慢传输型便秘中动力相关共生菌种的筛选与功能验证

Intestinal motility disorders play an important part of gastrointestinal dysfunction, of which the management remains challenging. Traditional prokinetic agents are commonly used to alleviate symptoms, with most patients using them on at least a monthly basis. Owing to insufficient efficacy, inconsistent symptom response, and concerns about adverse effects, up to 47% of patients are not completely satisfied with such treatments. Recently, we observed dysbiosis was frequently complicated in constipation and gut microbiota could affect gastrointestinal transit. Our clinical trial of fecal microbiota transplantation (FMT) for slow transit constipation (STC) also confirmed that modifying the intestinal flora may be an attractive treatment option for intestinal motility disorders. This study aims at developing this new drug and could be divided into four steps as follow: Firstly, compare the differences of gut microbiome between STC patients and healthy controls by metagenomics and metabonomics. Secondly, observe the dynamic changes of gut microbiota in STC patients undergone FMT during the 12-week follow-up, and find out the relations between the clinical remission and some specific microbiota species. Thirdly, select the homologous strains from current bacterial library according to the above results, and validate the effect of each strain on intestinal motility in vivo using SPF mice. For some species which could not be obtained from bacterial library, we have to separate them ourselves. Lastly, freeze-dry the final selected strains and encapsule using acid-resistant hypromellose capsules. If succeed, we hope to launch a phase II randomized controlled trial.

肠动力障碍是肠功能障碍的重要组成部分，也是临床一大难题。传统促动力药不良反应明显，不宜长期使用。最新研究表明肠道菌群能够显著影响肠动力。本课题组开展的利用粪菌移植技术重建肠道菌群治疗慢传输型便秘的临床研究也初步证实，调节肠道菌群对改善肠动力安全有效。为了进一步开发针对肠动力障碍的微生态制剂，本研究旨在利用宏基因组学和代谢组学深入分析肠动力障碍（慢传输型便秘）病理状态下的肠道菌群特点，初步筛选影响肠动力的菌种范围；利用粪菌移植治疗肠动力障碍（慢传输型便秘）的临床研究，动态观察肠道菌群的变化，进一步筛选影响肠动力的关键菌种；继而从现有菌库中购买或自行分离出对应菌种下目前可获得的数个菌株，利用SPF小鼠（无菌小鼠本身存在肠神经丛发育异常）对其逐一进行体内验证，确定最终的关键菌株；将筛选出的促动力菌株用抗酸的羟丙甲纤维素胶囊包裹，期望开发一种用于肠动力障碍的新型活菌胶囊，并开展Ⅱ期临床研究。

肠动力障碍是胃肠功能障碍的重要组成部分，也是当前临床的一大难题。传统促动力药不良反应明显，不宜长期使用。最新动物与人体研究均表明肠道菌群能够显著影响肠动力。通过课题组研究发现菌群移植后第4周便秘患者肠道菌群多样性指数趋于平稳，随后逐渐恢复到治疗前状态；常规治疗组菌群多样性未见显著变化，FMT组症状改善的患者肠道菌群组成特点趋近于供体肠道菌群组成。研究证实了FMT治疗慢传输型便秘安全、有效，短期治疗效果优于常规对照组。进一步研究发现慢传输型便秘患者肠道菌群和健康组有显著差异，初步筛选出以肠道产丁酸菌 (Roseburia intestinalis)为核心的关键菌种。通过培养该菌株，利用动物用小型羟丙甲纤维素胶囊包裹，将目标菌逐一移植给SPF C57BL-6小鼠；将筛选出的促动力菌株用抗酸的羟丙甲纤维素胶囊包裹，制成活菌胶囊。研究发现移植后模型鼠在24小时排便粒数、粪便干湿重以及粪便长度、全消化道运输时间和结肠运输时间及肠道平滑肌收缩力方面发现显著变化。本课题后续会聚焦在揭示肠道菌群治疗STC的机制，围绕产丁酸菌-色氨酸/TRPA1通路开展机制研究；同时开展肠道活菌制剂的动物实验及临床研究，开辟肠道微生物治疗便秘新方法。