Fig. 1.

HDF-derived fibrillin microfibril ultrastructure was affected by both broadband UVB and SSR. UVB-irradiated (0.1 J/cm²) fibrillin microfibril periodicities were significantly higher (n = 500 repeats, n = 1500 pooled) than those of control (p < 0.0001, Mann-Whitney U) (Ai; data = mean and SD). Central bead heights were also significantly higher in UVB-irradiated fibrillin microfibrils (n = 100 repeats, n = 300 repeats pooled) than in control (p < 0.0001, Mann-Whitney U) (Aii; data = median, IQR and range). The axial profiles of UVB-irradiated microfibril beads were also significantly higher along the entire central bead axis than those of control (Bonferroni multiple comparison test) (Aiii; data = mean and SD). In order to visualise UVR-induced changes in bead morphology, AFM height maps of control microfibril beads were averaged and subtracted from that of UVB-irradiated microfibril beads. UVB-induced changes in morphology can be observed throughout the bead but primarily along its slopes (~10 nm radius from the peak) (Aiv). Fibrillin microfibril ultrastructure was less affected by SSR (30 J/cm²; B). SSR-irradiated microfibril periodicities were significantly higher than those of control (p < 0.0001, Mann-Whitney U) (Bi; data = mean and SD). Central bead heights were also significantly higher in SSR-irradiated fibrillin microfibrils compared to control (p = 0.0061, Mann-Whitney U) (Bii; data = median, IQR and range). However, axial profiles of SSR-irradiated fibrillin microfibril beads did not differ significantly from those of control (Bonferroni multiple comparison test) (Biii; data = mean and SD). Heat mapped height differences between SSR-irradiated and control show only small changes in bead morphology near central peak and along one of the lateral slopes (Biv).