Transporters for Antiretroviral Drugs in Colorectal CD4+ T Cells and Circulating α4β7 Integrin CD4+ T Cells: Implications for HIV Microbicides

Abstract

CD4+ T lymphocytes in the colorectal mucosa are key in HIV-1 transmission and dissemination. As such they are also the primary target for antiretroviral (ARV)-based rectal microbicides for pre-exposure prophylaxis. Drug transporters expressed in mucosal CD4+ T cells determine ARV distribution across the cell membrane and, most likely, efficacy of microbicides. We describe transporters for antiretroviral drugs in colorectal mucosal CD4+ T lymphocytes and compare gene expression with circulating α4β7+CD4+ T cells, which traffic to the intestine and have been shown to be preferentially infected by HIV-1. Purified total CD4+ T cells were obtained from colorectal tissue and blood samples by magnetic separation. CD4+ T cells expressing α4β7 integrin were isolated by fluorescence-activated cell sorting from peripheral blood mononuclear cells of healthy volunteers. Expressions of 15 efflux and uptake drug transporter genes were quantified using Taqman qPCR assays. Expression of efflux transporters MRP3, MRP5, and BCRP and uptake transporter CNT2 were significantly higher in colorectal CD4+ T cells compared to circulating CD4+ T cells (p = 0.01-0.03). Conversely, circulating α4β7+CD4+ T cells demonstrated significantly higher expression of OATPD compared to colorectal CD4+ T cells (p = 0.001). To the best of our knowledge this is the first report of drug transporter gene expression in colorectal CD4+ and peripheral α4β7+CD4+ T cells. The qualitative and quantitative differences in drug transporter gene expression profiles between α4β7+CD4+ T cells and total mucosal CD4+ T cells may have significant implications for the efficacy of rectally delivered ARV-microbicides. Most notably, we have identified efflux drug transporters that could be targeted by selective inhibitors or beneficial drug-drug interactions to enhance intracellular accumulation of antiretroviral drugs.

In Vivo Modulation of Cervicovaginal Drug Transporters and Tissue Distribution by Film-Released Tenofovir and Darunavir for Topical Prevention of HIV-1

“…We, and other groups, recently demonstrated expression of ABC and SLC transporters involved in transport of ARV drugs in human cervicovaginal tissues (9)(10)(11)(12) and colorectal tissue (13)(14)(15)(16) . We demonstrated expression of efflux transporters both in colorectal epithelial cells (13) and submucosal lymphocytes (14) suggesting that drug transporters could alter the disposition of topically-applied ARV drugs at the epithelial barrier and in sub-epithelial CD4+ T cells. That efflux transporters can alter tissue levels of ARV drugs in vivo has been demonstrated in a murine model of vaginal administration of tenofovir where inhibition of the efflux transporter ABCC4/MRP4 resulted in significantly higher concentrations of drug in cervical and vaginal tissues (17).…”

“…Uptake and persistence of topically applied ARV drugs may be influenced by membrane-bound ATP-binding cassette (ABC) solute efflux transporters and solute carrier (SLC) uptake transporters (7,8). We, and other groups, recently demonstrated expression of ABC and SLC transporters involved in transport of ARV drugs in human cervicovaginal tissues (9)(10)(11)(12) and colorectal tissue (13)(14)(15)(16) . We demonstrated expression of efflux transporters both in colorectal epithelial cells (13) and submucosal lymphocytes (14) suggesting that drug transporters could alter the disposition of topically-applied ARV drugs at the epithelial barrier and in sub-epithelial CD4+ T cells.…”

Comprehensive Study of Antiretroviral Drug Permeability at the Cervicovaginal Mucosa via an In Vitro Model

“…In a range of cell lines and tissue explants reflective of sites of HIV-1 mucosal transmission, we have previously demonstrated expression of both efflux and uptake transporters [2,3,34,35] for which reverse transcriptase inhibitors and protease inhibitors may be substrates [2,8,36]. In this study, we sought to investigate the permeability and mode of transport of three candidate ARV drugs for topical pre-exposure prophylaxis in an in vitro model of the cervicovaginal epithelial barrier.…”

The Pre-clinical Toolbox of Pharmacokinetics and Pharmacodynamics: in vitro and ex vivo Models

“…Indeed, differences in PK parameters such as Cmax and half-life have been observed between PBMCs and mucosal mononuclear cells isolated from digested mucosal tissues obtained after in vivo dosing of NHPs (Garcia-Lerma et al, 2011; Dobard et al, 2012; Massud et al, 2013) and humans (Yang et al, 2014; McGowan et al, 2015). Differences in expression of drug transporter have also been described between circulating and mucosal CD4 + T cells (Kis et al, 2010; Mukhopadhya et al, 2016b). Another limitation is that PBMCs exhibit anti-HIV-1 activity in the presence of bacterial lipopolysaccharide (LPS), which will therefore, artefactually enhance the inhibitory activity of biological specimens if they contain endotoxins (Geonnotti et al, 2010).…”