Objective Gastric carcinoma development is triggered by Helicobacter pylori. Chronic H. pylori infection leads to reduced acid secretion, which may allow the growth of a different gastric bacterial community. This change in the microbiome may increase aggression to the gastric mucosa and contribute to malignancy. Our aim was to evaluate the composition of the gastric microbiota in chronic gastritis and in gastric carcinoma. Design The gastric microbiota was retrospectively investigated in 54 patients with gastric carcinoma and 81 patients with chronic gastritis by 16S rRNA gene profiling, using next-generation sequencing. Differences in microbial composition of the two patient groups were assessed using linear discriminant analysis effect size. Associations between the most relevant taxa and clinical diagnosis were validated by real-time quantitative PCR. Predictive functional profiling of microbial communities was obtained with PICRUSt. Results The gastric carcinoma microbiota was characterised by reduced microbial diversity, by decreased abundance of Helicobacter and by the enrichment of other bacterial genera, mostly represented by intestinal commensals. The combination of these taxa into a microbial dysbiosis index revealed that dysbiosis has excellent capacity to discriminate between gastritis and gastric carcinoma. Analysis of the functional features of the microbiota was compatible with the presence of a nitrosating microbial community in carcinoma. The major observations were confirmed in validation cohorts from different geographic origins. Conclusions Detailed analysis of the gastric microbiota revealed for the first time that patients with gastric carcinoma exhibit a dysbiotic microbial community with genotoxic potential, which is distinct from that of patients with chronic gastritis.

中文翻译：

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胃微生物群落分析揭示了与癌症相关的失调微生物群

目的胃癌的发生是由幽门螺杆菌引发的。慢性幽门螺杆菌感染导致胃酸分泌减少，这可能会导致不同的胃细菌群落生长。微生物组的这种变化可能会增加对胃粘膜的攻击并导致恶性肿瘤。我们的目的是评估慢性胃炎和胃癌中胃微生物群的组成。设计 使用二代测序，通过 16S rRNA 基因图谱对 54 名胃癌患者和 81 名慢性胃炎患者的胃微生物群进行了回顾性研究。使用线性判别分析效应大小评估两个患者组的微生物组成差异。通过实时定量 PCR 验证了最相关的分类群与临床诊断之间的关联。微生物群落的预测功能分析是通过 PICRUSt 获得的。结果胃癌菌群的特点是微生物多样性减少，螺杆菌丰度降低，其他细菌属富集，主要以肠道共生菌为代表。将这些分类群组合成微生物生态失调指数表明，生态失调具有很好的区分胃炎和胃癌的能力。微生物群功能特征的分析与癌中亚硝化微生物群落的存在相一致。主要观察结果在来自不同地理来源的验证队列中得到证实。