Expression of TJ proteins in HBMECs and microvessels from autopsied brains of seronegative controls and HIV-1–infected humans. (A) All MV samples stained positive for claudin-5. MVs from seronegative control donors (eg, patients N1 and N2) show prominent and continuous strands of tight junction (TJ, arrows); TJ strands in MVs from HIV-1–seropositive patients without HIVE (eg, P1 and P2), and HAD HIVE patients (eg, HAD2 and HAD5) were fewer and had more gaps (arrowheads). Patient HAD5 shows very few TJ strands. (B) Computer-assisted semiquantitative analyses of all MV samples show a significant decrease in claudin-5 expression in MVs from HAD patients, compared with MVs from HIV-1–seropositive patients without HIVE (HIV-POS), or seronegative controls (HIV-NEG). MVs from HIV-1–seropositive patients without HIVE also showed a small (nonstatistically significant) decrease in claudin-5 expression compared with seronegative controls. (C) Double immunostaining of MVs for human CD163 (green) and VWF (red) showed that the isolated MVs did not have macrophage contamination. (D-F) Exposure of HBMECs to HIV-1 (MOI: 0.01) for 24 hours decreased the expression of claudin-5, ZO-1 and ZO-2. Densitometry analysis showed that FLUD significantly diminished HIV-induced down-regulation of claudin-5 (E) and ZO-1 (F). Original magnification of images in panels A and C: ×400.