Preclinical characterisation of changes in cardiac function and circulating biomarkers following differential irradiation of thoracic volumes

Figure 1. Schematic overview of the experimental configurations targeting different thoracic volume in the heart, right lung and co-irradiation. Mice were randomized to heart base irradiation (16 Gy), right lung irradiation (10 Gy), or co-irradiation of the heart base (16 Gy) and right lung (10 Gy) (A). Dose volume histograms (DVHs) and mean heart doses (MHD) for each of the targets are shown in (B, C), respectively.

Figure 2. Longitudinal variations in cardiac functional parameters following irradiation of different thoracic volumes at 50 weeks after irradiation (Ejection fraction, EF, (A) Fractional shortening, FS. (B) E/A Ratio, (C) Myocardial Performance Index, (D)]. No significant changes in parameters were observed at 10 weeks after irradiation ( Supplementary Figure S1 ). Data presented are an average of 6 mice per treatment group ± SEM against age-matched control values. Significance values were classified as *p < 0.05, **p < 0.01 and ***p < 0.001.

Figure 3. Histological changes and collagen levels in the irradiated right lung at 10 and 50 weeks following irradiation of different thoracic volumes. The levels of perivascular oedema and pulmonary vessel wall thickness were assessed following H & E staining (A, B, D, E). Fibrosis was assessed by type I collagen staining (C, F). Data presented are an average of 6 mice per treatment group (n = 2 for 50-week control group) ± SEM against age-matched control values. Significance values were classified as *p < 0.05, **p < 0.01 and ***p < 0.001. Scale bar = 50 µm.

Figure 4. Expression of circulating inflammatory cytokines at 10 and 50 weeks following irradiation of different thoracic volumes. Heatmaps of fold changes in cytokine expression compared to age-matched controls are shown at 10 (A) and 50 (B) weeks after irradiation of the heart, heart and lung co-irradiation and the right lung. A principal component analysis (PCA) plot of the samples is shown in (C) Changes in the levels of biomarkers with known cardio-pulmonary functions are shown in (D).

Figure 5. Analysis of volume-specific cytokines and associated biological pathways at 10 and 50 weeks following irradiation of different thoracic volumes. Cytokines showing > 2-fold changes for the different volumes at 10 and 50 weeks (A) with pathway enrichment analysis at the respective timepoints (B, C).