Fig. 4

Immunohistochemical analysis of neuronal S100A9 in the PD substantia nigra and frontal lobe tissues (five cases studied). a–c Sequential immunohistochemistry of the representative PD substantia nigra region with S100A9, CD68, and α-syn antibodies, respectively. d Superposition of the corresponding images from a–c shown in pseudo-colors: S100A9 immunostaining is shown in yellow, α-syn in blue, and CD68 in magenta. e–g Enlarged images of the sequential immunohistochemistry of the representative substantia nigra region collected from another PD patient and conducted by using S100A9, CD68, and α-syn antibodies, respectively. Black arrows mark the accumulation of α-syn and S100A9 in small granules. h Superposition of the corresponding images from e–g shown in pseudo-colors: color coding as in d. i, j Sequential immunohistochemistry of the representative PD frontal lobe tissues with S100A9 and CD68 antibodies, respectively. k Superposition of the corresponding images from i, j shown in pseudo-colors: color coding as in d. l Counts of S100A9-immunopositive neuronal cells in controls are shown by black bars and in PD patients by red bars; frontal lobe is labeled by FL and substantia nigra by SN. Percentage of the co-localization of S100A9 and α-syn within neuronal cells and Lewy bodies in the substantia nigra shown by blue bars. p ≤ 0.05 is indicated by *. Scale bars are 100 μm in a–d and 50 μm in e–k