Regulation of RKIP function by Helicobacter pylori in gastric cancer

Helicobacter pylori (H. pylori) is a gram-negative, spiral-shaped bacterium that infects more than half of the world's population and is a major cause of gastric adenocarcinoma. The mechanisms that link H. pylori infection to gastric carcinogenesis are not well understood. In the present study, we report that the Raf-kinase inhibitor protein (RKIP) has a role in the induction of apoptosis by H. pylori in gastric epithelial cells. Western blot and luciferase transcription reporter assays demonstrate that the pathogenicity island of H. pylori rapidly phosphorylates RKIP, which then localizes to the nucleus where it activates its own transcription and induces apoptosis. Forced overexpression of RKIP enhances apoptosis in H. pylori-infected cells, whereas RKIP RNA inhibition suppresses the induction of apoptosis by H. pylori infection. While inducing the phosphorylation of RKIP, H. pylori simultaneously targets non-phosphorylated RKIP for proteasome-mediated degradation. The increase in RKIP transcription and phosphorylation is abrogated by mutating RKIP serine 153 to valine, demonstrating that regulation of RKIP activity by H. pylori is dependent upon RKIP's S153 residue. In addition, H. pylori infection increases the expression of Snail, a transcriptional repressor of RKIP. Our results suggest that H. pylori utilizes a tumor suppressor protein, RKIP, to promote apoptosis in gastric cancer cells.

H. pylori vaccines: why we still don't have any

Helicobacter pylori was appreciated as the major cause of peptic ulcers about 30 years ago and the most significant etiological agent in gastric cancer in the mid-1990s. Since that time, progress in the development of a preventive or therapeutic H. pylori vaccine has been relatively slow. The impediments to rapid advances in the field include a luke-warm enthusiasm among clinicians, research scientists, and public health authorities concerning the need for a vaccine, rudimentary understanding of the correlates of gastric immunity to H. pylori and of gastric mucosal immunology in general, the geographical heterogeneity of the H. pylori genome and insufficient pharmaceutical industry support. Recent enhancements in our understanding of the gastric immune response together with advances in H. pylori genomics now provide the potential to accelerate progress in H. pylori vaccine development. Whether an H. pylori vaccine becomes a reality will likely depend upon our ability to appropriately target the populations at highest risk of the adverse sequelae of infection.

HelicoVax: epitope-based therapeutic Helicobacter pylori vaccination in a mouse model

Helicobacter pylori is the leading cause of gastritis, peptic ulcer disease and gastric adenocarcinoma and lymphoma in humans. Due to the decreasing efficacy of anti-H. pylori antibiotic therapy in clinical practice, there is renewed interest in the development of anti-H. pylori vaccines. In this study an in silico-based approach was utilized to develop a multi-epitope DNA-prime/peptide-boost immunization strategy using informatics tools. The efficacy of this construct was then assessed as a therapeutic vaccine in a mouse model of gastric cancer induced by chronic H. pylori infection. The multi-epitope vaccine administered intranasally induced a broad immune response as determined by interferon-gamma production in ELISpot assays. This was associated with a significant reduction in H. pylori colonization compared with mice immunized with the same vaccine intramuscularly, given an empty plasmid, or given a whole H. pylori lysate intranasally as the immunogen. Total scores of gastric histological changes were not significantly different among the 4 experimental groups. These results suggest that further development of an epitope-based mucosal vaccine may be beneficial in eradicating H. pylori and reducing the burden of the associated gastric diseases in humans.

An Integrated Genomic and Immunoinformatic Approach to H. pylori Vaccine Design

BACKGROUND

One useful application of pattern matching algorithms is identification of major histocompatability complex (MHC) ligands and T-cell epitopes. Peptides that bind to MHC molecules and interact with T cell receptors to stimulate the immune system are critical antigens for protection against infectious pathogens. We describe a genomes-to-vaccine approach to H. pylori vaccine design that takes advantage of immunoinformatics algorithms to rapidly identify T-cell epitope sequences from large genomic datasets.

RESULTS

To design a globally relevant vaccine, we used computational methods to identify a core genome comprised of 676 open reading frames (ORFs) from amongst seven genetically and phenotypically diverse H. pylori strains from around the world. Of the 1,241,153 9-mer sequences encoded by these ORFs, 106,791 were identical amongst all seven genomes and 23,654 scored in the top 5% of predicted HLA ligands for at least one of eight archetypal Class II HLA alleles when evaluated by EpiMatrix. To maximize the number of epitopes that can be assessed experimentally, we used a computational algorithm to increase epitope density in 20-25 amino acid stretches by assembling potentially immunogenic 9-mers to be identically positioned as they are in the native protein antigen. 1,805 immunogenic consensus sequences (ICS) were generated. 79% of selected ICS epitopes bound to a panel of 6 HLA Class II haplotypes, representing >90% of the global human population.

CONCLUSIONS

The breadth of H. pylori genome datasets was computationally assessed to rapidly and carefully determine a core set of genes. Application of immunoinformatics tools to this gene set accurately predicted epitopes with promising properties for T cell-based vaccine development.

Intentional swallowing of foreign bodies is a recurrent and costly problem that rarely causes endoscopy complications

BACKGROUND & AIMS

Guidelines support endoscopic removal of certain gastric foreign bodies (FBs) and all FBs lodged in the esophagus. We studied the poorly understood group of patients who intentionally ingest FBs.

METHODS

Cases of intentional ingestion of FBs (n = 305) were identified, retrospectively, from an electronic endoscopy database and followed. Cases occurred among 33 different patients, who underwent endoscopy from October 1, 2001, to July 31, 2009 (39.0 cases/year); 79% were diagnosed with a psychiatric disorder. Financial cost analysis was performed using hospital billing and cost systems.

RESULTS

Commonly ingested FBs included pens (23.6%), batteries (9.2%), knives (7.2%), and razor blades (6.9%). Most endoscopic procedures were performed under general anesthesia. FBs were commonly retrieved by snares (58.0%), rat-toothed forceps (14.4%), and nets (11.5%), assisted sometimes by use of overtubes (10.8%), and hoods (4.6%). FB extraction was unsuccessful at the initial endoscopy in only 20 cases; 2 cases eventually required surgical extraction. Minor complications occurred in 11 endoscopies. There were no deaths or perforations. The total estimated costs were $2,018,073 ($1,500,627 in hospital costs, $240,640 in physician fees, and $276,806 for security services). Costs were significantly higher for inpatients. Major payers were Medicare (48%) and Medicaid (31%).

CONCLUSIONS

Intentional FB ingestion occurs among a relatively small number of patients with psychiatric disorders and is costly. Endoscopic retrieval is relatively effective and safe, but often requires general anesthesia. These cases utilize significant hospital and fiscal resources. Attention should be focused on preventing these recurrent and costly episodes.

Gastrointestinal neuroendocrine (carcinoid) tumours: current diagnosis and management

Neuroendocrine tumours (NETs) are increasing in both incidence and prevalence and, as a group, are more prevalent than either gastric, pancreatic, oesophageal or hepatobiliary adenocarcinomas, or any two of these cancers combined. Clinical awareness of the protean and intermittent symptoms of NETs (eg, sweating, flushing, diarrhoea, and bronchospasm) is critical for timely diagnosis; however, the classical carcinoid syndrome is relatively uncommon. The most useful diagnostic test for gastrointestinal NETs is measurement of plasma chromogranin A (CgA) levels. Disease extent is assessed by both anatomical imaging, and nuclear imaging with radiolabelled somatostatin analogues. Pathological evaluation comprises tumour-node-metastasis classification, a minimum pathological dataset, CgA and synaptophysin immunostaining, as well as mitotic count or Ki-67 index (a marker of cell proliferation) to define grading. Resection of the primary lesion and as much metastatic disease as possible increases the efficacy of medical therapy. Other management strategies include hepatic embolisation and peptide receptor radionuclide therapy. Patients with tumours expressing somatostatin receptors should be treated with somatostatin analogues. Depending on the tumour grade, other effective agents include cytotoxics, tyrosine kinase inhibitors, and antiangiogenics. The overarching requirement for best management of patients with NETs is to ensure that they have ready access to experienced multidisciplinary clinician groups located within centres of appropriate subspecialty expertise.

Chromogranin A--biological function and clinical utility in neuro endocrine tumor disease

BACKGROUND

Neuroendocrine tumors (NETs) are a form of cancer that differ from other neoplasia in that they synthesize, store, and secrete peptides, e.g., chromogranin A (CgA) and amines. A critical issue is late diagnosis due to failure to identify symptoms or to establish the biochemical diagnosis. We review here the utility of CgA measurement in NETs and describe its biological role and the clinical value of its measurement.

METHODS

Literature review and analysis of the utility of plasma/serum CgA measurements in NETs and other diseases.

RESULTS

CgA is a member of the chromogranin family; its transcription and peptide processing are well characterized, but its precise function remains unknown. Levels are detectable in the circulation but vary substantially (approximately 25%) depending on which assay is used. Serum and plasma measurements are concordant. CgA is elevated in approximately 90% of gut NETs and correlates with tumor burden and recurrence. Highest values are noted in ileal NETs and gastrointestinal NETs associated with multiple endocrine neoplasia type 1. Both functioning and nonfunctioning pancreatic NETs have elevated values. CgA is more frequently elevated in well-differentiated tumors compared to poorly differentiated NETs. Effective treatment is often associated with decrease in CgA levels. Proton pump inhibitors falsely increase CgA, but levels normalize with therapy cessation.

CONCLUSIONS

CgA is currently the best available biomarker for the diagnosis of NETs. It is critical to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy. Measurement of plasma CgA is mandatory for the effective diagnosis and management of NET disease.

Diagnosis and management of non-erosive reflux disease--the Vevey NERD Consensus Group

BACKGROUND/AIMS

Although considerable information exists regarding gastroesophageal reflux disease with erosions, much less is known of non-erosive reflux disease (NERD), the dominant form of reflux disease in the developed world.

METHODS

An expert international group using the modified Delphi technique examined the quality of evidence and established levels of agreement relating to different aspects of NERD. Discussion focused on clinical presentation, assessment of clinical outcome, pathobiological mechanisms, and clinical strategies for diagnosis and management.

RESULTS

Consensus was reached on 85 specific statements. NERD was defined as a condition with reflux symptoms in the absence of mucosal lesions or breaks detected by conventional endoscopy, and without prior effective acid-suppressive therapy. Evidence supporting this diagnosis included: responsiveness to acid suppression therapy, abnormal reflux monitoring or the identification of specific novel endoscopic and histological findings. Functional heartburn was considered a separate entity not related to acid reflux. Proton pump inhibitors are the definitive therapy for NERD, with efficacy best evaluated by validated quality-of-life instruments. Adjunctive antacids or H(2) receptor antagonists are ineffective, surgery seldom indicated.

CONCLUSIONS

Little is known of the pathobiology of NERD. Further elucidation of the mechanisms of mucosal and visceral hypersensitivity is required to improve NERD management.

Non-erosive reflux disease--defining the entity and delineating the management

In the developed world, most patients with gastroesophageal reflux disease (GERD) do not exhibit erosions when examined by standard white light endoscopy. Despite the high prevalence of such non-erosive reflux disease (NERD), relatively little is known of its underlying pathophysiology, hence there is no clear guide to clinical management. To establish areas of agreement or uncertainty in NERD, an international meeting was held in Vevey, Switzerland, in late 2007. The goal was to document current thinking in the areas of clinical presentation, assessment of clinical outcome, pathobiological mechanisms, and define optimal clinical strategies to diagnose and manage NERD. After extensive debates, the modified Delphi technique was utilized to reach a consensus on 85 specific statements. In addition, it was proposed that NERD be defined as 'a subcategory of GERD characterised by troublesome reflux-related symptoms in the absence of esophageal mucosal erosions/breaks at conventional endoscopy and without recent acid suppressive therapy'. Evidence in support of this diagnosis may include responsiveness to acid suppression therapy, abnormal reflux monitoring or the identification of specific novel endoscopic findings. Defining the current state of knowledge in NERD should help improve the elucidation and management of this condition in the future.

Helicobacter pylori virulence factors in gastric carcinogenesis

Helicobacter pylori infection is the most important risk factor in the development of non-cardia gastric adenocarcinoma; host genetic variability and dietary co-factors also modulate risk. Because most H. pylori infections do not cause cancer, H. pylori heterogeneity has been investigated to identify possible virulence factors. The strongest candidates are genes within the cag (cytotoxin-associated antigen) pathogenicity island, including the gene encoding the CagA protein, as well as polymorphic variation in the VacA vacuolating exotoxin and the blood group antigen binding adhesin BabA. Improved understanding of the pathogenesis of H. pylori-associated gastric cancer may improve risk stratification for prevention and therapy.

Helicobacter pylori virulence factors in gastric carcinogenesis

Helicobacter pylori infection is the most important risk factor in the development of non-cardia gastric adenocarcinoma; host genetic variability and dietary co-factors also modulate risk. Because most H. pylori infections do not cause cancer, H. pylori heterogeneity has been investigated to identify possible virulence factors. The strongest candidates are genes within the cag (cytotoxin-associated antigen) pathogenicity island, including the gene encoding the CagA protein, as well as polymorphic variation in the VacA vacuolating exotoxin and the blood group antigen binding adhesin BabA. Improved understanding of the pathogenesis of H. pylori-associated gastric cancer may improve risk stratification for prevention and therapy.

Expression analysis of Barrett's esophagus-associated high-grade dysplasia in laser capture microdissected archival tissue

PURPOSE

Identifying genes differentially expressed in nondysplastic BE (NDBE) from those expressed in high-grade dysplasia (HGD) should be of value in improving our understanding of this transition and may yield new diagnostic and/or prognostic markers. The aim of this study was to determine the differential transcriptome of HGD compared with NDBE through gene microarray analysis of epithelial cells microdissected from archival tissue specimens.

EXPERIMENTAL DESIGN

Laser capture microdissection was used to isolate epithelial cells from adjacent inflammatory and stromal cells. Epithelial mRNA was extracted from areas of NDBE and HGD in matched biopsies from 11 patients. mRNA was reverse transcribed and applied on Affymetrix cDNA microarray chips customized for formalin-exposed tissue. For a subset of these genes, differential gene expression was confirmed by real-time PCR and immunohistochemistry.

RESULTS

There were 131 genes overexpressed by at least 2.5-fold in HGD versus NDBE and 16 genes that were underexpressed by at least 2.5-fold. Among the overexpressed genes are several previously shown to be increased in the neoplastic progression of BE, as well as novel genes such as lipocalin-2, S100A9, matrix metallopeptidase 12, secernin 1, and topoisomerase IIalpha. Genes decreased in dysplastic epithelium include MUC5AC, trefoil factor 1 (TFF1), meprin A, and CD13. Real-time PCR validated the changes in expression in 24 of 28 selected genes. Immunohistochemistry confirmed increased protein expression for topoisomerase IIalpha, S100A9, and lipocalin-2 and decreased expression of TFF1 across the spectrum of BE-associated dysplasia from NDBE through adenocarcinoma.

CONCLUSIONS

This is the first study to identify epithelial genes differentially expressed in HGD versus NDBE in matched patient samples. The genes identified include several previously implicated in the pathogenesis of BE-associated dysplasia and new candidates for further investigation.

Priorities for improving the management of gastroenteropancreatic neuroendocrine tumors

A National Cancer Institute summit meeting on gastroenteropancreatic neuroendocrine and carcinoid tumors was held in September 2007 to present the currently accepted standards of care for patients with these tumors and to identify areas requiring investigation and development. These tumors are clinically and pathologically heterogeneous, present commonly with obscure symptoms that lead to delays in diagnosis of years, and have an incidence in the United States of 2.5 to 5 cases per 100,000. The 5-year survival rates range between 15% and 95%, depending on the site and extent of disease. This report delineates the main conclusions of the meeting, including the best practice diagnosis and treatment strategies for gastropancreatic neuroendocrine tumors, and the identification of clinical and scientific areas that are most in need of attention. The most pressing needs were public and physician education, identification of molecular markers for early diagnosis and therapeutic monitoring, improved imaging modalities and molecular prognostication, development of a standardized pathological classification system, and creation of regional centers of expertise with tumor and laboratory data banks. In addition, adequately validated neuroendocrine tumor models and cell lines should be established to investigate the molecular mechanisms involved in the control of their growth and secretion, and to facilitate the development of specific therapies that should be examined in well-designed multicenter studies of defined patient groups.

Decreased expression of gastrokine 1 and the trefoil factor interacting protein TFIZ1/GKN2 in gastric cancer: influence of tumor histology and relationship to prognosis

PURPOSE

Transcriptional profiling showed decreased expression of gastrokine 1 (GKN1) and the related trefoil factor interacting protein (TFIZ1/GKN2) in Helicobacter pylori infection. Decreased GKN1 and GKN2 mRNA expression has been reported in gastric adenocarcinoma. We have examined GKN1 and GKN2 protein expression in a large gastric cancer series, correlated expression with tumor subtype, and evaluated their utility as prognostic biomarkers.

EXPERIMENTAL DESIGN

GKN1, GKN2, and the trefoil factors TFF1 and TFF3 were examined in tissue microarrays from 155 distal gastric adenocarcinomas. Immunohistochemical expression was correlated with clinical outcome. GKN1 and GKN2 expression was measured by real-time PCR and Western analysis in samples of gastric cancer and adjacent nonneoplastic mucosa.

RESULTS

GKN1 was lost in 78% of diffuse and 42% of intestinal cancers (P < 0.0001, diffuse versus intestinal). GKN2 expression was lost in 85% of diffuse and 54% of intestinal type cancers (P < 0.002). GKN1 and GKN2 down-regulation were confirmed by Western and real-time PCR analysis. Loss of either protein was associated with significantly worse outcome in intestinal-type tumors by univariate analysis; and GKN2 loss remained a predictor of poor outcome in multivariate analysis (P < 0.033). TFF1 was lost in >70%, and TFF3 was expressed in approximately 50% of gastric cancers.

CONCLUSIONS

Loss of GKN1 and GKN2 expression occurs frequently in gastric adenocarcinomas, especially in the diffuse subtype. GKN1 and GKN2 loss are associated with shorter overall survival in the intestinal subtype.

Review article: RNA interference--potential therapeutic applications for the gastroenterologist

BACKGROUND

A new technique of gene regulation, termed RNA interference, has emerged recently. RNA interference utilizes short double-stranded RNA to inhibit selectively gene expression of complementary RNA nucleotide sequences after transcription, but prior to translation. Gastrointestinal and hepatic disorders may be particularly amenable to therapeutic RNA interference intervention because of the relative ease of delivery of drugs to the gastrointestinal tract and liver.

AIM

To examine the published literature for potential clinical uses of RNA interference in gastroenterology and speculate on future therapies for luminal disease.

METHODS

Reports were identified using PubMed and the search term 'RNA interference', focusing on therapeutic uses related to gastrointestinal and liver disease.

RESULTS

Cellular and animal models demonstrate the potential application of short-interfering RNA-based therapies for viral hepatitis and inflammatory bowel disease. With validation of specific targets and better in vivo delivery of short-interfering RNA, RNA interference may represent a new frontier for molecular-targeted therapy in gastroenterology and hepatology.

CONCLUSIONS

Short-interfering RNA provides a novel and specific means to inhibit gene expression. Translation to the clinical arena will require further definition of side-effects, off-target effects and delivery systems. Ultimately, mucosally applied or endoscopically delivered short-interfering RNA could be one of the earliest clinical uses of short-interfering RNA therapy.

Gastroenteropancreatic neuroendocrine tumours

Gastroenteropancreatic (GEP) neuroendocrine tumours (NETs) are fairly rare neoplasms that present many clinical challenges. They secrete peptides and neuroamines that cause distinct clinical syndromes, including carcinoid syndrome. However, many are clinically silent until late presentation with mass effects. Investigation and management should be highly individualised for a patient, taking into consideration the likely natural history of the tumour and general health of the patient. Management strategies include surgery for cure (which is achieved rarely) or for cytoreduction, radiological intervention (by chemoembolisation and radiofrequency ablation), chemotherapy, and somatostatin analogues to control symptoms that result from release of peptides and neuroamines. New biological agents and somatostatin-tagged radionuclides are under investigation. The complexity, heterogeneity, and rarity of GEP NETs have contributed to a paucity of relevant randomised trials and little or no survival increase over the past 30 years. To improve outcome from GEP NETs, a better understanding of their biology is needed, with emphasis on molecular genetics and disease modeling. More-reliable serum markers, better tumour localisation and identification of small lesions, and histological grading systems and classifications with prognostic application are needed. Comparison between treatments is currently very difficult. Progress is unlikely to occur without development of centers of excellence, with dedicated combined clinical teams to coordinate multicentre studies, maintain clinical and tissue databases, and refine molecularly targeted therapeutics.

Helicobacter and gastric malignancies

Over the past year Helicobacter pylori has been confirmed as the most important risk factor for non-cardia gastric adenocarcinomas and gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Eradication therapy has been proven to be beneficial when given prior to the development of intestinal metaplasia, but is less efficacious when administered later. However, the best data from clinical trials indicate that H. pylori eradication alone will have only a moderate effect on gastric cancer incidence worldwide. The mechanisms responsible for H. pylori-associated gastric carcinogenesis continue to be dissected. Accumulating evidence suggests that some H. pylori may be able to invade through the gastric epithelial barrier, though pro-carcinogenic effects may also be related to the complex and evolving pathways of altering signal transduction pathways within gastric epithelial cells that are stimulated by adherence and translocation of H. pylori products through its type IV secretory system. Determinants of the host response to H. pylori infection continue to focus on polymorphisms in genes related to the innate and acquired immune responses, including NOD2, COX-2, and TLR-4. H. pylori eradication is indicated for low-grade gastric B-cell MALT lymphoma and may even provide "cure" in some apparently H. pylori-negative cases. How and why does H. pylori promote lymphomagenesis? Some evidence from human and murine models points to specific chromosomal translocations and host genetic polymorphisms as relating to the outcome of infection. Finally, Helicobacter hepaticus infection has been linked to both intestinal and breast tumorigenesis in susceptible strains of female mice - a provocative and novel finding warranting further investigation.

Targeting Helicobacter pylori in gastric carcinogenesis

Gastric infection by Helicobacter pylori is an important risk factor for the development of gastric cancer. Recent research has identified both bacterial and host factors related to increased gastric cancer risk, including virulence-associated genes located in the cytotoxin-associated gene pathogenicity island and the vacuolating toxin A exotoxin, as well as polymorphisms in key cytokines and cytokine receptors that mediate the host's gastric inflammatory response. Early randomized trials indicate that eradicating H. pylori with antibiotics may prevent gastric cancer, although the effects so far have been modest, and are probably confined to individuals who had not developed preneoplastic lesions at the time of eradication. Targeting H. pylori to prevent gastric cancer may be best achieved through vaccination, better understanding of the molecular pathogenesis of H. pylori-associated carcinogenesis and additional chemopreventive strategies.

Global analysis of the human gastric epithelial transcriptome altered by Helicobacter pylori eradication in vivo

OBJECTIVE

The transcriptional profile of gastric epithelial cell lines cocultured with Helicobacter pylori and the global gene expression of whole gastric mucosa has been described previously. We aimed to overcome limitations of previous studies by determining the effects of H pylori eradication on the transcriptome of purified human gastric epithelium using each patient as their own control.

DESIGN

Laser capture microdissection (LCM) was used to extract mRNA from paraffin-embedded antral epithelium from 10 patients with peptic ulcer disease, before and after H pylori eradication. mRNA was reverse transcribed and applied on to Affymetrix cDNA microarray chips customised for formalin-fixed tissue. Differentially expressed genes were identified and a subset validated by real-time polymerase chain reaction (PCR).

RESULTS

A total of 13 817 transcripts decreased and 9680 increased after H pylori eradication. Applying cut-off criteria (p<0.02, fold-change threshold 2.5) reduced the sample to 98 differentially expressed genes. Genes detected included those previously implicated in H pylori pathophysiology such as interleukin 8, chemokine ligand 3, beta defensin and somatostatin, as well as novel genes such as GDDR (TFIZ1), chemokine receptors 7 and 8, and gastrokine.

CONCLUSIONS

LCM of archival specimens has enabled the identification of gastric epithelial genes whose expression is considerably altered after H pylori eradication. This study has confirmed the presence of genes previously implicated in the pathogenesis of H pylori, as well as highlighted novel candidates for further investigation.

Non-steroidal anti-inflammatory drugs have bacteriostatic and bactericidal activity against Helicobacter pylori

BACKGROUND

Helicobacter pylori infection and non-steroidal anti-inflammatory drugs (NSAIDs) are each associated with gastrointestinal mucosal damage, but the extent and direction of their interactions remain controversial. Therefore, the purpose of the present paper was to examine whether specific NSAIDs inhibit the growth of Helicobacter pylori in vitro.

METHODS

Sodium salicylate, ibuprofen, indomethacin, the selective cyclooxygenase-2 inhibitor NS-398 and two derivatives of sulindac sulfoxide were tested against two laboratory strains of H. pylori, the mouse-adapted Sydney strain, and against seven fresh clinical isolates of Helicobacter pylori. Possible effects on Campylobacter jejuni, Staphyloccoccus aureus, Escherichia coli, Salmonella typhimurium, and Shigella boydii were also examined.

RESULTS

Certain NSAIDs possess antibacterial activity against Helicobacter pylori at therapeutically achievable doses; an effect that appears to be independent of cyclooxygenase enzymes inhibition. For Helicobacter pylori, >90% growth inhibition and bactericidal activity were observed consistently for sulindac sulfide at < or =70 microg/mL and sulindac sulfone at < or =175 microg/mL. The minimal inhibitory concentration against Helicobacter pylori was 125 microg/mL for ibuprofen, 100 microg/mL for indomethacin and 300 microg/mL for NS-398 but much higher concentration of sodium salicylate (4000 microg/mL) and sulindac sulfoxide (> or =1250 microg/mL) were required to inhibit the growth of Helicobacter pylori.

CONCLUSIONS

The decreased prevalence of Helicobacter pylori in specimens from some NSAID users and the chemopreventive effects of NSAIDs in gastric cancer may be related to inhibition of Helicobacter pylori growth.

Engineering mucosal RNA interference in vivo

Mucosal surfaces serve as a gateway to disease. Here, we demonstrate that RNA interference can be used to manipulate mucosal gene expression in vivo. Using a murine model, we show that direct application of liposome-complexed siRNA mediates gene-specific silencing in cervicovaginal and rectal mucosa. A single vaginal or rectal administration of siRNA targeting hematopoietic or somatic cell gene products reduced corresponding mRNA levels by up to 90%. Using a murine model of inflammatory bowel disease, we found that the rectal application of siRNA targeting TNF-alpha led to relative mucosal resistance to experimental colitis. Liposomal siRNA formulations proved nontoxic, did not elicit a nonspecific interferon response, and provide a means for genetic engineering of mucosal surfaces in vivo.