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Patients with discordant responses to antiretroviral therapy have impaired killing of HIV-infected T cells.

Natesampillai S, Nie Z, Cummins NW, Jochmans D, Bren GD, Angel JB, Badley AD - PLoS Pathog. (2010)

Bottom Line: The reductions in cell death occurred both within infected cells, as well as in uninfected bystander cells.These data indicate that single point mutations within HIV protease which are selected in vivo can significantly impact the ability of HIV to kill CD4 T cells, while not impacting viral replication.Therefore, HIV protease regulates both HIV replication as well as HIV induced T cell depletion, the hallmark of HIV pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Mayo Clinic, Rochester, MN, USA.

ABSTRACT
In medicine, understanding the pathophysiologic basis of exceptional circumstances has led to an enhanced understanding of biology. We have studied the circumstance of HIV-infected patients in whom antiretroviral therapy results in immunologic benefit, despite virologic failure. In such patients, two protease mutations, I54V and V82A, occur more frequently. Expressing HIV protease containing these mutations resulted in less cell death, caspase activation, and nuclear fragmentation than wild type (WT) HIV protease or HIV protease containing other mutations. The impaired induction of cell death was also associated with impaired cleavage of procaspase 8, a requisite event for HIV protease mediated cell death. Primary CD4 T cells expressing I54V or V82A protease underwent less cell death than with WT or other mutant proteases. Human T cells infected with HIV containing these mutations underwent less cell death and less Casp8p41 production than WT or HIV containing other protease mutations, despite similar degrees of viral replication. The reductions in cell death occurred both within infected cells, as well as in uninfected bystander cells. These data indicate that single point mutations within HIV protease which are selected in vivo can significantly impact the ability of HIV to kill CD4 T cells, while not impacting viral replication. Therefore, HIV protease regulates both HIV replication as well as HIV induced T cell depletion, the hallmark of HIV pathogenesis.

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Reduced HIV-1PR-induced cell death is associated with reduced Casp8p41 production.YFP HIV protease or the indicated protease mutants were expressed in primary CD4 T cells and YFP positive cells were analyzed for Casp8p41 positivity (A, B). *Indicates p value ≤0.05. Data reflective of at least three independent replicates. Bars with solid color represent controls, bars with angled hatching represent Discordance Associated Mutations (DAMs), and bars with horizontal hatching represent non-DAMs.
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ppat-1001213-g007: Reduced HIV-1PR-induced cell death is associated with reduced Casp8p41 production.YFP HIV protease or the indicated protease mutants were expressed in primary CD4 T cells and YFP positive cells were analyzed for Casp8p41 positivity (A, B). *Indicates p value ≤0.05. Data reflective of at least three independent replicates. Bars with solid color represent controls, bars with angled hatching represent Discordance Associated Mutations (DAMs), and bars with horizontal hatching represent non-DAMs.

Mentions: Our previous publications indicate that HIV PR mediated killing requires procaspase 8 cleavage with subsequent generation of Casp8p41 [16]–[18]. Therefore, if our model holds, the impaired cell killing associated with I54V and V82A protease expression, should be associated with less Casp8p41 production. To test this hypothesis, we expressed mutant or WT HIV protease in primary CD4 T cells, and analyzed Casp8p41 production using a neoepitope specific Casp8p41 antibody [17]. Whereas expression of YFP WT protease in primary CD4 T cells resulted in a significant proportion of Casp8p41 positive cells, expression of either I54V or V82A resulted in significantly less Casp8p41 positivity than K20R, L63P, D30N, or L90M (Figure 7A, 7B).


Patients with discordant responses to antiretroviral therapy have impaired killing of HIV-infected T cells.

Natesampillai S, Nie Z, Cummins NW, Jochmans D, Bren GD, Angel JB, Badley AD - PLoS Pathog. (2010)

Reduced HIV-1PR-induced cell death is associated with reduced Casp8p41 production.YFP HIV protease or the indicated protease mutants were expressed in primary CD4 T cells and YFP positive cells were analyzed for Casp8p41 positivity (A, B). *Indicates p value ≤0.05. Data reflective of at least three independent replicates. Bars with solid color represent controls, bars with angled hatching represent Discordance Associated Mutations (DAMs), and bars with horizontal hatching represent non-DAMs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2991267&req=5

ppat-1001213-g007: Reduced HIV-1PR-induced cell death is associated with reduced Casp8p41 production.YFP HIV protease or the indicated protease mutants were expressed in primary CD4 T cells and YFP positive cells were analyzed for Casp8p41 positivity (A, B). *Indicates p value ≤0.05. Data reflective of at least three independent replicates. Bars with solid color represent controls, bars with angled hatching represent Discordance Associated Mutations (DAMs), and bars with horizontal hatching represent non-DAMs.
Mentions: Our previous publications indicate that HIV PR mediated killing requires procaspase 8 cleavage with subsequent generation of Casp8p41 [16]–[18]. Therefore, if our model holds, the impaired cell killing associated with I54V and V82A protease expression, should be associated with less Casp8p41 production. To test this hypothesis, we expressed mutant or WT HIV protease in primary CD4 T cells, and analyzed Casp8p41 production using a neoepitope specific Casp8p41 antibody [17]. Whereas expression of YFP WT protease in primary CD4 T cells resulted in a significant proportion of Casp8p41 positive cells, expression of either I54V or V82A resulted in significantly less Casp8p41 positivity than K20R, L63P, D30N, or L90M (Figure 7A, 7B).

Bottom Line: The reductions in cell death occurred both within infected cells, as well as in uninfected bystander cells.These data indicate that single point mutations within HIV protease which are selected in vivo can significantly impact the ability of HIV to kill CD4 T cells, while not impacting viral replication.Therefore, HIV protease regulates both HIV replication as well as HIV induced T cell depletion, the hallmark of HIV pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Mayo Clinic, Rochester, MN, USA.

ABSTRACT
In medicine, understanding the pathophysiologic basis of exceptional circumstances has led to an enhanced understanding of biology. We have studied the circumstance of HIV-infected patients in whom antiretroviral therapy results in immunologic benefit, despite virologic failure. In such patients, two protease mutations, I54V and V82A, occur more frequently. Expressing HIV protease containing these mutations resulted in less cell death, caspase activation, and nuclear fragmentation than wild type (WT) HIV protease or HIV protease containing other mutations. The impaired induction of cell death was also associated with impaired cleavage of procaspase 8, a requisite event for HIV protease mediated cell death. Primary CD4 T cells expressing I54V or V82A protease underwent less cell death than with WT or other mutant proteases. Human T cells infected with HIV containing these mutations underwent less cell death and less Casp8p41 production than WT or HIV containing other protease mutations, despite similar degrees of viral replication. The reductions in cell death occurred both within infected cells, as well as in uninfected bystander cells. These data indicate that single point mutations within HIV protease which are selected in vivo can significantly impact the ability of HIV to kill CD4 T cells, while not impacting viral replication. Therefore, HIV protease regulates both HIV replication as well as HIV induced T cell depletion, the hallmark of HIV pathogenesis.

Show MeSH
Related in: MedlinePlus