Mechanisms involved in Helicobacter pylori induced duodenal ulcer disease: an overview

Utilization of an Automated Latex Agglutination Turbidity Assay for Assessing Gastric Mucosal Alteration during Helicobacter pylori Infection

Background/Aims

: A latex agglutination turbidity (LA) assay to test for serum antibodies has been approved in Japan and Korea for mass screening of Helicobacter pylori infection. In this study, we evaluated the LA assay for diagnosing H. pylori infection and predicting gastric mucosal changes in a Mongolian population.

Methods

: In total, 484 individuals were classified into H. pylori-positive (n=356) and H. pylori-negative (n=128) groups, as determined by histology and H. pylori culture.

Results

: The best cutoff, sensitivity, and specificity values for the LA assay were 18.35 U/mL, 74.2%, and 65.6%, respectively. The LA values in the atrophic gastritis group were statistically higher than those in the other groups (healthy, chronic gastritis, intestinal metaplasia, and gastric cancer, p<0.0001). The cutoff value to distinguish the atrophic gastritis group from the other four groups was 32.0 U/mL, and its area under the curve was 0.673, which was the highest among the E-plate, pepsinogen (PG) I, PG II, and PG I/II ratio tests in our data. The odds ratios for atrophic gastritis determined by the LA assay and PG I test in multiple logistic regression were 2.5 and 1.9, respectively, which were significantly higher than for the other tests.

Conclusions

: The LA assay can determine the risk of atrophic gastritis, which in turn is a considerable risk factor for gastric cancer. We propose using this assay in combination with the PG I/II ratio to avoid missing gastric cancer patients who have a low LA value (less than 32.0 U/mL).

Gastric, Duodenal, and Small Bowel Emergencies

Gastric and small bowel emergencies are often seen in the emergency department and require rapid assessment and intervention as patients can deteriorate quickly. Some of the more frequently seen gastric emergencies include gastric volvulus and peptic ulcer disease, which can present with ischemia, strangulation, perforation, or severe bleeding. Swift diagnosis is crucial to ensuring the proper management whether that is endoscopic or with surgical exploration. Perforated peptic ulcers that are not contained will require surgical intervention, whereas bleeding ulcers can often be controlled with endoscopic interventions.

Unusual Presentation of Helicobacter pylori Infection as PSMA-Avid Gastric Mass

ABSTRACT

68 Ga-PSMA PET/CT is one of the most common imaging uses for prostate cancer imaging. Although initially thought to be specific for prostate cancer, there are many evidences that are coming of its concentration in many other neoplastic and nonneoplastic pathologies. Helicobacter pylori is the most common bacteria causing gastric inflammation and usually presents with gastroduodenal ulcer. Here we present one unusual case of benign gastric mass formation caused by H. pylori infection with PSMA concentration.

Helicobacter pylori And Duodenal Ulcer: Systematic Review Of Controversies In Causation

Background

There are controversies on the causal role of H. pylori in duodenal ulceration. Helicobacter pylori are curved gram-negative microaerophilic bacteria found at the layer of gastric mucous or adherent to the epithelial lining of the stomach. It’s a public health significance bacteria starting from discovery, and the prevalence and severity of the infection varies considerably among populations. H. pylori are a risk for various diseases, while the extent of host response like gastric inflammation and the amount of acid secretion by parietal cells affects the outcome of infection.

Method

Relevant literature were searched from databases such as Google Scholar, PubMed, Hinari, Web of Science, Scopus, and Science Direct.

Result

The review evidence supports a strong causal relation between H. pylori infection and duodenal ulcer, as patients are more likely to be infected by virulent strains which later cause duodenal ulceration. Thus, eradication of H. pylori infection decreases the incidence of duodenal ulcers, and prevents its recurrence by reducing both basal gastrin release and acid secretion without affecting parietal cell sensitivity. On the other hand, some studies show that H. pylori infection is not associated with the development of duodenal ulcers and such a lack of association revealed that duodenal ulceration has different pathogenesis.

Conclusion

Despite controversies observed in the causal role of H. pylori to duodenal ulceration by various studies, Hill criteria of causation proved the presence of a causal relation between H. pylori infection and duodenal ulcers. Other factors are also responsible for the development of duodenal ulcers and such factors are responsible for the differences in the prevalence of the diseases.

Iron bioavailability from a lipid-based complementary food fortificant mixed with millet porridge can be optimized by adding phytase and ascorbic acid but not by using a mixture of ferrous sulfate and sodium iron EDTA

Home fortification with lipid-based nutrient supplements (LNSs) is a promising approach to improve bioavailable iron and energy intake of young children in developing countries. To optimize iron bioavailability from an LNS named complementary food fortificant (CFF), 3 stable isotope studies were conducted in 52 young Beninese children. Test meals consisted of millet porridge mixed with CFF and ascorbic acid (AA). Study 1 compared iron absorption from FeSO4-fortifed meals with meals fortified with a mixture of FeSO4 and NaFeEDTA. Study 2 compared iron absorption from FeSO4-fortifed meals without or with extra AA. Study 3 compared iron absorption from FeSO4-fortified meals with meals containing phytase added prior to consumption, once without or once with extra AA. Iron absorption was measured as erythrocyte incorporation of stable isotopes. In study 1, iron absorption from FeSO4 (8.4%) was higher than that from the mixture of NaFeEDTA and FeSO4 (5.9%; P < 0.05). In study 2, the extra AA increased absorption (11.6%) compared with the standard AA concentration (7.3%; P < 0.001). In study 3, absorption from meals containing phytase without or with extra AA (15.8 and 19.9%, respectively) increased compared with meals without phytase (8.0%; P < 0.001). The addition of extra AA to meals containing phytase increased absorption compared with the test meals containing phytase without extra AA (P < 0.05). These findings suggest that phytase and AA, and especially a combination of the two, but not a mixture of FeSO4 and NaFeEDTA would be useful strategies to increase iron bioavailability from a CFF mixed with cereal porridge.

Biochemical markers of bone metabolism in children with Helicobacter pylori infection

We investigated the biochemical markers of bone metabolism in children with Helicobacter pylori infection. Biochemical markers of bone metabolism and serum levels of vitamin B12, ferritin and estradiol were measured in 41 H. pylori-positive (+) children (23 girls, 18 boys; aged 11.8+/-3 years). Serum levels of intact parathyroid hormone, ss-collagen I carboxy terminal telopeptide, total alkaline phosphatase (ALP), bone-specific ALP, N-terminal cross-links of human procollagen type I, N-mid-osteocalcin, calcium, phosphate, ferritin, and estradiol did not differ significantly between H. pylori(+) and H. pylori negative (-) children. Vitamin B12 levels were significantly decreased in H. pylori(+) compared to H. pylori(-) children. H. pylori infection was not accompanied by significant changes in markers of bone metabolism in children, although vitamin B12 levels were decreased. Further studies are required to clarify whether H. pylori infection causes time-dependent changes in bone turnover markers during the long course of this inflammatory disease.

Insulin resistance in children with Helicobacter pylori infection

We aimed at investigating insulin resistance in children with Helicobacter pylori (H. pylori) infection. Fasting serum insulin and glucose levels were determined in 31 children with H. pylori (+) (H. pylori-infected group, 20 girls and 11 boys, median age 12 yr, range 6-17) and 29 H. pylori (-) (control group, 18 girls and 11 boys, median age 13 yr, range 5-16). Insulin resistance was assessed using homeostasis model assessment of insulin resistance (HOMA-IR) score. Fasting serum glucose levels did not differ significantly between H. pylori (+) and (-) children. Both HOMA-IR score and serum insulin levels were significantly higher in H. pylori-infected compared to control children. The findings of the present study suggested that there is a certain relation between H. pylori infection and insulin resistance in children.

Construction of an oral recombinant DNA vaccine from H pylori neutrophil activating protein and its immunogenicity

AIM: To construct a live attenuated Salmonella typhimurium (S. typhimurium) strain harboring the H pylori neutrophil activating protein (HP-NAP) gene as an oral recombinant DNA vaccine, and to evaluate its immunogenicity.

METHODS: By genetic engineering methods, the genomic DNA of H pylori was extracted as a template. The total length of the HP-NAP gene was amplified by polymerase chain reaction (PCR) and cloned into pBT vector for sequencing and BLAST analysis, then subcloned into a eukaryotic expression vector pIRES followed by PCR identification and restriction enzyme digestion. The identified recombinant plasmid pIRES-NAP was transfected into COS-7 cells for target fusion protein expression, and its antigenicity was detected by Western blotting. Then the recombinant plasmid was transformed into a live attenuated S. typhimurium strain SL7207 as an oral vaccine strain, and its immunogenicity was evaluated with animal experiments.

RESULTS: A 435 bp product was cloned using high homology with HP-NAP gene in GenBank (more than 98%). With identification by PCR and restriction enzyme digestion, a recombinant eukaryotic expression plasmid pIRES-NAP containing the HP-NAP gene of H pylori was successfully constructed. The expressed target protein had a specific reaction with H pylorii whole cell antibody and showed a single strip result detected by Western blotting. Oral immunization of mice with recombinant DNA vaccine strain SL7207 (pIRES-NAP) also induced a specific immune response.

CONCLUSION: The successful construction of HP-NAP oral DNA vaccine with good immunogenicity may help to further investigate its immunoprotection effects and develop vaccine against H pylori infection.

The best method of detecting prior Helicobacter pylori infection

AIM

Prior Helicobacter pylori (H pylori) infection has often been underestimated. These underestimations have misled physicians attempting to determine the significance between H pylori and certain gastrointestinal lesions such as intestinal metaplasia, atrophic gastritis, and gastric cancer. Our study endeavored to detect past H pylori infections accurately, easily, and rapidly with the newly developed immunoblot kit, Helico Blot 2.1.

METHODS

Thirty-three patients, including 25 H pylori infected and 8 uninfected cases, were enrolled in our study. All patients received consecutive gastroendoscopic examinations and (13)C-urea breath test (UBT) tests at 6- or 12-mo intervals for up to 4 years. Serum samples were obtained from each patient at the same time. Intragastric H pylori infection was confirmed in accordance with the gold standard. Twenty-five H pylori-infected patients received triple therapies after initial bacterial confirmation, and were successful in eradicating their infections. Serially obtained sera were tested by means of Helico Blot 2.1.

RESULTS

Current infection marker detected by Helico Blot 2.1 was unreliable for representing ongoing H pylori infection. Only 35 and 37 ku antibodies of H pylori had significant seroconversion rates 1 year after having been cured. The seropositive rates of 116 ku (cytotoxin-associated antigen (CagA)) and Helico Blot 2.1 were nearly 100% during 4-year follow-up period. Both CagA antigen and Helico blot 2.1 could serve as indicators of long-term H pylori infection.

CONCLUSION

Helico Blot 2.1 can detect past H pylori infections for up to 4 years, and is the best method to date for detecting previous long-term H pylori infection.

Expression patterns of transforming growth factor-beta and its receptors in gastric mucosa of patients with refractory gastric ulcer

AIM: Transforming growth factor-β (TGF-β) plays a regulatory role in tissue repair. In a previous study, we found that TGF-β and its receptors were expressed in gastric mucosa of patients with well-healed gastric ulcers, as demonstrated by immunohistochemistry. To further characterize the role of TGF-β and its receptors in repairing gastric ulcers, we investigated the expression patterns of TGF-β and its receptors in gastric mucosa by in situ hybridization and reverse transcriptase-polymerase chain reaction (RT-PCR).

METHODS: Seventy-four patients with endoscopically proven gastric ulcers were eligible for participation in this study. All patients had routine biopsies on initial endoscopy and were then treated for 12 wk with an H2 blocker. Repeat endoscopy was then performed. There were 8 patients with poorly healed ulcers, and biopsies were taken from the margin of the residual ulcers. These tissue samples, along with biopsy of gastric mucosa near the original ulcers from 8 randomly selected patients with well-healed ulcers were examined for TGF-β and TGF-β receptor II mRNA by RT-PCR and in situ hybridization, as well as immunohistochemistry.

RESULTS: TGF-β and TGF-β receptor II were strongly expressed in tissues from patients with well-healed ulcers. Four of the 8 patients with poor healing had low or absent expression of TGF-β or TGF-β receptor II mRNA. All cases positive by RT-PCR assay were confirmed by in situ hybridization as well as immunohistochemistry.

CONCLUSION: It is suggested that TGF-β and its receptors are important for gastric ulcer healing. These results may have implications for further investigation of the healing process and in predicting response to therapy.

Duodenal alkaline secretion: its mechanisms and role in mucosal protection against gastric acid

Duodenal mucosa, especially its proximal portion, is exposed to intermittent pulses of gastric acid (H+). This review summarises the mechanisms of duodenal bicarbonate (HCO3-) secretion and their role in protecting duodenal epithelium against gastric H+. Duodenal epithelium is a leaky barrier against gastric H+, which diffuses into duodenocytes, but fails to damage them due to: (a) an enhanced expression of cyclooxygenase, producing protective prostaglandins and expression of nitric oxide synthase, releasing nitric oxide, both stimulating duodenal HCO3- secretion and (b) the release of several neurotransmitters also stimulating HCO3- secretion such as vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, acetylcholine and melatonin. At the apical duodenocyte membrane, several HCO3-/Cl- anion exchangers operate in response to luminal H+ to extrude HCO3- into duodenal lumen. In baso-lateral duodenocyte membrane, both non-electrogenic and electrogenic Na+-HCO3- cotransporters are activated after exposure of duodenum to gastric H+, causing inward movement of HCO3- from extracellular fluid to duodenocytes. There are also at least three Na+/H+ exchangers, eliminating H+ which diffused into these cells. The Helicobacter pylori infection with gastric metaplasia in the duodenum and bacterium inoculation results in the inhibition of HCO3- secretion by its endogenous inhibitor dimethyl arginine, resulting in ulcerogenesis.

Expression of Helicobacter pylori Hsp60 protein and its immunogenicity

AIM: To express Hsp60 protein of H pylori by a constructed vector and to evaluate its immunogenicity.

METHODS: Hsp60 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+), which was transformed into BL21 (DE3) E.coli strain to express recombinant protein. Immunogenicity of expressed Hsp60 protein was evaluated with animal experiments.

RESULTS: DNA sequence analysis showed Hsp60 DNA was the same as GenBank’s research. Hsp60 recombinant protein accounted for 27.2% of the total bacterial protein, and could be recognized by the serum from H pylori infected patients and Balb/c mice immunized with Hsp60 itself.

CONCLUSION: Hsp60 recombinant protein might become a potential vaccine for controlling and treating H pylori infection.

Quantitative assessment of motility-associated changes in gastric and duodenal luminal pH in humans

BACKGROUND

Interdigestive pain relieved by food is a common feature of ulcer disease. We tested the hypothesis that the duodenal bulb is intermittently acidified in association with phase III of the interdigestive motility cycle, and tried to quantify the balance between acid and duodenal bicarbonate secretion during this particular period.

METHODS

The experiments were performed in Helicobacter-negative healthy volunteers. Gastric and duodenal luminal pH was measured with a triple antimon electrode before, during, and after phase III of the migrating motor complex. Gastric acid secretion rate was measured in real time with a perfusion system and duodenal bicarbonate secretion was estimated from a continuous recording of the transmucosal potential difference (PD) in the duodenal bulb.

RESULTS

No significant changes in bulb pH occurred before, during, or after phase III. During the studied time window, the stomach produced 2.24 +/- 0.55 mmol of acid at a peak pH of 1.74 +/- 0.10. Basal HCO3- secretion calculated from bulb PD was 0.82 +/- 0.12 mmol x 30 min(-1) to which was added 0.47 +/- 0.07 mmol of HCO3- during duodenal phase III. The contribution of retroperistalsis-driven HCO3- reflux was small (0.08 +/- 0.02 mmol).

CONCLUSIONS

Both the pH recording and the quantitative assessment of secretion rates show that in healthy subjects, fasting gastric acid production and duodenal bicarbonate secretion are of similar magnitude and dynamically coordinated. The mechanism behind the linkage may be reflex activation by motor activity, or a luminal PCO2 rise during phase III activity.