HIV-specific Immunity Derived From Chimeric Antigen Receptor-engineered Stem Cells

Abstract

The human immunodeficiency virus (HIV)-specific cytotoxic T lymphocyte (CTL) response is critical in controlling HIV infection. Since the immune response does not eliminate HIV, it would be beneficial to develop ways to enhance the HIV-specific CTL response to allow long-term viral suppression or clearance. Here, we report the use of a protective chimeric antigen receptor (CAR) in a hematopoietic stem/progenitor cell (HSPC)-based approach to engineer HIV immunity. We determined that CAR-modified HSPCs differentiate into functional T cells as well as natural killer (NK) cells in vivo in humanized mice and these cells are resistant to HIV infection and suppress HIV replication. These results strongly suggest that stem cell-based gene therapy with a CAR may be feasible and effective in treating chronic HIV infection and other morbidities.

Engineering HIV-Resistant, Anti-HIV Chimeric Antigen Receptor T Cells

“…31,56,57 However, CD4 + CAR T cells are expected to be vulnerable to HIV-1 infection, and there is evidence that CD8 + CAR T cells expressing the CD4-based CAR can be infected. 10,33 Because CCR5 is the predominant co-receptor used for HIV entry, we tested the effect of CCR5 disruption on HIVCAR T cell function. We have previously published the targeted integration of a CAR construct at the CCR5 locus with rates of 10%-15% in primary human T cells.…”

“…[7][8][9][10][11] Because residual HIV expression continues despite effective ART [12][13][14][15][16] and is required for viral rebound, HIV-infected cells should theoretically be targetable by a T cell therapeutic agent. Several mechanisms are thought to be responsible for the apparent failure of autologous cytotoxic T lymphocytes (CTLs) to clear reactivated cells in HIV-infected individuals: HIV evolution prior to ART quickly selects for CTL escape mutations; [17][18][19] HIV Nef mediates downregulation of major histocompatibility complex class I (MHC-I), 20,21 protecting HIV-infected cells from T cell receptor (TCR)-dependent CTL killing; and HIV-specific CTL responses may be limited by exhaustion 22,23 or peripheral immune tolerance.…”

“…[30][31][32] The efficacy of this approach was likely compromised because of limited CAR activity in the absence of an intracellular co-stimulatory signaling domain and the potential for HIV infection of T cells expressing the CD4 CAR. 10,33 A panel of novel high-affinity, broadly neutralizing monoclonal antibodies (bNAbs) recognizing the HIV envelope glycoprotein have been isolated and characterized over the last decade. 34,35 We predicted that single-chain variable fragments (scFvs) derived from these bNabs could be used to develop potent anti-HIV CARs (HIVCARs), and multiple scFvs could be selected to develop HIVCARs targeting different epitopes of the HIV envelope glycoprotein.…”

Engineering HIV-Specific Immunity with Chimeric Antigen Receptors

“…[30][31][32] The use of this CD4fCAR has important advantages, in that it has been found to be a safe reagent in multiple long-term clinical trials with over 500 patient years of clinical safety data 33,34 and this is strong evidence that it does not induce cytokine storms that have been an unwanted element with other CAR-based approaches in treating malignancies. 35,36 It is also unlikely to generate escape variants of HIV envelope as the loss of CD4 binding of an escape variant will likely have a dramatic effect on viral fitness.…”

“…We and others have done extensive testing of the antiviral function of CD8 + T cells transduced with CD4f CAR, finding that transduced cells are capable of killing HIV-infected cells and suppressing viral replication [30][31][32]34,37 and (unlike the HIV-specific TCR) that this activity is independent of HLA-I molecules. 38 CARs can also function in CD4 + T cells to act as HIV-1-specific helper cells.…”