Despite the success of antiretroviral therapy (ART) in decreasing mortality for HIV-infected individuals, ART has not cured HIV/AIDS. The failure to eradicate HIV infection during ART stems from the virus’ ability to persist in the body in multiple cell types and tissues. Without lifetime therapy, the virus quickly rebounds resulting in accelerated morbidity and mortality. The most commonly studied form of persistence is in memory CD4+ T-cells (CD4+ Tm-cells) that are harbouring the virus out of view of drugs or from the immune system. However, evidence indicates that other long-lived cells, known as myeloid cells, might contribute to HIV persistence. Cells that allow virus persistence are called viral reservoirs (VRs) and represent the main barrier to an HIV cure. While much is known about HIV persistence, many puzzles remain about the source of persistent HIV, the mechanisms underlying the establishment and persistence of VRs, particularly in CD4+ Tm-cells, and the ways to eliminate VRs. The Canadian HIV Cure Enterprise 2.0 (CanCURE 2.0), a team of leading Canadian HIV researchers, are pursuing an integrated and innovative research program informed by new knowledge in the field and new findings generated under CanCURE 1.0 (2014-2019). This collaborative project combines the efforts of prominent Canadian investigators, as well as two knowledge users who present the perspective of individuals living with HIV. The scientific program is based on three complementary research Themes.
●Theme 1 is aimed to uncover mechanisms by which specific antigens and antigen presenting cells of myeloid lineage lead to the establishment and persistence of VR in CD4+ Tm-cells.
●Theme 2 is aimed to define the direct contribution of long-lived self-renewing tissue-resident myeloid cells to HIV/SIV persistence during ART.
●Theme 3 is aimed to further develop innovative CanCURE 1.0 therapeutic interventions that target the VR in both T-cells and myeloid cells, notably macrophages, and translate new discoveries into therapeutic strategies.
Furthermore, CanCURE 2.0 research Cores support the Team with relevant animal models (Animal Models Core), and clinical platforms (Clinical Core). Interactions between research Theme units and Cores create a multidisciplinary approach driving the science towards our aim of generating effective therapeutic interventions against HIV persistence in individuals under antiretroviral therapy.
Theme 3 is aimed to further develop innovative CanCURE 1.0 therapeutic interventions that target the VR in both T-cells and MØ and translate new discoveries into therapeutic strategies.
The Animal Models Core develops animal models to test therapeutic approaches against persistent HIV viral reservoirs (VR) during antiretroviral therapy (ART). The Team benefits from models in simian immunodeficiency virus (SIV)-infected primates and humanized mice.
Co-Leaders: N. Chomont & T. Murooka
Participants: P. Ancuta, M.J. Tremblay, M. Ostrowski, A. Kumar, E.A. Cohen, K. Fowke, L. Falcone
Collaborator: M. A. Klein
Although the direct contribution of long-lived myeloid cells to HIV persistence during ART remains a subject of open investigation (to be explored in Theme 2), it is well established that HIV primarily persists in antigen-experienced memory CD4+T-cells. In individuals on ART, clonally expanded CD4+T-cells represent at least 50-60% of persistently infected cells harboring replication competent HIV. This suggests that proliferation of these cells, which is driven by the presence of antigens, critically contributes to the maintenance of the viral reservoir (cells that allow virus persistence). The generation and maintenance of memory T-cells require continual cell-to-cell interactions between antigen presenting cells and CD4+T-cells within lymphoid organs. Antigen presenting cells such as dendritic cells and macrophages present antigens in the context of class II major histocompatibility complex molecules, and together with soluble/membrane-bound co-stimulation signals, instruct and support long-term survival of antigen-specific CD4+T-cells. In humans, the establishment of long-term immunological memory, either through natural infection or vaccination, is restricted to unique antigens. Therefore, it is reasonable to assume that HIV reservoirs are also established and maintained in CD4+T-cells with unique antigen specificities. In Theme 1, CanCURE investigators will investigate whether specific antigens have the ability to imprint CD4+T-cells with unique metabolic/transcriptional profiles that can be exploited by the HIV virus to promote viral reservoir establishment and persistence.
Co-Leaders: P. Ancuta & J. Estaquier
Participants: C. Power, A. Jenabian, C. Costiniuk, E. A. Cohen, E. Haddad, M. J. Tremblay, N. Chomont, J-P. Routy, J. Angel, M. Ostrowski; M. A. Jenabian, R. Rosenes; S. Margolese.
Collaborators: J. Estes, F. Ginhoux, R. Bendayan, T. Mesplède, F. Villinger
HIV persistence in macrophages depends on their permissiveness to HIV infection, as well as their long-term survival capacity. A paradigm shift occurred very recently concerning the ontogeny (the origination and development) of tissue-resident macrophages. For many years it was known that macrophages from brain (microglia), liver (Kuppfer cells) and lungs (alveolar macrophages) are derived from local embryonic/fetal precursors and represent long-lived self-renewing tissue-resident macrophages. In contrast, it was considered that macrophages present in all the other tissues are derived from blood monocytes originating from bone-marrow precursors after birth, and represent short-lived macrophages, with accelerated turnover especially in the intestine. However, recent evidence documented the presence of long-lived self-renewing tissue-resident macrophages in multiple deep tissues, including the arteries and heart, and very recently the intestine. Long-lived self-renewing tissue-resident macrophages originate from local stem cell precursors of the yolk-sac or the fetal liver during embryogenesis, as well as from monocytes immediately after birth, and exhibit self-renewal capacity independently of bone-marrow precursors after birth.This progress led to a novel myeloid cell nomenclature first based on ontogeny and then on tissue localization. After birth, long-lived self-renewing tissue-resident macrophages coexist with short-lived macrophages (mainly generated during inflammatory processes) in deep tissues, with the proportion between these two pools varying from homeostasis to tissue damage and during aging. In Theme 2, CanCURE investigators will document the presence of long-lived self-renewing tissue-resident macrophages versus short-lived macrophages in deep tissues from humans, humanized-mice and non-human primates and explore their contribution to viral reservoir persistence and tissue homeostasis/inflammation during ART.
Leaders: J. Angel & J-P. Routy
Participants: M. Ostrowski, A. Kumar, E.A. Cohen, E. Haddad, B. Cameron, J. Estaquier, P. Ancuta, N. Chomont, L. Falcone, C Costiniuk, R. Rosenes, S. Margolese.
Collaborators: M-A. Langlois, R. Korneluk, E. Lacasse, R. Bendayan
In Theme 3, CanCURE investigators will continue to develop therapeutic strategies emanating from CanCURE 1.0, and from discoveries expected from Themes 1 and 2, targeting viral reservoirs in both T cells and myeloid cells, with the goal of developing more effective strategies for HIV cure.
To continue on with the pre-clinical work progressing from CanCURE 1.0. Drs Angel and Cohen will work together on targeting the HIV reservoir with rhabdovirus-based oncolytic viruses that selectively infects and kills cells that harbour HIV proviral DNA.
Drs Ostrowski and Costiniuk will work together on assessing the impact of the HIV-1 Nef blockade on the elimination of productively and latently infected human macrophages by autologous HIV-specific T-cells. Drs Kumar and Cohen will work with the involvement of Smac mimetics (SM), inhibitors of IAP proteins in the selective killing of HIV-infected human macrophages and latently infected CD4+ T-cells.
To continue on with clinical trials progressing from CanCURE 1.0 as well as developing from Themes 1 & 2. In Aim 3.2, Drs Ancuta, Routy, Angel, Chomont and Falcone will study the effect of metformin on HIV reservoir size and dysbiosis in non-diabetic ART-treated patients: The lilac study (CTNPT 027). Drs Cameron, Angel, Ancuta and Chomont will study the effect of Vedolizumab during ART and ATI: Rebound Viremia Kinetics in the dose- ranging HAVARTI trial (CTNPT 031). Drs Angel, Cameron, and Estaquier will work together on a Phase I study of a pan Caspase inhibitor, Q-VD, in ART-treated HIV-infected adults. Drs Routy, Ancuta, Chomont and Falcone will work together on the Camu Camu prebiotic effects on circulating Lipopolysaccharide, immune activation and HIV reservoir size in ART-treated participants (CTNPT 032).
The Animal Core develops animal models to test therapeutic approaches against persistent HIV viral reservoirs (VR) during antiretroviral therapy (ART). The Team benefits from models of simian immunodeficiency virus (SIV)-infected non-human primates as well as humanized mice infected with HIV.
The Primates Core is localized at Université Laval. The Core facility will continue providing the expertise and tools for analyzing immune and viral dynamics in Rhesus macaques as well as molecular and virological assays for the detection of SIV reservoirs. The purpose of this core is to provide high consistency and quality animal care and housing, execution of study protocols and experimental procedures, specimen collection and processing, performance of necropsies and acquisition of clinical and pathological data necessary to meet the CanCURE program objectives.
The Humanized Mice Core is localized at the CHU Sainte-Justine Research Centre in Montreal and develops "NOD scid gamma (NSG)" and “bone marrow, liver, thymus (BLT)” humanized mice models for projects involving in vivo HIV infections.
Co-Leaders: J. Angel & J-P. Routy
This core closely coordinates its efforts with the CIHR Canadian HIV Trials Network (CTN), which facilitates the development, execution and dissemination of HIV cure clinical trials in Canada. The clinical core plays a central role in providing cells/tissues from leukapheresis, colon biopsies, lymph node biopsies, BAL as well as access to testicular tissues. The recent establishment of protocols at OHRI, University of Toronto, and McGill University Health Center (leader of the McGill Autopsy Biobank Initiative Dr. Cecilia Costiniuk) for research on tissues/cells obtained at autopsy of consenting ART-treated HIV+ individuals greatly extends the variety of tissues that the clinical core provides to support CanCURE 2.0 studies.