HIV-1 infection alters monocyte interactions with human microvascular endothelial cells

HIV infection of monocytes resulted in a twofold elevation of adhesion molecule LFA-1 (both α(L)/CD11a and β₂/CD18 subunits) and LFA-3 (CD58), with no apparent increase in LFA-2 (CD2) or various β₁-integrins. Homotypic aggregation of monocytes was evident 2 h after exposure to virus and was inhibited by mAbs to both the α(L)- and β₂-subunits of LFA-1. HIV-infected monocytes also showed a marked increase in adherence to human capillary endothelial cell monolayers derived from brain, lung, and skin. This adherence was inhibited by mAb to either LFA-1 subunit and by mAb to the counter-receptor intercellular adhesion molecule-1. Cocultivation of HIV- infected monocytes with endothelial cells increased permeability of endothelial cell monolayers to ¹²⁵I albumin in transwell assay systems. The increased endothelial permeability induced by HIV-infected monocytes was associated with a substantial disruption of the endothelial cell monolayer. Morphologic disruption was not a direct toxic effect on endothelial cells, but appeared to be secondary to changes in endothelial cell-cell or cell- matrix interactions. Northern blot analysis showed increased expression of gelatinase B (92-kDa gelatinase), tissue inhibitor of metalloproteinase TIMP- 1, and TIMP-2 in the HIV-infected monocytes. Consistent with these Northern analyses, secretion of gelatinase activity in culture fluids of HIV-infected monocytes was also increased and was dependent on the stage of virus replication. Incubation of HIV-infected monocytes with the proteinase inhibitors TIMP-1 and TIMP-2 inhibited the increased permeability of endothelial cell monolayers to ¹²⁵I albumin. These results suggest possible mechanisms for extravasation of HIV-infected monocytes through vascular endothelium into tissue in early stages of HIV disease.