TJP1 and Alzheimer disease: In fact, the structure and functions of the tight junctions are strongly affected in the cerebrovascular cells of AD patients.92 In an animal model of AD, a cholesterol-enriched diet down-regulated the expression of the occluding and ZO-1, which was strongly correlated with the elevated level of the BBB leakage.93In vitro, treatment of primary rat CECs with Aβ1–42 for 3 days altered expression of occluding and claudin-1, caused relocation of plasma membrane subunits of claudin-5 and ZO-2 to the cytoplasm.