Our findings support the assumptions that HIV infection can initiate damage to the CNS, and that the CNS disorders result from the indirect effects of viral infection. Novel molecules have been identified which are expressed by the specialized BBB endothelial cells. One of these, named MBEC1, encodes a developmentally regulated membrane protein that is homologous to the Clostridium perfringens enterotoxin receptors. It is now clear that MBEC1 is a member of the claudin multigene family, and has been renamed claudin-5. TJs are key to the barrier function of the BBB, and lead to compartmentalization by creating a barrier for solute diffusion through the paracellular pathway.
Endothelial cells vary in their organization of TJs.
Although attempts have been made to correlate number and structure of tight junctions with tightness of the barrier, this relationship is not yet clear.