Effects of HIV-1 Tat and Methamphetamine on Blood-Brain Barrier Integrity and FunctionIn Vitro

Abstract

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.

Discovery of Second-Generation NLRP3 Inflammasome Inhibitors: Design, Synthesis, and Biological Characterization

“…29, 30 Apparent permeability ( P app ) was calculated using P app = (dX/dT • V r )/(A • C o ), where dX/dT is the mass of transported compound (X) over time (T), V r is the volume in the receiver compartment, A is the surface area of the membrane insert, and C o is the initial concentration in the donor compartment. 30 We first examined the potential cytotoxicity of 17 on hCMEC/D3 cells to rule out any potential interference with results interpretation, and the results demonstrated that 17 at 20 μM did not show significant toxic effects on these cells (Figure 7A). The apical-to-basolateral (A to B) and basolateral-to-apical (B to A) P app of 17 was 5.21 ± 0.56 × 10 −6 and 1.11 ± 0.12 × 10 −6 cm/sec, respectively (Figure 7B).…”

Colon dysregulation in methamphetamine self-administering HIV-1 transgenic rats

“…However, following methamphetamine exposure, the pattern and distribution of staining was discontinuous, regardless of genotype. In a recent study by Patel et al , exposure to Tat and methamphetamine altered ZO-1 expression in an in vitro model of the blood-brain barrier; however, alterations in functional permeability were not obtained [ 49 ]. This suggests that alterations in the distribution and expression of multiple tight junction proteins may play a role in the functional permeability that was observed in the current in vivo study with non-Tg and Tg rats.…”

Important role of microglia in HIV-1 associated neurocognitive disorders and the molecular pathways implicated in its pathogenesis

“…In fact, limiting the bidirectional trafficking of HIV-infected macrophages into the CNS and restricting HIV replication within CNS compartments is of critical importance in reducing the production of viral proteins and limiting the CNS inflammation that drives HAND [ 64 ]. Of note, drug abuse exacerbates the pathological CNS changes found in patients with HAND [ 69 ]. For example, there is experimental and clinical evidence indicating that HIV neuropathogenesis and neurocognitive deficits are exacerbated with co-exposure to methamphetamine (meth) [ 63 ].…”

“…Whereas monocyte-derived macrophages are most commonly used to model HIV-1 infection, HIV-1 replication has also been described in cultured primary microglia isolated from adult, infant, or foetal brains [ 125 ]. The presence of HIV-1 DNA has also been described in astrocytes and neurons isolated from HIV-1 encephalitis brain tissue by LCM [ 69 , 124 ]. However, it is not clear if this indicates a true latent infection or what role it might play in the pathogenesis of the infection.…”