Productive infection and subsequent interaction of CD4-gp120 at the cellular membrane is required for HIV-induced apoptosis of CD4+ T cells

Abstract Background Macrophages, besides resting latently infected CD4+ T cells, constitute the predominant stable, major non-T cell HIV reservoirs. Therefore, it is essential to eliminate both latently infected CD4+ T cells and tissue macrophages to completely eradicate HIV in patients. Until now, most of the research focus is directed towards eliminating latently infected CD4+ T cells. However, few approaches have been directed at killing of HIV-infected macrophages either in vitro or in vivo. HIV infection dysregulates the expression of many host genes essential for the survival of infected cells. We postulated that exploiting this alteration may yield novel targets for the selective killing of infected macrophages. Methods We applied a pooled shRNA-based genome-wide approach by employing a lentivirus-based library of shRNAs to screen novel gene targets whose inhibition should selectively induce apoptosis in HIV-infected macrophages. Primary human MDMs were infected with HIV-eGFP and HIV-HSA viruses. Infected MDMs were transfected with siRNAs specific for the promising genes followed by analysis of apoptosis by flow cytometry using labelled Annexin-V in HIV-infected, HIV-exposed but uninfected bystander MDMs and uninfected MDMs. The results were analyzed using student’s t-test from at least four independent experiments. Results We validated 28 top hits in two independent HIV infection models. This culminated in the identification of four target genes, Cox7a2, Znf484, Cstf2t, and Cdk2, whose loss-of-function induced apoptosis preferentially in HIV-infected macrophages. Silencing these single genes killed significantly higher number of HIV-HSA-infected MDMs compared to the HIV-HSA-exposed, uninfected bystander macrophages, indicating the specificity in the killing of HIV-infected macrophages. The mechanism governing Cox7a2-mediated apoptosis of HIV-infected macrophages revealed that targeting respiratory chain complex II and IV genes also selectively induced apoptosis of HIV-infected macrophages possibly through enhanced ROS production. Conclusions We have identified above-mentioned novel genes and specifically the respiratory chain complex II and IV genes whose silencing may cause selective elimination of HIV-infected macrophages and eventually the HIV-macrophage reservoirs. The results highlight the potential of the identified genes as targets for eliminating HIV-infected macrophages in physiological environment as part of an HIV cure strategy.

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Macrophage-dependent Apoptosis of CD4+ T Lymphocytes from HIV-infected Individuals Is Mediated by FasL and Tumor Necrosis Factor

Journal of Experimental Medicine ◽

10.1084/jem.185.1.55 ◽

1997 ◽

Vol 185 (1) ◽

pp. 55-64 ◽

Cited By ~ 181

Author(s):

Andrew D. Badley ◽

David Dockrell ◽

Margaret Simpson ◽

Ron Schut ◽

David H. Lynch ◽

...

Keyword(s):

T Cells ◽

Tumor Necrosis Factor ◽

T Lymphocytes ◽

Cd4 T Cells ◽

Tumor Necrosis ◽

Human Macrophages ◽

Infected Cells ◽

Induced Apoptosis ◽

Antigen Presenting ◽

Necrosis Factor

Apoptosis of bystander uninfected CD4+ T lymphocytes by neighboring HIV-infected cells is observed in cell culture and in lymphoid tissue of HIV-infected individuals. This study addresses whether antigen-presenting cells such as human macrophages mediate apoptosis of CD4+ T cells from HIV-infected individuals. Uninfected human macrophages, and to a larger degree, HIV-infected macrophages mediate apoptosis of T cells from HIV-infected, but not from uninfected control individuals. This macrophage-dependent killing targets CD4+, but not CD8+ T lymphocytes from HIV-infected individuals, and direct contact between macrophages and lymphocytes is required. Additional analyses indicated that the apoptosis-inducing ligands, FasL and tumor necrosis factor (TNF), mediate this macrophage-induced apoptosis of CD4+ T cells. These results support a role for macrophage-associated FasL and TNF in the selective depletion of CD4+ T cells in HIV-infected individuals.

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A subclass of dendritic cells kills CD4 T cells via Fas/Fas-ligand-induced apoptosis.

Journal of Experimental Medicine ◽

10.1084/jem.183.4.1789 ◽

1996 ◽

Vol 183 (4) ◽

pp. 1789-1796 ◽

Cited By ~ 476

Author(s):

G Süss ◽

K Shortman

Keyword(s):

T Cells ◽

Dendritic Cells ◽

Cd4 T Cells ◽

Fas Ligand ◽

Activated T Cells ◽

T Cell Apoptosis ◽

Peripheral T Cells ◽

Surface Staining ◽

Induced Apoptosis ◽

Antigen Presenting

Dendritic cells (DC), the most efficient antigen-presenting cells, are well equipped for activation of naive CD4+ T cells by their expression of high levels of major histocompatibility complex and costimulator molecules. We now demonstrate that some DC are equally well equipped for killing these same T cells. Murine splenic DC consist of both conventional CD8alpha- DC and a major population of CD8alpha+ DC. Whereas CD8- DC induce a vigorous proliferative response in CD4 T cells, CD8+ DC induce a lesser response that is associated with marked T cell apoptosis. By using various mixtures of T cells and DC from Fas-mutant lpr/lpr mice and Fas-ligand (FasL) mutant gld/gld mice, we show this death is due to interaction of Fas on activated T cells with FasL on CD8+ DC. Furthermore, we show by direct surface staining that CD8+ DC, but not CD8- DC, express FasL at high levels. These findings indicate that FasL+ CD8+ DC are a specialized subgroup of DC with a role in the regulation of the response of primary peripheral T cells.

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TLR2 Signaling Renders Quiescent Naive and Memory CD4+T Cells More Susceptible to Productive Infection with X4 and R5 HIV-Type 1

The Journal of Immunology ◽

10.4049/jimmunol.179.7.4357 ◽

2007 ◽

Vol 179 (7) ◽

pp. 4357-4366 ◽

Cited By ~ 34

Author(s):

Sandra Thibault ◽

Mélanie R. Tardif ◽

Corinne Barat ◽

Michel J. Tremblay

Keyword(s):

T Cells ◽

Cd4 T Cells ◽

Productive Infection ◽

Hiv Type 1 ◽

Memory Cd4 T Cells ◽

Tlr2 Signaling

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CD4 T lymphocytes are primed to express Fas ligand by CD4 cross-linking and to contribute to CD8 T-cell apoptosis via Fas/FasL death signaling pathway

Blood ◽

10.1182/blood.v96.1.195.013k51_195_202 ◽

2000 ◽

Vol 96 (1) ◽

pp. 195-202 ◽

Cited By ~ 1

Author(s):

Masaki Tateyama ◽

Naoki Oyaizu ◽

Thomas W. McCloskey ◽

Soe Than ◽

Savita Pahwa

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cd4 T Cells ◽

Interleukin 2 ◽

Cd8 T Cell ◽

T Cell Subsets ◽

Cross Linking ◽

Induced Apoptosis ◽

Hiv 1

CD4 molecules serve as coreceptors for the T-cell receptor (TCR)/CD3 complex that are engaged coordinately with TCR and facilitate antigen-specific T-cell activation leading to interleukin 2 (IL-2) production and proliferation. However, cross-ligation of CD4 molecules prior to TCR stimulation has been shown to prime CD4 T cells to undergo apoptosis. Although in vivo and in vitro experiments have implicated the involvement of Fas/FasL interaction in this CD4 cross-linking (CD4XL)-induced apoptosis, detailed mechanisms to account for cell death induction have not been elucidated. In the present study, we demonstrate that CD4XL in purified T cells not only led to Fas up-regulation but also primed CD4 T cells to express FasL upon CD3 stimulation and rendered the T cells susceptible to Fas-mediated apoptosis. Notably, in addition to CD4+ T cells, CD4XL-induced sensitization for apoptosis was observed in CD8+ T cells as well and was associated with Bcl-x down-modulation. Both CD4 and CD8 T-cell subsets underwent apoptosis following cell–cell contact with FasL+ CD4 T cells. CD28 costimulation abrogated CD4XL/CD3-induced apoptosis with restoration of IL-2 production and prevented Bcl-x down-modulation. As CD4 molecules are the primary receptors for human immunodeficiency virus 1 (HIV-1), we conclude that HIV-1 envelope mediated CD4XL can lead to the generation of FasL-expressing CD4+ T cells that can lead to apoptosis of CD4 as well as CD8 T cells. These findings implicate a novel mechanism for CD8 T-cell depletion in HIV disease.

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Unstimulated Primary CD4+ T Cells from HIV-1-Positive Elite Suppressors Are Fully Susceptible to HIV-1 Entry and Productive Infection

Journal of Virology ◽

10.1128/jvi.01721-10 ◽

2010 ◽

Vol 85 (2) ◽

pp. 979-986 ◽

Cited By ~ 26

Author(s):

S. A. Rabi ◽

K. A. O'Connell ◽

D. Nikolaeva ◽

J. R. Bailey ◽

B. L. Jilek ◽

...

Keyword(s):

T Cells ◽

Cd4 T Cells ◽

Productive Infection ◽

Elite Suppressors ◽

Hiv 1

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Higher Bcl-2 levels decrease staphylococcal superantigen-induced apoptosis of CD4+T cells in atopic dermatitis

Allergy ◽

10.1111/j.1398-9995.2006.01297.x ◽

2007 ◽

Vol 62 (5) ◽

pp. 520-526 ◽

Cited By ~ 6

Author(s):

Y. T. Lin ◽

C. T. Wang ◽

J. H. Lee ◽

C. Y. Chu ◽

W. C. Tsao ◽

...

Keyword(s):

T Cells ◽

Atopic Dermatitis ◽

Cd4 T Cells ◽

Induced Apoptosis

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The C-type lectin surface receptor DCIR acts as a new attachment factor for HIV-1 in dendritic cells and contributes to trans- and cis-infection pathways

Blood ◽

10.1182/blood-2008-01-136473 ◽

2008 ◽

Vol 112 (4) ◽

pp. 1299-1307 ◽

Cited By ~ 125

Author(s):

Alexandra A. Lambert ◽

Caroline Gilbert ◽

Manon Richard ◽

André D. Beaulieu ◽

Michel J. Tremblay

Keyword(s):

T Cells ◽

Dendritic Cells ◽

Cd4 T Cells ◽

Productive Infection ◽

Virus Binding ◽

Virus Propagation ◽

Cell Surface Molecule ◽

Lectin Receptor ◽

Trans Infection ◽

Hiv 1

Abstract The dynamic interplay between dendritic cells (DCs) and human immunodeficiency virus type-1 (HIV-1) is thought to result in viral dissemination and evasion of antiviral immunity. Although initial observations suggested that the C-type lectin receptor (CLR) DC-SIGN was responsible for the trans-infection function of the virus, subsequent studies demonstrated that trans-infection of CD4+ T cells with HIV-1 can also occur through DC-SIGN–independent mechanisms. We demonstrate that a cell surface molecule designated DCIR (for DCimmunoreceptor), a member of a recently described family of DC-expressing CLRs, can participate in the capture of HIV-1 and promote infection in trans and in cis of autologous CD4+ T cells from human immature monocyte-derived DCs. The contribution of DCIR to these processes was revealed using DCIR-specific siRNAs and a polyclonal antibody specific for the carbohydrate recognition domain of DCIR. Data from transfection experiments indicated that DCIR acts as a ligand for HIV-1 and is involved in events leading to productive virus infection. Finally, we show that the neck domain of DCIR is important for the DCIR-mediated effect on virus binding and infection. These results point to a possible role for DCIR in HIV-1 pathogenesis by supporting the productive infection of DCs and promoting virus propagation.

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