The Effect of Diet and Exercise on Intestinal Integrity and Microbial Diversity in Mice

BackgroundThe gut microbiota is now known to play an important role contributing to inflammatory-based chronic diseases. This study examined intestinal integrity/inflammation and the gut microbial communities in sedentary and exercising mice presented with a normal or high-fat diet.MethodsThirty-six, 6-week old C57BL/6NTac male mice were fed a normal or high-fat diet for 12-weeks and randomly assigned to exercise or sedentary groups. After 12 weeks animals were sacrificed and duodenum/ileum tissues were fixed for immunohistochemistry for occludin, E-cadherin, and cyclooxygenase-2 (COX-2). The bacterial communities were assayed in fecal samples using terminal restriction fragment length polymorphism (TRFLP) analysis and pyrosequencing of 16S rRNA gene amplicons.ResultsLean sedentary (LS) mice presented normal histologic villi while obese sedentary (OS) mice had similar villi height with more than twice the width of the LS animals. Both lean (LX) and obese exercise (OX) mice duodenum and ileum were histologically normal. COX-2 expression was the greatest in the OS group, followed by LS, LX and OX. The TRFLP and pyrosequencing indicated that members of the Clostridiales order were predominant in all diet groups. Specific phylotypes were observed with exercise, including Faecalibacterium prausnitzi, Clostridium spp., and Allobaculum spp.ConclusionThese data suggest that exercise has a strong influence on gut integrity and host microbiome which points to the necessity for more mechanistic studies of the interactions between specific bacteria in the gut and its host.背景 目前已有研究证实，肠道菌群（gut microbiota）在引发炎症性慢性疾病的过程中发挥着关键作用。本研究针对正常膳食与高脂膳食条件下，久坐与运动小鼠的肠道完整性/炎症状态及肠道菌群群落展开了探究。 方法 选取36只6周龄的C57BL/6NTac雄性小鼠，分为正常膳食组与高脂膳食组，进行为期12周的膳食干预，并随机划分至运动组与久坐组。干预12周后，处死所有小鼠，取十二指肠/回肠组织固定，针对紧密连接蛋白（occludin）、上皮钙黏蛋白（E-cadherin）以及环氧合酶2（cyclooxygenase-2, COX-2）开展免疫组织化学检测。采用末端限制性片段长度多态性（terminal restriction fragment length polymorphism, TRFLP）分析以及16S rRNA基因扩增子焦磷酸测序技术，对粪便样本中的细菌群落进行检测。 结果 瘦型久坐（LS）小鼠的肠道绒毛组织形态正常，而肥胖型久坐（OS）小鼠的肠道绒毛高度与LS组小鼠相近，但绒毛宽度是LS组的两倍以上。瘦型运动（LX）与肥胖型运动（OX）小鼠的十二指肠及回肠组织形态均未见异常。OS组小鼠的COX-2表达水平最高，其次依次为LS组、LX组与OX组。末端限制性片段长度多态性分析与焦磷酸测序结果显示，梭菌目（Clostridiales）菌群在所有膳食组中均占主导地位。运动组小鼠中可观测到特定的菌型，包括Faecalibacterium prausnitzi、梭菌属（Clostridium spp.）以及别样杆菌属（Allobaculum spp.）。 结论 本研究数据表明，运动对肠道完整性与宿主菌群具有显著调控作用，这提示后续有必要针对肠道内特定菌群与宿主间的互作机制开展更多深入研究。