Impact of sleep deprivation on neurocognition and inflammation in rhesus macaques.

Sleep deprivation in humans is associated with both cognitive impairment and immune dysregulation. An animal model of neuropathogenesis may provide insight to understand the effects of sleep deprivation on the brain. Human neurocognition is more closely mirrored by nonhuman primates (NHP) than other animals. As such, we developed an NHP model to assess the impact of sleep deprivation on neurocognition and markers of systemic immune activation. Six male rhesus macaques underwent three rounds of sleep deprivation (48 h without sleep) at days 0, 14, and 28. We performed domain specific cognitive assessments using the Cambridge Neuropsychological Test Automated Battery (CANTAB) via a touch screen before and after 24 and 48 h of sleep deprivation. Immune activation markers were measured in the blood by multiplex assay and flow cytometry. Although we observed variability in cognitive performance between the three rounds of sleep deprivation, cognitive impairments were identified in all six animals. We noted more cognitive impairments after 48 h than after 24 h of sleep deprivation. Following 48 h of sleep deprivation, elevations in markers of immune activation in the blood were observed in most animals. The observed impairments largely normalized after sleep. The co-occurrence of systemic immune alterations and cognitive impairment establishes this model as useful for studying the impact of sleep deprivation on neurobehavior and immune perturbations in rhesus macaques.

Neurocognitive impact of Zika virus infection in adult rhesus macaques.

BACKGROUND: Zika virus (ZIKV) is a mosquito-transmitted flavivirus that affects many regions of the world. Infection, in utero, causes microcephaly and later developmental and neurologic impairments. The impact of ZIKV infection on neurocognition in adults has not been well described. The objective of the study was to assess the neurocognitive impact of ZIKV infection in adult rhesus macaques. METHODS: Neurocognitive assessments were performed using the Cambridge Neuropsychological Test Automated Battery (CANTAB) via a touch screen and modified Brinkman Board before and after subcutaneous ZIKV inoculation. Immune activation markers were measured in the blood and cerebral spinal fluid (CSF) by multiplex assay and flow cytometry. RESULTS: All animals (N = 8) had detectable ZIKV RNA in plasma at day 1 post-inoculation (PI) that peaked at day 2 PI (median 5.9, IQR 5.6-6.2 log10 genome equivalents/mL). In all eight animals, ZIKV RNA became undetectable in plasma by day 14 PI, but persisted in lymphoid tissues. ZIKV RNA was not detected in the CSF supernatant at days 4, 8, 14 and 28 PI but was detected in the brain of 2 animals at days 8 and 28 PI. Elevations in markers of immune activation in the blood and CSF were accompanied by a reduction in accuracy and reaction speed on the CANTAB in the majority of animals. CONCLUSIONS: The co-occurrence of systemic and CSF immune perturbations and neurocognitive impairment establishes this model as useful for studying the impact of neuroinflammation on neurobehavior in rhesus macaques, as it pertains to ZIKV infection and potentially other pathogens.

TLR7 agonist, N6-LS and PGT121 delayed viral rebound in SHIV-infected macaques after antiretroviral therapy interruption.

Toll-like receptor 7 (TLR7) agonist and PGT121 (broadly neutralizing antibody, bnAb) administration previously delayed viral rebound and induced SHIV remission. We evaluated the impact of GS-986 (TLR7 agonist) and dual bnAbs on viral rebound after antiretroviral therapy (ART) interruption. Rhesus macaques inoculated with SHIV-1157ipd3N4 were initiated on daily suppressive ART from Day 14 post SHIV inoculation. Active arm animals (n = 8) received GS-986, N6-LS and PGT121 after plasma viral suppression, starting from week 14. GS-986 induced immune activation and SHIV-specific T cell responses but not viral expression in all the active arm animals. After ART interruption, median time to viral rebound was 6 weeks in the active and 3 weeks in the control arm (p = 0.024). In this animal model, the administration of the combination of GS-986 and dual bnAbs was associated with a modest delay in viral rebound. This strategy should be further evaluated to better understand the underlying mechanisms for the induction of virus-specific immune responses and delay in viral rebound.

Impact of analytical treatment interruption on the central nervous system in a simian-HIV model.

OBJECTIVE(S): Analytical treatment interruption (ATI) studies are often used to evaluate potential HIV cure strategies. This study was conducted to determine the impact of ATI on simian-HIV (SHIV) infection in the central nervous system. DESIGN: Animal study. METHODS: Nine rhesus macaques were inoculated with SHIV-1157ipd3N4. Antiretroviral therapy (ART) was administered from week 2 to 18. At week 18, four animals were euthanized (no-ATI-group) and five underwent ATI (ATI-group) and were euthanized at 12 weeks post viral rebound. Plasma and cerebrospinal fluid (CSF) SHIV-RNA, markers of inflammation and brain CD3+, CD68+/CD163+ and RNA+ cells were measured. RESULTS: All nine animals were SHIV-infected, with median pre-ART plasma and CSF SHIV-RNA of 6.2 and 3.6 log10copies/ml. Plasma and CSF IL-15, monocyte chemoattractant protein-1, IFN-γ-induced protein-10 and neopterin increased postinfection. ART initiation was associated with rapid and complete suppression of plasma viremia and reductions in plasma and CSF IL-15, IFN-γ-induced protein-10, neopterin and CSF monocyte chemoattractant protein-1. Median time to plasma viral rebound was 21 days post-ATI. At 12 weeks postrebound, CSF SHIV-RNA was undetectable and no increases in plasma and CSF markers of inflammation were found. Higher numbers of CD3+ and CD68+/CD163+ cells were seen in the brains of 3/5 and 1/5 animals, respectively, in the ATI-group when compared with no-ATI-group. SHIV-RNA+ cells were not identified in the brain in either group post-ATI. CONCLUSION: ATI in macaques that initiated ART during early SHIV-1157ipd3N4 infection was associated with mild, localized T-cell infiltrate in the brain without detectable SHIV-RNA in the brain or CSF, or elevation in CSF soluble markers of inflammation.

Central Nervous System Inflammation and Infection during Early, Nonaccelerated Simian-Human Immunodeficiency Virus Infection in Rhesus Macaques.

Studies utilizing highly pathogenic simian immunodeficiency virus (SIV) and simian-human immunodeficiency virus (SHIV) have largely focused on the immunopathology of the central nervous system (CNS) during end-stage neurological AIDS and SIV encephalitis. However, this may not model pathophysiology in earlier stages of infection. In this nonaccelerated SHIV model, plasma SHIV RNA levels and peripheral blood and colonic CD4+ T cell counts mirrored early human immunodeficiency virus (HIV) infection in humans. At 12 weeks postinfection, cerebrospinal fluid (CSF) detection of SHIV RNA and elevations in IP-10 and MCP-1 reflected a discrete neurovirologic process. Immunohistochemical staining revealed a diffuse, low-level CD3+ CD4- cellular infiltrate in the brain parenchyma without a concomitant increase in CD68/CD163+ monocytes, macrophages, and activated microglial cells. Rare SHIV-infected cells in the brain parenchyma and meninges were identified by RNAScope in situ hybridization. In the meninges, there was also a trend toward increased CD4+ infiltration in SHIV-infected animals but no differences in CD68/CD163+ cells between SHIV-infected and uninfected control animals. These data suggest that in a model that closely recapitulates human disease, CNS inflammation and SHIV in CSF are predominantly mediated by T cell-mediated processes during early infection in both brain parenchyma and meninges. Because SHIV expresses an HIV rather than SIV envelope, this model could inform studies to understand potential HIV cure strategies targeting the HIV envelope.IMPORTANCE Animal models of the neurologic effects of HIV are needed because brain pathology is difficult to assess in humans. Many current models focus on the effects of late-stage disease utilizing SIV. In the era of antiretroviral therapy, manifestations of late-stage HIV are less common. Furthermore, new interventions, such as monoclonal antibodies and therapeutic vaccinations, target HIV envelope. We therefore describe a new model of central nervous system involvement in rhesus macaques infected with SHIV expressing HIV envelope in earlier, less aggressive stages of disease. Here, we demonstrate that SHIV mimics the early clinical course in humans and that early neurologic inflammation is characterized by predominantly T cell-mediated inflammation accompanied by SHIV infection in the brain and meninges. This model can be utilized to assess the effect of novel therapies targeted to HIV envelope on reducing brain inflammation before end-stage disease.

CD4+ Cell infiltration into subcutaneous adipose tissue is not indicative of productively infected cells during acute SHIV infection.

Limited longitudinal data exist on the effect of HIV on adipose tissue (AT). We found an increase in CD4+ cells and detectable SHIV-RNA in AT during acute SHIV infection. SHIV-RNA+ cells were rare, suggesting that AT is unlikely to be a major source of productively infected cells in SHIV infection.