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The progestin-only contraceptive medroxyprogesterone acetate, but not norethisterone acetate, enhances HIV-1 Vpr-mediated apoptosis in human CD4+ T cells through the glucocorticoid receptor.

Tomasicchio M, Avenant C, Du Toit A, Ray RM, Hapgood JP - PLoS ONE (2013)

Bottom Line: These results, together with the findings that RU486, a GR antagonist, prevents Dex-, MPA- and Vpr-mediated apoptosis, provide evidence for the first time that GR agonists or partial agonists increase apoptosis in primary CD4(+) T-cells via the GR.This work suggests that contraceptive doses of MPA but not NET-A or physiological doses of progesterone could potentially accelerate depletion of CD4(+) T-cells in a GR-dependent fashion in HIV-1 positive women, thereby contributing to immunodeficiency.The results imply that choice of progestin used in contraception may be critical to susceptibility and progression of diseases such as HIV-1.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa.

ABSTRACT
The glucocorticoid receptor (GR) regulates several physiological functions, including immune function and apoptosis. The HIV-1 virus accessory protein, viral protein R (Vpr), can modulate the transcriptional response of the GR. Glucocorticoids (GCs) and Vpr have been reported to induce apoptosis in various cells, including T-cells. We have previously shown that the injectable contraceptive, medroxyprogesterone acetate (MPA) is a partial to full agonist for the GR, unlike norethisterone acetate (NET-A). We investigated the functional cross talk between the GR and Vpr in inducing apoptosis in CD4(+) T-cells, in the absence and presence of GCs and these progestins, as well as progesterone. By using flow cytometry, we show that, in contrast to NET-A and progesterone, the synthetic GR ligand dexamethasone (Dex), cortisol and MPA induce apoptosis in primary CD4(+) T-cells. Furthermore, the C-terminal part of the Vpr peptide, or HIV-1 pseudovirus, together with Dex or MPA further increased the apoptotic phenotype, unlike NET-A and progesterone. By a combination of Western blotting, PCR and the use of receptor- selective agonists, we provide evidence that the GR and the estrogen receptor are the only steroid receptors expressed in peripheral blood mononuclear cells. These results, together with the findings that RU486, a GR antagonist, prevents Dex-, MPA- and Vpr-mediated apoptosis, provide evidence for the first time that GR agonists or partial agonists increase apoptosis in primary CD4(+) T-cells via the GR. We show that apoptotic induction involves differential expression of key apoptotic genes by both Vpr and GCs/MPA. This work suggests that contraceptive doses of MPA but not NET-A or physiological doses of progesterone could potentially accelerate depletion of CD4(+) T-cells in a GR-dependent fashion in HIV-1 positive women, thereby contributing to immunodeficiency. The results imply that choice of progestin used in contraception may be critical to susceptibility and progression of diseases such as HIV-1.

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The GR is involved in GC- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with 100 nM Dex or 1 µM RU486 in the absence or presence of 5 µM Vpr peptide (amino acids 52–96) for 24 hrs. A tryptic BSA digest added at an equivalent mass/volume ratio of peptide, served as a control wherever Vpr peptide was present. Cells were obtained and stained as described in the methods. The histogram shows pooled results from two independent experiments with samples from three donors. Statistical significance was determined by one-way ANOVA with Dunnett’s post-test or a paired t-test, where *, **, and *** indicate p<0.05, 0.01 and 0.005 respectively.
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pone-0062895-g005: The GR is involved in GC- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with 100 nM Dex or 1 µM RU486 in the absence or presence of 5 µM Vpr peptide (amino acids 52–96) for 24 hrs. A tryptic BSA digest added at an equivalent mass/volume ratio of peptide, served as a control wherever Vpr peptide was present. Cells were obtained and stained as described in the methods. The histogram shows pooled results from two independent experiments with samples from three donors. Statistical significance was determined by one-way ANOVA with Dunnett’s post-test or a paired t-test, where *, **, and *** indicate p<0.05, 0.01 and 0.005 respectively.

Mentions: It is well established that Vpr is a potent inducer of apoptosis in a number of different cell lines and primary cells. Therefore, we determined whether exogenous C-terminal Vpr peptide could induce apoptosis via the GR in CD4+ T-cells. As expected, Vpr peptide significantly induced apoptosis by approximately 1.8-fold in the CD4+ T-cells (Figure 4). This apoptotic induction was decreased in the presence of RU486, a potent GR antagonist, indicating that the GR was involved in Vpr-mediated apoptosis (Figure 4). We next determined whether Dex could enhance Vpr-mediated apoptosis through the GR in CD4+ T-cells. Cells were incubated with Vpr peptide in the absence and presence of Dex. Vpr and Dex alone induced apoptosis in CD4+ T-cells, although statistical significance could not be established, most likely due to the small responses (Figure 5). Furthermore, when cells were treated with Dex and Vpr in combination, a significant increase in apoptosis was observed as compared to Vpr or Dex alone. To establish whether the GR was involved in combined effects of Vpr- and Dex-mediated apoptosis, cells were treated in the absence and presence of RU486. RU486 alone had no effect on apoptosis (Figures 4 and 5). Apoptosis by Dex and Vpr alone was decreased in the presence of RU486, although statistical significance could not be established. Importantly, the 3-fold increase in apoptosis observed when cells were treated with Dex and Vpr in combination was significantly decreased in the presence of RU486 (Figure 5). Although RU486 is also a PR and MR antagonist [29], our data discount a role for these receptors in apoptosis in these cells (Figure 2). Taken together, the data suggest that the GR is required for Vpr- and Dex-mediated apoptosis, and suggests that the GR is required for Vpr enhancement of Dex-mediated apoptosis.


The progestin-only contraceptive medroxyprogesterone acetate, but not norethisterone acetate, enhances HIV-1 Vpr-mediated apoptosis in human CD4+ T cells through the glucocorticoid receptor.

Tomasicchio M, Avenant C, Du Toit A, Ray RM, Hapgood JP - PLoS ONE (2013)

The GR is involved in GC- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with 100 nM Dex or 1 µM RU486 in the absence or presence of 5 µM Vpr peptide (amino acids 52–96) for 24 hrs. A tryptic BSA digest added at an equivalent mass/volume ratio of peptide, served as a control wherever Vpr peptide was present. Cells were obtained and stained as described in the methods. The histogram shows pooled results from two independent experiments with samples from three donors. Statistical significance was determined by one-way ANOVA with Dunnett’s post-test or a paired t-test, where *, **, and *** indicate p<0.05, 0.01 and 0.005 respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643923&req=5

pone-0062895-g005: The GR is involved in GC- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with 100 nM Dex or 1 µM RU486 in the absence or presence of 5 µM Vpr peptide (amino acids 52–96) for 24 hrs. A tryptic BSA digest added at an equivalent mass/volume ratio of peptide, served as a control wherever Vpr peptide was present. Cells were obtained and stained as described in the methods. The histogram shows pooled results from two independent experiments with samples from three donors. Statistical significance was determined by one-way ANOVA with Dunnett’s post-test or a paired t-test, where *, **, and *** indicate p<0.05, 0.01 and 0.005 respectively.
Mentions: It is well established that Vpr is a potent inducer of apoptosis in a number of different cell lines and primary cells. Therefore, we determined whether exogenous C-terminal Vpr peptide could induce apoptosis via the GR in CD4+ T-cells. As expected, Vpr peptide significantly induced apoptosis by approximately 1.8-fold in the CD4+ T-cells (Figure 4). This apoptotic induction was decreased in the presence of RU486, a potent GR antagonist, indicating that the GR was involved in Vpr-mediated apoptosis (Figure 4). We next determined whether Dex could enhance Vpr-mediated apoptosis through the GR in CD4+ T-cells. Cells were incubated with Vpr peptide in the absence and presence of Dex. Vpr and Dex alone induced apoptosis in CD4+ T-cells, although statistical significance could not be established, most likely due to the small responses (Figure 5). Furthermore, when cells were treated with Dex and Vpr in combination, a significant increase in apoptosis was observed as compared to Vpr or Dex alone. To establish whether the GR was involved in combined effects of Vpr- and Dex-mediated apoptosis, cells were treated in the absence and presence of RU486. RU486 alone had no effect on apoptosis (Figures 4 and 5). Apoptosis by Dex and Vpr alone was decreased in the presence of RU486, although statistical significance could not be established. Importantly, the 3-fold increase in apoptosis observed when cells were treated with Dex and Vpr in combination was significantly decreased in the presence of RU486 (Figure 5). Although RU486 is also a PR and MR antagonist [29], our data discount a role for these receptors in apoptosis in these cells (Figure 2). Taken together, the data suggest that the GR is required for Vpr- and Dex-mediated apoptosis, and suggests that the GR is required for Vpr enhancement of Dex-mediated apoptosis.

Bottom Line: These results, together with the findings that RU486, a GR antagonist, prevents Dex-, MPA- and Vpr-mediated apoptosis, provide evidence for the first time that GR agonists or partial agonists increase apoptosis in primary CD4(+) T-cells via the GR.This work suggests that contraceptive doses of MPA but not NET-A or physiological doses of progesterone could potentially accelerate depletion of CD4(+) T-cells in a GR-dependent fashion in HIV-1 positive women, thereby contributing to immunodeficiency.The results imply that choice of progestin used in contraception may be critical to susceptibility and progression of diseases such as HIV-1.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cell Biology, University of Cape Town, Cape Town, Western Province, South Africa.

ABSTRACT
The glucocorticoid receptor (GR) regulates several physiological functions, including immune function and apoptosis. The HIV-1 virus accessory protein, viral protein R (Vpr), can modulate the transcriptional response of the GR. Glucocorticoids (GCs) and Vpr have been reported to induce apoptosis in various cells, including T-cells. We have previously shown that the injectable contraceptive, medroxyprogesterone acetate (MPA) is a partial to full agonist for the GR, unlike norethisterone acetate (NET-A). We investigated the functional cross talk between the GR and Vpr in inducing apoptosis in CD4(+) T-cells, in the absence and presence of GCs and these progestins, as well as progesterone. By using flow cytometry, we show that, in contrast to NET-A and progesterone, the synthetic GR ligand dexamethasone (Dex), cortisol and MPA induce apoptosis in primary CD4(+) T-cells. Furthermore, the C-terminal part of the Vpr peptide, or HIV-1 pseudovirus, together with Dex or MPA further increased the apoptotic phenotype, unlike NET-A and progesterone. By a combination of Western blotting, PCR and the use of receptor- selective agonists, we provide evidence that the GR and the estrogen receptor are the only steroid receptors expressed in peripheral blood mononuclear cells. These results, together with the findings that RU486, a GR antagonist, prevents Dex-, MPA- and Vpr-mediated apoptosis, provide evidence for the first time that GR agonists or partial agonists increase apoptosis in primary CD4(+) T-cells via the GR. We show that apoptotic induction involves differential expression of key apoptotic genes by both Vpr and GCs/MPA. This work suggests that contraceptive doses of MPA but not NET-A or physiological doses of progesterone could potentially accelerate depletion of CD4(+) T-cells in a GR-dependent fashion in HIV-1 positive women, thereby contributing to immunodeficiency. The results imply that choice of progestin used in contraception may be critical to susceptibility and progression of diseases such as HIV-1.

Show MeSH
Related in: MedlinePlus