Fig. 3

NfL accumulation and fragmentation, and loss of neurofilament colocalization in PD and PDD/DLB. Maximum projections (Z-stacks, Z = 6 μm) of fluorescence stainings of NfL (red) and p-NfM/H (green) together with DAPI (blue) in the parahippocampal gyrus of a representative control (left, control number 10 in Additional file 1: Table S1), PD (middle, PD number 3 in Additional file 1: Table S1) and PDD/DLB (right, here a DLB donor, PDD/DLB number 12 in Additional file 1: Table S1) are shown. a–c show the difference in NfL staining pattern in control, PD and PDD/DLB, respectively. NfL markedly accumulated in neuronal somas and proximal axons in PDD/DLB cases, reflecting the higher NfL immunoreactivity described quantitatively in Fig. 2d. High NfL immunoreactivity was found in neuronal somas showing neurodegenerative morphological features, such as (c) neurons with nuclear fragmentation and swelling (*), and (d) corkscrew (**) and ballooned (***) appearances (panel d shows a zoom-in 3D surface-reconstruction of neurodegenerative neurons). Moreover, (c) NfL accumulation was also identified in a proximal axon showing fragmentation (arrow), closely tighten by a glial cell (#); e shows the zoom-in 3D surface-reconstruction of the white square in c, showing axonal fragmented morphology (arrow) and a glial cell wrapping the degenerating axon (#). f–h show the colocalization (yellow) of NfL and p-NfM/H in control, PD and PDD/DLB, respectively, which was reduced in PD and PDD/DLB. Moreover, accumulation and fragmentation of NfL staining patterns were observed in several axons, where (g) NfL seemed to fragment within a p-NfM/H axon in PD (dashed arrow) and (h) axonal swellings intermitted axonal fragmentations in PDD/DLB (arrows). i Zoom-in 3D surface-reconstruction of the white square in h, clearly showing fragmentation of the NfL-positive axon (arrows). DLB: Dementia with Lewy bodies; NfL: neurofilament light chain; PD: Parkinson’s disease; PDD: Parkinson’s disease dementia; p-NfM/H: phosphorylated neurofilament medium and heavy chain