2006 — 2010 |
Eugenin, Eliseo A |
K01Activity Code Description: For support of a scientist, committed to research, in need of both advanced research training and additional experience. |
The Role of Gap Junction Channels in Neuroaids @ Albert Einstein College of Medicine
DESCRIPTION (provided by applicant): Gap junctions (GJ) are the only channels by which cells can communicate directly with the cytoplasm of neighboring cells. In the nervous system neuronal stem cells, neurons, astrocytes, oligodendrocytes, blood brain barrier cells (endothelial and astrocytes), and under inflammatory conditions, microglia express GJ. The normal function of these channels is to propagate intercellular messengers, such as calcium, nucleotides, IPS, metabolites, and electrical signals that ultimately coordinate tissue homeostasis, proliferation, differentiation, metabolism and cell death. To date little is known about the role that GJ play during the pathogenesis of human nervous system diseases, including HIV-infection. Almost all the data have been obtained in mouse and rat models. Our preliminary data, using human cells, are the first evidence that GJ may actively participate in NeuroAIDS. We propose that they amplify toxic signals generated by HIV-infected astrocytes. Our hypothesis is that HIV infected astrocytes use intercellular communication through gap junctions to spread toxic and inflammatory signals into uninfected cells to compromise their function and viability, leading further to CNS dysfunction. To address this hypothesis three Aims are proposed. Aim 1: To determine the mechanisms by which HIV- infection in astrocytes maintain or enhances or expression of GJ. Aim 2: To determine the pathophysiological consequences of gap junction communication between HIV-infected astrocytes and uninfected cells. Aim 3: To determine the signal (s) that diffuse through gap junctions to alter the function of uninfected cells. The results from these studies should contribute to our understanding of the role of gap junction channels in the development of NeuroAIDS, and may indicate new strategies to control the neurodegeneration often associated with HIV-infection. In addition, this proposal represents an outstanding opportunity for me to be trained in an outstanding environment, in the laboratory of Dr. Joan W. Berman, where studies of NeuroAIDS are ongoing, and at The Albert Einstein College of Medicine.
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1 |
2012 — 2020 |
Eugenin, Eliseo A |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Astrocyte Connexin43 Containing Channels Amplify Cns Dysfunction in Neuroaids @ University of Texas Med Br Galveston
Abstract: As of 2014, an estimated 35 million persons worldwide were living with human immunodeficiency virus (HIV). Early after primary infection, HIV enters the CNS and causes long lasting cognitive and motor impairment in 30-60 % of infected individuals, even in the current antiretroviral era. As infected individuals are living longer, the prevalence of neurological complications has been increasing. In the CNS, HIV infects mostly microglia/macrophages, but also a small population of astrocytes. However, despite the key roles of astrocytes in CNS functions, the role of these cells in NeuroAIDS has been relatively ignored. Our studies during the last funding period provide strong evidence for the critical role of astrocytes in the pathogenesis of NeuroAIDS. In particular, we have demonstrated that despite relatively low numbers of infected astrocytes and low to undetectable HIV replication, the HIV infected astrocytes transmit apoptotic and inflammatory signals, including calcium and inositol triphosphate (IP3), to neighboring uninfected cells, promoting neuronal damage and demise. We have also shown that these pro-apoptotic molecules are spread from the few HIV infected astrocytes via connexin-43 (Cx43) containing gap junctions (GJ) and unopposed hemichannels (uHC), whose expression and opening is regulated by HIV. Indeed, blocking GJ or uHC reduced amplification of bystander apoptosis, cellular dysfunction, synaptic compromise, and mitochondrial dysfunction induced by HIV infected astrocytes. Interestingly, HIV infected astrocytes themselves are protected from apoptosis by mechanisms that involve altered apoptosome formation and mitochondrial function. Importantly, we have tested and validated most of the mechanisms operating in HIV infected astrocytes in vivo in human and monkey brain tissue sections. Thus, based on the results obtained during the extremely productive period funded by our first R01 (resulting in over 40 publications in high quality peer reviewed journals) we have formulated our current hypothesis that ?HIV infected astrocytes survive HIV infection to become HIV reservoirs, and that these cells send toxic, pro-apoptotic signals to surrounding cells via Cx43 containing channels, leading to the CNS dysfunction and NeuroAIDS?. In this application we propose to characterize the novel pathways of HIV toxicity within the brain and to identify the role of GJ and uHC in CNS dysfunction. The results obtained from this proposal will lead to the identification of potential novel therapeutic targets to limit the devastating consequences of NeuroAIDS.
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0.922 |
2017 — 2021 |
Eugenin, Eliseo A |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Role of Pannexin-1 Hemichannels in Neuroaids @ Rbhs-New Jersey Medical School
Project Abstract: According to WHO and UN reports, in 2014 an estimated 34 million persons worldwide were living with HIV. In addition to compromising the immune system, HIV can also infect the CNS early during the disease, leading to devastating neurological consequences (NeuroAIDS). A growing body of evidence indicates that neurological damage in NeuroAIDS is triggered not by the active viral replication but by the transmigration of HIV-infected leukocytes into the brain and the associated neuroinflammation. While it is well established that HIV uses host-encoded proteins to facilitate viral infection, replication and transmigration into the CNS, specific host factors involved in the pathogenesis of NeuroAIDS are still extremely poorly understood. Our laboratory recently identified pannexin-1 channels as essential components of the HIV life cycle in immune cells as well as in the pathogenesis of NeuroAIDS. In particular, we and others have demonstrated that pannexin-1 channel opening facilitates multiple steps of HIV-mediated CNS compromise, including: (1) regulation of CCR5 surface aggregation and trafficking in response to HIV infection; (2) HIV entry by direct regulation of the channel opening and subsequent release of intracellular ATP, auto-activating purinergic receptors; (3) release of intracellular factors such as ATP that promote inflammation; (4) monocyte differentiation and maturation in response to chemokines and/or HIV; (5) increased expression of several adhesion molecules required for leukocytes to transmigrate across the BBB; (6) neuroinflammation. We also found that ATP compromises BBB integrity and function, and our analysis of a large number of patient samples suggests that circulating ATP may be a biomarker of CNS disease. Our preliminary data indicate that different ethnic groups carry specific pannexin-1 polymorphisms and have differential expression and opening of this channel, potentially underlying, at least in part, the observed variation in susceptibility to HIV infection and NeuroAIDS among different ethnicities. Our recent preliminary data indicate that circulating ATP concentrations and their correlation with CNS compromise are also ethnicity related. Importantly, pannexin-1 channels have excellent potential as a therapeutic target because (1) their opening can be effectively blocked in vivo using several pannexin-1 channel blockers, including a specific mimetic peptide we recently designed; and (2) these channels mostly exist in a closed state under physiological conditions, minimizing potential side effects. This proposal is designed to define the mechanisms linking pannexin-1 channel opening to HIV receptor expression, trafficking, and function (Aim 1), leukocyte differentiation and transmigration into the CNS (Aim 2), and the role of neuroinflammatory factors released through the channel in BBB and CNS function (Aim 3). Finally, in Aim 4 we will examine the role of pannexin-1 channels in two animal models. Together, these experiments will reveal the role of an important new host factor in NeuroAIDS.
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0.922 |
2021 |
Eugenin, Eliseo A |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Metabolic Strategies to Eliminate Cns Myeloid Viral Reservoirs @ University of Texas Med Br Galveston
Abstract: HIV cure has not been achieved due to long-lasting latent HIV reservoirs that, upon ART interruption, reactivate the virus. The best characterized viral reservoirs are different circulating subpopulations of T lymphocytes, but it has become evident that most viral reservoirs are localized in several tissues, including the brain. However, little is known about HIV persistence in myeloid cells, becoming a controversial issue. Only recently, genetic phylogenetic analysis indicates that viral reactivation cannot be explained by CD4 T containing the virus. Thus, alternative reservoirs need to be considered, such as a myeloid cell. Myeloid tissue-associated cells have multiple advantages over T cells to consider long-lasting viral reservoirs including tissue location, long-life, slow turn around, and higher resistance to apoptosis compared to T cells. In the brain, microglia and macrophages are the main cell type with HIV-integrated. Our data identify macrophage/microglia as a key viral reservoir within the brain, even in long-term ART. We developed an in vitro system to generate latent infected microglia or macrophages that can be reactivated by multiple treatments, including Meth, LPS, and LRA. The latently HIV-infected macrophages/microglia cells survive infection by blocking the apoptosome's formation by increasing bim protein expression, preventing further apoptosis. Further, we identified that latently HIV-infected cells (microglia/macrophages) had a unique metabolic signature that relies on glutamate/glutamine for ATP production and survival. More surprising is that HIV reservoirs cannot switch between different carbon sources such as lipids, glucose, or unusual sources of carbon like amino acids like uninfected cells. Blocking these metabolic pathways results in significant apoptosis of HIV reservoirs even in the absence of reactivation. Our results will provide a better understanding of the mechanisms that regulate the generation and survival of HIV myeloid reservoirs within the CNS and provide essential information for eradicating these viral reservoirs from the CNS.
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0.922 |