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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 MPA- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), 100 nM MPA, 1 µM RU486 or 100 nM MPA plus 1 µM RU486, in the absence (A) or presence (B) of 5 µM Vpr peptide for 24 hrs. Cells were stained and acquired by flow cytometry as indicated in the methods. In A cells were not incubated with balanced isotonic glucose-HEPES buffer while in B, this buffer was used and a tryptic BSA digest served as a control wherever Vpr peptide was not added, as described in Methods. The histograms show 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. Error bars represent standard deviation.
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pone-0062895-g007: The GR is involved in MPA- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), 100 nM MPA, 1 µM RU486 or 100 nM MPA plus 1 µM RU486, in the absence (A) or presence (B) of 5 µM Vpr peptide for 24 hrs. Cells were stained and acquired by flow cytometry as indicated in the methods. In A cells were not incubated with balanced isotonic glucose-HEPES buffer while in B, this buffer was used and a tryptic BSA digest served as a control wherever Vpr peptide was not added, as described in Methods. The histograms show 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. Error bars represent standard deviation.

Mentions: Towards establishing a role for the GR in the MPA response, further experiments were performed with RU486, in the absence and presence of Vpr peptide (Figure 7). In the absence of prior incubation with peptide buffer (see methods), MPA significantly increased apoptosis compared to untreated CD4+ T-cells (Figure 7A), as previously shown (Figures 1,2,3). Importantly, although RU486 alone had no effect on apoptosis, this GR agonist could reverse MPA-mediated apoptosis in the CD4+ T-cells (Figure 7A) in a statistically significant manner. Vpr alone significantly induced apoptosis in CD4+ T-cells, and this response was decreased in the presence of RU486 (Figure 7A). Vpr and MPA in combination enhanced apoptosis by about 3-fold in a statistically significant manner, which was decreased by RU486 (Figure 7B). These results strongly suggest that MPA and Vpr alone or in combination, enhance apoptosis in CD4+ T-cells via a mechanism involving the GR. The lack of an effect by the natural PR ligand P4 or the synthetic progestin NET-A on Vpr-induced apoptosis is consistent with the requirement for GR agonist or strong partial agonist activity of a ligand to modulate Vpr-mediated apoptosis in CD4+ T-cells.


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 MPA- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), 100 nM MPA, 1 µM RU486 or 100 nM MPA plus 1 µM RU486, in the absence (A) or presence (B) of 5 µM Vpr peptide for 24 hrs. Cells were stained and acquired by flow cytometry as indicated in the methods. In A cells were not incubated with balanced isotonic glucose-HEPES buffer while in B, this buffer was used and a tryptic BSA digest served as a control wherever Vpr peptide was not added, as described in Methods. The histograms show 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. Error bars represent standard deviation.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0062895-g007: The GR is involved in MPA- and Vpr-mediated apoptosis in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), 100 nM MPA, 1 µM RU486 or 100 nM MPA plus 1 µM RU486, in the absence (A) or presence (B) of 5 µM Vpr peptide for 24 hrs. Cells were stained and acquired by flow cytometry as indicated in the methods. In A cells were not incubated with balanced isotonic glucose-HEPES buffer while in B, this buffer was used and a tryptic BSA digest served as a control wherever Vpr peptide was not added, as described in Methods. The histograms show 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. Error bars represent standard deviation.
Mentions: Towards establishing a role for the GR in the MPA response, further experiments were performed with RU486, in the absence and presence of Vpr peptide (Figure 7). In the absence of prior incubation with peptide buffer (see methods), MPA significantly increased apoptosis compared to untreated CD4+ T-cells (Figure 7A), as previously shown (Figures 1,2,3). Importantly, although RU486 alone had no effect on apoptosis, this GR agonist could reverse MPA-mediated apoptosis in the CD4+ T-cells (Figure 7A) in a statistically significant manner. Vpr alone significantly induced apoptosis in CD4+ T-cells, and this response was decreased in the presence of RU486 (Figure 7A). Vpr and MPA in combination enhanced apoptosis by about 3-fold in a statistically significant manner, which was decreased by RU486 (Figure 7B). These results strongly suggest that MPA and Vpr alone or in combination, enhance apoptosis in CD4+ T-cells via a mechanism involving the GR. The lack of an effect by the natural PR ligand P4 or the synthetic progestin NET-A on Vpr-induced apoptosis is consistent with the requirement for GR agonist or strong partial agonist activity of a ligand to modulate Vpr-mediated apoptosis in CD4+ T-cells.

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