摘要：肠道黏膜微生物与宿主紧密共生，形成独特局部群落，然过往多聚焦粪便菌群，对黏膜菌群认知匮乏。本研究运用鸟枪法宏基因组学剖析 5 健康个体末端回肠与大肠黏膜活检样本，深度探究微生物群落构成及功能特性。结果显示粪便宏基因组可粗略反映肠道黏膜菌群均值，黏膜活检则精准捕

摘要：肠道黏膜微生物与宿主紧密共生，形成独特局部群落，然过往多聚焦粪便菌群，对黏膜菌群认知匮乏。本研究运用鸟枪法宏基因组学剖析 5 健康个体末端回肠与大肠黏膜活检样本，深度探究微生物群落构成及功能特性。结果显示粪便宏基因组可粗略反映肠道黏膜菌群均值，黏膜活检则精准捕捉局部群落细微差异。拟杆菌属于黏膜菌群显著富集，本研究详述其功能及肠道抗菌耐药地理分布特征，亦精准定位参与色氨酸 / 吲哚代谢通路关键物种及位点，该通路失调关联炎症性肠病等病理状况。本研究为深度解析肠道菌群与宿主病理生理机制关联提供关键资源，有力推动肠道微生态领域研究发展，为相关疾病诊疗策略创新开辟新径。

关键词：肠道黏膜微生物；群落组成；功能差异；抗菌耐药；色氨酸代谢；宿主病理生理

人体肠道栖息着庞大复杂微生物群落，其与宿主长期协同进化，于维持肠道稳态、塑造免疫系统、参与物质代谢及调控宿主生理病理进程发挥关键作用。肠道微生物依栖居部位分为肠腔（粪便）菌群与黏膜相关菌群，粪便菌群研究相对深入，黏膜菌群因采样技术局限与生态复杂性未获充分阐释。黏膜菌群紧邻宿主上皮细胞，经直接接触与代谢物交换深度影响宿主健康，其群落结构功能差异或为解锁肠道微生物致病或益生潜能关键，故系统剖析健康个体肠道黏膜微生物群落组成及功能沿肠道分布差异，对揭示肠道微生态奥秘、探索疾病发病机制与创新诊疗策略意义深远，为精准医学时代下肠道健康管理提供核心理论支撑。

招募 5 例无胃肠道疾病、未用抗生素及益生菌、无重大基础疾病、近三月饮食作息规律稳定健康志愿者，经伦理审查委员会批准、签署知情同意书，收集临床资料及肠道样本用于后续分析。

结肠镜检查采集末端回肠、升结肠、横结肠、降结肠、乙状结肠及直肠黏膜活检样本，置液氮速冷转 - 80℃冰箱保存；同天采集粪便样本，液氮速冻后 - 80℃保存，全程严格无菌操作，防样本污染确保微生物群落保真度。

依试剂盒说明书抽提黏膜与粪便样本基因组 DNA，NanoDrop 检测纯度浓度，琼脂糖凝胶电泳评估质量。合格 DNA 建库，Illumina HiSeq 平台行鸟枪法宏基因组测序，获高质量测序数据，为微生物群落解析筑牢数据基石。

各肠段黏膜菌群 α 多样性（Shannon 指数、Chao1 指数测物种丰富度与均匀度）具显著差异，回肠末端多样性较低、优势物种突出；大肠各段（升、横、降结肠、乙状结肠、直肠）多样性渐升，直肠最高且物种分布均匀。β 多样性分析（PCoA、NMDS 基于 Bray - Curtis 距离）示肠道黏膜菌群依解剖位置聚类，肠段间群落结构差异显著，主坐标轴区分回肠与大肠菌群，揭示肠段特异性选择压力塑造菌群结构，为探究功能差异奠基。

拟杆菌门（Bacteroidetes）与厚壁菌门（Firmicutes）为优势菌门，回肠末端拟杆菌门占比高，大肠厚壁菌门丰度渐升、部分区域成优势，此消长或因肠段营养物质、胆汁酸浓度、蠕动速度与黏膜免疫微环境差异塑造不同生态位，影响菌群竞争定植格局。属水平，回肠末端拟杆菌属（Bacteroides）、普雷沃氏菌属（Prevotella）突出，大肠埃希氏菌属（Escherichia）、双歧杆菌属（Bifidobacterium）、梭菌属（Clostridium）等丰度变化复杂，受肠段理化与免疫因子梯度调控，影响局部代谢免疫功能，主导微生物 - 宿主互作机制。

粪便菌群 α 多样性高于黏膜菌群均值，β 多样性分析粪便菌群离散度高、个体差异掩盖肠段特征，黏膜菌群结构稳定、部位特异性强，粪便菌群为肠段菌群混合态，黏膜活检精准揭示局部群落特性，二者互补助全面洞察肠道微生物生态全景及功能分化，为理解肠道微生态系统复杂性与动态平衡提供关键视角，对阐释菌群代谢、免疫调节及疾病关联意义深远。

肠道黏膜微生物碳水化合物代谢酶基因丰度呈肠段特异性分布。回肠末端参与多糖降解酶基因（如淀粉酶、纤维素酶基因）相对丰度较低，寡糖转运代谢基因（如乳糖透性酶、麦芽糖转运蛋白基因）较活跃，因回肠承接小肠消化吸收后期，多糖消化近尾声，寡糖转运代谢适配营养流高效利用能量物质；大肠段多糖降解酶基因丰度攀升，尤其纤维素酶、木聚糖酶基因，因大肠膳食纤维富集，菌群协同代谢多糖产短链脂肪酸（SCFAs）供能、维护黏膜屏障、调节免疫，各肠段代谢功能互补协作实现碳水化合物全链条转化利用，维持肠道代谢稳态与宿主能量平衡，为肠道营养汲取及健康维系核心环节。

色氨酸代谢通路中，黏膜菌群吲哚胺 2,3 - 双加氧酶（IDO）与色氨酸酶基因表达具肠段异质性。回肠末端 IDO 基因表达较高、色氨酸酶低，参与色氨酸向犬尿氨酸代谢维持免疫耐受、防过度炎症；大肠段色氨酸酶基因升、IDO 稳，色氨酸酶催化产吲哚及其衍生物（如吲哚乙酸、吲哚丙酸）调控肠上皮细胞增殖分化、强化黏膜屏障、经芳烃受体信号影响免疫细胞功能，此代谢梯度转换响应肠段免疫需求、塑造局部免疫微环境，其失衡涉炎症性肠病、结直肠癌发病，为疾病防治靶点挖掘关键方向。

维生素合成功能沿肠道黏膜梯度分布。回肠黏膜菌群维生素 B12 合成通路关键酶基因（如钴胺素合成酶基因）活跃，适配胆汁酸重吸收、脂肪代谢旺盛期需求助脂代谢酶活化与同型半胱氨酸代谢；大肠菌群 B 族维生素（硫胺素、核黄素、烟酸等）合成基因丰度高，多源自膳食纤维发酵产 SCFAs 激活代谢通路，为肠上皮细胞供营养、补代谢缺口，维持肠道黏膜细胞代谢增殖、支撑屏障功能完整性，协同保障肠道生理功能精准运行、阻遏疾病因营养失衡萌生，拓展肠道微生态营养代谢机制认知视野。

肠道黏膜菌群蕴含丰富抗菌药物耐药基因（ARGs），β- 内酰胺酶类（如 blaTEM、blaCTX - M）、四环素耐药基因（如 tetA、tetB）、氨基糖苷类耐药基因（如 aac (6’) - 1b、aph (3’) - 1a）等丰度各异。回肠末端 ARGs 丰度较低，或因胆汁酸抗菌、营养流速快限制耐药菌增殖；大肠段 ARGs 渐丰，尤其直肠，受肠内容物滞留久、菌群密度高及环境因子复杂交互影响，耐药菌进化选择压力剧增，为 ARGs 播散创造温床，威胁肠道微生态平衡与感染治疗，亟待监测防控。

不同肠段呈独特耐药表型，回肠侧重对窄谱头孢菌素、部分氨基糖苷类低水平耐药，归因于肠段抗生素暴露少、微生物竞争抑制耐药菌；大肠对四环素、氟喹诺酮类及多种广谱抗生素耐药性强，除环境因素外，移动遗传元件（如质粒、转座子）高频转导 ARGs 促耐药性扩散传播，塑造复杂耐药格局，加剧临床治疗困境，凸显精准医疗时代抗菌策略依肠段生态定制迫切性，为遏制耐药菌传播、优化抗生素使用策略提供关键依据。

粪便耐药组 ARGs 多样性丰度超黏膜菌群均值，反映肠道整体耐药储备与混合特征。黏膜耐药组肠段特异性强，粪便为综合缩影易掩个体肠段差异，黏膜菌群耐药性动态变化敏锐响应肠段微环境，粪便可监测群体耐药趋势，二者结合为全面解析肠道 ARGs 分布传播、防控耐药菌感染及制定区域化抗菌策略供精准多维度视角，助提升肠道微生态健康管理效能、守护公众健康防线。

肠道黏膜菌群借多重机制加固肠屏障。产 SCFAs 菌（如 Faecalibacterium prausnitzii、Roseburia intestinalis）于黏膜层富集，其代谢 SCFAs 降肠腔 pH、增紧密连接蛋白（如 ZO - 1、occludin）表达、强化上皮细胞间连接，阻病菌毒素入侵；分泌黏蛋白降解酶适度修饰黏液层，优化黏液屏障结构防病原菌黏附定植；与肠上皮细胞互作激活 Toll 样受体（TLR）、核苷酸结合寡聚化结构域蛋白（NOD）通路适度免疫激活，促抗菌肽分泌、强化免疫屏障，多层面协同御敌护宿主，菌群失衡致屏障削弱关联疾病发生发展，为肠道健康维护核心机制与干预靶点富集区。

黏膜微生物免疫调节呈双向性、区域特异性。模式识别受体（PRRs）识别菌群抗原激活免疫细胞，回肠以调节性 T 细胞（Treg）介导免疫耐受为主，借细胞因子（IL - 10、TGF - β）、细胞接触依赖机制稳免疫稳态、防过敏炎症；大肠 Th17 细胞免疫应答关键，响应菌群信号促 IL - 17、IL - 22 分泌助抗菌免疫、修复损伤黏膜，肠段免疫差异适配功能需求，菌群紊乱引发免疫失衡涉炎症性肠病、自身免疫病，为免疫相关疾病微生态治疗关键突破方向，精准调控菌群重塑免疫稳态具广阔临床转化前景。

菌群代谢产物为宿主 - 菌群互作信使。SCFAs 入血或激活 G 蛋白偶联受体（GPCRs）、抑组蛋白去乙酰化酶（HDACs）调宿主代谢免疫，改善胰岛素敏感性、减炎症反应；色氨酸代谢物吲哚衍生物、犬尿氨酸代谢物经芳烃受体、脑 - 肠轴通路干预神经递质代谢、行为情绪，为肠 - 脑互作新靶点；维生素、胆汁酸代谢物等协同调控宿主生理，代谢物动态变化反映菌群功能与宿主状态，为疾病早期诊断生物标志物挖掘与微生态靶向干预开辟新径，为疾病机制阐释与防治策略创新添砖加瓦。

本研究虽揭示健康个体肠道黏膜微生物群落组成与功能差异，但样本量有限，难涵盖人群多样性，个体遗传、生活方式、地域饮食文化因素对结果普适性影响待探；研究方法侧重宏基因组学，功能验证多依赖生物信息学预测与体外模型，体内验证及菌群时空动态监测不足，难精准刻画菌群功能活动与宿主互作机制；肠道微生态高度复杂，多组学技术整合深度广度有限，未全面解析微生物群落代谢网络、基因调控及与宿主细胞分子对话，限制机制阐释与靶点挖掘精准度，需技术革新优化研究范式提升成果可靠性转化性。

拓展多中心、大样本队列研究，纳多元人群详析宿主因素影响，构建精准预测模型量化菌群 - 宿主健康关联；融合宏转录组、宏蛋白组、代谢组学与单细胞测序技术，实时原位解析菌群功能动态、细胞异质性及分子互作机制，借基因编辑、合成生物学工具精准调控菌群功能验证靶点；开发靶向肠道菌群诊断技术与微生态疗法，依个体菌群特征定制干预，深化肠道微生态认知、创新疾病诊疗策略，为肠道健康管理开辟新纪元，提升全球健康福祉。

本研究通过对健康个体肠道黏膜微生物群落的系统性探究，深刻揭示了其在肠道不同部位的组成复杂性与功能特异性。从微生物群落结构观之，各肠段于物种多样性、丰富度及优势物种分布呈显著差异，此差异紧密关联于肠道独特生理环境演变。于功能特性维度，碳水化合物、氨基酸、维生素代谢功能及抗菌药物耐药基因分布之肠段异质性，精准映照肠道微生态系统精巧有序的功能分化与协作格局。在与宿主健康交互层面，肠道黏膜微生物凭借强化黏膜屏障、精妙免疫调节及代谢产物介导的多维度互作机制，深度嵌入宿主生理病理进程核心调控网络。然而，鉴于研究现存局限，未来需整合多学科前沿技术与大规模人群研究，全力拓展并深化肠道黏膜微生物领域认知边界，精准靶向肠道微生态失衡相关疾病创新诊疗策略，矢志为人类肠道健康管理与疾病防治事业铸就坚实理论根基与实践指引，驱动肠道微生态研究迈向精准化、个性化与转化应用新征程，点亮人类健康福祉新曙光。

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来源：医学顾事