Prediction of Blood miRNA-mRNA Regulatory Network in Gastric Cancer

Background:The aim of the study was to suggest a high specific and sensitive blood biomarker for early GC diagnosis.Methods:the expression data of miRNAs and mRNAs were collected from the blood samples of the GC patients based on literature mining. Bioinformatics tools and databases (PANTHER, TargetScan, miRTarBase, miRDB, STRING, and Cytoscape) were used to predict the regulatory relationship. Subsequently, expression level of the selected miRNA was evaluated in the blood samples of gastritis patients to recognize the common miRNA between the GC and gastritis patients.Results:Analysis of 40 target genes by MCODE (installed in Cytoscape software) indicated 4 hub genes (WWP1, SKP2, KLHL42, and FBXO11) as a significant cluster in the PPI network related to miR-21, with Node Score Cutoff: 0.2, Degree Cutoff: 2 and K-Core: 2. In addition, the miRNA RT-qPCR results showed that, the expression level of miR-21 was significantly higher in gastritis group compared to the healthy group (p< 0.05).Conclusion:the present study clearly demonstrated the increasing level of blood miR-21 among the gastritis patients infected by H. pylori. Therefore, the altered miRNAs, especially overexpression of onco-miRs, may identify a potential link between miRNAs and pathogenesis of the H. pylori–related complications.Key Words: Blood Profiling, Gastric Cancer, H. pylori, Mir-21, Regulatory Network     

Hypomethylation of repetitive elements in blood leukocyte DNA and risk of gastric lesions in a Chinese population

BackgroundTo explore the association between hypomethylation of repetitive elements (LINE-1, Sat2, and ALU) in blood leukocyte DNA and risks of gastric lesions, and development of gastric cancer (GC), a population-based study was conducted in a high-risk area of GC in China.MaterialsMethylation levels were determined by MethyLight in 902 subjects with various gastric lesions from two cohort studies at baseline and 276 subjects with long-term follow-up data.ResultsThe frequency of LINE-1 or Sat2 hypomethylation was significantly increased in subjects with dysplasia (DYS) compared with superficial gastritis/chronic atrophic gastritis. The odds ratios (ORs) were 2.22 [95% confidence interval (CI): 1.45–3.40] for LINE-1 and 1.58 (95% CI: 1.14–2.21) for Sat2. A dose–response pattern was found for the risk of DYS and LINE-1 hypomethylation (P-trend < 0.001). Further stratified analysis indicated that the frequency of LINE-1 or Sat2 hypomethylation was higher in subjects with Helicobacter pylori infection. The ORs were 1.83 (95% CI: 1.12–2.99) for LINE-1 and 1.44 (95% CI: 1.01–2.05) for Sat2. The follow-up data indicated that the risk of progression to GC was increased in intestinal metaplasia (IM) subjects with LINE-1 hypomethylation (OR = 2.82; 95% CI: 1.17–6.77) or Sat2 hypomethylation (OR = 2.78; 95% CI: 1.15–6.74). The risk of progression to GC was also increased in DYS subjects with Sat2 hypomethylation (OR = 5.24; 95% CI: 2.00–13.74).ConclusionsThese findings suggest that hypomethylation of repetitive elements in blood leukocytes is associated with the risks of advanced gastric lesions and development of GC.     

Alkylhydroperoxide reductase of Helicobacter pylori as a biomarker for gastric patients with different pathological manifestations

The development of various gastrointestinal diseases was suggested to be associated with chronic inflammation as a consequence of Helicobacter pylori (H. pylori) infection. Our previous studies showed that an antioxidant protein alkylhydroperoxide reductase (AhpC) is an abundant and important antioxidant protein present in H. pylori. In this study we have explored the potential of utilizing antibodies to AhpC for detection of patients who are at high risks of evolving into severe outcomes of gastric malignancies after H. pylori infection. The correlation between AhpC and extents of inflammatory damage in tissues was demonstrated by immunoblotting assays and endoscopic examinations. Oxidative stress-induced high-molecular-weight (HMW) AhpC with chaperone activity in vivo was further investigated by co-immunoprecipitation, 2-dimensional gel electrophoresis (2-DE) followed by nano-liquid chromatography coupled tandem mass spectrometry (nanoLC-MS/MS). We found AhpC was consistently expressed in higher amounts in H. pylori strains isolated from patients with gastric cancer (GC) than gastritis (GA). Immunological analysis of seropositivity for AhpC indicated that positive diagnostic rates for H. pylori-infected patients with GA, gastric ulcer (GU) and GC were 68% (15/22), 100% (50/50) and 100% (50/50), respectively. In great contrast to low-molecular-weight (LMW) AhpC, HMW AhpC with chaperone function was found to distribute inside of H. pylori cells. We also found that LMW forms of AhpC were recognized by serum antibodies from GA patients whereas HMW forms of AhpC reacted mainly with those from GU and GC patients. Based on the significant difference between AhpC isolated from strains of GC and GA, it is conceivable that AhpC of H. pylori may prove to be useful as a prognostic or diagnostic protein marker to monitor varied clinical manifestations of gastrointestinal patients infected with H. pylori.     

First trimester trophoblasts forming endothelial-like tubes in vitro emulate a ‘blood vessel development’ gene expression profile

Extravillous cytotrophoblasts isolated from first trimester placenta, and immortalised cell lines derived from them, have the intrinsic ability to form endothelial-like tubes when cultured on Matrigel™ extracellular matrix. This in vitro tube formation may model placental angiogenesis and/or endovascular differentiation by trophoblasts. To interpret the relevance of this phenomenon to placental development, we used a gene expression microarray approach to identify which genes and pathways are associated with the tube-forming phenotype of HTR8/SVneo first trimester trophoblasts (HTR8-M), compared with HTR8/SVneo not forming tubes on plastic culture surface (HTR8-P). Furthermore, we used weighted gene co-expression network analysis (WGCNA) of microarray data to identify modules of co-expressed genes underlying the biological processes. There were 481 genes differentially expressed between HTR8-M and HTR8-P and these were significantly enriched for blood vessel development and related gene ontologies. WGCNA clustered the genes into 9 co-expression modules. One module was significantly associated with HTR8-M (p = 1.15E-05) and contained genes involved in actin cytoskeleton organization, cell migration and blood vessel development, consistent with tube formation on Matrigel. Another module was significantly associated with HTR8-P (p = 1.94E-05) and was enriched for genes involved in mitosis, consistent with proliferation by cells on plastic which do not differentiate. Up-regulation of angiogenesis and vascular development pathways in endovascular trophoblasts in vivo could underpin spiral artery remodelling processes, which are defective in preeclamptic pregnancies.     

Trace element levels in serum and gastric mucosa in patients with Helicobacter pylori positive and negative gastritis

BackgroundMost trace elements are inhibited by Helicobacter pylori-infection, and variations in specific element levels are linked to the development of stomach cancer. This is the first study to show the relationship between serum and tissue concentrations of twenty-five trace elements and H. pylori infection status. This study purposed to define serum and tissue trace element levels of 25 healthy individuals with Helicobacter pylori-positive gastritis and Helicobacter pylori-negative gastritis and to reveal their relationship with the disease.MethodsStudy groups consisted of sixty-two patients with Helicobacter pylori-positive, thirty-seven patients with Helicobacter pylori-negative, and thirty healthy individuals. Serum and tissue concentrations of twenty-five elements (aluminum, boron, arsenic, barium, calcium, beryllium, copper, cadmium, iron, chromium, mercury, lithium, potassium, magnesium, sodium, manganese, nickel, phosphorus, lead, scandium, strontium, selenium, tellurium, titanium, zinc) were defined by inductively coupled plasma optical emission spectrometry.ResultsExcept for copper, lithium, and strontium elements in serum samples, other trace elements differed significantly between the groups (p < 0.05). The serum chromium (p = 0.002), mercury (p = 0.001), boron (p < 0.001), and cadmium (p < 0.001) levels of H. pylori-negative gastritis and H. pylori-positive gastritis participants were significantly different, and their serum concentrations were less than 0.5 µ/l. Boron, barium, beryllium, chromium, lithium, phosphorus and strontium elements in tissue samples did not differ significantly between the groups (p > 0.05). Manganese, nickel, tellurium and titanium elements were not detected in tissue and serum samples. The mean concentrations of calcium, beryllium, chromium, iron, potassium, lithium, magnesium, scandium, and selenium were higher in the tissues of patients with H. pylori gastritis compared to healthy control tissues. Also, cadmium could not be detected in tissue samples. There was a significant difference between H. pylori-infected tissue and serum chromium levels (p = 0.001), with lower levels detected in tissue samples.ConclusionThis is the first study that we are knowledgeable of that reports the concentrations of twenty five elements in both serum and tissue samples, as well as the relationship between trace elements and Helicobacter pylori-infection status. Dietary adjustment is indicated as an adjunct to medical therapy to stabilize trace elements because Helicobacter pylori bacteria cause inflammation and impair element absorption in gastritis patients. We also think that this study will shed light on studies on the relationship between Helicobacter pylori-trace elements and serum-tissue/healthy serum-tissue trace element levels of patients with Helicobacter pylori gastritis.     

NOD1 and NOD2 Genetic Variants in Association with Risk of Gastric Cancer and Its Precursors in a Chinese Population

BackgroundGenetic variants of nucleotide-binding oligomerization domain-containing protein (NOD) may influence the outcome of Helicobacter pylori (H. pylori) infection and gastric carcinogenesis. To explore genetic variants of NOD1 and NOD2 in association with gastric cancer (GC) and its precursors, a population-based study was conducted in Linqu County, China.MethodsTagSNPs of NOD1 and NOD2 were genotyped by Sequenom MASS array in 132 GCs, and 1,198 subjects with precancerous gastric lesions, and were correlated with evolution of gastric lesions in 766 subjects with follow-up data.ResultsAmong seven tagSNPs, NOD1 rs2709800 and NOD2 rs718226 were associated with gastric lesions. NOD1 rs2709800 TG genotype carriers had a decreased risk of intestinal metaplasia (IM, OR: 0.53; 95% CI: 0.31–0.92), while NOD2 rs718226 G allele (AG/GG) showed increased risks of dysplasia (DYS, OR: 2.96; 95% CI: 1.86–4.71) and GC (OR: 2.35; 95% CI: 1.24–4.46). Moreover, an additive interaction between rs718226 and H. pylori was found in DYS or GC with synergy index of 3.08 (95% CI: 1.38–6.87) or 3.99 (95% CI: 1.55–10.22), respectively. The follow-up data indicated that NOD2 rs2111235 C allele (OR: 0.52; 95% CI: 0.32–0.83) and rs7205423 G allele (OR: 0.56; 95% CI: 0.35–0.89) were associated with decreased risk of progression in H. pylori-infected subjects.ConclusionsNOD1 rs2709800, NOD2 rs718226, rs2111235, rs7205423 and interaction between rs718226 and H. pylori infection may be related to risk of gastric lesions.     

Proteomics-based analysis of potential therapeutic targets in patients with peritoneal dialysis-associated peritonitis

BackgroundPeritoneal dialysis-associated peritonitis (PDAP) is the most common complication in peritoneal dialysis patients. We propose screening for characteristic expressed proteins in the dialysate of PDAP patients to provide clues for the diagnosis of PDAP and its therapeutic targets.MethodsDialysate samples were collected from patients with a first diagnosis of PDAP (n = 15) and from patients who had not experienced peritonitis (Control, n = 15). Data-independent acquisition (DIA) proteomic analysis was used to screen for differentially expressed proteins (DEPs). Co-expression networks were constructed via weighted gene co-expression network analysis (WGCNA) for detection of gene modules. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used for functional annotation of DEPs and gene modules. Hub proteins were validated using the parallel reaction monitoring (PRM) method.ResultsA total of 142 DEPs in the dialysate of PDAP patients were identified. 70 proteins were upregulated and 72 proteins were downregulated. GO and KEGG analysis showed that DEPs were mainly enriched in cell metabolism, glycolysis/glycogenesis and hypoxia-inducible factor-1 signaling pathway. Subsequently, a co-expression network was constructed and four gene modules were detected. Myeloperoxidase (MPO) and myeloperoxidase (HP) were the key proteins of the blue and turquoise modules, respectively. Additionally, PRM analysis showed that the expression of MPO and HP was significantly upregulated in the PDAP group compared to the non-peritonitis group, which was consistent with our proteomics data.ConclusionMPO and HP were differentially expressed in the dialysate of PDAP patients and may be potential diagnostic and therapeutic targets for PDAP.     

Brugia filariasis differentially modulates persistent Helicobacter pylori gastritis in the gerbil model

In select Helicobacter pylori-infected populations with low gastric cancer, nematode coinfections are common and both helicobacter gastritis and filariasis are modeled in gerbils. We evaluated gastritis, worm counts, tissue cytokine gene expression levels and Th1/Th2-associated antibody responses in H. pylori and Brugia pahangi mono- and coinfected gerbils. H. pylori-associated gastritis indices were significantly lower 21 weeks post-infection in coinfected gerbils (p ≤ 0.05) and were inversely proportional to worm counts (r² = ?0.62, p < 0.003). Additionally, IFN-γ, IL-1β, CXCL1, IL-4 and IL-10 mRNA levels in the gastric antrum reflected a significant host response to gastric H. pylori and as well as systemic filariasis (p ≤ 0.05). Despite increasing worm burden (p < 0.05), gastritis progressed in coinfected gerbils (p < 0.03) becoming equivalent to H. pylori-infected gerbils at 42 weeks (p = 0.7). Pro- and anti-inflammatory mediator mRNA levels were notably downregulated in B. pahangi infected gerbils below uninfected control values, suggesting hyporesponsiveness to B. pahangi. Consistent with an increasing Th1 response to H. pylori, IgG2a (p < 0.01), IL-1β (p = 0.04) and CXCL1 (p = 0.006) responses significantly increased and IL-4 (p = 0.05) and IL-10 (p = 0.04) were decreased in coinfected gerbils at 42 weeks. Initial systemic responses to B. pahangi resulted in attenuated gastritis in coinfected gerbils, but subsequent filarid-associated hyporesponsiveness appears to have promoted H. pylori gastritis.     

Genetic Polymorphisms of miR-146a and miR-27a,H. pylori Infection,and Risk of Gastric Lesions in a Chinese Population

Background

MicroRNAs (miRNAs) have been implicated in various human diseases. Single nucleotide polymorphisms (SNPs) in inflammation-related miRNA may play an important role in Helicobacter pylori (H. pylori)-induced gastric lesions. To evaluate the associations between miRNA SNPs, H. pylori and gastric lesions, a population-based study was conducted in Linqu County, China.

Methodology/Principal Findings

Based on serum miRNA array conducted in this population, two SNP loci (miR-146a rs2910164: G>C and miR-27a rs895819: T>C) were determined by polymerase chain reaction-restriction fragment length polymorphism in 2,380 participants with diverse gastric lesions. Using participants with superficial gastritis and mild chronic atrophic gastritis as the reference group, we found that rs2910164 CC carriers had a significantly increased risk of intestinal metaplasia [adjusted odds ratio (OR), 1.42; 95% confidence interval (CI), 1.03–1.97] and dysplasia (OR, 1.54; 95% CI, 1.05–2.25) compared to GG carriers, whereas no significant association was observed for rs895819. Stratified analysis by H. pylori infection indicated that rs2910164 C allele was associated with an increased risk of intestinal metaplasia and dysplasia only among individuals infected with H. pylori (CC vs. GG: OR, 1.53; 95% CI, 1.12–2.08, P for trend = 0.004). Participants who simultaneously carried variant alleles and H. pylori infection were more likely to develop intestinal metaplasia and dysplasia, although the interaction between genetic variants and H. pylori infection was not significant (P for interaction = 0.35 for rs2910164 and 0.92 for rs895819).

Conclusions/Significance

These findings suggest that miR-146a rs2910164 polymorphism may contribute to the evolution of H. pylori-associated gastric lesions in this high-risk population.     

Sarcopenia and a 5-mRNA risk module as a combined factor to predict prognosis for patients with stomach adenocarcinoma

BackgroundSarcopenia is an important factor affecting the prognostic outcomes in adult cancer patients. Gastric cancer is considered an age-related disease and is one of the leading causes of global cancer mortality. We aimed to establish an effective age-related model at a molecular level to predict the prognosis of patients with gastric cancer.MethodsTCGA STAD (stomach adenocarcinoma) and NCBI GEO database were utilized in this study to explore the expression, clinical relevance and prognostic value of age-related mRNAs in stomach adenocarcinoma through an integrated bioinformatics analysis. WGCNA co-expression network, Univariate Cox regression analysis, LASSO regression and Multivariate Cox regression analysis were implemented to construct an age-related prognostic signature.ResultsAs a result, sarcopenia is not only an unfavorable factor for OS (overall survival) in patients with tumor of gastric (HR: 1.707, 95%CI: 1.437–2.026), but also increases the risk of postoperative complications in patients with gastric cancer (OR: 2.904, 95%CI: 2.150–3.922). A panel of 5 mRNAs (DCBLD1, DLC1, IGFBP1, RNASE1 and SPC24) were identified to dichotomize patients with significantly different OS and independently predicted the OS in TCGA STAD (HR = 3.044, 95%CI = 2.078–4.460, P < 0.001).ConclusionThe study provided novel insights to understand STAD at a molecular level and indicated that the 5 mRNAs might act as independent promising prognosis biomarkers for STAD. Sarcopenia and the 5-mRNA risk module as a combined factor to predict prognosis may play an important role in clinical diagnosis.     

Serum OPN Expression for Identification of Gastric Cancer and Atrophic Gastritis and Its Influencing Factors

Background

Most studies have found that osteopontin (OPN) expression level is related to the poor prognosis of gastric cancer. However, few studies have examined the relationship between OPN expression and gastric precancerous diseases, and the potential role of OPN in the formation and development of GC. We investigated the relationships between serum OPN levels and the risks of gastric cancer (GC) and its precancerous disease, to explore the diagnostic efficacy of serum OPN level for GC and atrophic gastritis and its influencing factors.

Methods

A total of 1,452 patients were enrolled, including 609 with mild superficial gastritis (SG), 594 with atrophic gastritis (AG) and 249 with GC. The levels of serum OPN and serum Helicobacter pylori IgG antibody were detected by enzyme-linked immunosorbent assay.

Results

Serum OPN levels increased from mild SG (1.99±1.91 ng/ml) to AG (2.37±2.27 ng/ml) to GC (5.94±4.52 ng/ml) (P≤0.002), along with increasing severity of gastric disease. OPN levels were significantly higher in patients with GC compared with the non-cancer population (2.17±2.10, P<0.0001). Serum OPN level was positively correlated with age and was higher in men than women, but was not correlated with H. pylori infection status. The area under the receiver operating characteristic curve was 0.805, the optimal cutoff was 2.56 ng/ml and the sensitivity and specificity were 74.3% and 71.8%, respectively, for the ability of serum OPN to discriminate GC.

Conclusions

Serum OPN expression was closely related to the risks of GC and AG, and it might be a useful marker for the discrimination of GC. OPN level was positively correlated with age and male sex, but was not affected by H. pylori infection, and it was promoted by smoking and drinking, in patients with mild SG.     

Caveolin-1 Expression Level in Cancer Associated Fibroblasts Predicts Outcome in Gastric Cancer

Aims

Altered expression of epithelial or stromal caveolin-1 (Cav-1) is observed in various types of human cancers. However, the clinical significance of Cav-1 expression in gastric cancer (GC) remains largely unknown. The present study aims to explore the clinicopathological significance and prognostic value of both tumor cells and cancer associated fibroblasts (CAFs) Cav-1 in GC.

Methods and Results

Quantum dots immunofluorescence histochemistry was performed to examine the expression of Cav-1 in 20 cases of gastritis without intestinal metaplasia (IM), 20 cases of gastritis with IM and 286 cases of GC. Positive rates of epithelial Cav-1 in gastritis without IM, gastritis with IM and GC showed a decreasing trend (P = 0.012). Low expression of Cav-1 in CAFs but not in tumor cells was an independent predictor of poor prognosis in GC patients (P = 0.034 and 0.005 respectively in disease free survival and overall survival). Cav-1 level in tumor cells and CAFs showed no significant correlation with classic clinicopathological features.

Conclusions

Loss of epithelial Cav-1 may promote malignant progression and low CAFs Cav-1 level herald worse outcome of GC patient, suggesting CAFs Cav-1 may be a candidate therapeutic target and a useful prognostic marker of GC.     

Transforming growth factor beta 1 (TGF-β1) modulates Epstein-Barr virus reactivation in absence of Helicobacter pylori infection in patients with gastric cancer

BackgroundTransforming growth factor-beta 1 (TGF-β1), a multifunctional cytokine, acts as a key factor for Epstein-Barr virus (EBV) reactivation. We investigated the role of TGF-β1 in latent and lytic stages of EBV in relation to Helicobacter pylori infection among patients with gastric cancer (GC) and peptic ulcer disease (PUD).MethodGastric mucosal TGF-β1 expression was determined in 95 EBV positive patients with gastroduodenal pathology [GC 40, PUD 19 and non-ulcer dyspepsia (NUD) 36] by quantitative real time PCR. Presence of H. pylori infection was diagnosed when either culture or any two of three tests (RUT, histopathology and specific ureA PCR) were positive. Serum level of TGF-β1 was detected among 60 patients using ELISA.ResultsMucosal TGF-β1 mRNA expression was detected in 85 of 95 EBV positive patients and it was significantly higher in patients with GC (p = 0.042). TGF-β1 expression tended to be higher among H. pylori non-infected than infected patients (3.80 ± 6.24 vs. 2.07 ± 2.50, p = 0.085). Both mRNA and serum level had significant association with lytic stage of EBV in absence of H. pylori infection when compared with its presence (5.21 ± 4.00 vs. 2.29 ± 2.89, p = 0.040 and 842.00 [669.55] vs. 662.63 [628.76], p = 0.049; respectively).ConclusionTGF-β1 expression was significantly associated with GC. TGF-β1 was higher both at expression and translational levels in lytic EBV infection without H. pylori suggests that H. pylori infection might play important role in preventing EBV reactivation through attenuated TGF-β1 expression. This might be a “wise host defense against EBV reactivation”.     

Bone marrow‐derived mesenchymal stem cells promote Helicobacter pylori‐associated gastric cancer progression by secreting thrombospondin‐2

ObjectivesBone marrow‐derived cells (BMDCs), especially mesenchymal stem cells (MSCs), may be involved in the development of Helicobacter pylori‐associated gastric cancer (GC) in mice, but the specific mechanism remains unclear, and evidence from human studies is lacking.Materials and MethodsTo verify the role of BM‐MSCs in H pylori‐associated GC, green fluorescent protein (GFP)‐labelled BM‐MSCs were transplanted into the subserosal layers of the stomach in a mouse model of chronic H pylori infection. Three months post‐transplantation, the mice were sacrificed, and the gastric tissues were subjected to histopathological and immunofluorescence analyses. In addition, we performed fluorescence in situ hybridization (FISH) and immunofluorescence analyses of gastric tissue from a female patient with H pylori infection and a history of acute myeloid leukaemia who received a BM transplant from a male donor.ResultsIn mice with chronic H pylori infection, GFP‐labelled BM‐MSCs migrated from the serous layer to the mucosal layer and promoted GC progression. The BM‐MSCs differentiated into pan‐cytokeratin‐positive epithelial cells and α‐smooth muscle actin‐positive cancer‐associated fibroblasts (CAFs) by secreting the protein thrombospondin‐2. FISH analysis of gastric tissue from the female patient revealed Y‐chromosome‐positive cells. Immunofluorescence analyses further confirmed that Y‐chromosome‐positive cells showed positive BM‐MSCs marker. These results suggested that allogeneic BMDCs, including BM‐MSCs, can migrate to the stomach under chronic H pylori infection.ConclusionsTaken together, these findings imply that BM‐MSCs participate in the development of chronic H pylori‐associated GC by differentiating into both gastric epithelial cells and CAFs.     

Recruitment of CCR6+ Foxp3+ regulatory gastric infiltrating lymphocytes in Helicobacter pylori gastritis

Helicobacter pylori (H. pylori) infection is associated with an inflammatory response in the gastric mucosa, leading to chronic gastritis, peptic ulcers, and gastric cancer. Increased T‐cell infiltration is found at sites of H. pylori infection. The CCR6⁺ subset of CD4⁺ regulatory T cells (Tregs), a newly characterized subset of Tregs, has been reported to contribute to local immune inhibition. However, whether CCR6⁺ Tregs are present in H. pylori gastritis, and what their relationship is to disease prognosis, remains to be elucidated. In this study, gastric infiltrating lymphocytes were isolated from endoscopic biopsy specimens of H. pylori gastritis patients and analyzed. We found that in gastric infiltrating lymphocytes, CCR6⁺ CD4⁺ CD25^high Tregs, which express high levels of CD45RO, are positively associated with more severe inflammation in gastric mucosa during H. pylori infection. Furthermore, the frequency of CCR6⁺ Tregs in gastric infiltrating lymphocytes, but not CCR6^? Tregs, is significantly increased in inflamed gastric tissues, which is inversely correlated with significantly lower expression of IFN‐γ⁺ CD8⁺ T cells. We also found that the frequency of CCR6⁺ Tregs is positively correlated with the frequency of CD4⁺ IFN‐γ⁺ T cells. In addition, the frequency of CCR6⁺ Tregs, but not that of CCR6^? Tregs, is significantly correlated with increased inflammation in H. pylori gastritis. This study demonstrates that immunosuppression in H. pylori gastritis might be related to the activity of CCR6⁺ Tregs, which could influence disease prognosis.     

Gastric microbiota in gastric cancer and precancerous stages: Mechanisms of carcinogenesis and clinical value

Gastric cancer (GC) is a globally important disease. The discovery of Helicobacter pylori (H. pylori) demonstrated that the human stomach is not a sterile environment, and recent advances in molecular biology have led to the detection of large populations of microorganisms in the stomach. A growing number of studies have elucidated differences in the microbiota of patients at various stages of GC development. Evidence from insulin-gastrin transgenic (INS-GAS) and human gastric microbiota-transplanted mouse models have further demonstrated the potential causality of microbiota in the development of GC. To date, H. pylori is still thought to be the strongest risk factor for GC. H. pylori interacts with non-H. pylori commensals and affects the composition of the gastric microbiota. This review provides an overview of the relationship between the gastric microbiota and GC, including the mechanisms of microbe-associated carcinogenesis, the clinical value of the microbiota as a GC biomarker, and the potential of modulating the microbiota for GC prevention or therapy.     

Epstein Barr Virus and Helicobacter pylori Co-Infection Are Positively Associated with Severe Gastritis in Pediatric Patients

Background

H. pylori infection is acquired during childhood and causes a chronic inflammatory response in the gastric mucosa, which is considered the main risk factor to acquire gastric cancer (GC) later in life. More recently, infection by Epstein-Barr virus (EBV) have also been associated with GC. The role of EBV in early inflammatory responses and its relationship with H. pylori infection remains poorly studied. Here, we assessed whether EBV infection in children correlated with the stage of gastritis and whether co-infection with H. pylori affected the severity of inflammation.

Methodology/Principal Findings

333 pediatric patients with chronic abdominal pain were studied. From them, gastric biopsies were taken and inflammation graded according to the Sydney system; peripheral blood was drawn and antibodies against EBV (IgG and IgM anti-VCA) and H. pylori (IgG anti-whole bacteria and anti-CagA) were measured in sera. We found that children infected only by EBV presented mild mononuclear (MN) and none polymorphonuclear (PMN) cell infiltration, while those infected by H. pylori presented moderate MN and mild PMN. In contrast, patients co-infected with both pathogens were significantly associated with severe gastritis. Importantly, co-infection of H. pylori CagA+/EBV+ had a stronger association with severe MN (PR 3.0) and PMN (PR 7.2) cells than cases with single H. pylori CagA+ infection.

Conclusions/Significance

Co-infection with EBV and H. pylori in pediatric patients is associated with severe gastritis. Even single infections with H. pylori CagA+ strains are associated with mild to moderate infiltration arguing for a cooperative effect of H. pylori and EBV in the gastric mucosa and revealing a critical role for EBV previously un-appreciated. This study points out the need to study both pathogens to understand the mechanism behind severe damage of the gastric mucosa, which could identified children with increased risk to present more serious lesions later in life.