Abstract: Objective　To investigate the effect of miRNA on lung physiology in infants and toddlers by measuring the microRNAs（miRNAs） levels in the bronchoalveolar lavage fluid（BALF） cells. Methods　A total 13 infants and toddlers with airway foreign body removed within 24 hours were enrolled. The BALF cells of 4 children were taken and levels of miRNAs were measured by miRNA microarray and verified by q-PCR. Results　Over 800 miRNAs expression were found among BALF cells. Among the most abundant 100 miRNA，only one pre-miRNA，miR-6800 with 82 bases，was found，and the orthers were mature miRNA. Moreover，the let-7 family was very rich in BALF cells. In the most abundant 100 miRNAs，there were 6 miRNAs of let-7 family，6 miRNAs of miR-17 family，5 of miR-34/449 family，4 of miR-320 family，3 of miR-378 and 2 of miR-146. The miRNA of miR-34/449 family verified by q-PCR showed similar results to miRNA microarray. Conclusion　The data show that there are a large number of miRNA expressions in lung of infants and toddlers，including let-7，miR-17，miR-34/449，miR-146 families，and so on，which suggests that miRNAs participate in not only the normal metabolism of lung cell，but also the maintenance of physiological functions such as immune regulation.

Key words: lung, microRNA, bronchoalveolar lavage fluid, physiology, infant

摘要： 目的　通过检测婴幼儿支气管肺泡灌洗液（BALF）细胞中的microRNA（miRNA）水平，探讨miRNA在婴幼儿肺部的生理功能。方法　收集2017年6月至9月浙江大学医学院附属儿童医院13例支气管异物患儿标本，其异物均在24 h内取出，将其中4例患儿BALF细胞送miRNAs芯片检测，并对部分miRNA进行实时荧光定量聚合酶链反应（qPCR）验证。 结果　miRNA芯片发现BALF细胞中有800多种miRNA表达。在最丰富的100个miRNA中，除miR-6800为82个碱基的发卡形状的pre-miRNA外，其余均为成熟miRNA。分析BALF细胞中表达丰富的100种miRNA，发现let-7家族非常丰富，在最丰富100个miRNA中有6个let-7家族、6个miR-17家族、5个miR-34/449家族、4个miR-320家族、3个miR-378和2个miR-146家族。miR-34/449家族miRNA的PCR结果与miRNA芯片类似。结论　研究发现婴幼儿BALF大量miRNA表达，包括let-7、miR-17、miR-34/449、和miR-146家族等，说明miRNA不仅参与正常肺部细胞新陈代谢，还参与免疫调控等生理功能的维持。

关键词: 肺, microRNA, 支气管肺泡灌洗液, 生理, 婴幼儿