2型糖尿病患者的粪便菌群特征及其在血糖控制中的中介效应

【Background】Gut microbiota has been associated with the risk of type 2 diabetes mellitus (T2DM). Its role in the progress of the disease, however, remains unclear.【Objectives】To identify specific fecal microbiota profiles related to certain characteristics of Chinese patients with T2DM, and examine the effect of gut microbiota in glycemic control in the population and possible mechanisms underlying.【Methods】Baseline and follow-up survey data for 400 T2DM patients will be derived from an ongoing randomized controlled trial. Information on demographic characteristics, lifestyle factors (diet, physical activity), biochemical tests [blood glucose, hemoglobin A1c (HbA1c), blood lipids, liver and kidney functions] and treatments has been collected for each patient at baseline and follow-up surveys at 3-, 6- and 12-month of intervention. Fecal samples have also been collected at baseline and 12-month surveys and will be used to extract bacteria DNA. 16S rDNA sequencing will be performed using an Illumina Miseq system. Richness (number of observed species) and alpha diversity metrics (Chao1, Shannon index and phylogenetic diversity whole-tree) will be calculated using the Quantitative Insights Into Microbial Ecology（QIIME）pipeline. Mediation analysis will be conducted to evaluate the impact of specific fecal microbiota in associations of glycemic control methods such as diet, physical activities and use of anti-diabetes drugs with HbA1c level.【Expected Results】Richness and alpha diversity metrics of specific fecal microbiota related to a certain characteristic of T2DM patients; mediation effect of specific fecal microbiota on glycemic control in Chinese T2DM patients.【Significance】Our results will help to better understand the biological mechanisms underlying glycemic control in Chinese patients with T2DM, and aid to develop a novel effective intervention in the population.

【背景】肠道菌群对2型糖尿病（T2DM）的发生发展均有重要影响，其在血糖控制中的作用倍受关注。【目的】分析不同特征T2DM患者的粪便菌群特征和变化，探索其影响血糖控制的机理。【方法】基于前期开展的一项随机对照试验，利用已收集的400名T2DM患者基线及干预1年后的生活方式信息（膳食、体力活动等）、实验检测结果（血糖、血脂、肝肾功能）、临床治疗信息和新鲜粪便样品，提取菌群总DNA，利用Illumina Miseq测序平台进行16S rDNA测序，进行后续α-多样性、PCA、群落结构、KEGG注释、LEfSe组间差异比较等生物信息学分析，比较不同膳食模式、体力活动强度、不同降糖药使用者肠道微生物的差异及变化；采用中介分析方法评估粪便菌群在这些降糖措施中的中介效应。【预期结果】不同特征患者的肠道菌群谱及在血糖控制中的中介效应。【意义】揭示T2DM患者血糖控制不佳的原因和机理，为精准降糖提供依据。

背景：肠道菌群对2型糖尿病（T2DM）的发生发展有重要影响，菌群失调与T2DM及并发症的发生倍受关注。有待探索肠道菌群对T2DM患者血糖控制的影响。主要研究内容：基于前期一项RCT，利用已收集的400名T2DM患者基线及干预期间的膳食、体力活动、HbA1水平和2次随访采集的粪便样本，对菌群16S rDNA V4高变区测序，进行生物信息学分析，比较不同HbA1c水平、膳食、体力活动患者肠道微生物的差异，评估菌群在膳食和体力活动降糖效果中的中介效应。重要结果：T2DM患者的HbA1c水平与肠道菌群多样性及丰度有显著关联；即使日常膳食纤维素摄入较低，相对较高摄入量与Chao1和Shannon指数呈负向关联，主要表现为有害菌群的减少；膳食纤维摄入量>7.2克/天的患者中，Desulfovibrio在膳食纤维-HbA1c关联中有显著负向中介效应，但该效应不足以引起HbA1c的显著改变。关键数据：1)高HbA1c患者有更低的α多样性，且Succinivibrio和Desulfovibrio丰度较高，而Haemophilus和Lachnospiraceae丰度较低。2)膳食纤维对菌群多样性有显著影响。第1次随访摄入量>7.2克/天者中，膳食纤维与Chao1[β(95%CI): -5.07(-9.59, -0.56)]和Shannon [β(95%CI): -0.06(-0.11, -0.02)]指数的负向关联更显著；第2次随访同样发现膳食纤维与Chao1的显著负向关联，且高摄入组比低摄入组Chao1指数更低。纵向分析亦发现高-高摄入组较低-低组的Chao1指数更低。3)膳食纤维摄入较低者Collinsella和Desulfovibrio丰度较高，而Bacteroides丰度较低。第1次随访发现Collinsella与膳食纤维呈负向关联[β(95%CI):-0.13(-0.21,-0.06) ]，且在摄入量≥7.2克/天患者中更显著。摄入量较高组中Desulfovibrio在膳食纤维-HbA1c关联中呈显著的负向中介效应[β(95% CI): -0.020(-0.044,-0.004)]。科学意义：研究结果证实了肠道菌群在T2DM患者血糖控制中的作用，为提出新的干预措施提供了依据。