PECAM1 and tauopathy: CD31 expression level was negatively correlated with the tauopathy marker (r = −0.48, p < 0.0001), with the CD68+/Iba1+ microglia numbers (r = −0.35, p = 0.007) and with CD3+/CD8+ T lymphocytes (r = −0.28, p = 0.03; middle row).