Helicobacter pylori and gastric acid: biological and therapeutic implications

Pathogenicity and virulence of Helicobacter pylori: A paradigm of chronic infection

Infection with Helicobacter pylori is one of the most common infections of mankind. Infection typically occurs in childhood and persists for the lifetime of the host unless eradicated with antimicrobials. The organism colonizes the stomach and causes gastritis. Most infected individuals are asymptomatic, but infection also causes gastric and duodenal ulceration, and gastric cancer. H. pylori possesses an arsenal of virulence factors, including a potent urease enzyme for protection from acid, flagella that mediate motility, an abundance of outer membrane proteins that can mediate attachment, several immunomodulatory proteins, and an ability to adapt to specific conditions in individual human stomachs. The presence of a type 4 secretion system that injects effector molecules into gastric cells and subverts host cell signalling is associated with virulence. In this review we discuss the interplay of H. pylori colonization and virulence factors with host and environmental factors to determine disease outcome in infected individuals.

Causal effect of gut microbiota on Gastroduodenal ulcer: a two-sample Mendelian randomization study

Background

Gastroduodenal ulcers are associated with Helicobacter pylori infection and the use of nonsteroidal anti-inflammatory drugs (NSAIDs). However, the causal relationship between gastroduodenal ulcers and gut microbiota, especially specific gut microbiota, remains unclear.

Methods

We conducted an analysis of published data on the gut microbiota and Gastroduodenal ulcer using genome-wide association studies (GWAS). Two-sample Mendelian randomization (MR) analysis was performed to determine the causal relationship between gut microbiota and Gastroduodenal ulcer. Sensitivity, heterogeneity, and pleiotropy analyses were conducted to confirm the accuracy of the research findings.

Results

Our study showed that the abundance of Enterobacteriaceae, Butyricicoccus, Candidatus Soleaferrea, Lachnospiraceae NC2004 group, Peptococcus, and Enterobacteriales was negatively correlated with the risk of Gastroduodenal ulcer. Conversely, the abundance of Streptococcaceae, Lachnospiraceae UCG010, Marvinbryantia, Roseburia, Streptococcus, Mollicutes RF9, and NB1n was positively correlated with the risk of Gastroduodenal ulcer. MR analysis revealed causal relationships between 13 bacterial genera and Gastroduodenal ulcer.

Conclusion

This study represents a groundbreaking endeavor by furnishing preliminary evidence regarding the potentially advantageous or detrimental causal link between the gut microbiota and Gastroduodenal ulcer, employing Mendelian Randomization (MR) analysis for the first time. These discoveries have the potential to yield fresh perspectives on the prevention and therapeutic approaches concerning Gastroduodenal ulcer, with a specific focus on the modulation of the gut microbiota.

Factors associated with treatment failure, and possible applications of probiotic bacteria in the arsenal against Helicobacter pylori

INTRODUCTION

Helicobacter pylori is a widespread helical Gram-negative bacterium, which causes a variety of stomach disorders, such as peptic ulcer, chronic atrophic gastritis, and gastric cancer. This microbe frequently colonizes the mucosal layer of the human stomach and survives in the inhospitable microenvironment, by adapting to this hostile milieu.

AREAS COVERED

In this extensive review, we describe conventional antibiotic treatment regimens used against H. pylori including, empirical, tailored, and salvage therapies. Then, we present state-of-the-art information about reasons for treatment failure against H. pylori. Afterward, the latest advances in the use of probiotic bacteria against H. pylori infection are discussed. Finally, we propose a polymeric bio-platform to provide efficient delivery of probiotics for H. pylori infection.

EXPERT OPINION

For effective probiotic delivery systems, it is necessary to avoid the early release of probiotics at the acidic stomach pH, to protect them against enzymes and antimicrobials, and precisely target H. pylori bacteria which have colonized the antrum area of the stomach (basic pH).

Changes in Acidity Levels in the Gastric Tube After Esophagectomy for Esophageal Cancer

Reflux esophagitis and gastric tube ulcer sometimes cause severe clinical problems in patients undergoing esophagectomy with gastric tube reconstruction. We previously reported that acidity in the gastric tube was decreased for 1 year after esophagectomy, and that lower acidity levels were associated with Helicobacter pylori (H. pylori) infection. However, the long-term changes in gastric acidity remain unknown. We aimed to investigate the long-term changes in gastric acidity after surgery. Eighty-nine patients who underwent esophagectomy with gastric tube reconstruction for esophageal cancer were analyzed. They underwent 24-hour pH monitoring, serum gastrin measurement, and H. pylori infection examination before surgery, at 1 month, 1 year, and 2 years after surgery. The gastric acidity at 1 month and 1 year after surgery was significantly lower than that before surgery (p=0.003, p=0.003). However, there was no difference in gastric acidity before and 2 years after surgery. The gas tric acidity in H. pylori-infected patients was significantly lower in comparison to non-infected patients at each time point (p=0.0003, p<0.0001, p<0.0001, p<0.0001, respectively). In H. pylori-infected patients, gastric acid ity was decreased for 1 year after surgery, and recovered within 2 years after surgery. However, no significant differences were observed in the acidity levels of non-infected patients during the 2-year follow-up period. The serum gastrin level increased after esophagectomy. The acidity levels in the gastric tube recovered within 2 years after surgery. Periodic endoscopy examination is recommended for early detection of acid-related disease, such as reflux esophagitis or gastric tube ulcer, after esophagectomy with gastric tube reconstruction.

Trace element levels in serum and gastric mucosa in patients with Helicobacter pylori positive and negative gastritis

BACKGROUND

Most trace elements are inhibited by Helicobacter pylori-infection, and variations in specific element levels are linked to the development of stomach cancer. This is the first study to show the relationship between serum and tissue concentrations of twenty-five trace elements and H. pylori infection status. This study purposed to define serum and tissue trace element levels of 25 healthy individuals with Helicobacter pylori-positive gastritis and Helicobacter pylori-negative gastritis and to reveal their relationship with the disease.

METHODS

Study groups consisted of sixty-two patients with Helicobacter pylori-positive, thirty-seven patients with Helicobacter pylori-negative, and thirty healthy individuals. Serum and tissue concentrations of twenty-five elements (aluminum, boron, arsenic, barium, calcium, beryllium, copper, cadmium, iron, chromium, mercury, lithium, potassium, magnesium, sodium, manganese, nickel, phosphorus, lead, scandium, strontium, selenium, tellurium, titanium, zinc) were defined by inductively coupled plasma optical emission spectrometry.

RESULTS

Except for copper, lithium, and strontium elements in serum samples, other trace elements differed significantly between the groups (p < 0.05). The serum chromium (p = 0.002), mercury (p = 0.001), boron (p < 0.001), and cadmium (p < 0.001) levels of H. pylori-negative gastritis and H. pylori-positive gastritis participants were significantly different, and their serum concentrations were less than 0.5 µ/l. Boron, barium, beryllium, chromium, lithium, phosphorus and strontium elements in tissue samples did not differ significantly between the groups (p > 0.05). Manganese, nickel, tellurium and titanium elements were not detected in tissue and serum samples. The mean concentrations of calcium, beryllium, chromium, iron, potassium, lithium, magnesium, scandium, and selenium were higher in the tissues of patients with H. pylori gastritis compared to healthy control tissues. Also, cadmium could not be detected in tissue samples. There was a significant difference between H. pylori-infected tissue and serum chromium levels (p = 0.001), with lower levels detected in tissue samples.

CONCLUSION

This is the first study that we are knowledgeable of that reports the concentrations of twenty five elements in both serum and tissue samples, as well as the relationship between trace elements and Helicobacter pylori-infection status. Dietary adjustment is indicated as an adjunct to medical therapy to stabilize trace elements because Helicobacter pylori bacteria cause inflammation and impair element absorption in gastritis patients. We also think that this study will shed light on studies on the relationship between Helicobacter pylori-trace elements and serum-tissue/healthy serum-tissue trace element levels of patients with Helicobacter pylori gastritis.

Potential factors of Helicobacter pylori resistance to clarithromycin

OBJECTIVES

A comparative dissolution kinetics test (CDKT) and bioequivalence studies of generic proton pump inhibitors (PPIs) do not model pharmacological acid suppression (PAS) and pathological duodenogastric reflux (PDGR). This study aimed to model them in CDKT to assess drugs stability and potential pantoprazole-clarithromycin interactions.

METHODS

In CDKT, PDGR (dissolution medium pH 7.00 ± 0.05, preexposure at pH 1.20 ± 0.05) and PAS (pH 4.00 ± 0.05) were modelled for original pantoprazole (OP) and its generics (GP1-4). In CDKT with high-performance liquid chromatography, dissolution gastric medium in adequate (pH 4.00 ± 0.05) and inadequate (pH 1.20 ± 0.05) PAS were modelled for original clarithromycin (OC) and its generics (GC1-4).

RESULTS

After exposure in pH 7.00 ± 0.05, pantoprazole was released from GP1 within 10 min in the amount of 68.8%. In рН 4.00 ± 0.05, 83.0% and 81.5% of pantoprazole were released from GP1 and GP4. When OP, GP2 and GP3 were placed in pH 7.00 ± 0.05, pantoprazole was released in amount: 99.4%, 88.0% and 98.2%. Clarithromycin releasing from OC, GC1, GC2, GC3, GC4 in pH 4.00 ± 0.05 was 93.5%, 91.6%, 92.9%, 79.4% and 83.0%. In pH 1.20 ± 0.05: 9.7%, 6.7%, 8.5%, 33.3%, 28.8%.

CONCLUSIONS

Destruction of enteric coats of some local pantoprazole generics in CDKT-models might be a potential factor for inadequate therapy.

Protective Effects of Silibinin on Helicobacter pylori-induced Gastritis: NF-κB and STAT3 as Potential Targets

More than half of the world's populations are considered to be infected by Helicobacter pylori. It causes a chronic inflammation of the stomach, which is implicated in the pathogenesis of gastric ulcer and cancer. Silibinin, a polyphenolic flavonoid derived from milk thistle, has been known for its hepatoprotective effects, and recent studies have revealed its chemopreventive potential. In the present study, we examined the anti-inflammatory effects of silibinin in human gastric cancer MKN-1 cells and in the stomach of C57BL/6 mice infected by H. pylori. Pretreatment with silibinin attenuated the up-regulation of COX-2 and inducible nitric oxide synthase (iNOS) in H. pylori-infected MKN-1 cells and mouse stomach. In addition, the elevated translocation and DNA binding of NF-κB and STAT3 induced by H. pylori infection were inhibited by silibinin treatment. Moreover, H. pylori infection in combination with high salt diet resulted in dysplasia and hyperplasia in mouse stomach, and these pathological manifestations were substantially mitigated by silibinin administration. Taken together, these findings suggest that silibinin exerts anti-inflammatory effects against H. pylori infection through suppression of NF-κB and STAT3 and subsequently, expression of COX-2 and iNOS.

Giardia lamblia and Helicobacter pylori coinfection in gastrointestinal biopsies: A retrospective single-center analysis from Switzerland

BACKGROUND

The protozoan Giardia lamblia (GL) and the bacterium Helicobacter pylori (HP) are common causes of gastrointestinal disease. Coinfection is common and has been reported in studies from Africa, Europe, North America and Asia, but data for Switzerland are scarce.

AIM

To investigate GL and HP prevalence and coinfection rate in gastrointestinal biopsies from the Zurich area of Switzerland.

METHODS

Cases were retrieved from the laboratory information system (Medica Institute of Clinical Pathology, Zurich, Switzerland). Histological slides of cases with GL were reviewed, as were the concurrent gastric biopsies, where available.

RESULTS

Between January 1, 2013 and December 31, 2020, GL was found in 88 (0.14%) of 62,402 patients with a small intestine biopsy and HP in 10,668 (15.5%) of 68,961 patients with a gastric biopsy. 74/88 (84.1%) of patients with GL had unremarkable small intestine biopsies, 13/88 (14.8%) had increased intraepithelial lymphocytes, 5/88 (5.7%) showed villous atrophy and 2/88 (2.3%) acute inflammation. 71/88 patients (80.7%) with GL had an available gastric biopsy, of which 12/71 (16.9%) were unremarkable, 28/71 (39.4%) had HP-associated gastritis, 11/71 (15.5%) showed reactive gastropathy and 1/71 (1.4%) had autoimmune gastritis.

CONCLUSION

Coinfection with HP is common in patients with GL in gastrointestinal biopsies from the Zurich area of Switzerland. Therefore, gastroenterologists should consider sampling the stomach when GL is suspected for evaluation of possible concurrent HP-associated gastritis. Likewise, pathologists should scrutinize any small intestine biopsy for the presence of GL when HP-associated gastritis is seen, and vice versa.

Molecular association of FtsZ with the intrabacterial nanotransportation system for urease in Helicobacter pylori

Helicobacter pylori possesses intrabacterial nanotransportation system (ibNoTS) for transporting CagA, VacA, and urease within the bacterial cytoplasm, which is controlled by the extrabacterial environment. The route of ibNoTS for CagA is reported to be associated with the MreB filament, whereas the route of ibNoTS for urease is not yet known. In this study, we demonstrated by immunoelectron microscopy that urease along the route of ibNoTS localizes closely with the FtsZ filament in the bacterium. Supporting this, we found by enzyme immunoassay and co-immunoprecipitation analysis that urease interacted with FtsZ. These findings indicate that urease along the route of ibNoTS is closely associated with the FtsZ filament. Since these phenomena were not observed in ibNoTS for CagA, the route of ibNoTS for CagA is different from that of ibNoTS for urease. We propose that the route of ibNoTS for urease is associated with the FtsZ filament in H. pylori.

Lipid and Protein Oxidation during in Vitro Gastrointestinal Digestion of Pork under Helicobacter pylori Gastritis Conditions

Helicobacter pylori gastritis affects gastric pH and concentrations of ascorbic acid, hydrogen peroxide, hypochlorite, ammonia and urea, pepsin, and mucin. First, the separate effects of each of these altered factors on oxidation of pork were investigated during in vitro gastrointestinal digestion. Lipid and protein oxidation increased (range 23-48%) in duodenal digests of pork previously exposed to elevated (6.1) versus normal acidic stomach pH (2.3 to 3.5) conditions. Salivary nitrite reduced the formation of lipid and protein oxidation products (range 14-20%) under normal acidic but not elevated stomach pH conditions. Higher amounts of hydrogen peroxide and lower amounts of ascorbic acid decreased concentrations of lipid oxidation products in duodenal pork digests, whereas ammonia slightly stimulated protein oxidation during digestion. Second, two H. pylori gastritis-duodenal digestion models were installed using a set of altered compound concentrations at normal acidic or elevated stomach pH. The elevated pH-gastritis-duodenal digestion model increased pork protein oxidation compared with the normal pH-gastritis and the normal digestion model (14.3 ± 2.1 vs 8.2 ± 1.0 nmol DNPH/mg protein, P < 0.001). Compared with the other models, protein oxidation was also increased when nitrite-cured pork was exposed to the elevated pH-gastritis-duodenal digestion model (10.8 ± 1.4 vs 5.9 ± 0.8 nmol DNPH/mg protein, P < 0.001), but no significant effect of the model was observed when the pork was seasoned with herbs. Lipid oxidation was not or was marginally affected by the installed model.

Helicobacter pylori infection is associated with favorable outcome in advanced gastric cancer patients treated with S-1 adjuvant chemotherapy

BACKGROUND AND OBJECTIVES

Limited information exists regarding beneficial effects of Helicobacter pylori. To examine the effect in advanced gastric cancer, we compared survival for patients treated with surgery-only or adjuvant chemotherapy on the basis of H. pylori infection status.

METHODS

A cohort of 491 patients who underwent R0 resection for locally advanced gastric cancer between 2000 and 2009 at 12 institutions in northern Japan was included. H. pylori infection status, was assessed from paraffin-embedded formalin-fixed samples. Overall survival (OS) and disease-free survival (DFS) in surgery-only (Surgery) and adjuvant chemotherapy (S-1) groups were analyzed. A propensity score matching was employed to correct for confounding factors by indication.

RESULTS

H. pylori infection was positive in 175 patients and negative in 316 patients. H. pylori-positive patients showed significantly better survival than H. pylori-negative patients in both OS (hazard ratio [HR] 0.593, 95% confidence interval [CI] 0.417-0.843; P = 0.003]) and DFS (HR 0.679, 95%CI 0.492-0.937; P = 0.018). Propensity score matching further confirmed that S-1 was virtually only effective when tumors were H. pylori-positive.

CONCLUSIONS

The favorable outcome of H. pylori-positive patients implies that the host immune system is modulated by H. pylori enhancing the chemotherapeutic efficacy.

Ethnopharmacological and toxicological review of Cydonia oblonga M

Abstract Cydonia oblonga M. is a medicinal plant of family Rosaceae which is used to prevent or treat several ailments such as cancer, diabetes, hepatitis, ulcer, respiratory, and urinary infections, etc. Cydonia oblonga commonly known as quince is rich in useful secondary metabolites such as phenolics, steroids, flavonoids, terpenoids, tannins, organic acids, and glycosides. It shows a wide range of pharmacological effects like antioxidant, antibacterial, antifungal, anti-inflammatory, hepatoprotective, cardiovascular, antidepressant, hypolipidemic, diuretic, etc. The polysaccharide mucus, glucuronoxylane located in the seeds of the quince, is used in the dermatology, for the production of wound patches. The aim of this paper focuses on detailed research on the value of phytochemicals, as pharmacological and attributes of phytomedicine herbs. Keywords: Cydonia oblonga, phytomedicine, pharmacological attributes, folk medicinal uses, quince

Comparison of efficacy and pharmacoeconomics of two Helicobacter pylori eradication regimens in peptic ulcer disease

Background

Helicobacter pylori, the cause of most peptic ulcer diseases, infects approximately 50% of the population worldwide. Indian data on cost and effectiveness of the standard first-line therapies for H. pylori eradication are scarce. Thus, the present study was aimed at comparing the cost and efficacy of two standard first-line therapies: Regimen I comprising pantoprazole (40 mg) plus amoxicillin (750 mg) plus clarithromycin (500 mg) (PAC) and Regimen II comprising rabeprazole (20 mg) plus amoxicillin (625 mg) plus metronidazole (200 mg) (RAM).

Methodology

This prospective, observational, bottom-up study collected demographic, economic, diagnostic, and therapeutic data from 60 H. pylori-positive patients. The study was carried out for 6 months in the Gastroenterology Department of a Tertiary Care Hospital in Hyderabad, Telangana, India.

Results

Health-care system perspective was used to account for direct costs. Average cost per patient for complete H. pylori eradication was Rs. 10,221 and Rs. 8568 for Regimen I and Regimen II, respectively. Inpatient cost was considerably higher than the outpatient cost. Diagnostic costs ranked first in direct costs, followed by hospitalization costs, medication costs, and finally, physician's office visit cost. Individual patient's costs difference between two regimens was found to be statistically significant. Overall, Regimen I proved to be more efficacious than Regimen II, but Regimen II proved to be more cost-effective than Regimen I. Furthermore, incremental cost-effectiveness analysis revealed additional cost of Rs. 127 per patient if the patient was treated with Regimen I instead of Regimen II.

Conclusion

Our study showed that Regimen II (RAM) was more cost-effective than Regimen I (PAC), but PAC achieved faster H. pylori eradication than RAM. We assume that this study provides local clinical data as to which regimen may be useful in a particular patient. National Level Clinical Trials are required to further ascertain this conclusion.

Helicobacter pylori Infection and Inflammation: Implication for the Pathophysiology of Diabetes and Coronary Heart Disease in Asian Indians

Asian Indians living in the Indian subcontinent or abroad experience high rate of coronary heart disease (CHD) and type 2 diabetes mellitus (T2DM). Asian Indians are also known to suffer from various infections, particularly during their childhood. One such chronic infection is with Helicobacter pylori (H. pylori). Since H. pylori with its specific virulence factor cytotoxin-associated gene A (cagA) has been suggested to be associated with CHD, a role of this H. pylori infection was investigated in the pathogenesis of CHD in Asian Indians living in Bangladesh. H. pylori (CagA) infected subjects with CHD (HP+ve cases, n=21), and without CHD (HP+ve controls, n=20), and non-infected without CHD (HP-ve normal controls, n=21) were included in this study. Thromboxane (TXB), an index of platelet activation, was found to be significantly higher in the HP+ve cases (p=0.05), but not in the HP+ve controls (p=0.88) when compared with HP-ve controls. Analyses of lipid profiles revealed that while triglycerides, total cholesterol and LDL did not show any significant changes, HDL was significantly lower in both the HP+ve cases (p=0.0003) and controls (p=0.005). The mean fasting glucose level in the HP+ve cases was markedly increased (p>0.0001), while it was intermediate in the HP+ve controls, and lowest in the HP-ve controls. HOMA-IR values, a measure of insulin resistance, did not reflect any substantial differences between the HP+ve and HP-ve controls, but they were highly significantly different between the HP+ve cases and HP-ve controls. HOMA-B, indicating insulin secretory dysfunction (ISD), was significantly higher in both the HP+ve groups when compared with the normal controls. The data indicate that H. pylori infection is associated with impaired insulin secretion, and that a component of insulin resistance that occurs independent of H. pylori can then lead to a worsening of glucose tolerance and the development of CHD. This is the first demonstration to our knowledge that H. pylori (CagA) infection is associated with insulin secretory dysfunction in human subjects. Since many Asian Indians contract various other chronic and acute infections, it is important to investigate the role of H. pylori and other infectious agents in the pathogenesis of T2DM and CHD.

Cydonia oblonga M., A Medicinal Plant Rich in Phytonutrients for Pharmaceuticals

Cydonia oblonga M. is a medicinal plant of family Rosaceae which is used to prevent or treat several ailments such as cancer, diabetes, hepatitis, ulcer, respiratory, and urinary infections, etc. Cydonia oblonga commonly known as Quince is rich in useful secondary metabolites such as phenolics, steroids, flavonoids, terpenoids, tannins, sugars, organic acids, and glycosides. A wide range of pharmacological activities like antioxidant, antibacterial, antifungal, anti-inflammatory, hepatoprotective, cardiovascular, antidepressant, antidiarrheal, hypolipidemic, diuretic, and hypoglycemic have been ascribed to various parts of C. oblonga. The polysaccharide mucilage, glucuronoxylan extruded from seeds of C. oblonga is used in dermal patches to heal wounds. This review focuses on detailed investigations of high-valued phytochemicals as well as pharmacological and phytomedicinal attributes of the plant.

Gastric Hypersecretory States: Investigation and Management

Hypersecretory conditions affecting the stomach account for significant morbidity and mortality manifested in some cases with peptic ulcer, gastrointestinal hemorrhage, and/or gastroesophageal reflux disease (GERD). The diagnosis of gastric acid hypersecretory states can be challenging and relies on the use of quantitative assays to measure gastric acid secretion and serum gastrin. The most common etiology for hypergastrinemia is the use of potent gastric acid inhibitors such as the proton pump inhibitors. The differential diagnosis of this condition is of critical importance, and will dictate management decisions. Conditions such as atrophic gastritis are relatively benign and can lead to hypergastrinemia without the presence of gastric acid hypersecretion. Zollinger-Ellison syndrome, on the other hand, causes hypergastrinemia with profound gastric acid hypersecretion [1]. More common causes of hypergastrinemia include gastric outlet obstruction, ileus, and chronic renal failure [2]. In most cases, proton pump inhibitors will be used to manage these conditions. In some instances, surgical therapy may be required. This chapter will review the important clinical causes of gastric acid hypersecretion and provide insights to the best medical management options to better care for patients with these disorders.

Route of intrabacterial nanotransportation system for CagA in Helicobacter pylori

Helicobacter pylori (H. pylori) possesses an intrabacterial nanotransportation system (ibNoTS) for transporting CagA and urease within the bacterial cytoplasm; this system is controlled by the extrabacterial environment. The transportation routes of the system have not yet been studied in detail. In this study, we demonstrated by immunoelectron microscopy that CagA localizes closely with the MreB filament in the bacterium, and MreB polymerization inhibitor A22 obstructs ibNoTS for CagA. These findings indicate that the route of ibNoTS for CagA is closely associated with the MreB filament. Because these phenomena were not observed in ibNoTS for urease, the route of ibNoTS for CagA is different from that of ibNoTS for urease as previously suggested. We propose that the route of ibNoTS for CagA is associated with the MreB filament in H. pylori.

The DNA-binding protein HU has a regulatory role in the acid stress response mechanism in Helicobacter pylori

BACKGROUND

Bacterial genomes are compacted by association with histone-like proteins to form a complex known as bacterial chromatin. The histone-like protein HU is capable of binding and bending the DNA molecule, a function related to compaction, protection, and regulation of gene expression. In Helicobacter pylori, HU is the only histone-like protein described so far. Proteomic analysis from our laboratory showed that this protein is overexpressed under acidic stress.

MATERIALS AND METHODS

We used a purified recombinant wild-type protein and two mutant proteins with the amino acid substitutions K3A/S27D and K62R/V63N/P64A to characterize the function of the N-terminal domain and the flexible arm of HU.

RESULTS

In vitro assays for DNA protection, bending, and compaction were performed. We also designed a H. pylori hup::cat mutant strain to study the role of HU in the acid stress response. HUwt protein binds DNA and promotes its bending and compaction. Compared with the wild-type protein, both mutant proteins have less affinity for DNA and an impaired bending and compaction ability. By using qRT-PCR, we confirmed overexpression of two genes related to acid stress response (ureA and speA). Such overexpression was abolished in the hup::cat strain, which shows an acid-sensitive phenotype.

CONCLUSIONS

Altogether, we have shown that HUwt -DNA complex formation is favored under acidic pH and that the complex protects DNA from endonucleolytic cleavage and oxidative stress damage. We also showed that the amino-terminal domain of HU is relevant to DNA-protein complex formation and that the flexible arm of HU is involved in the bending and compaction activities of HU.

The effect of Helicobacter pylori eradication on the levels of essential trace elements

Objective. This study was designed to compare the effect of Helicobacter pylori (H. pylori) infection treatment on serum zinc, copper, and selenium levels. Patients and Methods. We measured the serum zinc, copper, and selenium levels in H. pylori-positive and H. pylori-negative patients. We also evaluated the serum levels of these trace elements after H. pylori eradication. These serum copper, zinc, and selenium levels were determined by inductively coupled plasma mass spectrometry. Results. Sixty-three H. pylori-positive patients and thirty H. pylori-negative patients were studied. Serum copper, zinc, and selenium levels had no significant difference between H. pylori-positive and H. pylori-negative groups. There were 49 patients with successful H. pylori eradication. The serum selenium levels were lower after successful H. pylori eradication, but not significantly (P = 0.06). There were 14 patients with failed H. pylori eradication. In this failed group, the serum selenium level after H. pylori eradication therapy was significantly lower than that before H. pylori eradication therapy (P < 0.05). The serum zinc and copper levels had no significant difference between before and after H. pylori eradication therapies. Conclusion. H pylori eradication regimen appears to influence the serum selenium concentration (IRB number: KMUH-IRB-20120327).

The effect of Helicobacter pylori eradication on insulin resistance and HbA1c level in people with normal glucose levels: a prospective study

BACKGROUND AND AIM

Helicobacter pylori (H. pylori) infection is reported to be associated with various extragastrointestinal conditions such as insulin resistance, diabetes mellitus and metabolic syndrome. These conditions are attributed to systemic inflammation, leptin or ghrelin changes due to H. pylori infection. Therefore, increasing trends in the management of H. pylori infection are ordered to maintain glycemic control. In this study, we evaluated the effect of H. pylori eradication on insulin resistance in patients with normal blood glucose concentrations.

METHOD

A total of 370 patients with successful eradication were included in the study. Patients with H. pylori were given triple eradication treatment. All patients with H. pylori infection were tested for fasting glucose, fasting insulin, glicated hemoglobin (HbA1c) at baseline and 6 months after eradication treatment. Also, insulin resistance was calculated using the homeostatic model assessment of insulin resistance (HOMA-IR). Body mass index was also determined as a metabolic syndrome criteria effecting insulin resistance.

RESULTS

There were significant differences in fasting glucose, fasting insulin, HbA1c, and HOMA-IR values between before treatment and after treatment(P <0.04, <0.01, <0.01, <0.01). The favorable effect of eradication was more significant in patients with BMI≥25 mg/m(2)(P<0.05).

CONCLUSION

Eradication treatment has beneficial effects on insulin resistance in patients with normal glucose concentrations.

Associations of Helicobacter pylori infection and cytotoxin-associated gene A status with autoimmune thyroid diseases: a meta-analysis

BACKGROUND

Helicobacter pylori infection is reportedly associated with extradigestive diseases such as immune thrombocytopenic purpura and coronary heart disease. The risk factors for autoimmune thyroid diseases (ATDs) remain largely unknown, and whether H. pylori infection is associated with ATDs is still controversial. The aim of this meta-analysis was to determine the association between H. pylori infection and ATDs.

METHODS

Studies comparing the prevalence rate of H. pylori infection in patients with ATDs and healthy controls, published in English, were identified through a systematic search in MEDLINE and EMBAS up to June 2012. Serological or nonserological tests were used to confirm H. pylori infection and the presence of cytotoxin-associated gene A (CagA) antigens. The odds ratios (OR) and associated 95% confidence intervals [CI] were obtained.

RESULTS

Seven studies involving a total of 862 patients met the inclusion criteria and thus were included in our meta-analysis. Overall, H. pylori infection was associated with ATDs (OR 1.92 [CI 1.41-2.61]); the association was significant for Graves' disease (OR 4.35 [CI 2.48-7.64]) but not for Hashimoto's thyroiditis (OR 1.45 [CI 0.92-2.26], p=0.11). No association was observed in the subanalysis of studies using only enzyme-linked immunosorbent assay to detect H. pylori infection (OR 1.38 [CI 0.86-2.19], p=0.18). Five of the seven articles reported the association of CagA seroprevalence and ATDs. CagA seropositivity significantly increased the risk for ATDs by 2.24-fold [CI 1.06-4.75].

CONCLUSIONS

Both the prevalence of H. pylori infection and the seroprevalence of CagA-positive strains are associated with ATDs. These findings suggest that H. pylori infection potentially plays a part in the development of ATDs.

Comparative proteomics of Helicobacter species: the discrimination of gastric and enterohepatic Helicobacter species

Helicobacter pylori is a major human pathogen that infects the gastric mucosa and is responsible for a range of infections including gastritis and gastric carcinoma. Although other bacteria within the Helicobacter genus can also infect the gastric mucosa, there are Helicobacter species that infect alternative sites within the gastrointestinal (GI) tract. Two-dimensional gel electrophoresis was used to compare the cellular proteomes of seven non-pylori Helicobacters (H. mustelae, H. felis, H. cinaedi, H. hepaticus, H. fennelliae, H. bilis and H. cholecystus) against the more extensively characterised H. pylori. The different Helicobacter species showed distinctive 2D protein profiles, it was possible to combine them into a single dataset using Progenesis SameSpots software. Principal Component Analysis was used to search for correlations between the bacterial proteomes and their sites of infection. This approach clearly discriminated between gastric (i.e. those which infect in the gastric mucosa) and enterohepatic Helicobacter species (i.e. those bacteria that infect the small intestine and hepatobillary regions of the GI tract). Selected protein spots showing significant differences in abundance between these two groups of bacteria were identified by LC-MS. The data provide an initial insight into defining those features of the bacterial proteome that influence the sites of bacterial infection.

BIOLOGICAL SIGNIFICANCE

This study demonstrated that representative members of the Helicobacter genus were readily discriminated from each other on the basis of their in vitro whole cell proteomes determined using 2D gel electrophoresis. Despite the intra-species heterogeneity observed it was possible, to demonstrate that the enterohepatic (represented by H. bilis, H. hepaticus, H. fennelliae, H. cinaedi and H. cholecystus) and gastric (represented by H. pylori, H. mustelae, and H. felis) Helicobacters formed discrete groups based on their 2D protein profiles. A provisional proteomic signature was identified that correlated with the typical sites of colonisation of these members of the Helicobacter genus. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.

Pseudomonas fluorescens-like bacteria from the stomach: A microbiological and molecular study

AIM: To characterize oxidase- and urease-producing bacterial isolates, grown aerobically, that originated from antral biopsies of patients suffering from acid peptic diseases.

METHODS: A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production, acid tolerance and aerobic growth. The selected isolates were further characterized by molecular techniques viz. amplifications for 16S rRNA using universal eubacterial and HSP60 gene specific primers. The amplicons were subjected to restriction analysis and partial sequencing. A phylogenetic tree was generated using unweighted pair group method with arithmetic mean (UPGMA) from evolutionary distance computed with bootstrap test of phylogeny. Assessment of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10^-7 mol/L to 10^-1 mol/L.

RESULTS: Of the 258 antral biopsy specimens collected from patients, 179 (69.4%) were positive for urease production by rapid urease test and 31% (80/258) yielded typical Helicobacter pylori (H. pylori) after 5-7 d of incubation under a microaerophilic environment. A total of 240 (93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight incubation. The partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species. A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens (P. fluorescens). On the basis of HSP60 sequences applied to the UPGMA phylogenetic tree, it was observed that isolated strains in an aerobic environment were likely to be P. fluorescens, and HSP60 sequences had more discriminatory potential rather than 16S rRNA sequences. Interestingly, this bacterium was acid tolerant for hours at low pH. Further, a total of 250 (96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive for the 613 bp amplicons by targeting P. fluorescens-specific conserved putative outer membrane protein gene sequences.

CONCLUSION: This study indicates that bacterial isolates from antral biopsies grown aerobically were P. fluorescens, and thus acid-tolerant bacteria other than H. pylori can also colonize the stomach and may be implicated in pathogenesis/protection.

Association between common genetic variant of HRH2 and gastric cancer risk

Histamine plays important physiological roles in the upper gastrointestinal tract and acts via the H2 receptor. The -1018 G>A (rs2067474) in an enhancer element of the promoter and non-synonymous rs79385261 (Asn46Thr) were identified in HRH2. We attempted to clarify the associations of these polymorphisms with gastric carcinogenesis. The study was performed in 321 patients with gastric cancer and 599 subjects with no evidence of gastric malignancies on upper gastroduodenal endoscopy. The genotypes were determined using a one-tube multiplex PCR-SSCP method. The degree of gastritis was assessed in 496 subjects and serum pepsinogen (PG) I/II levels were measured in 124 subjects without gastric cancer. The minor allele of Asn46Thr could not be detected. The frequencies of the -1018 A allele in the non-GC and GC groups were 13.5% and 8.26%, respectively (p=0.00077). Overall, -1018 GG homozygotes had an increased risk for developing gastric cancer (OR 1.68; 95% CI 1.17-2.42; p=0.0052), especially intestinal type cancer (OR 1.94; 95% CI 1.23-3.08; p=0.0047). In subjects aged >60 years, the adjusted risk for gastric cancer among individuals who were -1018 GG homozygotes was 1.87 (range 1.19-2.93; p=0.0065) compared with A carriers. In the gastric cancer cases located in the antrum and at comparative advanced stage, -1018 GG homozygosity was a significantly increased risk factor. In subjects >60 years, the metaplasia score was significantly higher in -1018 GG homozygotes than A carriers. Both atrophy and metaplasia scores were significantly increased with age only in -1018 GG homozygotes. The PG I/II ratio was significantly decreased in H. pylori positive GG homozygotes than negative GG homozygotes and positive A carriers. Our results suggest that -1018 GG homozygosity of HRH2 may be associated with the severity of gastric mucosal atrophy. This genotype has an increased risk for the subsequent development of gastric cancer, especially intestinal type, at advanced age.

In vitro antibacterial and morphological effects of the urushiol component of the sap of the Korean lacquer tree (Rhus vernicifera Stokes) on Helicobacter pylori

Eradication regimens for Helicobacter pylori infection have some side effects, compliance problems, relapses, and antibiotic resistance. Therefore, alternative anti-H. pylori or supportive antimicrobial agents with fewer disadvantages are necessary for the treatment of H. pylori. We investigated the pH-(5.0, 6.0, 7.0, 8.0, 9.0, and 10.0) and concentration (0.032, 0.064, 0.128, 0.256, 0.514, and 1.024 mg/mL)-dependent antibacterial activity of crude urushiol extract from the sap of the Korean lacquer tree (Rhus vernicifera Stokes) against 3 strains (NCTC11637, 69, and 219) of H. pylori by the agar dilution method. In addition, the serial (before incubation, 3, 6, and 10 min after incubation) morphological effects of urushiol on H. pylori were examined by electron microscopy. All strains survived only within pH 6.0-9.0. The minimal inhibitory concentrations of the extract against strains ranged from 0.064 mg/mL to 0.256 mg/mL. Urushiol caused mainly separation of the membrane, vacuolization, and lysis of H. pylori. Interestingly, these changes were observed within 10 min following incubation with the 1xminimal inhibitory concentrations of urushiol. The results of this work suggest that urushiol has potential as a rapid therapeutic against H. pylori infection by disrupting the bacterial cell membrane.

Effect of bile salts on the DNA and membrane integrity of enteric bacteria

Enteric bacteria are able to resist the high concentrations of bile encountered throughout the gastrointestinal tract. Here we review the current mechanisms identified in the enteric bacteria Salmonella, Escherichia coli, Bacillus cereus and Listeria monocytogenes to resist the dangerous effects of bile. We describe the role of membrane transport systems, and their connection with DNA repair pathways, in conferring bile resistance to these enterics. We discuss the findings from recent investigations that indicate bile tolerance is dependent upon being able to resist the detergent properties of bile at both the membrane and DNA level.

Barrett's esophagus is characterized by the absence of Helicobacter pylori infection and high levels of serum pepsinogen I concentration in Japan

BACKGROUND AND AIM

It has been reported that patients with Barrett's esophagus (BE) may have gastric acid hypersecretion. Serological markers such as serum pepsinogen or gastrin have been used to estimate the gastric secretory function. The aim of this study was to compare the serum pepsinogen and gastrin concentrations in view of Helicobacter pylori infection status between BE patients and the controls.

METHODS

Thirty-six patients with long-segment BE were enrolled in this study. Three age- and sex-matched controls were assigned to each patient. Serum pepsinogen and gastrin concentrations were measured by radioimmunoassay and H. pylori infection was determined by histology and serum IgG antibodies.

RESULTS

Helicobacter pylori infection was present in 4 of 36 patients (11%) with BE and in 80 of 108 controls (74%), being less prevalent in BE patients than in the controls (P < 0.0001). When examined in the H. pylori-negative subjects, both the serum pepsinogen I and pepsinogen II concentrations in BE patients were significantly higher than those in the controls (mean pepsinogen I:BE 51.0 +/- 14.0 ng/mL vs control 38.9 +/- 13.5 ng/mL, P = 0.0012; mean pepsinogen II:BE 10.8 +/- 4.0 ng/mL vs control 7.9 +/- 2.0 ng/mL, P = 0.0097). There was no significant difference in the serum gastrin levels between BE patients and the controls irrespective of the H. pylori infection status.

CONCLUSIONS

Most of the Japanese BE patients are characterized by the absence of H. pylori infection and high levels of serum pepsinogen. Determination of the serum pepsinogen level in combination with the H. pylori infection status could be a useful serological marker for BE screening.

Helicobacter pylori prevalence in diabetes mellitus patients with dyspeptic symptoms and its relationship to glycemic control and late complications

BACKGROUND

There are contradictory reports on Helicobacter pylori prevalence and its relationship to late complications of diabetes mellitus (DM). The aim of this study was to determine the prevalence of H. pylori infection in type 2 DM patients and to evaluate the relationship between H. pylori infection and the glycemic control, late complications.

MATERIAL AND METHOD

A total of 141 type 2 DM patients and 142 nondiabetic subjects with upper gastrointestinal symptoms were enrolled in the study. All patients underwent upper gastrointestinal endoscopy with biopsy specimens obtained from gastric antrum and corpus. H. pylori status was evaluated in each patient by both the rapid urease test and histopathological examination. Plasma glucose, HbA1c, microalbuminuria in 24 h collected urine, electroneuromyography, and fundoscopic examinations were performed in all subjects.

RESULTS

The prevalence of H. pylori infection was 61.7% and 58.5%, respectively, among type 2 diabetic patients and nondiabetic controls and was not statistically significant (P = 0.577). The duration of diabetes, fasting blood glucose and haemoglobin A1c levels, nephropathy and retinopathy prevalence did not differ significantly between the two groups (diabetics versus nondiabetics). There was no late complication in 60.3% of the type 2 diabetic patients as compared to at least one late complication in the remainders. A statistically significant correlation was found between H. pylori infection and the presence of neuropathy (P = 0.021).

CONCLUSIONS

The prevalence of H. pylori infection did not differ significantly between the diabetic patients and nondiabetic controls. Interestingly, diabetics with H. pylori infection had a higher incidence of neuropathy, although there was no association between the duration and regulation of diabetes, retinopathy, nephropathy and H. pylori status.

Identification of Campylobacter jejuni genes contributing to acid adaptation by transcriptional profiling and genome-wide mutagenesis

In order to cause disease, the food- and waterborne pathogen Campylobacter jejuni must face the extreme acidity of the host stomach as well as cope with pH fluctuations in the intestine. In the present study, C. jejuni NCTC 11168 was grown under mildly acidic conditions mimicking those encountered in the intestine. The resulting transcriptional profiles revealed how this bacterium fine-tunes gene expression in response to acid stress. This adaptation involves the differential expression of respiratory pathways, the induction of genes for phosphate transport, and the repression of energy generation and intermediary metabolism genes. We also generated and screened a transposon-based mutant library to identify genes required for wild-type levels of growth under mildly acidic conditions. This screen highlighted the important role played by cell surface components (flagella, the outer membrane, capsular polysaccharides, and lipooligosaccharides) in the acid stress response of C. jejuni. Our data also revealed that a limited correlation exists between genes required for growth under acidic conditions and genes differentially expressed in response to acid. To gain a comprehensive picture of the acid stress response of C. jejuni, we merged transcriptional profiles obtained from acid-adapted cells and cells subjected to acid shock. Genes encoding the transcriptional regulator PerR and putative oxidoreductase subunits Cj0414 and Cj0415 were among the few up-regulated under both acid stress conditions. As a Cj0415 mutant was acid sensitive, it is likely that these genes are crucial to the acid stress response of C. jejuni and consequently are important for host colonization.

Natural transformation increases the rate of adaptation in the human pathogen Helicobacter pylori

Gene exchange between individuals can lead to profound evolutionary effects at both the genomic and population levels. These effects have sparked widespread interest in examining the specific adaptive benefits of recombination. Although this work has primarily focused on the benefits of sex in eukaryotes, it is assumed that similar benefits of genetic exchange apply across eukaryotes and prokaryotes. Here we report a direct test of this assumption using the naturally transformable human gastric pathogen Helicobacter pylori as a model organism. We show that genetic exchange accelerates adaptation to a novel laboratory environment within bacterial populations and that a general adaptive advantage exists for naturally transformable strains when transfer occurs among conspecific backgrounds. This finding demonstrates that there are generalized benefits to adaptation in both eukaryotes and prokaryotes even though the underlying processes are mechanistically different.

A novel phenol-bound pectic polysaccharide from Decalepis hamiltonii with multi-step ulcer preventive activity

AIM: To investigate H⁺, K⁺-ATPase inhibition, anti-H pylori, antioxidant, and the in vivo antiulcer potential of a pectic polysaccharide from Swallow root (Decalepis hamiltonii; SRPP).

METHODS: SRPP, with known sugar composition [rhamnose: arabinose: xylose: galactose in the ratio of 16:50:2:32 (w/w), with 141 mg/g of uronic acid] was examined for anti-ulcer potency in vivo against swim/ethanol stress-induction in animal models. Ulcer index, antioxidant/antioxidant enzymes, H⁺, K⁺-ATPase and gastric mucin levels were determined to assess the anti-ulcer potency. Anti-H pylori activity was also determined by viable colony count and electron microscopic studies.

RESULTS: SRPP, containing phenolics at 0.12 g GAE/g, prevented stress-induced gastric ulcers in animal models by 80%-85%. Down regulation of gastric mucin 2-3 fold, antioxidant/antioxidant enzymes and upregulation of 3 fold of H⁺, K⁺-ATPase in ulcerous animals were normalized upon treatment with SRPP. Histopathological analysis revealed protection to the disrupted gastric mucosal layer and epithelial glands. SRPP also inhibited H⁺, K⁺-ATPase in vitro, at an IC₅₀ of 77 μg/mL as opposed to that of 19.3 μg/mL of Lansoprazole and H pylori growth at Minimum Inhibitory Concentration (MIC) of 150 μg/mL. In addition, free radical scavenging (IC₅₀-40 μg/mL) and reducing power (3200 U/g) activities were also observed.

CONCLUSION: SRPP, with defined sugar composition and phenolics, exhibited multi-potent free radical scavenging, antioxidant, anti-H pylori, inhibition of H⁺, K⁺-ATPase and gastric mucosal protective activities. In addition, SRPP is non-toxic as opposed to other known anti-ulcer drugs, and therefore may be employed as a potential alternative for ulcer management.

Inhibition of gastric H(+),K(+)-ATPase and Helicobacter pylori growth by phenolic antioxidants of Curcuma amada

Gastric ulcer is the most prevalent gastrointestinal disorder, resulting from oxidative stress, Helicobacter pylori infection, up-regulation of proton potassium ATPase (PPA) activity, down-regulation of gastric mucosal defense, etc. In this paper it is reported that phenolic fractions of Curcuma amada, commonly known as mango ginger, acted as potent inhibitors of PPA and H. pylori growth. Mango ginger free phenolics (MGFP) and mango ginger bound phenolics (MGBP) inhibited PPA at IC50 values of 2.2 +/- 0.21 and 0.7 +/- 0.08 microg/mL, respectively, exhibiting 9-27-fold better potency over lansoprazole (IC(50) of 19.3 +/- 2.2 microg/mL). MGFP is constituted by caffeic (26%), gentisic (24%), ferulic (20%), gallic (10%), cinnamic (7%), and protocatechuic acids (7%) and MGBP by ferulic (47%), cinnamic (29%), p-coumaric acid (11%), and syringic (5%) acids as major phenolic acids. MGFP and MGBP further exhibited free radical scavenging (IC(50) of 2.2 +/- 0.17 and 4.2 +/- 0.36 microg/mL), reducing power abilities (193-104 units/g), inhibition of lipid peroxidation (IC(50) of 10.3 +/- 0.91 and 15.6 +/- 1.6 microg/mL), and DNA protection (80% at 4 microg), indicating strong antioxidative properties. MGFP and MGBP thus may be potential and inexpensive multistep blockers against ulcers.

Pharmacoeconomic comparison of Helicobacter pylori eradication regimens

BACKGROUND

Helicobacter pylori is the most important etiologic agent for development of peptic ulcer, chronic gastritis and gastric carcinomas. It is now well established that H. pylori eradication treatment is more cost-effective than acid suppressing therapies alone for the treatment of peptic ulcer disease. However, the comparative cost-effectiveness of various H. pylori eradication regimens is still not clear.

OBJECTIVE

This study was designed to make a pharmacoeconomic comparison of different H. pylori eradication regimens in patients with peptic ulcer disease or chronic gastritis, using real-world cost and effectiveness data.

SETTING

Istanbul University Hospital and Marmara University Hospital.

METHOD

A total of 75 patients diagnosed as H. pylori (+) by endoscopy were randomized to receive one of the seven H. pylori treatment protocols. These protocols were as follows: (LAC) = 'lansoprazole 30 mg bid + amoxicillin 1 g bid + clarithromycin 500 mg bid' for 7 days and (OCM) = 'omeprazole 20 mg bid + clarithromycin 250 mg bid + metronidazole 500 mg bid'; (OAM) = 'omeprazole 40 mg qd + amoxicillin 500 mg tid + metronidazole 500 mg tid'; (MARB) = 'metronidazole 250 mg tid + amoxicillin 500 mg qid + ranitidine 300 mg hs + bismuth 300 mg qid'; (OAC) = omeprazole 20 mg bid + amoxicillin 1 g bid + clarithromycin 500 mg bid'; (OCA) = omeprazole 40 mg bid + clarithromycin 500 mg bid + amoxicillin 1 g bid'; (OAB) = 'omeprazole 20 mg bid + amoxicillin 500 mg tid + bismuth 300 mg qid' each for 14 days. Only direct costs were included in the analysis. Effectiveness was measured in terms of "successful eradication". The cost-effectiveness ratios of the regimens were calculated using these effectiveness and cost data. The perspective of the study was assumed as the Government's perspective.

MAIN OUTCOME MEASURE

Cost-effectiveness ratios of eradication regimens.

RESULTS

MARB and OCA regimens were found to be more cost-effective than the other treatment regimens. The eradication rates and cost-effectiveness ratios calculated for these protocols were 90% (158.7 euros) for MARB and 90% (195.8 euros) for OCA regimen.

CONCLUSION

This study confirms the importance of using local pharmacoeconomic data. Analyses such as this give decision-makers the tools to choose a better treatment option which is both highly effective yet and has a low cost.

Requirement of histidine kinases HP0165 and HP1364 for acid resistance in Helicobacter pylori

In this study, we investigated a potential requirement of two-component signal transduction systems for acid resistance in Helicobacter pylori. In comparison to a wild-type strain, isogenic strains with null mutations in either HP0165 or HP1364 histidine kinases were impaired in their ability to grow at pH 5.0. The growth of complemented mutant strains was similar to that of the wild-type strain. H. pylori DNA array analyses and transcriptional reporter assays indicated that acid-responsive gene transcription was altered in the HP0165 and HP1364 null mutant strains compared to the parental wild-type strain. These results indicate that intact HP0165 and HP1364 histidine kinases are required for acid resistance in H. pylori.

Design, synthesis, and anti-Helicobacter pylori activity of erythromycin A (E)-9-oxime ether derivatives

The synthesis and anti-Helicobacter pylori (H. pylori) activity evaluation of a new series of erythromycin A (E)-9-oxime ether derivatives are described. These compounds exhibited comparable in vitro anti-H. pylori activity and improved acid stability compared to the reference compound clarithromycin.

Multiple displacement amplification of isolated DNA from human gallstones: molecular identification of Helicobacter DNA by means of 16S rDNA-based pyrosequencing analysis

BACKGROUND

Molecular typing of Helicobacter spp. in clinical biopsy specimens has become increasingly important. By means of nested polymerase chain reaction (PCR) amplification and Southern blot analysis of the PCR amplicons, we have shown that Helicobacter spp. DNA is present in human gallstones. In this study we have investigated the possibility of using multiple displacement amplification (MDA) of isolated gallstone DNA and pyrosequencing analysis for the molecular identification of Helicobacter spp.

MATERIALS AND METHODS

DNA isolated from the nucleus of 33 human gallstones and one control strain were used in a MDA assay. Subsequently, pyrosequencing analysis was performed either directly on MDA-DNA using primers flanking the Helicobacter spp. 16S rDNA variable V3 region or on PCR amplicons derived from broad-range primers flanking the 16S rDNA variable V3, V4, and V9 regions.

RESULTS

Pyrosequencing analysis of 16S rDNA derived from MDA-DNA revealed that Helicobacter spp.-like DNA was present in 25 of 33 (approximately 76%) gallstones. Using an H. pylori-specific Southern blot analysis, Helicobacter spp.-like DNA was present in 20 of 33 [approximately 61%] of the gallstones. Using MDA-DNA directly in pyrosequencing analysis, Helicobacter spp.-like DNA was present in 13 of 33 [approximately 39%] gallstones.

CONCLUSIONS

We conclude that multiple displacement amplification combined with pyrosequencing enables a rapid and accurate molecular typing of Helicobacter spp. from small and precious biopsy specimens.

Substrate specificity of Helicobacter pylori histone-like HU protein is determined by insufficient stabilization of DNA flexure points

The histone-like HU protein is ubiquitous in the eubacteria. A role for Escherichia coli HU in compaction of the bacterial genome has been reported, along with regulatory roles in DNA replication, transposition, repair and transcription. We show here that HU from the human pathogen Helicobacter pylori, which has been implicated in the development of ulcers and gastric cancer, exhibits enhanced thermal stability and distinct DNA substrate specificity. Thermal denaturation of HpyHU (H. pylori HU) measured by CD spectroscopy yields a melting temperature (T(m)) of 56.4+/-0.1 degrees C. HpyHU binds linear duplex DNA with a site size of approximately 19 bp and with low affinity, but in striking contrast to E. coli HU, HpyHU has only modest preference for DNA with mismatches, nicks or gaps. Instead, HpyHU binds stably to four-way DNA junctions with half-maximal saturation of 5 nM. Substitution of two residues adjacent to the DNA-intercalating prolines attenuates both the preference for flexible DNA and the ability to bend and supercoil DNA. These observations suggest that proline intercalation generates hinges that must be stabilized by adjacent residues; insufficient stabilization leads to reduced bending and a failure to bind preferably to DNA with flexure points, such as gaps and mismatches.

Role of noninvasive tests (C-urea breath test and stool antigen test) as additional tools in diagnosis of Helicobacter pylori infection in patients with atrophic body gastritis

BACKGROUND

Detection of Helicobacter pylori infection in atrophic body gastritis (ABG) is difficult, as during progression of body atrophy, H. pylori disappears.

AIM

To increase the diagnostic yield of detection of active H. pylori infection in atrophic body gastritis patients by using noninvasive tests such as (13)C-Urea Breath Test ((13)C-UBT) and H. pylori stool antigen test (HpSA) would be useful.

PATIENTS

27 consecutive patients with newly-diagnosed atrophic body gastritis (19F/7M, age 27-73 years).

METHODS

Gastroscopy with biopsies (antrum n = 3, body n = 3) and histology according to updated Sydney system, H. pylori IgG serology, (13)C-UBT, and HpSA.

RESULTS

All tests used in the diagnosis of H. pylori infection were in agreement in 9/27 atrophic body gastritis patients (33.3%), being all positive in four (14.8%) and all negative in five patients (18.5%). Ten of the 27 (37%) patients were Giemsa stain-positive and serology-positive (group I). Seventeen of the 27 (63%) patients were Giemsa stain-negative: 5/17 with positive serology (group II) and 12/17 with negative serology (group III). In group I, 5/10 (50%) were (13)C-UBT positive and 4/10 (40%) HpSA positive. In group II, two patients were (13)C-UBT positive, but all were HpSA negative. Also in group III, all patients were HpSA negative, but one had a positive (13)C-UBT.

CONCLUSIONS

In atrophic body gastritis patients, neither (13)C-UBT nor HpSA per se add useful information regarding active H. pylori infection, but these noninvasive tests may be important in combination with histology and serology to define the H. pylori status in some atrophic body gastritis patients.

Crystal structure of CagZ, a protein from the Helicobacter pylori pathogenicity island that encodes for a type IV secretion system

CagZ, a 23 kDa protein encoded by the cagZ gene (HP0526) of the cag pathogenicity island of Helicobacter pylori, has been cloned, over-expressed, purified and its three-dimensional structure determined. The protein consists of a single compact L-shaped domain, composed of seven alpha-helices including about 70% of the total residues. Three-dimensional homology searches did not reveal structural homologues, and CagZ can be considered representative of a new protein fold. The presence of a disordered C-terminal tail and the nature of the molecular surface suggest that CagZ may participate in the interaction of effector proteins with one or more components of the H.pylori type IV secretion system on the cytoplasmic side of the inner membrane.

A model for the study of Helicobacter pylori interaction with human gastric acid secretion

We present a comprehensive mathematical model describing Helicobacter pylori interaction with the human gastric acid secretion system. We use the model to explore host and bacterial conditions that allow persistent infection to develop and be maintained. Our results show that upon colonization, there is a transient period (day 1-20 post-infection) prior to the establishment of persistence. During this period, changes to host gastric physiology occur including elevations in positive effectors of acid secretion (such as gastrin and histamine). This is promoted by reduced somatostatin levels, an inhibitor of acid release. We suggest that these changes comprise compensatory mechanisms aimed at restoring acid to pre-infection levels. We also show that ammonia produced by bacteria sufficiently buffers acid promoting bacteria survival and growth.

Age at acquisition of Helicobacter pylori infection: comparison of two areas with contrasting risk of gastric cancer

BACKGROUND

Helicobacter pylori infection is usually acquired during childhood and is a known risk factor for the development of gastric malignancies in adulthood. It has been reported that early age at first infection may determine a neoplastic outcome in adults. The purpose of this study was to determine the prevalence of Helicobacter pylori infection in children residing in areas with high (Pasto) and low risk (Tumaco) of gastric cancer in Colombia to evaluate whether differences in the age of acquisition of H. pylori infection were present in the two populations.

MATERIALS AND METHODS

The study sample was based on a census taken in 1999. Using the (13)C-urea breath test, we compared the prevalence of H. pylori infection among children aged 1-6 years.

RESULTS

Among 345 children in Pasto, 206 (59.7%) were H. pylori-positive, compared with 188 (58.6%) among 321 children in Tumaco. The two populations share a common pattern of very early age at infection and marked increase in prevalence during the first 4 years of life. No differences in any one year were observed when comparing the two groups.

CONCLUSIONS

The prevalence of infection was similarly high and increased with age in both populations. In these populations the age of acquisition of H. pylori after 1 year of age does not appear to be a primary factor responsible for the differences in the rates of gastric cancer incidence in adults. Previous findings in adults showed lower prevalence of the most virulent genotypes in Tumaco compared to Pasto, and bacterial virulence may play a key role in determining cancer outcome.

Effects of Helicobacter pylori infection on the link between regenerating gene expression and serum gastrin levels in Mongolian gerbils

Although regenerating gene (Reg) protein is reported to have a trophic effect on gastric epithelial cells, its involvement in human gastric diseases is not clear. We have recently shown that both gastrin and gastric mucosal inflammation enhance Reg gene expression in the fundic mucosa in rats. This study was designed to clarify whether Reg protein is involved in Helicobacter pylori-induced gastritis and whether Reg gene expression is linked to serum gastrin levels in this condition. Mongolian gerbils were inoculated with an H. pylori strain isolated from a gastric cancer patient. Four weeks later, some of the gerbils with H. pylori infection were eradicated by lansoprazole, amoxicillin, and clarithromycin. The time courses of changes in Reg gene expression, serum gastrin levels, gastric acidity, and histopathologic factors were examined. Four weeks after H. pylori infection, gastritis started spreading to the fundic mucosa, and gastric acidity started reducing. Serum gastrin levels and Reg mRNA expression in the fundus were significantly increased 6 weeks after infection. Reg mRNA expression in the fundus correlated significantly with both serum gastrin levels and the severity of fundic mucosal inflammation. After H. pylori eradication, serum gastrin levels and fundic mucosal inflammation were normalized, and the increase in Reg mRNA expression was abolished. The Reg gene is associated with hypergastrinemia and fundic mucosal inflammation and may be involved in H. pylori-induced gastritis.

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Promoter analysis of Helicobacter pylori genes with enhanced expression at low pH

To identify Helicobacter pylori genes with expression that is enhanced under low pH conditions, we used subtractive hybridization methodology. We identified 28 acid-induced genes, of which 18 have known or putative functions. Six pairs of genes were co-transcribed. Primer extension analysis identified single or multiple transcriptional start points (tsp) for 14 of the 22 loci. Sequence analysis of the -10 regions upstream of the tsps revealed consensus motifs for multiple RNA polymerase sigma factors present in H. pylori (sigma80, sigma54 and sigma28). No sequences resembling the -35 Escherichia coli consensus sequence (TTGACA) were present upstream of any of the genes. Both increased gene transcription and decreased mRNA decay contribute to the observed increase in H. pylori transcript abundance at acid pH. These studies document the complex response of H. pylori to environmental pH changes, and provide insight into mechanisms used for intragastric survival.

Medium pH-dependent redistribution of the urease of Helicobacter pylori

Helicobacter pylori is an aetiological agent of gastric disease. Although the role of urease in gastric colonization of H. pylori has been shown, it remains unclear as to where urease is located in this bacterial cell. The purpose of this study was to define the urease-associated apparatus in the H. pylori cytoplasm. H. pylori was incubated at both a neutral and an acidic pH in the presence or absence of urea and examined by double indirect immunoelectron microscopy. The density of gold particles for UreA was greatest in the inner portion of the wild-type H. pylori cytoplasm at neutral pH but was greatest in the outer portion at acidic pH. This difference was independent of the presence of urea and was not observed in the ureI-deletion mutant. Also, the eccentric shift of urease in acidic pH was not observed in UreI. After a 2 day incubation period at acidic pH, it was observed that the urease gold particles in H. pylori assembled and were associated with UreI gold particles. Urease immunoreactivity shifted from the inner to the outer portion of H. pylori as a result of an extracellular decrease in pH. This shift was urea-independent and UreI-dependent, suggesting an additional role of UreI in urease-dependent acid resistance. This is the first report of the intracellular transport of molecules in bacteria in response to changes in the extracellular environment.

Enterocromaffin-like cell tumor induced by Helicobacter pylori infection in Mongolian gerbils

BACKGROUND

Gastric carcinoids are strongly associated with chronic atrophic gastritis A, and it is suggested that hypergastrinemia plays a critical role in development of gastric carcinoids. Since Helicobacter pylori infection causes hypergastrinemia, it is held that H. pylori infection produces gastric carcinoids. We followed the histological changes of H. pylori-infected stomachs of Mongolian gerbils for a long time.

MATERIALS AND METHODS

Five-week-old-male Mongolian gerbils were infected with H. pylori ATCC 43504 with cagA gene, expressing vacuolating cytotoxin. Determination of the serum gastrin and histopathological examination of the stomach at 6, 12, 18, and 24 months after H. pylori inoculation was studied and compared with uninfected animals.

RESULTS

In infected animals, the gastric carcinomas appeared 18 and 24 months after infection. Endocrine cell dysplasias and carcinoids with marked atrophic gastritis of the oxyntic mucosa were observed in the infected animals 24 months after H. pylori inoculation. The serum gastrin level in the infected group increased from an average of 86.2 pg/ml at the beginning of the study to an average of 498 pg/ml and 989 pg/ml at 18 and 24 months after infection, respectively. These changes in the serum gastrin levels were significant compared with uninfected controls that showed no changes.

CONCLUSIONS

H. pylori infection caused not only gastric carcinomas but also enterochromaffin-like cell tumors in Mongolian gerbils, due to hypergastrinemia. This model is thought to be useful to study the relationship between hypergastrinemia and gastric carcinoids.

Parallel synthesis of potent, pyrazole-based inhibitors of Helicobacter pylori dihydroorotate dehydrogenase

The identification of several potent pyrazole-based inhibitors of bacterial dihydroorotate dehydrogenase (DHODase) via a directed parallel synthetic approach is described below. The initial pyrazole-containing lead compounds were optimized for potency against Helicobacter pylori DHODase. Using three successive focused libraries, inhibitors were rapidly identified with the following characteristics: K(i) < 10 nM against H. pylori DHODase, sub-microg/mL H. pylori minimum inhibitory concentration activity, low molecular weight, and >10 000-fold selectivity over human DHODase.