Fig. 8: Fibroblast EGFR deficiency led to less fibroblast proliferation in response to unilateral ureteral obstruction (UUO).

a–d snRNAseq analysis indicated characteristics of fibroblast and myofibroblast subclusters following unilateral ureteral obstruction (UUO). The R package CellChat was used, and CellChatDB is the built-in database in CellChat without a separate version. a Gene Ontology (GO) Biological Process analysis for fibroblast subclusters based on the top marker genes for each cluster suggested that Fib1 cluster was associated with kidney development, MF3 cluster with immune cell activation and differentiation, and MF4 cluster with fibroblast proliferation. b Trajectory analysis showed a continuous change in RNA profile in WT fibroblasts from day 1 to day 3 after UUO injury. c Pseudotime analysis was performed to infer paths of cell-state transitions within the fibroblast clusters. d In combination with GO terms, Fib2/MF2 dominated the first day in the UUO model, probably due to the activation and differentiation of local fibroblast cells in the kidney. Fib1/MF3 may arise from the transdifferentiation of renal cells after injury or some cells from migration, and these fibroblast subclusters were more inclined to activate immune cells and promote differentiation and to participate in cross-talk with immune cells. MF4 was associated with fibroblast proliferation on tday three in the UUO model. e FibEGFR−/− had less kidney fibrosis compared to WT mice at day 3 after UUO. n = 4. Scale bar = 50 μm. Both the percentage of mCherry+ fibroblasts/myofibroblasts in total kidney cells (n = 7) (f) and the proliferation rate of fibroblasts/myofibroblasts (EdU+ mCherry+ double positive cells) (n = 4) (g) were markedly lower in FibEGFR−/− mice than WT mice. h Immunofluorescent staining showed fewer kidney PCNA+ α-SMA+ double positive cells (red arrows, proliferating fibroblasts/myofibroblasts) in FibEGFR−/− mice compared to WT mice. n = 5. Of note, PCNA+ positive cells were also observed in tubular cells in both WT and FibEGFR−/− mice. Scale bar = 50 μm. Data are means ± SEM, **P < 0.01, **P < 0.001, analyzed using two tailed Student’s t test for all.