Lipopolysaccharide-enhanced transcellular transport of HIV-1 across the blood-brain barrier is mediated by the p38 mitogen-activated protein kinase pathway.

Chronic systemic inflammation in the late stage of human immunodeficiency virus type-1 (HIV-1) infection could increase neuroinvasion of infected monocytes and cell-free virus, causing an aggravation of neurological disorders in AIDS patients. We previously showed that the peripheral administration of lipopolysaccharide (LPS) enhanced the uptake across the blood-brain barrier (BBB) of the HIV-1 viral protein gp120. Brain microvessel endothelial cells are targets of LPS. Here, we investigated whether the direct interaction between LPS and the BBB also affected HIV-1 transport using primary mouse brain microvessel endothelial cells (BMECs). LPS produced a dose (1-100 microg/mL)- and time (0.5-4 h)-dependent increase in HIV-1 transport and a decrease in transendothelial electrical resistance (TEER). Whereas indomethacin (cyclooxygenase inhibitor) and L-NAME (NO synthase inhibitor) did not affect the LPS-induced changes in HIV-1 transport or TEER, pentoxifylline (TNF-alpha inhibitor) attenuated the decrease in TEER induced by LPS, but not the LPS-induced increase in HIV-1 transport. LPS also increased the phosphorylation of p44/42 MAPK and p38 MAPK but not that of JNK. U0126 (p44/42 MAPK inhibitor) and SP600125 (JNK inhibitor) did not inhibit the LPS-induced increase in HIV-1 transport although U0126 attenuated the reduction in TEER. SB203580 (p38 MAPK inhibitor) inhibited the LPS-induced increase in HIV-1 transport without affecting TEER. Thus, LPS-enhanced HIV-1 transport is independent of changes in TEER and so is attributed to increased transcellular trafficking of HIV-1 across the BBB. These results show that LPS increases HIV-1 transcellular transport across the BBB by a pathway that is mediated by p38 MAPK phosphorylation in BMECs.