Expression of tight junction protein claudin - 5 , in cerebral microvessels (frontal cortex) from Apo E−/−
mice exposed to mixed vehicular emission or filtered air. Double immunofluorescence of claudin-5 (green fluorescence: A, D) and vonWillebrand factor (vWF) (red fluorescence: B, E) in cerebral microvessels (frontal cortex) from Apo E−/− mice exposed to 100 μgPM/m3 of mixed vehicular emission (MVE: A – C) or filtered air controls (FA: D - F) for 6 hr/day, for 30 days. Colocalized expression of occludin and vWF in microvascular endothelial cells is shown in panels C and F, indicated by yellow fluorescence. Colocalization was determined by quantifying total fluorescence of overlayed signals from minimum of three slides, two sections each, three regions from each section (n = 4–5 per group), which is represented by the graph shown in panel G. Arrows indicate expression of claudin-5 (D) and endothelial-cell specific claudin-5 expression (F) in the cerebral microvasculature of FA animals, which is measurably decreased in the microvessels from MVE-exposed animals (A and C, respectively). Scale bar = 10 μm; 100× magnification. Control slides with no primary antibody were also done (not shown) to confirm specific binding. *p < 0.050 compared to FA control.