Tracy Fischer-Smith, Ph.D. - US grants

AIDS; ATGN; Acquired Immune Deficiency; Acquired Immune Deficiency Syndrome; Acquired Immuno-Deficiency Syndrome; Acquired Immunodeficiency Syndrome; Affect; Animals; Antigens; Autopsy; Body Tissues; Classification; Detection; Evaluation; Fluorescence Microscopy; Genetics, in situ Hybridization; Histopathology; Immunologic Deficiency Syndrome, Acquired; In Situ Hybridization; Macaca mulatta; Messenger RNA; Methods and Techniques; Methods, Other; Microscopy, Fluorescence; Microscopy, Light, Fluorescence; Pathogenesis; Pathologic; Procedures; Process; Purpose; RNA, Messenger; Research Specimen; Rhesus; Rhesus Macaque; Rhesus Monkey; SIV; Simian Immunodeficiency Viruses; Specimen; Standards; Standards of Weights and Measures; Systematics; Techniques; Tissue Sample; Tissues; Visceral; abused drugs; drug of abuse; drugs abused; drugs of abuse; experiment; experimental research; experimental study; immunogen; in situ Hybridization Staining Method; light microscopy; mRNA; necropsy; postmortem; research study

[unreadable] DESCRIPTION (provided by applicant): The advent of highly active anti-retroviral therapy (HAART) has reduced the incidence of HIV-1 associated dementia (HIV-D); however, the prevalence has risen, as HIV-1-infected individuals are now living longer with AIDS. The initiation of HAART therapy in patients exhibiting neurocognitive abnormalities has often demonstrated dramatic benefits, despite poor penetrance of anti-retroviral drugs across the blood brain barrier (BBB). Our major hypothesis put forth in this application is that alterations in monocyte/macrophage (MF) homeostasis, which leads to the expansion of a more invasive monocyte subset that is able to enter the CNS compartment in HIV-D, is responsive to HAART. CD163, a hemoglobin/haptoglobin scavenger receptor, has been reported by several groups as an identifying marker of the immunosuppressive macrophage type 2 (MF- 2). We observed significant accumulation of CD163+/CD16+ MFs in the CNS of patients with HIV encephalopathy (HIVE), the neuropathology of HIV-D, located perivascularly, within nodular lesions and in the brain parenchyma. These cells are the major reservoir of productive HIV-1 infection in the CNS. In a separate study, we found an increase in the percent frequency of circulating CD163+/CD16+ monocytes in HIV-1 infected individuals with detectable viral loads when compared with HIV-1 infected persons under successful pharmacological intervention and seronegative individuals. Moreover, expansion of this monocyte subset correlates strongly with viral load and CD4+ T cell loss This subset, which is CD163+/CD16+, may be more permissive to HIV-1 infection and contribute to the development of cognitive dysfunction by bringing virus into the CNS as well as through secreted factors and by-products associated with their activation status. We further hypothesize that the reduction in the incidence of HIV-D in the HAART era is, at least in part, reflective of the ability of HAART to restore monocyte/ MF homeostasis. The studies proposed in this application have three Specific Aims. Specific Aim 1 will test the hypothesis that monocyte/MF homeostasis is dysregulated in HIV-1 infected individuals, which is attenuated or reversed by successful HAART therapy. Specific Aim 2 Specific will test the hypothesis that the CD163+/CD16+ perivascular and parenchymal MFs that accumulate in the CNS in HIV-1 infected individuals with encephalopathy exhibit immune polarization, consistent with altered monocyte/MF homeostasis. Finally, Specific Aim 3 will test the hypothesis that monocyte subset homeostasis is altered by HIV-1 infection in vivo and in vitro. The studies proposed in this application should provide novel insights regarding the role of altered monocyte/ MF homeostasis in HIV induced neurocognitive disorders. [unreadable] [unreadable] [unreadable]

RESEARCH SUMMARY Combination antiretroviral therapy (cART) has significantly increased the longevity and quality of life for people living with HIV, however, it does not target long-lived virus-infected cells, such as tissue macrophages (M¿)s, leaving persistent reservoirs of virus unaffected. In addition to presenting a major obstacle in virus eradication, this limitation of cART allows for the continued development and progression of HIV-related pathologies, including HIV-associated neurocognitive dysfunction (HAND). Previous work from our laboratory suggest that in HIV infection, monocyte/M¿ homeostasis is skewed to an immunosuppressive type 2 phenotype, which supports viral persistence in M¿s and invasion of infected and non-infected M¿s in the brain. In the studies proposed in this application, we will explore our hypothesis that that monocyte/M¿ homeostasis is dysregulated through chronic and/or augmented cFMS signaling in HIV infection that facilitates the establishment, expansion and maintenance of M¿ viral reservoirs, as well as immune suppression. Through in vitro studies, we will evaluate the effect of ligands for cFMS, M-CSF and IL-34, on primary monocyte/M¿ maturation and polarization, survival and migration, within and outside the context of HIV infection, as well as investigate differences and similarities in M-CSF and IL-34 cFMS signaling pathways. Expression of M-CSF, IL-34, cFMS, and other markers and factors associated with M¿ activation/polarization will be investigated in banked plasma and (non-matched) postmortem brain tissue from patients with and without HIV-1 infection. We also hypothesize that targeting cFMS can be used to correct monocyte/M¿ immune polarization and restore appropriate immune responses that will enable the immune system to clear cellular HIV reservoirs. To explore this hypothesis, we will evaluate the ability of compounds that inhibit cFMS kinase to restore monocyte/M¿ immune homeostasis and function and promote the elimination of reservoirs of HIV infected M¿s by reducing virus replication in M¿s, as well as support appropriate adaptive immune responses. Candidate compounds will include those that can be advanced for investigation in the SIV rhesus macaque animal model of HIV infection. We anticipate these studies will reveal important insights into how viral persistence is achieved in tissue M¿s and present a novel strategy for targeted therapeutic design to eradicate HIV-1 infection through the restoration of immune function, leading to the effective elimination of long-lived viral reservoirs.

CORE B SUMMARY The overall objective of this program project application is to examine the consequence of monocyte/MF immune modulation on the development and maintenance of MF HIV reservoirs and HIV disease progression, using SIVmac251 infected Indian rhesus macaques. Core B: Immunopathology Core will evaluate the effectiveness of each project's therapeutic strategy for reducing inflammation and the reservoir of SIV in brain and lymphoid organs. Antigens of interest, as they relate to each of the projects, will be examined in necropsy tissues of experimental animals. This will provide a standardized means for evaluating tissues and centralizing the investigations and findings, allowing for greater collaboration between projects, as well as providing for the best use of the specimens. Furthermore, we will evaluate tissues for the presence of productive and provirus in tissues to evaluate the effectiveness of the therapeutic strategies in resolving tissue MFs of SIV infection. We anticipate that these studies will advance our understanding of the role of monocytes/MFs in the development and maintenance of reservoirs of persistent infection, as well as HIV-related disease progression, including HIV-associated neurocognitive dysfunction.