P-glycoprotein (ABCB1) activity decreases raltegravir disposition in primary CD4+P-gp high cells and correlates with HIV-1 viral load

Altres ajuts: SAF2014-25560-RTo evaluate the role of P-glycoprotein (P-gp) and multidrug-resistant-protein 1 (MRP1) on raltegravir intracellular drug disposition in CD4+ T cells, investigate the effect of HIV-1 infection on P-gp expression and correlate HIV-1 viraemia with P-gp activity in primary CD4+ T cell subsets. The cellular accumulation ratio of [ 3 H]raltegravir was quantified in CD4+ T cell lines overexpressing either P-gp (CEM-P-gp) or MRP1 (CEM-MRP1) and in primary CD3+CD4+ T cells with high (P-gp high) and low P-gp activity (P-gp low); inhibition of efflux transporters was confirmed by the intracellular retention of calcein-AM. The correlation of P-gp activity with HIV-1 viraemia was assessed in naive and memory T cell subsets from 21 HIV-1-infected treatment-naive subjects. [ 3 H]Raltegravir cellular accumulation ratio decreased in CEM-P-gp cells (P < 0.0001). XR9051 (a P-gp inhibitor) and HIV-1 PIs reversed this phenomenon. Primary CD4+P-gp high cells accumulated less raltegravir (38.4% ± 9.6%) than P-gp low cells, whereas XR9051 also reversed this effect. In vitro HIV-1 infection of PBMCs and stimulation of CD4+ T cells increased P-gp mRNA and P-gp activity, respectively, while primary CD4+P-gp high T cells sustained a higher HIV-1 replication than P-gp low cells. A significant correlation between HIV-1 viraemia and P-gp activity was found in different CD4+ T cell subsets, particularly memory CD4+ T cells (r = 0.792, P < 0.0001). Raltegravir is a substrate of P-gp in CD4+ T cells. Primary CD4+P-gp high T cells eliminate intracellular raltegravir more readily than P-gp low cells and HIV-1 viraemia correlates with P-gp overall activity. Specific CD4+P-gp high T cell subsets could facilitate the persistence of viral replication in vivo and ultimately promote the appearance of drug resistance