acid ('early response'). When the dose of IL-1 was larger, the accumulation lasted for a longer period. 2. Injection of IL-1 also caused a later elevation of the activity of histidine decarboxylase (HDC), the histamine-forming enzyme, in the stomach ('later response'). 3. Cimetidine, an antagonist of histamine H2-receptors, suppressed the accumulation of gastric acid in both the early and later periods. An irreversible inhibitor of HDC, alpha-fluoromethylhistidine, partially inhibited the accumulation in the later period. 4. IL-1, when injected 1 h after feeding in mice fasted overnight, markedly retarded gastric emptying. 5. Tumour necrosis factor (TNF) and lipopolysaccharide (LPS) or endotoxin from E. coli both had IL-1-like effects on the stomach, and their effects are presumably mediated by IL-1. 6. These results support the idea that an inhibition of gastric emptying and an elevation of HDC activity in the stomach may explain the findings that a long-lasting accumulation of gastric acid is induced by IL-1 despite its potent inhibition of gastric acid secretion. 7. On the basis of these results, and in the light of the known actions of histamine, the possible roles of IL-1 in gastric inflammation and ulceration are discussed.

Relative contributions of peripheral and central sources to levels of IL-1 alpha in the cerebral cortex of mice: assessment with species-specific enzyme immunoassays

The peripheral administration or release of cytokines is associated with central nervous system (CNS) effects that are often due to the actions of cytokines behind the blood-brain barrier (BBB). It is not known whether the majority of cytokine behind the BBB is derived from blood or is released from the CNS in response to peripheral signals. We addressed this question for interleukin-1 alpha (IL-1 alpha) by infusing human IL-1 alpha (humIL-1 alpha) into mice and measuring humIL-1 alpha and murine IL-1 alpha (murIL-1 alpha) in cerebral cortex and serum with specific, sensitive enzyme immunoassays. In adult mice receiving 50 micrograms/kg-24 h of humIL-1 alpha subcutaneously for 48 h, brain and blood samples contained humIL-1 alpha but no murIL-1 alpha. This shows that in our study blood-borne IL-1 alpha did not self-stimulate its release in blood or brain. The presence of humIL-1 alpha in brain could only have originated from blood, where it was administered; the brain/blood ratio of 0.126 ml/g indicates that at steady state, brain levels reach about 12% of blood levels. In neonatal mice, both murIL-1 alpha and humIL-1 alpha were detected in brain and blood after the acute subcutaneous injection of humIL-1 alpha. However, the vast majority of immunoactivity in blood and brain was humIL-1 alpha. These results show that most of the IL-1 alpha appearing in response to circulating IL-1 alpha in areas of the CNS behind the BBB is due to passage across the BBB and not to release from stores endogenous to the CNS.

Mucosal interleukin-1 beta production and acid secretion in enlarged fold gastritis

BACKGROUND

We have previously shown that eradication of Helicobacter pylori increases acid secretion in H. pylori-associated enlarged fold gastritis.

AIM

To investigate whether locally produced interleukin-1 beta is possibly involved in the inhibition of acid secretion in H. pylori gastritis.

METHODS

IL-1 beta release from the gastric body mucosa was determined by short-term culture of biopsy specimens in 13 patients with enlarged fold gastritis (all H. pylori-positive), five H. pylori-positive and 10 H. pylori-negative patients without enlarged folds. The acid-inhibitory effect of locally produced IL-1 beta was examined by [14C]-aminopyrine uptake assay using isolated rabbit gastric glands.

RESULTS

IL-1 beta release was significantly greater in patients with enlarged fold gastritis, significantly correlated with both basal and tetragastrin-stimulated acid outputs in the H. pylori-positive patients (r = -0.591 and r = -0.641, respectively; P < 0.01), and significantly decreased with concomitant increases in acid secretions after eradication of H. pylori. [14C]-aminopyrine uptake was inhibited by IL-1 beta in a dose-dependent manner.

CONCLUSIONS

Increased production of IL-1 beta caused by H. pylori infection is possibly involved in the inhibition of acid secretion in enlarged fold gastritis.

Intragastric pH during treatment with omeprazole: role of Helicobacter pylori and H. pylori-associated gastritis

BACKGROUND

Omeprazole treatment produces lower intragastric pH values 4 weeks after cure of Helicobacter pylori infection than before. We therefore investigated the effect of healing H. pylori-associated gastritis on intragastric pH in the presence and in the absence of omeprazole therapy.

METHODS

Before and on day 8 of omeprazole, 20 mg once daily, 24-h intragastric pH-recordings were performed in 14 subjects with H. pylori infection and repeated 4 and 52 weeks after cure of infection. Gastritis severity in corpus and antrum was graded by using a modified Sydney system.

RESULTS

In the absence of omeprazole administration, median 24-h pH values before cure did not differ from those 4 and 52 weeks after cure. On day 8 of omeprazole administration, 24-h pH values were much higher before cure (median, 5.15; 95% confidence interval (CI), 4.3-6.0) than 4 weeks (3.6; 2.1-4.4; P < 0.001) and 52 weeks after cure (3.0; 2.1-4.4; P < 0.001). The activity of corpus and antral gastritis was not associated with the magnitude of H+ change induced by omeprazole.

CONCLUSION

The increased pH produced by omeprazole during H. pylori infection is likely to be due to neutralizing substances produced by H. pylori and not to H. pylori-induced gastritis.

Use of animal models in peptic ulcer disease

Considerable progress has been made in the understanding of the formation of gastric erosions by the use of animals. The role of gastric acid secretion in their pathogenesis has been clarified. Gastric erosions are associated with the presence of acid in the stomach and slow gastric contractions. With several different experimental procedures, the animal's body temperature falls; preventing the fall averts erosions. A fall in body temperature or exposure to cold are associated with the secretion of thyrotropin-releasing hormone (TRH), and both increased and decreased concentration of corticotropin-releasing factor (CRH) in discrete regions of rat brains. Thyrotropin-releasing hormone when injected into specific sites in the brain produces gastric erosions and increases acid secretion and slow contractions, whereas CRH has the opposite effects. One of the major sites of interaction of the two peptides is in the dorsal motor complex of the vagus nerve. Thyrotropin-releasing hormone increases serotonin (5-HT) secretion into the stomach. Serotonin counter-regulates acid secretion and slow contractions. Many other peptides injected into discrete brain sites stimulate or inhibit gastric acid secretion.

Ethanol-induced gastrointestinal damage. Influence of endogenous antioxidant components and gender

This study compared the effects of undiluted and 8% ethanol administered orally on gastrointestinal antioxidant components of male and female rats. Eight percent ethanol increased the activities of duodenal glutathione peroxide (29% in males, 14% in females) and superoxide dismutase in female gastric (24%) and male duodenal (15%) mucosa. This dose of ethanol also increased the glutathione content of gastric mucosa (12% in males, 13% in females). Undiluted ethanol decreased glutathione levels in gastric mucosa (22% in males, 11% in females) and increased glutathione peroxide activity in gastric mucosa (14% in males, 9% in females). Undiluted alcohol also produced decreases in the activity of glutathione reductase in stomach (14% in males, 9% in females) and duodenum (16% in males, 12% in females). Undiluted ethanol caused mucosal damage in the body of the stomach in both genders, accompanied by an increase in luminal pH and fluid accumulation in the stomach; these changes were absent in rats given 8% ethanol. The increase in gastrointestinal antioxidant capacity associated with the administration of 8% ethanol may be a factor in the reported cytoprotective effect of lower doses of ethanol.

Effect of curing Helicobacter pylori infection on intragastric pH during treatment with omeprazole

It has been shown that omeprazole treatment produces higher intragastric pH values in Helicobacter pylori positive subjects than in H pylori negative subjects. This study aimed to investigate the effect of curing H pylori on the intragastric pH in both the presence and absence of omeprazole therapy. Twenty four hour intragastric pH recordings were performed before and after a one week course of omeprazole (20 mg once daily) in 18 H pylori positive subjects and were repeated after the infection had been cured. In the absence of omeprazole, the total 24 hour pH values before cure did not differ from those afterwards. During omeprazole treatment the 24 hour pH values were much higher before (median (95% CI) 5.4: 4.3, 6.0), than after cure of infection (3.6: 2.1, 4.4; p < 0.001). The omeprazole induced fall in H+ activity before cure of H pylori did not, however, differ from that afterwards. It is concluded that the apparently greater antisecretory effect of omeprazole during H pylori infection may be a result of the production of acid neutralising compounds by the H pylori. Although a direct interaction between H pylori and omeprazole cannot be excluded, it seems unlikely.

Pathogenic mechanisms

Research is asking how H. pylori causes diseases, and also why the same bacteria produces different conditions in different persons. The process involves bacterial factors and the host's response. Some bacterial factors such as urease are produced by all strains of H. pylori. This enzyme may damage the gastric epithelium by practically releasing ammonia. Other bacterial factors such as vacuolating toxin are only produced by some strains, and these strains are more likely to cause ulcers or cancer. The host's response has been studied by physiologists, immunologists, and histologists, but the separation of systems is artificial. For example, physiologists find that H. pylori stops gastric D-cells from expressing somatostatin normally, which impairs reflex inhibition of acid secretion, but the D-cell malfunction is probably due to inflammatory factors. In H. pylori gastritis, the gastric epithelial cells behave like immunocytes and express class II molecules and cytokines such as interleukin-8. The patient's histological response to H. pylori is quite closely related to the disease outcome. Patients who respond by developing gastric atrophy are more likely to get gastric ulcers or stomach cancer, but patients whose gastric corpus remains healthy tend to secrete more acid and develop duodenal ulcers, particularly if they have gastric metaplasia in their duodenum. Studies of disease mechanisms provide a valuable insight into the development of these common diseases, and may enable us to identify at-risk groups who particularly merit eradication therapy.

Interleukin 1 beta inhibits gastric emptying in rats: mediation through prostaglandin and corticotropin-releasing factor

BACKGROUND/AIMS

Interleukin 1 beta (IL-1 beta) increases the release of corticotropin-releasing factor (CRF) in the brain through prostaglandin pathways. Because central CRF inhibits gastric motor function, the influence and mechanism of action of intracisternal injection of IL-1 beta on gastric emptying were investigated.

METHODS

The 20-minute rate of gastric emptying of a nonnutrient test meal was assessed by the phenol red methylcellulose method 30 minutes after injection of human recombinant IL-1 beta in conscious rats.

RESULTS

IL-1 beta injected intracisternally (0.01-1 ng) or intravenously (0.01-10 ng) dose-dependently decreased gastric emptying by 10%-82% and 0%-89%, respectively. The median effective dose (ED50) was 30-fold lower when IL-1 beta was injected intracisternally (0.1 ng) than intravenously (3 ng). The inhibitory effect of intracisternal IL-1 beta had a rapid onset (within 20 minutes) and was long-lasting (6 hours). Indomethacin (5 mg/kg, intraperitoneally) completely prevented the 61% inhibition induced by intracisternal IL-1 beta (0.1 ng) but had no effect on CRF-induced (600 ng) 72% inhibition of gastric emptying. The intracisternal injection of the IL-1 receptor antagonist (100 ng) or the CRF antagonist [DPhe12, [DPhe12,Nle21,38,C alpha MeLeu37]CRF12-41 (20 micrograms) prevented by 100% and 52%, respectively, the inhibition of gastric emptying evoked by intracisternal IL-1 beta (0.1 ng). The antagonists alone had no effect on basal gastric emptying.

CONCLUSIONS

IL-1 beta acts in the brain to induce a long-lasting inhibition of gastric emptying; IL-1 beta action is mediated through central IL-1 receptors and prostaglandin- and CRF-dependent mechanisms.

Central interleukin-1 beta-induced inhibition of acid secretion in rats: specificity of action

It is well established that IL-1 beta acts in the brain to potently inhibit gastric acid secretion in pylorus-ligated rats. The present study was designed to further investigate the specificity and mechanisms of the centrally mediated antisecretory action of IL-1 beta in conscious rats. Intracerebroventricular injection of IL-1 beta (100 ng) decreased acid secretion in pylorus-ligated rats and inhibited basal and pentagastrin-stimulated acid secretion in rats with chronic gastric fistula. The antisecretory effect of IL-1 beta (100 ng) injected into the lateral ventricle of pylorus ligated rats was completely reversed by prior intracerebroventricular injection of the IL-1 receptor antagonist, IL-1ra, (100 micrograms). Peripheral administration of the somatostatin monoclonal antibody, CURE.S6, did not modify intracisternal IL-1 beta-induced inhibition of acid secretion in pylorus ligated rats. IL-6 and tumor necrosis factor-alpha (100 ng) injected intracisternally did not influence gastric acid secretion in pylorus-ligated rats. These data show that IL-1 beta action in the CNS is mediated through interaction with specific IL-1 receptors and is selective to this cytokine. IL-1 beta antisecretory action can be observed under basal and pentagastrin-stimulated conditions and is independent from somatostatin release in the periphery.