Background: Human breast milk has a high microRNA (miRNA) content. It remains unknown whether and how milk miRNAs might affect intestinal gene regulation and homeostasis of the developing microbiome after initiation of enteral nutrition. However, this requires that relevant milk miRNA amounts survive gastrointestinal passage, are taken up by cells, and become available to the RNA interference (RNAi) machinery. It seems important to dissect the fate of these miRNAs after oral ingestion and gastrointestinal passage. Objective: Our goal was to analyze the potential transmissibility of milk miRNAs via the gastrointestinal system in neonate humans and a porcine model in vivo to contribute to the discussion whether milk miRNAs could influence gene regulation in neonates and thus might vertically transmit developmental relevant signals. Design: We performed cross-species profiling of miRNAs via deep-sequencing and utilized dietary xenobiotic taxon-specific milk miRNA (xenomiRs) as tracers in human and porcine neonates, followed by functional studies in primary human fetal intestinal epithelial cells (HIEC-6) using Ad5-mediated miRNA-gene transfer. Results: Mammals share many milk miRNAs yet exhibit taxon-specific miRNA fingerprints. We traced bovine-specific miRNAs from formula-nutrition in human preterm stool and 9 days after onset of enteral feeding in intestinal cells of preterm piglets. Thereafter, several xenomiRs accumulated in the intestinal cells. Moreover, few hours after introducing enteral feeding in preterm piglets with supplemented reporter miRNAs (cel-miR-39-5p/-3p), we observed their enrichment in blood serum and in AGO2-immunocomplexes from intestinal biopsies. Conclusions: Milk-derived miRNAs survived gastrointestinal passage in human and porcine neonates. Bovine-specific miRNAs accumulated in intestinal cells of preterm piglets after enteral feeding with bovine colostrum/formula. In piglets, colostrum supplementation with cel-miR-39-5p/-3p resulted in increased blood levels of cel-miR-39-3p and argonaute RISC catalytic component 2 (AGO2) loading in intestinal cells. This suggests the possibility of vertical transmission of miRNA signaling from milk through the neonatal digestive tract.

中文翻译：

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使用 xenomiRs 作为示踪剂揭示新生儿的胃肠道、肠上皮细胞摄取和乳汁 miRNAs 的 AGO2 加载

背景：人类母乳中的 microRNA (miRNA) 含量很高。在开始肠内营养后，牛奶 miRNA 是否以及如何影响肠道基因调控和发育中的微生物组的稳态仍然未知。然而，这需要相关的牛奶 miRNA 量在胃肠道中存活下来，被细胞吸收，并可用于 RNA 干扰 (RNAi) 机制。剖析这些 miRNA 在口服摄入和胃肠道通过后的命运似乎很重要。目标：我们的目标是分析乳汁 miRNA 通过新生儿胃肠道系统和体内猪模型的潜在传递能力，以促进讨论乳汁 miRNA 是否可以影响新生儿的基因调控，从而可能垂直传递发育相关信号。设计：我们通过深度测序对 miRNA 进行了跨物种分析，并利用膳食异种生物分类群特异性乳 miRNA (xenomiRs) 作为人类和猪新生儿的示踪剂，然后使用 Ad5 对原代人胎儿肠上皮细胞 (HIEC-6) 进行功能研究-介导的 miRNA 基因转移。结果：哺乳动物共享许多乳汁 miRNA，但表现出分类单元特异性 miRNA 指纹。我们从人类早产粪便中的配方营养和早产仔猪肠内喂养开始后 9 天的肠道细胞中追踪了牛特异性 miRNA。此后，一些 xenomiRs 在肠细胞中积累。此外，在用补充的报告基因 miRNA (cel-miR-39-5p/-3p) 对早产仔猪进行肠内喂养几小时后，我们观察到它们在血清和来自肠道活检的 AGO2 免疫复合物中的富集。结论：乳汁来源的 miRNA 在人类和猪新生儿的胃肠道中存活下来。在用牛初乳/配方奶肠内喂养后，早产仔猪的肠道细胞中积累了牛特异性 miRNA。在仔猪中，添加 cel-miR-39-5p/-3p 的初乳导致肠道细胞中 cel-miR-39-3p 和 argonaute RISC 催化组分 2 (AGO2) 的血液水平升高。这表明 miRNA 信号通过新生儿消化道垂直传播的可能性。初乳补充 cel-miR-39-5p/-3p 导致 cel-miR-39-3p 和肠细胞中 argonaute RISC 催化组分 2 (AGO2) 的血液水平升高。这表明 miRNA 信号通过新生儿消化道垂直传播的可能性。初乳补充 cel-miR-39-5p/-3p 导致 cel-miR-39-3p 和肠细胞中 argonaute RISC 催化组分 2 (AGO2) 的血液水平升高。这表明 miRNA 信号通过新生儿消化道垂直传播的可能性。