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The BMP Pathway Participates in Human Naive CD4+ T Cell Activation and Homeostasis.

Martínez VG, Sacedón R, Hidalgo L, Valencia J, Fernández-Sevilla LM, Hernández-López C, Vicente A, Varas A - PLoS ONE (2015)

Bottom Line: Blockade of BMP signaling severely impairs CD4+ T cell proliferation after activation mainly through regulation of IL-2, since the addition of this cytokine recuperates normal T cell expansion after inhibition of BMP signaling.Similarly, activation of canonical BMP pathway is required for both the maintenance of cell survival and the homeostatic proliferation induced by IL-7, a key factor for T cell homeostasis.Collectively, we describe important roles of the canonical BMP signaling in human naive CD4+ T cell activation and homeostasis that could be valuable for clinical application.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Faculty of Medicine, Complutense University, Madrid, Spain.

ABSTRACT
Bone Morphogenetic Proteins (BMPs) form a group of secreted factors that belongs to the TGF-β superfamily. Among different roles in a number of immune cell types, BMPs are known to regulate T cell development within the thymus, although the role of BMP signaling in human mature T cells remains elusive. In this study, we demonstrate that canonical BMP signaling is necessary during two critical events that regulate the size and function of human naive CD4+ T cell population: activation and homeostasis. Upon stimulation via TCR, naive CD4+ T cells upregulate the expression of BMP ligands triggering canonical BMP signaling in CD25+ cells. Blockade of BMP signaling severely impairs CD4+ T cell proliferation after activation mainly through regulation of IL-2, since the addition of this cytokine recuperates normal T cell expansion after inhibition of BMP signaling. Similarly, activation of canonical BMP pathway is required for both the maintenance of cell survival and the homeostatic proliferation induced by IL-7, a key factor for T cell homeostasis. Moreover, upregulation of two critical receptors for T cell homeostasis, CXCR4 and CCR9, triggered by IL-7 is also abrogated in the absence of BMP signaling. Collectively, we describe important roles of the canonical BMP signaling in human naive CD4+ T cell activation and homeostasis that could be valuable for clinical application.

No MeSH data available.


Related in: MedlinePlus

BMP signaling is activated by TCR stimulation in naive CD4+ T cells.Freshly isolated human peripheral blood naive CD4+ T cells were stimulated with anti-CD3/CD28 mAb. (A) Transcripts for several components of the canonical BMP signaling pathway were determined by real-time PCR ex vivo (0h) or after 6 days of stimulation (6d). GNB2L1 was used as endogenous control. Means ± SD of at least three independent experiments run in duplicates are shown. Note the logarithmic scale on y-axis. (B) Percentage of BMPRIA+ cells detected by flow cytometry throughout the culture. Bars represent the mean ± SD of two to five independent experiments. (C) Expression of BMPRIA and CD25 in T cells (upper dot plots) and differential expression of BMPRIA in the CD25- and CD25+ cell populations (lower histograms) during activation. A representative experiment out of four is shown. (D) Expression of BMPRIA in T cells cultured with different stimuli. Grey histograms represent isotype controls. Similar stainings were obtained in two to three independent experiments. mDCs: mature dendritic cells; PHA: Phytohaemagglutinin; Ck: cytokine cocktail (rhIL-2, rhIL-6, rhTNF-α) (E) Determination of BMP2/4 and BMP6 production by flow cytometry in T cells cultured in media alone (grey histograms) or in the presence of anti-CD3/CD28 mAb (black histograms). Grey filled histograms represent isotype control stainings. A representative experiment out of three is shown. (F) Expression of CD25 and phosphorylated BR-Smad (pBR-Smads) during activation. For comparison, T cells were kept in culture media alone. Results are representative of three independent experiments.
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pone.0131453.g001: BMP signaling is activated by TCR stimulation in naive CD4+ T cells.Freshly isolated human peripheral blood naive CD4+ T cells were stimulated with anti-CD3/CD28 mAb. (A) Transcripts for several components of the canonical BMP signaling pathway were determined by real-time PCR ex vivo (0h) or after 6 days of stimulation (6d). GNB2L1 was used as endogenous control. Means ± SD of at least three independent experiments run in duplicates are shown. Note the logarithmic scale on y-axis. (B) Percentage of BMPRIA+ cells detected by flow cytometry throughout the culture. Bars represent the mean ± SD of two to five independent experiments. (C) Expression of BMPRIA and CD25 in T cells (upper dot plots) and differential expression of BMPRIA in the CD25- and CD25+ cell populations (lower histograms) during activation. A representative experiment out of four is shown. (D) Expression of BMPRIA in T cells cultured with different stimuli. Grey histograms represent isotype controls. Similar stainings were obtained in two to three independent experiments. mDCs: mature dendritic cells; PHA: Phytohaemagglutinin; Ck: cytokine cocktail (rhIL-2, rhIL-6, rhTNF-α) (E) Determination of BMP2/4 and BMP6 production by flow cytometry in T cells cultured in media alone (grey histograms) or in the presence of anti-CD3/CD28 mAb (black histograms). Grey filled histograms represent isotype control stainings. A representative experiment out of three is shown. (F) Expression of CD25 and phosphorylated BR-Smad (pBR-Smads) during activation. For comparison, T cells were kept in culture media alone. Results are representative of three independent experiments.

Mentions: To investigate whether BMP signaling is activated in naive CD4+ T cells by TCR stimulation, we first analyzed the expression of several components of the canonical BMP pathway. We detected on freshly isolated naive CD4+ T cells the expression of the specific downstream effector molecules for the BMP signaling pathway, Smad-1, and -5, as well as the common Smad or Smad-4, that were also present after 6 days of activation with anti-CD3/CD28 mAbs (Fig 1A). In addition, transcription of the specific BMP receptors type I (BMPRIA, BMPRIB and ActRIA) and Smad-8 was induced in activated T cells while levels for the pseudoreceptor BAMBI were decreased compared with ex vivo (Fig 1A).


The BMP Pathway Participates in Human Naive CD4+ T Cell Activation and Homeostasis.

Martínez VG, Sacedón R, Hidalgo L, Valencia J, Fernández-Sevilla LM, Hernández-López C, Vicente A, Varas A - PLoS ONE (2015)

BMP signaling is activated by TCR stimulation in naive CD4+ T cells.Freshly isolated human peripheral blood naive CD4+ T cells were stimulated with anti-CD3/CD28 mAb. (A) Transcripts for several components of the canonical BMP signaling pathway were determined by real-time PCR ex vivo (0h) or after 6 days of stimulation (6d). GNB2L1 was used as endogenous control. Means ± SD of at least three independent experiments run in duplicates are shown. Note the logarithmic scale on y-axis. (B) Percentage of BMPRIA+ cells detected by flow cytometry throughout the culture. Bars represent the mean ± SD of two to five independent experiments. (C) Expression of BMPRIA and CD25 in T cells (upper dot plots) and differential expression of BMPRIA in the CD25- and CD25+ cell populations (lower histograms) during activation. A representative experiment out of four is shown. (D) Expression of BMPRIA in T cells cultured with different stimuli. Grey histograms represent isotype controls. Similar stainings were obtained in two to three independent experiments. mDCs: mature dendritic cells; PHA: Phytohaemagglutinin; Ck: cytokine cocktail (rhIL-2, rhIL-6, rhTNF-α) (E) Determination of BMP2/4 and BMP6 production by flow cytometry in T cells cultured in media alone (grey histograms) or in the presence of anti-CD3/CD28 mAb (black histograms). Grey filled histograms represent isotype control stainings. A representative experiment out of three is shown. (F) Expression of CD25 and phosphorylated BR-Smad (pBR-Smads) during activation. For comparison, T cells were kept in culture media alone. Results are representative of three independent experiments.
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pone.0131453.g001: BMP signaling is activated by TCR stimulation in naive CD4+ T cells.Freshly isolated human peripheral blood naive CD4+ T cells were stimulated with anti-CD3/CD28 mAb. (A) Transcripts for several components of the canonical BMP signaling pathway were determined by real-time PCR ex vivo (0h) or after 6 days of stimulation (6d). GNB2L1 was used as endogenous control. Means ± SD of at least three independent experiments run in duplicates are shown. Note the logarithmic scale on y-axis. (B) Percentage of BMPRIA+ cells detected by flow cytometry throughout the culture. Bars represent the mean ± SD of two to five independent experiments. (C) Expression of BMPRIA and CD25 in T cells (upper dot plots) and differential expression of BMPRIA in the CD25- and CD25+ cell populations (lower histograms) during activation. A representative experiment out of four is shown. (D) Expression of BMPRIA in T cells cultured with different stimuli. Grey histograms represent isotype controls. Similar stainings were obtained in two to three independent experiments. mDCs: mature dendritic cells; PHA: Phytohaemagglutinin; Ck: cytokine cocktail (rhIL-2, rhIL-6, rhTNF-α) (E) Determination of BMP2/4 and BMP6 production by flow cytometry in T cells cultured in media alone (grey histograms) or in the presence of anti-CD3/CD28 mAb (black histograms). Grey filled histograms represent isotype control stainings. A representative experiment out of three is shown. (F) Expression of CD25 and phosphorylated BR-Smad (pBR-Smads) during activation. For comparison, T cells were kept in culture media alone. Results are representative of three independent experiments.
Mentions: To investigate whether BMP signaling is activated in naive CD4+ T cells by TCR stimulation, we first analyzed the expression of several components of the canonical BMP pathway. We detected on freshly isolated naive CD4+ T cells the expression of the specific downstream effector molecules for the BMP signaling pathway, Smad-1, and -5, as well as the common Smad or Smad-4, that were also present after 6 days of activation with anti-CD3/CD28 mAbs (Fig 1A). In addition, transcription of the specific BMP receptors type I (BMPRIA, BMPRIB and ActRIA) and Smad-8 was induced in activated T cells while levels for the pseudoreceptor BAMBI were decreased compared with ex vivo (Fig 1A).

Bottom Line: Blockade of BMP signaling severely impairs CD4+ T cell proliferation after activation mainly through regulation of IL-2, since the addition of this cytokine recuperates normal T cell expansion after inhibition of BMP signaling.Similarly, activation of canonical BMP pathway is required for both the maintenance of cell survival and the homeostatic proliferation induced by IL-7, a key factor for T cell homeostasis.Collectively, we describe important roles of the canonical BMP signaling in human naive CD4+ T cell activation and homeostasis that could be valuable for clinical application.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Faculty of Medicine, Complutense University, Madrid, Spain.

ABSTRACT
Bone Morphogenetic Proteins (BMPs) form a group of secreted factors that belongs to the TGF-β superfamily. Among different roles in a number of immune cell types, BMPs are known to regulate T cell development within the thymus, although the role of BMP signaling in human mature T cells remains elusive. In this study, we demonstrate that canonical BMP signaling is necessary during two critical events that regulate the size and function of human naive CD4+ T cell population: activation and homeostasis. Upon stimulation via TCR, naive CD4+ T cells upregulate the expression of BMP ligands triggering canonical BMP signaling in CD25+ cells. Blockade of BMP signaling severely impairs CD4+ T cell proliferation after activation mainly through regulation of IL-2, since the addition of this cytokine recuperates normal T cell expansion after inhibition of BMP signaling. Similarly, activation of canonical BMP pathway is required for both the maintenance of cell survival and the homeostatic proliferation induced by IL-7, a key factor for T cell homeostasis. Moreover, upregulation of two critical receptors for T cell homeostasis, CXCR4 and CCR9, triggered by IL-7 is also abrogated in the absence of BMP signaling. Collectively, we describe important roles of the canonical BMP signaling in human naive CD4+ T cell activation and homeostasis that could be valuable for clinical application.

No MeSH data available.


Related in: MedlinePlus