Association of CagA-positive and CagA-negative Helicobacter pylori strains with patients' symptoms and gastritis in primary care patients with functional upper abdominal complaints

Unwelcome guests - the role of gland-associated Helicobacter pylori infection in gastric carcinogenesis

Helicobacter pylori (H. pylori) are Gram-negative bacteria that cause chronic gastritis and are considered the main risk factor for the development of gastric cancer. H. pylori have evolved to survive the harsh luminal environment of the stomach and are known to cause damage and signaling aberrations in gastric epithelial cells, which can result in premalignant and malignant pathology. As well as colonizing the gastric mucus and surface epithelial cells, a subpopulation of H. pylori can invade deep into the gastric glands and directly interact with progenitor and stem cells. Gland colonization therefore bears the potential to cause direct injury to long-lived cells. Moreover, this bacterial subpopulation triggers a series of host responses that cause an enhanced proliferation of stem cells. Here, we review recent insights into how gastric gland colonization by H. pylori is established, the resulting pro-carcinogenic epithelial signaling alterations, as well as new insights into stem cell responses to infection. Together these point towards a critical role of gland-associated H. pylori in the development of gastric cancer.

Long-chain fatty acids alter transcription of Helicobacter pylori virulence and regulatory genes

Infection with Helicobacter pylori is one of the most important risk factors for developing gastric cancer (GC). The type IV secretion system (T4SS) encoded in the cag pathogenicity island is the main virulence factor of H. pylori associated with GC. Additionally, other virulence factors have been shown to play a role in the H. pylori virulence, such as vacuolizing cytotoxin (VacA), urease, flagella, and adhesins. Long-chain fatty acids (LCFAs) are signaling molecules that affect the transcription of virulence genes in several pathogenic bacteria such as Salmonella enterica, Vibrio cholerae, Pseudomonas aeruginosa and Mycobacterium tuberculosis. However, the effect of LCFAs on the transcription of H. pylori virulence and regulatory genes remains unknown. Here we analyzed whether the transcription of virulence genes that encode T4SS and cellular envelope components, flagellins, adhesins, toxins, urease, as well as the transcription of different regulatory genes of the H. pylori strain 26695, are altered by the presence of five distinct LCFAs: palmitic, stearic, oleic, linoleic, and linolenic acids. Palmitic and oleic acids up-regulated the transcription of most of the virulence genes tested, including cagL, cagM, flaB, sabA, mraY and vacA, as well as that of the genes encoding the transcriptional regulators NikR, Fur, CheY, ArsR, FlgR, HspR, HsrA, Hup, and CrdR. In contrast, the other LCFAs differentially affected the transcription of the virulence and regulatory genes assessed. Our data show that LCFAs can act as signaling molecules that control the transcription of the H. pylori virulome.

Rapid Characterization of Virulence Determinants in Helicobacter pylori Isolated from Non-Atrophic Gastritis Patients by Next-Generation Sequencing

Helicobacter pylori is a major human pathogen that causes a wide range of gastrointestinal pathology. Progression of H. pylori induced gastritis to more severe disease has been found to highly correlate with the array of virulence factors expressed by the pathogen. The objective of this study was twofold: first, to characterize the genetic diversity of H. pylori strains isolated from 41 non-atrophic gastritis patients in Switzerland, an issue that has not been investigated to date. And second, to assess the prevalence and sequence variation of H. pylori virulence factors (cagA, vacA, iceA and dupA) and genes encoding outer membrane proteins (OMPs; babA, babB, sabA, sabB, hopZ, hopQ and oipA) by whole genome sequencing (WGS) using an Illumina MiSeq platform. WGS identified high genetic diversity in the analyzed H. pylori strains. Most H. pylori isolates were assigned to hpEurope (95.0%, 39/41), and the remaining ones (5.0%, 2/41) to hpEastAsia, subpopulation hspEAsia. Analysis of virulence factors revealed that 43.9% of the strains were cagA-positive, and the vacA s1 allele was detected in 56.0% of the isolates. The presence of cagA was found to be significantly associated (P < 0.001) with the presence of vacA s1, babA2 and hopQ allele 1 as well as expression of oipA. Moreover, we found an association between the grade of gastritis and H. pylori abundance in the gastric mucosa, respectively and the presence of cagA, vacA s1 and hopQ allele 1. Among our 41 gastritis patients, we identified seven patients infected with H. pylori strains that carried a specific combination of virulence factors (i.e., cagA, vacA s1 allele and babA2 allele), recently implicated in the development of more severe gastrointestinal pathology, like peptic ulcer disease and even gastric cancer. To this end, WGS can be employed for rapid and detailed characterization of virulence determinants in H. pylori, providing valuable insights into the pathogenic capacity of the bacterium. This could ultimately lead to a higher level of personalized treatment and management of patients suffering from H. pylori associated infections.

Association of heterogenicity of Helicobacter pylori cag pathogenicity island with peptic ulcer diseases and gastric cancer

OBJECTIVE

To investigate the frequency and integrity of certain cag pathogenicity island genes (cagPAI) in Helicobacter pylori strains and their association with peptic ulcer disease (PUD) and gastric cancer.

MATERIAL AND METHODS

We enrolled 240 adult patients [120 with functional dyspepsia (FD), 50 with PUD and 70 with gastric cancer] undergoing upper gastrointestinal endoscopy. H. pylori infection was diagnosed when either culture or any two of the three tests (rapid urease test, histopathology and specific ureA PCR) were positive. DNA extracted from H. pylori isolates and positive gastric tissues were tested by PCR for the presence of different genes of cagPAI using specific primers.

RESULTS

A total of 122 (51%) patients were H. pylori positive. Frequencies of cagPAI genes cagA, cagE, cagT and cagM in H. pylori strains from different groups of patients were as follows: functional dyspepsia 73, 83, 76 and 60%, PUD 70, 94, 91, 70% and gastric cancer 75, 95, 90 and 70%, respectively. Risk associated for the presence of PUD and gastric cancer with cagPAI genes cagE, cagT and cagM was 5.0-, 4.6- and 4.1- and 3.0-, 2.8- and 2.5-folds, respectively. Prevalence of intact cagPAI was significantly higher in PUD and gastric cancer compared to functional dyspepsia (PUD vs. functional dyspepsia, 71% vs. 38%, P = 0.01; gastric cancer vs. functional dyspepsia, 75% vs. 38%, P < 0.01). Intact cagPAI was associated with increased risk for the presence of PUD (odds ratio 5.2, 95% CI 2.4-11.3) and for the presence of gastric cancer (odds ratio 4.5, 95% CI 2.3-7.1).

CONCLUSIONS

cagPAI integrity and its different genes are linked to different forms of gastric disease and so may have a role in pathogenesis, diagnosis and management.

Association of Helicobacter pylori infection with chronic atrophic gastritis: Meta-analyses according to type of disease definition

Helicobacter pylori is a major risk factor for chronic atrophic gastritis (CAG). A large variety of definitions of CAG have been used in epidemiologic studies in the past. The aim of this work was to systematically review and summarize estimates of the association between H. pylori infection and CAG according to the various definitions of CAG. Articles on the association between H. pylori infection and CAG published until July 2007 were identified. Separate meta-analyses were carried out for studies defining CAG based on gastroscopy with biopsy, serum pepsinogen I (PG I) only, the pepsinogen I/pepsinogen II ratio (PG I/PG II ratio) only, or a combination of PG I and the PG I/PG II ratio. Numbers of identified studies and summary odds ratios (OR) (95% confidence intervals) were as follows: gastroscopy with biopsy: n = 34, OR = 6.4 (4.0-10.1); PG I only: n = 13, OR = 0.9 (0.7-1.2); PG I/PG II ratio: n = 8, OR = 7.2 (3.1-16.8); combination of PG I and the PG I/PG II ratio: n = 20, OR = 5.7 (4.4-7.5). Studies with CAG definitions based on gastroscopy with biopsy or the PG I/PG II ratio (alone or in combination with PG I) yield similarly strong associations of H. pylori with CAG. The association is missed entirely in studies where CAG is defined by PG I only.

Upper abdominal symptoms in patients with Type 1 diabetes: unrelated to impairment in gastric emptying caused by autonomic neuropathy

AIMS

Diabetic gastroparesis is a common condition occurring in some 30-50% of patients with long-term diabetes. Some studies have found a relationship between autonomic neuropathy and diabetic gastroparesis. In addition to autonomic neuropathy, acute changes in plasma glucose concentration can also affect gastric emptying. The objective was to examine the relationship between autonomic nerve function, glucose concentration, gastric emptying, and upper abdominal symptoms in Type 1 diabetic patients.

METHODS

Gastric emptying of solids and liquids was measured with scintigraphy in 27 patients with longstanding Type 1 diabetes with upper abdominal symptoms. Autonomic nerve function was examined by standardized cardiovascular tests, and plasma glucose concentrations were measured during scintigraphy. Severity of abdominal symptoms and quality of life were explored by validated questionnaires.

RESULTS

Seven patients (26%) had delayed gastric emptying of solids and three (11%) of liquids. Mean gastric half-emptying time of solids was 128 +/- 116 min and of liquids 42 +/- 30 min. Of the 26 patients undergoing tests, 16 (62%) had autonomic nerve dysfunction. Autonomic neuropathy score (1.6 +/- 1.7) correlated positively with the gastric emptying rate of solids (P = 0.006), a rate unrelated to symptom scores or plasma glucose concentrations during scintigraphy. Quality of life in patients with abdominal symptoms was lower than in the normal Finnish population.

CONCLUSIONS

Impaired gastric emptying of solids in patients with Type 1 diabetes is related to autonomic neuropathy, but not to actual glycaemic control. The upper abdominal symptoms observed in these patients cannot be explained, however, by impaired gastric emptying.

Nizatidine and gastric emptying in functional dyspepsia

In clinical practice, H2-receptor antagonists, including nizatidine, in addition to their use in the treatment of peptic ulcer and gastroesophageal reflux, are also useful in alleviating dyspeptic symptoms. Patients with functional dyspepsia show a tendency to delayed gastric emptying. Results of preliminary studies have demonstrated that nizatidine has a prokinetic effect due to its cholinergic properties. The aim of this study was to evaluate the effect of nizatidine on gastric emptying in patients with functional dyspepsia. Sixteen patients with dyspeptic symptoms referred for gastroscopy by primary care physicians were enrolled in this randomized, placebo-controlled, double-blind cross-over study. They received nizatidine 150 mg twice daily or placebo for 2 months. After a 1-month washout period, the 2-month treatment was repeated, with these patients acting as their own controls. Gastric emptying was measured by scintigraphy, and dyspeptic symptoms and quality of life were evaluated at the end of both treatment periods. Gastric emptying of solids during nizatidine therapy was prolonged (T1/2 110.1 +/- 76.7 vs. 65.6 +/- 23.2 min, P = 0.03), but nizatidine had no effect on gastric emptying of liquids. Nizatidine improved the symptom scores and seven of eight aspects of quality of life - but not significantly. In conclusion, nizatidine decreases the gastric emptying rate of solids without having a significant effect on symptoms or quality of life in functional dyspepsia.

Dyspeptic symptoms associated with Helicobacter pylori infection are influenced by strain and host specific factors

BACKGROUND

Dyspepsia can be associated with H. pylori infection.

AIM

To assess dyspeptic symptoms and potentially influencing factors before and up to 6 months following successful H. pylori eradication therapy.

METHODS

Prospective cohort study involving H. pylori positive subjects from ambulatory or hospitalized care. Main outcome measures were symptoms during baseline and follow-up, the proportion of symptom-free patients, and symptom scores.

RESULTS

After successful eradication, the summary score of all dyspeptic symptoms decreased and during follow-up, the proportion of symptom-free patients was higher in the group with peptic ulcers (69.4% vs. 40.9%, P < 0.0001) than with functional dyspepsia (FD). Regardless of diagnosis, virulent strains of H. pylori were associated with a higher prevalence of epigastric pain before treatment: absolute risk-difference (ARD) with Oip-A: 18.2%, Odds Ratio (OR) 2.35 [1.3-4.2, 95%-CI], P = 0.01; with Cag-A: 24.6%, OR 2.81 [1.6-5], P = 0.01. Low-dose aspirin in part was a major risk factor in FD for previous weight loss bdfore study entry. Post-treatment, non-ulcer patients were more likely to suffer from distention/bloating. Likewise, alcohol induced persistence of nausea and vomiting in this population.

CONCLUSIONS

Dyspeptic symptoms in H. pylori infected patients are more common with virulent strains. Symptoms are more likely to persist despite successful eradication if patients initially harboured virulent strains or concomitant aspirin or alcohol intake are present. In one-third of peptic ulcer patients, symptoms will not be cured 3 months after therapy.

Clinical presentation in relation to diversity within the Helicobacter pylori cag pathogenicity island

OBJECTIVE

This study investigated the genetic diversity of the cag pathogenicity island (PAI) in Helicobacter pylori (H. pylori) in relation to clinical outcome and interleukin (IL)-8 production.

METHODS

Seven genes in the cag PAI (cagA, cagE, cagG, cagM, cagT, open reading frame 13 and 10) were examined by polymerase chain reaction and Southern blot hybridization using H. pylori from 120 patients with different presentations (duodenal ulcer, gastric cancer, gastritis alone). IL-8 production from AGS cells (gastric cancer cell line) cocultured with H. pylori was measured by ELISA.

RESULTS

An intact cag PAI was present in 104 (87%) isolates, and five (4%) had deletions within the cag PAI; 11 (9%) lacked the entire cag PAI. Clinical isolates containing the complete cag PAI induced a greater secretion of IL-8 as compared with those without the cag PAI (3048 +/- 263 vs 480 +/- 28 pg/ml, p < 0.001). Deletion of only cagG reduced IL-8 secretion by two thirds. Deletions of more than one locus reduced IL-8 secretion to background. A similar proportion of H. pylori from patients with gastritis, duodenal ulcer, or gastric cancer had intact cag PAI (88%, 88%, and 85%, respectively). Although the presence of cagG was a better predictor of the presence of an intact cag PAI than cagA or cagE, the presence or absence of any of these genes had no association with clinical presentation.

CONCLUSION

Although the cag PAI plays an important role in IL-8 production, clinical presentation cannot be predicted by the presence of an intact cag PAI or any of these seven cag PAI genes.

Helicobacter pylori eradication and standardized 3-month omeprazole therapy in functional dyspepsia

OBJECTIVES

The role of Helicobacter pylori in functional dyspepsia remains unclear. This study evaluated the long term consequences for symptoms and quality of life in patients with H. pylori-positive functional dyspepsia after H. pylori eradication therapy with a standardized 3-month omeprazole treatment.

METHODS

A total of 151 H. pylori-positive patients with functional dyspepsia were randomized to receive either eradication therapy or placebo-antibiotics. The initial medication was administered in a double-blinded fashion. In addition, to standardize acid suppression, every patient received omeprazole therapy for the first 3-month period. Dyspeptic symptoms were evaluated by a questionnaire every 3 months, and quality of life was measured by a validated RAND 36-item health survey 1.0 questionnaire at the beginning of the study and after 12 months of follow-up. As the main outcome measure, the scores of patients who had received H. pylori eradication therapy and omeprazole were compared with those who received placebo and omeprazole during the 12 months of follow-up.

RESULTS

A total of 136 patients completed the 1-yr follow-up. In all, 77 patients received eradication therapy and 74 patients remained as controls. After 12 months, the mean reduction in the dyspepsia score was 28.8% in patients with H. pylori eradication therapy and 21.7% in the control group. The reduction of dyspepsia was significant (p < 0.0001) in both groups compared to baseline value, but no statistically significant differences in changes of dyspeptic symptoms or in quality of life were demonstrated between the H. pylori eradication therapy group and controls after 1 yr. In both patient groups, regurgitation (p < 0.001) and heartburn (p < 0.01) revealed relapse after cessation of 3-month omeprazole treatment.

CONCLUSIONS

No clear differences in symptoms or in quality of life were found between patients treated with H. pylori eradication therapy and omeprazole compared with patients receiving placebo and omeprazole after 1 yr. Regardless of H. pylori status, omeprazole treatment reduced heartburn and regurgitation. The placebo effect on the symptoms of functional dyspepsia and on quality of life was marked.

Dyspepsia is associated with CagA-positive Helicobacter pylori

OBJECTIVE

The role of Helicobacter pylori in nonulcer dyspepsia is controversial. Speculation has arisen that only strains of H. pylori carrying the CagA virulence factor are important in the development of dyspepsia. The objective of this study was to determine whether nonulcer dyspepsia correlated with CagA-positive H. pylori infection.

METHODS

A total of 435 healthy blood donors and 102 general medicine clinic respondents completed the Bowel Disease Questionnaire and the PRIME-MD survey, a validated screen for common psychiatric disorders. Subjects were classified as cases of nonulcer dyspepsia if they reported pain in the upper abdomen more than six times in the previous year and denied a past or current history of peptic ulcer disease. Study participants were tested for IgG antibodies to H. pylori and the CagA protein.

RESULTS

Clinic respondents were more likely than healthy blood donors to meet the case definition for nonulcer dyspepsia (34% vs 13%, p < 0.001), to be seropositive for H. pylori (54% vs 18%, p < 0.001), and to be CagA seropositive (41% vs 10%, p = 0.01). Logistic regression identified CagA seropositivity (p = 0.03), race (p = 0.001), and positive screens for depression (p = 0.007) or somatization (p < 0.001) as variables independently associated with nonulcer dyspepsia.

CONCLUSION

Infection with a CagA-positive strain of H. pylori is associated with a clinical diagnosis of nonulcer dyspepsia. However, nonulcer dyspepsia was also strongly and independently associated with positive screens for depression or somatization disorder as well as with ethnicity. These potential sources of variance should be considered in the design of future studies evaluating nonulcer dyspepsia.

Helicobacter pylori and functional dyspepsia: a real causal link?

This chapter reviews the evidence for a link between functional dyspepsia and Helicobacter pylori infection from three angles. In the section on pathophysiology, we evaluate how H. pylori could theoretically produce dyspeptic symptoms: many mechanisms can be proposed. In the discussion on epidemiology, we evaluate possible associations between the occurrence of symptoms and infection. Here, many studies claiming a coincidence or chronological sequence of infection and symptoms are criticized because of their poor design. In the section on the improvement of functional dyspepsia by the treatment of H. pylori infection, the conclusion is reached that if such an effect occurs at all--which is unlikely--it is very weak. The controversy on the link between H. pylori infection and functional dyspepsia is presently ongoing. Some authors are still trying to save an elegant concept that once looked so plausible but now has the facts against it.

Antibody response to specific H. pylori antigens in functional dyspepsia, duodenal ulcer disease, and health

OBJECTIVE

The relationship between H. pylori and functional dyspepsia remains controversial. The aim of this study was to identify a potential link between the antibody response to specific H. pylori antigens and functional dyspepsia.

METHODS

A total of 50 consecutive patients with functional dyspepsia, 50 patients with duodenal ulcer (DU), and 150 healthy blood donor control subjects with no history of peptic ulceration were studied. H. pylori status was determined by IgG antibodies using a validated ELISA. In H. pylori-positive subjects, antibodies against specific H. pylori antigens were identified by Western blot.

RESULTS

All DU patients (100%; 95%; CI, 93-100), 30 of 50 patients with functional dyspepsia (60%; 95% CI, 45-74) and 65 of 150 (43.3%; 95% CI, 34.3-51) blood donor controls tested positive for H. pylori. Forty-six of 50 (92%; 95% CI, 81-98) DU patients tested positive for the 91 kDa antigen (vacA) compared with 46 of 65 (69%; 95% CI, 58-81) control subjects and 22 of 30 (73%; 95% CI, 54-88) functional dyspepsia patients (p < 0.01 DU versus controls). Similarly, the 120 kDa antigen (cagA) tended (p < 0.15) to be more prevalent in DU patients (82%; 95% CI, 69-91) compared with controls (69%; 95% CI, 57-80) but not functional dyspepsia (77%; 95% CI, 57-90). No specific H. pylori antigens were associated with dyspepsia subgroups.

CONCLUSION

No specific H. pylori antigens are linked to functional dyspepsia.