FIGURE 1 from LYVE-1–expressing Macrophages Modulate the Hyaluronan-containing Extracellular Matrix in the Mammary Stroma and Contribute to Mammary Tumor Growth

LYVE-1⁺ macrophages localize near stromal HA in the nulliparous mouse mammary gland and are associated with ECM regulation. A, Representative images from mammary gland capsular regions of 5-week Csf1rfl/fl (top) and Lyve1CreCsf1rfl/fl (bottom) mice immunostained for LYVE-1 (green), CD206 (red), HABP (magenta), and DAPI (blue; n = 4 per genotype). B, Representative images from mammary gland stroma regions of 5-week Csf1rfl/fl (top) and Lyve1CreCsf1rfl/fl (bottom) mice immunostained for LYVE-1 (green), F4/80 (red), HABP (magenta), and DAPI (blue; n = 4 per genotype). C, Mammary glands from 5-week Csf1rfl/fl (gray) and Lyve1CreCsf1rfl/fl (blue) female mice were assessed for CD45⁻LYVE-1⁺ frequency by flow cytometry. D, Mammary glands from 5-week Csf1rfl/fl (gray) and Lyve1CreCsf1rfl/fl (blue) female mice were assessed for CD45⁺F4/80⁺CD11b⁺ LYVE-1⁺ macrophage count by flow cytometry. Fold change of Lyve1 (E), Hyal1, and Hyal2 (F) RNA expression from 15-week Csf1rfl/fl (gray) and Lyve1CreCsf1rfl/fl (blue) female mice. G, MFI of HABP in mammary glands assessing CD45⁺F4/80⁺CD11b⁺LYVE-1⁻ and CD45⁺F4/80⁺CD11b⁺LYVE-1⁺ macrophages. H, Mammary gland from 5-week and 15-week Csf1rfl/fl (gray) and Lyve1CreCsf1rfl/fl (blue) female mice assessed for HA by ELISA and normalized by weight. I, Female mammary glands assessed by ECM qRT-PCR array with differentially downregulated genes associated with biological process Gene Ontology (GO) terms (black) and molecular function GO terms (white; n = 3 per genotype). *, P < 0.05; **, P < 0.01; ****, P < 0.0001, using Student t test. Scale bars, 100 µm. Each dot represents one mouse.