RNA-seq profiling of mammary duct macrophages from virgin, pregnant, lactating and post-weaning mice

Macrophages are diverse immune cells that reside in all tissues. Although macrophages have been implicated in mammary gland function, their diversity has not been fully addressed. By exploiting high-­resolution 3D imaging and flow cytometry, we have identified a unique population of tissue-resident ductal macrophages (DMs) that form a contiguous network between the luminal and basal layers of the entire mammary gland throughout post-­natal development. DMs are long-­lived and constantly survey the epithelium though dendrite movement based on advanced 3D intravital imaging. While they initially originate from embryonic precursors, DMs derive from monocytes as they expand during puberty. Moreover, they undergo proliferation in pregnancy to maintain complete coverage of the epithelium in lactation, where they are poised to phagocytose milk-­producing cells post-­lactation and facilitate remodelling. Interestingly, DMs strongly resemble mammary tumour macrophages and form a network that pervades the tumour epithelium. Thus, the mammary epithelium programs specialised resident macrophages in both physiological and tumorigenic contexts. To explore expression changes as DMs profilerate in pregnancy and lactation, we sorted DMs from the mouse mammary glands of virgin, pregnant, lactating and post-weaning mice and undertook RNA-seq profiling. Results from this data series are shown in Figure 5 of Dawson et al (2020). Three biological replicates were prepared of ductal macrophages from the breast tissue of female mice at four developmental time points: virgin, 16.5 days pregnant, lactating and 1 month post weaning.巨噬细胞是一类分布于全身各组织的异质性免疫细胞。尽管已有研究表明巨噬细胞参与乳腺功能调控，但其异质性尚未被完全阐明。本研究借助高分辨率三维成像与流式细胞术，鉴定出一类独特的组织驻留导管巨噬细胞（ductal macrophages, DMs）：该类细胞在整个出生后发育阶段，于全乳腺的腔面层与基底层之间形成连续的网状结构。导管巨噬细胞寿命较长，借助先进的三维活体成像技术可观察到其通过树突运动持续巡查上皮组织。尽管该类细胞最初起源于胚胎前体细胞，但在青春期扩增阶段则由单核细胞分化而来。此外，其在妊娠阶段发生增殖，以维持泌乳期上皮组织的完全覆盖；泌乳结束后，这类细胞可及时吞噬产乳细胞并促进乳腺组织重塑。有趣的是，导管巨噬细胞与乳腺肿瘤巨噬细胞表型高度相似，且可在肿瘤上皮组织中形成广泛分布的网状结构。由此可见，乳腺上皮可在生理及肿瘤发生两种情境下，调控特异性驻留巨噬细胞的功能。为探究导管巨噬细胞在妊娠与泌乳阶段的表达变化，本研究从未生育、妊娠、泌乳及断奶后小鼠的乳腺组织中分选导管巨噬细胞，并进行RNA-seq转录组分析。本数据集的分析结果已展示于Dawson等人2020年研究的图5中。本数据集设置了4个发育时间点的雌性小鼠乳腺导管巨噬细胞生物学重复样本，每个时间点包含3份生物学重复：未生育期、妊娠16.5天、泌乳期及断奶后1个月。