婴儿胆汁淤积症的肠道菌群变化及其与肝功能的关系

Alterations of Gut Microbiota in Cholestatic Infants and Their Correlation With Hepatic Function

Guo et al. Frontiers in Microbiology (2018)

DOI 10.3389/fmicb.2018.02682

Frontiers in Microbiology

Abstract

Cholestasis is a major hepatic disease in infants, with increasing morbidity in recent years. Accumulating evidence has revealed that the gut microbiota (GM) is associated with liver diseases, such as non-alcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma. However, GM alterations in cholestatic infants and the correlation between the GM and hepatic functions remain uninvestigated. In this study, 43 cholestatic infants (IC group) and 37 healthy infants (H group) were enrolled to detect GM discrepancies using 16S rDNA analysis. The diversity in the bacterial community was significantly lower in the IC group than that in the H group (P = 0.013). After determining the top 10 abundant genera of microbes in the IC and H groups, we found that 13 of them were differentially enriched, including Bifidobacterium, Bacteroides, Streptococcus, Enterococcus, and Staphylococcus. As compared with the H group, the IC group had a more complex GM co-occurrence network featured by three core nodes: Phyllobacterium, Ruminococcus, and Anaerostipes. In addition, the positive correlation between Faecalibacterium and Erysipelatoclostridium (r = 0.689, P = 0.000, FDR = 0.009) was not observed in the IC patients. Using the GM composition, the cholestatic patients can be distinguished from healthy infants with high accuracy [areas under receiver operating curve (AUC) > 0.97], wherein Rothia, Eggerthella, Phyllobacterium, and Blautia are identified as valuable biomarkers. Using KEGG annotation, we identified 32 functional categories with significant difference in enrichment of the GM of IC patients, including IC-enriched functional categories that were related to lipid metabolism, biodegradation and metabolism of xenobiotics, and various diseases. In contrast, the number of functions associated with amino acid metabolism, nucleotide metabolism, and vitamins metabolism was reduced in the IC patients. We also identified significant correlation between GM composition and indicators of hepatic function. Megasphaera positively correlated with total bilirubin (r = 0.455, P = 0.002) and direct bilirubin (r = 0.441, P = 0.003), whereas g-glutamyl transpeptidase was positively associated with Parasutterella (r = 0.466, P = 0.002) and negatively related to Streptococcus (r = -0.450, P = 0.003). This study describes the GM characteristics in the cholestatic infants, illustrates the association between the GM components and the hepatic function, and provides a solid theoretical basis for GM intervention for the treatment of infantile cholestasis.

关键词：小儿胆汁淤积症，16S rRNA，肝功能，细菌生物标记物，共丰度网络

婴儿胆汁淤积症是婴儿发生的一种主要肝病，发病率逐年增高，约2500人中就有一人发病。多项研究结果显示，婴儿胆汁淤积症可由肝脏感染（如甲肝、乙肝和丙肝病毒感染、爱泼斯坦巴尔病毒感染和巨细胞病毒感染）、胆道结构异常（如胆道闭锁和胆总管囊肿）、遗传性疾病（如Alagille综合征、进行性家族性肝内胆汁淤积和Agenaes综合征）和代谢紊乱（如氨基酸代谢异常、碳水化合物代谢异常和脂质代谢异常）引起。该病会进一步损害肝细胞，导致高胆红素血症、肝硬化，严重时可致命。

婴儿胆汁淤积症的一个重要特征是胆汁酸可以通过肠-肝轴与肠道菌群发生紧密相互作用。肠道菌群可以参与胆汁酸肠肝循环，并影响胆汁酸的分泌，肠道菌群分泌的胆汁盐水解酶（BSH）可以将初级胆汁酸代谢为次级胆汁酸，也可通过法尼醇X激活受体（FXR）和G蛋白偶联胆汁酸受体1（TGR5）激活初级胆汁酸的合成。胆汁酸可通过控制肠道环境的PH、抑制病原体的生长、维持肠道菌群的平衡影响肠道菌群的组成。

关于肠道菌群与肝病的关系研究较多，包括诸如酒精性脂肪肝病、非酒精性脂肪肝病、肝硬化和肝癌等，而关于肠道菌群与婴儿胆汁淤积症的研究较少。婴儿胆汁淤积症的肠道菌群特征及其与肝功能的关系尚不清楚。

本研究通过对比43例胆汁淤积症患儿与37例正常婴儿，以研究肠道菌群在胆汁淤积症患儿中的作用。

研究对象：43例胆汁淤积症患儿与37例正常婴儿。

纳入标准：

1. 3岁以下；

2. G-谷氨酰转肽酶（GGT）水平高于40 U/L，或总胆红素（TBIL）水平高于20 mmol/L。

排除标准：

1. 排除其母亲在怀孕期间患有糖尿病、高血压或慢性肝病的婴儿；

2. 排除其母亲在怀孕或哺乳期间持续接触药物或益生菌的婴儿；

3. 排除患有过敏性疾病的儿童，如食物过敏、湿疹和过敏性胃肠炎；

4. 排除在粪便样本采集前4周接触抗生素、益生菌或质子泵抑制剂的婴儿。

实验方法：纳入43例胆汁淤积症患儿，37例正常婴儿作为健康对照组。患儿在入院后的次日早晨收集新鲜粪便，健康受试者在体检期间收集新鲜粪便。

检测方法：16S rDNA 测序

研究结果：

1. 胆汁淤积症患儿的肠道菌群多样性显著低于健康对照组；

2. 差异菌属包括双歧杆菌属（Bifidobacterium）、拟杆菌属（Bacteroides）、链球菌属(Streptococcus)、肠球菌属（Enterococcus）和葡萄球菌属（Staphylococcus）；

3. 与健康对照组相比，胆汁淤积症患儿的肠道菌群的共生网络主要包括叶杆菌属（Phyllobacterium）、瘤胃球菌属（Ruminococcus）和厌氧棒状菌属（Anaerostipes）三个核心节点；

4. 肠道菌群组成可以将胆汁淤积患儿与健康婴儿高度准确区分（AUC>0.97），其中罗氏菌属（Rothia）、依格斯氏菌属（Eggerthella）、叶杆菌属（Phyllobacterium）和劳特氏菌属（Blautia）可作为生物标志物；

5. 肠道菌群与肝功能标志物有相关性，其中巨球型菌属（Megasphaera）与总胆红素（r=0.455，p=0.002）和直接胆红素（r=0.441，p=0.003）呈正相关；G-谷氨酰转肽酶与Parasutterella (r = 0.466, P = 0.002)呈正相关、与链球菌属(r = -0.450, P = 0.003)呈负相关。

结论： 本研究描述了胆汁淤积症患儿的肠道菌群特征，阐明了肠道菌群组成与肝功能的关系，为肠道菌群干预治疗小儿胆汁淤积症提供了坚实的理论依据。

FIGURE 1 | Principal component analysis (PCA) distribution and bacterial diversity in IC and healthy infants. (A) Using PCA analysis, the samples from the IC group were clustered together, and they were separated from those of the H group. The GM of the participants predominantly included Bacteroides, Bifidobacterium, and Enterococcus. (B) The diversity in the bacterial community was significantly lower in the IC infants (2.222±0.790) than that in the H group (2.669±0.753) (P = 0.013).

图1. 胆汁淤积症患儿和健康婴儿的主成分分析（PCA）分布和细菌多样性。(A) PCA分析显示，胆汁淤积症患儿的肠道菌群主要包括拟杆菌属、双歧杆菌属和肠球菌属。(B) 胆汁淤积症患儿菌群的多样性（2.222±0.790）明显低于健康对照组组（2.669±0.753）（P=0.013）。

知几未来研究院正在搭建一个“疾病-肠道菌群”知识库。

你可以在公众号菜单栏“学术工具“版块直接查阅疾病和肠道菌群的相关信息；

也可以在公众号对话框回复疾病名称，如“IBD”或“肠易激综合征”，查看与疾病相关的菌群；

或回复菌种名称，如“双歧杆菌”或“Hp”，查看与细菌相关的疾病。

👇👇👇点击阅读原文，了解更多人体微生态研究。