Genome-wide DNA methylation profiles in noncancerous gastric mucosae with regard to Helicobacter pylori infection and the presence of gastric cancer

Background and Aims: To determine genome‐wide DNA methylation profiles induced by Helicobacter pylori (H. pylori) infection and to identify methylation markers in H. pylori‐induced gastric carcinogenesis. Methods: Gastric mucosae obtained from controls (n = 20) and patients with gastric cancer (n = 28) were included. A wide panel of CpG sites in cancer‐related genes (1505 CpG sites in 807 genes) was analyzed using Illumina bead array technology. Validation of the results of Illumina bead array technique was performed using methylation‐specific PCR method for four genes (MOS, DCC, CRK, and PTPN6). Results: The Illumina bead array showed that a total of 359 CpG sites (269 genes) were identified as differentially methylated by H. pylori infection (p < .0001). The correlation between methylation‐specific PCR and bead array analysis was significant (p < .0001, Spearman coefficient = 0.5054). Methylation profiles in noncancerous gastric mucosae of the patients with gastric cancer showed quite distinct patterns according to the presence or absence of the current H. pylori infection; however, 10 CpG sites were identified to be hypermethylated and three hypomethylated in association with the presence of gastric cancer regardless of H. pylori infection (p < .01). Conclusions: Genome‐wide methylation profiles showed a number of genes differentially methylated by H. pylori infection. Methylation profiles in noncancerous gastric mucosae from the patients with gastric cancer can be affected by H. pylori‐induced gastritis. Differentially methylated CpG sites in this study needs to be validated in a larger population using quantitative methylation‐specific PCR method.     

Immune and proliferative cellular responses to Helicobacter pylori infection in the gastric mucosa of Mexican children

BACKGROUND: Helicobacter pylori infection occurs mostly during childhood, but few studies on this age group have addressed the innate immune and the proliferative response to this infection. Mexico has a high H. pylori prevalence in children, but a low risk of gastric cancer. The aim of this work was to study the cellular responses of the gastric mucosa to this infection in Mexican children. METHODS: Antral and corpus gastric biopsies were obtained from 44 H. pylori-infected children (mean age 12 +/- 3.2 years) and 44 uninfected children (mean age 10 +/- 3 years). Mucosal cellular responses were studied by immunohistochemistry, using anti-Ki67 antibodies for proliferation studies, antihuman tryptase for mast cells, and antihuman CD68 for macrophages. T and B lymphocytes were stained with a commercial integrated system. The intensity of cellular responses was estimated histologically using the software KS300. RESULTS: Epithelium proliferation and infiltration of macrophages and T and B lymphocytes were significantly higher in H. pylori-infected than in uninfected children. A balanced increase of CD4, CD8, and CD20 lymphocytes was observed in infected children. However, activated mast cells were decreased, and infiltration of neutrophil and mononuclear cells was low. Epithelial proliferation was associated with polymorphonuclear infiltration but not with infiltration of macrophages or lymphocytes. Inflammation and proliferation was higher in CagA (+)-infected children. CONCLUSIONS: Mexican children respond to H. pylori infection with a low inflammatory response, a balanced increase of T and B lymphocytes, and a high regenerative activity.     

Epigenetic changes in gastric cancer induction by Helicobacter pylori

Epigenetic disorder mechanisms are one of the causes of cancer. The most important of these changes is the DNA methylation, which leads to the spread of Helicobacter pylori and inflammatory processes followed by induction of DNA methylation disorder. Mutations and epigenetic changes are the two main agents of neoplasia. Epithelial cells infection by H. pylori associated with activating several intracellular pathways including: MAPK, NF-κB, Wnt/β-catenin, and PI3K are affects a variety of cells and caused to an increase in the production of inflammatory cytokines, changes in apoptosis, proliferation, differentiation, and ultimately leads to the transformation of epithelial cells into oncogenic. The arose of free radicals impose the DNA cytosine methylation, and NO can increase the activity of DNA methyltransferase. H. pylori infection causes an environment that mediates inflammation and signaling pathways that probably caused to stomach tumorigenicity. The main processes that change by decreasing or increasing the expression of various microRNAs expressions include immune responses, apoptosis, cell cycle, and autophagy. In this review will be describe a probably H. pylori roles in infection and mechanisms that have contribution in epigenetic changes in the promoter of genes.     

Protein changes in gastric epithelial cells RGM-1 in response to Helicobacter pylori infection

Helicobacter pylori-induced inflammation significantly increases the risk of gastric cancer. To investigate the role of H. pylori infection in gastric epithelial cell carcinogenesis, flow cytometry was used to analyze the apoptosis of gastric epithelial cells infected by H. pylori. Next, LTQ MS mass spectrometry (MS) was applied to identify protein changes in gastric epithelial cells infected with H. pylori, and then bioinformatics was adopted to analyze the cellular localization and biological function of differential proteins. LTQ MS/MS successfully identified identified 22 differential proteins successfully, including 20 host-cell proteins and two H. pylori bacterial proteins. Also, human proteins were located in all areas of cells and involved in various cell biological functions. The oncogene proteins p53, p16, and C-erbB-2 proteins in H. pylori-infected RGM-1 cells were remarkably increased from the analysis by Western blot analysis. H. pylori infection of gastric epithelial cells leads to changes in various protein components in the cell, and enhances the expression of oncogene proteins, thereby increasing the possibility of possibility of carcinogenesis of H. pylori infection.     

Long-standing gastric mucosal barrier dysfunction in Helicobacter pylori-induced gastritis in mongolian gerbils

BACKGROUND AND AIMS: Helicobacter pylori infection causes chronic gastritis and leads to peptic ulcer and gastric adenocarcinoma. An impaired gastric mucosal barrier could be involved in these processes. Our aim was to investigate gastric barrier function in H. pylori-induced gastritis. METHODS: Stripped gastric mucosal tissues of H. pylori-infected Mongolian gerbils (4 weeks and 70 weeks after inoculation, respectively) and controls were mounted in Ussing chambers. (51)Cr-EDTA (paracellular probe) and horseradish peroxidase (HRP, protein antigen) were used to assess mucosal barrier function. The electrophysiological parameters of the mucosa (transepithelial potential, short circuit current, and transepithelial resistance) were monitored as measurements of barrier integrity and viability. Tissue histology was performed to assess inflammation. RESULTS: In the antrum, both short-term gastritis [4.68 (3.88-5.74) x 10(-6) vs. control 2.86 (2.34-3.77) x 10(-6) cm/s, p <.001] and gastritis of long-standing [5.72 (3.88-10.94) x 10(-6) cm/s, p <.001 vs. control] showed increased permeability to (51)Cr-EDTA. In long-standing antral gastritis there was also an increased HRP flux [9.01 (2.98-45.02) vs. control 0.52 (0.06-1.20) pmol/h/cm(2), p <.001]. In the corpus, permeability to (51)Cr-EDTA was increased only in long-standing gastritis [4.63 (3.64-7.45) x 10(-6) vs. control 2.86 (2.12-3.98) x 10(-6) cm/s, p <.01]. Gastric mucosal permeability to (51)Cr-EDTA was correlated to histological inflammation and inflammatory activity. The levels of serum anti-H. pylori immunoglobulin G were positively correlated to HRP flux and (51)Cr-EDTA permeation. CONCLUSIONS: Helicobacter pylori-induced gastritis in Mongolian gerbils was associated with a long-standing gastric mucosal barrier dysfunction. The barrier defect extended from the antrum into the corpus over time. This impaired barrier function may contribute to perpetuation of chronic inflammation and may be involved in H. pylori-associated carcinogenesis.     

Current information on the association of Helicobacter pylori with autophagy and gastric cancer

Helicobacter pylori (H. pylori) is a Gram-negative bacterium and causative agent of gastric cancer. H. pylori induce defective autophagy or inhibit it by means of CagA and vacuolating cytotoxin A (VacA) toxins leading to the gastric cancer induction. Impaired or defective autophagy leads to the accumulation of cytotoxic materials, such as ROS and P62 that lead to increased mutations in the DNA, genome instability, and risk of cancer formation. H. pylori CagA may inhibit autophagy through the c-Met-PI3k/Akt-mTOR signaling pathway. However, VacA induces autophagy by some signaling pathways. In the gastric epithelial cells, VacA is a necessary and sufficient factor for the creation of autophagy. While CagA is a negative regulator of this phenomenon, the elimination of this gene from H. pylori has increased autophagy and the production of inflammatory cytokines is reduced. In gastrointestinal cancers, some of the microRNAs (miRNAs) act as tumor suppressors and some other are oncogenes by regulating various genes expression. H. pylori can also modify autophagy through a mechanism that includes the function of miRNAs. In autophagy, oncogenic miRNAs inhibit activation of some tumor suppressor signaling pathways (e.g., ULK1 complex, Beclin-1 function, and Atg4 messaging), whereas tumor suppressor miRNAs can block the activation of oncogenic signaling pathways. For instance, Beclin-1 is negatively regulated by miRNA-376b (oncogenic miRNA) and miRNA-30a (tumor suppressor miRNA). Similarly, Atg4 by miRNA-376b (oncogenic miRNA) and miRNA-101 (tumor suppressor miRNA). So, this apparent paradox can be explained as that both Beclin-1 and Atg4 play different roles in a particular cell or tissue.     

甲烷氢呼气试验对原发性肾病综合征患儿小肠细菌过度生长的检测

通过甲烷氢呼气试验对原发性肾病综合征（PNS）患儿小肠细菌过度生长情况进行评估,探索PNS患儿小肠细菌情况。

本研究于2021年3月至2022年3月招募30例PNS患儿（PNS组）和34例体检者（对照组）为研究对象,采用甲烷氢呼气试验检测受试者小肠的菌群生长情况。分析PNS与小肠细菌生长情况的相关性。

PNS组共有16名PNS患儿合并小肠细菌过度生长（SIBO）,SIBO患病率为53.3%（95% CI：11.1%～89.7%）;而对照组有26.5%的儿童患有SIBO,组间差异有统计学意义（χ² = 4.831 4,P = 0.027 9）。两组儿童年龄、性别、常住地比较差异均无统计学意义（均P＞0.05）。PNS合并SIBO的患儿白细胞水平显著低于未合并SIBO的患儿（F = 6.279 7,P = 0.020 1）。Pearson分析显示,PNS组中SIBO阳性患儿服用乳果糖后呼出气体变化量与血清中胆固醇水平具有相关性（P＜0.05）。

PNS患儿更容易发生SIBO,临床可对此类患者进行针对性治疗。