Fig 1: An anti-L1CAM antibody (Ab417) inhibits irradiation (IR)- and Dox-induced vascular DNA damage and perivascular fibrosis with L1CAM nuclear localisation, EndMT and cardiac TnT loss.a–e Mice were injected intravenously with control IgG or Ab417 (10 mg/kg) three times a week for 2 weeks and received 16 Gy thoracic IR (No IR n = 7; IR + IgG n = 8; IR + Ab417 n = 8). f–j Mice were injected intravenously with control IgG or Ab417 (10 mg/kg) with or without intraperitoneal Dox injection (4 mg/kg) three times a week for 2 weeks (No Dox n = 7; Dox+IgG n = 8; Dox+Ab417 n = 8). a, f Immunohistochemical detection (left panels) of L1-CT and ?-H2AX in heart tissues 1 week post IR (a) and 2 weeks after Dox treatment (f). The quantified L1-CT+ cells and ?-H2AX+ cells among ECs are shown (magnification, ×200; right panels). Scale bar = 50 µm. Error bars represent mean ± SEM (L1-CT: IR + IgG vs. IR + Ab417 p = 0.0004, ?-H2AX: No IR vs. IR + IgG p = 0.0076; IR + IgG vs. IR + Ab417 p = 0.0017; Dox + IgG vs. Dox+Ab417 p = 0.0003, **** p < 0.0001). b, g Haematoxylin and eosin staining, Masson’s trichrome staining, and immunohistochemical detection of CD31 in heart tissues (left panels); and quantification of arterial wall thickness, perivascular fibrosis area, and microvessel density per field in heart tissues (magnification, ×200; right panels). Scale bar = 100 µm. The arrow in b indicates inflammatory cell infiltration. Error bars represent mean ± SEM (Arterial wall thickness: No IR vs. IR + IgG p < 0.0001; IR + IgG vs. IR + Ab417 p = 0.0159; No Dox vs. Dox p = 0.0009; Dox + IgG vs. Dox + Ab417 p = 0.0117, perivascular fibrosis area: No IR vs. IR + IgG p = 0.0011; IR + IgG vs. IR + Ab417 p = 0.0168; No Dox vs. Dox p = 0.0001; Dox + IgG vs. Dox + Ab417 p = 0.0492, MVD: No IR vs. IR + IgG p = 0.0012; IR + IgG vs. IR + Ab417 p = 0.0184; No Dox vs. Dox p = 0.0093; Dox + IgG vs. Dox + Ab417 p = 0.0378). c, h Serum CRP, E-selectin, and ICAM-1 levels 1 week post IR (c) and 1 week after Dox treatment (h). Error bars represent mean ± SD (CRP: No IR vs. IR + IgG p < 0.0001; IR + IgG vs. IR + Ab417 p = 0.0015; No Dox vs. Dox p = 0.0007; Dox+IgG vs. Dox+Ab417 p = 0.0003, E-selectin: No IR vs. IR + IgG p = 0.0031; IR + IgG vs. IR + Ab417 p = 0.02; No Dox vs. Dox p = 0.0003; Dox+IgG vs. Dox+Ab417 p = 0.0082, ICAM-1: No IR vs. IR + IgG p = 0.0053; IR + IgG vs. IR + Ab417 p = 0.01; No Dox vs. Dox p = 0.0154). d, i Immunofluorescence detection (upper panel) of L1-CT and CD31 in mouse heart tissues 1 week post IR (d) and 2 weeks after Dox treatment (i) (magnification, ×400). Scale bar = 5 µm. Quantification of L1CAM in CD31 nuclei (lower panel). Error bars represent mean ± SEM (No IR vs. IR + IgG p = 0.0012; IR + IgG vs. IR + Ab417 p = 0.0033; No Dox vs. Dox p < 0.0001; Dox IgG vs. Dox+Ab417 p = 0.0004). e, j Immunofluorescence staining of a-SMA and CD31 (scale bar = 10 µm) and of WGA and cTnT (scale bar = 20 µm) in heart tissues 1 week post IR (e) and 2 weeks post Dox treatment (j) (magnification, ×400; upper panels). Quantification of the a-SMA+CD31+ area in the CD31+ area and quantification of the cTnT area per field (lower panels). Error bars represent mean ± SEM (SMA+CD31+ area in the CD31+ area: No IR vs. IR + IgG p < 0.0001; IR + IgG vs. IR + Ab417 p = 0.0011; No Dox vs. Dox p = 0.0013; Dox + IgG vs. Dox + Ab417 p = 0.0103, cTnT area: No IR vs. IR + IgG p = 0.0019; IR + IgG vs. IR + Ab417 p = 0.0107; No Dox vs. Dox p = 0.0126; Dox + IgG vs. Dox + Ab417 p = 0.0494, one-way ANOVA for multiple comparisons). Data are representative of three independent experiments.