APLN and Tinnitus: All 19 VS tinnitus samples were examined with immunohistochemistry for KCNQ3, NLRP3, PREX2, GFAP, GPNMB, APLNR, and APLN, as well as S100 (a Schwann cell marker) and CD68 (a macrophage and monocyte marker) (see representative images in Figure 6A).