Human brain microvascular endothelial cell traversal by Borrelia burgdorferi requires calcium signaling

Abstract

Neurological manifestations of Lyme disease (or neuroborreliosis) occur variably and while it is clear thatBorrelia burgdorferican invadethe nervous system, how it does so is not well understood. Pathogen penetration through the blood brain barrier (BBB) is often influ-enced by calcium signaling in the endothelial cells triggered by extracellular host-pathogen interactions. We examined the traversal ofB. burgdorferiacross the human BBB usingin vitromodel systems constructed of human brain microvascular endothelial cells (HBMEC)grown on Costar TranswellÔinserts. Pretreatment of the cell monolayers with BAPTA-AM (an intracellular calcium chelator) or phos-pholipase C (PLC) inhibitor U73122 inhibitedB. burgdorferitransmigration. By 5 h, BAPTA-AM significantly inhibited (82–99%; p <0.017)spirochete traversal of HBMEC compared to DMSO controls. Spirochete traversal was almost totally blocked (‡99%; p <0.017) afterpretreatment with the PLC-binhibitor U73122 as a result of barrier tightening based on electric cell-substrate impedance sensing(ECIS). The data suggest a role for calcium signaling in CNS spirochete invasion through endothelial cell barriers.