INTRACELLULAR PERSISTENCE OF BORRELIA-BURGDORFERI IN HUMAN SYNOVIAL-CELLS

To investigate if Borrelia burgdorferi can persist in resident joint c ells, an infection model using cell cultures of human synovial cells w as established and compared to the interaction of Borrelia burgdorferi and human macrophages. Borrelia burgdorferi were found attached to th e cell surface or folded into the cell membrane of synovial cells anal ysed by transmission electron and confocal laser scanning microscopy. In contrast to macrophages, morphologically intact Borrelia burgdorfer i were found in the cytosol of synovial cells without engulfment by ce ll membrane folds or phagosomes. Borrelia burgdorferi were isolated fr om parallel cultures. Treatment with ceftriaxone eradicated extracellu lar Borrelia burgdorferi, but spirochetes were reisolated after lysis of the synovial cells. Borrelia burgdorferi persisted inside synovial cells for at least 8 weeks. These data suggested that Borrelia burgdor feri might be able to persist within resident joint cells in vivo.