Monocyte infiltration is highly associated with loss of the tight junctionprotein zonula occludens in HIV-1-associated dementia

In human immunodeficiency virus (HIV)-1-associated dementia (HAD), conseque nces of interactions between infiltrating monocytes and brain endothelial c ells are not yet fully understood. This study investigated whether the bloo d-brain barrier is affected in brain tissue of patients suffering from HAD and whether it was possible to find a correlation with the presence or abse nce of monocytic cells, which have been suggested to play a major role in H AD. Immunohistochemical analysis for zonula occludens 1, a tight junction p rotein, and CD68, a macrophage marker, revealed that loss of tight junction immunoreactivity was highly correlated with monocyte infiltration and with HAD. This suggests that the presence of perivascular macrophages cells is associated with breakdown of the blood-brain barrier thereby facilitating i nfiltration of more monocytic cells hence enhancing disease progression.