This is in agreement with studies reporting that chemotaxis and migration of Langerhans cells and T cells to the lymph nodes is associated with the activation of ABCC1, which mediates efflux of sphingolipid and cysteinyl leukotriene (55, 56)

This is in agreement with studies reporting that chemotaxis and migration of Langerhans cells and T cells to the lymph nodes is associated with the activation of ABCC1, which mediates efflux of sphingolipid and cysteinyl leukotriene (55, 56). protective effect of collagen/21 integrin on MTX-induced apoptosis also occurs in memory CD4+ T cells isolated from rheumatoid arthritis (RA) patients suggesting its clinical relevance. Together these results show that 21 integrin promotes MTX resistance of effector T cells, and suggest that it could contribute to the development of MTX resistance that is seen in RA. studies showed the implication of 21 integrin in the development of inflammatory diseases including experimental colitis (9), experimental autoimmune encephalomyelitis (10) and arthritis. In this case, we have shown that 21 integrin is expressed on RA synovial Th17 cells and its blockade reduces severity of collagen-induced arthritis and IL-7-induced bone loss in mice by reducing Th17 cell numbers and activity in the synovial tissue (11, 12). RA is a disabling disease in which Th17 and Th1 cells play a central role in the resulting synovitis and cartilage and bone erosion. Despite the introduction of several biologics, MTX EPHB4 is still the first line in RA therapy and the most frequently used disease-modifying anti-rheumatic drug. However, 30C40% of patients fail to respond or end-up developing resistance, thus becoming unresponsive (13, 14). The mechanisms accounting for MTX resistance in RA are still unclear although increased metabolism, altered target enzymes, and defective cellular uptake or increased MTX efflux through the expression and activity of ATP-binding cassette (ABC) drug transporters have been proposed (13, 14). These drug transporters, which are involved in cancer chemoresistance (15), have the ability to function, in an ATP-dependent manner, as a pump in order to extrude various endogenous (steroids, metabolites, ions) or exogenous substrates (drugs) out of the cells. MTX can act by blocking cell proliferation and cytokine production (16). However, one major effect of MTX is the induction of apoptosis in proliferating activated/effector T cells (16, 17). Decreased T cell numbers in the synovium of RA patients treated with MTX has also been reported (18, 19). Thus, it is likely that factors that promote resistance of effector T cells to apoptosis may BMS303141 have a significant BMS303141 role in MTX resistance. Since 21 integrin plays an important role in the survival and costimulation of effector T cell and in arthritis pathogenesis, we tested its contribution to MTX resistance using a tailored T cell model and T cells from RA patients. Our results show that 21 protects activated human polarized Th17 cells and RA effector/memory T cells from MTX-induced apoptosis through the ABC drug transporter ABCC1. Taken together our findings indicate that 21 integrin promotes Th17 cell resistance to MTX, and thus it could contribute to MTX resistance that is observed in RA. Materials and methods Reagents and antibodies Cell culture medium, X-vivo 15, was purchased from Lonza technologies (Walkersville, MD). Human cytokines (IL-6, TGF-, IL-2, IL-1, and IL-23) were purchased BMS303141 from R&D Systems (Minneapolis, MN). Type II collagen (referred hereafter as collagen) was from EPC Elastin Products Company (Owensville, MO), fibronectin, was from Sigma-Millipore (St. Louis, MO) and laminin-8 was from Biolamina (Stockholm, Sweden). The ABCC1 inhibitor MK571 and calcein-AM were from Calbiochem (San Diego, CA). The ABCG2 inhibitor, fumitremorgin c and ABCC1 inhibitor, reversan were from Sigma-Millipore (St-Louis, MO). MTX, the blocking anti-human 2 integrin (P1E6), the blocking anti-21 integrin (BHA2.1) and their appropriate isotypic control antibodies were from EMD Millipore (Billerica, MA). The blocking anti-human 1 integrin (4B4) and its control isotypic antibody were purchased from Beckman Coulter (Brea, CA). CD3/CD28 Dynabeads were from Invitrogen Dynal AS (Oslo, Norway). The anti-CD3 mAb (OKT3), PE-conjugated anti-human IFN (B27), PE-conjugated anti-human 2 integrin (12F1), FITC-conjugated anti-human ABCC1 (QCRL-3), Alexa 647-conjugated anti-human IL-17 (N49-653), PE-conjugated anti-ABCG2 (ATP-binding cassette sub-family G member 2) (5D3), their appropriate control isotypic antibodies and the FITC-annexin V apoptotic kit were from BD Biosciences (San Diego, USA). Anti–actin (C2) and anti-caspase-3 (E-8) antibodies were from Santa Cruz Biotechnology (Santa Cruz, CA). Ethical statement Our study was approved by the CHU de Qubec-Universit Laval ethical committee for clinical research. Healthy adult blood donors were recruited through the clinical research facility at the CHU de Qubec-Universit Laval Research Center. RA patients were recruited through the CHU.