Fig. 6: Senescent macrophages induce ferroptosis of muscle cells through disruption of local iron homeostasis in the quadriceps during OA progression.
a, Scheme of proteomic sequencing. b,c, PCA (b) and the heatmap (c) (n = 4). d, The levels of free Fe2+ and Fe3+ in quadriceps of patients with OA and controls (n = 10) and of mice at S12 and D12 (n = 10). e, The top 15 enriched pathways of DEPs. f, Representative enriched sets of DEGs. g,h, Representative TEM images of quadriceps muscles from patients with OA and control subjects (n = 42 control section, from 5 individuals; n = 55 OA section, from 5 individuals) (g) and from mice at S12 and D12 (n = 10 sham, n = 9 DMM) (h). i, Representative flow cytometry profiles of mitochondria and MFI of indicated dyes staining in mitochondria (n = 4 sham, n = 5 DMM). j, Representative images and statistical charts of SDH staining (n = 6 sham, n = 5 DMM). k,l, LPO products level (n = 5) (k) and blots and quantitative results (n = 3) (l). m, Scheme of stimulating myotubes or C2C12 cells with conditioned medium (CM) from macrophages of mice at S12 and D12. n–p, Representative MyHC immunofluorescence staining images and mean diameter (n = 5) (n), blots and quantitative results (n = 3) (o), and MFI of MitoTracker and MitoSOX (n = 5) (p). q,r, MFI of C11 BODIPY 581/591 staining (q) and Helix NP staining (r, n = 5). s,t, Measurement of MFI for the indicated dyes (s) and quantification of LPO levels in indicated mice (n = 5) (t). u, Graphic abstract. Data are presented as mean ± s.e.m. unless otherwise noted; all statistical tests were two-sided unless otherwise noted; and n represents biological replicates unless otherwise noted. Student’s t-test (d (ferric iron of patients), d (free ferrous iron of mice), i–l,n–p,s,t). Mann–Whitney U-test (d (free ferrous iron of patients), d (ferric iron of mice), g,h (mean area)). One-way ANOVA with Bonferroni test (r). One-way ANOVA with Tamhane’s T2 test (q). Two-way ANOVA with Bonferroni test (h (distribution)). Median (25% IQR, 75% IQR; d (free ferrous iron of patients), d (ferric iron of mice), g,h (mean area)). RBCs, red blood cells.
