Cristian L. Achim, MD, University of Bucharest, PhD, University of California San Diego - US grants

DESCRIPTION (Adapted from applicant's abstract): A significant number of AIDS patients develop a progressive CNS disorder with motor and cognitive deficits called AIDS dementia complex (ADC). ADC has been linked to increasing CNS viral burden, but how HIV mediates central nervous system (CNS) damage is not known. Our central hypothesis is that increasing CNS viral burden is the primary cause of ADC. Disruption of either the physical blood brain barrier or its physiological functions may play a direct role in the progression of CNS damage. As the BBB plays a pivotal role in the entry of HIV into the CNS, it is a logical target for measures designed to prevent ADC. We propose to examine the role of the BBB in ADC by using human autopsy material and two different in vivo models. We have available a bank of frozen and fixed CNS autopsy tissues from approximately 500 AIDS patients with premortem neurologic symptoms ranging from asymptomatic to severe dementia. The in vivo models will allow us to examine the temporal sequence of BBB abnormalities and to assess the efficacy of treatment strategies. The first model uses human fetal CNS aggregates grafted into the brain of SCID mice, and the second uses ts-1, a neurotropic murine leukemia virus (MuLV), as a model of chronic retroviral encephalitis. In SA#1 we will define the temporal sequence of morphologic and functional changes of the BBB. Ultrastructural studies will examine morphologic abnormalities, and immunocytochemistry with laser confocal microscopy will assess the status of endothelial transport proteins. Ingress of macrophages into the CNS may be the key development in the onset of ADC and is probably regulated by adhesion molecules on the BBB. SA#2 will characterize the presence and distribution of adhesion molecules on the BBB. Little is known about adhesion molecules necessary for the trafficking of monocytes/ macrophages into the CNS in retroviral infected brains. SA#3 will examine immune cell trafficking into the CNS. Using our SCID model the kinetics of CNS penetration by HIV-infected and non-infected T-cells and monocytes will be studied. Finally, the prevention of ADC is the ultimate aim in all of these studies. SA#4 will examine the effect of therapeutic intervention on the BBB and the onset of retroviral encephalitis. We believe that by using these two very different models and by direct integration of findings with AIDS autopsy material, we are in a unique position to delineate important characteristics of the BBB in ADC and the potential for therapeutic intervention.

DESCRIPTION (adapted from the Abstract): Approximately one quarter of patients with the acquired immunodeficiency syndrome (AIDS) develop neurologic symptoms attributable to human immunodeficiency virus, Type 1 (HIV) infection within the brain. Recent studies have shown that all patients with HIV dementia have at autopsy neuropathologic changes consistent with HIV encephalitis. Other studies suggest that HIV- associated neurologic damage may be mediated by immune factors secreted by activated/infected macrophages in the central nervous system (CNS). The Principal Investigator proposes to develop an in vivo system in which viral infection of developing human brain tissue can be studied without many of the in vitro difficulties. In this model dissociated human brain tissue is grown in vitro as a single cell suspension in serum free media; fetal neural cells aggregate and form "brain microspheres" which are then transplanted into the crania of severe combined immunodeficiency (SCID) mice. Pilot studies suggest that brain microspheres injected in the fat pad of SCID mice differentiate and survive for several months in vivo. Study of these grafts shows the presence of functional neural cells and vascular organization suggesting a blood brain barrier. (When brain microspheres are co-cultured in vitro with HIV-infected human macrophages, virus is detected inside the human neural tissue grafts; when the brain microspheres are implanted into a CNS environment, differentiation [i.e., synaptogenesis] is promoted within the graft.) Pilot studies suggest that human fetal brain microspheres can be successfully injected in the crania of SCID mice and surviving grafts can be recovered at different time points post inoculation. In the proposed research, all human grafts will be characterized in vitro prior to implantation. In vivo, grafts will be assessed for neuronal survival and differentiation, development of a blood brain barrier, and CNS macrophage/ microglia activation. Human grafts containing HIV-infected macrophages will be assessed for viral burden, production of macrophage activation factors, and degeneration (i.e., neuronal and glial pathology). Neuropathologic changes found in HIV-infected grafts will be then compared to the findings in autopsy studies of patients with HIV encephalitis. In this human fetal brain/SCID mouse model, both qualitative and quantitative measurements of viral and immune factors can be performed, neuronal differentiation can be studied, and the perturbations caused by addition of HIV-infected macrophages can then be temporally monitored to help elucidate the pathogenesis of neurologic damage.

Chemokines and their receptors have been recently implicated as important factors in the progress of HIV infection. A systematic characterization of their distribution within the brain is essential to understand changes in their expression during HIV encephalitis (HIVE). In S.A. number 1 we will compare abundance and distribution of chemokines and their receptors in the brain of AIDS patients who died with various degrees of HIVE and determine the relationship with viral burden. Levels of chemokine and receptor gene expression and localization will be assessed by quantitative reverse-transcription-PCR (QRT-PCR). Cellular localization will be determined by double immunofluorescent laser confocal microscopy (IFLCM). Brain viral burden will be measured by new quantitative HIV mRNA assays and PCR for proviral genes. In vitro, HIV infection of human macrophages is chronic and productive. Using fetal and postnatal microglial cultures and various viral stains, in SA number 2 we will study mechanisms of viral spread within the brain macrophage cell population and try to clarify the inconsistencies reported in previous studies regarding the role played by the newly described co-receptors. Gene expression and cellular distribution of chemokine receptors will be analyzed by RT-PCR, immunostaining and receptor binding studies using fluorescent labeled ligands. HIV infection of microglia will be compared to monocyte derived macrophage (MDM) cultures using IFLCM, ELISA and immuno-EM for HIV proteins and RT- PCR for HIV genes. To identify other genes potentially involved in the spread of HIV infection within brain macrophages we propose to use a recently developed technique called mRNA differential display analysis. In SA number 3 we will try to block infection using chemokine receptor ligands and treatments with new antiretroviral drugs. In addition to natural and synthetic chemokine molecules, we will test combinations of nucleoside analogs and protease inhibitors in MDM and microglial cultures infected with HIV. The neurotoxicity (measured by decreased neuronal survival and differentiation) of various treatments will be tested in vitro in HIV infected microglia or MDM co-cultured with uninfected neuroglial (mixed neuronal and astrocytic) fetal cells. The relevance of the results from autopsy studies regarding the role played by various new co-receptors will be tested in an in vitro model based on primary cultures of human neuroglia and macrophages. Comparison of autopsy and in vitro data will identify important mechanisms of disease that can be subjected to therapeutic interventions. We believe that the recently proposed HIV co-receptors are important but they are not unique or sufficient to explain the HIV spread in the brain macrophage population. We also hypothesize that chemokine receptors expressed on human (non-macrophage) neuroglia may mediate neurotoxicity in HIVE and, consequently, the proposed treatments with ligands may have to be carefully assessed.

DESCRIPTION (provided by applicant): This is a revised proposal of the R21 MH072529-01 grant. All three reviewers agreed that the proposed studies are significant and innovative and may provide additional information on new mechanisms of disease but there were concerns regarding the weak clinical studies, insufficient number of HIV patients on HAART and Dr. Becker's contribution to this project. We responded to the criticisms and re-designed the clinical study (see our new Introduction). In recent years, human immunodeficiency virus (HIV) positive patients under highly active anti-retroviral therapy (HAART) regimens show a markedly improved general clinical status. It is now believed that the more aggressive antiviral therapies could have a long-term impact on the brain. We propose that increased longevity combined with a prolonged hyper-insulinemic state in long-term survivors on HAART may increase their risk of developing beta-amyloid (Abeta) deposition in the brain. In a pilot study of 162 cases, using immunocytochemistry on autopsy brain tissues, we found abundant beta-amyloid (Abeta) in the brains of HIV patients. A new positron emission tomography (PET) ligand developed at the University of Pittsburgh (PIB) can be used to test our hypothesis in vivo. SA#1: Complete a cross-sectional analysis of Abeta deposition in AIDS patients using a novel-PET ligand (PIB). Evaluate the effects of age and length of HAART on Abeta deposition. SA#2: Study the regional and cellular distribution of Abeta in autopsy brain tissues from HIV patients and controls. We propose that PET imaging may detect early signs of brain degeneration in HIV infected patients on HAART and possibly monitor the brain pathology associated with it. Since the incidence of minor cognitive impairment will probably increase, studies of Aa as a pathogenic factor will be useful in designing future NeuroAIDS studies.

[unreadable] DESCRIPTION (provided by applicant): Chronic neuropsychologic impairment (NPI) is a major complication in HIV infected long-term survivors on antiviral therapy (HAART). The pathogenesis is still unknown but likely candidates are: neurotoxic viral proteins; pharmacologic side effects; behavioral risk factors (e.g. drug abuse); chronic inflammation accompanied by neuroglial activation; the patient genetic background potentially modulating the metabolic and endocrinologic response to infection; age; gender; and also specific opportunistic pathologies. We have now identified a unique patient cohort at the Victor Babes Hospital (VBH) in Bucharest that may help in deciphering some of the specific NP risk factors associated with long term HIV infection. These patients are uniquely qualified for a longitudinal study: they form a highly homogenous cohort (average 18 y. o.) with similar viral strain infection (clade F), HAART regimen (approx. 7 years), and genetic background. We will assemble a cohort of 75 subjects (25 HIV+ with NPI, 25 HIV+ without NPI, and 25 HIV-) that will be studied for 2 years through regular neuromedical and NP exams and clinical laboratory evaluations of serologic and cerebrospinal fluid (CSF) markers of disease. To measure NPI we will use a test battery developed at the HIV Neurobehavioral Research Center (HNRC) at UC San Diego. Specific Aim #1: Demonstrate the cross-cultural applicability in Romania of a comprehensive neuropsychological (NP) test battery that has been extensively validated for detecting and characterizing neurobehavioral effects of HIV-1 infection in the U.S. Specific Aim #2: Identify comorbid factors in the Romanian young adults with HIV and compare them to the degree of NPI. Specific Aim #3: Characterize the neurotoxic potential of the Romanian clade F HIV and its susceptibility to antiviral treatments. This project will demonstrate feasibility and will help develop an infrastructure to perform neurobehavioral and virological studies in Romania, where no systematic studies of the neurocognitive manifestations of HIV-1 have been performed. The Romanian cohort could provide a unique insight in the future of HIV- associated NPI in long term-survivors on HAART. [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): This is a revised submission of our developmental grant (R21) proposing to study the association between immunophilins (IP) and markers of neurodegeneration in HIV infected patients and test the hypothesis that IP ligand (IPL) treatments may protect against HIV-associated axonal degeneration mediated by chemokines. We will characterize the normal and pathologic distribution of the FKBP family of IP in autopsy brain tissues from HIV infected patients with cognitive impairment and controls. We will also use an in vitro experimental model based on human brain cell cultures to study the association between IP and the presynaptic apparatus and analyze the effects of IPL treatments on neuronal survival and differentiation in the presence of HIV infection and glial activation. Our understanding of the role played by immunophilins in response to chronic neuronal injury in the HIV infected brain may lead to identifying new early markers of disease. Furthermore, IP may represent excellent targets for therapeutic interventions. Current studies suggest that IP ligands are potent neuroprotective agents and some of them are already in clinical use. Project Summary We plan to study the function of a relatively new family of abundant brain proteins, called immunophilins (IP), that may be involved in the survival and normal function of neurons in HIV infected patients. Our understanding of the role played by immunophilins in response to chronic neuronal injury may lead to the early diagnosis of neuropsychiatric damage and potential therapeutic interventions in long term survivors with HIV. Current studies suggest that IP ligands are neuroprotective and some of them are already in clinical use in organ transplant patients. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Despite the introduction of highly active antiretroviral therapy (HAART), HIV associated neurocognitive disorder (HAND) remains a significant cause of morbidity. Previous work has demonstrated that HAND is related to the severity of HIV associated neurodegeneration. In preliminary microarray work we have noted that the gene expression of a number of proteins related to the innate immune system toll-like receptor (TLR) signaling pathway correlates strongly with HIV associated neurodegeneration, most significantly TLR3 and -4. We have further demonstrated that treatment of astrocytes with gp120 (Bal) resulted in an increase in expression of TLR4. In the current application we wish to examine the potential relationship between TLR3 and 4 gene expression and exposure to HIV. TLR3 and -4 expressions will be assessed initially in primary human neuroglial cultures exposed to supernatants taken from HIV infected (Bal and SF162) monocyte derived macrophages (MDMs). mRNA expression will be measured via quantitative real time polymerase chain reaction (qRT-PCR) with protein expression measured via immunoblot and immunohistochemistry (IHC). In the second part of this proposal we will investigate the effects of blocking TLR3 and -4 expressions on HIV associated neurotoxicity. Similar to specific aim 1 and using the data generated from this aim we will treat primary human neuronal cultures with supernatants from HIV infected (Bal and SF162) MDMs at concentrations and time-points shown to cause toxicity. This will be in the absence and presence of siRNA's to TLR3 and -4. We will then verify this knockdown using qRT-PCR and assess the effects of this on HIV neurotoxic effects. As a potential mechanism for TLR induced neurodegeneration we will assess GSK3b activity in a final set of experiments using ELISA and also the ability of specific GSK3b inhibitors A014418 and B6B30 to prevent or attenuate HIV associated neurotoxicity. Data generated from this proposal will provide a first step towards elucidating the mechanism by which TLR gene products result in HIV associated neurodegeneration and also identify potential novel targets for ameliorating this toxic process. PUBLIC HEALTH RELEVANCE The ability to reduce or prevent neuronal loss associated with HIV has the potential to prevent or attenuate the effects of HAND. The focus of this proposal is to further characterize the role of TLR 3 and 4 dysregulation in HIV associated neurodegeneration and contribution of GSK3b activity in regulating this mechanism. Inhibition of TLR 3 and 4 activity may present a possible way to prevent HIV associated neurodegeneration and therefore alleviate symptoms of HAND.

The overall aims of the Developmental Core (DC) are to encourage innovative preliminary work in neuroAIDS; to foster new investigators with targeted Developmental grant support to serve as a springboard for successful applications for independent NIH funding; and within the interdisciplinary context of the HNRC, to help train the next generation of scientists in collarborative research essential for advancement of the field, in the current funding cycle, the Developmental Core has awarded 15 developmental grants, all encompassing promising new directions in neuroAIDS research, to students, postdoctoral fellows, and junior faculty. In addition, the Core has provided training in neuroAIDS research methodology to 188 junior researchers, including 39 who completed the HNRC mentored investigator program. We will continue these programs in the new grant cycle, with several improvements to increase their effectiveness. In addition, we plan to submit in January 2011 an application to the NIH for a T-32 Training Program for a broad range of neuroAIDS researchers (including pre- and post- doctoral trainees, in both clinical and non-clinical fields). This grant will expand on the HNRC's long history of training neurobehavioral and neuromedical scientists. Key accomplishments during the past funding period include the expansion of the Developmental Core goals to include mentoring and pilot study support for international trainees and collaborators, recruitment of young investigators interested in transdisciplinary research (molecular neuroimmunology, genetics, epidemiology, imaging), and receiving an R25 award to support an interdisciplinary clinician-researcher fellowship in neuroAIDS (IRFN). The IRFN provides training to clinicians interested in careers in neuroAIDS research. The training emphasizes the interdisciplinary and translational nature of clinical problems in neuroAIDS in order to prepare clinician scientists to tackle emerging questions in the field. A new goal for the Core is to utilize novel information technology webcasting to facilitate virtual mentoring and journal clubs. The virtual mentoring will be implemented in collaboration locally with the CFAR and UCSD clinical research curriculum (CREST) programs, and extramurally with the AIDS Research Centers at JHU and UNMC. With its multidisciplinary research environment, talented and productive research staff, highly organized and integrated infrastructure, and rich longitudinal specimen and data banks, the HNRC is well-positioned to develop and support expanded opportunities for innovative research by fostering preliminary studies and mentoring of trainees from a wide array of disciplines.

DESCRIPTION (provided by applicant): This R01 application builds upon a successful R21 grant that examined a cohort of Romanian adolescents and young adults who are long-term HIV survivors and who, despite over a decade of effective treatment, still demonstrate neuropsychological impairments (approx. 50% of subjects). The key feature of the next stage of this study is that these late teens and early 20s HIV+ cases, who were parenterally infected a long time ago, and for whom we have extensive longitudinal biological and treatment information, may experience altered maturation of the brain, with possible neurocognitive and social cognition sequelae. Prior to 1989, only 13 AIDS cases from Romania had been reported to the WHO, while by the end of 1990, 1168 cases were reported, of which 1094 were in children less than 13 years of age. Genetic characterization of the HIV circulating in these institutions revealed that all the children were infected with HIV clade F1 SA#1: Study the neuromedical (NM) characteristics of a long-term surviving cohort of HIV+ patients on HAART and compare them to the HAND features. We will examine the relationship between past and present NM data, including CD4 counts, VL, HAART and HAND-associated elements like: NP impairment, daily functioning, risk behavior, treatment adherence and psychiatric comorbidities. SA#2: Study the viral genetic factors associated with HAND in long-term survivors infected with clade F since early childhood. We will sequence and test in vitro the neurotropic potential of patient viral isolates and identify conserved viral genetic elements ('brain signature sequences') in the env (C2-V3) coding region, from HIV DNA extracted from the CSF and PBMC of subjects with or without HAND. Our study in the well-characterized Romanian cohort offers a unique opportunity to make prognostic correlations between host immune, viral, treatment, comorbid factors, and HAND in young adults who are living with HIV since childhood, most often being infected during the earliest stages of brain development. As these individuals mature, it will be important to understand the implications of neurocognitive impairment on their future behaviors.

This is a renewal application for the California NeuroAIDS Tissue Network (CNTN) in response to RFA-MH-18- 250. CNTN is an active participant in the National NeuroAIDS Tissue Consortium (NNTC), a partnership of four NIH-funded neuroAIDS tissue banks. The overarching objectives of the CNTN remains the same today as it was when it was first established in 1998 and encompass the 1) recruitment, clinical assessment, and follow- up of a late-stage HIV cohort, and 2) collection, maintenance, and distribution of specimens to investigators interested in conducting research on the neuropathogenesis of HIV-induced central and peripheral nervous system dysfunction. For the current application, and to address these objectives, CNTN will continue to maintain an in-life cohort of at least 150 participants (mostly people living with HIV/AIDS, PLWHA) with the purpose of obtaining autopsies from high priority cases that are aligned with the three thematic priorities in the RFA: a) HIV eradication from CNS reservoirs; b) mechanisms of HIV-associated neurocognitive disorders (HAND) in the setting of long-term HAART, and c) understanding comorbidities associated with HIV, including the effects of aging and chronic HIV-infection. CNTN will accumulate and manage a bank of in-life (plasma, CSF, blood, stool) and autopsy (brain, heart, lung, liver, kidney, lymph node, blood, and CSF) specimens and data from a cohort of persons living with HIV who are well characterized neuropsychologically, neuromedically, and psychiatrically. CNTN will additionally collect tissues (e.g., gut lymphoid tissue, testes) for emerging CNS cure and eradication research, and stool for microbiome research. Unique within the NNTC, the CNTN has assumed responsibility for CNS HIV-1 Antiretroviral Therapy Effects Research (CHARTER) specimens including plasma, CSF, buccal swabs, skin biopsies, and nucleic acids. De-identified CHARTER data sets (clinical, laboratory, genetic, neuroimaging, and research) have been transferred to the NNTC Data Coordinating Center (DCC), where they are now maintained. CNTN will maintain both the CNTN and CHARTER specimen resource abiding by strict quality assurance and quality control procedures, and will provide timely transfer of data and specimen inventories to the NNTC Data Coordinating Center (DCC). External requests for de-identified CNTN or CHARTER data or specimens are now managed by the DCC in collaboration with NNTC sites, and the CNTN team is well equipped to provide timely distribution of both CNTN and CHARTER specimens according to NNTC data and resource distribution policies. Finally, CNTN will continue to be an active collaborating member of the NNTC by: coordinating with the DCC and other NNTC sites; providing scientific and technical expertise to the wider research community as a voting member of the NNTC Steering Committee (SC), which reviews requests for data and specimens to facilitate neuroAIDS research; and as the leader of the NNTC Neuropsychology/Psychiatry subcommittee. Through the accomplishment of these objectives, the CNTN will continue to be a national and international resource serving the needs of neuroAIDS investigators.

The Neuroscience and Animal Models Core (NAM) Core serves both as a resource for TMARC and as a scientific platform for translating clinical observations into appropriate in vitro and in vivo experimental models to study mechanisms of disease associated with methamphetamine (METH)/HIV-induced brain injury. The Core Resource Objectives include: 1) Provide transgenic (gp120 and ITat) animals that exhibit central nervous system (CNS) pathology associated with HIV; 2) Provide the infrastructure for molecular analysis of the pathologic substrates in METH/HIV associated brain injury in HIV transgenic animals exposed to METH; furthermore, through linkage to the California NeuroAIDS Tissue Network (CNTN), the NAM Core will also access banked brain tissues that will support the translational aim of cross validating animal and human neuropathology, and finally, for in vitro studies we will provide experimental systems based on primary human neuroglial cultures, neuronal cell lines, and brain vascular smooth muscle cells; 3) Foster translational research ideas by supporting Pilot studies and training in the field of experimental neuropathology for young investigators. The Core Scientific Objectives include: 1) Analyze the neuropathology induced by METH exposure in HIV transgenic animals, young and aged; 2) Design neuropathologic analyses of HIV brains banked through the CNTN focused on aging, vascular and immune-mediated pathology associated with METH; 3) Through support of Pilot studies, the NAM Core will generate preliminary data for future developmental projects within TMARC focused on issues such as chronic brain inflammation, metabolic and oxidative stress, aging and brain vascular pathology, METH effects on social cognition in HIV transgenic animals, and neuroprotective interventions.

? DESCRIPTION (provided by applicant): In the current era of combination antiretroviral therapy (cART), HIV-associated neurocognitive disorders (HAND), mostly in milder forms, continue to affect the clinical outcome of HIV infection, even in the setting of systemic viral suppression. This revised proposal builds on our recent studies showing increased cerebral beta-amyloid (Aß) accumulation in the brains of HIV infected persons. We have also shown that cerebral Aß deposition was predictive of HAND among APOE e4 carriers, after adjusting for each co-morbid factor. Accordingly, the detection of APOE e4 and cerebral Aß deposition, i.e. decreases in cerebro-spinal fluid (CSF) Aß42 levels, may be useful in identifying HAND subjects who may benefit from Aß-targeted therapies. Based on our finding that isocortical p-Tau-immunoreactive neurofibrillary pathology was sparse in HIV subjects, CSF p-Tau measurement may be useful in differentiating HAND from Alzheimer's disease (AD) and other tauopathic disorders in older patients. It is also known that HIV infection and antiretroviral (ARV) treatment, particularly with protease inhibitors (ARV-PI) increase the risk of ischemic stroke, including cerebral small vessel disease (CSVD). Our overarching hypothesis is that cerebral Aß plaque deposition in HIV-infected patients is associated with defective phagocytotic function of microglia and perivascular clearance. We propose a novel concept that CSVD in the context of HIV/ARV-PI co-morbidity is mediated by oxidative stress- induced premature vascular aging and may be one of the key underpinnings of brain amyloid accumulation (via deficient clearance), and HAND. To test our working hypotheses we have formulated 3 specific aims that will navigate from clinico-pathologic and translational validation to mechanistic interventions. SA#1: Study the association between cerebral Aß plaques, ApoE4 genotype and HAND. We will use qualitative and semi- quantitative IHC to assess cerebral (perineuronal and perivascular) Aß plaques and compare them to apolipoprotein E (ApoE), and CSF measurements of Aß isoforms (-38, -40 and -42), in subjects with or without HAND. We will study the cerebral amyloid burden in 200 HIV+ autopsy cases with information on ART regimens and detailed neuromedical history. SA#2: Examine the association between HIV/ARV-PI co-morbidity and premature vascular aging in the human brain, amyloid accumulation, and HAND. We propose that the HIV/ARV-PI co-morbidity is associated with increased prelamin-A accumulation in vascular smooth muscle cells (VSMC) and premature brain vascular aging. SA#3: Investigate in vitro the effects of ARV-PI on macrophage amyloid phagocytosis and VSMC aging. We propose that exposure of VSMC to HIV and ARV-PI induce oxidative stress, leading to reduction in the Zmpste24 level, increased prelamin-A accumulation, and cellular aging; these pathologic processes may be interrupted by treatments with specific rescue drugs. Our proposal will validate the diagnostic value of amyloid monitoring in clinical specimens in individuals with increased genetic risk and identify potential therapeutic targets implicated in amyloid clearance.

NEUROBIOLOGY CORE PROJECT SUMMARY/ABSTRACT: The overall objective of the Neurobiology Core (NB) is to provide the NeuroAIDS community with a set of neurobiological resources that will enhance the analysis and discovery of the mechanisms of neurodegeneration associated with prolonged survival with HIV infection, from a comprehensive and dynamic perspective. The NB Core has been re-organized into In Vivo and In Vitro Units to better serve the current and future needs of the neuroAIDS field. The main resource objectives will be to: (a) provide a set of innovative state-of-the-art neuropathological and neurobiological in vivo and in vitro resources to support studies of the mechanisms of viral persistence/eradication, influence of microbiome in neuro-inflammation and role of aging in neurodegeneration with HIV infection, (b) encourage and facilitate collaborative work addressing these and other scientific themes of the Center, and (c) provide user training and consultation to new investigators. In addition, the NB Core Scientific objectives will include: (1) To provide support for studies of HIV infection in the CNS that address viral persistence and eradication, including molecular studies of chromatin modifiers, epigenetic markers and markers of viral production and cycling; (2) To provide in vitro and in vivo neuropathological resources and assays in support of the Microbiome theme, that could include studies of patterns of neuro-inflammation, neuro-vascular unit injury and gut pathology in patients with HAND; (3) To provide quantitative analysis of novel sets of HIV related neuropathologies in support of the theme on Aging. Examples of work on the Aging theme could include neuropathological and biochemical studies of: amyloid-? protein (A?) deposits including cerebral amyloid angiopathy; Tau and ?-synuclein accumulation; markers of autophagy and lysosomal activation; markers of mitochondrial biogenesis and mitophagy; brain immunophilin response; and human primary neuro-glial, brain endothelial and vascular smooth muscle cell cultures. And finally, (4) we will continue supporting clinico-pathological studies which investigate the relationship between new markers of neurodegeneration and HAND. Understanding the neuropathological basis for viral persistence and neural injury in the context of aging and the microbiome as contributing factors, will elucidate mechanisms through which HIV leads to HAND and inform new treatments for this disabling condition.