Monocytes transmigrating to the brain play a central role in HIV neuropathology. We hypothesized that the continued existence of neurocognitive impairment (NCI) despite potent antiretroviral (ARV) therapy is mediated by the inability of such therapy to control this monocyte/macrophage reservoir.
Cross-sectional and longitudinal analyses were conducted within a prospectively enrolled cohort. We devised a monocyte efficacy (ME) score based on the anticipated effectiveness of ARV medications against monocytes/macrophages using published macrophage in vitro drug efficacy data. We examined, within an HIV neurocognitive database, its association with composite neuropsychological test scores (NPZ8) and clinical cognitive diagnoses among subjects on stable ARV medications unchanged for >6 months prior to assessment.
Among 139 subjects on ARV therapy, higher ME score correlated with better NPZ8 performance (r=0.23, P<0.01), whereas a score devised to quantify expected penetration effectiveness of ARVs into the brain (CPE score) did not (r=0.12, P=0.15). In an adjusted model (adjusted r(2)=0.12), ME score (β=0.003, P=0.02), CD4(+) T-cell nadir (β=0.001, P<0.01) and gender (β=-0.456, P=0.02) were associated with NPZ8, whereas CPE score was not (β=0.003, P=0.94). A higher ME score was associated with better clinical cognitive status (P<0.01). With a range of 12.5-433.0 units, a 100-unit increase in ME score resulted in a 10.6-fold decrease in the odds of a dementia diagnosis compared with normal cognition (P=0.01).
ARV efficacy against monocytes/macrophages correlates with cognitive function in HIV-infected individuals on ARV therapy within this cohort. If validated, efficacy against monocytes/macrophages may provide a new target to improve HIV NCI.
"cART regimens with higher monocyte efficacy scores more effectively inhibited the in vitro infection of monocytes and macrophages as compared to treatments with lower scores. HIV seropositive people receiving antiretroviral regimens with lower monocyte efficacy scores had a significantly higher likelihood of cognitive impairment . This occurred even in individuals who had undetectable plasma viral loads. "
[Show abstract][Hide abstract] ABSTRACT: HIV infected people are living longer due to the success of combined antiretroviral therapy (cART).However, greater than 40-70% of HIV infected individuals develop HIV associated neurocognitive disorders (HAND) that continues to be a major public health issue. While cART reduces peripheral virus, it does not limit the low level, chronic neuroinflammation that is ongoing during the neuropathogenesis of HIV. Monocyte transmigration across the blood brain barrier (BBB), specifically that of the mature CD14+CD16+ population that is highly susceptible to HIV infection, is critical to the establishment of HAND as these cells bring virus into the brain and mediate the neuroinflammation that persists, even if at low levels, despite antiretroviral therapy. CD14+CD16+ monocytes preferentially migrate into the CNS early during peripheral HIV infection in response to chemotactic signals, including those from CCL2 and CXCL12. Once within the brain, monocytes differentiate into macrophages and elaborate inflammatory mediators. Monocytes/macrophages constitute a viral reservoir within the CNS and these latently infected cells may perpetuate the neuropathogenesis of HIV. This review will discuss mechanisms that mediate transmigration of CD14+CD16+ monocytes across the BBB in the context of HIV infection, the contribution of these cells to the neuropathogenesis of HIV, and potential monocyte/macrophage biomarkers to identify HAND and monitor its progression.
Current HIV Research 05/2014; DOI:10.2174/1570162X12666140526114526 · 1.76 Impact Factor
"Since macrophage and microglial cells are the primary cells within the CNS productively infected by HIV, recent investigation has focused on the role of antiretroviral penetration into monocytes, cells which may serve as circulating precursors to these cellular reservoirs within the CNS and which have been found by some investigators to be linked to presence of HAND [78, 79]. Putative ability of individual antiretrovirals to affect HIV replication within monocyte-lineage cells has been quantitated as a monocyte efficacy (ME) score, and one study employing summed ME scores from drug regimens found this to be a closer predictor of neuropsychological performance than CPE . Ideally, randomized clinical trials of higher as compared to lower CPE and ME regimens would provide the best data to indicate whether such indices should be taken into account in treatment of HIV infected individuals and specifically those meeting criteria for HAND. "
[Show abstract][Hide abstract] ABSTRACT: The spectrum of HIV-associated neurocognitive disorder (HAND) has been dramatically altered in the setting of widely available effective antiretroviral therapy (ART). Once culminating in dementia in many individuals infected with HIV, HAND now typically manifests as more subtle, though still morbid, forms of cognitive impairment in persons surviving long-term with treated HIV infection. Despite the substantial improvement in severity of this disorder, the fact that neurologic injury persists despite ART remains a challenge to the community of patients, providers and investigators aiming to optimize quality of life for those living with HIV. Cognitive dysfunction in treated HIV may reflect early irreversible CNS injury accrued before ART is typically initiated, ongoing low-level CNS infection and progressive injury in the setting of ART, or comborbidities including effects of treatment which may confound the beneficial reduction in viral replication and immune activation effected by ART.
Current HIV/AIDS Reports 07/2013; 10(3). DOI:10.1007/s11904-013-0171-y · 3.80 Impact Factor
"Additionally, the relationship between in vitro observations and in vivo dynamics is not fully elucidated. Much evidence exists to support the existence of HIV-1 replication in macrophage/ macrophage-like cells in vivo       , including a recent report from Deleage et al., and confirmed the presence of HIV-1 in macrophages within seminal vesicles of patients on effective highly active antiretroviral therapy (HAART) . Correspondingly, a variety of studies have presented evidence that monocytes harbor productive viral replication in patients receiving HAART  , with other reports demonstrating that CD16 + monocytes, a subset of monocytes , are a source of HIV-1 permissive cells that preferentially harbor HIV-1 in vivo . "
[Show abstract][Hide abstract] ABSTRACT: Macrophages are ubiquitous and represent a significant viral reservoir for HIV-1. Macrophages are nondividing, terminally differentiated cells, which have a unique cellular microenvironment relative to actively dividing T lymphocytes, all of which can impact HIV-1 infection/replication, design of inhibitors targeting viral replication in these cells, emergence of mutations within the HIV-1 genome, and disease progression. Scarce dNTPs drive rNTP incorporation into the proviral DNA in macrophages but not lymphocytes. Furthermore, the efficacy of a ribose-based inhibitor that potently inhibits HIV-1 replication in macrophages, has prompted a reconsideration of the previously accepted dogma that 2'-deoxy-based inhibitors demonstrate effective inhibition of HIV-1 replication. Additionally, higher levels of dUTP and rNTP incorporation in macrophages, and lack of repair mechanisms relative to lymphocytes, provide a further mechanistic understanding required to develop targeted inhibition of viral replication in macrophages. Together, the concentrations of dNTPs and rNTPs within macrophages comprise a distinctive cellular environment that directly impacts HIV-1 replication in macrophages and provides unique insight into novel therapeutic mechanisms that could be exploited to eliminate virus from these cells.
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