[Over-expression of mdr1/P-gp is associated with methotrexate resistance in patients with rheumatoid arthritis]

Objective To investigate the relationship between the gene expression of multidrug resisitance 1 (mdr1)/P-glycoprotein (P-gp) in peripheral blood mononuclear cells (PBMCs) and methotrexate (MTX) resistance in patients with rheumatoid arthritis (RA). Methods According to the grades of disease activity score 28 (DAS28) after taking MTX, RA patients were divided into sensitive group and resistant group. In addition, the healthy volunteers were enrolled as a control group. Real-time PCR was adopted to detect the expression of mdrl mRNA, and flow cytometry was used to detect the level and function of P-gp in PBMCs. Using the information obtained from these detections, we compared the expression of mdr1/P-gp between the three groups. Results Compared with the healthy group, the expression of P-gp was higher in the sensitive group and resistant group. Compared with the sensitive group, both mdr1 mRNA and P-gp expressions increased in the resistant group. Conclusion The over-expression of mdr1/P-gp in RA patients is related to the MTX resistance.