Regulation of ABC Drug Efflux Transporters in Human T-Cells Exposed to an HIV Pseudotype

ATP-binding cassette (ABC) drug efflux transporters could contribute to low intracellular concentrations of antiretroviral drugs in HIV-1 cell reservoirs and sanctuary sites. Furthermore, the functional expression of these transporters could be induced in activated T-cells. Therefore, we investigated the expression of ABC drug efflux transporters in human T-cells exposed to an HIV pseudotype virus (pHIV), and further examined the potential involvement of the mammalian target of rapamycin (mTOR) signaling pathway in regulating their expression following exposure to pHIV. Additionally, we investigated the contribution of the drug efflux transporters to the inflammatory response following pHIV-induced T-cell activation. Human peripheral blood mononuclear cells (PBMCs) were exposed to HIV-1 envelope glycoprotein gp120, pHIV and/or mTOR inhibitors. The expression of ABC transporters, T-cell activation marker CD69, mTOR and pHIV was assessed in CD4 T-cells by Flow cytometry. mRNA and protein levels of proinflammatory cytokines (IL6, TNFα and INFγ) were examined in PBMCs by qPCR and ELISA analyses, respectively, following exposure to pHIV with or without inhibitors of mTOR or ABC transporters. The expression of ABC transporters (P-glycoprotein, breast cancer resistance protein and multi-drug resistance associated protein-1) was significantly increased in CD4 T-cells exposed to pHIV. Treatment with mTOR inhibitors attenuated pHIV-induced transporter expression, as well as mRNA and protein levels of IL6, TNFα and INFγ. Additionally, inhibition of P-gp or MRP1 activity resulted in lower concentrations of proinflammatory cytokines in supernatants of PBMC exposed to pHIV. Herein we present novel data demonstrating that upregulation of ABC drug efflux transporters could involve the mTOR signaling pathway in CD4 T-cells exposed to an HIV pseudotype. These transporters could limit antiretroviral drug penetration in HIV target T-cells. Furthermore, ABC transporters could potentially contribute to HIV-associated proinflammatory cytokine secretion.