Immune and inflammatory responses to Helicobacter pylori infection

Helicobacter pylori antigens as immunomodulators of immune system

Helicobacter pylori (H. pylori) is one of the most prevalent human pathogens and the leading cause of chronic infection in almost half of the population in the world (~59%). The bacterium is a major leading cause of chronic gastritis, gastric and duodenal ulcers, and two type of malignancies, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Despite the immune responses mounted by the host, the bacteria are not cleared from the body resulting in a chronic infection accompanied by a chronic inflammation. Herein, a review of the literature discussing H. pylori antigens modulating the immune responses is presented. The mechanisms that are involved in the modulation of innate immune response, include modulation of recognition by pattern recognition receptors (PRRs) such as modulation of recognition by toll like receptors (TLR)4 and TLR5, modulation of phagocytic function, and modulation of phagocytic killing mediated by reactive oxygen species (ROS) and nitric oxide (NO). On the other hands, H. pylori modulates acquired immune response by the induction of tolerogenic dendritic cells (DCs), modulation of apoptosis, induction of regulatory T cells, modulation of T helper (Th)1 response, and modulation of Th17 response.

New insights into IL-6 family cytokines in metabolism, hepatology and gastroenterology

IL-6 family cytokines are defined by the common use of the signal-transducing receptor chain glycoprotein 130 (gp130). Increasing evidence indicates that these cytokines are essential in the regulation of metabolic homeostasis as well as in the pathophysiology of multiple gastrointestinal and liver disorders, thus making them attractive therapeutic targets. Over the past few years, therapies modulating gp130 signalling have grown exponentially in several clinical settings including obesity, cancer and inflammatory bowel disease. A newly engineered gp130 cytokine, IC7Fc, has shown promising preclinical results for the treatment of type 2 diabetes, obesity and liver steatosis. Moreover, drugs that modulate gp130 signalling have shown promise in refractory inflammatory bowel disease in clinical trials. A deeper understanding of the main roles of the IL-6 family of cytokines during homeostatic and pathological conditions, their signalling pathways, sources of production and target cells will be crucial to the development of improved treatments. Here, we review the current state of the role of these cytokines in hepatology and gastroenterology and discuss the progress achieved in translating therapeutics targeting gp130 signalling into clinical practice.

Microbes and Viruses Are Bugging the Gut in Celiac Disease. Are They Friends or Foes?

The links between microorganisms/viruses and autoimmunity are complex and multidirectional. A huge number of studies demonstrated the triggering impact of microbes and viruses as the major environmental factors on the autoimmune and inflammatory diseases. However, growing evidences suggest that infectious agents can also play a protective role or even abrogate these processes. This protective crosstalk between microbes/viruses and us might represent a mutual beneficial equilibrium relationship between two cohabiting ecosystems. The protective pathways might involve post-translational modification of proteins, decreased intestinal permeability, Th1 to Th2 immune shift, induction of apoptosis, auto-aggressive cells relocation from the target organ, immunosuppressive extracellular vesicles and down regulation of auto-reactive cells by the microbial derived proteins. Our analysis demonstrates that the interaction of the microorganisms/viruses and celiac disease (CD) is always a set of multidirectional processes. A deeper inquiry into the CD interplay with Herpes viruses and Helicobacter pylori demonstrates that the role of these infections, suggested to be potential CD protectors, is not as controversial as for the other infectious agents. The outcome of these interactions might be due to a balance between these multidirectional processes.

Role of LPS-elicited signaling in triggering gastric mucosal inflammatory responses to H. pylori: modulatory effect of ghrelin

Infection with Helicobacter pylori is a primary culprit in the etiology of gastric disease, and its cell-wall lipopolysaccharide (LPS) is recognized as a potent endotoxin responsible for triggering a pattern of the mucosal inflammatory responses. The engagement by the LPS of gastric mucosal Toll-like receptor 4 (TLR4) leads to initiation of signal transduction events characterized by the activation of mitogen-activated protein kinase (MAPK) cascade, induction of phosphoinositide-specific phospholipase C (PLC)/protein kinase C (PKC)/phosphatidylinositol 3-kinase (PI3K) pathway, and up-regulation in Src/Akt. These signaling events in turn exert their influence over H. pylori-elicited excessive generation of NO and PGE2 caused by the disturbances in nitric oxide synthase and cyclooxygenase isozyme systems, increase in epidermal growth factor receptor transactivation, and the induction in matrix metalloproteinase-9 (MMP-9) release. Interestingly, the extent of gastric mucosal inflammatory response to H. pylori is influenced by a peptide hormone, ghrelin, the action of which relays on the growth hormone secretagogue receptor type 1a (GHS-R1a)-mediated mobilization of G-protein dependent transduction pathways. Yet, the signals triggered by TLR-4 activation as well as those arising through GHS-R1a stimulation converge at MAPK and PLC/PKC/PI3K pathways that form a key integration node for proinflammatory signals generated by H. pylori LPS as well as for those involved in modulation of inflammation by ghrelin. Hence, therapeutic targeting these signals' convergence and integration node could provide a novel and attractive opportunities for developing more effective treatments of H. pylori-related gastric disease.

Heme binding and peroxidase activity of a secreted minicatalase

Microbial pathogens often require efficient and robust H₂ O₂ scavenger activities to survive in the presence of reactive oxygen species generated by inflammatory responses. In addition to catalases and peroxidases, enzymes known to scavenge H₂ O₂ , a novel class of secreted minicatalases is found in diderm bacteria. Here, we characterize the Helicobacter pylori (Hp) minicatalase: a monomeric hemoprotein with catalase core homology. Overexpression of Hp minicatalase rescued a catalase/peroxidase-deficient Escherichia coli phenotype under aerobic conditions and limited H₂ O₂ stress. The purified enzyme lacks catalase activity, but has strong (k_cat > 100 s^-1 ) H₂ O₂ -dependent peroxidase activity toward a variety of organic substrates. Our investigations into heme binding revealed that the heme cofactor is assembled in the periplasm to form the functional holoprotein. Furthermore, we observed the presence of a disulfide bond near the heme cavity of Hp minicatalase, which is conserved in secreted minicatalases and, therefore, may play a role in heme binding.

Characterization of Lactobacillus salivarius strains B37 and B60 capable of inhibiting IL-8 production in Helicobacter pylori-stimulated gastric epithelial cells

Background

Interleukin (IL)-8 is the key agent for initiating an inflammatory response to infection with Helicobacter pylori. Some strains of Lactobacillus spp. are known to colonize the stomach and suppress inflammation caused by H. pylori. In this study, we characterized two gastric-derived lactobacilli, Lactobacillus salivarius (LS) strains B37 and B60, capable of inhibiting H. pylori-induced IL-8 production by gastric epithelial cells.

Results

Conditioned media from LS-B37 and LS-B60 suppressed H. pylori-induced IL-8 production and mRNA expression from AGS cells without inhibiting H. pylori growth. These conditioned media suppressed the activation of NF-κB but did not suppress c-Jun activation. IL-8 inhibitory substances in conditioned media of LS-B37 and LS-B60 are heat-stable and larger than 100 kDa in size. The inhibitory activity of LS-B37 was abolished when the conditioned medium was treated with α-amylase but still remained when treated with either proteinase K, trypsin, lipase or lysozyme. The activity of LS-B60 was abolished when the conditioned medium was treated with either amylase or proteinase K but still remained when treated with lysozyme. Treatment with lipase and trypsin also significantly affected the inhibitory activity of LS-B60 although the conditioned medium retained IL-8 suppression statistically different from media control.

Conclusions

These results suggest that L. salivarius strains B37 and B60 produce different immunomodulatory factors capable of suppressing H. pylori-induced IL-8 production from gastric epithelial cells. Our results suggest that the large, heat-stable immunomodulatory substance(s) present in the LCM of LS-B37 is a polysaccharide, while the one(s) of LS-B60 is either complex consisting of components of polysaccharide, lipid and protein or includes multiple components such as glycoprotein and lipoprotein.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0861-x) contains supplementary material, which is available to authorized users.

Review: Molecular mimicry of host structures by lipopolysaccharides of Campylobacter and Helicobacter spp.: implications in pathogenesis

Molecular mimicry of host structures by the saccharide portion of lipopolysaccharide (LPS) contributes to the virulence of certain strains of mucosal pathogens. Mimicry by the low molecular weight (low-Mr) LPSs of Neisseria and Haemophilus spp. have been the most extensively studied. However, studies within the last decade have revealed other types of mimicry within the saccharide moieties of LPSs of the enteric pathogen Campylobacter jejuni and the gastroduodenal pathogen Helicobacter pylori. The core oligosaccharides of low-Mr LPSs of C. jejuni serotypes which are associated with the development of Guillain-Barré syndrome (GBS), a neurological disorder, exhibit mimicry of gangliosides. Cross-reactive antibodies between LPSs and gangliosides which are induced during antecedent C. jejuni infection are considered to play an important role in GBS pathogenesis. The O-polysaccharide chains of high-Mr LPSs of a number of H. pylori strains mimic Lewisx and/or Lewisy blood group antigens. This mimicry may camouflage the bacterium in the gastric mucosa upon initial infection. With the progression of infection, the mimicry may play a role in immune response regulation and the induction of autoantibodies against the gastric proton pump, a glycoprotein that also expresses Lewis antigens.

Role of surfactant protein D (SP-D) in innate immunity in the gastric mucosa: evidence of interaction with Helicobacter pylori lipopolysaccharide

Surfactant protein D (SP-D) is a collagenous glycoprotein, a collectin, which functions as a pathogen-associated molecular pattern (PAMP) recognition receptor in the innate immune response. Although originally identified in the lung as a component of surfactant, SP-D also occurs in the gastric mucosa at the luminal surface and within gastric pits of mucus-secreting cells. Infection with the gastroduodenal pathogen Helicobacter pylori up-regulates expression of SP-D in human patients with gastritis, and its influence on colonization has been demonstrated in a Helicobacter SP-D-deficient (SP-D—/ —) mouse model. SP-D binds and agglutinates H. pylori cells in a lectin-specific manner, and has been shown to bind H. pylori lipopolysaccharide. Furthermore, evidence indicates that H. pylori varies LPS O-chain structure to evade SP-D binding which is speculated aids persistence of this chronic infection.

A Newly Developed Nested PCR Assay for the Detection of Helicobacter pylori in the Oral Cavity

GOALS

To develop a new nested polymerase chain reaction (PCR) assay for identifying Helicobacter pylori DNA from dental plaque.

BACKGROUND

H. pylori is one of the most common chronic bacterial pathogens in humans. The accurate detection of this organism is essential for proper patient management and for the eradication of the bacteria following treatment.

STUDY

Forty-nine patients (24 males and 25 females; mean age: 51; range, 19 to 94 y) were investigated for the presence of H. pylori in dental plaque by single-step PCR and nested PCR and in the stomach by single-step PCR, nested PCR, and histologic examination.

RESULTS

The newly developed nested PCR assay identified H. pylori DNA in gastric biopsies of 18 patients who were histologically classified as H. pylori-positive and 2 additional biopsies of patients who were H. pylori-negative by histologic examination (20/49; 40.8%). Dental plaque samples collected before and after endoscopy from the 49 patients revealed that single-step PCR did not detect H. pylori but nested PCR was able to detect H. pylori DNA in 40.8% (20/49) patients. Nested PCR gave a higher detection rate (40.8%, 20/49) than that of histology (36.7%, 18/49) and single-step PCR. When nested PCR results were compared with histology results there was no significant difference between the 2 methods.

CONCLUSIONS

Our newly developed nested PCR assay is at least as sensitive as histology and may be useful for H. pylori detection in patients unfit for endoscopic examination.

Helicobacter pylori Infection in Early Childhood and Growth at School Age

BACKGROUND

There are conflicting results regarding the role of H. pylori in children's growth. We examined differences in growth indices at school age according to H. pylori infection acquisition in preschool age.

MATERIALS AND METHODS

A prospective study was undertaken between 2004 and 2009, in which of healthy children (N = 139, ages 3-5 years at baseline) were tested for the presence of H. pylori antigen in their stool using enzyme-linked immunoassay and followed-up till age 6-9 years (median follow-up time 45 months). Height, weight, and hemoglobin levels were measured, and socioeconomic data were obtained. Z scores of height for age, weight for age, and body mass index for age at baseline and follow-up were calculated using the 2000 Center for Disease Control and Prevention growth reference curves. Growth velocity (cm/month) between preschool and school age was compared between H. pylori-infected and uninfected children using mixed models.

RESULTS

Fifty-three percent of the children were H. pylori positive at baseline, and all except one child tested positive at follow-up. The adjusted mean Z score of height for age at follow-up was significantly lower among H. pylori-infected children than uninfected ones: 0.15 (95% confidence intervals (CIs) 0.02, 0.29) and 0.45 (95% CI 0.29, 0.60), respectively (p = .002). Growth velocity was slower in the former group -0.0264 cm/month (95% CI -0.047, -0.005) (p = .014), after adjusting for baseline height and age. H. pylori infection was not associated with body weight.

CONCLUSIONS

Helicobacter pylori infection acquired in early childhood may have long-term adverse influence on linear growth at school age.

Is Helicobacter pylori infection a risk factor for childhood periodic syndromes?

Background and objectives

Helicobacter pylori (H. pylori) infection has been assumed to have roles in various extra-digestive diseases. The current study was designed to evaluate the incidence of H. pylori infection in patients with cyclic vomiting syndrome and its possible role in the etiology of this disease.

Design and setting

In this case-control study, 120 cases with diagnoses of cyclic vomiting or abdominal migraine who were registered at the Gastroenterology Clinic at Shiraz University of Medical Sciences from 2010 to 2013 were enrolled.

Materials and methods

Primarily information regarding the patients' diseases were collected with a data gathering sheet, and fresh morning stool samples were collected from the patients and examined for H. pylori stool antigen with the H. pylori Ag EIA test kit. The results were compared with those of healthy children from the control group.

Results

A total of 120 patients with cyclic vomiting (47.5%) and abdominal migraine (52.5%) with a mean age of 7.1 ± 3.4 (range 2-16 years) and a male-to-female ratio of 1.6 were included. The HPs Ag tests were positive in only 7 (5.8%) patients in our case group, and the HPs Ag tests were positive in 13 (13%) of the children in the control group; this difference was statistically insignificant.

Conclusion

Our study did not support H. pylori infection as an etiological factor in CV or AM.

Prevalence of H. Pylori in Tonsillar Tissue of Patients with Chronic Recurrent Tonsillitis Using Rapid Urease Test in a Tertiary Referral Hospital in Sub Saharan Africa

There has been conflicting results regarding the presence of H. pylori in tonsillar tissue. Our objective was to analyze for the presence of H. pylori in tonsillar tissue in patients undergoing tonsillectomy for chronic recurrent tonsillitis using rapid urease test in a Tertiary care academic medical center in a sub Saharan hospital. A prospective cross-sectional analysis of 39 consecutive cases of patients undergoing tonsillectomy secondary to chronic recurrent tonsilitis was done. Rapid urease test was conducted on each tonsillectomy tissue and results were determined using color change at specific time intervals within 24 h. Average age of the patients was 4.3 years. Among the 39 tonsillar tissues analysed using rapid urease test, H. pylori was present in 30.5 % of the samples. Colonisation by H. pylori of the palatine tonsils is a new frontier with conflicting results depending on the accuracy of the test method used and population studied. More studies need to be performed to ascertain the different rates of colonisation based on geographical regions.

Helicobacter pylori antigen HP0986 (TieA) interacts with cultured gastric epithelial cells and induces IL8 secretion via NF-κB mediated pathway

BACKGROUND

The envisaged roles and partly understood functional properties of Helicobacter pylori protein HP0986 are significant in the context of proinflammatory and or proapoptotic activities, the two important facilitators of pathogen survival and persistence. In addition, sequence analysis of this gene predicts a restriction endonuclease function which remained unknown thus far. To evaluate the role of HP0986 in gastric inflammation, we studied its expression profile using a large number of clinical isolates but a limited number of biopsies and patient sera. Also, we studied antigenic role of HP0986 in altering cytokine responses of human gastric epithelial (AGS) cells including its interaction with and localization within the AGS cells.

MATERIALS AND METHODS

For in vitro expression study of HP0986, 110 H. pylori clinical isolates were cultured from patients with functional dyspepsia. For expression analysis by qRT PCR of HP0986, 10 gastric biopsy specimens were studied. HP0986 was also used to detect antibodies in patient sera. AGS cells were incubated with recombinant HP0986 to determine cytokine response and NF-κB activation. Transient transfection with HP0986 cloned in pEGFPN1 was used to study its subcellular localization or homing in AGS cells.

RESULTS

Out of 110 cultured H. pylori strains, 34 (31%) were positive for HP0986 and this observation was correlated with in vitro expression profiles. HP0986 mRNA was detected in 7 of the 10 biopsy specimens. Further, HP0986 induced IL-8 secretion in gastric epithelial cells in a dose and time-dependent manner via NF-κB pathway. Serum antibodies against HP0986 were positively associated with H. pylori positive patients. Transient transfection of AGS cells revealed both cytoplasmic and nuclear localization of HP0986.

CONCLUSION

HP0986 was moderately prevalent in clinical isolates and its expression profile in cultures and gastric biopsies points to its being naturally expressed. Collective observations including the induction of IL-8 via TNFR1 and NF-κB, subcellular localization, and seropositivity data point to a significant role of HP0986 in gastroduodenal inflammation. We propose to name the HP0986 gene/protein as 'TNFR1 interacting endonuclease A (TieA or tieA)'.

Role of Tumor Necrosis Factor-Alpha and Interferon-Gamma inHelicobacter pyloriInfection

Immune responses to Helicobacter pylori infection play important roles in gastroduodenal diseases. The contributions of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) to the induction of gastric inflammation and to the protection from H. pylori infection were investigated using TNF-alpha geneknockout (TNF-alpha(-/-)) mice and IFN-gamma gene-knockout (IFN-gamma(-/-)) mice. We first examined the colonizing ability of H. pylori strain CPY2052 in the stomach of C57BL/6 wild-type and knockout mice. The number of H. pylori colonized in the stomach of IFN-gamma(-/-) and TNF-alpha(-/-) mice was higher than that of wild-type mice. These findings suggest that TNF-alpha and IFN-gamma may play a protective role in H. pylori infection. Furthermore, we examined the contribution of TNF-alpha and IFN-gamma to gastric inflammation. The CPY2052-infected TNF-alpha(-/-) mice showed a moderate infiltration of mononuclear cells in the lamina propria and erosions in the gastric epithelium as did wild-type mice, whereas the CPY2052-infected IFN-gamma(-/-) mice showed no inflammatory findings even 6 months after infection. These results demonstrate that IFN-gamma may play an important role in gastric inflammation induced by H. pylori infection, whereas TNF-alpha may not participate in the development of inflammatory response.

Hypermethylation of TGF-β1 gene promoter in gastric cancer

AIM: To examine transforming growth factor-β1 (TGF-β1) promoter methylation in gastric cancer and to determine if Helicobacter pylori (H. pylori) or interleukin (IL)-1β could induce TGF-β1 hypermethylation in vitro.

METHODS: We examined the frequency and extent of TGF-β1 promoter methylation using methylation-specific PCR in the gastric tissues from 47 gastric cancer patients and 39 non-gastric cancer subjects. H. pylori infection was confirmed by a positive result from either a serological test, histological analysis or C¹³ urea breath test. GES-1 and MKN-45 cells co-cultured with H. pylori or treated with IL-1β for 12, 24 and 48 h in vitro tested the effects of H. pylori or IL-1β on TGF-β1.

RESULTS: Twenty-four/forty-seven (51%) cases of gastric cancer (GC) tissues showed TGF-β1 promoter methylation, 15/47 (31.9%) cases of matched non-cancerous gastric mucosa tissues from the GC patients, and 11/39 (28%) case of the normal gastric mucosa tissues from non-GC subjects showed TGF-β1 promoter methylation (51% vs 28%, P < 0.05). Significantly higher levels of methylation of TGF-β1 were found in the tumor tissues than in non-tumor tissues from GC patients (0.24 ± 0.06 vs 0.17 ± 0.04, P < 0.05) and normal gastric tissues from non-GC subjects (0.24 ± 0.06 vs 0.15 ± 0.03, P < 0.05). TGF-β1 methylation was found in 48.3% of H. pylori-positive gastric mucosal tissues whereas only 23.1% of H. pylori-negative gastric mucosal tissues showed TGF-β1 methylation (48.3% vs 23.1%, P < 0.05). IL-1β appeared to induce a dose-dependent methylation of TGF-β1 and the strongest methylation was observed in GES-1 cells treated with 2.5 ng/mL of IL-1β for 48 h. Further studies showed that pre-treatment of GES-1 cells with 20 ng/mL IL-1RA for 1 h could partially abolish the effect of IL-1β on TGF-β1 methylation. Infection of GES-1 cells by H. pylori was not found to induce significant TGF-β1 promoter methylation.

CONCLUSION: Our data revealed that TGF-β1 promoter is methylated in GC patients. IL-1β may be an important mediator for H. pylori induced gene methylation during GC development.

Association of Helicobacter pylori infection with inflammatory cytokine expression in patients with gallbladder cancer

AIM

Gallbladder cancer (GBC) may be associated with Helicobacter pylori. The present study was designed to analyze the association of cytokine expression with H. pylori in patients with GBC.

METHODS

GBC tissue sample and 5 mL blood were collected from each of 54 GBC patients. H. pylori was identified in tissue samples using biochemical tests, histology, culture, nested polymerase chain reaction (PCR), and partial genome sequencing. Tissue samples were categorized as H. pylori-positive (case) and H. pylori-negative groups (control) on the basis of nested PCR of tissue sample. Cytokines interleukin 1-β (IL-1β), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-5 (IL-5) were assayed in blood samples using ELISA.

RESULTS

Presence of H. pylori was confirmed in 18 (33 %) of 54 GBC tissue samples. Levels of IL-1β (p = 0.001) and TNF-α (p = 0.01) were significantly elevated in H. pylori-positive GBC compared to the control group. IFN-γ and IL-5 levels did not significantly differ between the two groups.

CONCLUSIONS

H. pylori DNA was detected in the gallbladder of a third of GBC patients and was associated with higher circulating levels of some cytokines.

Prevalence of virulent Helicobacter pylori strains in patients affected by idiopathic dysrhythmias

Helicobacter pylori virulent strains have been shown to affect cardiovascular diseases through molecular mimicry mechanisms. Silent autoimmune myocarditis has been hypothesized to be the cause of idiopathic dysrhythmias (IA). The aim of this study is to assess the prevalence of virulent H. pylori strains in patients affected by IA. In this study,54 patients (40 men, mean age 44 ± 17 years) affected by IA and 50 healthy subjects (34 men, mean age 45 ± 9) were evaluated. IA, defined as dysrhythmias with no evidence of other cardiac pathology, were either supraventricular (SVA, 23 patients; mean age 45 ± 15 years) or ventricular (VA, 31 patients; mean age 42 ± 18 years). H. pylori infection and gastrointestinal (GI) symptoms were evaluated. H. pylori strains expressing the cytotoxin-associated gene A (cagA) and the vacuolating-cytotoxin A (vacA) were also assessed through western blot. The prevalence of H. pylori is similar in IA patients and in controls (42 vs. 44%; p > 0.05); H. pylori infection is observed in 48 and 39% of the patients are affected by SVA and VA, respectively. The prevalence of CagA-positive strains is increased in IA patients compared to controls (65 vs. 42%; p < 0.01); similarly, the prevalence of VacA-positive strains is also increased in IA patients (74 vs. 46%; p < 0.006). Excluding belching, infected patients did not show any difference in GI symptoms, when compared to non-infected subjects. From this study it is concluded that there is an epidemiological link between CagA and VacA-positive H. pylori strains in IA patients.

Inhibitory effects of eupatilin on tumor invasion of human gastric cancer MKN-1 cells

Extracts of the whole herb of Artemisia asiatica Nakai (Asteraceae) are used in traditional oriental medicine to treat inflammation. Eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone) is one of the pharmacologically active components found in A. asiatica, and has been shown to possess anti-tumoral effects in some malignancies, including gastric cancer. However, its anti-metastatic effect in gastric cancer is hardly known. In this study, anti-metastatic effect of eupatilin was investigated in the human gastric cancer cell line, MKN-1. Eupatilin inhibited MKN-1 growth in a dose- and a time-dependent manner, and induced apoptosis with a concomitant increase of caspase-3 activity. ELISA demonstrated that release of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, and IL-8) was significantly reduced by eupatilin. And p-AKT and p-ERK (p44/42) was reduced. Expression level of β-catenin and integrin was reduced and p-GSKβ was increased. In transcription reporter system, the activity of the transcriptional factor, NF-κB, was reduced by eupatilin and the expression of p65 was down-regulated when MKN-1 cells were treated with eupatilin. Moreover, a zymography study revealed that this reduction in invasive potential resulted from a reduction in type IV collagenolytic (gelatinolytic) activity. The expressions of metalloproteinases (MMP-2 and MMP-9) were also reduced in MKN-1 cells treated with eupatilin. In vitro invasion assay, eupatilin inhibited MKN-1 penetrating reconstituted basement membrane barriers. These results suggest that eupatilin inhibits the MKN-1 gastric cancer cell proliferation via activation of caspase-3 and the metastatic potential of gastric cancer cells via down-regulation of NF-κB activity followed by reduction of pro-inflammatory cytokine-mediated MMPs expressions.

A role for altered phagosome maturation in the long-term persistence of Helicobacter pylori infection

The vigorous host immune response that is mounted against Helicobacter pylori is unable to eliminate this pathogenic bacterium from its niche in the human gastric mucosa. This results in chronic inflammation, which can develop into gastric or duodenal ulcers in 10% of infected individuals and gastric cancer in 1% of infections. The determinants for these more severe pathologies include host (e.g., high IL-1β expression polymorphisms), bacterial [e.g., cytotoxicity-associated gene (cag) pathogenicity island], and environmental (e.g., dietary nitrites) factors. However, it is the failure of host immune effector cells to eliminate H. pylori that underlies its persistence and the subsequent H. pylori-associated disease. Here we discuss the mechanisms used by H. pylori to survive the host immune response and, in particular, the role played by altered phagosome maturation.

Clinical characteristics and the expression profiles of inflammatory cytokines/cytokine regulatory factors in asymptomatic patients with nodular gastritis

BACKGROUND

Nodular gastritis (NG) has been reported in adult dyspeptic patients, whereas information on NG in asymptomatic patients is limited.

AIMS

To evaluate the prevalence, clinico-epidemiological characteristics, and expression profiles of inflammatory cytokines or cytokine regulatory factors of NG in asymptomatic adults.

METHODS

A cross-sectional study was conducted prospectively using 2,579 consecutive asymptomatic subjects who underwent screening esophagogastroduodenoscopy. The expression of inflammatory cytokines or cytokine regulatory factors in the gastric mucosa of NG patients was evaluated using immunofluorescence staining.

RESULTS

NG was diagnosed in 52 patients (2.0%) and showed a predilection for females (M:F = 1:1.89) and young adults (median age: 34 years; range: 25-51 years). All NG patients were positive for Helicobacter pylori infection. Based on multivariate analysis, the risk of NG was increased in patients younger than 40 years (OR, 7.57; 95% CI, 3.76-15.24) and of the female gender (OR, 2.12; 95% CI; 1.05-4.28). Immunofluorescent staining for interleukin (IL)-1β, IL-10, IL-18, IL-18 binding protein, IL-32, IL-33, and neutrophil proteinase 3 (PR3) was performed on cryosections of gastric mucosa. Interestingly, the expression of PR3 was highly increased in the gastric biopsies from asymptomatic NG patients but was expressed infrequently in the controls.

CONCLUSIONS

Asymptomatic NG is associated with H. pylori infection, and a predilection for this condition exists in young females. The PR3 expression of gastric mucosa might play an important role in the pathogenesis of NG.

Inhibition of H. pylori colonization and prevention of gastritis in murine model

Helicobacter pylori is a Gram-negative spiral bacterium that colonizes human gastric mucosa causing infection. In this study aiming at inhibition of H. pylori infection we made an attempt to evaluate immunogenicity of the total (UreC) and C-terminal (UreCc) fragments of H. pylori urease. Total UreC and its C-terminal fragment were expressed in E. coli. Recombinant proteins were analyzed by SDS-PAGE and western blot and then purified by Ni-NTA affinity chromatography. Female C57BL6/j mice were immunized with the purified proteins (UreC and UreCc). Antibody titers from isolated sera were measured by ELISA. Immunized mice were then challenged by oral gavage with live H. pylori Sydney strain SS1. Total of 109 CFU were inoculated into stomach of immunized and unimmunized healthy mice three times each at one day interval. Eight weeks after the last inoculation, the blood sample was collected and the serum antibody titer was estimated by ELISA. Stomach tissues from control and experimental animal groups were studied histopathologically. UreC and UreCc yielded recombinant proteins of 61 and 31 kDa respectively. ELIZA confirmed establishment of immunity and the antibodies produced thereby efficiently recognized H. pylori and inhibited its colonization in vivo. Pathological analysis did not reveal established infection in immunized mice challenged with H. pylori. The results support the idea that UreC and UreCc specific antibodies contribute to protection against H. pylori infections.

Helicobacter pylori cholesteryl glucosides interfere with host membrane phase and affect type IV secretion system function during infection in AGS cells

Helicobacter pylori infection is an aetiological cause of gastric disorders worldwide. H. pylori has been shown to assimilate and convert host cholesterol into cholesteryl glucosides (CGs) by cholesterol-α-glucosyltransferase encoded by capJ. Here, we show that CapJ-deficient (ΔcapJ) H. pylori resulted in greatly reduced type IV secretion system (TFSS)-associated activities, including the hummingbird phenotype of AGS cells, IL-8 production, CagA translocation/phosphorylation and CagA-mediated signalling events. Complementation of the ΔcapJ mutation with wild type cagJ or by adding CGs-containing lysates or exogenous fluorophore-tagged CGs reversed the mutant phenotypes. We also show that the wild-type but not ΔcapJ H. pylori recruited raft-associated components to sites of bacterial attachment. Fluorescence recovery after photobleaching (FRAP) analysis of AGS cells treated with fluorescence-tagged cholesterol/CGs revealed that there was a higher proportion of CGs associated with immobile fractions. CGs-associated membranes were also more resistant to a cold detergent extraction. Thus, we propose that CGs synthesized by H. pylori around host-pathogen contact sites partition in detergent-resistant membranes (DRMs), alters lateral-phase segregation in membrane and reorganizes membrane architecture. These processes together promote the formation of a functional TFSS and H. pylori infection.

Effect of Helicobacter pylori infection on symptoms of gastroenteritis due to enteropathogenic Escherichia coli in adults

BACKGROUND

Helicobacter pylori can cause hypochlorhydria in some hosts and predispose to diarrheal infections.

AIMS

We tested the hypothesis that chronic H. pylori infection increases the risk of diarrheal illness due to an acid-sensitive organism: enteropathogenic Escherichia coli (EPEC).

METHODS

After testing healthy adult volunteers for H. pylori, 19 infected and 26 uninfected subjects had gastric pH probes placed and were given 5-10 × 10(9) EPEC organisms; six had previously received a proton pump inhibitor. We measured diarrhea and created a composite gastroenteritis severity score based on symptoms in the 48 h following exposure. Outcomes were compared using logistic regression and analysis of covariance.

RESULTS

More H. pylori-infected (36.8%) than H. pylori-uninfected subjects (7.7%) were hypochlorhydric (P = 0.02). Six (31.6%) H. pylori-infected and five H. pylori-uninfected subjects (19.2%) developed diarrhea (P = 0.34). Hypochlorhydria was a strong risk factor for diarrhea [odds ratio (OR) 6.25, confidence interval (CI): 1.29-30.35]. After adjusting for hypochlorhydria and EPEC dose, H. pylori was not associated with diarrhea (OR 0.89, CI: 0.17-4.58). Among those with symptoms, H. pylori-infected subjects had lower gastroenteritis severity score than did H. pylori-uninfected subjects (2.6, CI: 1.9-3.4 versus 1.5, CI: 1.1-1.9, P = 0.01), particularly if they were also hypochlorhydric (3.8, CI: 2.3-5.3 versus 1.9, CI: 1.3-2.5, P = 0.02).

CONCLUSIONS

In adults, H. pylori infection was associated with hypochlorhydria but had no detectable effect on occurrence of diarrhea. Among symptomatic subjects, H. pylori infection decreased severity of gastroenteritis.

Hemorrhage-induced intestinal damage is complement-independent in Helicobacter hepaticus-infected mice

With more than half of the world population infected, Helicobacter infection is an important public health issue associated with gastrointestinal cancers and inflammatory bowel disease. Animal studies indicate that complement and oxidative stress play a role in Helicobacter infections. Hemorrhage (HS) induces tissue damage that is attenuated by blockade of either complement activation or oxidative stress products. Therefore, we hypothesized that chronic Helicobacter hepaticus infection would modulate HS-induced intestinal damage and inflammation. To test this hypothesis, we examined HS-induced jejunal damage and inflammation in uninfected and H. hepaticus-infected mice. Helicobacter hepaticus infection increased HS-induced midjejunal mucosal damage despite attenuating complement activation. In addition, infection alone increased chemokine secretion, changing the HS-induced neutrophil infiltration to a macrophage-mediated inflammatory response. The HS-induced macrophage infiltration correlated with increased secretion of tumor necrosis factor-α and nitric oxide in the infected mice. Together, these data indicate that Helicobacter infection modulates the mechanism of HS-induced intestinal damage and inflammation from a complement-mediated response to a macrophage response with elevated tumor necrosis factor-α and nitric oxide. These data indicate that chronic low-level infections change the response to trauma and should be considered when designing and administering therapeutics.

Ectodomain shedding of E-cadherin and c-Met is induced by Helicobacter pylori infection

Helicobacter pylori, a microaerophilic gram-negative bacterium, colonizes the human stomach. About 50% of the world's population is infected, and this infection is considered as the major risk factor for the development of gastric adenocarcinomas in 1% of infected subjects. Carcinogenesis is characterized by the process of epithelial-to-mesenchymal transition (EMT), in the course of which fully differentiated epithelial cells turn into depolarized and migratory cells. Concomitant disruption of adherence junctions (AJ) is facilitated by growth factors like hepatocyte growth factor 1 (HGF-1), but has been also shown to depend on ectodomain shedding of E-cadherin. The aim of this study was to investigate the impact of infection with H. pylori of NCI-N87 gastric epithelial cells on the shedding of E-cadherin and HGF-receptor c-Met. Our results show that infection with H. pylori provokes shedding of the surface proteins c-Met and E-cadherin. Evidence is provided that ADAM10 contributes to the shedding of c-Met and E-cadherin.

Interleukin-13 mucosal production in Helicobacter pylori-related gastric diseases

A shift from Th1 (IFN-gamma) towards Th2 (IL-4)-type immune response was found in patients with gastric cancer and dysplasia. Recently, IL-13 has been described as a central mediator of Th2-dominant immune response in different inflammatory diseases.

AIM AND METHODS

to analyse, by Enzyme-Linked-Immuno-SPOT (ELISPOT) assay and immunohistochemistry, the IL-13 production of mononuclear cells obtained from gastric biopsies of 19 H. pylori-negative subjects and 23 H. pylori-positive patients.

RESULTS

By ELISPOT, we did not find any significant variation of the spot range number of IL-13, IL-4 and IFN-gamma secreting cells, irrespective of H. pylori status. After antigenic exposition, the spot range for IL-13, IL-4 and IFN-gamma significantly increased (p<.0001) only in H. pylori-positive patients. A prevalent Th1 (IFN-gamma) immunoresponse was observed in 2/23 cases with active gastritis, while a prevalent Th2 (IL-13 and IL-4) was detected in 5/23 cases all with atrophic chronic gastritis of whom two with intestinal metaplasia. By immunohistochemistry, IL-13, IL-4 and IFN-gamma were detectable in all cases directly related to the inflammatory infiltrate. In the two cases with intestinal metaplasia, IL-13 and IL-4 were localised in both inflammatory and epithelial cells. This immunopattern was confirmed in selected additional 10 cases of H. pylori-positive chronic atrophic gastritis with intestinal metaplasia and 10 cases of intestinal type gastric cancer.

CONCLUSION

These preliminary results suggest that IL-13 could be implicated in the different outcome of H. pylori infection.

Gastrointestinal tract pathology in patients with common variable immunodeficiency (CVID): a clinicopathologic study and review

BACKGROUND

Common variable immunodeficiency (CVID) is characterized by a host of gastrointestinal (GI) lesions that can mimic other conditions.

METHODS

We reviewed clinical documentation and samples from 132 separate GI biopsy or resection sites on 20 CVID patients obtained over a 26-year period, including biopsies from the colon (34), esophagus (19), small intestine (38), and stomach (35), a partial gastrectomy, small bowel resection, colectomy, 2 cholecystectomies, and 1 appendectomy.

RESULTS

There were 13 males and 7 females. Nine patients were children (10 y and younger) and 11 were adults. Age at diagnosis ranged from 6 months to 62 years (median, 35.5 y), and age at biopsy ranged from 10 months to 67 years (median, 38 y). Esophageal samples often showed intraepithelial neutrophils, accompanied by candida. Half of patients' esophageal biopsies had prominent intraepithelial lymphocytosis, one of which also had prominent apoptosis. The stomachs of 67% of patients lacked plasma cells. Most showed lymphoid aggregates. An increase in apoptosis was detected in biopsies from a third. About 20% had a lymphocytic gastritis pattern. Intraepithelial neutrophils were found in a subset, accompanied by various infections [cytomegalovirus (CMV), Helicobacter pylori, and Cryptosporidium]. Granulomas were found in 1 patient. Gastric adenocarcinoma was identified in one patient. There was a paucity of small bowel plasma cells in the majority of patients (68%). The small bowel showed prominent lymphoid aggregates in about half (47%). An increase in apoptosis was detected in specimens from about 20%. Increased intraepithelial lymphocytes (IELs) were found in samples from over half of patients (63%), most of whom (83%) also had villous blunting, mimicking celiac disease. Intraepithelial neutrophils were found in a subset (32%) and correlated with CMV and Cryptosporidium infections. Granulomas were seen in biopsies from 2 patients (11%). One patient had a collagenous enteritis pattern (accompanied by a collagenous colitis pattern). One patient had autoimmune enteritis; biopsies from this patient were initially relatively normal but later displayed prominent crypt apoptosis and loss of goblet cells. In colon samples, a paucity of plasma cells was seen in 10 patients (63%). The colon showed lymphoid aggregates in most patients (81%). Apoptosis was prominent in samples from half of the patients (50%). Biopsies from 6 patients had a lymphocytic colitis pattern (38%) and 2 patients had a collagenous colitis pattern. Intraepithelial neutrophils were found in samples from most patients (88%). Crypt distortion was seen in 6 of these patients (43%), thereby mimicking ulcerative or Crohn colitis. Granulomas were found in 3 patients (19%). CMV was detected in 1 patient. The appendix from 1 patient showed Cryptosporidium and acute serositis with a paucity of plasma cells and an increase in apoptosis. The gallbladder from 1 patient showed acute cholecystitis, and another patient's gallbladder lacked plasma cells.

CONCLUSIONS

GI tract CVID displays a wide spectrum of histologic patterns. Its features can mimic lymphocytic colitis, collagenous enterocolitis, celiac disease, lymphocytic gastritis, granulomatous disease, acute graft-versus-host disease, and inflammatory bowel disease. In fact, in our series, we found patients with a prior diagnosis of celiac disease (25%) and inflammatory bowel disease (35%), including Crohn disease (15%). The diagnosis of CVID may be suspected on the basis of the lack of plasma cells in a GI biopsy, but because this feature is only present in about two-thirds of patients, the diagnosis cannot always be suggested in isolation of other clinical and laboratory findings.

Helicobacter infection in the surfactant protein D-deficient mouse

BACKGROUND

Surfactant protein D (SP-D), a component of innate immunity, is expressed in the gastric mucosa and is up-regulated in the presence of Helicobacter infection. SP-D binds to Helicobacter in vitro, suggesting the involvement of SP-D in Helicobacter-induced immune responses. The aim of this study was to determine the role of SP-D in gastric epithelial defense in vivo.

METHODS

Specific pathogen-free SP-D-deficient mice (SP-D(-/-)) and C57BL/6 wild-type controls were challenged by gavage with different doses of Helicobacter felis, a mouse-adapted Helicobacter strain. Mice were assessed for colonization rates and density of infection. Inflammatory responses were measured by neutrophil counting and T-cell responses by proliferation assays on spleen cells stimulated with H. felis sonicate. The in vitro effect of SP-D on Helicobacter uptake by monocyte-derived dendritic cells was assessed by confocal microscopy and FACS analyses.

RESULTS

SP-D(-/-) mice were more susceptible to low-dose infectious challenge than C57BL/6 controls (p = .02). The density of colonization was higher in the SP-D(-/-) infected mice. Neutrophil infiltrates were lower in the SP-D(-/-) mice, particularly in the acid-secreting regions of the stomach. T-cell proliferative responses to Helicobacter antigen were reduced in SP-D(-/-) mice (p = .001) after 12 weeks infection. In vitro uptake of Helicobacter by dendritic cells was significantly enhanced in the presence of SP-D (p = .001).

CONCLUSION

In the absence of SP-D, Helicobacter uptake by dendritic cells is impaired. This provides an explanation for the diminished inflammation and immune responses in the SP-D(-/-) mice.

Helicobacter pylori-induced downregulation of the secretory leukocyte protease inhibitor (SLPI) in gastric epithelial cell lines and its functional relevance for H. pylori-mediated diseases

The secretory leukocyte protease inhibitor (SLPI) exerts antiproteolytic activity towards serine proteases, as well as anti-microbial and anti-inflammatory effects. To investigate its role in H. pylori-mediated diseases, SLPI expression was analyzed by RT-PCR, ELISA and immunohistochemistry in clinical samples and gastric tumor cell lines. Determination of the mucosal SLPI levels in 126 patients confirmed the previously reported downregulation of SLPI in H. pylori-infected patients. The lower SLPI levels in antral biopsies of H. pylori-positive subjects were associated with a 30-fold increase (p<0.01) in neutrophil elastase activity, and a significant negative correlation was demonstrated for both parameters (R=-0.63, p=0.0002). Eradication of the bacterium in a long-term study (5-7 years) led to a recovery of mucosal SLPI expression. In vitro experiments using four gastric tumor cell lines (AGS, MKN-28, MKN-45, NCI-N87) generally confirmed the clinical findings. While the co-incubation of these cell lines with H. pylori resulted in lower or unchanged SLPI protein levels, the corresponding SLPI mRNA amounts were upregulated by up to five-fold (p=0.006) in all cell lines. Taken together, these results indicate that the reduction in antral SLPI levels in H. pylori-infected subjects has a functional relevance for gastric mucosa and the H. pylori-induced decrease in SLPI is primarily regulated at the posttranslational level.

Immune responses to Helicobacter pylori colonization: mechanisms and clinical outcomes

Helicobacter pylori colonizes the stomachs of half of the world's population and usually persists in the gastric mucosa of human hosts for decades or life. Although most H. pylori-positive people are asymptomatic, the presence of H. pylori is associated with increased risk for the development of peptic ulcer disease, gastric adenocarcinoma and gastric lymphoma. The development of a sustained gastric inflammatory and immune response to infection appears to be pivotal for the development of disease. During its long co-existence with humans, H. pylori has evolved complex strategies to maintain a mild inflammation of the gastric epithelium while limiting the extent of immune effector activity. In this review, the nature of the host immune response to H. pylori infection and the mechanism employed by the bacterium to evade them is considered. Understanding the mechanisms of colonization, persistence and virulence factors of the bacterium as well as the innate and adaptive immune responses of the host are critically important for the development of new strategies to prevent the development of H. pylori-induced gastroduodenal disease.

The mechanism of heat-shock protein 70 gene expression abolition in gastric epithelium caused by Helicobacter pylori infection

BACKGROUND

The members of the family of heat shock factors coordinate the inducible transcription of heat shock genes in response to diverse stimuli. Any disturbances in signal transduction may lead to the attenuation of heat shock proteins synthesis and to cell death due to apoptosis. It has been shown by others that different nuclear factors, such as nuclear factor interleukin 6 or signal transducer and activator of transcription 3, co-operate with heat shock factors, mostly enhancing their activator effect on heat shock proteins genes expression. Therefore, we sought to determine whether apoptosis induced in the gastric epithelium exposed to live Helicobacter pylori might occur due to the elimination of HSP70 expression and deregulation of the heat shock response of the cell.

MATERIALS AND METHODS

Experiments were performed on KATO III gastric epithelial cells exposed to live cagA, vacA expressing Hp over different periods of time. Total cellular RNA, cytoplasmic and nuclear proteins were isolated for polymerase chain reaction, western-blot, electrophoretic mobility shift assay, decoy and co-immunoprecipitation studies.

RESULTS

We found that in human gastric epithelium exposed to Helicobacter pylori, heat shock factor 1 is bound and restrained in complexes by phosphorylated signal transducer and activator of transcription 3 protein. In consequence, heat shock factor 1 bound up with phosphorylated signal transducer and activator of transcription 3 protein is unable to activate HSP70 protein synthesis in KATO III cells under stress conditions. Helicobacter pylori also causes changes in bax/bcl-2 cellular equilibrium, leading to the induction of apoptosis.

CONCLUSIONS

The observed phenomenon might be the mechanism whereby gastric epithelium adapts to the infection of Helicobacter pylori, eliminating cells which are damaged or altered by bacterial cytotoxic products from the tissue.

Altered expression of Skp2, c-Myc and p27 proteins but not mRNA after H. pylori eradication in chronic gastritis

Helicobacter pylori infection is associated with increased gastric epithelial cell turnover and non-cardia gastric cancer. Cell cycle progression is dependent on the proteasomal degradation of p27, a cyclin-dependent kinase inhibitor and gastric tumor suppressor, following ubiquitination mediated by Skp2. c-Myc is a transcriptional repressor of p27 and also a target of Skp2. In vitro, H. pylori decreases p27 protein post-translationally. We aimed to determine how p27 is regulated by H. pylori in vivo. The effect of eradicating H. pylori on gastric epithelial p27, Skp2, and c-Myc proteins and mRNA was investigated in 22 patients with chronic gastritis, by immunohistochemistry and laser capture microdissection. The percentage of gastric antral epithelial cells expressing p27 protein was significantly higher after eradication of H. pylori (mean+/-s.e.m. 37+/-2.4% pre-eradication vs 55+/-2.8% post-eradication; P<0.001), while Skp2 and c-Myc protein-expressing cells were lower (Skp2: 35+/-3.8 vs 23+/-2.6%, P=0.009; c-Myc: 47+/-3.6 vs 30+/-3.8%, P<0.001). mRNA expressions of p27, Skp2, and c-Myc (normalized for 18SrRNA) were not changed by H. pylori eradication. H. pylori increases c-Myc and decreases gastric epithelial p27 protein expression in association with increased expression of Skp2, the regulator of p27's ubiquitin ligase complex. H. pylori may influence cell cycle progression and carcinogenesis through post-translational effects on specific gene expression.

Genetic variants in matrix metalloproteinase genes are associated with development of gastric ulcer in H. Pylori infection

BACKGROUND AND AIMS

Matrix metalloproteinases (MMPs) are a family of enzymes that degrade most of the macromolecules making up the extracellular matrix. H. pylori infection increases the secretion of MMPs in the gastric mucosa leading to severe mucosal damage. The aim of this study was to investigate if genetic variants in MMPs involved in the inflammatory response to H. pylori could predispose patients with chronic H. pylori infection to develop gastric ulcer disease.

METHODS

A total of 599 H. pylori-infected patients undergoing gastroscopy were genotyped for 20 SNPs covering the MMP-1, -3, -7, and -9 genes by TaqMan technology. Haplotype and single marker analysis was conducted to assess associations with gastric ulcer disease.

RESULTS

Carriage of allele G of the functional promoter variant MMP-7-181 was significantly associated with gastric ulcer conferring a 1.6-fold increased risk (95% CI: 1.0-2.6, p = 0.037). In addition, carriage of allele A of a coding SNP in exon 6 of MMP-9 confers a 2.4-fold increased risk (95% CI: 1.0-2.6, p = 0.013) for gastric ulcer.

CONCLUSION

The level of association found in this study is in agreement with the nature of a complex genetic disease. Genetic variations in the MMP-7 and -9 gene may be part of a complex genetic risk profile to develop gastric ulcer in chronic H. pylori infection. Further studies are warranted to elucidate the pathophysiological role of these genes in ulcerogenesis.

Concentrations of gastric mucosal cytokines in children with food allergy and Helicobacter pylori infection

AIM: To measure the concentrations of chosen cytokines in the antrum mucosa depending on the kind of harmful pathogenic factors and to compare the concentrations with the values of controls without allergy and coexisting Helicobacter pylori (H pylori) infection.

METHODS: The patients (97 children) were divided into three groups according to the data obtained from the case history, to the main cause of the disease and to the dominant clinical symptoms. Group I: children with food allergy (Fa); group II: children infected with H pylori; group III (control group): children with functional disorders of the alimentary tract (without Fa and Hp infection). H pylori infection was determined by the presence of anti-Hp antibodies in serum (ELISA method) and urease test performed during endoscopic examination. Cytokine concentration in homogenates of gastric mucosa was detected by ELISA method.

RESULTS: The IL-2 concentration in gastric mucosa bioptates was the highest in children with Hp infection (116.5±179.5 pg/mg of the protein) and Fa and Hp infection (98.1±101.0 pg/mg), while decreased in children with Fa (44.8±50.3 pg/mg) and controls (45.7±23.5 pg/mg). The lowest mean concentration of IFN-γ was observed in children with Hp infection (18.9±16.4 pg/mg), with Fa and Hp infection (25.5±27.7 pg/mg), with Fa (40.6±39.7 pg/mg) and controls (49.9±33.4 pg/mg). The highest IL-4 concentrations were observed in children with Hp infection (35.3±52.8 pg/mg) and in children with Fa and Hp infection (37.2±51.7 pg/mg), while lower IL-4 concentration (23.6±35.8 pg/mg) was found in children with Fa compared to the controls (22.7±13.8 pg/mg). The analysis of IL-4 concentrations in children with Hp infection regarding the intensity of gastritis showed the highest value (62.2±61.2 pg/mg) in mild and moderate gastritis. The concentrations of IL-5 in the gastric mucosa of children with or without Fa did not differ significantly and were comparable to the control group. The highest mean IL-8 value was observed in Hp-infected children with or without Fa. The highest concentration of mucosal IL-10 was detected in children with Hp infection (79.3±41.2 pg/mg) and decreased in children with Fa and Hp infection (50.1±18.8 pg/mg) and in children with Fa (39.9±35.5 pg/mg). The intensity and activity of the inflammation did not affect IL-10 concentrations in the gastric mucosa. In children with Hp infection, TNF-α concentration was the highest (45.9±49.3 pg/mg) and in children with Fa and Hp infection was low (45.3±32.6 pg/mg), whereas decreased in children with Fa (21.7±34.2 pg/mg) and in controls (31.6±14.5 pg/mg).

CONCLUSION: The morphological changes of the gastric mucosa in children with Hp infection are comparable to those in children with Fa and coexisting Hp infection. Cytokine concentration in children with Fa and Hp infection is significantly different in IFN-γ, IL-2, IL-8, and TNF-α.

Human immune response towards recombinant Helicobacter pylori urease and cellular fractions

Vaccination against Helicobacter pylori is of particular clinical interest. Recombinant urease, the major protein in H. pylori, has been used for mucosal vaccination trials in different animal models, but was found to be ineffective in humans. The current study therefore investigated the human immune response towards recombinant H. pylori urease A and B (rUreA/B) expressed in E. coli compared to different cellular fractions of H. pylori (cytosol, total, inner and outer membrane). Monocyte-derived dendritic cells (Mo-DC) were generated from monocytes isolated by magnetic antigen cell separation (MACS) from healthy volunteers and cultured in the presence of hrIL-4 and hrGM-CSF. Mo-DC were stimulated for 48h with the recombinant proteins (1 microg/ml) or cellular fractions (1-10 microg/ml) and cytokine release was determined in the culture supernatant by ELISA. rUreA and rUreB were effective in inducing IL-12 secretion (6-10 fold) and, to a much lesser extent (2 fold), IL-10 secretion from Mo-DC. Total and outer membrane preparations from H. pylori stimulated IL-12 secretion significantly, and were even more potent than intact bacteria. Mo-DCs pulsed with rUreA activated allogenic CD56+ NK-cells, as determined by TNF-alpha and IFN-gamma secretion, but not allogenic CD4+/CD45RA+ naïve T-cells. In contrast, Mo-DCs pulsed with H. pylori total membrane or outer membrane preparations activated allogenic naive T-cells in co-culture systems, as determined by increased TNF-alpha secretion. It appears that outer membrane preparations of H. pylori, but not recombinant urease are more effective in inducing a Th1 polarized response in humans in vitro.

Expressions of urokinase-type plasminogen activator, its receptor and plasminogen activator inhibitor-1 in gastric cancer cells and effects of Helicobacter pylori

OBJECTIVE

Destruction of the extracellular matrix is essential for tumor invasion and metastasis. The relationship between Helicobacter pylori (H. pylori) infection and destruction of the extracellular matrix is not yet clear. Urokinase-type plasminogen activator (uPA) plays an important role in the destruction of the extracellular matrix and basement membrane. Urokinase-type plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1(PAI-1) appear to be associated with these processes. To clarify the role of H. pylori infection in the processes of destruction of the extracellular matrix and basement membrane in cancerous tissue, the effect of H. pylori on the expressions of uPA, uPAR and PAI-1 in cancer cells was investigated.

MATERIALS AND METHODS

Gastric cancer cell lines (MKN45, KATO-III) were co-cultured with H. pylori standard strain (NCTC11637), cagA-negative strain and clinical isolated strain. The specific inductions of uPA, uPAR and PAI-1 mRNA were examined by reverse transcription-polymerase chain reaction (RT-PCR) amplification. The secreted uPA antigen was measured by enzyme-linked immunosorbent assay (ELISA). To evaluate the role of transcription factor NF-kappaB in uPA and uPAR gene transcription with H. pylori stimulation, the effect of NF-kappaB inhibitor MG132 on H. pylori-induced uPA and uPAR mRNA expression was examined.

RESULTS

The expressions of both uPA and uPAR mRNAs in the gastric cancer cell lines (MKN45 and KATO- III) were increased markedly (uPA mRNA; MKN45: 12-fold, KATO-III: 5-fold) (uPAR mRNA; MKN45: 3-fold, KATO-III: 3-fold) with H. pylori NCTC11637 strain stimulation, whereas the expression levels of uPA and uPAR mRNA did not increase with cagA-negative strain stimulation. These cancer cell lines slightly secreted uPA antigen into the culture medium, and the amount of uPA antigen increased dramatically by stimulation with H. pylori NCTC11637 and cagA-positive clinical isolated strains. These gastric cancer cell lines also slightly secreted PAI-1 antigen into the culture medium, and the amount of PAI-1 antigen was not affected by H. pylori NCTC11637 stimulation. H. pylori-induced uPA and uPAR mRNA expressions were strongly down-regulated by pretreatment with MG132 in both cell lines.

CONCLUSIONS

The results of this study indicated the possibility that cagA-positive H. pylori may play an important role not only in tissue remodeling, angiogenesis and wound healing but also in the process of degradation of the extracellular matrix breakdown, tumor invasion and metastasis by inducing uPA and uPAR complex in the gastric cancer cells.

Gastric mucosal cytokine levels in relation to host interleukin-1 polymorphisms and Helicobacter pyloricagA genotype

OBJECTIVE

The outcome of a Helicobacter pylori infection is related in part to interrelationships among H. pylori virulence factors and the H. pylori-induced mucosal response. The host inflammatory response is partly governed by polymorphisms in pro-inflammatory genes.

MATERIAL AND METHODS

Cytokine levels (interleukin (IL)-1beta, IL-6 and IL-8) were examined in H. pylori-infected and uninfected normal-appearing mucosa from patients with non-ulcer dyspepsia (NUD), margins of gastric ulcers and cancer tissues. Cytokine levels were compared with cagA genotypes and host interleukin (IL)-1 polymorphisms.

RESULTS

The study comprised 168 Thai patients. All infected patients possessed anti-CagA antibody. Gastric mucosal IL-8 levels were significantly higher in H.pylori-positive cases than in -negative cases in all three tissue types (e.g. 1115 versus 217 pg/mg protein for NUD) (p<0.001). Normal-appearing but H. pylori-infected antral mucosa of patients with cagA type 1a strains had higher IL-8 levels than those with type 2a strains (2632 versus 1036 pg/mg protein) (p<0.005). IL-1B-511T/T carriers had higher antral mucosal IL-1ss levels versus non-carriers (pg/mg protein) (T/T=221, T/C=178, C/C=70) (p=0.005). IL-1B-511T/T carriers also had higher IL-1beta levels versus non-carriers in H. pylori-negative patients.

CONCLUSIONS

It was found that both the host factors (IL-1 polymorphisms) and bacterial factors (cagA type 1a versus type 2a) influenced gastric mucosal cytokine levels. Future studies should concentrate on interactions among host factors (e.g. genetics and tissue responses) and bacterial and environmental factors.

Role of infectious diseases in human carcinogenesis

The burden of human infectious diseases remains a public health problem worldwide. At least 2 billion people are affected by viral infections, and a similar number by bacteria or helminths. The long-term effects of these maladies have raised particular concern since some infectious agents have been associated with chronic human diseases, especially cancer. It is estimated that 13-20% of the world cancer cases are associated with some virus, bacteria, or helminth, e.g., human papillomavirus, Helicobacter pylori, and Schistosoma haematobium that cause cervical, stomach, and urinary bladder cancer, respectively. Certain associations between infection and malignancy are strong and irrefutable; others are still speculative. This article reviews the infectious agents that have been associated with cancer and current knowledge about the mechanisms underlying these associations.

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

BACKGROUND

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

AIM

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

PATIENTS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Helicobacter pylori flagellins have very low intrinsic activity to stimulate human gastric epithelial cells via TLR5

Helicobacter pylori is a flagellated chronic pathogen, which colonizes the gastric mucus and mucosal cell surfaces. Flagella and motility are essential for the survival of this bacterium in the stomach environment. Flagellins of several bacterial species are potent activators of the human innate immune system by binding to TOLL-like receptor 5 (TLR5). The possible role of the two H. pylori flagellins FlaA and FlaB in stimulation of the innate immune system and induction of IL-8 release by human gastric epithelial cells was investigated in this study. Transcription and expression of TLR5 in three different human gastric epithelial cell lines was demonstrated. Salmonella enterica serovar Typhimurium FliC flagellin was able to activate human gastric epithelial cells. TLR5 transcription was modulated by H. pylori infection. However, both H. pylori flagellins appeared to possess no immunostimulatory potential on human gastric cells via TLR5, despite their extensive amino acid homology to stimulating flagellins of other bacterial species. The evolutionary development of such unique flagellins of low activating potential is proposed to be a novel mechanism of H. pylori to preserve the essential function of its flagella during chronic colonization of the stomach and to evade the deleterious host immune responses.

Gastritis associated with Helicobacter-like organisms in baboons

Subclinical gastritis was observed in 10 of 10 baboons (Papio spp.) from a toxicity study in a research facility. The lesions were similar in xenobiotic-treated and control animals, suggesting a spontaneous rather than chemical-induced disease. Histologic examination revealed lymphoplasmacytic gastritis in the antral mucosa. The fundic mucosa contained minor, scattered aggregates of lymphocytes and plasma cells. A Warthin-Starry silver stain and ultrastructural examination revealed numerous spiral-shaped bacteria morphologically resembling Helicobacter pylori in antral glands and numerous spiral-shaped bacteria morphologically consistent with H. heilmannii-like organisms in fundic glands. Polymerase chain reaction assay of paraffin-embedded antral and fundic tissue using primers for the urease gene and 16S ribosomal ribonucleic acid gene amplified deoxyribonucleic acid fragments with a high degree of sequence homology for H. pylori and H. heilmannii. This is the first report of gastritis associated with Helicobacter-like organisms in baboons.

Of blood and guts: association between Helicobacter pylori and the gastric microcirculation

The relative importance of acid in Helicobacter pylori (H. pylori) ulcer pathogenesis is in doubt, with possibilities existing that other contributing factors may be involved. Vascular insufficiency may lead to the development of ischemic lesions or ulcers within the gastric mucosa. H. pylori produces a striking inflammatory response following infection and one of the major components of gastrointestinal inflammation is alterations in the vascular structure and function. This suggests that the microcirculation may be a key target of H. pylori-released factors. Recent evidence has accumulated to suggest that H. pylori can affect a number of microcirculatory variables including blood flow, leukocyte activity and also induce changes in the endothelial lining of the vessels themselves. The majority of these findings have been described by employing the technique of fluorescent in vivo microscopy, which allows direct, dynamic and real time observations of the microcirculation to be made. A universal feature of these experimental studies has been the formation of circulating or adherent platelet aggregates. It is now recognized that platelets participate in the inflammatory response by acting as a potent source of inflammatory mediators and modulating the activity of other inflammatory cells. Circulation of platelet emboli may be of cause for concern, especially as a number of studies have demonstrated an association between H. pylori infection and coronary heart disease. The present review highlights the major findings from these studies and proposes an important role for the gastric microcirculation in the pathophysiology of H. pylori-induced injury.

Helicobacter pylori CagA status, mucosal oxidative damage and gastritis phenotype: a potential pathway to cancer?

BACKGROUND

Oxidative DNA damage is associated with Helicobacter pylori infection, atrophy and intestinal metaplasia. H. pylori-cagA-positive strains are associated with the highest risk of gastric cancer.

AIMS

To ascertain whether cagA-positive H. pylori infection correlates with higher concentrations of 8OHdG and the presence of precancerous changes.

PATIENTS AND METHODS

118 patients were studied (65M/53F, age 61 +/- 14 years). Twelve were H. pylori-negative. Among the H. pylori-positive patients, 34 were cagA-positive and 40 were cagA negative. In 32 patients H. pylori had been eradicated at least 6 months before endoscopic sampling. The phenotype of the gastritis (atrophic compared with nonatrophic, with and without intestinal metaplasia) was scored in biopsy samples obtained from the antrum, corpus, and angularis incisura. In antral biopsy samples, 8-hydroxydeoxyguanosine was assessed by HPLC (electrochemical detector). CagA status was determined by PCR.

RESULTS

The highest scores for both mononuclear inflammation and activity of gastritis were significantly associated with cagA status (p = 0.036 antrum and p = 0.02 corpus). cagA-positive infection significantly correlated with a higher prevalence of atrophic-metaplastic lesions (p = 0.04). cagA-positive patients had higher 8-hydroxydeoxyguanosine levels than both cagA-negative and H. pylori-negative cases (p = 0.01). The 8-hydroxydeoxyguanosine levels were significantly higher in multifocal atrophic gastritis (p = 0.04). The odds ratio for cagA-positive patients having 8OHdG levels above a cut-off calculated on the basis of the ROC curves were 7.12, overall, reaching 11.25 when only patients younger than 50 were considered.

CONCLUSIONS

cagA-positive patients were characterized: first, for higher scores for gastritis, activity and atrophic and metaplastic lesions; and second for greater oxidative DNA damage overall, at younger age and in the presence of multifocal atrophy. This setting may represent a cancer-prone biological context.

Helicobacter pylori virulence factors and the host immune response: implications for therapeutic vaccination

Helicobacter pylori colonizes the human gastric mucosa and is associated with specific gastric disease. Virulence factors, such as urease, the vacuolating toxin (VacA), the cytotoxin-associated antigen CagA or blood-group-antigen-binding adhesin (BabA), an adherence factor, might account for the development of different diseases. Vaccination trials exploiting the antigenic properties of some of these proteins have not been successful in preventing infection in humans. A more in-depth understanding of the immune response to H. pylori infection as well as additional information on suitable epitopes and adjuvants will be required before a successful vaccine can be developed.

Purification and relationship with gastric disease of a 130 kDa (CagA) protein of Helicobacter pylori

OBJECTIVE

The aims of this research were to purify and identify the 130 kDa (CagA) protein of H. pylori clinical isolate HP97002 and evaluate the relationships between the purified 130 kDa (CagA) protein and gastric diseases.

METHODS

The procedure for isolating the protein included 6 mol/L guanidine extract, size exclusion chromatography and elusion from gel. Sera of 68 patients with gastric diseases (44 with chronic gastritis, 15 with atrophic gastritis, 7 with peptic ulcer disease, 2 with gastric cancer) were obtained, and the serological response to CagA was studied by Western-blot using the purified protein.

RESULTS

The purified protein was 130 kDa and preserved good antigenicity and revealed basic isoelectric point about of 8.1. Among 68 sera, 43 sera could recognize the purified protein associated with chronic gastritis 47.7% (21/44), atrophic gastritis 86.7% (13/15), peptic ulcer disease 100% (77), gastric cancer 100% (2/2). Compared with each other, the difference was significant (chi2 = 13.327, P = 0.004), and 130 kDa (CagA) protein was associated with severe gastric diseases ( r(S) = 0.442, P = 0.001).

CONCLUSION

The 130 kDa (CagA) protein was associated with severe gastric diseases.

Catalase (KatA) and KatA-associated protein (KapA) are essential to persistent colonization in the Helicobacter pylori SS1 mouse model

Helicobacter pylori infects the human gastric mucosa and elicits an aggressive inflammatory response. Despite the severity of the inflammatory response, the bacterium is able to persist and cause a chronic infection. It is believed that antioxidant defence mechanisms enable this organism to persist. Wild-type H. pylori strain SS1, and KatA- and KapA-deficient mutants, were used to infect C57/BL6 mice to test this hypothesis. Neither KatA nor KapA was essential for the initial colonization of H. pylori SS1 in the murine model of infection. The wild-type SS1 colonized the gastric mucosa at significantly higher levels than both mutants throughout the 24-week experiment. Neither KatA- nor KapA-deficient mutants were able to maintain consistent ongoing colonization for the 24-week period, indicating the necessity of both KapA and KatA in sustaining a long-term infection. At 24 weeks, 5/10 mice inoculated with the KatA mutant and 2/10 mice inoculated with the KapA mutant were colonized, compared with 10/10 of the mice inoculated with the wild-type SS1. An increase in the severity of inflammation in the wild-type-inoculated mice appeared to correlate with the decline in colonization of animals inoculated with the mutants, suggesting that increased oxidative stress militated against continued infection by the mutants. These data indicate that KapA may be of equal or greater importance than KatA in terms of sustained infection on inflamed gastric mucosae.

Acid inhibitory potency of twice a day omeprazole is not affected by eradication of Helicobacter pylori in healthy volunteers

BACKGROUND AND AIMS

The acid inhibitory effect of proton pump inhibitors is reported to be greater in the presence than in the absence of an H. pylori infection. This study was undertaken to test the hypothesis that the acid inhibitory effect of omeprazole given twice a day is greater in H. pylori infected healthy volunteers than in the same individuals following eradication because of differences in the pharmacodynamics of omeprazole, greater duodenogastric reflux, the effects of ammonia produced by the H. pylori, or lower gastric juice concentrations of selected cytokines, which may inhibit gastric acid secretion.

MATERIALS AND METHODS

We undertook 24-hour pH-metry in 12 H. pylori-positive healthy volunteers: (1) when on no omeprazole; (2) when on omeprazole 20 mg bid for 8 days; (3) 2 months after eradication of H. pylori and when on no omeprazole; and (4) after eradication of H. pylori and when on omeprazole 20 mg twice a day.

RESULTS

In subjects given omeprazole, eradication of H. pylori reduced pH and percentage pH >or= 3, as well as increasing the area under the H+ concentration-time curve. These differences were not due to alterations in (1) gastric juice concentrations of IL-1alpha, IL-8, IL-13, epidermal growth factor, or bile acids; (2) serum gastrin concentrations; or (3) the pharmacokinetics of omeprazole. There was no change in the difference in the H+ concentration-time curve 'without omeprazole' minus 'with omeprazole', when comparing 'after' versus 'before' eradication of H. pylori.

CONCLUSIONS

Eradication of H. pylori was not associated with an alteration in the acid inhibitory potency when comparing the difference in gastric acidity 'with' versus 'without' omeprazole. When the results were expressed by simply taking into account the acid measurements while on omeprazole before versus after eradication of H. pylori, the acid inhibition with omeprazole was greater in the presence than in the absence of a H. pylori infection. The clinical significance of the small difference is not clear.

Helicobacter pylori strains expressing the vacuolating cytotoxin interrupt phagosome maturation in macrophages by recruiting and retaining TACO (coronin 1) protein

Recent evidence suggests that persistence of Helicobacter pylori can be explained, at least in part, by the failure of macrophages to kill bacteria. The fate of type 1 H. pylori strain LC11, which expresses the cag pathogenicity island (PAI) and the vacuolating cytotoxin, and type 2 strain LC20, which lacks both these virulence factors, was determined following infection of the murine macrophage cell line RAW 264.7 or the human macrophage-like cell line THP-1. Helicobacter pylori strain LC11 displayed enhanced survival in macrophages in comparison with strain LC20 (4.0 +/- 0.2 versus 2.1 +/- 0.6 log CFU ml-1, P < 0.01) at 24 h. Phagosomes containing strain LC11 showed reduced co-localization with LysoTracker Red, higher levels of expression of the early endosome marker EEA1 expression and lower expression of the late endosome/lysosome marker LAMP1 relative to internalized strain LC20, both at 2 h and 24 h. These findings indicate that, in contrast to strain LC20, strain LC11 resides in a compartment with early endosome properties and does not fuse with lysosomes. In addition, phagosomes containing LC11 recruited and retained a higher percentage of TACO (coronin 1) protein in comparison with phagosomes containing strain LC20. Furthermore, IFN-gamma stimulation facilitated maturation of phagosomes containing strain LC11 in association with the release of TACO and a reduction in bacterial survival. We have demonstrated through the use of isogenic cagA-, cagE-/picB- and vacA- mutant strains, that VacA plays a significant role in the interruption of the phagosome maturation. Taken together, these results indicate that, following phagocytosis, H. pylori strains expressing the vacuolating cytotoxin arrest phagosome maturation in association with the retention of TACO.