幽门螺杆菌感染对正常胃部菌群多样性和组成的影响

Effects of Helicobacter pylori on the composition of normal gastric microbiota

目的通过高通量测序分析,探讨幽门螺杆菌(Helicobacter pylori)感染在正常胃部菌群多样性和组成中的差异。方法选择2017年10月-2018年1月在本院就诊的胃镜体检受试者40例,其中H.pylori阳性20例,阴性20例,均无阳性体征,收集胃液样本行胃部菌群MiSeq高通量测序分析。结果H.pylori感染组α-多样性指数Shannon(t=-6.690,P<0.001)和Simpson(t=-3.673,P=0.002)显著改变,显示胃部菌群多样性降低;菌群丰富度指数如PD Whole tree(t=-2.282,P=0.008),Chao1(t=-2.173,P=0.036)和Observed species(t=-2.627,P=0.012)在H.pylori阳性受试者中显著降低;β-多样性指数PCA分析可显著区分两组,结果显示H.pylori感染胃部菌群显著改变。LEfSe组成差异分析发现,胃部菌群组成亦发生了显著改变,H.pylori感染阳性组中变形菌门细菌显著升高,而厚壁菌门、拟杆菌门、放线菌门等显著降低;在属水平上,螺杆菌属(Helicobacter)、盐单胞菌属(Halomonas)、希瓦内拉菌属(Shewanella)和葡萄球菌属(Staphylococcus)等显著富集,而普氏菌属(Prevotella)、假单胞菌属(Pseudomonas)、芽胞杆菌属(Bacillus)等显著降低(LDA>2,P<0.05)。PiCRUSt菌群功能预测分析发现,H.pylori阳性的胃部菌群细菌分泌系统、脂多糖合成蛋白、脂多糖合成、细菌毒素、癌症信号通路的表达显著升高,而氨基酸代谢通路显著降低,这与胃癌的发生发展具有密切的联系。结论H.pylori感染是影响正常胃部菌群多样性和组成的重要因素,这些改变可能与胃癌发生发展及预后密切相关。

Objective To investigate the effect of Helicobacter pylori(H.pylori)infection on the diversity and composition of normal gastric microbiota with high-throughput sequencing technique.Methods Forty patients who were in our hospital for gastroscopy examination from October 2017 to January 2018 were enrolled,including 20 H.pylori-positive cases and 20 H.pylori-negative cases.The gastric juice were analyzed using MiSeq high-throughput sequencing.Results The alterations ofα-diversity indices such as Shannon(t=6.690,P<0.001)and Simpson(t=-3.673,P=0.002)indicated that H.pylori infection significantly reduced the bacterial diversity of gastric microbiota.The bacterial richness indices such as PD Whole tree(t=-2.282,P=0.008),Chao1(t=-2.173,P=0.036)and Observed species(t=-2.627,P=0.012)also decreased significantly in H.pylori positive cases.In addition,theβ-diversity index such as PCA analysis also distinguished the two groups significantly.LEfSe analysis showed that the composition of gastric microbiota also changed significantly.At the phylum level,Proteobacteria increased significantly in the H.pylori-positive group,while Firmicutes,Bacteroidetes,Actinobacteria,decreased obviously.At the genus level,Helicobacter,Halomonas,Shewanella and Staphylococcus were significantly enriched in the H.pylori-positive group,while Prevotella,Pseudomonas,Bacillus and other bacteria significantly reduced(LDA>2,P<0.05).PiCRUSt microbial function prediction showed that bacterial secretion system,lipopolysaccharide synthesis protein,lipopolysaccharide synthesis,bacterial toxins,and pathways in cancer significantly increased in the H.pylori-positive group(P<0.05),while the amino acid metabolism pathway significantly reduced.Conclusion H.pylori infection is one of the important factors affecting the diversity and composition of normal gastric microbiota,which may be related to the development and prognosis of gastric cancer.