Fig. 3

(Immuno-)histopathological characterization of perivascular inflammation of controls and individuals with hypertension within white matter. Representative images of perivascular inflammation assessed in glial fibrillary acidic protein (GFAP) stained sections at ×5 magnification of control individuals (a, b) and individuals with hypertension (c, d). a, c Correspond to normal-appearing white matter (NAWM) and b, d to white matter hyperintensity (WMH). The black boxes indicate regions of interest placed on e–h at ×20 magnification to visualize the (close-range) perivascular inflammation. The extent of perivascular inflammation (perivascular astroglia; red arrows) in individuals with hypertension (c, d) was more severe than controls (a, b), with a lower amount of vessels with signs of mild perivascular inflammation (p = 0.017) and more with a severe phenotype (p = 0.002). Individuals with hypertension (g, h) demonstrated more often close-range perivascular inflammation (red asterisks) than the control group (e, f) (p = 0.006). Perivascular inflammation was larger in WMH (b, d) compared to NAWM (a, c) for both groups (p = 0.030). WMH (b, d) showed less vessels with adjoining signs of mild inflammation (p < 0.001), and more vessels with severe perivascular inflammation (p = 0.002) than NAWM (a, c). Close-range perivascular inflammation was present twice as much in WMH (b, d) than NAWM (a, c) (p = 0.017). (Scale bar (a–d) = 500 µm; scale bar (e–h) = 100 µm)