Identification of the Neuroinvasive Pathogen Host Target, LamR, as an Endothelial Receptor for the Treponema pallidum Adhesin Tp0751.

subsp. is the causative agent of syphilis, a human-specific sexually transmitted infection that causes a multistage disease with diverse clinical manifestations. undergoes rapid vascular dissemination to penetrate tissue, placental, and blood-brain barriers and gain access to distant tissue sites. The rapidity and extent of dissemination are well documented, but the molecular mechanisms have yet to be fully elucidated. One protein that has been shown to play a role in treponemal dissemination is Tp0751, a adhesin that interacts with host components found within the vasculature and mediates bacterial adherence to endothelial cells under shear flow conditions. In this study, we further explore the molecular interactions of Tp0751-mediated adhesion to the vascular endothelium. We demonstrate that recombinant Tp0751 adheres to human endothelial cells of macrovascular and microvascular origin, including a cerebral brain microvascular endothelial cell line. Adhesion assays using recombinant Tp0751 N-terminal truncations reveal that endothelial binding is localized to the lipocalin fold-containing domain of the protein. We also confirm this interaction using live and show that spirochete attachment to endothelial monolayers is disrupted by Tp0751-specific antiserum. Further, we identify the 67-kDa laminin receptor (LamR) as an endothelial receptor for Tp0751 using affinity chromatography, coimmunoprecipitation, and plate-based binding methodologies. Notably, LamR has been identified as a receptor for adhesion of other neurotropic invasive bacterial pathogens to brain endothelial cells, including , , and , suggesting the existence of a common mechanism for extravasation of invasive extracellular bacterial pathogens. Syphilis is a sexually transmitted infection caused by the spirochete bacterium subsp. The continued incidence of syphilis demonstrates that screening and treatment strategies are not sufficient to curb this infectious disease, and there is currently no vaccine available. Herein we demonstrate that the adhesin Tp0751 interacts with endothelial cells that line the lumen of human blood vessels through the 67-kDa laminin receptor (LamR). Importantly, LamR is also a receptor for meningitis-causing neuroinvasive bacterial pathogens such as , , and Our findings enhance understanding of the Tp0751 adhesin and present the intriguing possibility that the molecular events of Tp0751-mediated treponemal dissemination may mimic the endothelial interaction strategies of other invasive pathogens.