Trained Immunity and Trained Tolerance: The Case of Helicobacter pylori Infection.

Trained immunity is a concept in immunology in which innate immune cells, such as monocytes and macrophages, exhibit enhanced responsiveness and memory-like characteristics following initial contact with a pathogenic stimulus that may promote a more effective immune defense following subsequent contact with the same pathogen. Helicobacter pylori, a bacterium that colonizes the stomach lining, is etiologically associated with various gastrointestinal diseases, including gastritis, peptic ulcer, gastric adenocarcinoma, MALT lymphoma, and extra gastric disorders. It has been demonstrated that repeated exposure to H. pylori can induce trained immunity in the innate immune cells of the gastric mucosa, which become more responsive and better able to respond to subsequent H. pylori infections. However, interactions between H. pylori and trained immunity are intricate and produce both beneficial and detrimental effects. H. pylori infection is characterized histologically as the presence of both an acute and chronic inflammatory response called acute-on-chronic inflammation, or gastritis. The clinical outcomes of ongoing inflammation include intestinal metaplasia, gastric atrophy, and dysplasia. These same mechanisms may also reduce immunotolerance and trigger autoimmune pathologies in the host. This review focuses on the relationship between trained immunity and H. pylori and underscores the dynamic interplay between the immune system and the pathogen in the context of gastric colonization and inflammation.

Gastric Carcinoma in Autoimmune Gastritis: A Histopathologic and Molecular Study.

Patients with autoimmune gastritis (AIG) have a 13-fold risk of developing type-1 neuroendocrine tumors, whereas the risk for gastric adenocarcinoma is still uncertain. Here we describe the clinicopathologic and molecular features of a series of gastric carcinomas (GC) arising in the context of AIG. A total of 26 AIG-associated GC specimens were collected from 4 Italian Institutions. Immunohistochemistry for MUC1, MUC2, MUC5AC, MUC6, CDX2, HER2, PD-L1, CLDN18, mismatch repair (MMR) proteins, and p53 and EBV-encoded RNA (EBER) in situ hybridization were performed. Histologic and immunohistochemical features were jointly reviewed by 5 expert gastrointestinal pathologists. Next-generation sequencing analysis (TrueSight Oncology 500, Illumina) of 523 cancer-related genes was performed on 19 cases. Most tumors were diagnosed as pT1 (52%) and they were located in the corpus/fundus (58%) and associated with operative link for gastritis assessment stage II gastritis (80.8%), absence of parietal cells, complete intestinal metaplasia, and enterochromaffin-like-cell micronodular hyperplasia. Only 4 (15.4%) GCs were diagnosed during follow-up for AIG. The following histotypes were identified: 20 (77%) adenocarcinomas; 3 (11%) mixed neuroendocrine-non-neuroendocrine neoplasms, and 2 (8%) high-grade solid adenocarcinomas with focal neuroendocrine component, 1 (4%) adenocarcinoma with an amphicrine component. Overall, 7 cases (27%) showed MMR deficiency, 3 (12%) were positive (score 3+) for HER2, 6 (23%) were CLDN18 positive, and 11 (42%) had PD-L1 combined positive score ≥ 10. EBER was negative in all cases. Molecular analysis revealed 5/19 (26%) microsatellite instability (MSI) cases and 7 (37%) tumor mutational burden (TMB) high. The most frequently altered genes were TP53 (8/19, 42%), RNF43 (7/19, 37%), ERBB2 (7/19, 37% [2 amplified and 5 mutated cases]), ARID1A (6/19, 32%), and PIK3CA (4/19, 21%). In summary, AIG-associated GCs are often diagnosed at low stage in patients with longstanding misrecognized severe AIG; they often display a neuroendocrine component or differentiation, have relatively higher rates of MMR deficiency, and TMB high.

Minimally Invasive Approaches to Diagnose and Monitor Eosinophilic GI Diseases.

PURPOSE OF REVIEW: This review seeks to understand novel avenues for eosinophilic GI disease management. Biomarkers offer a unique and non-invasive approach to tracking EoE disease progression. While no biomarkers have definitively met the diagnostic criteria for eosinophilic GI diseases, some biomarkers have been shown to be associated with disease activity. Here, we examine the potential of recently studied biomarkers. RECENT FINDINGS: Current research shows advancements in blood, luminal fluid, and breath testing. Particular areas of interest include mRNA analyses, protein fingerprinting, amplicon sequence variants (ASVs), T cells and IgE receptors, eosinophilic cationic proteins, cytokines, and nitric oxide exhalation. Preliminary results showed that mucosal biomarkers, directly captured from the esophagus, may reflect the best representation of biopsy-based results, in contrast to biomarkers obtained from indirect or peripheral (blood, breath) methods. However, this is based on limited clinical studies without sufficient numbers to evaluate true diagnostic accuracy. Large-scale randomized trials are needed to fully ascertain both the optimal sampling technique and the specific biomarkers that reflect diagnostic status of the disease.

Common and disparate clinical presentations and mechanisms in different eosinophilic gastrointestinal diseases.

Eosinophilic gastrointestinal diseases (EGIDs) are a group of diseases characterized by selective eosinophil infiltration of the gastrointestinal (GI) tract in the absence of other causes of eosinophilia. These diseases are generally driven by type 2 inflammation, often in response to food allergen exposure. Among all EGIDs, the clinical presentation often includes a history of atopic disease with a variety of GI symptoms. EGIDs are traditionally separated into eosinophilic esophagitis (EoE) and non-EoE EGIDs. EoE is relatively better understood and now associated with clinical guidelines and 2 US Food and Drug Administration-approved treatments, whereas non-EoE EGIDs are rarer and less well-understood diseases without US Food and Drug Administration-approved treatments. Non-EoE EGIDs are further subclassified by the area of the GI tract that is involved; they comprise eosinophilic gastritis, eosinophilic enteritis (including eosinophilic duodenitis), and eosinophilic colitis. As with other GI disorders, the disease presentations and mechanisms differ depending on the involved segment of the GI tract; however, the differences between EoE and non-EoE EGIDs extend beyond which GI tract segment is involved. The aim of this article is to summarize the commonalities and differences between the clinical presentations and disease mechanisms for EoE and non-EoE EGIDs.

Gastric Th17 Cells Specific for H+/K+-ATPase and Serum IL-17 Signature in Gastric Autoimmunity.

Human gastric autoimmunity [autoimmune gastritis (AIG)] is characterized by inflammation of the gastric mucosa and parietal cell loss. The gastric parietal cell proton pump H+/K+-adenosine triphosphatase (H+/K+-ATPase) is the major autoantigen in AIG. Our work aimed to investigate the gastric H+/K+-ATPase-specific T helper 17 (Th17) responses in AIG and serum interleukin (IL)-17 cytokine subfamily in AIG patients, in healthy subjects [healthy controls (HCs)], and in patients with iron deficiency anemia (IDA) without AIG. We analyzed the activation of gastric lamina propria mononuclear cells (LPMCs) by H+/K+-ATPase and the IL-17A and IL-17F cytokine production in eight patients with AIG and four HCs. Furthermore, we compared serum levels of IL-17A, IL-17F, IL-21, IL-17E, IL-22, and IL-23 in 43 AIG patients, in 47 HCs, and in 20 IDA patients without AIG. Gastric LPMCs from all AIG patients, but not those from HCs, were activated by H+/K+-ATPase and were able to proliferate and produce high levels of IL-17A and IL-17F. AIG patients have significantly higher serum IL-17A, IL-17F, IL-21, and IL-17E (393.3 ± 410.02 pg/ml, 394.0 ± 378.03 pg/ml, 300.46 ± 303.45 pg/ml, 34.92 ± 32.56 pg/ml, respectively) than those in HCs (222.99 ± 361.24 pg/ml, 217.49 ± 312.1 pg/ml, 147.43 ± 259.17 pg/ml, 8.69 ± 8.98 pg/ml, respectively) and those in IDA patients without AIG (58.06 ± 107.49 pg/ml, 74.26 ± 178.50 pg/ml, 96.86 ± 177.46 pg/ml, 10.64 ± 17.70 pg/ml, respectively). Altogether, our results indicate that IL-17A and IL-17F are produced in vivo in the stomach of AIG patients following activation with H+/K+-ATPase and that serum IL-17A, IL-17F, IL-21, and IL-17E levels are significantly elevated in AIG patients but not in patients without AIG. These data suggest a Th17 signature in AIG and that IL-17A, IL-17F, IL-21, and IL-17E may represent a relevant tool for AIG management.

Immunological Perspective: Helicobacter pylori Infection and Gastritis.

Helicobacter pylori is a spiral-shaped gram-negative bacterium. Its infection is mainly transmitted via oral-oral and fecal-oral routes usually during early childhood. It can achieve persistent colonization by manipulating the host immune responses, which also causes mucosal damage and inflammation. H. pylori gastritis is an infectious disease and results in chronic gastritis of different severity in near all patients with infection. It may develop from acute/chronic inflammation, chronic atrophic gastritis, intestinal metaplasia, dysplasia, and intraepithelial neoplasia, eventually to gastric cancer. This review attempts to cover recent studies which provide important insights into how H. pylori causes chronic inflammation and what the characteristic is, which will immunologically explain H. pylori gastritis.

Lack of uniformity in reporting autoimmune gastritis among a diverse group of pathologists.

Autoimmune gastritis (AIG) is a clinicopathologic diagnosis requiring characteristic histopathology and correlation with laboratory work-up. To better understand how the diagnosis of AIG is made and reported in the pathology community, we conducted an anonymous web-based survey which was circulated among a diverse group of pathologists. Excluding trainees there were 64 respondents: 25 academic gastrointestinal pathologists (AGI, 39%), 22 academic general pathologists (AGP, 34%), 17 private general pathologists (PP, 27%). Our survey results highlighted variations in work-up and sign-out practices. The type of metaplasia needed to diagnose AIG lacked consensus. There was variation in accurate interpretation of immunostains with a trend towards more accurate diagnosis of enterochromaffin-like (ECL) cell hyperplasia by AGI (92%) and AGP (95%) than PP (71%) (p = 0.07). G-cells in antrum on neuroendocrine immunostain, a mimicker of ECL cell hyperplasia, was more frequently misdiagnosed by PP/ AGP (44%), versus AGI (12%) (p = 0.02). A triple immunostain panel (H. pylori, neuroendocrine, gastrin) was used in the work-up of AIG by 72% of AGI versus 23% AGP and 12% PP (p = 0.000061). The less-specific term "atrophic gastritis" was used in the diagnostic line more by respondents with >10 years sign-out experience compared with others (p = 0.04). In conclusion, the survey results highlighted deficiencies in the interpretation of neuroendocrine immunostains which is crucial for AIG diagnosis, as well as variation in reporting practices and definitions. Uniform criteria and terminology are needed in this field to improve communication with clinicians, resulting in appropriate testing and follow-up.

2021 year in review: Spotlight on eosinophils.

This review highlights recent advances in the understanding of eosinophils and eosinophilic diseases, particularly eosinophilic gastrointestinal diseases during the last year. The increasing incidence of diseases marked by eosinophilia has been documented and highlighted the need to understand eosinophil biology and eosinophilic contributions to disease. Significant insight into the nature of eosinophilic diseases has been achieved using next-generation sequencing technologies, proteomic analysis, and machine learning to analyze tissue biopsies. These technologies have elucidated mechanistic underpinnings of eosinophilic inflammation, delineated patient endotypes, and identified patient responses to therapeutic intervention. Importantly, recent clinical studies using mAbs that interfere with type 2 cytokine signaling or deplete eosinophils point to multiple and complex roles of eosinophils in tissues. Several studies identified distinct activation features of eosinophils in different tissues and disease states. The confluence of these studies supports a new paradigm of tissue-resident eosinophils that have pro- and anti-inflammatory immunomodulatory roles in allergic disease. Improved understanding of unique eosinophil activation states is now poised to identify novel therapeutic targets for eosinophilic diseases.

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.

Multiplexed imaging reveals an IFN-γ-driven inflammatory state in nivolumab-associated gastritis.

Immune checkpoint blockade using PD-1 inhibition is an effective approach for treating a wide variety of cancer subtypes. While lower gastrointestinal (GI) side effects are more common, upper gastrointestinal adverse events are rarely reported. Here, we present a case of nivolumab-associated autoimmune gastritis. To elucidate the immunology underlying this condition, we leverage multiplexed ion beam imaging by time-of-flight (MIBI-TOF) to identify the presence and proportion of infiltrating immune cells from a single section of biopsy specimen. Using MIBI-TOF, we analyze formalin-fixed, paraffin-embedded human gastric tissue with 28 labels simultaneously. Our analyses reveal a gastritis characterized by severe mucosal injury, interferon gamma (IFN-γ)-producing gastric epithelial cells, and mixed inflammation that includes CD8 and CD4 T cell infiltrates with reduced expression of granzyme B and FOXP3, respectively. Here, we provide a comprehensive multiplexed histopathological mapping of gastric tissue, which identifies IFN-γ-producing epithelial cells as possible contributors to the nivolumab-associated gastritis.

Mucocutaneous Manifestations in Autoimmune Gastritis: A Prospective Case-Control Study.

INTRODUCTION: Autoimmune gastritis (AIG) is associated with nutritional deficiencies, autoimmune diseases, and gastric malignancies. The aims of the study were to test the hypothesis that mucocutaneous (MC) manifestations occur more often in patients with vs without AIG and to delineate patterns of MC manifestations in AIG. METHODS: A single-center, prospective 2:1 case-control study was conducted. Cases were patients with the diagnosis of AIG based on consistent serologic and histologic findings. Controls had a normal gastric biopsy. MC manifestations were independently evaluated by 3 experienced dermatologists. We conducted a multivariable logistic regression model adjusted for age, sex, Helicobacter pylori, tobacco use, and alcohol consumption to estimate the association between AIG (vs no AIG) and MC manifestations (adjusted odds ratio; 95% confidence interval). RESULTS: We prospectively enrolled 60 cases and 30 controls (mean age 53.5 ± 15.8 vs 53.4 ± 14.5 years; 75% vs 73.3% women). The pooled prevalence of MC immune-mediated diseases was higher in patients with vs without AIG (66.7% vs 23.3%; adjusted odds ratio 12.01 [95% confidence interval: 3.51-41.13]). In patients with AIG, seropositive vs seronegative anti-intrinsic factor antibodies more often had concomitant immunological diseases with MC manifestations (100% vs 58.5%; P = 0.016). The most common MC immune-mediated diseases in AIG were Sjögren syndrome (n = 5, 8.3%), alopecia areata (n = 5, 8.3%), and vitiligo (n = 4, 6.7%). Nutritional deficiency-related MC findings, mainly xerosis, lingual, and nail disorders, were also more common in AIG. DISCUSSION: This is the first comparative study specifically designed to evaluate MC manifestations in AIG. We demonstrated that AIG is more frequently associated with both immune- and nutritional deficiency-related MC manifestations, which might have both diagnostic and therapeutic clinical implications.

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.

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.

Natural Progression of Helicobacter pylori-Negative Gastritis with Lymphoid Follicles in Children: Prospective Evaluation and Outcome.

BACKGROUND: The association of Helicobacter pylori-negative gastritis with lymphoid follicles (LFs) in children is still unclear. Therefore, we aimed to investigate the natural history and significance of H. pylori-negative gastritis with LFs in children. METHODS: We identified children with histologically proven H. pylori-negative gastritis with LFs between June 2014 and January 2017. The children were invited for a follow-up examination. The clinical, endoscopic, and histological findings of the index esophagogastroduodenoscopy (EGD) were revised and compared to the follow-up findings. RESULTS: A total of 754 children underwent EGD. Among the 48 children diagnosed with H. pylori-negative gastritis, 17 (35.41%) had gastric LFs. Eight agreed to participate in the study. The mean follow-up was 25.58 ± 4.52 (range, 20.53-35.73) months. Three children still had histologic findings of chronic gastritis with LFs. Four children had resolution of the gastritis but still had LFs, and 1 patient had resolution of both the gastritis and LFs. CONCLUSION: LFs were still present in children with H. pylori-negative gastritis after a mean follow-up of 2 years, and in some children, despite resolution of the gastritis. Therefore, this histological finding might be a non-pathological feature in children and does not need any contribution or follow-up.

Gastritis, Gastric Polyps and Gastric Cancer.

Gastric cancer is still an important disease causing many deaths worldwide, although there has been a marked reduction in prevalence during the last few decades. The decline in gastric cancer prevalence is due to a reduction in Helicobacter pylori infection which has occurred for at least 50 years. The most probable mechanism for the carcinogenic effect of H. pylori is hypergastrinemia since H. pylori infected individuals do not have increased risk of gastric cancer before the development of oxyntic atrophy. When atrophy has developed, the carcinogenic process continues independent of H. pylori. Autoimmune gastritis also induces oxyntic atrophy leading to marked hypergastrinemia and development of ECL cell neoplasia as well as adenocarcinoma. Similarly, long-term treatment with efficient inhibitors of acid secretion like the proton pump inhibitors (PPIs) predisposes to ECL cell neoplasia of a different degree of malignancy. Contrasting the colon where most cancers develop from polyps, most polyps in the stomach have a low malignant potential. Nevertheless, gastric polyps may also give rise to cancer and have some risk factors and mechanisms in common with gastric cancer. In this overview the most common gastric polyps, i.e., hyperplastic polyps, adenomatous polyps and fundic gland polyps will be discussed with respect to etiology and particularly use of PPIs and relation to gastric carcinogenesis.

The Role of TNF-α and Anti-TNF-α Agents during Preconception, Pregnancy, and Breastfeeding.

Tumor necrosis factor-alpha (TNF-α) is a multifunctional Th1 cytokine and one of the most important inflammatory cytokines. In pregnancy, TNF-α influences hormone synthesis, placental architecture, and embryonic development. It was also shown that increased levels of TNF-α are associated with pregnancy loss and preeclampsia. Increased TNF-α levels in complicated pregnancy draw attention to trophoblast biology, especially migratory activity, syncytialisation, and endocrine function. Additionally, elevated TNF-α levels may affect the maternal-fetal relationship by altering the secretory profile of placental immunomodulatory factors, which in turn affects maternal immune cells. There is growing evidence that metabolic/pro-inflammatory cytokines can program early placental functions and growth in the first trimester of pregnancy. Furthermore, early pregnancy placenta has a direct impact on fetal development and maternal immune system diseases that release inflammatory (e.g., TNF-α) and immunomodulatory factors, such as chronic inflammatory rheumatic, gastroenterological, or dermatological diseases, and may result in an abnormal release of cytokines and chemokines in syncytiotrophoblasts. Pregnancy poses a challenge in the treatment of chronic disease in patients who plan to have children. The activity of the disease, the impact of pregnancy on the course of the disease, and the safety of pharmacotherapy, including anti-rheumatic agents, in pregnancy should be considered.

The Effects of Helicobacter pylori Infection on Microbiota Associated With Gastric Mucosa and Immune Factors in Children.

Background: Helicobacter pylori infection is the main cause of chronic gastritis in children. Little is known about the effect of Helicobacter pylori on microbiota and immunity. This study was aimed at characterizing stomach microbiota and immune-regulatory properties of children with Helicobacter pylori colonization. Methods: We studied 122 children who had undergone gastric endoscopy due to gastrointestinal symptoms, 57 were diagnosed with Helicobacter pylori infection. Endoscopic mucosal biopsy samples were obtained for DNA and RNA extraction. Microbiomes were analyzed by 16S rRNA profiling, with the differentially expressed genes analyzed using RNA sequencing. The RNA-sequencing results of selected genes were validated by qRT-PCR. Results: Bacterial diversity of Helicobacter pylori-positive gastric specimens were lower than those of negative, and both groups were clearly separated according to beta diversity. Helicobacter pylori-positive group significantly reduced proportions of six phyla and eight genera; only Helicobacter taxa were more abundant in Helicobacter pylori-negative group. Gastric tissues RNA sequencing showed increased expression of multiple immune response genes in Helicobacter pylori -infection. Helicobacter pylori -infected children with restructured gastric microbiota had higher levels of FOXP3, IL-10, TGF-ß1 and IL-17A expressions, which were consistent with increased CD4+T cell and macrophagocyte, compared with non-infected children. Conclusions: Presence of Helicobacter pylori significantly influences gastric microbiota and results in lower abundance of multiple taxonomic levels in children. Meanwhile, it affects gastric immune environment and promotes the occurrence of gastritis. Clinical Trial Registration: [http://www.chictr.org.cn], identifier [ChiCTR1800015190].

OX40L/OX40 Signal Promotes IL-9 Production by Mucosal MAIT Cells During Helicobacter pylori Infection.

Mucosal associated invariant T (MAIT) cells play a critical role in Helicobacter pylori (H. pylori)-induced gastritis by promoting mucosal inflammation and aggravating mucosal injuries (1, 2). However, the underlying mechanism and key molecules involved are still uncertain. Here we identified OX40, a co-stimulatory molecule mainly expressed on T cells, as a critical regulator to promote proliferation and IL-9 production by MAIT cells and facilitate mucosal inflammation in H. pylori-positive gastritis patients. Serum examination revealed an increased level of IL-9 in gastritis patients. Meanwhile, OX40 expression was increased in mucosal MAIT cells, and its ligand OX40L was also up-regulated in mucosal dendritic cells (DCs) of gastritis patients, compared with healthy controls. Further results demonstrated that activation of the OX40/OX40L pathway promoted IL-9 production by MAIT cells, and MAIT cells displayed a highly-activated phenotype after the cross-linking of OX40 and OX40L. Moreover, the level of IL-9 produced by MAIT cells was positively correlated with inflammatory indexes in the gastric mucosa, suggesting the potential role of IL-9-producing MAIT cells in mucosal inflammation. Taken together, we elucidated that OX40/OX40L axis promoted mucosal MAIT cell proliferation and IL-9 production in H. pylori-induced gastritis, which may provide potential targeting strategies for gastritis treatment.