Jemiina Salo, Annukka Pietikäinen, Mirva Söderström, Kaisa Auvinen, Marko Salmi, Rhodaba Ebady, Tara J. Moriarty, Matti K. Viljanen, Jukka Hytönen

 Bacterial pathogens causing systemic infections disseminate from the initial infection focus to the target organs usually through the blood vasculature. To be able to colonize various organs, bacteria need to adhere to the endothelial cells of the vascular wall, and the adhesion must be strong enough to resist the shear force of the blood flow. Borrelia burgdorferi sensu lato (s.l.) spirochetes, the causative agents of the tick-borne Lyme borreliosis, disseminate hematogenously from the tick bite site to the joints, the heart and the central nervous system of the patient.  We used both wild type and genetically modified B. burgdorferi s.l. bacteria, recombinant borrelia adhesins, and an array of adhesion assays carried out both under stationary and flow conditions to investigate the molecular mechanisms of borrelial adhesion to human endothelial cells.  Borrelia garinii, a member of the B. burgdorferi s.l. complex, adhered to biglycan expressed by human endothelial cells in a flow tolerant manner. The adhesion was mediated by the DbpA and B surface molecules of B. garinii.  The proteoglycan biglycan is a receptor molecule for flow resistant adhesion of the bacterial pathogen B. garinii on human endothelial cells.