PDLIM7 and arthritic joint disease: Both wild type and lmp1-complemented B. burgdorferi caused severe inflammation, but lmp1 mutants induced less severe disease, as reflected by the histopathological signs of carditis (Figure 4A and 4B), development of swelling in the tibiotarsal joints (Figure 4C), and histopathological signs of arthritis (Figure 4D).