Causality of Helicobacter pylori infection on eosinophilic esophagitis and potential pathogenesis: a Mendelian randomization study.

Background: Observational studies have indicated a possible connection between Helicobacter pylori (H. pylori) infection and eosinophilic esophagitis (EoE), but their causal relationship has yet to be established. To investigate the causal associations between H. pylori infection and EoE, we performed a Mendelian randomization (MR) analysis. Methods: Firstly, we conducted both univariable and multivariable Mendelian randomization (MR) analyses. Furthermore, a two-step MR was carried out to ascertain the potential underlying pathways of these associations, particularly the involvement of inflammatory cytokines. We employed the inverse-variance weighted (IVW) method as the main analysis in our MR study. To enhance the credibility of the results, we also conducted several sensitivity analyses. Results: Our study demonstrated a noteworthy correlation between genetically predicted anti-H. pylori IgG antibody levels and a reduced risk of EoE (OR=0.325, 95% CI=0.165-0.643, P value=0.004, adj p value=0.009). No significant causal associations were detected between other H. pylori antibodies and EoE in our study. When it comes to multivariable MR analysis controlling for education attainment, household income, and deprivation individually, the independent causal impact of anti-H. pylori IgG on EoE persisted. Surprisingly, the two-step MR analysis indicated that inflammatory factors (IL-4, IL-5, IL-13, IL-17, and IFN-γ) did not appear to mediate the protective effect of H. pylori infection against EoE. Conclusion: Findings suggested that among the range of H. pylori-related antibodies, anti-H. pylori IgG antibody is the sole causal factor associated with protection against EoE. Certain inflammatory factors may not be involved in mediating this association. These findings make a significant contribution to advancing our understanding of the pathogenesis of EoE and its evolving etiology.

Detection of Helicobacter pylori strain types and analysis of risk factors among subjects from Hainan Province, China.

OBJECTIVE: To explore the prevalence of type I and type II Helicobacter pylori infection and investigate risk factors in a population from Hainan Province in China. METHODS: Data came from a large, cross-sectional study conducted from August 2022 to April 2023 involving five cities of Hainan. Subjects with confirmed 14C-urea breath test (UBT) and positive serological assay were included. All subjects had a gastroscopy. According to presence or absence of CagA/VacA proteins, subjects were classified as either type I (present) or type II strains (absent). Gastroscopic findings and several socio-demographic factors were examined for correlation with antibody serotyping. RESULTS: In total, 410 subjects were investigated for H. pylori strain types. The overall prevalence of the highly virulent, type I H. pylori strain was 79% (324/410) and type II strain was 21% (86/410). There was a strong association between type I strain and peptic ulcer disease. Of several sociodemographic factors investigated, only smoking and data over baseline (DOB) values showed significant differences between type 1 and type II strains. Logistic regression analysis showed a lower risk of type I H. pylori infection in smokers compared with non-smokers, and a higher risk of H. pylori type I infection in subjects with medium and high data over baseline (DOB) values compared with subjects who had low DOB values. CONCLUSION: Highly virulent, type I H. pylori infections predominate in Hainan and the co-positivity of CagA and VacA antibodies are related to type I H. pylori infection. We found that Type I H. pylori was closely associated with peptic ulcer disease and the DOB values were generally high.

M2 macrophages participate in ILC2 activation induced by Helicobacter pylori infection.

Helicobacter pylori (H. pylori) causes a diversity of gastric diseases. The host immune response evoked by H. pylori infection is complicated and can influence the development and progression of diseases. We have reported that the Group 2 innate lymphocytes (ILC2) were promoted and took part in building type-2 immunity in H. pylori infection-related gastric diseases. Therefore, in the present study, we aim to clarify how H. pylori infection induces the activation of ILC2. It was found that macrophages were necessary for activating ILC2 in H. pylori infection. Mechanistically, H. pylori infection up-regulated the expression of indoleamine 2,3-dioxygenase (IDO) in macrophages to induce M2 polarization, and the latter secreted the alarmin cytokine Thymic Stromal Lymphopoietin (TSLP) to arouse ILC2.

Nationwide survey of Helicobacter pylori seropositivity and gastric atrophy in Zambia.

BACKGROUND: Helicobacter pylori (H. pylori) is a common bacterial infection which predominately drives upper gastrointestinal pathology. We carried out a nationwide serological survey in response to the deficiency of robust African data on H. pylori prevalence, age of acquisition, socio-geographic determinants, and impact on gastric physiology. MATERIALS AND METHODS: This was a cross-sectional study of archival plasma samples collected during the Zambia Population-based HIV impact Assessment (ZAMPHIA) 2016 survey. ZAMPHIA used a two-stage door-to-door stratified cluster sample approach to collect samples from adults and children from age 0 to 59 years (n = 24,266). We randomly retrieved one fifth of these samples from each of Zambia's 10 provinces and used ELISA to test for H. pylori IgG antibodies, pepsinogen 1 and 2 and gastrin-17. A pepsinogen 1:2 ratio of <3 was used to define gastric atrophy. RESULTS: The analysis of 4050 plasma samples (30% <16 years, 53% females) revealed an overall H. pylori seroprevalence of 79%. By the age of 10 years, more than 75% of the children had H. pylori. Urban residence was associated with increased odds (OR 1.8, 95% CI 1.5-2.2, p < 0.001) and HIV infection was associated with reduced odds (OR 0.7, 95% CI 0.5-0.9, p = 0.02) of H. pylori seropositivity. Gastric atrophy was detected in 6% of H. pylori seropositive adults below 45 years of age and 9% in those between 45 and 59 years. CONCLUSIONS: We have confirmed a high prevalence of H. pylori seropositivity in Zambia, predominantly in urban settings. The prevalence of gastric atrophy is broadly consistent with other populations around the globe, but our sample did not include adults over 60 years.

Fatty acids of Helicobacter pylori lipoproteins CagT and Lpp20.

Bacterial lipoproteins are post-translationally modified by the addition of acyl chains that anchor the protein to bacterial membranes. This modification includes two ester-linked and one amide-linked acyl chain on lipoproteins from Gram-negative bacteria. Helicobacter pylori lipoproteins have important functions in pathogenesis (including delivering the CagA oncoprotein to mammalian cells) and are recognized by host innate and adaptive immune systems. The number and variety of acyl chains on lipoproteins impact the innate immune response through Toll-like receptor 2. The acyl chains added to lipoproteins are derived from membrane phospholipids. H. pylori membrane phospholipids have previously been shown to consist primarily of C14:0 and C19:0 cyclopropane-containing acyl chains. However, the acyl composition of H. pylori lipoproteins has not been determined. In this study, we characterized the acyl composition of two representative H. pylori lipoproteins, Lpp20 and CagT. Fatty acid methyl esters were prepared from both purified lipoproteins and analyzed by gas chromatography-mass spectrometry. For comparison, we also analyzed H. pylori phospholipids. Consistent with previous studies, we observed that the H. pylori phospholipids contain primarily C14:0 and C19:0 cyclopropane-containing fatty acids. In contrast, both the ester-linked and amide-linked fatty acids found in H. pylori lipoproteins were observed to be almost exclusively C16:0 and C18:0. A discrepancy between the acyl composition of membrane phospholipids and lipoproteins as reported here for H. pylori has been previously reported in other bacteria including Borrelia and Brucella. We discuss possible mechanisms.IMPORTANCEColonization of the stomach by Helicobacter pylori is an important risk factor in the development of gastric cancer, the third leading cause of cancer-related death worldwide. H. pylori persists in the stomach despite an immune response against the bacteria. Recognition of lipoproteins by TLR2 contributes to the innate immune response to H. pylori. However, the role of H. pylori lipoproteins in bacterial persistence is poorly understood. As the host response to lipoproteins depends on the acyl chain content, defining the acyl composition of H. pylori lipoproteins is an important step in characterizing how lipoproteins contribute to persistence.

Association of Helicobacter pylori CagA seropositivity with gastric precancerous lesions: a systematic review and meta-analysis.

The objective of this meta-analysis is to delineate the association between H. pylori CagA serological status and the prevalence of gastric precancerous lesions (GPL). We searched peer-reviewed articles up to October 2023. The extraction of data from the included studies was carried out as well as the quality assessment. Pooled effect sizes were calculated using a random effect model. Thirteen studies met the inclusion criteria, comprising 2728 patients with GPL and 17 612 controls. The aggregate odds ratio (OR) for the association between serum CagA and GPL was 2.74 (95% CI = 2.25-3.32; P  = 0.00; I 2  = 60.4%), irrespective of H. pylori infection status. Within the H. pylori -infected cohort, the OR was 2.25 (95% CI = 1.99-2.56; P  = 0.00; I 2  = 0.0%). Conversely, among the non-infected individuals, the OR was 1.63 (95% CI = 1.04-2.54; P  = 0.038; I 2  = 0.0%). Heterogeneity was explored using subgroup and meta-regression analyses, indicating that the variability between studies likely stemmed from differences in disease classification. Our results demonstrated robustness and negligible publication bias. The meta-analysis underscores a more pronounced association between H. pylori CagA seropositivity and the risk of developing GPL than between seronegativity and the same risk, irrespective of H. pylori infection status at the time. Additionally, the strength of the association was heightened in the presence of an active H. pylori infection. The implications of these findings advocate for the utility of CagA serostatus as a potential biomarker for screening GPL.

Helicobacter pylori secretary Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation.

Helicobacter pylori-associated stomach infection is a leading cause of gastric ulcer and related cancer. H. pylori modulates the functions of infiltrated immune cells to survive the killing by reactive oxygen and nitrogen species (ROS and RNS) produced by these cells. Uncontrolled immune responses further produce excess ROS and RNS which lead to mucosal damage. The persistent oxidative stress is a major cause of gastric cancer. H. pylori regulates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), nitric oxide synthase 2 (NOS2), and polyamines to control ROS and RNS release through lesser-known mechanisms. ROS and RNS produced by these pathways differentiate macrophages and T cells from protective to inflammatory phenotype. Pathogens-associated molecular patterns (PAMPs) induced ROS activates nuclear oligomerization domain (NOD), leucine rich repeats (LRR) and pyrin domain-containing protein 3 (NLRP3) inflammasome for the release of pro-inflammatory cytokines. This study evaluates the role of H. pylori secreted concentrated proteins (HPSCP) related oxidative stress role in NLRP3 inflammasome activation and macrophage differentiation. To perceive the role of ROS/RNS, THP-1 and AGS cells were treated with 10 µM diphenyleneiodonium (DPI), 50 µM salicyl hydroxamic acid (SHX), 5 µM Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP), which are specific inhibitors of NADPH oxidase (NOX), Myeloperoxidase (MPO), and mitochondrial oxidative phosphorylation respectively. Cells were also treated with 10 µM of NOS2 inhibitor l-NMMA and 10 µM of N-acetyl cysteine (NAC), a free radical scavenger·H2O2 (100 µM) treated and untreated cells were used as positive controls and negative control respectively. The expression of gp91phox (NOX2), NOS2, NLRP3, CD86 and CD163 was analyzed through fluorescent microscopy. THP-1 macrophages growth was unaffected whereas the gastric epithelial AGS cells proliferated in response to higher concentration of HPSCP. ROS and myeloperoxidase (MPO) level increased in THP-1 cells and nitric oxide (NO) and lipid peroxidation significantly decreased in AGS cells. gp91phox expression was unchanged, whereas NOS2 and NLRP3 downregulated in response to HPSCP, but increased after inhibition of NO, ROS and MPO in THP-1 cells. HPSCP upregulated the expression of M1 and M2 macrophage markers, CD86 and CD163 respectively, which was decreased after the inhibition of ROS. This study concludes that there are multiple pathways which are generating ROS during H. pylori infection which further regulates other cellular processes. NO is closely associated with MPO and inhibition of NLRP3 inflammasome. The low levels of NO and MPO regulates gastrointestinal tract homeostasis and overcomes the inflammatory response of NLRP3. The ROS also plays crucial role in macrophage polarization hence alter the immune responses duing H. pylori pathogenesis.

Proteolytic Landscapes in Gastric Pathology and Cancerogenesis.

Gastric cancer is a leading cause of cancer-related death, and a large proportion of cases are inseparably linked to infections with the bacterial pathogen and type I carcinogen Helicobacter pylori. The development of gastric cancer follows a cascade of transformative tissue events in an inflammatory environment. Proteases of host origin as well as H. pylori-derived proteases contribute to disease progression at every stage, from chronic gastritis to gastric cancer. In the present article, we discuss the importance of (metallo-)proteases in colonization, epithelial inflammation, and barrier disruption in tissue transformation, deregulation of cell proliferation and cell death, as well as tumor metastasis and neoangiogenesis. Proteases of the matrix metalloproteinase (MMP) and a disintegrin and metalloproteinase domain-containing protein (ADAM) families, caspases, calpain, and the H. pylori proteases HtrA, Hp1012, and Hp0169 cleave substrates including extracellular matrix molecules, chemokines, and cytokines, as well as their cognate receptors, and thus shape the pathogenic microenvironment. This review aims to summarize the current understanding of how proteases contribute to disease progression in the gastric compartment.

Hygiene Hypothesis Indicators and Prevalence of Antinuclear Antibodies in US Adolescents.

Autoimmunity prevalence, as measured by antinuclear antibodies (ANA), is increasing in U.S. adolescents. Improved hygiene and cleaner environments in childhood may reduce exposure to infections and other immune challenges, resulting in improper immune responses to later-life exposures. We examined associations of hygiene hypothesis indicators, including asthma, allergies, and antibodies to infectious agents, with ANA prevalence, measured by HEp-2 immunofluorescence, in adolescents (aged 12-19 years) over a 25-year time span in the National Health and Nutrition Examination Survey (NHANES) (N=2,709), adjusting for age, sex, race/ethnicity, body mass index, education and survey cycle, overall and within individual time periods, using logistic regression. Prevalence of ANA in adolescents increased from 5.0% in 1988-1991 to 12.8% in 2011-2012. ANA were positively associated with diagnosis of asthma in early childhood (OR: 2.07, CI: 1.09-3.99) and the effect estimate for current hay fever was elevated but not statistically significant (OR: 1.55, CI: 0.85-2.84). Fewer than 2% of those with ANA in 1988-1991 had been diagnosed with asthma, compared with 18% in 1999-2000, and 27% in 2003-2004 and 2011-2012. ANA trended negatively with Helicobacter pylori antibodies (OR: 0.49, CI: 0.24-0.99). ANA may be useful as an additional indicator of inadequate immune education in adolescence, a critical period of growth and development.

Investigation of the quantitative detection of serum Helicobacter pylori antibody in clinical laboratories in China.

BACKGROUND: This study aimed to investigate the implementation and quality control of the quantitative detection of serum Helicobacter pylori (H. pylori) antibody in clinical laboratories in China. METHODS: Online external quality assessment (EQA) questionnaires were distributed to the clinical laboratories by National Center for Clinical Laboratories (NCCL) of China. We collected information on the quantitative detection procedures of serum H. pylori antibody in clinical laboratories, including detection reagents, methods, instruments, calibrators, and internal quality control (IQC). We distributed quality control products to some select laboratories that conducted quantitative detection and analyzed the obtained test data. We evaluated the quantitative detection procedure based on the standard evaluation criteria set at a target value of ±30%. RESULTS: 70.9% (146/206) of the laboratories conducted quantitative detection of H. pylori antibody; 29.1% (60/206) of the laboratories performed qualitative detection. Domestic reagents and matching calibrators accounted for more than 97.1% (200/206) of all reagents. Latex-enhanced immunoturbidimetry was used in 89.7% (131/146) of the laboratories for quantitative determination, while the colloidal gold method was used in 66.7% (40/60) of the laboratories for qualitative determination. A total of 130 laboratories participated in the EQA; 123 completed the assessment, and the pass rate was 75.6% (93/123). CONCLUSION: Clinical quantitative detection of serum H. pylori antibody is performed at a high rate in China. Thus, further studies on the specificity of commercial detection reagents are needed. EQAs are useful to monitor and improve the detection quality of H. pylori antibodies.

HomA and HomB, outer membrane proteins of Helicobacter pylori down-regulate activation-induced cytidine deaminase (AID) and Ig switch germline transcription and thereby affect class switch recombination (CSR) of Ig genes in human B-cells.

H. pylori is one of the major causes of chronic gastritis, peptic ulcer disease (PUD), gastric mucosa-associated lymphoid tissue lymphoma (MALT) and gastric carcinoma. H. pylori toxin VacA is responsible for host cell apoptosis, whereas CagA is known to aberrantly induce expression of activation-induced cytidine deaminase (AID) in gastric epithelial cells that causes mutations in oncogenes and tumour suppressor genes, leading to the transformation of normal cells into cancerous cells. Although, a significant amount of research has been conducted to understand the role of bacterial factors modulating deregulated host cell pathways, the interaction between H. pylori and immune cells of the marginal zone and its consequences are still not well understood. HomB and HomA, outer membrane proteins (OMPs) from H. pylori, which assist in the adhesion of bacteria to host cells, are found to be associated with H. pylori virulent strains and promote inflammation. Interestingly, we observed that the interaction of HomB/HomA OMPs with B-cells transiently downregulates AID expression and Ig switch germline transcription. Downregulation of AID leads to impairment of class switch recombination (CSR), resulting in significantly reduced switching to IgG and IgA antibodies. Besides, we examined the immune-suppressive response of B-cells and observed that the cells stimulated with HomA/B show upregulation in the levels of IL10, IL35, as well as PDL1, a T-cell inhibition marker. Our study suggests the potential role of OMPs in immune response modulation strategies used by the pathogen to evade the immune response. These results provide a better understanding of H. pylori pathogenesis and assist in identifying novel targets for therapy.

Caulerpin Mitigates Helicobacter pylori-Induced Inflammation via Formyl Peptide Receptors.

The identification of novel strategies to control Helicobacter pylori (Hp)-associated chronic inflammation is, at present, a considerable challenge. Here, we attempt to combat this issue by modulating the innate immune response, targeting formyl peptide receptors (FPRs), G-protein coupled receptors that play key roles in both the regulation and the resolution of the innate inflammatory response. Specifically, we investigated, in vitro, whether Caulerpin-a bis-indole alkaloid isolated from algae of the genus Caulerpa-could act as a molecular antagonist scaffold of FPRs. We showed that Caulerpin significantly reduces the immune response against Hp culture filtrate, by reverting the FPR2-related signaling cascade and thus counteracting the inflammatory reaction triggered by Hp peptide Hp(2-20). Our study suggests Caulerpin to be a promising therapeutic or adjuvant agent for the attenuation of inflammation triggered by Hp infection, as well as its related adverse clinical outcomes.

Helicobacter pylori-induced REDD1 modulates Th17 cell responses that contribute to gastritis.

OBJECTIVE: Regulated in development and DNA damage responses-1 (REDD1) is a conserved and ubiquitous protein, which is induced in response to multiple stimuli. However, the regulation, function and clinical relevance of REDD1 in Helicobacter pylori-associated gastritis are presently unknown. APPROACH: Immunohistochemistry, real-time PCR and Western blot analyses were performed to examine the levels of REDD1 in gastric samples from H. pylori-infected patients and mice. Gastric tissues from Redd1-/- and wildtype (WT, control) mice were examined for inflammation. Gastric epithelial cells (GECs), monocytes and T cells were isolated, stimulated and/or cultured for REDD1 regulation and functional assays. RESULTS: REDD1 was increased in gastric mucosa of H. pylori-infected patients and mice. H. pylori induced GECs to express REDD1 via the phosphorylated cytotoxin associated gene A (cagA) that activated MAPKp38 pathway to mediate NF-κB directly binding to REDD1 promoter. Human gastric REDD1 increased with the severity of gastritis, and mouse REDD1 from non-marrow chimera-derived cells promoted gastric inflammation that was characterized by the influx of MHCII+ monocytes. Importantly, gastric inflammation, MHCII+ monocyte infiltration, IL-23 and IL-17A were attenuated in Redd1-/- mice. Mechanistically, REDD1 in GECs regulated CXCL1 production, which attracted MHCII+ monocytes migration by CXCL1-CXCR2 axis. Then H. pylori induced MHCII+ monocytes to secrete IL-23, which favored IL-17A-producing CD4+ cell (Th17 cell) polarization, thereby contributing to the development of H. pylori-associated gastritis. CONCLUSIONS: The present study identifies a novel regulatory network involving REDD1, which collectively exert a pro-inflammatory effect within gastric microenvironment. Efforts to inhibit this REDD1-dependent pathway may prove valuable strategies in treating of H. pylori-associated gastritis.

Serological Biomarker Panel in Diagnosis of Atrophic Gastritis and Helicobacter pylori Infection in Gastroscopy Referral Patients: Clinical Validation of the New-Generation GastroPanel® Test.

BACKGROUND/AIM: Prompted by the increasing demand of non-invasive diagnostic tools for screening of gastric cancer (GC) risk conditions, i.e., atrophic gastritis (AG) and Helicobacter pylori (Hp) infection, the GastroPanel® test (GP: biomarker panel of PGI, PGII, G-17, Hp IgG ELISA) that was developed in the early 2000's, was recently updated to a new-generation (unified GP) test version. This clinical validation study evaluated the diagnostic accuracy of the new-generation GP test in detection of AG and Hp among gastroscopy referral patients in a University Clinic. PATIENTS AND METHODS: Altogether, 522 patients were enrolled among the patients referred for gastroscopy at the Gastro Center, Oulu University Hospital (OUH). All patients underwent gastroscopy with biopsies classified using the Updated Sydney System (USS), and blood sampling for GP testing. RESULTS: Biopsy-confirmed AG was found in 10.2% (53/511) of the patients. The overall agreement between the GP and the USS classification was 92.4% (95%CI=90.0-94.6%), with the weighted kappa (κw) of 0.861 (95%CI=0.834-0.883). In ROC analysis using moderate/severe AG of the corpus (AGC2+) as the endpoint, AUC=0.952 (95%CI=0.891-1.000) and AUC=0.998 (95%CI=0.996-1.000) for PGI and PGI/PGII, respectively. Hp IgG antibody ELISA detected biopsy-confirmed Hp-infection with AUC=0.993 (95%CI=0.987-0.999). CONCLUSION: The new generation GastroPanel® is a precise test for non-invasive diagnosis of atrophic gastritis and Hp-infection in dyspeptic patients referred for diagnostic gastroscopy.

Cytotoxin-associated gene A (CagA) promotes aortic endothelial inflammation and accelerates atherosclerosis through the NLRP3/caspase-1/IL-1ß axis.

Atherosclerosis is a chronic inflammatory disease. Pathophysiological similarities between chronic infections and atherosclerosis triggered interests between these conditions. The seroepidemiological study showed that Helicobacter pylori strains that express cytotoxin-associated gene A (CagA), an oncoprotein and a major virulence factor, was positively correlated with atherosclerosis and related clinical events. Nevertheless, the underlying mechanism is poorly understood. In this study, the seroprevalence of infection by H. pylori and by strains express CagA assessed by enzyme-linked immunosorbent assay (ELISA) showed that the prevalence of CagA strains rather than H. pylori in patients was positively correlated with atherogenesis. Correspondingly, we found that CagA augmented the growth of plaque of ApoE-/- mice in the early stage of atherosclerosis and promoted the expression of adhesion molecules and inflammatory cytokines in mouse aortic endothelial cells (MAECs). Mechanistically, both si-NLRP3 and si-IL-1ß mitigated the promoting effect of CagA on the inflammatory activation of HAECs. In vivo, the inhibition of NLRP3 by MCC950 significantly attenuated the promoting effect of CagA on plaque growth of ApoE-/- mice. We also propose NLRP3 as a potential therapeutic target for CagA-positive H. pylori infection-related atherosclerosis and emphasize the importance of inflammation in atherosclerosis pathology.

GITR Promotes the Polarization of TFH-Like Cells in Helicobacter pylori-Positive Gastritis.

Gastric CD4+T cells contribute to Helicobacter pylori (H. pylori)-induced gastritis by amplifying mucosal inflammation and exacerbating mucosal injuries. However, the pathogenic CD4+ T cell subset involved in gastritis and the potential regulators are still unclear. Here we identified an IL-21-producing gastric CD4+T cell subset, which exhibited tissue-resident CXCR5-BTLA-PD-1hi TFH-like phenotype in H. pylori-positive gastritis patients. Meanwhile, we identified glucocorticoid-induced tumor necrosis factor receptor (GITR) as an important regulator to facilitate IL-21 production by CD4+T cells and accelerate mucosal inflammation in gastritis patients with H. pylori infection. Moreover, GITR expression was increased in gastric CD4+T cells of gastritis patients compared to healthy controls, along with the upregulated expression of its ligand GITRL in mucosal macrophages (Mϕ) of gastritis patients. Further observations showed that the activation of GITR/GITRL signal promoted the IL-21 production of CD4+T cells via the STAT3 pathway. Besides this, IL-21 from CD4+T cells induced the proliferation of B cell and promoted the production of inflammatory cytokines IL-1ß and IL-6 and chemokines MIP-3α and CCL-25 as well as matrix metalloproteinase (MMP)-3 and MMP-9 by human gastric epithelial cells, suggesting the facilitating effect of IL-21-producing CD4+T cells on mucosal inflammation and injuries. Taking these data together, we revealed that GITR/GITRL signal promoted the polarization of mucosal IL-21-producing CD4+T cells in H. pylori-positive gastritis, which may provide therapeutic strategies for the clinical treatment of H. pylori-induced gastritis.

Eosinophils and Bacteria, the Beginning of a Story.

Eosinophils are granulocytes primarily associated with TH2 responses to parasites or immune hyper-reactive states, such as asthma, allergies, or eosinophilic esophagitis. However, it does not make sense from an evolutionary standpoint to maintain a cell type that is only specific for parasitic infections and that otherwise is somehow harmful to the host. In recent years, there has been a shift in the perception of these cells. Eosinophils have recently been recognized as regulators of immune homeostasis and suppressors of over-reactive pro-inflammatory responses by secreting specific molecules that dampen the immune response. Their role during parasitic infections has been well investigated, and their versatility during immune responses to helminths includes antigen presentation as well as modulation of T cell responses. Although it is known that eosinophils can present antigens during viral infections, there are still many mechanistic aspects of the involvement of eosinophils during viral infections that remain to be elucidated. However, are eosinophils able to respond to bacterial infections? Recent literature indicates that Helicobacter pylori triggers TH2 responses mediated by eosinophils; this promotes anti-inflammatory responses that might be involved in the long-term persistent infection caused by this pathogen. Apparently and on the contrary, in the respiratory tract, eosinophils promote TH17 pro-inflammatory responses during Bordetella bronchiseptica infection, and they are, in fact, critical for early clearance of bacteria from the respiratory tract. However, eosinophils are also intertwined with microbiota, and up to now, it is not clear if microbiota regulates eosinophils or vice versa, or how this connection influences immune responses. In this review, we highlight the current knowledge of eosinophils as regulators of pro and anti-inflammatory responses in the context of both infection and naïve conditions. We propose questions and future directions that might open novel research avenues in the future.

Evaluation of an attenuated Listeria monocytogenes as a vaccine vector to control Helicobacter pylori infection.

The increasing resistance of Helicobacter pylori (H. pylori) to antibiotics has limited the efficacy of antibiotic therapy in the treatment of H. pylori-associated gastric diseases. The vaccine as an alternative method is becoming a safe and effective way to address this problem. In previous studies, live vector vaccines have proved to be effective in controlling H. pylori infection. Attenuated Listeria monocytogenes (L. monocytogenes) is a potential candidate vector applied in clinical trials, which can deliver foreign antigens and induce a broad immune response. To further explore the effectiveness of L. monocytogenes as a vaccine vector against H. pylori, attenuated L. monocytogenes-based vaccine EGDeΔactA/inlB(EGDeAB)-MECU was constructed to secrete a multi-epitope chimeric antigen (MECU) containing multiple B cell epitopes from H. pylori antigens. EGDeAB-MECU could secrete MECU stably. After immunized by gavage and intravenous injection, both EGDeAB and EGDeAB-MECU could significantly decrease gastric H. pylori colonization and induce a high level of specific antibodies against H. pylori. In conclusion, attenuated L. monocytogenes had an immunotherapeutic effect on H. pylori-infected mice, indicating its further development as a promising candidate vaccine vector for the H. pylori vaccine.

The crosstalk between H. pylori virulence factors and the PD1:PD-L1 immune checkpoint inhibitors in progression to gastric cancer.

BACKGROUND: The progression to gastric cancer has been linked to chronic infection with Helicobacter pylori (H. pylori). Immune checkpoint inhibitors (programmed cell death -1, PD-1; programmed cell death -ligand 1, PD-L1) have a role in cancer immune escape. The relationship between H. pylori virulence factors with PD-1, PD-L1 T helper 1 (Th1), T helper 17 (Th17), and regulatory T cell (Treg) response genes, has not been thoroughly investigated in the development of gastric cancer. Therefore, we evaluated how H. pylori virulence factors influence the expression levels of immune-related genes in the development of gastric immunopathology. METHODS: A total of 92 gastric tissues of normal controls and patients with gastritis, gastric ulcer, and gastric cancer were examined for the expression of immune-checkpoint inhibitor genes (PD-1 PD-L1), Th1 (interferon- γ, IFN-γ), Th17 (interleukin- 17, IL-17, Retinoic-acid-receptor- related orphan nuclear receptor gamma t, RORγ-t), and Treg (Forkhead box P3, FOXP3) response genes with quantitative real-time PCR (qRT-PCR). Furthermore, correlation of H. pylori virulence factors' (cytotoxin-associated gene A, cagA; vacuolating cytotoxin gene A, vacA (s1,s2,m1,m2); blood group antigen-binding adhesin gene A, babA, duodenal ulcer promoting gene A, dupA; the putative neuraminyllactose-binding hemagglutinin homolog, hpaA; neutrophil-activating protein A napA; outer inflammatory protein A, oipA; urease A, ureA; and urease B, ureB) genotypes with a degree of inflammation and density of H. pylori were investigated. Next, the relationship between H. pylori virulence factors and immune-checkpoint inhibitor genes, and T-cell response genes was evaluated. Eventually, a decision tree model was developed to determine the clinical outcome of patients using expression data. RESULTS: The intensity of PD-1 and PD-L1 mRNA expression was increased significantly in gastric tissue of patients with gastric ulcer (PD-1: 2.3 fold, p=0.01; PD-L1: 2.1 fold, p=0.004), and gastric cancer (PD-1: 2 fold, p= 0.04; PD-L1: 1.8 fold, p=0.05) compared with control subjects. Also, PD-1: PD-L1 expression was significantly higher in patients with gastritis, who were infected with a marked density of H. pylori compared with its mildly infected counterparts. Furthermore, a novel negative correlation was found between PD-1 (r= -0.43) and PD-L1 (r= -0.42) with FOXP3 in patients with gastritis. CagA-positive H. pylori strain's negative association with PD-L1 expression (r=-0.34) was detected in patients with gastritis. Interestingly, PD-1 mRNA expression correlated positively with vacA s2/m2, in gastritis (r=0.43) and ulcer (r=0.43) patients. Furthermore, PD-1: PDL1 expression negatively correlated with vacA m1/m2 (r=-0.43 for PD-1; r=-0.38 for PD-L1) in gastritis patients. Moreover, an inverse correlation of PDL1 was present with vacA m1 (r=0.52) and vacA s1/m1 (r=0.46) versus vacA m2 (r=-0.44) and vacA m1 (r=0.52) and vacA s1/m2 (r=-0.14) in ulcer patients, respectively. Also, a correlation of vacA m2 (r=-0.47) and vacA s1/s2 (r= 0.45) with PD-1 was detected in ulcer patients. In addition, a novel negative correlation between FOXP3 mRNA levels and napA was shown in patients with gastritis and ulcer (r=-0.59). Finally, a computer-based model that was developed showed that knowing the expression levels of PD-L1, RORγ-t, and vacA s1/m2 would be useful to detect the clinical outcome of a patient. CONCLUSION: Our results suggested that PD-1:PD-L1 immune checkpoint inhibitors were increased in gastric pre-cancerous lesions that progress to gastric cancer. Herein, we report the relationship between H. pylori virulence factors and expression of host immune checkpoint inhibitors for diagnostic prediction of gastric malignancies using computer-based models.

Colostrum IgA1 antibodies recognize antigens from Helicobacter pylori and prevent cytoskeletal changesin human epithelial cells.

Helicobacter pylori is a Gram-negative bacterium found on the luminal surface of the gastric mucosa in at least 50% of the world's human population. The protective effect of breastfeeding against H. pylori infection has been extensively reported; however, the mechanisms behind this protection remain poorly understood. Human IgA from colostrum has reactivity against H. pylori antigens. Despite that IgA1 and IgA2 display structural and functional differences, their reactivity against H. pylori had not been previously determined. We attested titers and reactivity of human colostrum-IgA subclasses by ELISA, immunoblot, and flow cytometry. Colostrum samples from healthy mothers had higher titers of IgA; and IgA1 mostly recognized H. pylori antigens. Moreover, we found a correlation between IgA1 reactivity and their neutralizing effect determined by inhibition of cytoskeletal changes in AGS cells infected with H. pylori. In conclusion, colostrum-IgA reduces H. pylori infection of epithelial gastric cells, suggesting an important role in preventing the bacteria establishment during the first months of life. As a whole, these results suggest that IgA1 from human colostrum provides protection that may help in the development of the mucosal immune system of newborn children.