Influence of IL-1 gene cluster polymorphisms on the development of H. pylori associated gastric ulcer

BACKGROUND AND AIMS: Chronic H. pylori infection is the main cause of ulcer disease which depicts a major burden of our healthy care systems. The individual host immune response plays a pivotal role in the outcome of the infection but genetic susceptibility to develop gastric ulcer is unknown. IL-1beta and its natural receptor antagonist IL-1ra are involved in the inflammatory response to H. pylori infection. Thus, we investigated the influence of functional genetic variants in the IL-1 gene cluster on the development of gastric ulcer disease. PATIENTS AND METHODS: 390 H. pylori infected patients were genotyped for IL-1B -31 and +3954 by TaqMan technology. Alleles of IL-1RN 86VNTR were determined by gel electrophoresis after amplification. Three hundred and sixty healthy blood donors were included as healthy controls. RESULTS: Carriage of the IL-1B -31 C allele conferred a increased but not significant risk for H. pylori infection (OR: 1.3, Wald 95% CI: 0.8相似文献   

Role of the host in pathogenesis of Helicobacter-associated gastritis: H. felis infection of inbred and congenic mouse strains.

In humans, Helicobacter pylori establishes a chronic infection which can result in various degrees of gastric inflammation, peptic ulcer disease, and a predisposition to gastric cancer. It has been suggested that bacterial virulence factors such as the vacuolating toxin (VacA) and the cytotoxin-associated gene product (CagA) may play a major role in determining the clinical outcome of Helicobacter infections. The role of host responses in these varied outcomes has received little attention. Helicobacter felis, which does not express CagA or VacA, causes chronic infection and inflammation in a well-characterized mouse model. We have used this model to evaluate the role of host responses in Helicobacter infections. BALB/c, C3H, and C57BL/6 mice were orally infected with a single strain of H. felis, and 2 and 11 weeks after infection, the mice were sacrificed and evaluated histologically for magnitude of H. felis infection. Intensity and extent of inflammation, and cellular composition of the inflammatory infiltrate. All three strains of mice demonstrated comparable levels of infection at 11 weeks, but the pattern and intensity of inflammation varied from minimal in BALB/c mice to severe in C57BL/6 mice. Gastric epithelial erosions were noted in C3H mice, and mucous cell hyperplasia was observed in C3H and C57BL/6 mice. Abundant mucosal mast cells were observed in the gastric tissues of all three mouse strains. Studies using major histocompatibility complex (MHC)-congenic mice revealed probable contributions by both MHC and non-MHC genes to Helicobacter-induced inflammation. Thus, large variations in the severity of disease were observed after infection of different inbred strains and congenic mice with a single isolate of H. felis. These results demonstrate the importance of the host response in disease outcome following gastric Helicobacter infection.     

dupA polymorphisms and risk of Helicobacter pylori-associated diseases

The dupA of Helicobacter pylori has been suggested as a virulence marker associated with the development of duodenal ulcer disease. However, the studies performed in different geographical areas have shown that there are variations in the prevalence of dupA and its association with H. pylori clinical outcomes. Our group did not observe associations between the presence of dupA and H. pylori clinical outcomes in Brazil. On the other hand, we observed 2 mutations in the sequence of dupA that lead to stop codons: a deletion of an adenine at position 1311 and an insertion of an adenine at position 1426 of the gene. Our aim was to evaluate associations of the presence of dupA with duodenal ulcer and gastric cancer, considering dupA-positive only those H. pylori strains that do not have the mutations in the gene sequence. We also evaluated the effect of infection with a strain carrying an intact dupA on the gastric mucosa histology and IL-8 gastric levels. Colonization with strains that had the intact dupA was negatively associated with gastric carcinoma (p=0.001, OR=0.32, 95% CI=0.16-0.66). The presence of dupA was also associated with an increased degree of antral mucosa inflammation (p=0.01) and with decreased corpus atrophy (p<0.01) as well as with increased gastric mucosa IL-8 levels (p=0.04). In conclusion, the infection with a H. pylori strain containing the dupA without the stop codon polymorphisms is associated with a lower risk of development of gastric carcinoma in Brazilian subjects.     

The comparison of histologic gastritis in patients with duodenal ulcer, chronic gastritis, gastric ulcer and gastric cancer

This study was designed to investigate the differences of histologic gastritis according to the endoscopic diagnosis, and between H. pylori positive and negative gastritis, using the Sydney system. A total of 122 patients (42 duodenal ulcer, 31 chronic gastritis, 35 gastric ulcer and 14 gastric cancer) underwent endoscopy with biopsies from the antrum and body. Among the 122 patients, 104 (85%) were H. pylori positive. H. pylori density of the antrum was significantly higher in duodenal ulcer than in chronic gastritis, gastric ulcer, and gastric cancer. The positivity of intestinal metaplasia was lowest in duodenal ulcer and highest in gastric cancer. H. pylori density as well as grade of activity, inflammation and atrophy were significantly higher in the antrum than in the body in duodenal ulcer, while in chronic gastritis, gastric ulcer and gastric cancer there was no difference of H. pylori density, activity, inflammation and atrophy between the antrum and body. The grade of activity and chronic inflammation were significantly higher in H. pylori positive patients than in H. pylori negative patients in both the antrum and body. In conclusion, the gastritis of duodenal ulcer was mainly localized to the antrum, while the gastritis of chronic gastritis, gastric ulcer or gastric cancer was rather uniform in the antrum and body. H. pylori seemed to be related to the development of chronic inflammation and activity.     

Sequence variation, linkage disequilibrium and association with Crohn's disease on chromosome 5q31

Chromosome 5q31 contains a cluster of genes involved in immune response, including a 250 kb risk haplotype associated with Crohn's disease (CD) susceptibility. Recently, two functional variants in SLC22A4 and SLC22A5 (L503F and G-207C), encoding the cation transporters OCTN1 and OCTN2, were proposed as causal variants for CD, but with conflicting genetic evidence regarding their contribution. We investigated this locus by resequencing the coding regions of 10 genes in 24 CD cases and deriving a linkage disequilibrium (LD) map of the 27 single nucleotide polymorphisms (SNPs) detected. Ten SNPs representative of the LD groups observed, were tested for CD association. L503F in SLC22A4 was the only nonsynonymous SNP significantly associated with CD (P=0.003), but was not associated with disease in the absence of other markers of the 250 kb risk haplotype. Two other SNPs, rs11242115 in IRF1 and rs17166050 in RAD50, lying outside the 250 kb risk haplotype, also showed CD association (P=0.019 and P=0.0080, respectively). The RAD50 gene contains a locus control region regulating expression of the Th2 cytokine genes at this locus. Other as yet undiscovered SNPs in this region may therefore modulate gene expression and contribute to the risk of CD, and perhaps of other inflammatory phenotypes.     

Treatment of H. pylori infected mice with antioxidant astaxanthin reduces gastric inflammation, bacterial load and modulates cytokine release by splenocytes

Helicobacter pylori is a gram-negative bacterium affecting about half of the world population, causing chronic gastritis type B dominated by activated phagocytes. In some patients the disease evolves into gastric ulcer, duodenal ulcer, gastric cancer or MALT lymphoma. The pathogenesis is in part caused by the immunological response. In mouse models and in human disease, the mucosal immune response is characterized by activated phagocytes. Mucosal T-lymphocytes are producing IFN-gamma thus increasing mucosal inflammation and mucosal damage. A low dietary intake of antioxidants such as carotenoids and vitamin C may be an important factor for acquisition of H. pylori by humans. Dietary antioxidants may also affect both acquisition of the infection and the bacterial load of H. pylori infected mice. Antioxidants, including carotenoids, have anti-inflammatory effects. The aim of the present study was to investigate whether dietary antoxidant induced modulation of H. pylori in mice affected the cytokines produced by H. pylori specific T-cells. We found that treatment of H. pylori infected mice with an algal cell extract containing the antioxidant astaxanthin reduces bacterial load and gastric inflammation. These changes are associated with a shift of the T-lymphocyte response from a predominant Th1-response dominated by IFN-gamma to a Th1/Th2-response with IFN-gamma and IL-4. To our knowledge, a switch from a Th1-response to a mixed Th1/Th2-response during an ongoing infection has not been reported previously.     

Inflammatory activation of neutrophils by Helicobacter pylori; a mechanism insensitive to pertussis toxin

Chronic active gastritis of the antral mucosa is a characteristic feature of infection with Helicobacter pylori and interactions between bacterial components and inflammatory cells are believed to play an important pathogenic role. Neutrophils stimulated with H. pylori sonicate were demonstrated to release L-selectin (CD62L) expressed on the cellular surface, with a subsequent up-regulation of the beta2-integrins CD11b and CD11c, both in a dose- and time-dependent manner, reaching maximum levels after 45-60 min of stimulation. No changes were observed for the CD11a receptor upon stimulation. The activating properties of H. pylori sonicates on neutrophils were heat-labile and susceptible to protease attack, indicating the protein nature of the activating factor. After size fractionation, the major neutrophil-inducing activity was detected in the high molecular weight fraction exhibiting urease activity. Pertussis toxin was unable to inhibit neutrophil activation by the H. pylori protein(s). We conclude that proteins from H. pylori have a potent inflammatory effect on the surface membrane molecules CD62L, CD11b and CD11c essential for transendothelial migration of neutrophils to areas of inflammation. The neutrophil-activating protein(s) act via a pertussis toxin-insensitive mechanism.     

Macrophages are mediators of gastritis in acute Helicobacter pylori infection in C57BL/6 mice

Helicobacter pylori is the etiological agent of human chronic gastritis, a condition seen as a precursor to the development of gastrointestinal ulcers or gastric cancer. This study utilized the murine model of chronic H. pylori infection to characterize the role of macrophages in the induction of specific immune responses and gastritis and in the control of the bacterial burden following H. pylori infection and vaccination. Drug-loaded liposomes were injected intravenously to deplete macrophages from C57BL/6 mice, and effective removal of CD11b+ cells from the spleens and stomachs of mice was confirmed by immunofluorescence microscopy. Transient elimination of macrophages from C57BL/6 mice during the early period of infection reduced the gastric pathology induced by H. pylori SS1 but did not affect the bacterial load in the stomach. These data suggest that macrophages are important to the severity of gastric inflammation during H. pylori infection.     

Relation between seroreactivity to low-molecular-weight Helicobacter pylori-specific antigens and disease presentation

The identification of Helicobacter pylori-strain specific factors that correlate with clinical outcome has remained elusive. We investigated possible relationships between a group of H. pylori antigens and clinical outcome and compared an immunoblot assay kit (HelicoBlot, version 2.1 [HB 2.1]; Genelabs Diagnostics) with an established serological test, the high-molecular-weight cell-associated protein test (HM-CAP). We used sera from 156 Thai patients with different disease presentations, including 43 patients with gastric cancer, 64 patients with gastric ulcer, and 49 patients with nonulcer dyspepsia (NUD). HB 2.1 was compared to HM-CAP as a diagnostic test for H. pylori infection. The seroprevalence of H. pylori was significantly higher among gastric cancer patients than among patients with NUD (93 and 67%, respectively; P < 0.01). Among the H. pylori-seropositive patients, the presence of the antibody to the 37,000-molecular-weight antigen (37K antigen) was inversely related to the presence of gastric cancer (e.g., for gastric cancer patients compared with NUD patients, odds ratio [OR] = 0.28 and 95% confidence interval [CI] = 0.1 to 0.8). The presence of antibody to the 35K antigen was higher in gastric ulcer patients than in NUD patients (OR = 11.5; 95% CI = 2.4 to 54.3). The disease associations of antibodies to the 35K and 37K antigens are consistent with the possibility that these antigens are either indirect markers for H. pylori-related diseases or have specific active or protective roles in H. pylori-related diseases.     

No allelic variant associations of the IL-1 and TNF gene polymorphisms in the susceptibility to duodenal ulcer disease

Recent studies have reported the association of a pro-inflammatory profile of genetic polymorphisms in IL-1B, IL-1RN, TNF-A, and IL-10 genes with an increased risk of non-cardia gastric cancer. Because gastric cancer and duodenal ulcer are mutually exclusive outcomes of Helicobacter pylori infection, we aimed to investigate possible allelic variant associations of several functional polymorphisms in the IL-1B, IL-1RN, TNFA, and LTA genes in the susceptibility to duodenal ulcer. Genomic DNA from 118 patients with duodenal ulcer and 97 healthy controls was typed for the IL-1B polymorphisms at positions -511, -31, and +3954, the VNTR polymorphism in intron 2 of the IL-1RN gene, the TNFA-308, TNFA -238, and the NcoI and BsI LTA polymorphisms by PCR, SSCP and TaqMan assays. H. pylori infection and non-steroidal anti-inflammatory drugs (NSAIDs) use was investigated in patients and controls. Logistic regression analysis identified H. pylori infection (OR: 12.86; 95%CI: 3.85-43), NSAID use (OR: 11.95; 95%CI: 4.19-34.05), and family history-ulcer (OR: 3.79; 95%CI: 1.68-8.54) as independent risk factors for duodenal ulcer. When the effect of the combinations of IL-1 and TNF genotypes was studied we found that the distribution of all possible combinations of these eight polymorphisms was similar in duodenal ulcer patients and controls. The simultaneous carriage of alleles IL-1RN*2/IL-1B -31T/IL-1B -511C/IL-IB +3954C/TNF-HaplotypeE negative (termed in some studies as 'low-producing' alleles) was increased in H. pylori-positive duodenal ulcer patients compared to H. pylori-infected healthy controls (10.5% vs. 5.9%) although the difference did not reach statistical significance (OR: 1.85; 95%CI: 0.57-5.99, P = 0.41). Moreover, no differences were found with respect to H. pylori status, NSAID use, age, gender, smoking habit, type of complication, recurrence of the ulcer, and need for surgical treatment. Our data show no association between allelic variants of IL-1 and TNF gene polymorphisms in the susceptibility to and final outcome of duodenal ulcer.     

Association of interleukin 1 gene family polymorphisms with duodenal ulcer disease

Cytokine genes taking part in the immunological response to Helicobacter pylori infection are good candidates to study for genetic predisposition to duodenal ulcer disease (DU). Among cytokines, interleukin (IL)-1beta and its natural specific inhibitor, the interleukin-1 receptor antagonist, are cytokines that play a key role in regulating gastric acid secretion and modulating the immune response in the gastrointestinal mucosa. We aimed to investigate whether polymorphisms in the IL-1B and IL-1RN genes are involved in the susceptibility to duodenal ulcer. DNA from 131 unrelated Spanish Caucasian patients with DU and 105 ethnically matched healthy controls was typed for the IL-1B-511, IL-1B-31, and IL-1B + 3954 gene polymorphisms, and the VNTR polymorphism in intron 2 of the IL-1RN gene by polymerase chain reaction (PCR)-based methods and TaqMan assays. H. pylori status and non-steroidal anti-inflammatory drugs (NSAIDs) use was determined in all patients and controls. Logistic regression analysis identified H. pylori infection (OR: 9.74; 95%CI = 3.53-26.89) and NSAIDs use (OR: 8.82; 95%CI = 3.51-22.17) as independent risk factors for DU. In addition, the simultaneous carriage of IL-1RN*2, IL-1B-511*C, IL-1B-31*T and IL-1B + 3954*C alleles was a genetic risk factor for DU in patients with H. pylori infection (OR: 3.22; 95%CI = 1.09-9.47). No significant differences in IL-1RN and IL-1B genotypes were found when patients were categorized according to gender, age of onset, smoking habit, NSAIDs use, type of complication and positive family history. Our results provide further evidence that host genetic factors play a key role in the pathogenesis of duodenal ulcer.     

Helicobacter pylori. Its role in the pathogenesis of peptic ulcer disease in a new animal model.

The association and causative role of Helicobacter pylori infection of the stomach with gastric ulcer, duodenal ulcer, non-ulcer dyspepsia, and gastritis has remained controversial. The authors studied the effects of daily intragastric administration of H. pylori suspension in saline (10(8) CFU/ml) and bacteria-free filtrates of saline H. pylori suspensions in 85 Sprague-Dawley rats (weight, 150 to 200 g) with normal mucosa and with surgically produced experimental gastric ulcers. Group I rats (n = 30) with pre-existent experimental gastric ulcers received H. pylori suspension (ATCC 43504, 10(8) CFU/ml); Group II rats (n = 20) with experimental gastric ulcers received bacteria-free H. pylori filtrates; Group III rats with ulcers (n = 20) received saline alone; and Group IV control rats (n = 15) without ulcers received intact H. pylori organisms in suspension (ATCC 43504, 10(8) CFU/ml). At death, ulcer surface areas were measured with a dissecting microscope. Full-thickness sections were obtained for quantitative and qualitative histologic parameters, including the area of remaining mucosal necrosis; characteristics and cellular composition of restored mucosal architectures; and presence or absence of inflammation including counts of neutrophils and lymphocytes. H. pylori organisms were identified within the surface mucus and crypts using routine, special, and immunohistochemical stains. Our results indicate that the continued presence of either intact H. pylori organisms or bacteria-free H. pylori filtrates in the stomachs of rats with pre-existent gastric ulcers resulted in delayed healing of the ulcers and persistence of chronic active inflammation. Daily administration of suspensions of H. pylori organisms to sham-operated rats with intact gastric mucosa, however, resulted in no ulceration or inflammation despite identification of surface H. pylori organisms at death. The authors conclude that H. pylori alone causes little or no effect on an intact gastric mucosa in the rat, that either intact organisms or bacteria-free filtrates cause similar prolongation and delayed healing of pre-existing ulcers with active chronic inflammation, and that the presence of predisposing factors leading to disruption of gastric mucosal integrity may be required for the H. pylori enhancement of inflammation and tissue damage in the stomach.     

Isolating, immunophenotyping and ex vivo stimulation of CD4(+) and CD8(+) gastric lymphocytes during murine Helicobacter pylori infection

Helicobacter pylori infection is associated with severe chronic inflammation, yet the host immune response is rarely able to clear the bacterium. Thymus derived lymphocyte populations such as T helper 1, T helper 17, and T regulatory cells are known to play important roles in the chronicity of H. pylori infection as well as contributing to ongoing gastric pathology. It is yet to be established how these immune cell populations interact in the gastric environment during H. pylori infection. Mouse models of infection offer an opportunity to investigate these interactions in detail. Flow cytometric analysis provides excellent lymphocyte characterization due to its high specificity, sensitivity and potential to perform multiple simultaneous measurements. However, this requires a viable enriched single cell suspension after adequate tissue dissociation, which poses a challenge due to the heterogeneity of gastric tissue. We have evaluated several isolation techniques and have optimized a protocol to isolate and enrich lymphocytes from the H. pylori-infected murine stomach. EDTA/DTT followed by Collagenase IV digestion successfully dissociates an average of 1×10(7) cells per mouse. Further enrichment using Lympholyte M gradient yields on average 4×10(6) CD45(+) lymphocytes per stomach. Following isolation we compared lymphocyte stimulation by CD3/CD28, phorbol 12-myristate 13-acetate (PMA) and ionomycin or H. pylori lysate and determined that CD3/CD28 effectively induces stimulation of IFNγ and IL 17A, but impairs Foxp3 expression. Using an optimized protocol we observed a 2-fold increase of CD8(+) IFNγ-expressing lymphocytes localized specifically to the gastric compartment during H. pylori infection. The mechanisms of H. pylori immunopathogenesis are still considered enigmatic, therefore this optimized protocol can help delineate further novel immune cell targets that mediate H. pylori-induced pathology and identify the correlates of immunity for vaccine development.     

Evidence for ethnic tropism of Helicobacter pylori.

Helicobacter pylori infection in humans is linked to gastritis, gastric and duodenal ulcers, and gastric cancer. Peptic ulcer disease, as distinct from chronic asymptomatic infection, is strongly associated with expression of bacterial virulence markers, including a major antigen, CagA, and the vacuolating cytotoxin VacA. We have previously described significant differences in colonization rates, independent of socioeconomic status, among ethnic groups in New Zealand. To evaluate relative risks for peptic ulcer disease, we examined the frequency of two virulence markers in H. pylori strains infecting these ethnic groups. Although these markers occurred significantly more frequently in strains isolated from Polynesians than in strains from Europeans, this frequency was not reflected in the incidence of peptic ulcer disease in the two groups. DNA fingerprinting of the urease gene showed that Polynesians are more frequently infected by a group of strains which are genetically distinct from those affecting European New Zealanders. Our data suggest that separate bacterial lineages may have evolved in parallel with race-specific specialization.     

Cytotoxin production by Helicobacter pylori from patients with upper gastrointestinal tract diseases.

A cytotoxin produced by some Helicobacter pylori strains has recently been identified. The cytotoxin induces intracellular vacuolization of cultured cells. The aim of the present study was to examine the frequency of occurrence of cytotoxin-producing strains of H. pylori from subjects with upper gastrointestinal disease including nonulcer dyspepsia, gastric and duodenal ulcer disease, gastroesophageal reflux disease, and gastric cancer. Broth culture filtrates of clinical isolates of H. pylori recovered from 175 patients were used to inoculate Vero and HeLa cell monolayers for the detection of vacuolating cytotoxin activity. The results obtained demonstrated that the highest percentage of strains producing cytotoxin were found in subjects with peptic ulcer disease (gastric ulcer, 65%; duodenal ulcer, 66%; P < 0.01 compared with nonulcer dyspepsia, 38%). Of the 11 patients with gastroesophageal reflux disease, 4 of 5 patients in this group who had esophageal ulcers, were found to be infected with strains that produced cytotoxin. Three of the four patients with carcinoma of the stomach were also found to be infected with cytotoxic strains of H. pylori. With increasing severity of mucosal damage in subjects with a normal upper gastrointestinal tract, macroscopic gastritis, duodenitis, and peptic ulceration, there were corresponding increase in the proportion of strains producing cytotoxin; these increases were 32, 46, 50, and 66%, respectively. H. pylori strains from subjects with ulcer disease commonly produced vacuolating cytotoxin, suggesting that it may be a virulence factor in the pathogenesis of peptic ulcer disease.     

Helicobacter pylori induces transendothelial migration of activated memory T cells

Helicobacter pylori infection is associated with pronounced infiltration of granulocytes and lymphocytes into the gastric mucosa, resulting in active chronic gastritis that may develop into duodenal ulcer disease or gastric adenocarcinoma. Infiltrating T cells play a major role in the pathology of these diseases, but the signals involved in recruitment of T cells from blood to H. pylori-infected tissues are not well understood. We therefore examined H. pylori-induced T-cell transendothelial migration (TEM). The Transwell system, employing a monolayer of human umbilical vein endothelial cells, was used as a model to study TEM. H. pylori induced a significant T-cell migration, compared to spontaneous migration. CD4+ and CD8+ T cells migrated to the same extent in response to H. pylori, whereas there was significantly larger transmigration of memory T cells compared to naive T cells. Both H. pylori culture filtrate and urease induced migration, and the presence of the H. pylori cag pathogenicity island increased TEM. T-cell TEM was mediated by LFA-1-ICAM-1 interactions in accordance with an increased ICAM-1 expression on the endothelial cells after contact with H. pylori. Migrating T cells had increased expression of activation marker CD69 and chemokine receptors CXCR3, CCR4, and CCR9. Furthermore, T cells migrating in response to H. pylori secreted Th1 but not Th2 cytokines upon stimulation. In conclusion, our data indicate that live H. pylori and its secreted products contribute to T-cell recruitment to the gastric mucosa and that the responding T cells have an activated memory Th1 phenotype.     

Expression of cathepsins B, L, S, and D by gastric epithelial cells implicates them as antigen presenting cells in local immune responses

Helicobacter pylori infection is linked to chronic gastritis, peptic ulcer and gastric carcinoma. During H. pylori infection, class II MHC expression by the gastric epithelium increases, as does the number of local CD4(+) T cells, which appear to be important in the associated pathogenesis. These observations suggested that the epithelium might present antigens to T cells. Thus, we sought to determine whether gastric epithelial cells process antigens to establish their function as local antigen presenting cells (APC). We examined a panel of gastric epithelial cell lines for expression of the antigen processing cathepsins B (CB), L (CL), S (CS), and D (CD). The mRNA for these enzymes were detected by RT-PCR and the enzymes in the gastric epithelial cells were identified by various independent methods. We corroborated the expression of CB and CD on gastric epithelial cells from human biopsy samples. The functions of these proteases were confirmed by assessing their ability to digest ovalbumin, a conventional dietary antigen, and proteins from H. pylori. In summary, multiple lines of evidence suggest gastric epithelial cells process antigens for presentation to CD4(+) T cells. To our knowledge, these are the first studies to document the antigen processing capacity of human gastric epithelial cells.     

Helicobacter pylori and gastric cancer: factors that modulate disease risk

Helicobacter pylori is a gastric pathogen that colonizes approximately 50% of the world's population. Infection with H. pylori causes chronic inflammation and significantly increases the risk of developing duodenal and gastric ulcer disease and gastric cancer. Infection with H. pylori is the strongest known risk factor for gastric cancer, which is the second leading cause of cancer-related deaths worldwide. Once H. pylori colonizes the gastric environment, it persists for the lifetime of the host, suggesting that the host immune response is ineffective in clearing this bacterium. In this review, we discuss the host immune response and examine other host factors that increase the pathogenic potential of this bacterium, including host polymorphisms, alterations to the apical-junctional complex, and the effects of environmental factors. In addition to host effects and responses, H. pylori strains are genetically diverse. We discuss the main virulence determinants in H. pylori strains and the correlation between these and the diverse clinical outcomes following H. pylori infection. Since H. pylori inhibits the gastric epithelium of half of the world, it is crucial that we continue to gain understanding of host and microbial factors that increase the risk of developing more severe clinical outcomes.     

The intact dupA cluster is a more reliable Helicobacter pylori virulence marker than dupA alone

The duodenal ulcer promoting (dupA) gene, located in the plasticity region of Helicobacter pylori, is associated with duodenal ulcer development. dupA was predicted to form a type IV secretory system (T4SS) with vir genes around dupA (dupA cluster). We investigated the prevalence of dupA and dupA clusters and clarified associations between the dupA cluster status and clinical outcomes in the U.S. population. In all, 245 H. pylori strains were examined using PCR to evaluate the status of dupA and the adjacent vir genes predicted to form T4SS, in addition to the status of cag pathogenicity island (PAI). The associations between dupA cluster status and interleukin-8 (IL-8) and IL-12 production were also examined. The presence of dupA and all adjacent vir genes were defined as a complete dupA cluster. Many variations related to the status of dupA and dupA cluster genes were identified. Concurrent H. pylori infection and the presence of a complete dupA cluster increases duodenal ulcer risk compared to H. pylori infection with incomplete dupA cluster or without the dupA gene independent on the cag PAI status (adjusted odds ratio, 2.13; 95% confidence interval, 1.13 to 4.03). Gastric mucosal IL-8 levels were also significantly higher in the complete dupA cluster group than in other groups (P=0.01). In conclusion, although the causal relationship between the dupA cluster and duodenal ulcer development is not proved, the presence of a complete dupA cluster but not dupA alone, is associated with duodenal ulcer development.     

Localized accumulation of Russell body-containing plasma cells in gastric mucosa with Helicobacter pylori infection: 'Russell body gastritis'

One of the gastric biopsy specimens taken from a 53-year-old male showed localized accumulation of plasma cells containing Russell bodies, In association with infection of Helicobacter pylori (H. pylori ). An endoscoplc study demonstrated multiple ulcer scars in the antrum. Immunohistochemically, H. pylori Infection was Identified both on the surface of the foveolar epithelial cells and in the cytoplasm of macrophages in the lamina propria mucosae. Plasma cells filled with 'Russell bodies', so-called 'Motts cells', were immunoreactlve for CD45, CD79a and IgG. This seems to be a previously unrecognized tissue reaction in gastric mucosa associated with H. pylori Infection, which we have called 'Russell body gastritis'.