Fig. 6: Redistribution of acinar deposited NPs can be attributed to phagocytosis and migration of TRMs.

a Lung intravital microscopy (IVM) revealed the dynamic movement of PKH labeled macrophages toward epithelial-deposited NPs by patrolling the alveolar epithelial surface. n = 3, VAAD_0 h lungs, independent biological replicates. Scale bar: 20 µm. b Relative frequencies of average tracking velocities of PKH-labeled macrophages in vivo imaged by IVM. n = 3 VAAD_0 h, n = 4 ITLI_24 h, independent biological replicates. c Trajectory plot outlines relative patrolling behaviors of individual PKH-labeled macrophages from 3 VAAD_0 h lung imaged by IVM (Start points of the migration tracks set to 0,0). d, e Fractions of NP⁺ cells in PKH⁺ cells and fractions of CD11b⁺ or SiglecF⁺ in NP⁺PKH⁺ cells in normal and lavaged 24 h ITLI lungs. n = 3 (lavaged) or 5 (normal), independent biological replicates. f Ex vivo lung living microscopy showed the migration of GFP⁺NP⁺ macrophages in the PCLS (n = 4). Scale bar: 20 µm and 10 µm (ROI). g Exemplary cell population analysis of GFP⁺NP⁺ macrophages and (h, i) Fractions of NP⁺ cells in GFP⁺ cells and fractions of CD11b⁺ or SiglecF⁺ in NP⁺GFP⁺ cells in normal and lavaged lungs. n = 3 (lavaged) or 4 (normal), independent biological replicates. Data are presented as mean ± SD, calculated using one-tailed unpaired t test (d, h) and multiple two-tailed unpaired t test with Holm-Šídák correction (e, i). j Macroscale and microscale views of GFP⁺ macrophages/monocytes and NP deposition in an 4 h ITLI lung lobe (n = 3). White arrowheads indicate merged signals of GFP and NPs. Scale bars: 1000 µm (overview), 200 µm (ROI1), and 100 µm (ROI2). k Co-expression/staining of GFP, PKH dye, and NP⁺ BAL cells obtained from 24 h ITLI mac-green mice (n = 3). White arrowheads and arrows, yellow, and blue arrows indicate triple positive cells, double positive cells (PKH⁺ and GFP⁺), and GFP⁺ cells, respectively. Scale bar: 20 µm. Source data are provided as a Source Data file.