ABSTRACT
Background Appropriate interactions between antiretroviral therapies (ART) and drug transporters and metabolizing enzymes at the blood brain barrier (BBB) are critical to ensure adequate dosing of the brain to achieve HIV suppression. These proteins are modulated by demographic and lifestyle factors, including substance use. While understudied, illicit substances share drug transport and metabolism pathways with ART, increasing the potential for adverse drug:drug interactions. This is particularly important when considering the brain as it is relatively undertreated compared to peripheral organs and is vulnerable to substance use-mediated damage.
Methods We used an in vitro model of the human BBB to determine the extravasation of three first-line ART drugs, emtricitabine (FTC), tenofovir (TFV), and dolutegravir (DTG), in the presence and absence of cocaine, which served as our illicit substance model. The impact of cocaine on BBB integrity and permeability, drug transporters, metabolizing enzymes, and their master transcriptional regulators were evaluated to determine the mechanisms by which substance use impacted ART central nervous system (CNS) availability.
Results We determined that cocaine had a selective impact on ART extravasation, where it increased FTC’s ability to cross the BBB while decreasing TFV. DTG concentrations that passed the BBB were below quantifiable limits. Interestingly, the potent neuroinflammatory modulator, lipopolysaccharide, had no effect on ART transport, suggesting a specificity for cocaine. Unexpectedly, cocaine did not breach the BBB, as permeability to albumin and tight junction proteins and adhesion molecules remained unchanged. Rather, cocaine selectively decreased the pregnane-x receptor (PXR), but not constitutive androstane receptor (CAR). Consequently, drug transporter expression and activity decreased in endothelial cells of the BBB, including p-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 4 (MRP4). Further, cytochrome P450 3A4 (CYP3A4) enzymatic activity increased following cocaine treatment that coincided with decreased expression. Finally, cocaine modulated adenylate kinases are required to facilitate biotransformation of ART prodrugs to their phosphorylated, pharmacologically active counterparts.
Conclusion Our findings indicate that additional considerations are needed in CNS HIV treatment strategies for people who use cocaine, as it may limit ART efficacy through regulation of drug transport and metabolizing pathways at the BBB.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
LIST OFF ABBREVIATIONS
- (TBS-T)
- 1X Tris-Buffered Saline containing 0.1% Tween-20
- (BFC)
- 7-benzyloxy-4-trifluoromethylcoumarin
- (HFC)
- 7-hydroxy-4-trifluoromethylcoumarin
- (ABC)
- ATP-binding cassette
- (ART)
- Antiretroviral therapy
- (AIDS)
- Acquired immunodeficiency syndrome
- (ALCAM)
- Activated leukocyte cell adhesion molecule
- (BBB)
- Blood brain barrier
- (BCRP)
- Breast Cancer Resistant Protein
- (CTSB)
- Cathepsin B
- (CNS)
- Central nervous system
- (COL6A1)
- Collagen Type VI Alpha 1 Chain
- (cART)
- Combined ART
- (M199C)
- Complete M199 media
- (DPBS)
- Dulbecco’s phosphate-buffered saline without calcium or magnesium
- (DTG)
- Dolutegravir
- (EDTA)
- Ethylenediaminetetraacetic acid
- (FTC)
- Emtricitabine
- (ENT1)
- Equilitative nucleoside transporter
- (EBA)
- Evans Blue dye conjugated to albumin
- (FBS)
- Fetal bovine serum
- (HPX)
- Hemopexin
- (HIV)
- Human immunodeficiency virus-1
- (ICAM-1)
- Intercellular Adhesion Molecule 1
- (JAM-A)
- Junctional adhesion molecule A
- (LPS)
- Lipopolysaccharide
- (MIF)
- Macrophage Migration Inhibitory Factor
- (MFI)
- P Mean fluorescence intensity
- (M199)
- Medium 199
- (MRP4)
- Multidrug resistance-associated protein 1
- (MRP2)
- Multidrug resistance-associated protein 2
- (MRP4)
- Multidrug resistance-associated protein 4
- (NRP2)
- Neuropilin 2
- (OAT1)
- Organic anion transporter 1
- (OAT3)
- Organic anion transporter 3
- (OATP1A2)
- Organic anion-transporting polypeptide 1A2
- (OD620)
- Optical density at 620 nm
- (PECAM-1)
- Platelet-endothelial cell adhesion molecule
- (P-gp)
- P-glycoprotein
- (PBS)
- Phosphate buffered saline
- (ICALM)
- Phosphatidylinositol Binding Clathrin Assembly Protein
- (PrEP)
- Pre-exposure prophylaxis
- (PXR)
- Pregnane-X receptor
- (ROI)
- Region of interest
- (RFU)
- Relative fluorescent intensity
- (SLC)
- Solute carrier
- (TFV)
- transporter Tenofovir
- (VWF)
- Vitronectin
- (VWF)
- Von Willebrand Factor
- (Zo-1)
- Zonula occludens-1