Fig. 3: Crosstalk between principal glomerular cell types and phagocytic activity in mesangial cells.
a Schematic relation of three principal glomerular cell types (MCs, GECs and podocytes). MC mesangial cell, GEC glomerular endothelial cell. b Chord diagrams showing ligand–receptor interactions between MCs, GECs and podocytes identified in mouse and human scRNA-seq datasets. Colours correspond to cell types and ligand/receptor categories, MCs (ligands: orange, receptors: dark red), GECs (ligands: purple, receptors: hot pink) and podocytes (ligands: lime, receptors: blue). The thickness and opacity of the arcs are proportional to the weights of ligand–receptor interactions as used in the NicheNet model. c Ex vivo phagocytosis by mouse glomerular cells. FACS scatter plots show gating of viable glomerular bead+ GFP+ cells isolated from Pdgfrb-EGFP mice. Conjugated pH-sensitive fluorescence is detectable in phagocytosed cells by the mCherry channel. Baseline was determined by incubating cells with beads at 4 °C (left). Notably, 62% of glomerular GFP+ cells are bead+ (phagocytic) when incubated with beads at 37 °C (right). Original flow cytometry plots and gating raw data for all three independent assays are available in the Source data file. d Dot plot showing percentage of bead+ cells in two groups. Percentages (%) of bead-positive cells in triplicate independent assays in 4 °C- and 37 °C-treated groups are presented as dots. Each assay included at least two mice. Error bars are defined as mean values and SD. The two-sided P value of 6.5 × 10−71 was calculated using the proportion test. e Visualization of phagocytosis by EGFP+ cells. In the left image, at 4 °C, fluorescent signal (red) of beads is not detectable. Arrows and arrowheads indicate partially digested glomerular EGFP+ MCs and EGFP+ single cells, respectively. In the right image, at 37 °C, partially digested glomerular EGFP+ MCs co-localize with fluorescent beads (arrows). Bead+ EGFP+ single cells are also visible (arrowheads). Scale bars: 50 µm. f In vitro phagocytosis by human glomerular PDGFRB+ cells. Fluorescent beads (arrows) are detected inside cultured PDGFRB+ (green) human glomerular cells. Hoechst-stained cellular nuclei. Scale bar: 100 µm. g Super-resolution STED microscopy analysis of mouse mesangial accumulation of injected FITC-BSA in vivo. Immunostaining of PDGFRB labelling MCs (violet) and FITC signal of BSA (green) in the mouse glomerulus 1 h after intravenous injection of FITC-BSA. Zoomed mesangium (insets) is indicated by arrows. FITC accumulation is indicated by arrowhead in inset. Glomerular capillary lumens are marked with *. Scale bar: 100 µm.
