Relationship between nonsteroidal anti-inflammatory drug use, Helicobacter pylori, and gastroduodenal mucosal injury

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Helicobacter pylori and NSAID gastropathy: an ambiguous association

Helicobacter pylori and nonsteroidal anti-inflammatory drugs (NSAIDs) are associated with adverse gastro- intestinal effects ranging from mild dyspepsia to serious complications such as bleeding peptic ulcer. However, controversy persists regarding the interaction between these two well-documented risk factors. Physiology studies reveal that H. pylori infection can protect the upper gastrointestinal tract by increasing prostaglandin levels. In contrast, clinical trial evidence suggests that eradication of H. pylori infection leads to a decreased risk for endoscopic ulcers in people taking NSAIDs. Given the rates of morbidity and mortality and costs attributable to NSAID-associated toxicity, preventive strategies to reduce NSAID side-effects remain important. Until controlled investigations definitively quantify the effect of H. pylori infection and eradication on clinically significant adverse events, a compelling argument can be made for H. pylori testing of chronic NSAID users at increased risk for ulcer disease and eradicating the organism if present.

Helicobacter pylori genotypes, host factors, and gastric mucosal histopathology in peptic ulcer disease

From 183 patients undergoing upper gastrointestinal endoscopy, we used antral and corpus gastric biopsies for bacterial culture and histopathologic examination, blood samples to detect immunoglobulin G antibodies against Helicobacter pylori, and H pylori genomic DNA to analyze cytotoxin-associated gene A (cagA) and vacuolating cytotoxin (vacA) genotypes. As expected, among H pylori biopsy-positive patients, those with duodenal ulcer (DU) (n = 34) had significantly more severe chronic and acute inflammation (P <.001) and epithelial degeneration (P =.004) in the gastric antrum than in the gastric corpus. Each of those 3 parameters and H pylori density were significantly higher in the antrum of patients with DU than in patients with gastric ulcer (GU) or no ulcer. Colonization with vacA s1/cagA-positive strains of H pylori was associated with inflammation and epithelial degeneration in gastric mucosa and increased risk for peptic ulcer disease (PUD), whereas colonization with vacA s2m2/cagA-negative strains was associated with mild gastric histopathology and was not associated with any significant risk for PUD. The predominant H pylori strains in African Americans were vacA s1bm1/cagA-positive, whereas all genotypes were well represented in non-Hispanic-Caucasians. By multivariate analysis, H pylori colonization was significantly associated with DU (Adjusted odds ratio [AdjOR] = 3.2 [1.4-7.2]) and nonsteroidal anti-inflammatory drugs (NSAID) use was inversely associated (AdjOR = 0.3 [0.2-0.7]). NSAID use (AdjOR = 4.3 [1.02-18.5]) and African-American ethnicity (AdjOR = 10.9 [2.6-50]) were significantly associated with GU. Smoking and age were not significantly associated with either DU or GU. These data indicate that DU is associated with an antral-dominant gastritis, and H pylori genotype and NSAID use independently contribute to the pathogenesis of PUD. HUM PATHOL 32:264-273. This is a US Government work. There are no restrictions on its use.

Helicobacter pylori infection--current treatment practice

Helicobacter pylori infection, which is present in 30 - 60% of the population in developed countries and in more than 60% in developing countries, is established to be a major cause of gastritis, peptic ulcer disease and gastric cancer. Eradication therapy has been incorporated into clinical practice over the past 15 years. Treatment regimens include a 2 week bismuth-based triple therapy (a bismuth compound plus metronidazole, tetracycline or amoxycillin), a 1 week proton-pump inhibitor (PPI)-based triple therapy and a 1 week ranitidine bismuth citrate (RBC)-based triple therapy (a PPI or RBC plus any two of the three antibiotics, metronidazole, amoxycillin and clarithromycin). These regimens achieve eradication rates of >> 80%. H. pylori resistance to metronidazole and clarithromycin decreases the clinical efficacy of most regimens, despite the high eradication rates for resistant strains achieved by the RBC-triple therapy in some recent trials. The dose of antibiotics (especially clarithromycin) and the duration of treatment may also influence the eradication rate. Doctors' beliefs impact on clinical practice and, thus, influence the clinical application of eradication therapy. Whereas peptic ulcer disease and primary gastric low-grade B-cell mucosa-associated lymphoid tissue lymphoma (MALToma) have become established as definite indications for eradication therapy, there remain controversies surrounding non-ulcer dyspepsia, gastro-oesophageal reflux disease, atrophic gastritis, intestinal metaplasia, use of non-steroidal anti-inflammatory drugs (NSAIDs) and H. pylori-related extradigestive diseases.

Helicobacter pylori screening for individuals requiring chronic NSAID therapy: a decision analysis

INTRODUCTION

Although it is incontrovertible that Helicobacter pylori causes peptic ulcer disease, controversy persists regarding the impact of H. pylori infection on the incidence of NSAID-related complications and whether H. pylori eradication reduces the rate of adverse events.

METHODS

A symptom-driven decision analytic model was developed to compare the clinical and economic impact of H. pylori screening compared to a strategy of no H. pylori testing for individuals requiring chronic NSAID therapy. In the principal analysis, it was assumed that untreated H. pylori infection increased the ulcer risk by 50% and that successful eradication reduced the risk of adverse events to that of uninfected patients. Patients' ulcer risk and the protective effect of H. pylori eradication were evaluated using sensitivity analysis.

RESULTS

When compared to no H. pylori testing, H. pylori screening led to fewer symptomatic ulcers (no test, 5.4; H. pylori test, 4.6 per 100 patient years) and ulcer complications (no test, 2.6; H. pylori test, 2.3 per 100 patient years) and a higher cost per patient (no test, $435; H. pylori test, $556). The incremental cost attributable to the H. pylori screening strategy to prevent a symptomatic and complicated ulcer was $16,805 and $31,842, respectively. The clinical and cost-effectiveness advantage of H. pylori screening improved as patients' ulcer risk increased or the protective effect of H. pylori eradication was enhanced.

CONCLUSIONS

Based upon the available evidence, H. pylori screening has the potential to reduce NSAID-related adverse events for average-risk patients at an incremental cost. Until controlled investigations definitively quantify the effect of H. pylori eradication on clinically significant NSAID-related adverse events, a compelling argument can be made for H. pylori testing for chronic NSAID users at increased risk of ulcer disease.

The ever-emerging anti-inflammatories. Have there been any real advances?

Gastrointestinal (GI) Adverse Drug Reactions (ADRs) from the NSAIDs are a major cause of morbidity and mortality in arthritic patients taking these drugs. The recent much heralded development of COX-2 selective drugs (celecoxib, rofecoxib), the objective of which has been to spare inhibition of the production of COX-1 derived mucosal protective prostaglandins, may have represented an advance in reducing the risk of serious ADRs--ulcers and bleeding--but does not appear to have reduced the incidence of symptomatic side-effects (nausea, vomiting, epigastric pain/heartburn, abdominal discomfort) which are a major reason for withdrawal from NSAID therapy, especially in the long term. The rationale of COX-2 selectivity from these newer drugs is controversial since there may be pharmacokinetic differences from established carboxylate-NSAIDs that accounts for their apparent lower ulcerogenicity. Moreover, concerns have been recently expressed that as COX-2 is important in ulcer healing, control of prostacyclin production and renal function that they may have adverse reactions from these effects. Indeed, recent reports of enhanced risk of congestive heart failure with rofecoxib are of importance and may relate to impaired prostacyclin production. Moreover, there are other therapeutic strategies that have yielded equally low ulcerogenic NSAIDs (e.g. the prodrug, nabumetone; the established COX-2 inhibitory drug, nimesulide) and even the well-established NSAIDs ibuprofen and diclofenac have relatively low upper GI ulcerogenicity and have been used as benchmark standards in comparative trials of the newer "Oxib" drugs (celecoxib, rofecoxib). Much research interest has centred on the nitric oxide-donating NSAIDs (NO-NSAIDs). The rationale for donating NSAIDs being to counteract the vasoconstriction effects of NSAIDs but this has yet to be fully evaluated. It is not certain that this "antidote" approach will be acceptable as there may also be systemic effects of the nitrobutoxyl--or other NO-donors that may have toxicological consequences. Another strategy is the development of mixed COX-5 lipoxygenase (LOX) inhibitors--the progenitors of which were benoxaprofen and BW-755C. The rationale of reducing the potential for lipoxygenase mediated actions in the stomach (e.g. vasoconstriction, leucocyte accumulation). Clearly, the need to develop newer NSAIDs with lower risks of ulcers and bleeding as well as symptomatic ADRs is still representing a major challenge.

Role of endothelin-converting enzyme-1 in the suppression of constitutive nitric oxide synthase in rat gastric mucosal injury by indomethacin

BACKGROUND

Disturbances in nitric oxide generation and the release of a vasoactive peptide, endothelin-1 (ET-1), are well recognized early events in pathogenesis of NSAID-induced gastropathy. In this study using phosphoramidon, a potent inhibitor of endothelin-converting enzyme-1 (ECE-1), we investigated the influence of ET-1 on the expression of constitutive (cNOS) and inducible nitric oxide synthase (NOS-2) during gastric mucosal injury caused by indomethacin.

METHODS

The experiments were conducted with groups of rats pretreated intragastrically with phosphoramidon (10, 20, and 40 mg/kg) or vehicle, followed 30 min later by an intragastric dose of indomethacin (60 mg/kg). The animals were killed 4 h later and their mucosal tissue subjected to macroscopic damage assessment and biochemical measurements.

RESULTS

In the absence of phosphoramidon, indomethacin caused extensive multiple hemorrhagic lesions of glandular mucosa, accompanied by a 29.9-fold increase in epithelial cell apoptosis, a 13.3-fold increase in NOS-2 and a 5.5-fold decline in the activity of cNOS, while the mucosal expression of ECE-1 activity increased 4-fold and the level of ET-1 showed a 4.8-fold increase. Pretreatment with phosphoramidon produced dose-dependent reduction in the extent of mucosal damage caused by indomethacin, accompanied by a significant recovery in the expression of cNOS, and a marked decline in ECE-1, epithelial cell apoptosis and the mucosal level of ET-1. Phosphoramidon, however, had no effect on the indomethacin-induced increase in the mucosal expression of NOS-2.

CONCLUSIONS

The results suggest that suppression of ET-1 generation counters the mucosal drop in cNOS and the extent of gastric mucosal damage caused by indomethacin, but has no effect on the mucosal responses associated with up-regulation of NOS-2 expression. Hence, only cNOS plays a role in the protection of gastric mucosa against damage by NSAIDs.

Evaluation of omeprazole, lansoprazole, pantoprazole, and rabeprazole in the treatment of acid-related diseases

OBJECTIVE

To review the comparative efficacy and safety of the proton pump inhibitors (PPIs)--omeprazole, lansoprazole, pantoprazole, and rabeprazole--in the management of acid-related diseases.

DATA SOURCES

English-language journal articles retrieved from a MEDLINE search from 1990 to the present using these index terms: proton pump inhibitors, omeprazole, lansoprazole, pantoprazole, rebeprazole, and each of the acid-related diseases.

STUDY SELECTION

Clinical trials and pertinent review articles that discussed the pharmacology, pharmacokinetics, efficacy, and safety of PPIs in the management of acid-related disease.

DATA EXTRACTION

By the authors.

DATA SYNTHESIS

PPIs are substituted benzimidazoles that inhibit gastric acid secretion by covalently binding to the proton pump (H+/K+ ATPase). All undergo extensive hepatic metabolism and conjugation. The four agents differ in their metabolism by and effects on specific hepatic enzymes and thus in their ability to interact with other medications. PPIs are important agents used for eradicating Helicobacter pylori, in treating peptic ulcer disease, gastroesophageal reflux disease, Zollinger-Ellison syndrome, and upper gastrointestinal bleeding, and for preventing acid aspiration. Short-term side effects of the four agents are similar. The long-term safety of pantoprazole and rabeprazole appears similar to that of omeprazole and lansoprazole. Pantoprazole, which is in the final stages of approval for marketing in the United States, will be available in both an oral and injectable formulation.

CONCLUSION

Based on superior efficacy profiles, PPIs are the drugs of choice in managing patients with peptic ulcer disease, gastroesophageal reflux disease, and Zollinger-Ellison syndrome. The decision to select one PPI versus another is most likely to be based on the agents' acquisition costs, formulations, FDA-labeled indications, and overall safety profiles. Intravenous or parenteral pantoprazole may become the preferred antisecretory agent for patients unable to take oral medications (e.g., critically ill patients and those with Zollinger-Ellison syndrome).

Non-steroidal anti-inflammatory drugs inhibit Helicobacter pylori-induced human neutrophil reactive oxygen metabolite production in vitro

BACKGROUND

Helicobacter pylori infection is associated with increased production of gastric mucosal reactive oxygen metabolites which have been implicated in mucosal damage and carcinogenesis. In vitro, neutrophils produce reactive oxygen metabolites following activation by H. pylori. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit neutrophil activation by several factors, e.g. N-formyl-methionyl-leucyl-phenyalanine (f-MLP).

AIM

To examine the effect of NSAIDs on H. pylori-induced reactive oxygen metabolite production by human peripheral blood neutrophils.

METHODS

Neutrophils were stimulated by H. pylori (NCTC 11637) water extract or f-MLP in the presence or absence of NSAIDs. Reactive oxygen metabolite activity was measured by luminol-enhanced chemiluminescence.

RESULTS

H. pylori water extract stimulated a sevenfold increase in chemiluminescence which was inhibited dose-dependently by diclofenac. All six NSAIDs studied (at 10-4 M) significantly inhibited H. pylori-and f-MLP-stimulated neutrophil reactive oxygen metabolite production. Meclofenamic acid and diclofenac had the greatest inhibitory effects on both H. pylori and f-MLP-stimulated neutrophil reactive oxygen metabolite production. The inhibitory effects of other NSAIDs varied with the activation stimulus. NSAIDs did not quench reactive oxygen metabolites generated in a cell-free xanthine:xanthine oxidase assay.

CONCLUSION

Several NSAIDs attenuate H. pylori-induced neutrophil reactive oxygen metabolites production in vitro. This may be relevant to a potential chemopreventative role in gastric cancer and to a possible lack of synergy between H. pylori and NSAID use regarding peptic ulceration.

Helicobacter pylori infection is a protective factor for bleeding gastric ulcers but not for bleeding duodenal ulcers in NSAID users

BACKGROUND

The effect of Helicobacter pylori infection on NSAID-induced gastroduodenal damage is unclear.

AIM

To determine the role of H. pylori and NSAID use in complicated peptic ulcers.

METHODS

A total of 185 consecutive patients with bleeding peptic ulcers and 185 hospitalized matched controls were studied prospectively. Additionally, 75 consecutive uncomplicated peptic ulcers and 75 community controls were also studied. Active H. pylori infection was determined by urea breath test and/or both urease test and histology. Serum CagA and VacA status were determined at random in 135 infected patients and 82 controls. NSAID use was determined by structured data collection.

RESULTS

H. pylori (odds ratio [OR]=5. 98; 2.9-12.3) and NSAID use (OR=5.74; 3.4-9.7) were independent risk factors for duodenal ulcer bleeding, whereas NSAID use was the main risk factor for bleeding gastric ulcers (OR=12.4; 5.5-27.9). Interaction of both factors was associated with reduced risk for bleeding gastric ulcers (OR=0.19; 0.04-0.88) but not for bleeding duodenal ulcers, which showed a similar risk to any one factor alone. This was observed for all types of NSAID use, including low-dose aspirin, and infection by CagA positive strains. H. pylori was the only factor involved in common uncomplicated duodenal ulcers.

CONCLUSION

Interaction of both H. pylori infection and NSAID use decreases the risk of bleeding due to gastric ulcers, but not that due to duodenal ulcers.

Activation of apoptotic caspase-3 and nitric oxide synthase-2 in gastric mucosal injury induced by indomethacin

BACKGROUND

Apoptosis is the process of programmed cell death characterized by a series of distinct biochemical and morphologic changes involving activation of the caspase protease, cascade, which remains under the regulatory control of nitric oxide. In this study we investigated the activity of a key apoptotic protease, caspase-3, and the expression of inducible nitric oxide synthase (NOS-2) associated with gastric epithelial cell apoptosis during indomethacin-induced gastric mucosal injury.

METHODS

The experiments were conducted with groups of rats subjected to intragastric administration of 60 mg/kg indomethacin or the vehicle. After 2 h the animals were killed and their gastric mucosal tissue used for macroscopic assessment, assays of epithelial cell apoptosis, and the measurement of caspase-3 and NOS-2 activities.

RESULTS

Indomethacin caused extensive multiple hemorrhagic lesions accompanied by marked enhancement in epithelial cell apoptosis, a 3.9-fold increase in mucosal expression of caspase-3 activity, and an 11.9-fold induction in NOS-2. Moreover, the mucosal expression of NOS-2 showed a positive correlation with the extent of changes induced in caspase-3 activity.

CONCLUSIONS

The results implicate caspase-3 in the process of indomethacin-induced gastric epithelial cell apoptosis and point towards participation of NOS-2 in the amplification of the cell death signaling cascade, hence contributing to the extent of mucosal injury.