Deciphering the phenotypes of mammary gland macrophage subsets during lactation

Abstract

The mammary gland is a dynamic tissue that undergoes extensive remodeling in preparation for pregnancy and lactation. Its function is also affected by pregnancy complications such as gestational diabetes mellitus (GDM). However, it is unclear how these changes affect the composition and functions of its cells. With the recent interest in the characterization of tissue-resident macrophages (TRMs) in the mammary gland, we conducted a comprehensive phenotypic analysis of macrophages (MØs) in the lactating mammary gland of mice at post-parturition day 7, 14, and 21 (P7, P14, P21) via high dimension flow cytometry and found ductal MØs as the dominant immune cell type in P14 mice. We also identified potential markers for improved characterization of different mammary MØ subsets, and observed elevated levels of ductal MØs in mammary glands of mice models induced with GDM versus healthy controls. This suggests the crucial role of ductal MØs in lactation as well as in diseased states like GDM. Taken together, this data provides further insight towards the knowledge of mammary TRM characterization and the discovery of potential novel TRM surface markers as therapeutic targets for GDM and beyond.