Histone Deacetylase Inhibitors Impair the Elimination of HIV-Infected Cells by Cytotoxic T-Lymphocytes

ABSTRACT Recently it was shown that influenza A viruses can accumulate mutations in epitopes associated with escape from recognition by human virus-specific cytotoxic T lymphocytes (CTL). It is unclear what drives diversification of CTL epitopes and why certain epitopes are variable and others remain conserved. It has been shown that simian immunodeficiency virus-specific CTL that recognize their epitope with high functional avidity eliminate virus-infected cells efficiently and drive diversification of CTL epitopes. T-cell functional avidity is defined by the density of major histocompatibility complex class I peptide complexes required to activate specific CTL. We hypothesized that functional avidity of CTL contributes to epitope diversification and escape from CTL also for influenza viruses. To test this hypothesis, the functional avidity of polyclonal CTL populations specific for nine individual epitopes was determined. To this end, peripheral blood mononuclear cells from HLA-A- and -B-genotyped individuals were stimulated in vitro with influenza virus-infected cells to allow expansion of virus-specific CTL, which were used to determine the functional avidity of CTL specific for nine individual epitopes in enzyme-linked immunospot assays. We found that the functional avidity for the respective epitopes varied widely. Furthermore, the functional avidity of CTL specific for the hypervariable NP418-426 epitope was significantly higher than that of CTL recognizing other epitopes (P < 0.01). It was speculated that the high functional avidity of NP418-426-specific CTL was responsible for the diversification of this influenza A virus CTL epitope.

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Naturally processed viral peptides recognized by cytotoxic T lymphocytes on cells chronically infected by human immunodeficiency virus type 1.

Journal of Experimental Medicine ◽

10.1084/jem.180.4.1283 ◽

1994 ◽

Vol 180 (4) ◽

pp. 1283-1293 ◽

Cited By ~ 162

Author(s):

T J Tsomides ◽

A Aldovini ◽

R P Johnson ◽

B D Walker ◽

R A Young ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

T Lymphocytes ◽

Cell Lines ◽

Cytotoxic T Lymphocytes ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Immunodeficiency Virus ◽

Infected Cells ◽

Hiv 1

We have established long-term cultures of several cell lines stably and uniformly expressing human immunodeficiency virus type 1 (HIV-1) in order to (a) identify naturally processed HIV-1 peptides recognized by cytotoxic T lymphocytes (CTL) from HIV-1-seropositive individuals and (b) consider the hypothesis that naturally occurring epitope densities on HIV-infected cells may limit their lysis by CTL. Each of two A2-restricted CD8+ CTL specific for HIV-1 gag or reverse transcriptase (RT) recognized a single naturally processed HIV-1 peptide in trifluoroacetic acid (TFA) extracts of infected cells: gag 77-85 (SLYNTVATL) or RT 476-484 (ILKEPVHGV). Both processed peptides match the synthetic peptides that are optimally active in cytotoxicity assays and have the consensus motif described for A2-associated peptides. Their abundances were approximately 400 and approximately 12 molecules per infected Jurkat-A2 cell, respectively. Other synthetic HIV-1 peptides active at subnanomolar concentrations were not present in infected cells. Except for the antigen processing mutant line T2, HIV-infected HLA-A2+ cell lines were specifically lysed by both A2-restricted CTL, although infected Jurkat-A2 cells were lysed more poorly by RT-specific CTL than by gag-specific CTL, suggesting that low cell surface density of a natural peptide may limit the effectiveness of some HIV-specific CTL despite their vigorous activity against synthetic peptide-treated target cells.

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Activation of Latent HIV-1 T Cell Reservoirs with a Combination of Innate Immune and Epigenetic Regulators

Journal of Virology ◽

10.1128/jvi.01194-19 ◽

2019 ◽

Vol 93 (21) ◽

Cited By ~ 2

Author(s):

Enrico Palermo ◽

Chiara Acchioni ◽

Daniele Di Carlo ◽

Alessandra Zevini ◽

Michela Muscolini ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Lymphocytes ◽

Histone Deacetylase ◽

Innate Immune ◽

Viral Reservoir ◽

Hiv Eradication ◽

Shock And Kill ◽

Infected Cells ◽

Hiv 1

ABSTRACT The presence of T cell reservoirs in which human immunodeficiency virus (HIV) establishes latency by integrating into the host genome represents a major obstacle to an HIV cure and has prompted the development of strategies aimed at the eradication of HIV from latently infected cells. The “shock-and-kill” strategy is one of the most pursued approaches to the elimination of viral reservoirs. Although several latency-reversing agents (LRAs) have shown promising reactivation activity, they have failed to eliminate the cellular reservoir. In this study, we evaluated a novel immune system-mediated approach to clearing the HIV reservoir, based on a combination of innate immune stimulation and epigenetic reprogramming. The combination of the STING agonist cGAMP (cyclic GMP-AMP) and the FDA-approved histone deacetylase inhibitor resminostat resulted in a significant increase in HIV proviral reactivation and specific apoptosis in HIV-infected cells in vitro. Reductions in the proportion of HIV-harboring cells and the total amount of HIV DNA were also observed in CD4+ central memory T (TCM) cells, a primary cell model of latency, where resminostat alone or together with cGAMP induced high levels of selective cell death. Finally, high levels of cell-associated HIV RNA were detected ex vivo in peripheral blood mononuclear cells (PBMCs) and CD4+ T cells from individuals on suppressive antiretroviral therapy (ART). Although synergism was not detected in PBMCs with the combination, viral RNA expression was significantly increased in CD4+ T cells. Collectively, these results represent a promising step toward HIV eradication by demonstrating the potential of innate immune activation and epigenetic modulation for reducing the viral reservoir and inducing specific death of HIV-infected cells. IMPORTANCE One of the challenges associated with HIV-1 infection is that despite antiretroviral therapies that reduce HIV-1 loads to undetectable levels, proviral DNA remains dormant in a subpopulation of T lymphocytes. Numerous strategies to clear residual virus by reactivating latent virus and eliminating the reservoir of HIV-1 (so-called “shock-and-kill” strategies) have been proposed. In the present study, we use a combination of small molecules that activate the cGAS-STING antiviral innate immune response (the di-cyclic nucleotide cGAMP) and epigenetic modulators (histone deacetylase inhibitors) that induce reactivation and HIV-infected T cell killing in cell lines, primary T lymphocytes, and patient samples. These studies represent a novel strategy for HIV eradication by reducing the viral reservoir and inducing specific death of HIV-infected cells.

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RMA/S cells present endogenously synthesized cytosolic proteins to class I-restricted cytotoxic T lymphocytes.

Journal of Experimental Medicine ◽

10.1084/jem.175.1.163 ◽

1992 ◽

Vol 175 (1) ◽

pp. 163-168 ◽

Cited By ~ 88

Author(s):

F Esquivel ◽

J Yewdell ◽

J Bennink

Keyword(s):

T Lymphocytes ◽

Cell Surface ◽

Cytotoxic T Lymphocytes ◽

Antigen Processing ◽

Mutant Cell ◽

Surface Expression ◽

Class I ◽

Cell Surface Expression ◽

Antigenic Peptides ◽

Infected Cells

RMA/S is a mutant cell line with decreased cell surface expression of major histocompatibility complex class I molecules that has been reported to be deficient in presenting endogenously synthesized influenza virus nucleoprotein (NP) to cytotoxic T lymphocytes (CTL). In the present study we show that RMA/S cells can present vesicular stomatitis virus nucleocapsid protein, and, under some conditions, NP, to Kb-and Db-restricted CTL, respectively. Antigen presentation results from processing of cytosolic pools of endogenously synthesized proteins, and not the binding to cell surface class I molecules of antigenic peptides present in the virus inoculum or released from infected cells. Antigen processing of RMA/S differs, however, from processing by wild-type cells in requiring greater amounts of antigen, longer times to assemble or transport class I-peptide complexes, and in being more sensitive to blocking by anti-CD8 antibody. Thus, the antigen processing deficit in RMA/S cells is of a partial rather than absolute nature.

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The advantage of early recognition of HIV-infected cells by cytotoxic T-lymphocytes

Vaccine ◽

10.1016/s0264-410x(02)00089-0 ◽

2002 ◽

Vol 20 (15) ◽

pp. 2011-2015 ◽

Cited By ~ 40

Author(s):

Rob A Gruters ◽

Carel A van Baalen ◽

Albert D.M.E Osterhaus

Keyword(s):

T Lymphocytes ◽

Cytotoxic T Lymphocytes ◽

Early Recognition ◽

Infected Cells

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HLA B37 determines an influenza A virus nucleoprotein epitope recognized by cytotoxic T lymphocytes.

Journal of Experimental Medicine ◽

10.1084/jem.164.5.1397 ◽

1986 ◽

Vol 164 (5) ◽

pp. 1397-1406 ◽

Cited By ~ 59

Author(s):

A J McMichael ◽

F M Gotch ◽

J Rothbard

Keyword(s):

Amino Acids ◽

T Cells ◽

T Lymphocytes ◽

Influenza A Virus ◽

Cytotoxic T Lymphocytes ◽

Synthetic Peptide ◽

Influenza A ◽

Cytotoxic T Cells ◽

Human Influenza ◽

Infected Cells

Human influenza A virus-specific, cytotoxic T cells have been shown previously to recognize the virus nucleoprotein on infected cells. CTL preparations from four HLA B37-positive donors were shown to recognize a synthetic peptide that corresponded to amino acids 335-349 of the nucleoprotein sequence. Influenza-specific CTL from 10 donors of other HLA types failed to recognize this epitope. CD8+ CTL lines were derived from lymphocytes of two HLA B37-positive donors and used to show that the peptide was represented on virus-infected cells and to determine the probable boundaries of the epitope.

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