HIV-1 Tat and opioids act independently to limit antiretroviral brain concentrations and reduce blood-brain barrier integrity.

Poor antiretroviral penetration may contribute to human immunodeficiency virus (HIV) persistence within the brain and to neurocognitive deficits in opiate abusers. To investigate this problem, HIV-1 Tat protein and morphine effects on blood-brain barrier (BBB) permeability and drug brain penetration were explored using a conditional HIV-1 Tat transgenic mouse model. Tat and morphine effects on the leakage of fluorescently labeled dextrans (10-, 40-, and 70-kDa) into the brain were assessed. To evaluate effects on antiretroviral brain penetration, Tat+ and Tat- mice received three antiretroviral drugs (dolutegravir, abacavir, and lamivudine) with or without concurrent morphine exposure. Antiretroviral and morphine brain and plasma concentrations were determined by LC-MS/MS. Morphine exposure, and, to a lesser extent, Tat, significantly increased tracer leakage from the vasculature into the brain. Despite enhanced BBB breakdown evidenced by increased tracer leakiness, morphine exposure led to significantly lower abacavir concentrations within the striatum and significantly less dolutegravir within the hippocampus and striatum (normalized to plasma). P-glycoprotein, an efflux transporter for which these drugs are substrates, expression and function were significantly increased in the brains of morphine-exposed mice compared to mice not exposed to morphine. These findings were consistent with lower antiretroviral concentrations in brain tissues examined. Lamivudine concentrations were unaffected by Tat or morphine exposure. Collectively, our investigations indicate that Tat and morphine differentially alter BBB integrity. Morphine decreased brain concentrations of specific antiretroviral drugs, perhaps via increased expression of the drug efflux transporter, P-glycoprotein.

Effects of HIV-1 Tat and Methamphetamine on Blood-Brain Barrier Integrity and Function In Vitro.

Human immunodeficiency (HIV) infection results in neurocognitive deficits in about one half of infected individuals. Despite systemic effectiveness, restricted antiretroviral penetration across the blood-brain barrier (BBB) is a major limitation in fighting central nervous system (CNS)-localized infection. Drug abuse exacerbates HIV-induced cognitive and pathological CNS changes. This study's purpose was to investigate the effects of the HIV-1 protein Tat and methamphetamine on factors affecting drug penetration across an in vitro BBB model. Factors affecting paracellular and transcellular flux in the presence of Tat and methamphetamine were examined. Transendothelial electrical resistance, ZO-1 expression, and lucifer yellow (a paracellular tracer) flux were aspects of paracellular processes that were examined. Additionally, effects on P-glycoprotein (P-gp) and multidrug resistance protein 1 (MRP-1) mRNA (via quantitative PCR [qPCR]) and protein (via immunoblotting) expression were measured; Pgp and MRP-1 are drug efflux proteins. Transporter function was examined after exposure of Tat with or without methamphetamine using the P-gp substrate rhodamine 123 and also using the dual P-gp/MRP-1 substrate and protease inhibitor atazanavir. Tat and methamphetamine elicit complex changes affecting transcellular and paracellular transport processes. Neither Tat nor methamphetamine significantly altered P-gp expression. However, Tat plus methamphetamine exposure significantly increased rhodamine 123 accumulation within brain endothelial cells, suggesting that treatment inhibited or impaired P-gp function. Intracellular accumulation of atazanavir was not significantly altered after Tat or methamphetamine exposure. Atazanavir accumulation was, however, significantly increased by simultaneous inhibition of P-gp and MRP. Collectively, our investigations indicate that Tat and methamphetamine alter aspects of BBB integrity without affecting net flux of paracellular compounds. Tat and methamphetamine may also affect several aspects of transcellular transport.

Independent actions by HIV-1 Tat and morphine to increase recruitment of monocyte-derived macrophages into the brain in a region-specific manner.

Despite advances in the treatment of human immunodeficiency virus (HIV), approximately one-half of people infected with HIV (PWH) experience neurocognitive impairment. Opioid use disorder (OUD) can exacerbate the cognitive and pathological changes seen in PWH. HIV increases inflammation and immune cell trafficking into the brain; however, less is known about how opioid use disorder affects the recruitment of immune cells. Accordingly, we examined the temporal consequences of HIV-1 Tat and/or morphine on the recruitment of endocytic cells (predominantly perivascular macrophages and microglia) in the dorsal striatum and hippocampus by infusing multi-colored, fluorescently labeled dextrans before and after exposure. To address this question, transgenic mice that conditionally expressed HIV-1 Tat (Tat+), or their control counterparts (Tat-), received three sequential intracerebroventricular (i.c.v.) infusions of Cascade Blue-, Alexa Fluor 488-, and Alexa Fluor 594-labeled dextrans, respectively infused 1 day before, 1-day after, or 13-days after morphine and/or Tat exposure. At the end of the study, the number of cells labeled with each fluorescent dextran were counted. The data demonstrated a significantly higher influx of newly-labeled cells into the perivascular space than into the parenchyma. In the striatum, Tat or morphine exposure increased the number of endocytic cells in the perivascular space, while only morphine increased the recruitment of endocytic cells into the parenchyma. In the hippocampus, morphine (but not Tat) increased the influx of dextran-labeled cells into the perivascular space, but there were too few labeled cells within the hippocampal parenchyma to analyze. Collectively, these data suggest that HIV-1 Tat and morphine act independently to increase the recruitment of endocytic cells into the brain in a region-specific manner.

New Drugs in the Pipeline for the Treatment of HIV: a Review.

PURPOSE OF REVIEW: The purpose of this paper is to review therapies with new mechanisms of action for the treatment of HIV that are at least in phase 2 clinical trials. RECENT FINDINGS: There are several new mechanisms of action being represented within clinical development, including histone deacetylase (HDAC) inhibitors, gene therapies, broadly neutralizing anti-HIV antibodies, immune modulation, and drugs with new mechanisms to block HIV entry. The new therapies are being developed for both as add-on therapy to existing combination antiretroviral therapy and as agents to be used during treatment interruption. The current drugs in development have had varying degrees of success in the early trials. Each of these new drugs may potentially fill a void in current antiretroviral therapy (ART) therapies, which will ultimately lead to improved outcomes in HIV-infected individuals.

HIV-1 Tat disrupts blood-brain barrier integrity and increases phagocytic perivascular macrophages and microglia in the dorsal striatum of transgenic mice.

HIV-1 infection results in blood-brain barrier (BBB) disruption, which acts as a rate-limiting step for HIV-1 entry into the CNS and for subsequent neuroinflammatory/neurotoxic actions. One mechanism by which HIV may destabilize the BBB involves actions of the HIV-1 regulatory protein, trans-activator of transcription (Tat). We utilized a conditional, Tat-expressing transgenic murine model to examine the influence of Tat1-86 expression on BBB integrity and to assess the relative numbers of phagocytic perivascular macrophages and microglia within the CNS in vivo. The effects of Tat exposure on sodium-fluorescein (Na-F; 0.376kDa), horseradish peroxidase (HRP; 44kDa), and Texas Red-labeled dextran (70kDa) leakage into the brain were assessed in Tat-exposed (Tat+) and control (Tat-) mice. Exposure to HIV-1 Tat significantly increased both Na-F and HRP, but not the larger sized Texas Red-labeled dextran, confirming BBB breakdown and also suggesting the breach was limited to molecules <70kDa. Additionally, at 5 d after Tat induction, Alexa Fluor® 488-labeled dextran was bilaterally infused into the lateral ventricles 5 d before the termination of the experiment. Within the caudate/putamen, Tat induction increased the proportion of dextran-labeled Iba-1+ phagocytic perivascular macrophages (∼5-fold) and microglia (∼3-fold) compared to Tat- mice. These data suggest that HIV-1 Tat exposure is sufficient to destabilize BBB integrity and to increase the presence of activated, phagocytic, perivascular macrophages and microglia in an in vivo model of neuroAIDS.

Androgen receptor splice variant 7 (AR-V7) and drug efficacy in castration-resistant prostate cancer: Biomarker for treatment selection exclusion or inclusion?

Currently there are no molecular biomarkers used to help guide treatment selection for those patients with castration-resistant prostate cancer. A recent study published in JAMA Oncology (Antonarakis et al.) presents evidence supporting the potential use of androgen receptor splice variant 7 as a biomarker for optimal treatment selection in this population.

Identification of novel SNPs associated with risk and prognosis in patients with castration-resistant prostate cancer.

AIM: Metabolism and transport play major roles in life-long exposure to endogenous and exogenous carcinogens. We therefore explored associations between polymorphisms in absorption, distribution, metabolism and elimination genes and the risk and prognosis of castration-resistant prostate cancer (CRPC). MATERIALS & METHODS: A total of 634 genotypes were tested in 74 patients using the Affymetrix DMETv1.0 platform. RESULTS: No relation to risk was found. Three SNPs were associated with CRPC prognosis in Caucasians: ABCB11 rs7602171G>A (p = 0.003; n = 30; hazard ratio [HR]: 0.307), GSTP1 rs1799811C>T (p = 0.001; n = 38; HR: 0.254) and SLC5A6 rs1395 (p = 0.004; n = 35; HR: 3.15). Two other polymorphisms among Caucasians were associated with interesting trends: ABCB4 rs2302387C>T (p = 0.039) and ABCC5 rs939339A>G (p = 0.018). CONCLUSION: This exploratory study is the first to show that polymorphisms in several absorption, distribution, metabolism and elimination genes may be associated with CRPC prognosis.