SLC19A1 and arthritic joint disease: We found that: 1) the expression of SLC19A1 was significantly reduced in inflamed whole hind limbs; 2) MTX itself and IL-6 + sIL-6R, but not TNF-α, directly decreased the expression of SLC19A1 in synovial cells; 3) MTX and IL-6 + sIL-6R reduced the uptake of MTX into synovial cells and 4) the efficacy of MTX on the arthritis score was augmented by concomitant use of anti-IL-6R antibody.