Helicobacter pylori: the primary cause of duodenal ulceration or a secondary infection?

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.

Gallstones and Concomitant Gastric Helicobacter pylori Infection

Background. The association of gallstones with Helicobacter pylori has been investigated but not clearly demonstrated. In this study, the presence of H. pylori in the gallbladder mucosa of patients with symptomatic gallstones was investigated. Method. Ninety-four consecutive patients with symptomatic gallstone disease were enrolled for the study. Gastroscopy and gastric H. pylori urease test were done before cholecystectomy to all patients who accepted. After cholecystectomy, the gallbladder tissue was investigated in terms of H. pylori by urease test, Giemsa, and immunohistochemical stain. Results. Overall 35 patients (37%) gallbladder mucosa tested positive for H. pylori with any of the three tests. Correlation of the three tests Giemsa, IHC, and rapid urease test was significant (r_s: 0590, P > 0.001). Rapid urease test was positive in the gastric mucosa in 47 (58.7%) patients, and it was positive in the gallbladder mucosa in 21 patients (22%). In 15 patients both gastric and gallbladder tested positive with the urease test. There was significant correlation of rapid urease test in both of gallbladder and gastric mucosa (P = 0.0001). Conclusion. Study demonstrates the presence of H. pylori in the gallbladders of 37% of patients with symptomatic gallstones.

Is Helicobacter pylori Infection the Primary Cause of Duodenal Ulceration or a Secondary Factor? A Review of the Evidence

Helicobacter pylori (H. pylori) has a role in the multifactorial etiology of peptic ulcer disease. A link between H. pylori infection and duodenal ulcer disease is now established. Other contributing factors and their interaction with the organism may initiate the ulcerative process. The fact that eradication of H. pylori infection leads to a long-term cure in the majority of duodenal ulcer patients and the fact that the prevalence of infection is higher in ulcer patients than in the normal population are cogent arguments in favor of it being the primary cause of the ulceration. Against this concept there are issues that need explanation such as the reason why only a minority of infected persons develop duodenal ulceration when infection with H. pylori is widespread. There is evidence that H. pylori infection has been prevalent for several centuries, yet duodenal ulceration became common at the beginning of the twentieth century. The prevalence of duodenal ulceration is not higher in countries with a high prevalence of H. pylori infection. This paper debate puts forth the point of view of two groups of workers in this field whether H. pylori infection is the primary cause of duodenal ulcer disease or a secondary factor.

Is Helicobacter pylori good or bad?

Helicobacter pylori remains a controversial organism with regards to humans, with its epidemiology still being unclear nearly two decades after its discovery. The association between H. pylori infection and subsequent development of chronic active gastritis, peptic ulcer disease, gastric cell carcinoma, and B cell mucosa-associated lymphoid tissue (MALT) lymphoma has been well established. Current studies, however, suggest that fewer than 20 % of all infected patients will develop any consequences from their infection. Hence, should the infection be considered a disease not at all or, on the contrary, is the microorganism harmful in only some circumstances? This article attempts to weigh the currently available evidence supporting that H. pylori may be good and not always bad.

A tribute to Dr. Frank I Tovey on his 90th birthday

This paper pays a tribute to Dr. Frank I Tovey on his 90th birthday which happens on September 1, 2011, and briefly describes the major findings in his research career and contributions as follows. The geographical prevalence of duodenal ulceration is related to staple diets. Unrefined wheat and maize, soya, certain pulses and millets are associated with a low prevalence while refined wheat, maize and rice, yams, cassava and green banana with a high prevalence. Predominant foodstuffs from low prevalence areas are ulceroprotective in rat peptic ulcer models. The protective activity lies in the lipid fraction present in these foodstuffs. The lipid fraction also promotes ulcer healing, is active both orally and intramuscularly and is ulceroprotective against non-steroidal anti-inflammatory drugs (NSAIDs). The phospholipids and phytosterols present in the lipid have been identified to be responsible for this protective activity. The combination of phospholipids and phytosterols may be of value in the prevention and treatment of duodenal ulceration and protection against the ulcerogenic effect of NSAIDs.

Dietary Phytosterols Protective Against Peptic Ulceration

BACKGROUND

In developing countries the prevalence of duodenal ulceration is related to the staple diet and not to the prevalence of Helicobacter pylori. Experiments using animal peptic ulcer models show that the lipid fraction in foods from the staple diets of low prevalence areas gives protection against ulceration, including ulceration due to non-steroidal anti-inflammatory drugs (NSAIDs), and also promotes healing of ulceration. The lipid from the pulse Dolichos biflorus (Horse gram) was highly active and used for further investigations. Further experiments showed the phospholipids, sterol esters and sterols present in Horse gram lipid were gastroprotective. Dietary phospholipids are known to be protective, but the nature of protective sterols in staple diets is not known. The present research investigates the nature of the protective phytosterols.

METHODS

Sterol fractions were extracted from the lipid in Dolichos biflorus and tested for gastroprotection using the rat ethanol model. The fractions showing protective activity were isolated and identification of the components was investigated by Gas Chromatography-Mass Spectrometry (GC-MS).

RESULTS

The protective phytosterol fraction was shown to consist of stigmasterol, β-sitosterol and a third as yet unidentified sterol, isomeric with β-sitosterol.

CONCLUSIONS

Dietary changes, affecting the intake of protective phospholipids and phytosterols, may reduce the prevalence of duodenal ulceration in areas of high prevalence and may reduce the incidence of recurrent duodenal ulceration after healing and elimination of Helicobacter pylori infection. A combination of phospholipids and phytosterols, such as found in the lipid fraction of ulceroprotecive foods, may be of value in giving protection against the ulcerogenic effect of NSAIDs.

Helicobacter pylori negative, non-steroidal anti-inflammatory drug-negative peptic ulcers in India

INTRODUCTION

The past decade has witnessed a global rise in the prevalence of peptic ulcer disease which is unrelated to non-steroidal anti-inflammatory drugs (NSAIDs) or Helicobacter pylori infection. Although initially recognized in the West, this disease is being increasingly recognized in the Asian population. The higher risk of bleeding and ulcer recurrence in this subgroup of patients highlights the clinical importance of analyzing the changing trends of peptic ulcer disease in developing countries.

AIMS

To assess the proportion of non-NSAID, non-H. pylori peptic ulcer disease in an Indian cohort of patients with peptic ulcer disease managed at a tertiary care center; and to compare the gastric and duodenal ulcer subgroups in these patients.

METHODS

Patients diagnosed with peptic ulcer disease were screened for a history of NSAID use and those with a negative history were tested for H. pylori using a combination of rapid urease test (RUT) and (14)C-urea breath test (UBT). Only those cases which tested negative for both the tests were considered 'H. pylori-negative'. Serum gastrin was measured in all patients included in the study.

RESULTS

Seventy-four gastric ulcer (GU) and 54 duodenal ulcer (DU) patients with no history of NSAID use were enrolled. Of these, 36 GU (45.9%) and 16 DU (29.6%) patients were H. pylori-negative. The proportion of non-NSAID non-H. pylori gastric ulcers was significantly higher than duodenal ulcers (p < 0.05). However, patients who tested negative for H. pylori did not differ significantly from those who tested positive with regard to age, gender, serum gastrin level, and presence of risk factors, like smoking and alcoholism.

CONCLUSION

The current study indicates existence of high proportion of non-NSAID, non-H. pylori peptic ulcer disease in Indian patients.

Dominant negative p38 mitogen-activated protein kinase expression inhibits NF-kappaB activation in AR42J cells

BACKGROUND

The role of the p38 mitogen-activated protein (MAP) kinase in acute pancreatitis pathogenesis is controversial. We hypothesize that p38 plays a role in regulating NF-kappaB activation in exocrine pancreatic cells.

METHODS

AR42J cells incorporating an NF-kappaB-responsive luciferase reporter, with and without adenoviral transduction of DNp38, were stimulated with cholecystokinin (CCK) or tumor necrosis factor-alpha (TNF-alpha) prior to measuring NF-kappaB activation.

RESULTS

CCK- or TNF-alpha-stimulated NF-kappaB-dependent gene transcription (luciferase assay) was substantially subdued by DNp38 expression. These findings were confirmed by electrophoretic mobility shift assay. Nuclear translocation of the p65 NF-kappaB subunit following agonist stimulation was evident (supershift). Characterization studies showed excellent adenoviral infection efficiency and cell viability in our AR42J cell model. Agonist-stimulated dose- and time-dependent p38 activation, with inhibition by DNp38 expression, was also confirmed.

CONCLUSION

The p38 MAP kinase regulates NF-kappaB pathway activation in exocrine pancreatic cells, and thus potentially plays a role in the mechanism of acute pancreatitis pathogenesis..

Enteral exclusion increases MAP kinase activation and cytokine production in a model of gallstone pancreatitis

BACKGROUND

We have previously demonstrated that enteral exclusion augments pancreatic p38 mitogen-activated protein (MAP) kinase activation and tumor necrosis factor-alpha (TNF-alpha) production after bile-pancreatic duct ligation in rats.

METHODS

In the present study, we evaluated c-Jun NH(2)-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) activation, and cytokine production, in pancreata of duct-ligated rats with and without duodenal bile-pancreatic juice replacement from a donor rat. We hypothesized that enteral exclusion of bile-pancreatic juice activates stress kinases and induces cytokine production in ligation-induced acute pancreatitis.

RESULTS

Increased JNK and ERK activation after ligation are inhibited by bile-pancreatic juice replacement. Increases in pancreatic production of IL-1beta and IL-12 after ligation are significantly subdued by replacement. In additional in vitro studies, we show that cholecystokinin- or TNF-alpha-stimulated nuclear transcription factor kappa-B activation in AR42J cells is inhibited by dominant negative ERK2.

CONCLUSIONS

Our novel findings using our Donor Rat Model indicate that bile-pancreatic juice exclusion induces MAP kinase activation and exacerbates cell stress and inflammation in this experimental model of gallstone pancreatitis. and IAP.

Bile-pancreatic juice exclusion increases p38MAPK activation and TNF-alpha production in ligation-induced acute pancreatitis in rats

Acute pancreatitis is associated with stress kinase activation and cytokine production. We hypothesize that bile-pancreatic juice exclusion activates p38(MAPK) and induces TNF-alpha production in ligation-induced acute pancreatitis. We compared rats with 1-3 h of duct ligation, duct ligation with duodenal bile-pancreatic juice replacement from a donor rat, and sham operation. Pancreatic homogenates were analyzed as follows: (a) Immunoblots using phospho-specific p38(MAPK) antibody showed increased p38(MAPK) activation after ligation that was inhibited by bile-pancreatic juice replacement. (b) Immune-complex kinase assay using ATF-2 as substrate showed increased p38(MAPK) activation after ligation that was subdued by bile-pancreatic juice replacement. (c) ELISA showed increased pancreatic TNF-alpha production after ligation that was significantly ameliorated by bile-pancreatic juice replacement.

CONCLUSION

Bile-pancreatic juice exclusion from gut increases p38(MAPK) activation and TNF-alpha production in this experimental model. Our findings support our central hypothesis that bile-pancreatic juice exclusion exacerbates cell stress and acute inflammation in ligation-induced acute pancreatitis.

Sequence diversity analysis of CagA gene and corresponding protein in Helicobacter pylori

AIM: To find the structural characteristics and correlation with region and the clinical outcomes by analyzing nucleotide and amino acid sequences of CagA, our research results and data of CagA sequences deposited in NCBI database.

METHODS: The characteristics of CagA sequences were analyzed, and a phylogenetic tree was constructed by using Vector NTI Suite 9.0, ClastalX (version 1.8), Phylip (version 3.5) and Treeview (version 1.61).

RESULTS: Through searching NCBI nucleotide and protein database, we obtained 44 complete and 560 partial CagA sequences. Aligning these sequences, analyzing similarity and constructing phylogenetic tree, we found CagA seqenceses could be classified into two types: western type and eastern type. Analyzing the CagA C terminal of 44 complete and 266 partial sequences, we classified the repeat sequence of CagA C terminal into two types: type I was discontinuous repeat sequence, common among all the strains, and type II was continuous repeat sequence, found in some individual strains. The type II repeat sequence was found in 31% (12/39) of strains from gastric cancer patients, compared with 13% (9/71) of strains from non-cancer patients (P = 0.021 < 0.05). Strains with the type II repeat sequence were associated with gastric cancer.

CONCLUSION: There is a high diversity of CagA nucleotide and amino acid sequences among H. pylori strains, showing a distinct geographic character as western and eastern region collection. The repeat sequence of CagA C terminal can be classified into two types, and strains with the type II repeat sequence containing EPIYA motif exhibits a stronger pathogenecity.

Dynamic changes of gastric mucosal pathology after clearance of Helico-bacter pylori infection

AIM: To investigate the characteristics of pathological changes in the gastric mucosa after anti-Helicobacter pylori (H. pylori ) therapy.

METHODS: The samples were obtained through electronic gastroscope or operation and divided into two groups: therapy group (n = 32) in which the patients received standard anti-H. pylori therapy; and control group (n = 25) without anti-H. pylori therapy. Histological examinations were carried out after gastroscopic inspection or operation, half a year and one year later.

RESULTS: H. pylori in the mucous membrane of the stomach in all 32 cases in therapy group diminished or disappeared and pathological changes (inflammation, intestinal metaplasia and dysplasia) attenuated to some extent. There were significant differences between samples at different time points of examination (P < 0.05). In all 25 cases in group control, changes of H. pylori and pathology of the mucous membrane were not apparent. There was not a stalistical significance between samples at different time points of examination (P > 0.05). There was significant difference between samples of therapy and control groups (P < 0.05).

CONCLUSION: Anti-H. pylori therapy has active significance for the improvement of pathological changes in the mucous membrane of the stomach.

CCK-A receptor induction and P38 and NF-kappaB activation in acute pancreatitis

Bile-pancreatic duct ligation in rats excludes bile-pancreatic juice from the gut and induces acute pancreatitis. Bile-pancreatic juice exclusion from the gut results in increased plasma cholecystokinin (CCK) levels. CCK-A receptor-mediated exocrine pancreatic hyperstimulation is implicated in disease pathogenesis. In the present study, we show for the first time a progressive rise in CCK-A receptor protein expression in ligation-induced acute pancreatitis in rats. As CCK-A receptor induction could amplify CCK-mediated acinar hyperstimulation and exacerbate acinar cell stress with activation of the p38(MAPK) stress kinase pathway, we studied CCK-A receptor protein expression and p38(MAPK) activation in duct ligation-induced acute pancreatitis in rats. Compared to sham-operated controls, acute pancreatitis induced by bile-pancreatic duct ligation associates with a temporal increase in pancreatic CCK-A receptor protein expression, p38(MAPK) expression and activation, and NF-kappaB activation. These findings may have significance in the mechanism of disease pathogenesis in this experimental model.

Trends in peptic ulcer pharmacotherapy

Considering the diseases of the stomach and duodenum, peptic ulcer has been the one with a significant clinical impact. The pathophysiology of peptic ulcer has centred on an imbalance between aggressive and protective factors. The discovery of Helicobacter pylori as a cause of peptic ulcer has changed our approach greatly towards this disease. Despite the decreasing frequency of H. pylori-induced peptic ulcers, peptic ulcer remains a major clinical problem partly because nonsteroidal anti-inflammatory drug (NSAID)-related ulcers and hospital admissions for ulcer complications associated with NSAIDs have increased in frequency. The interaction between H. pylori and NSAIDs is one of the most controversial issues in peptic ulcer. In this article, current concepts of peptic ulcer etiopathogenesis and the management of peptic ulcer according to the etiology were reviewed.

Influence of H. pylori on cyclinD1 and PCNA mRNA expression in HepG2 cell line

AIM: To observe the effects of Helicobacter pylori (H. pylori) on cyclinD1 and PCNA mRNA expression in a human hepatoma cell line HepG2.

METHODS: H. pylori was co-cultured with HepG2 for 1, 3,6, 12 and 24 h. The cyclinD1 and PCNA mRNA expression was detected by semi-quantitative RT-PCR.

RESULTS: When HepG2 cells were cocultured with H. pylori CagA⁺ strain, the amount of cyclinD1 mRNA was increased 4.0-fold by 3 h and PCNA mRNA was increased 2.0-fold by 6 h, compared with that of uninfected control. Neither cyclinD1 mRNA nor PCNA mRNA of the HepG2 cells was increased after incubation with H. pylori CagA^- strain.

CONCLUSION: H. pylori can induce increasing expression of cyclinD1 and PCNA mRNA in HepG2, which may play some roles in the development of hepatocellular carcinoma.

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.

Cloning, sequencing and bioinformatics analysis of adhesin gene babA2 of Helicobacter pylori

AIM

To obtain DNA of human Helicobacter pylori (Hp) adhesin gene babA₂ and the amplified fragment was inserted into plasmid pET-22b (+) for nucleotide sequencing analysis and to carry out bioinformatics analysis.

METHODS

The babA₂ DNA was amplified by PCR and inserted into the plasmid pET -22b (+) and sequenced. The biological property was analysed by the software ANTHEPROT V4.3c.

RESULTS

DNA sequencing analysis showed that the sequence of babA₂ DNA was the same as that published by GenBank. ANTHEPROT V4.3c software predicted its relative molecular mass(M_r) was 78 kD and it possessed good antigencity and hydrophobicity.

CONCLUSION

A confirmed babA₂ gene has been obtained and bioinformatics analysis showed that it had good immunogenicity. Our study lays a good foundation for recombination, expression and relevant research on adhesin gene babA2 of Helicobacter pylori.

Recombinant Helicobacter pylori catalase

AIM: To construct a recombinant strain which highly expresses catalase of Helicobacter pylori (H. pylori) and assay the activity of H. pylori catalase.

METHODS: The catalase DNA was amplified from H. pylori chromosomal DNA with PCR techniques and inserted into the prokaryotie expression vector pET-22b (+), and then was transformed into the BL21 (DE3) E. coli strain which expressed catalase recombinant protein. The activity of H. pylori catalase was assayed by the Beers&Sizers.

RESULTS: DNA sequence analysis showed that the sequence of catalase DNA was the same as GenBank’s research. The catalase recombinant protein amounted to 24.4% of the total bacterial protein after induced with IPTG for 3 hours at 37 °C and the activity of H. pylori catalase was high in the BL21 (DE3) E. coli strain.

CONCLUSION: A clone expressing high activity H. pylori catalase is obtained, laying a good foundation for further studies.

Modalities of testing Helicobacter pylori in patients with nonmalignant bile duct diseases

AIM: This paper describes the procedure of detection of Helicobacter pylori (H. pylori ) in bile specimens in patients suffering frombenign diseases of biliary ducts (lithiasis with/without nonspecific cholangitis).

METHODS: The group of 72 patients entering the study consisted of 32 male and 40 female (45% and 55%, respectively). Bile was obtained during ERCP in 68 patients, and during cholecystectomy in 4 patients. A fast urease test (FUT) to determine the existence of H. pylori in gastric mucosa was carried out for all the patients during the endoscopic examination. The existence of genetic material of H. pylori was determined by detection of ureA gene by the method of nested PCR. The results of this reaction were shown by electrophoresis on 10 g•L⁻¹ agarose gel in a band of 256 bp.

RESULTS: The majority of the patients included in our study had biliary lithiasis without signs of cholangitis (48 patients, 67%), whereas other patients were complicated by cholangitis (17 patients, 24%). Seven patients (9%) had normal ERCP, forming thus the control group. In the group of patients with lithiasis 26 patients (54.2%) had positive PCR of H. pylori in bile and among the patients with associated cholangitis positive PCR was detected in 9 patients (52.9%). Among the seven patients with normal ERCP only one (14%) had positive PCR of H. pylori. A high percentage of H. pylori infection of gastric mucosa was observed (57 patients, 79%). It was also observed that its slightly higher positivity was in the patients with distinct bile pathology: 81% FUT positive patients in the group with choledocholithiasis alone and 76% in the group with choledocholithiasis associated with cholangitis. Seventy-one percent of the patients with regular findings had positive FUT.

CONCLUSION: The prevalence of H. pylori infection both in bile and in gastric mucosa in patients with benign diseases of biliary ducts does not show a statistically significant difference in relation to the prevalence of the same with the patients with normal ERCP. The existence of H. pylori infection possibly does not play a role in pathogenesis of benign biliary diseases.

Clinical application of serial operations with preserving spleen

AIM: To evaluate the clinical application of serial operations with preservation of spleen.

METHODS: Serial operations with preserving spleen were performed on 211 cases in our hospital from 1980 to 2000. The patient’s age ranged from 13 to 56 years, averaging 38 years. Diseases included splenic injury in 171 cases, portal hypertension in 9 cases, splenic cyst in 10 cases, and the lesion of pancreatic body and tail in 21 cases.

RESULTS: All the cases were cured, and 129 patients were followe dup from 3 mo to 3 years with the leukocyte phagocytosis test, detection of immunoglubin, CT, ^99mTc scanning and ultrasonography. The results were satisfactory.

CONCLUSION: The operations with preserving spleen were safe, feasible, and worth of clinical application.