Maraviroc Concentrations in Cerebrospinal Fluid in HIV-Infected Patients

Development of Anti-HIV Therapeutics: From Conventional Drug Discovery to Cutting-Edge Technology

The efforts to discover HIV therapeutics have continued since the first human immunodeficiency virus (HIV) infected patient was confirmed in the 1980s. Ten years later, the first HIV drug, zidovudine (AZT), targeting HIV reverse transcriptase, was developed. Meanwhile, scientists were enlightened to discover new drugs that target different HIV genes, like integrase, protease, and host receptors. Combination antiretroviral therapy (cART) is the most feasible medical intervention to suppress the virus in people with HIV (PWH) and control the epidemic. ART treatment has made HIV a chronic infection rather than a fatal disease, but ART does not eliminate latent reservoirs of HIV-1 from the host cells; strict and life-long adherence to ART is required for the therapy to be effective in patients. In this review, we first discussed the scientific history of conventional HIV drug discovery since scientists need to develop more and more drugs to solve drug-resistant issues and release the side effects. Then, we summarized the novel research technologies, like gene editing, applied to HIV treatment and their contributions to eliminating HIV as a complementary therapy.

Antiretroviral Therapy Intensification for Neurocognitive Impairment in Human Immunodeficiency Virus

BACKGROUND

Neurocognitive impairment (NCI) in people with HIV (PWH) on antiretroviral therapy (ART) is common and may result from persistent HIV replication in the central nervous system.

METHODS

A5324 was a randomized, double-blind, placebo-controlled, 96-week trial of ART intensification with dolutegravir (DTG) + MVC, DTG + Placebo, or Dual - Placebo in PWH with plasma HIV RNA <50 copies/mL on ART and NCI. The primary outcome was the change on the normalized total z score (ie, the mean of individual NC test z scores) at week 48.

RESULTS

Of 357 screened, 191 enrolled: 71% male, 51% Black race, 22% Hispanic ethnicity; mean age 52 years; mean CD4+ T-cells 681 cells/µL. Most (65%) had symptomatic HIV-associated NC disorder. Study drug was discontinued due to an adverse event in 15 (8%) and did not differ between arms (P = .17). Total z score, depressive symptoms, and daily functioning improved over time in all arms with no significant differences between them at week 48 or later. Adjusting for age, sex, race, study site, efavirenz use, or baseline z score did not alter the results. Body mass index modestly increased over 96 weeks (mean increase 0.32 kg/m2, P = .006) and did not differ between arms (P > .10).

CONCLUSIONS

This is the largest, randomized, placebo-controlled trial of ART intensification for NCI in PWH. The findings do not support empiric ART intensification as a treatment for NCI in PWH on suppressive ART. They also do not support that DTG adversely affects cognition, mood, or weight.

CCR5 antagonist reduces HIV-induced amyloidogenesis, tau pathology, neurodegeneration, and blood-brain barrier alterations in HIV-infected hu-PBL-NSG mice

BACKGROUND

Neurocognitive impairment is present in 50% of HIV-infected individuals and is often associated with Alzheimer's Disease (AD)-like brain pathologies, including increased amyloid-beta (Aβ) and Tau hyperphosphorylation. Here, we aimed to determine whether HIV-1 infection causes AD-like pathologies in an HIV/AIDS humanized mouse model, and whether the CCR5 antagonist maraviroc alters HIV-induced pathologies.

METHODS

NOD/scid-IL-2Rγcnull mice engrafted with human blood leukocytes were infected with HIV-1, left untreated or treated with maraviroc (120 mg/kg twice/day). Human cells in animal's blood were quantified weekly by flow cytometry. Animals were sacrificed at week-3 post-infection; blood and tissues viral loads were quantified using p24 antigen ELISA, RNAscope, and qPCR. Human (HLA-DR+) cells, Aβ-42, phospho-Tau, neuronal markers (MAP 2, NeuN, neurofilament-L), gamma-secretase activating protein (GSAP), and blood-brain barrier (BBB) tight junction (TJ) proteins expression and transcription were quantified in brain tissues by immunohistochemistry, immunofluorescence, immunoblotting, and qPCR. Plasma Aβ-42, Aβ-42 cellular uptake, release and transendothelial transport were quantified by ELISA.

RESULTS

HIV-1 significantly decreased human (h)CD4+ T-cells and hCD4/hCD8 ratios; decreased the expression of BBB TJ proteins claudin-5, ZO-1, ZO-2; and increased HLA-DR+ cells in brain tissues. Significantly, HIV-infected animals showed increased plasma and brain Aβ-42 and phospho-Tau (threonine181, threonine231, serine396, serine199), associated with transcriptional upregulation of GSAP, an enzyme that catalyzes Aβ formation, and loss of MAP 2, NeuN, and neurofilament-L. Maraviroc treatment significantly reduced blood and brain viral loads, prevented HIV-induced loss of neuronal markers and TJ proteins; decreased HLA-DR+ cells infiltration in brain tissues, significantly reduced HIV-induced increase in Aβ-42, GSAP, and phospho-Tau. Maraviroc also reduced Aβ retention and increased Aβ release in human macrophages; decreased the receptor for advanced glycation end products (RAGE) and increased low-density lipoprotein receptor-related protein-1 (LRP1) expression in human brain endothelial cells. Maraviroc induced Aβ transendothelial transport, which was blocked by LRP1 antagonist but not RAGE antagonist.

CONCLUSIONS

Maraviroc significantly reduced HIV-induced amyloidogenesis, GSAP, phospho-Tau, neurodegeneration, BBB alterations, and leukocytes infiltration into the CNS. Maraviroc increased cellular Aβ efflux and transendothelial Aβ transport via LRP1 pathways. Thus, therapeutically targeting CCR5 could reduce viremia, preserve the BBB and neurons, increased brain Aβ efflux, and reduce AD-like neuropathologies.

Pharmacology of HIV Cure: Site of Action

Despite significant advances in HIV treatment over the past 30 years, critical barriers to an HIV cure persist. The HIV reservoir, defined at both the cellular and anatomical level, constitutes the main barrier to cure. While the mechanisms underlying the reservoir are not yet well understood, one theory to explain persistence at the anatomical level is that subtherapeutic exposure to antiretroviral therapy (ART) within certain tissue compartments permits ongoing replication. Characterizing ART pharmacology throughout the body is important in the context of these potential pharmacologic sanctuaries and for maximizing the probability of success with forthcoming cure strategies that rely on latency reversal and require ART to prevent reseeding the reservoir. In this review, we provide a comprehensive overview of ART and latency reversal agent distribution at the site of action for HIV cure (i.e., anatomical sites commonly associated with HIV persistence, such as lymphoid organs and the central nervous system). We also discuss methodologic approaches that provide insight into HIV cure pharmacology, including experimental design and advances within the computational, pharmaceutical, and analytical chemistry fields. The information discussed in this review will assist in streamlining the development of investigational cure strategies by providing a roadmap to ensure therapeutic exposure within the site of action for HIV cure.

Changes in cerebral function parameters with maraviroc-intensified antiretroviral therapy in treatment naive HIV-positive individuals

BACKGROUND

Maraviroc-intensified antiretroviral therapy (ART) may be associated with cognitive benefits.

METHODS

Therapy-naive, cognitively asymptomatic, HIV-positive individuals were randomly allocated on a 1 : 1 basis to standard ART (Arm1: tenofovir-emtricitabine and atazanavir/ritonavir) or maraviroc intensified ART (Arm2: abacavir-lamivudine and darunavir/ritonavir/maraviroc). Over 48 weeks, detailed assessments of cognitive function tests were undertaken and cerebral metabolites measured using proton magnetic resonance spectroscopy. Our primary endpoint was mean change in cognitive function across treatment arms with factors associated with cognitive function changes also assessed.

RESULTS

Of 60 individuals randomized (30 Arm1 and 30 Arm2), 58 were men and 44 of white ethnicity. Treatment groups had similar disease characteristics including overall mean (SD) baseline CD4 cell count 428 (209) and 414 (229) cells/μl, Arms1 and 2, respectively. At week 48, plasma HIV RNA was less than 50 copies/ml in 55 of 56 of those completing study procedures. Cognitive function improved over 48 weeks [mean change z-score (SD) 0.16 (0.09) Arm1 and 0.25 (0.08) Arm2, P = 0.96 for differences between study arms]. A greater increase in frontal grey matter N-acetyl aspartate/creatine ratio was observed in Arm1 [ratio change of 0.071 (SD 0.16)] versus Arm2 [change -0.097 (SD 0.18), P = 0.009], although this was not associated with changes in cognitive function (P = 0.17).

CONCLUSION

Maraviroc-intensified ART had no demonstrable benefit on cognitive function in individuals initiating ART. Greater improvement in neuronal metabolites (N-acetyl aspartate/creatine) was observed with standard ART. Future work should focus on maraviroc-intensified ART in individuals with cognitive impairment.

CSF inflammatory markers and neurocognitive function after addition of maraviroc to monotherapy darunavir/ritonavir in stable HIV patients: the CINAMMON study

CINAMMON is a phase IV, open-label, single-arm, pilot study assessing maraviroc (MVC) in the central nervous system (CNS) when added to darunavir/ritonavir monotherapy (DRV/r) in virologically suppressed HIV-infected subjects. CCR5 tropic participants on DRV/r were recruited. Participants remained on DRV/r for 12 week (w) (control phase). MVC 150 mg qd was added w12-w36 (intervention phase). Lumbar puncture (LP) and neurocognitive function (Cogstate) examinations scheduled at baseline, w12 and w36; MRI before w12, again at w36. Primary endpoint was CSF inflammatory marker changes during intervention phase. Secondary endpoints included changes in NC function and MRI parameters. CSF/plasma DRV/r concentrations measured at w12 and w36, MVC at w36. Nineteen patients recruited, 15 completed (17M, 2F). Dropouts: headache (2), knee problem (could not attend, 1), personal reasons (1). Mean age (range) 45.4 years (27.2-65.1), 13/19 white, 10/19 MSM. No changes in selected CSF markers were seen w12-w36. Overall NC function did not improve w12-w36: total age adjusted z score improved by 0.27 (weighted paired t test; p = 0.11); for executive function only, age adjusted z score improved by 0.54 (p = 0.03). MRI brain parameters unchanged. DRV plasma:CSF concentration ratio unchanged between w12 (132) and w36 (112; p = 0.577, Wilcoxon signed-rank). MVC plasma:CSF concentration ratio was 35 at w36. No changes in neuroinflammatory markers seen. In this small study, addition of 24w MVC 150 mg qd to stable DRV/r monotherapy showed possible improvement in executive function with no global NC effect. Learning effect cannot be excluded. This effect should be further evaluated.

Reduced antiretroviral drug efficacy and concentration in HIV-infected microglia contributes to viral persistence in brain

BACKGROUND

In patients with HIV/AIDS receiving antiretroviral therapy (ART), HIV-1 persistence in brain tissue is a vital and unanswered question. HIV-1 infects and replicates in resident microglia and trafficking macrophages within the brain although the impact of individual ART drugs on viral infection within these brain myeloid cells is unknown. Herein, the effects of contemporary ART drugs were investigated using in vitro and in vivo models of HIV-1 brain infection.

RESULTS

The EC₅₀ values for specific ART drugs in HIV-infected human microglia were significantly higher compared to bone marrow-derived macrophages and peripheral blood mononuclear cells. Intracellular ART drug concentrations in microglia were significantly lower than in human lymphocytes. In vivo brain concentrations of ART drugs in mice were 10 to 100-fold less in brain tissues compared with plasma and liver levels. In brain tissues from untreated HIV-infected BLT mice, HIV-encoded RNA, DNA and p24 were present in human leukocytes while ART eradicated viral RNA and DNA in both brain and plasma. Interruption of ART resulted in detectable viral RNA and DNA and increased human CD68 expression in brains of HIV-infected BLT mice. In aviremic HIV/AIDS patients receiving effective ART, brain tissues that were collected within hours of last ART dosing showed HIV-encoded RNA and DNA with associated neuroinflammatory responses.

CONCLUSIONS

ART drugs show variable concentrations and efficacies in brain myeloid cells and tissues in drug-specific manner. Despite low drug concentrations in brain, experimental ART suppressed HIV-1 infection in brain although HIV/AIDS patients receiving effective ART had detectable HIV-1 in brain. These findings suggest that viral suppression in brain is feasible but new approaches to enhancing ART efficacy and concentrations in brain are required for sustained HIV-1 eradication from brain.

HIV-associated neurocognitive disorders: recent advances in pathogenesis, biomarkers, and treatment

HIV-associated neurocognitive disorders (HAND) remain prevalent despite plasma viral suppression by antiretroviral agents. In fact, the prevalence of milder subtypes of cognitive impairment is increasing. Neuropsychologic testing remains the "gold standard" of diagnosis; however, this is time consuming and costly in a resource-poor environment. Recently developed screening tools, such as CogState and the revised HIV dementia scale, have very good sensitivity and specificity in the more severe stages of HAND. However, questions remain regarding the utility of, optimal population for, and insensitivity of tests in mild HAND. Recognition of ongoing viral persistence and the inflammatory milieu in the central nervous system (CNS) has advanced our understanding of the pathogenesis of HAND and facilitated the development of biomarkers of CNS disease. The importance of the monocyte-macrophage lineage cell and the astrocyte as viral reservoirs, HIV viral proteins, self-perpetuating CNS inflammation, and CCR5 chemokine receptor neurotropism has been identified. Whilst biomarkers demonstrate monocyte activation, inflammation, and neuronal injury, they remain limited in their clinical utility. The improved understanding of pathogenic mechanisms has led to novel approaches to the treatment of HAND; however, despite these advances, the optimal management is still undefined.

Pharmacokinetic, Pharmacogenetic, and Other Factors Influencing CNS Penetration of Antiretrovirals

Neurological complications associated with the human immunodeficiency virus (HIV) are a matter of great concern. While antiretroviral (ARV) drugs are the cornerstone of HIV treatment and typically produce neurological benefit, some ARV drugs have limited CNS penetration while others have been associated with neurotoxicity. CNS penetration is a function of several factors including sieving role of blood-brain and blood-CSF barriers and activity of innate drug transporters. Other factors are related to pharmacokinetics and pharmacogenetics of the specific ARV agent or mediated by drug interactions, local inflammation, and blood flow. In this review, we provide an overview of the various factors influencing CNS penetration of ARV drugs with an emphasis on those commonly used in sub-Saharan Africa. We also summarize some key associations between ARV drug penetration, CNS efficacy, and neurotoxicity.

Role and modulation of drug transporters in HIV-1 therapy

Current treatment of human immunodeficiency virus type-1 (HIV-1) infection involves a combination of antiretroviral drugs (ARVs) that target different stages of the HIV-1 life cycle. This strategy is commonly referred to as highly active antiretroviral therapy (HAART) or combined antiretroviral therapy (cART). Membrane-associated drug transporters expressed ubiquitously in mammalian systems play a crucial role in modulating ARV disposition during HIV-1 infection. Members of the ATP-binding cassette (ABC) and solute carrier (SLC) transporter superfamilies have been shown to interact with ARVs, including those that are used as part of first-line treatment regimens. As a result, the functional expression of drug transporters can influence the distribution of ARVs at specific sites of infection. In addition, pathological factors related to HIV-1 infection and/or ARV therapy itself can alter transporter expression and activity, thus further contributing to changes in ARV disposition and the effectiveness of HAART. This review summarizes current knowledge on the role of drug transporters in regulating ARV transport in the context of HIV-1 infection.

Maraviroc-intensified combined antiretroviral therapy improves cognition in virally suppressed HIV-associated neurocognitive disorder

OBJECTIVE

To investigate whether intensification of combined antiretroviral therapy (cART) with the CC chemokine receptor type 5 (CCR5) entry inhibitor maraviroc leads to improvement in global neurocognitive functioning in virally suppressed men with HIV-associated neurocognitive disorder (HAND).

DESIGN

Prospective, double observer-blinded, open-label pilot randomized-controlled trial. Participants were randomized to remain on their existing cART regimen (control arm; n = 8) or receive maraviroc-intensification (maraviroc arm; n = 9).

METHODS

Participants completed a five-domain neuropsychological battery at baseline, 6- and 12-month visits. Raw scores were transformed into age-corrected z-scores and averaged into a global z-score. Single voxel (H)-magnetic resonance spectroscopy (MRS) major cerebral metabolite concentrations were collected at baseline and 12 months in the basal ganglia and frontal white matter and quantified using jMRUI. Neuroinflammatory biomarkers cerebrospinal fluid neopterin and β2-microglobulin were also measured.

RESULTS

Fourteen of the 17 participants completed the study: nine maraviroc arm and five control. We found medium to large effect sizes in favour of improved global neurocognitive performance in the maraviroc arm over time {arm*time interaction: P < 0.05; 6 month: [β=-0.10, standard error (SE)= 0.04, 90% confidence interval (90%CI)= -0.18,.03; P < 0.03] yielding a large effect-size d = 0.77 (90%CI = -0.19,1.71); 12 month: [β=-0.01; SE = 0.05; 90%CI = -0.09, 0.06; P < 0.77] yielding a moderate effect-size d = 0.55 (90%CI = -0.47,1.55)}. No treatment-related changes were detected for H-MRS metabolites or cerebrospinal fluid biomarkers.

CONCLUSION

This pilot study provides feasibility, tolerability, proof-of-concept and preliminary evidence for clinically relevant neurocognitive improvement in cART enhancement with maraviroc in virally suppressed HAND patients. Lack of concomitant brain metabolite and biomarker change may be related to complex dynamics of brain repair.

The Chronicity of HIV Infection Should Drive the Research Strategy of NeuroHIV Treatment Studies: A Critical Review

HIV infection has become a chronic illness when successfully treated with combined antiretroviral therapy (cART). The long-term health prognosis of aging with controlled HIV infection and HIV-associated neurocognitive disorder (HAND) remains unclear. In this review, we propose that, almost 20 years after the introduction of cART, a change in research focus is needed, with a greater emphasis on chronicity effects driving our research strategy. We argue that pre-emptive documentation of episodes of mild neurocognitive dysfunction is needed to determine their long-term prognosis. This strategy would also seek to optimally represent the entire HAND spectrum in therapeutic trials to assess positive and/or negative treatment effects on brain functions. In the first part of the paper, to improve the standard implementation of the Frascati HAND diagnostic criteria, we provide a brief review of relevant quantitative neuropsychology concepts to clarify their appropriate application for a non-neuropsychological audience working in HIV research and wanting to conduct randomized clinical trials on brain functions. The second part comprises a review of various antiretroviral drug classes and individual agents with respect to their effects on HAND, while also addressing the question of when cART should be initiated to potentially reduce HAND incidence. In each section, we use recent observational studies and randomized controlled trials to illustrate our perspective while also providing relevant statistical comments. We conclude with a discussion of the neuroimaging methods that could be combined with neuropsychological approaches to enhance the validity of HIV neurology (neuroHIV) treatment effect studies.

Maraviroc: a review of its use in HIV infection and beyond

The human immunodeficiency virus-1 (HIV-1) enters target cells by binding its envelope glycoprotein gp120 to the CD4 receptor and/or coreceptors such as C-C chemokine receptor type 5 (CCR5; R5) and C-X-C chemokine receptor type 4 (CXCR4; X4), and R5-tropic viruses predominate during the early stages of infection. CCR5 antagonists bind to CCR5 to prevent viral entry. Maraviroc (MVC) is the only CCR5 antagonist currently approved by the United States Food and Drug Administration, the European Commission, Health Canada, and several other countries for the treatment of patients infected with R5-tropic HIV-1. MVC has been shown to be effective at inhibiting HIV-1 entry into cells and is well tolerated. With expanding MVC use by HIV-1-infected humans, different clinical outcomes post-approval have been observed with MVC monotherapy or combination therapy with other antiretroviral drugs, with MVC use in humans infected with dual-R5- and X4-tropic HIV-1, infected with different HIV-1 genotype or infected with HIV-2. This review discuss the role of CCR5 in HIV-1 infection, the development of the CCR5 antagonist MVC, its pharmacokinetics, pharmacodynamics, drug–drug interactions, and the implications of these interactions on treatment outcomes, including viral mutations and drug resistance, and the mechanisms associated with the development of resistance to MVC. This review also discusses available studies investigating the use of MVC in the treatment of other diseases such as cancer, graft-versus-host disease, and inflammatory diseases.

Pharmacokinetics and pharmacodynamics of antiretrovirals in the central nervous system

HIV-positive patients may be effectively treated with highly active antiretroviral therapy and such a strategy is associated with striking immune recovery and viral load reduction to very low levels. Despite undeniable results, the central nervous system (CNS) is commonly affected during the course of HIV infection, with neurocognitive disorders being as prevalent as 20-50 % of treated subjects. This review discusses the pathophysiology of CNS infection by HIV and the barriers to efficacious control of such a mechanism, including the available data on compartmental drug penetration and on pharmacokinetic/pharmacodynamic relationships. In the reviewed articles, a high variability in drug transfer to the CNS is highlighted with several mechanisms as well as methodological issues potentially influencing the observed results. Nevirapine and zidovudine showed the highest cerebrospinal fluid (CSF) to plasma ratios, although target concentrations are currently unknown for the CNS. The use of the composite CSF concentration effectiveness score has been associated with better virological outcomes (lower HIV RNA) but has been inconsistently associated with neurocognitive outcomes. These findings support the CNS effectiveness of commonly used highly antiretroviral therapies. The use of antiretroviral drugs with increased CSF penetration and/or effectiveness in treating or preventing neurocognitive disorders however needs to be assessed in well-designed prospective studies.

HIV-1 induces cytoskeletal alterations and Rac1 activation during monocyte-blood-brain barrier interactions: modulatory role of CCR5

Background

Most HIV strains that enter the brain are macrophage-tropic and use the CCR5 receptor to bind and infect target cells. Because the cytoskeleton is a network of protein filaments involved in cellular movement and migration, we investigated whether CCR5 and the cytoskeleton are involved in endothelial-mononuclear phagocytes interactions, adhesion, and HIV-1 infection.

Results

Using a cytoskeleton phospho-antibody microarray, we showed that after co-culture with human brain microvascular endothelial cells (HBMEC), HIV-1 infected monocytes increased expression and activation of cytoskeleton-associated proteins, including Rac1/cdc42 and cortactin, compared to non-infected monocytes co-cultured with HBMEC. Analysis of brain tissues from HIV-1-infected patients validated these findings, and showed transcriptional upregulation of Rac1 and cortactin, as well as increased activation of Rac1 in brain tissues of HIV-1-infected humans, compared to seronegative individuals and subjects with HIV-1-encephalitis. Confocal imaging showed that brain cells expressing phosphorylated Rac1 were mostly macrophages and blood vessels. CCR5 antagonists TAK-799 and maraviroc prevented HIV-induced upregulation and phosphorylation of cytoskeleton-associated proteins, prevented HIV-1 infection of macrophages, and diminished viral-induced adhesion of monocytes to HBMEC. Ingenuity pathway analysis suggests that during monocyte-endothelial interactions, HIV-1 alters protein expression and phosphorylation associated with integrin signaling, cellular morphology and cell movement, cellular assembly and organization, and post-translational modifications in monocytes. CCR5 antagonists prevented these HIV-1-induced alterations.

Conclusions

HIV-1 activates cytoskeletal proteins during monocyte-endothelial interactions and increase transcription and activation of Rac1 in brain tissues. In addition to preventing macrophage infection, CCR5 antagonists could diminish viral-induced alteration and phosphorylation of cytoskeletal proteins, monocyte adhesion to the brain endothelium and viral entry into the central nervous system.

HIV-associated neurocognitive disorders: perspective on management strategies

Potent combination antiretroviral therapy (ART) has resulted in dramatic improvements in AIDS-associated morbidity and mortality. Although combination ART has resulted in a significant reduction in HIV-associated dementia, the most severe of the HIV-associated neurocognitive disorders (HAND), the overall prevalence of HAND among this population is estimated at 40%. It has been recognized that the central nervous system (CNS) serves as a reservoir for HIV, and neuronal damage begins at the time of acute infection and persists due to chronic infection of microglial and perivascular macrophages. Although combination ART has resulted in virologic control in the plasma compartment, virologic breakthrough can potentially ensue within the CNS compartment due to limited ART drug exposure. The purpose of this review is to discuss the definition, clinical spectrum, and risk factors associated with HAND, review the pathogenesis of HAND, and address the pharmacologic challenges associated with ART drug exposure in the CNS compartment.

Antiretroviral bioanalysis methods of tissues and body biofluids

Research in the many areas of HIV treatment, eradication and prevention has necessitated measurement of antiretroviral (ARV) concentrations in nontraditional specimen types. To determine the knowledgebase of critical details for accurate bioanalysis, a review of the literature was performed and summarized. Bioanalytical assays for 31 ARVs, including metabolites, were identified in 205 publications measuring various tissues and biofluids. 18 and 30% of tissue or biofluid methods, respectively, analyzed more than one specimen type; 35-37% of the tissue or biofluid methods quantitated more than one ARV. 20 and 76% of tissue or biofluid methods, respectively, were used for the analysis of human specimens. HPLC methods with UV detection predominated, but chronologically MS detection began to surpass. 40% of the assays provided complete intra- and inter-assay validation data, but only 9% of publications provided any stability data with even less for the prevalent ARV in treatments.

Neuroprotective maraviroc monotherapy in simian immunodeficiency virus-infected macaques: reduced replicating and latent SIV in the brain

OBJECTIVE

HIV-associated neurocognitive deficits remain a challenge despite suppressive combined antiretroviral therapy. Given the association between HIV-induced central nervous system (CNS) disease and replication of HIV in immune-activated macrophages, CCR5 antagonists may attenuate CNS disease by modulating inflammatory signaling and by limiting viral replication.

DESIGN

To establish whether initiating CCR5 inhibition during early infection altered CNS disease progression, outcomes were compared between simian immunodeficiency virus (SIV)-infected macaques treated with maraviroc (MVC) versus untreated SIV-infected macaques.

METHODS

Six SIV-infected rhesus macaques were treated with MVC monotherapy for 5 months beginning 24 days postinoculation; 22 SIV-infected animals served as untreated controls. SIV RNA levels in plasma, cerobrospinal fluid, and brain, and CNS expression of TNFα and CCL2 were measured by qRT-PCR. Immunostaining for CD68 and amyloid precursor protein in the brain was measured by image analysis. Plasma sCD163 was measured by ELISA.

RESULTS

SIV RNA and proviral DNA levels in brain were markedly lower with MVC treatment, demonstrating CCR5 inhibition reduces CNS replication of SIV and may reduce the CNS latent viral reservoir. MVC treatment also lowered monocyte and macrophage activation, represented by CNS CD68 immunostaining and plasma sCD163 levels, and reduced both TNFα and CCL2 RNA expression in brain. Treatment also reduced axonal amyloid precursor protein immunostaining to levels present in uninfected animals, consistent with neuroprotection.

CONCLUSION

CCR5 inhibitors may prevent neurologic disorders in HIV-infected individuals by reducing inflammation and by limiting viral replication in the brain. Furthermore, CCR5 inhibitors may reduce the latent viral reservoir in the CNS. Adding CCR5 inhibitors to combined antiretroviral regimens may offer multiple neuroprotective benefits.

Clinical studies with chemokine receptor-5 (CCR5)-inhibitors

PURPOSE OF REVIEW

To summarise recently published clinical studies of chemokine receptor-5 (CCR5)-blockers, including the small-molecule blocker, maraviroc (MVC) and CCR5-monoclonal antibodies for HIV. MVC may have immunomodulating properties through CCR5-blockade. MVC appears well tolerated and penetrates the central nervous system. For these reasons, MVC is being investigated in immunodiscordance, prevention of IRIS and in HCV-HIV co-infection. Novel techniques allow tropism assignment via sequencing of proviral DNA; this testing platform is being utilised in MVC switch studies in those with HIV viraemia below the level of quantification. MVC is being utilised in regimen intensification studies for HIV associated neurocognitive disease.

RECENT FINDINGS

MVC has no anti-inflammatory activity in rheumatoid arthritis. MVC appears well tolerated in hepatitis virus co-infected patients and MVC-intensification in HCV-HIV co-infection suggests a favourable impact on liver fibrosis. Early pilot data suggests MVC intensification may have functional benefit in the CNS. There is a growing body of data on tropism testing using proviral DNA; this technology is being utilised in MVC switch studies. CCR5-monoclonal antibodies administered subcutaneously are promising in Phase II development.

SUMMARY

The place of MVC as an anti-HIV drug in the switch setting and as an immunomodulator is yet to be fully determined.

CSF penetration by antiretroviral drugs

Severe HIV-associated neurocognitive disorders (HAND), such as HIV-associated dementia, and opportunistic CNS infections are now rare complications of HIV infection due to comprehensive highly active antiretroviral therapy (HAART). By contrast, mild to moderate neurocognitive disorders remain prevalent, despite good viral control in peripheral compartments. HIV infection seems to provoke chronic CNS injury that may evade systemic HAART. Penetration of antiretroviral drugs across the blood-brain barrier might be crucial for the treatment of HAND. This review identifies and evaluates the available clinical evidence on CSF penetration properties of antiretroviral drugs, addressing methodological issues and discussing the clinical relevance of drug concentration assessment. Although a substantial number of studies examined CSF concentrations of antiretroviral drugs, there is a need for adequate, well designed trials to provide more valid drug distribution profiles. Neuropsychological benefits and neurotoxicity of potentially CNS-active drugs require further investigation before penetration characteristics will regularly influence therapeutic strategies and outcome.

Lower than expected maraviroc concentrations in cerebrospinal fluid exceed the wild-type CC chemokine receptor 5-tropic HIV-1 50% inhibitory concentration

To measure maraviroc total cerebrospinal fluid (CSF) concentrations and compare them with total and unbound plasma concentrations. Total maraviroc was measured by reverse-phase high-performance liquid chromatography with tandem mass spectrometry, whereas ultrafiltration was used for unbound maraviroc. Maraviroc was detected in all nine CSF/plasma pairs with a median CSF total concentration of 2.4 ng/ml. CSF concentrations exceeded the 50% inhibitory concentration of wild-type CC chemokine receptor 5-tropic HIV-1 in all specimens. CSF concentrations are lower than expected based on plasma concentrations and physicochemical characteristics. Unbound maraviroc plasma concentrations may be informative in estimating concentrations in CSF.

The chemokine receptor CCR5 in the central nervous system

The expression and the role of the chemokine receptor CCR5 have been mainly studied in the context of HIV infection. However, this protein is also expressed in the brain, where it can be crucial in determining the outcome in response to different insults. CCR5 expression can be deleterious or protective in controlling the progression of certain infections in the CNS, but it is also emerging that it could play a role in non-infectious diseases. In particular, it appears that, in addition to modulating immune responses, CCR5 can influence neuronal survival. Here, we summarize the present knowledge about the expression of CCR5 in the brain and highlight recent findings suggesting its possible involvement in neuroprotective mechanisms.