Helicobacter pylori antigen-specific T-cell responses at gastric level in chronic gastritis, peptic ulcer, gastric cancer and low-grade mucosa-associated lymphoid tissue (MALT) lymphoma

Clinical relevance of molecular aspects in extranodal marginal zone lymphoma: a critical appraisal

Extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is among the more common types of lymphoma accounting for up to 8% of newly diagnosed lymphoma cases. As opposed to other B-cell lymphomas, however, no predominant genetic hallmark has been defined in MALT lymphoma, but different localizations appear to be affected by different, sometimes distinct changes. Nonetheless, a high proportion of these genetic changes reported in MALT lymphomas dysregulate the pathways leading to NF-kB activation. t(11;18)(q21;q21)/BIRC3::MALT1 appears to be MALT lymphoma specific and is found in 24% of gastric and 40% of pulmonary MALT lymphomas. The translocation is associated with more disseminated disease in gastric MALT lymphoma and is found in a large percentage of patients whose lymphoma is unresponsive to antibiotic eradication of Helicobacter pylori. In addition to t(11;18)(q21;q21), nuclear expression of BCL10 or NF-kB appears to be highly associated with lymphoma cell survival independence of H. pylori-mediated stimulations. Antibiotic eradication, however, is the recommended therapy of choice irrespective of genetic findings, and molecular analysis is not required before initiation of therapy. The influence of genetic translocations including t(11;18)(q21;q21) on systemic therapies, however, is less clearly defined. While small series have shown no influence on the outcome for treatment with the anti-CD20 antibody rituximab (R) or treatment with cladribine (2-CdA), conflicting data have been reported for alkylating agents, especially chlorambucil and the combination of R + chlorambucil. None of other genetic changes seen in MALT lymphoma to date has discernible value in routine clinical applications, but recent data suggest that changes in TNFAIP3(A20), KMTD2 and CARD11 might be associated with response to Bruton kinase inhibitors.

In vitro transcytosis of Helicobacter pylori histidine-rich protein through gastric epithelial-like cells and the blood-brain barrier

Recent epidemiological studies have supported the correlation between Helicobacter pylori infection and the development of Alzheimer's disease. HpHpn, a histidine-rich H. pylori protein, forms amyloid-like oligomers; it may be a pathogenic factor for Alzheimer's disease progression. HpHpn may also be transported from the gastric epithelium to the brain. However, HpHpn is secreted from H. pylori on the outer surface of gastric epithelia; therefore, the hypothesized movement of HpHpn across the gastric epithelium to the blood remains controversial. Here, we found the HpHpn showed acidic pH-dependent cellular uptake and subsequent secretion in human gastric epithelial-like carcinoma cells. Furthermore, HpHpn exhibited in vitro permeability across the blood-brain barrier. Although further in vivo experiments are required, our findings suggest that in vitro transcytosis of HpHpn in gastric epithelial cells and the blood-brain barrier may provide new insights into the correlation between H. pylori infections and Alzheimer's disease progression.

Helicobacter pylori cagA status and gastric mucosa-associated lymphoid tissue lymphoma: a systematic review and meta-analysis

Background

Recent studies have investigated the role of Helicobacter pylori infection in the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma. It is estimated that approximately 0.1% of people infected with H. pylori develop gastric MALT lymphoma. However, the role of the CagA antigen, the highest causative agent of H. pylori, in increasing the risk of gastric MALT lymphoma remains unclear and controversial. A systematic review and meta-analysis were conducted to evaluate the effect of cagA status on the development of gastric MALT lymphoma.

Methods

All articles evaluating the status of the cagA gene in the development of gastric MALT lymphoma were collected using systematic searches in online databases, including PubMed, Scopus, Embase, and Google Scholar, regardless of publication date. The association between cagA and gastric MALT lymphoma was assessed using the odds ratio (OR) summary. In addition, a random-effects model was used in cases with significant heterogeneity.

Results

A total of 10 studies met our inclusion criteria, among which 1860 patients participated. No association between cagA status and the development of MALT lymphoma (extranodal marginal zone B-cell lymphoma) was found in this study (OR 1.30; 0.906–1.866 with 95% CIs; I²: 45.83; Q-value: 12.92). Surprisingly, a meaningful association was observed between cagA status and diffuse large B-cell lymphoma (OR 6.43; 2.45–16.84 with 95% CIs). We also observed an inverse association between vacA and gastric MALT lymphoma risk (OR 0.92; 0.57–1.50 with 95% CIs).

Conclusions

It seems that the infection with cagA-positive H. pylori strains does not have a meaningful effect on the gastric MALT lymphoma formation, while translocated CagA antigen into the B cells plays a crucial role in the development of diffuse large B-cell lymphoma.

Pernicious anemia: Pathophysiology and diagnostic difficulties

Pernicious anemia (PA) is the most common cause of vitamin B12 (cobalamin) deficiency anemia in the world. It is an autoimmune disease, comprising of salient features of autoimmune chronic atrophic gastritis (CAG) and cobalamin deficiency (CD). Although the anemia was first described as pernicious, it may well be controlled with vitamin B12 replacement. The onset and progression of PA is often insidious. Alternatively, patients may have no anemic symptoms since they become acclimatized to the subtle nature of the disease. Oftentimes, there is a possibility that the underlying disease may be missed unless a full blood count (FBC) is investigated, leading to hindrance in the treatment journey. Diagnostic challenges remain tangible for many practicing clinicians, since there is lack of reliable cobalamin assays to diagnose CD as well as clinical mimics, which simulate many other hematological conditions, such as myelodysplastic syndrome, acute leukemia, sideroblastic anemias, bone marrow failure states, thrombotic microangiopathy, and thromboembolism. Moreover, prompt recognition of the symptoms of CD is also vital, because some neurologic sequalae may become irreversible despite replenishing cobalamin. Herein, we discuss a literature review on the pathophysiology, challenging clinical presentations and diagnostic difficulties of PA. Since the cobalamin replacement therapy for PA is straightforward, it will not be discussed in this review.

Notch 1 Is Involved in CD4+ T Cell Differentiation Into Th1 Subtype During Helicobacter pylori Infection

Helicobacter pylori infection induces CD4⁺ T differentiation cells into IFN-γ-producing Th1 cells. However, the details of mechanism underlying this process remain unclear. Notch signal pathway has been reported to regulate the differentiation of CD4⁺ T cells into Th1 subtype in many Th1-mediated inflammatory disorders but not yet in H. pylori infection. In the present study, the mRNA expression pattern of CD4⁺ T cells in H. pylori-infected patients differed from that of healthy control using Human Signal Transduction Pathway Finder RT2 Profiler PCR Array, and this alteration was associated with Notch signal pathway, as analyzed by Bioinformation. Quantitative real-time PCR showed that the mRNA expression of Notch1 and its target gene Hes-1 in CD4⁺ T cells of H. pylori-infected individuals increased compared with the healthy controls. In addition, the mRNA expression of Th1 master transcription factor T-bet and Th1 signature cytokine IFN-γ was both upregulated in H. pylori-infected individuals and positively correlated with Notch1 expression. The increased protein level of Notch1 and IFN-γ were also observed in H. pylori-infected individuals confirmed by flow cytometry and ELISA. In vitro, inhibition of Notch signaling decreased the mRNA expression of Notch1, Hes-1, T-bet, and IFN-γ, and reduced the protein levels of Notch1 and IFN-γ and the secretion of IFN-γ in CD4⁺ T cells stimulated by H. pylori. Collectively, this is the first evidence that Notch1 is upregulated and involved in the differentiation of Th1 cells during H. pylori infection, which will facilitate exploiting Notch1 as a therapeutic target for the control of H. pylori infection.

The Gastrointestinal Tumor Microenvironment: An Updated Biological and Clinical Perspective

Gastrointestinal cancers are still responsible for high numbers of cancer-related deaths despite advances in therapy. Tumor-associated cells play a key role in tumor biology, by supporting or halting tumor development through the production of extracellular matrix, growth factors, cytokines, and extracellular vesicles. Here, we review the roles of these tumor-associated cells in the initiation, angiogenesis, immune modulation, and resistance to therapy of gastrointestinal cancers. We also discuss novel diagnostic and therapeutic strategies directed at tumor-associated cells and their potential benefits for the survival of these patients.

Identification of Two Lpp20 CD4+ T Cell Epitopes in Helicobacter pylori-Infected Subjects

Antigen-specific CD4⁺ T cells play an essential role in effective immunity against Helicobacter pylori (H. pylori) infection. Lpp20, a conserved lipoprotein of H. pylori, has been investigated as one of major protective antigens for vaccination strategies. Our previous study identified two H-2^d-restricted CD4⁺ T cell epitopes within Lpp20 and an epitope vaccine based on these epitopes was constructed, which protected mice in prophylactic and therapeutic vaccination against H. pylori infection. Immunodominant CD4⁺ T cell response is an important feature of antiviral, antibacterial, and antitumor cellular immunity. However, while many immunodominant HLA-restricted CD4⁺ T cell epitopes of H. pylori protective antigens have been identified, immunodominant HLA-restricted Lpp20 CD4⁺ T cell epitope has not been elucidated. In this study, a systematic method was used to comprehensively evaluate the immunodominant Lpp20-specific CD4⁺ T cell response in H. pylori-infected patients. Using in vitro recombinant Lpp20 (rLpp20)-specific expanded T cell lines from H. pylori-infected subjects and 27 18mer overlapping synthetic peptides spanned the whole Lpp20 protein, we have shown that L_55-72 and L_79-96 harbored dominant epitopes for CD4⁺ T cell responses. Then the core sequence within these two 18mer dominant epitopes was screened by various extended or truncated 13mer peptides. The immunodominant epitope was mapped to L_57-69 and L_83-95. Various Epstein-Barr virus (EBV) transformed B lymphoblastoid cell lines (B-LCLs) with different HLA alleles were used as antigen presenting cell (APC) to present peptides to CD4⁺ T cells. The restriction molecules were determined by HLA class-antibody blocking. L_57-69 was restricted by DRB1-1501 and L_83-95 by DRB1-1602. The epitopes were recognized on autologous dendritic cells (DCs) loaded with rLpp20 but also those pulsed with whole cell lysates of H. pylori (HP-WCL), suggesting that these epitopes are naturally processed and presented by APC. CD4⁺ T cells were isolated from H. pylori-infected patients and stimulated with L_57-69 and L_83-95. These two epitopes were able to stimulate CD4⁺ T cell proliferation. This study may be of value for the future development of potential H. pylori vaccine.

Helicobacter pylori-derived heat shock protein 60 increases the induction of regulatory T-cells associated with persistent infection

Local Treg responses are involved in Helicobacter pylori-related inflammation and clinical outcomes after infection, and H. pylori-derived HSP60 (HpHSP60) is an important virulence factor associated with gastric carcinogenesis. This study to investigate the role of HpHSP60 in immunosuppression, particularly with regard to whether it could induce the production of Treg cells. For this purpose, human peripheral blood mononuclear cells (PBMCs) were treated with or without HpHSP60 in the presence of an anti-CD3 mAb to determine the effect of HpHSP60 on cell proliferation. In this report, HpHSP60 decreased the expression of CDK4 to significantly arrest the proliferation of mitogen-stimulated T-cells, which correlated with the induction of Treg cells. Moreover, monocytic cells were essential for the induction of HpHSP60-induced Treg cells via the secretion of IL-10 and TGF-β after treatment with HpHSP60. Blockage of HpHSP60 with specific monoclonal antibodies significantly reduced the colonization of H. pylori and the expression of Treg cells in vivo. Overall, our results suggest that HpHSP60 could act on macrophages to trigger the expression of IL-10 and TGF-β, thereby leading to an increase in Treg cells and inhibition of T-cell proliferation.

T cell subsets play an important role in the determination of the clinical outcome of Helicobacter pylori infection

Helicobacter pylori (H. pylori) is one of the most prevalent human pathogen and a persistent infection with this bacterium causes common pathologies, such as gastritis or peptic ulcers, and also less common but more serious pathologies, such as gastric cancer or gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The clinical outcome of gastrointestinal infection sustained by H. pylori is determined by the reciprocal interactions between virulence factors of the bacterium and host factors, including immune response genes. Although H. pylori induces a strong immune response, the bacterium is not eliminated. The eradication failure could be attributed to the bacterial capability to regulate helper T (Th) cell-related responses. H. pylori specific CD4⁺ T cells play a fundamental role in regulating host immunity and immunopathologic events. It has been documented that Th1, Th2, Th9, Th17, Th22 and T regulatory (Treg) cells, separately or in coordination with each other, can affect the outcome of the infection sustained by of H. pylori. Some studies indicated that both Th1 and Th17 cells may be protective or pathogenic, whereas Treg and Th2 cells perform anti-inflammatory impacts during H. pylori infection. This review gathers recent information regarding the association of the CD4⁺ T cells-mediated immunological responses and the clinical consequence of H. pylori infection.

Regulatory T cells may participate in Helicobacter pylori persistence in gastric MALT lymphoma: lessons from an animal model

It has been postulated that the emergence of autoimmune gastritis in neonatal thymectomised (d3Tx) BALB/c mice may be a consequence of post-surgery deficit in Tregs. In this study, previously obtained samples from d3Tx mice were used in order to determine whether thymectomy creates a deficit in this T cell subset thereby allowing the emergence of autoimmune phenomena as a prerequisite for GML. The splenic Treg reserve and the local recruitment of these cells in the gastric mucosa were investigated using complementary molecular and immunohistochemistry approaches. Higher Foxp3/CD3 ratios were found in the spleen of non-infected d3Tx mice compared to non-thymectomised (NTx) controls. These results indicate a relative enrichment of Tregs following thymectomy in adult mice. The absence of Treg depletion in d3Tx mice is in line with the absence of auto-immune gastritis in non-infected d3Tx mice. Higher levels of T cell and Treg infiltration were also found in the stomach of GML-developing d3Tx mice versus NTx mice. Surprisingly, inflammatory scores inversely correlated with the bacterial inoculum. The presence of a small Treg containing compartment among gastric biopsies of GML developing d3Tx mice may play a role in perseverance of a minimal bacterial numbers thereby maintaining an antigen-dependent stimulation and proliferation.

Characterisation of inflammatory processes in Helicobacter pylori-induced gastric lymphomagenesis in a mouse model

Gastric MALT lymphoma (GML) can be induced by Helicobacter pylori infection in BALB/c mice thymectomised at day 3 post-birth (d3Tx). This represented a unique opportunity to investigate the inflammatory process involved in the recruitment, proliferation and structuration of lymphoid infiltrates in the gastric mucosa of mice developing GML. Complementary molecular and proteomic approaches demonstrated that Th1 and Th2 cytokines were upregulated, along with activators/regulators of the lymphoid response and numerous chemokines. Interleukin-4, interferon γ, lymphotoxin-α and -β were significantly upregulated and correlated with the inflammatory scores for all the d3Tx mice. GML lesions in d3Tx mice infected with H. pylori were associated with the presence of the inflammatory response. The dysregulation of numerous members of the tumour necrosis factor superfamily was also evident and suggests that they could play an important role in GML pathology, especially in light of their ability to promote and control lymphocyte proliferation.

Omeprazole Induces Apoptosis in Jurkat Cells

We report for the first time a potent apoptotic effect of omeprazole (OM). Apoptosis was induced in Jurkat cells in a time and concentration-dependent mode. Caspase 3 and PARP were rapidly cleaved in response to OM, but apoptosis was only partially inhibited by the caspase 3 inhibitor DEVD-CHO. OM also induced an early lysosomal destabilization which increased progressively and was correlated with a parallel increase in apoptotic cells. The cysteine protease inhibitor E64d gave strong protection against apoptosis thus proving the involvement of lysosomal enzymes in OM-induced apoptosis whereas, it did not impede the caspase 3 cleavage. Instead ZVAD-fmk, a general caspase inhibitor, also able to inhibit cathepsin activity, protected cells completely from OM-induced apoptosis. It therefore seems that both caspases and cysteine cathepsins are involved in the execution stage of OM-induced apoptosis.

Immunomodulation and anti-inflammatory effects of garlic compounds

The benefits of garlic to health have been proclaimed for centuries; however, only recently have Allium sativum and its derivatives been proposed as promising candidates for maintaining the homeostasis of the immune system. The complex biochemistry of garlic makes it possible for variations in processing to yield different preparations with differences in final composition and compound proportion. In this review, we assess the most recent experimental results, which indicate that garlic appears to enhance the functioning of the immune system by stimulating certain cell types, such as macrophages, lymphocytes, natural killer (NK) cells, dendritic cells, and eosinophils, by mechanisms including modulation of cytokine secretion, immunoglobulin production, phagocytosis, and macrophage activation. Finally, because immune dysfunction plays an important role in the development and progress of several diseases, we critically examined immunoregulation by garlic extracts and compounds isolated, which can contribute to the treatment and prevention of pathologies such as obesity, metabolic syndrome, cardiovascular disorders, gastric ulcer, and even cancer. We concluded that A. sativum modulates cytokine secretion and that such modulation may provide a mechanism of action for many of their therapeutic effects.

Can Helicobacter pylori infection influence human reproduction?

Helicobacter pylori (H. pylori) infection could be associated with extra-digestive diseases. Here, we report the evidences concerning the decrease in reproductive potential occurring in individuals infected by H. pylori, especially by strains expressing CagA. This infection is more prevalent in individuals with fertility disorders. Infected women have anti-H. pylori antibodies in cervical mucus and follicular fluid that may decrease sperm motility and cross react immunologically with spermatozoa, conceivably hampering the oocyte/sperm fusion. Infection by CagA positive organisms enhances the risk of preeclampsia, which is a main cause of foetus death. These findings are supported by the results of experimental infections of pregnant mice, which may cause reabsorption of a high number of foetuses and alter the balance between Th1 and Th2 cell response. Infected men have decreased sperm motility, viability and numbers of normally shaped sperm and augmented systemic levels of inflammatory cytokines, such as tumor necrosis factor-α, which may damage spermatozoa. In countries where parasitic infestation is endemic, detrimental effects of infection upon spermatozoa may not occur, because the immune response to parasites could determine a switch from a predominant Th1 type to Th2 type lymphocytes, with production of anti-inflammatory cytokines. In conclusion, the evidences gathered until now should be taken into consideration for future studies aiming to explore the possible role of H. pylori infection on human reproduction.

Helicobacter pylori CagA: From Pathogenic Mechanisms to Its Use as an Anti-Cancer Vaccine

Helicobacter pylori colonizes the gastric mucosa of more than 50% of the human population, causing chronic inflammation, which however is largely asymptomatic. Nevertheless, H. pylori-infected subjects can develop chronic gastritis, peptic ulcer, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. Chronic exposure to the pathogen and its ability to induce epithelial to mesenchymal transition (EMT) through the injection of cytotoxin-associated gene A into gastric epithelial cells may be key triggers of carcinogenesis. By deregulating cell-cell and cell-matrix interactions as well as DNA methylation, histone modifications, expression of micro RNAs, and resistance to apoptosis, EMT can actively contribute to early stages of the cancer formation. Host response to the infection significantly contributes to disease development and the concomitance of particular genotypes of both pathogen and host may turn into the most severe outcomes. T regulatory cells (Treg) have been recently demonstrated to play an important role in H. pylori-related disease development and at the same time the Treg-induced tolerance has been proposed as a possible mechanism that leads to less severe disease. Efficacy of antibiotic therapies of H. pylori infection has significantly dropped. Unfortunately, no vaccine against H. pylori is currently licensed, and protective immunity mechanisms against H. pylori are only partially understood. In spite of promising results obtained in animal models of infection with a number of vaccine candidates, few clinical trials have been conducted so far and with no satisfactory outcomes. However, prophylactic vaccination may be the only means to efficiently prevent H. pylori-associated cancers.

The association of interleukin-18 promoter polymorphisms and serum levels with duodenal ulcer, and their correlations with bacterial CagA and VacA virulence factors

BACKGROUND

We analyzed the impact of interleukin (IL)-18 promoter polymorphisms on IL-18 serum levels in Helicobacter pylori-infected duodenal ulcer (DU) patients and healthy asymptomatic (AS) carriers. We also aimed to determine the association of the H. pylori virulence factors CagA and VacA antibodies with serum concentrations of IL-18 in order to elucidate any correlation between them.

METHODS

Three groups of patients were enrolled: DU patients (67 individuals), AS carriers (48 individuals), and H. pylori-negative subjects (26 individuals). Serum concentrations of IL-18 were determined by ELISA. Patient sera were tested by Western blot method to determine the presence of serum antibodies to bacterial CagA and VacA. Genotyping of IL-18 promoter polymorphisms at positions - 137G/C and - 607C/A were performed by allele-specific primer PCR protocol.

RESULTS

Our study revealed that serum IL-18 levels are positively influenced by CagA-positive H. pylori strains, so that maximum levels of IL-18 were detected in DU patients with the CagA(+) phenotype, regardless of the presence of the anti-VacA antibody. Regarding IL-18 promoter polymorphisms, the AA genotype and A allele at position - 607C/A were found to be significantly lower in DU patients than in AS carriers and H. pylori-negative subjects (p = 0.032 and 0.043, respectively).

CONCLUSIONS

The IL-18 - 607C variant was associated with higher levels of serum IL-18 and an increased risk of DU. Moreover, our findings indicated that serum concentrations of IL-18 were influenced by CagA factor, irrespective of the VacA status, suggesting that high levels of IL-18 in CagA-positive subjects predisposes to susceptibility to DU.

A dominant CD4(+) T-cell response to Helicobacter pylori reduces risk for gastric disease in humans

BACKGROUND & AIMS

Immunodominance is an important feature of antiviral, antitumor, and antibacterial cellular immune responses, but it is not well demonstrated in the immune responses against Helicobacter pylori. Antigen-specific CD4(+) T cells protect mice against infection with H pylori. We investigated the immunodominant CD4(+) T-cell response to neuraminyllactose-binding hemagglutinin (HpaA), which is a conserved, H pylori-specific colonization factor that is being investigated as an antigen for vaccination strategies.

METHODS

HpaA-specific CD4(+) T cells were expanded with autologous peripheral blood mononuclear cells that had been incubated with recombinant HpaA and characterized using overlapping synthetic peptides. We compared the percentage of CD4(+) T cells with specificity for HpaA(88-100), restricted to HLA-DRB1*1501, among 59 H pylori-infected subjects with different gastric diseases.

RESULTS

We identified and characterized several immunodominant CD4(+) T-cell epitopes derived from HpaA. The immunodominant CD4(+) T-cell responses specific to HpaA(88-100) were observed in most H pylori-infected individuals who expressed HLA-DRB1*1501 and were significantly more abundant in patients with less severe diseases (P < .05).

CONCLUSIONS

The HLA-DRB1*1501-restricted immunodominant CD4(+) T-cell response to HpaA(88-100) is associated with reduced risk of severe gastric diseases. Further study of these and other immunodominant CD4(+) T-cell responses to H pylori will provide insight into mechanisms of protective immunity and aid in vaccine design.

Preserved gastric motility in patients with early gastric cancer after endoscopic submucosal dissection

BACKGROUND AND AIM

Endoscopic submucosal dissection (ESD) is now accepted as a minimally invasive treatment for early gastric cancer (EGC). To our knowledge, however, the functional effects of ESD have not been determined in patients with EGC. We therefore investigated whether gastric motility was affected by ESD.

METHODS

Using the (13) C-octanoic acid breath test, gastric emptying of solid test meals was examined in 26 EGC patients and 18 healthy controls, with EGC patients assayed before and about 2 months after ESD. Based on (13) CO2 breath-excretion curves, the lag-phase time (T(lag) ), half-emptying time (T(1/2) ), and gastric emptying coefficient (GEC) were calculated as indices of gastric emptying.

RESULTS

In healthy controls, the mean T(lag), T(1/2), and GEC were 85.5 ± 4.9 min, 148.5 ± 8.0 min, and 3.01 ± 0.09 h, respectively. Before ESD, the mean T(lag) , T(1/2), and GEC in the EGC patients were 90.1 ± 5.5 min, 174.7 ± 10.4 min, 2.64 ± 0.08 h, respectively. GEC, but not T(lag) or T(1/2), differed significantly in the two groups, with gastric emptying slower in EGC patients than in controls. Relative to before ESD, the mean T(lag), T(1/2), and GEC in EGC patients after ESD were 109.2% ± 7.8%, 107.9% ± 9.6%, 108.4% ± 4.7%, respectively, indicating that ESD did not significantly affect any of these gastric emptying parameters in EGC patients.

CONCLUSION

ESD is an effective treatment for EGC both in preserving organs and gastric motility.

Polymorphisms of the DNA methyltransferase 1 associated with reduced risks of Helicobacter pylori infection and increased risks of gastric atrophy

INTRODUCTION

DNA methyltransferase-1(DNMT1) is an important enzyme in determining genomic methylation patterns in mammalian cells. We investigated the associations between SNPs in the DNMT1 gene and risks of developing H. pylori seropositivity, gastric atrophy and gastric cancer in the Chinese population.

METHODS

The study consisted of 447 patients with gastric cancer; 111 patients with gastric atrophy; and 961 healthy controls. Five SNPs, rs10420321, rs16999593, rs8101866, rs8111085 and rs2288349 of the DNMT1 gene were genotyped. Anti-H.pylori IgG was detected by ELISA. Gastric atrophy was screened by the level of serum pepsinogen Ι and II and then confirmed by endoscopy and histopatholgical examinations.

RESULTS

The age- and sex-adjusted OR of H. pylori seropositivity was 0.67 (95%CI: 0.51-0.87) for rs8111085 TC/CC genotypes, significantly lower than the TT genotype in healthy controls. The adjusted OR of H.pylori seropositivity was 0.68 (95%CI: 0.52-0.89) for rs10420321 AG/GG genotypes. In addition, patients carrying rs2228349 AA genotype have a significantly increased risk for H.pylori seropositivity (OR=1.67; 95%CI: 1.02-2.75). Further haplotype analyses also showed that the ATTTG and ATCTA are significantly associated with increased risks in H.pylori infection compared to the GTCCG haplotype (OR=1.38, 95%CI: 1.08-1.77; OR=1.40, 95% CI: 1.09-1.80). The adjusted ORs of gastric atrophy were 1.66 (95%CI: 1.06-2.61) for rs10420321 GG genotype, and 1.67 (95%CI 1.06-2.63, P=0.03) for rs8111085 CC genotype, but no association was found between SNPs in the DNMT1 gene and risk of developing gastric cancer.

CONCLUSIONS

Individuals with rs10420321 GG and rs8111085 CC genotype of the DNMT1 gene were associated with reduced risks for H.pylori infection. On the other hand, higher risks of gastric atrophy were found in the carriers with these two genotypes compared to other genotypes. Our results suggested that SNPs of DNMT1 could be used as genotypic markers for predicting genetic susceptibilities to H.pylori infection and risks in gastric atrophy.

T cells in gastric cancer: friends or foes

Gastric cancer is the second cause of cancer-related deaths worldwide. Helicobacter pylori is the major risk factor for gastric cancer. As for any type of cancer, T cells are crucial for recognition and elimination of gastric tumor cells. Unfortunately T cells, instead of protecting from the onset of cancer, can contribute to oncogenesis. Herein we review the different types, “friend or foe”, of T-cell response in gastric cancer.

T cells and adoptive immunotherapy: recent developments and future prospects in gastrointestinal oncology

Gastrointestinal oncology is one of the foremost causes of death: the gastric cancer accounts for 10.4% of cancer deaths worldwide, the pancreatic cancer for 6%, and finally, the colorectal cancer for 9% of all cancer-related deaths. For all these gastrointestinal cancers, surgical tumor resection remains the primary curative treatment, but the overall 5-year survival rate remains poor, ranging between 20-25%; the addition of combined modality strategies (pre- or postoperative chemoradiotherapy or perioperative chemotherapy) results in 5-year survival rates of only 30-35%. Therefore, many investigators believe that the potential for making significant progress lies on understanding and exploiting the molecular biology of gastrointestinal tumors to investigate new therapeutic strategies such as specific immunotherapy. In this paper we will focus on recent knowledge concerning the role of T cells and the use of T adoptive immunotherapy in the treatment of gastrointestinal cancers.

Tumor-associated macrophages as major source of APRIL in gastric MALT lymphoma

Lymphoid hyperplasia of gastric mucosa associated with Helicobacter pylori (HP) infection represents a preneoplastic condition of the mucosa associated lymphoid tissue (MALT), which may evolve to a B-cell lymphoma. While it is well established that the initial neoplastic proliferation of B cells is antigen-driven and dependent on the helper activity of HP-specific T cells, it needs to be elucidated which cytokine or soluble factor(s) promote B-cell activation and lymphomagenesis. Herein, we originally report that gastric MALT lymphoma express high levels of a proliferation inducing ligand (APRIL), a novel cytokine crucial in sustaining B-cell proliferation. By immunohistochemistry, we demonstrate that APRIL is produced almost exclusively by gastric lymphoma-infiltrating macrophages located in close proximity to neoplastic B cells. We also show that macrophages produce APRIL on direct stimulation with both HP and HP-specific T cells. Collectively, our results represent the first evidence for an involvement of APRIL in gastric MALT lymphoma development in HP-infected patients.

Helicobacter pylori stimulates dendritic cells to induce interleukin-17 expression from CD4+ T lymphocytes

Helicobacter pylori is a human gastroduodenal pathogen that leads to active chronic inflammation characterized by T-cell responses biased toward a Th1 phenotype. It has been accepted that H. pylori infection induces a Th17 response. At mucosal sites, dendritic cells (DCs) have the capacity to induce effector T cells. Here, we evaluate the role of DCs in the H. pylori-induced interleukin-17 (IL-17) response. Immunohistochemistry and immunofluorescence were performed on human gastric mucosal biopsy samples and showed that myeloid DCs in H. pylori-infected patients colocalized with IL-23- and that IL-17-producing lymphocytes were present in H. pylori-infected antral biopsy samples. In parallel, human monocyte-derived DCs stimulated in vitro with live H. pylori cells produced significant levels of IL-23 in the absence of IL-12 release. The subsequent incubation of H. pylori-infected DCs with autologous CD4(+) T cells led to gamma interferon (IFN-gamma) and IL-17 expression. The inhibition of IL-1 and, to a lesser extent, IL-23 inhibited IL-17 production by T cells. Finally, isogenic H. pylori mutant strains not expressing major virulence factors were less effective in inducing IL-1 and IL-23 release by DCs and IL-17 release by T cells than parental strains. Altogether, we can conclude that DCs are potent inducers of IL-23/IL-17 expression following H. pylori stimulation. IL-1/IL-23 as well as H. pylori virulence factors seem to play an important role in mediating this response.

Helicobacter pylori: phenotypes, genotypes and virulence genes

Helicobacter pylori is a Gram-negative, microaerophilic bacterium that colonizes the gastric mucus overlying the epithelium of the stomach in more than 50% of the world's population. This gastric colonization induces chronic gastric inflammation in all infected individuals, but only induces clinical diseases in 10-20% of infected individuals. These include peptic ulcers, acute and atrophic gastritis, intestinal metaplasia, gastric adenocarcinoma and gastric B-cell lymphoma. Various bacterial virulence factors are associated with the development of such gastric diseases, and the characterization of these markers could aid medical prognosis, which could be extremely important in predicting clinical outcomes. The purpose of this review is to summarize the role of the phenotypes, virulence-related genes and genotypes of H. pylori in the establishment of gastric colonization and the development of associated diseases.

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.

Conventional, regulatory, and unconventional T cells in the immunologic response to Helicobacter pylori

Infection by the gastroduodenal pathogen Helicobacter pylori elicits a complex immunologic response in the mucosa involving neutrophils, plasma cells, eosinophils, and lymphocytes, of which T cells are the principal orchestrators of immunity. While so-called classical T cells (e.g. T-helper cells) that are activated by peptide fragments presented on antigen-presenting cells have received much attention in H. pylori infection, there exists a diverse array of other T cell populations that are potentially important for the outcome of the ensuing immune response, some of which have not been extensively studied in H. pylori infection. Pathogen-specific regulatory T cells that control and prevent the development of immunopathology associated with H. pylori infection have been investigated, but these cells can also benefit the bacterium in helping to prolong the chronicity of the infection by suppressing protective immune responses. An overlooked T cell population, the more recently described Th17 cells, may play a role in H. pylori-induced inflammation, due to triggering responses that ultimately lead to the recruitment of polymorphs, including neutrophils. The so-called innate or unconventional T cells, that include two conserved T cell subsets expressing invariant antigen-specific receptors, the CD1d-restricted natural killer T cells which are activated by glycolipids, and the mucosal-associated invariant T cells which play a role in defense against orally acquired pathogens in the intestinal mucosa, have only begun to receive attention. A greater knowledge of the range of T cell responses induced by H. pylori is required for a deeper understanding of the pathogenesis of this bacterium and its ability to perpetuate chronic infection, and could reveal new strategies for therapeutic exploitation.

Cancer determining information transmission and circulation

Cancer determining information transmission, typically oncogene transfer, is known in many cases of virus initiated tumors. Transmission of carcinogenic information, that stored in plasmids named T-DNAs, is also known to take place in one type of bacteria induced tumor, that caused by Agrobacterium tumefaciens in dicotyledon plants roots. Other mechanisms of carcinogenic information transmission have been more recently recognized, that involve horizontal transfer of genetic material among cells. Despite this latter issue is not new, insights in its mechanisms have just beginning to appear in the literature. Horizontal transfer processes, in addition to the well known vertical transfer from parental to daughter cancer cells, have been tentatively put together with a reductionistic approach in this work, leading to a unifying framework that summarizes the state of the art in carcinogenic information transmission and circulation in the world of cells. Counteracting vectors of carcinogenic information transmission and circulation, such as oncoviruses, has already been shown to be important both in the fields of cancer prevention and therapy. Investigating today unexplored ways of transmission could lead to implement new anticancer strategies.

H pylori are associated with chronic cholecystitis

AIM: To study whether H pylori are associated with chronic cholecystitis.

METHODS: The subjects were divided into three groups: H pylori-infected cholecystitis group, H pylori-negative cholecystitis group and control group. Pathologic changes of the gallbladder were observed by optic and electronic microscopes and the levels of interleukin-1, 6 and 8 (IL-1, 6 and 8) were detected by radioimmunoassay.

RESULTS: Histological evidence of chronic cholecystitis including degeneration, necrosis, inflammatory cell infiltration, were found in the region where H pylori colonized. Levels of IL-1, 6 and 8 in gallbladder mucosa homogenates were significantly higher in H pylori-infected cholecystitis group than those in H pylori-negative cholecystitis group and control group.

CONCLUSION: H pylori infection may be related to cholecystitis.

A Case of Cutaneous T Cell Pseudolymphoma in a Patient with Helicobacter pylori Infection

Cutaneous pseudolymphomas (CPL) are benign cutaneous lymphoproliferative infiltrations of various origin, including among others bacterial infections, viral infections and drugs . Helicobacter pylori has been frequently founded in the stomach of patients with MALT lymphoma. In January 2001, a 43-year-old man was referred to our department because of a 1-month history of itchy erythematous patches, plaques and flat tumors on his body. Histological examination revealed nodular infiltrations composed of lymphocytes, plasma cells and histiocytes with exocytosis of lymphocytes within the epidermis. Molecular analysis of rearrangement of T cell receptor and immunoglobulin heavy-chain genes did not reveal monoclonality. Based on these clinical, laboratory and histopathological data, a diagnosis of cutaneous T cell pseudolymphoma (CTPL) was made. The patient was anti-H. pylori antibody-positive, and was treated with anti-H. pylori combination with the result that all of the tumors had disappeared by January 2002. The patient has maintained complete response up to the last follow-up visit in December 2005.

Ulkuskrankheit

Treatment of peptic ulcer disease has undergone a radical change due to the discovery of its main cause, the Helicobacter pylori infection. The management of the chronic infection is now the primary aim. Treatment of peptic ulcer essentially consists of eradicating H. pylori. A current problem is the resistance developed by H. pylori to the antibiotics used in eradication regimen. Ulcers that are induced by nonsteroidal antirheumatic (NSAR) agents and acetylsalicylic acid are gaining in importance. Optimized inhibition of acid secretion with proton pump inhibitors has made it possible to both prevent and cure ulcers in the stomach and duodenum caused by NSAR agents.

Mycosis fungoides: is it a Borrelia burgdorferi-associated disease?

Mycosis fungoides (MF) is the most frequently found cutaneous T-cell lymphoma with an unknown aetiology. Several aetiopathogenetic mechanisms have been postulated, including persistent viral or bacterial infections. We looked for evidence of Borrelia burgdorferi (Bb), the aetiologic agent of Lyme disease (LD), in a case study of MF patients from Northeastern Italy, an area with endemic LD. Polymerase chain reaction for the flagellin gene of Bb was used to study formalin-fixed paraffin-embedded lesional skin biopsies from 83 patients with MF and 83 sex- and age-matched healthy controls with homolocalised cutaneous nevi. Borrelia burgdorferi-specific sequence was detected in 15 out of 83 skin samples of patients with MF (18.1%), but in none out of 83 matched healthy controls (P<0.0001). The Bb positivity rates detected in this study support a possible role for Bb in the aetiopathogenesis of MF in a population endemic for LD.

Duodenal intraepithelial lymphocytosis with normal villous architecture: common occurrence in H. pylori gastritis

We have observed expansions of intraepithelial lymphocytes in duodenal biopsies from patients with Helicobacter pylori gastritis. This study was undertaken to prospectively evaluate, unselected, paired gastric and duodenal biopsies from 50 patients with H. pylori gastritis and a comparison group of 30 patients with other types of gastritis (10 autoimmune and 20 reactive) to: (1) quantify duodenal intraepithelial lymphocytes, determine their distribution patterns, epithelial location, and phenotype, and (2) correlate the intraepithelial lymphocyte elevations with various features of gastric and duodenal pathology. Intraepithelial lymphocytes were analyzed with antibodies including CD3, CD8, and TIA-1. A stain for H. pylori was performed on all gastric and duodenal biopsies. Duodenal intraepithelial lymphocytes from patients with H. pylori gastritis (using CD3) ranged from 3 to 42 lymphocytes/100 epithelial cells (mean 18.5) compared to 3 to 18 lymphocytes/100 epithelial cells (mean 6.6) in the comparison group. Intraepithelial lymphocyte elevations were seen in 44% of the duodenal biopsies from patients with H. pylori gastritis (using CD3). Significant differences in the intraepithelial lymphocyte counts between patients with H. pylori gastritis and the comparison group were seen for all three T-cell antigens (P<0.001 for CD3 and CD8 and P<0.002 for TIA-1). Duodenal intraepithelial lymphocytes in the H. pylori+ cases had a latent cytotoxic phenotype, H. pylori was not visualized in any of the duodenal biopsies from patients with H. pylori gastritis, and no patient had clinical evidence of celiac disease. Our study highlights frequent duodenal intraepithelial lymphocytosis in individuals with H. pylori gastritis and the lymphocyte distribution patterns (and numbers) overlapped with those described for celiac disease patients. H. pylori gastritis must be considered as a possible explanation for duodenal intraepithelial lymphocytosis with normal villous architecture, especially when lymphocytosis is patchy, intraepithelial lymphocytes display a 'latent' cytotoxic phenotype, and the clinical findings and serologic profile does not fit celiac disease.

Natural history of gastric mucosal cytokine expression in Helicobacter pylori gastritis in Mongolian gerbils

Data regarding the chronological changes in gastric mucosal cytokines in the different phases of Helicobacter pylori infection are unavailable. We examined Mongolian gerbils for up to 52 weeks after H. pylori (ATCC 43504) inoculation. Levels of mRNAs of mucosal cytokines (interleukin-1beta [IL-1beta], gamma interferon [IFN-gamma], IL-4, IL-6, and IL-10) were assessed using real-time reverse transcription-PCR. Starting 26 weeks after H. pylori inoculation, two clinicohistologic patterns appeared: gastric ulcers in 32% and hyperplastic polyps in 68% of gerbils. High levels of mucosal IL-1beta mRNA were observed early in the infection, reaching maximum at 4 weeks and then rapidly declining. Mucosal IFN-gamma mRNA also reached maximal levels at 4 weeks but remained high thereafter. Both IL-1beta and IFN-gamma mRNA levels were consistently higher in the pyloric mucosa than in the fundic mucosa. In contrast, IL-4, IL-6, and IL-10 mRNA levels peaked at 8 to 26 weeks and levels were similar in the pyloric mucosa and the fundic mucosa. IFN-gamma mRNA levels were significantly higher in gerbils with ulcers than in those with hyperplastic polyps (median IFN-gamma/glyceraldehyde-3-phosphate dehydrogenase ratio x 100,000 = 650 versus 338, respectively [antrum], and 172 versus 40, respectively [corpus]) (P < 0.05). We propose that the different outcomes (e.g., ulcers or hyperplastic polyps) might relate to imbalances among cytokines.

Increased Frequency of Antral CD4+ T and CD19+ B Cells in Patients with Helicobacter pylori-Related Peptic Ulcer Disease

Only a fraction of Helicobacter pylori (HP)-infected individuals develop clinical disease. Recent research indicates that immunological mechanisms may be important for understanding the pathophysiology of HP infection. Differences in the individual cellular immune response may reflect the clinical diversity. The aim of the present study was to investigate the cellular immune response against HP in three clinically well-defined patient groups: HP-positive peptic ulcer, HP-positive and HP-negative gastritis. Biopsies from gastric mucosa were processed for analysis by flow cytometry and histology. The number of T lymphocytes (CD3+) was significantly higher in HP-positive peptic ulcer (13.8%) than in HP-positive nonulcer gastritis (6.3%). A nonsignificant increase for B lymphocytes (CD19+) was noted as well. Furthermore, a significant difference was seen in mucosal CD4/CD8 ratio between HP ulcer (2.4) and nonulcer HP gastritis (1.0) patients. Thus, B cells (CD19+) and T-helper cells (CD4+) were dominant in gastric mucosa from peptic ulcer patients, and cytotoxic T cells (CD8+) were relatively dominant in gastric mucosa from nonulcer patients. In conclusion, distinct differences in the T-cell subset distribution of mucosal lymphocytes were detected in patients with HP infection, strongly correlated with the presence or absence of peptic ulcer.

Relationship between Helicobacter pylori and chronic cholecystitis

AIM: To study whether Helicobacter pylori (H. pylori) is associated with chronic cholecystitis.

METHODS: Chronic cholecystitis specimens confirmed by pathological analysis were divided into three groups: H. pylori infected group, H. pylori negative group and control group. The pathologic changes of cholecystitis were observed with light and electron microscopy, and the levels of interleukins (IL-1, IL-6 and IL-8) were also detected by radioimmunoassy.

RESULTS: Histological evidences of chronic choleystitis were found in the region where H. pylori colonized, including degeneration, necrosis, inflammatory cell infiltration, etc. Levels of interleukins (IL-1, 6, 8) in gallbladder homogenate were significantly higher in H. pylori-infected cholecystitis group than those in H. pylori -negative cholecystitis group and control group.

CONCLUSION: H. pylori virulence factor and interleukins may be involved in the pathogenesis of H. pylori -related cholecystitis.

Helicobacter pylori infection negatively influences pregnancy outcome in a mouse model

BACKGROUND

Helicobacter pylori infects the human stomach, causing gastritis, peptic ulcer, and gastric cancer. H. pylori infection has also been related to extra-gastric disorders. We investigated whether H. pylori infection can influence pregnancy in a murine model.

METHODS

Female CD1 mice were infected with the H. pylori SPM326 strain before mating, and then assessed throughout pregnancy for embryo/fetus characteristics and histopathological changes of the endometrium.

RESULTS

Infected mice showed higher numbers of resorption and lower fetal weights than noninfected controls. These pathological phenomena were accompanied by macrophage activation, and increases both of CD4+ and CD8+ lymphocytes and of interferon-gamma and major histocompatibility complex class II expression at the endometrial level, as evaluated by immunohistochemistry.

DISCUSSION

During pregnancy, preferential induction of Th2-type cytokines downregulates Th1-type responses, allowing fetal survival. Our results suggest that H. pylori infection can induce activation of resident uterine immune cells and/or recruitment of cells at the endometrial level. It can be hypothesized that the local Th1-type response induced by H. pylori infection could alter the systemic Th1/Th2-type cytokine balance at sites under particular physiopathological conditions of active tissue and/or vascular formation, such as pregnancy.

CONCLUSIONS

This is the first evidence in an animal model of the possible influence of H. pylori infection on pregnancy. Further work is required on its mechanism and its relevance for humans.

IgG subclass response to Helicobacter pylori and CagA antigens in children

Specific serum IgG subclass antibodies against Helicobacter pylori antigens and recombinant CagA were analysed in 75 symptomatic children with histologically confirmed H. pylori infection. H. pylori stimulated an IgG1 predominant response, and IgG3 titres showed a positive association with peptic ulcer disease, chronicity of antral inflammation and density of H. pylori colonization. Two methods used for assessing serum IgG CagA antibody status, i.e. Western blotting and enzyme-linked immunosorbent assay (ELISA), were concordant. CagA stimulated an IgG1 and IgG3 predominant humoral response. Total CagA IgG titres were higher in children with active and more severe chronic antral inflammation. These findings suggest that in children the systemic humoral immune response to H. pylori infection may reflect gastroduodenal pathology.