Xenobiotic tracers uncover the neonatal gastrointestinal passage, cellular uptake and Ago2 loading of milk miRNAs in neonates

Whether milk microRNAs might vertically transmit signals for neonatal development or not remains an outstanding question with clinical implications. Deep-sequencing revealed that mammals have in common a significant number of milk miRNAs yet exhibit taxon-specific milk miRNA fingerprints. We could trace intact bovine-specific microRNAs from formula-nutrition in human preterm stool and 9 days after the onset of enteral feeding in intestinal cells of a preterm piglet model. Few hours after the introduction of enteral feeding with reporter microRNA-supplementation (cel-miR-39-5p/-3p), we observed enrichment of this xenobiotic microRNA in blood serum and in Ago2-immunocomplexes from intestinal biopsies. This points to a relevance of milk microRNA signals. We performed Adenovirus type 5-based microRNA-gene transfer into human primary intestinal epithelial cells and examined predicted bta-miRs targets on the protein and transcriptome levels. Results suggest that milk microRNAs could influence the expression of human genes in intestinal epithelia of neonates under special conditions in vitro.

乳汁微RNA（microRNAs, miRNAs）是否能够通过垂直传递信号参与新生儿发育调控，仍是一个兼具重要临床意义的前沿未解科学问题。深度测序（deep-sequencing）研究表明，不同哺乳动物共享大量乳汁miRNA，同时又各自具备类群特异性的乳汁miRNA特征谱。我们可在早产儿粪便中溯源到配方营养来源的完整牛特异性微RNA，并在早产仔猪模型的肠上皮细胞中，于肠内营养（enteral feeding）启动9天后检测到这类分子。当通过肠内营养补充报告型微RNA（cel-miR-39-5p/-3p）后的数小时内，我们在血清以及肠活检样本的Ago2免疫复合物（Ago2-immunocomplexes）中观察到该外源性微RNA（xenobiotic microRNA）出现显著富集。这一发现证实了乳汁微RNA信号具有生物学相关性。我们采用5型腺病毒（Adenovirus type 5）介导的微RNA基因转染体系处理人原代肠上皮细胞，并在蛋白质组与转录组层面验证了预测得到的牛源微RNA（bta-miRs）靶标。实验结果显示，在体外特定培养条件下，乳汁微RNA可调控新生儿肠上皮细胞内人类基因的表达。