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Overexpression of P-glycoprotein on fibroblast-like synoviocytes in refractory rheumatoid arthritis patients: a potential mechanism for multidrug resistance in rheumatoid arthritis treatment

Author(s): Y.M. Liu, J.W. Chen, L.X. Chen, X. Xie and N. Mao

This study aims to investigate the role of P-glycoprotein (P-gp) expression level in drug resistance to disease-modifying anti-rheumatic drugs in refractory rheumatoid arthritis (RRA). We evaluated and compared the expression levels of P-gp in fibroblast-like synoviocyte (FLS) cells in patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and investigated the potential mechanism of P-gp-induced multidrug resistance in RRA. Ten patients were enrolled and divided into two groups: six in the RA group and four in the OA group. The expression level of P-gp in FLS cells was detected by western blotting following cell culture. A linear correlation algorithm was used to assess the association between the level of P-gp and disease activity (using DAS28 scoring), as well as the duration of methotrexate (MTX) treatment in the RRA patients. The level of P-gp in the RRA patients was markedly higher than that in the OA patients (P t = -4.179). There was a positive linear correlation between the P-gp level in FLS cells and the duration of MTX treatment in the RRA group (ÐÃ?Â? = 0.733, P 0.05). P-gp might be upregulated during the progression of RRA, which possibly correlates with the development of resistance to MTX.