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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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Dose-dependent apoptosis induction with Dex, MPA, NET-A and P4 in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), Dex, MPA, NET-A or P4 at the concentrations indicated for 24 hrs at 37°C. Cells were stained and analysed as described for Figure 1. The figure shows pooled results from two independent experiments with samples from three donors. Error bars represent standard deviation. Statistical trend analysis for each dose response was performed by the Wilcox rank-sum test, as further extended by Cuzick [85], and showed a significant trend only for Dex (p<0.001) and MPA (p = 0.047).
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pone-0062895-g003: Dose-dependent apoptosis induction with Dex, MPA, NET-A and P4 in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), Dex, MPA, NET-A or P4 at the concentrations indicated for 24 hrs at 37°C. Cells were stained and analysed as described for Figure 1. The figure shows pooled results from two independent experiments with samples from three donors. Error bars represent standard deviation. Statistical trend analysis for each dose response was performed by the Wilcox rank-sum test, as further extended by Cuzick [85], and showed a significant trend only for Dex (p<0.001) and MPA (p = 0.047).

Mentions: Having established that both MPA and Dex induce apoptosis in CD4+ T-cells, we next sought to determine whether this pro-apoptotic effect was dose-dependent. Statistically significant trends [85] were observed for Dex (p<0.001) and MPA (p = 0.047), but not for P4 or NET-A, showing increased apoptosis with increasing concentrations of ligand, in the absence of Vpr, under these experimental conditions (Figure 3). Furthermore, apoptotic induction in response to both Dex and MPA was observed, starting at concentrations as low as 10 nM (Figure 3). The maximal apoptotic response observed for both Dex and MPA was reached at 100 nM, and the maximal response for MPA (∼1.3-fold) at that concentration was lower than for Dex (∼2.3-fold) (Figure 3). Note that the fold induction of apoptosis with MPA under these conditions varies between experiments from about 1.3- to 1.7-fold (Figures 1,2,3), most likely due to biological variability between donors. Even though no dose-dependent significant trend for changes in apoptosis was observed for NET-A or P4, a small response (∼1.1-fold) appeared to occur for P4 at 1 µM. These results are similar to dose-responses observed with these ligands for transcriptional regulation via the GR, with Dex acting as a full agonist and MPA as a partial agonist for the GR at concentrations between 1–100 nM, but with NET-A showing no agonist activity and P4 very weak to partial agonist activity in some contexts only at micromolar concentrations [31], [34]. Having established that both Dex and MPA induce apoptosis in the CD4+ T-cells in a dose-dependent manner, we next sought to determine if Dex and MPA can enhance Vpr-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)

Dose-dependent apoptosis induction with Dex, MPA, NET-A and P4 in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), Dex, MPA, NET-A or P4 at the concentrations indicated for 24 hrs at 37°C. Cells were stained and analysed as described for Figure 1. The figure shows pooled results from two independent experiments with samples from three donors. Error bars represent standard deviation. Statistical trend analysis for each dose response was performed by the Wilcox rank-sum test, as further extended by Cuzick [85], and showed a significant trend only for Dex (p<0.001) and MPA (p = 0.047).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0062895-g003: Dose-dependent apoptosis induction with Dex, MPA, NET-A and P4 in CD4+ T-cells.PBMCs were treated with vehicle (EtOH), Dex, MPA, NET-A or P4 at the concentrations indicated for 24 hrs at 37°C. Cells were stained and analysed as described for Figure 1. The figure shows pooled results from two independent experiments with samples from three donors. Error bars represent standard deviation. Statistical trend analysis for each dose response was performed by the Wilcox rank-sum test, as further extended by Cuzick [85], and showed a significant trend only for Dex (p<0.001) and MPA (p = 0.047).
Mentions: Having established that both MPA and Dex induce apoptosis in CD4+ T-cells, we next sought to determine whether this pro-apoptotic effect was dose-dependent. Statistically significant trends [85] were observed for Dex (p<0.001) and MPA (p = 0.047), but not for P4 or NET-A, showing increased apoptosis with increasing concentrations of ligand, in the absence of Vpr, under these experimental conditions (Figure 3). Furthermore, apoptotic induction in response to both Dex and MPA was observed, starting at concentrations as low as 10 nM (Figure 3). The maximal apoptotic response observed for both Dex and MPA was reached at 100 nM, and the maximal response for MPA (∼1.3-fold) at that concentration was lower than for Dex (∼2.3-fold) (Figure 3). Note that the fold induction of apoptosis with MPA under these conditions varies between experiments from about 1.3- to 1.7-fold (Figures 1,2,3), most likely due to biological variability between donors. Even though no dose-dependent significant trend for changes in apoptosis was observed for NET-A or P4, a small response (∼1.1-fold) appeared to occur for P4 at 1 µM. These results are similar to dose-responses observed with these ligands for transcriptional regulation via the GR, with Dex acting as a full agonist and MPA as a partial agonist for the GR at concentrations between 1–100 nM, but with NET-A showing no agonist activity and P4 very weak to partial agonist activity in some contexts only at micromolar concentrations [31], [34]. Having established that both Dex and MPA induce apoptosis in the CD4+ T-cells in a dose-dependent manner, we next sought to determine if Dex and MPA can enhance Vpr-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