目的 通过分析自身免疫性肝病(AILD)患者肝组织中是否存在特异性细菌,拟为AILD发病机制的研究提供线索.方法 纳入2017年8月至2018年8月在天津医科大学总医院消化科就诊的12例AILD患者[其中4例自身免疫性肝炎(AIH),4例原发性胆汁性胆管炎(PBC),4例PBC-AIH重叠综合征(OS)]和4例肝囊肿患者(对照),均行肝活组织穿刺检查.对所获无菌肝组织进行16SrRNA基因测序,基于线性判别分析效应量找出差异菌,以Spearman相关性分析探讨肝脏菌群与疾病的相关性,并对测得的16S rRNA基因序列进行代谢功能的预测.结果 16例纳入患者肝组织中均检测到细菌.在种水平,AIH组莱比托游动球菌丰度为0.100%,高于其余3组的0,差异有统计学意义[线性判别分析(LDA) =3.31,P=0.034];PBC组嗜热厌氧芽孢杆菌相对丰度为0.200%,高于其余3组的0.100%,差异有统计学意义(LDA=3.34,P=0.014).铜绿假单胞菌PAO1、坚强芽孢杆菌、土壤短芽孢杆菌、鲍曼不动杆菌、玉米鞘氨醇单胞菌、肠沙门菌的相对丰度与血清GGT水平均呈负相关(r=-0.68、-0.68、-0.67、-0.68、-0.68、-0.66,P均<0.01).与肝囊肿组患者相比,AILD患者脂质代谢途径减弱.血清低密度脂蛋白和总胆固醇的水平与不饱和脂肪酸的生物合成均呈负相关(r=-0.55、-0.65,P均<0.05).结论 AIH组和PBC组患者肝组织中存在特异性细菌.与AILD发病机制密切相关的肝脏微生物群,可能是一种潜在的诊断和治疗靶点.
Objective To provide clues for the study on the mechanism of autoimmune liver disease (AILD) by exploring the existence of specific bacteria in liver tissues of AILD patients.Methods From August 2017 to August 2018,at Department of Gastroenterology arnd Hepatology,Tianjin Medical University General Hospital,a total of 12 patients diagnosed as AILD (four autoimmune hepatitis (AIH),four primary biliary cirrhosis (PBC) and four PBC-AIH overlap syndrome (OS)) and four patients with hepatic cyst (control group) were enrolled and all the patients underwent liver biopsy.16S rRNA gene sequencing was carried out in the obtained aseptic liver tissues.Linear discriminant analysis effect size was used to find out the specific bacteria.Spearman correlation analysis was performed to analyze the correlation between the liver microbiota and the disease.The metabolic function of the 16S rRNA gene sequences was also predicted.Results Bacteria were detected in the liver tissues of all the 16 patients.At the species level,the abundance of Planococcus rifietoensis of AIH group was 0.100%,which was higher than those of other three groups (0),and the difference was statistically significant (linear discriminant analysis (LDA) =3.31,P =0.034).The abundance of Anoxybacillus flavithermus of PBC group was 0.200%,which was higher than those of other three groups (0.100%),and the difference was statistically significant (LDA =3.34,P =0.014).The abundance of Pseudomonas aeruginosa PAO1,Bacillus firmus,Brevibacillus agri,Acinetobacter baumannii,Sphingomonas zeae and Salmonella enterica were significantly negatively correlated with serum level of γ-glutamyl transferase (r=-0.68,-0.68,-0.67,-0.68,-0.68 and-0.66,all P <0.01).Compared with that of the hepatic cyst group,the lipid metabolism of AILD patients decreased.The levels of serum low density lipoprotein and total cholesterol were significantly negatively correlated with the biosynthesis of unsaturated fatty acids (r =-0.55 and-0.65,both P < 0.05).Conclusions There exist specific bacteria in the liver tissues of AIH and PBC groups.The liver microbiota which is closely related with the pathogenesis of AILD might be a potential therapeutic target and diagnostic biomarker.