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Interleukin 7 signaling in dendritic cells regulates the homeostatic proliferation and niche size of CD4+ T cells.

Guimond M, Veenstra RG, Grindler DJ, Zhang H, Cui Y, Murphy RD, Kim SY, Na R, Hennighausen L, Kurtulus S, Erman B, Matzinger P, Merchant MS, Mackall CL - Nat. Immunol. (2009)

Bottom Line: However, it is not known why CD4(+) T cells undergo less-efficient homeostatic proliferation than CD8(+) T cells do.This effect was mediated at least in part by IL-7-mediated downregulation of the expression of major histocompatibility complex class II on IL-7Ralpha(+) DCs.Our results indicate that IL-7Ralpha(+) DCs are regulators of the peripheral CD4(+) T cell niche and that IL-7 signals in DCs prevent uncontrolled CD4(+) T cell population expansion in vivo.

View Article: PubMed Central - PubMed

Affiliation: Pediatric Oncology Branch, National Cancer Institute, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

ABSTRACT
Interleukin 7 (IL-7) and T cell antigen receptor signals have been proposed to be the main drivers of homeostatic T cell proliferation. However, it is not known why CD4(+) T cells undergo less-efficient homeostatic proliferation than CD8(+) T cells do. Here we show that systemic IL-7 concentrations increased during lymphopenia because of diminished use of IL-7 but that IL-7 signaling on IL-7 receptor-alpha-positive (IL-7Ralpha(+)) dendritic cells (DCs) in lymphopenic settings paradoxically diminished the homeostatic proliferation of CD4(+) T cells. This effect was mediated at least in part by IL-7-mediated downregulation of the expression of major histocompatibility complex class II on IL-7Ralpha(+) DCs. Our results indicate that IL-7Ralpha(+) DCs are regulators of the peripheral CD4(+) T cell niche and that IL-7 signals in DCs prevent uncontrolled CD4(+) T cell population expansion in vivo.

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IL-7Rα signaling regulates stromal IL-7 production in vivo. (a) IL-7 concentrations in serum (mean pg/ml of blood for triplicate wells) from indicated mice measured by 2E8 cell proliferation. Dashed line denotes limit of detection. *, P < 0.005 Blood was pooled from 4 mice, two independent experiments. (b) Left, IL-7Rα expression on congenic T cells 24 h after transfer into wild-type (WT) or Rag1-/- mice. Right, IL-7Rα MFI on congenic CD4 (black bars) and CD8 (white bars) T cells transferred into indicated recipients. *, P < 0.0001. Results are expressed as mean IL-7Rα (MFI), (n=4-5/group, 3 independent experiments). (c) IL-7 mRNA expression in splenic stroma of indicated mice, as measure by RT-PCR. Horizontal line indicates mean, and each dot represents an individual mouse. *, P < 0.0001. (d) Wild-type and Il7r-/- mice were treated with PBS or rhIL-7 (10μg/day) for 3 d (n=4/group), and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. of 4 mice/group, two independent experiments. *, P<0.0005. (e) Rag1-/- mice were treated with PBS or anti-IL-7 (M25) plus anti-IL-7Rα (A7R34) (1mg/day) for 3 d, and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. for 3 mice/group. (f) Fluorescence microscopy of the spleen capsule of wild-type mice (control) and mice expressing GFP downstream of the IL-7Rα promoter. Results are representative of two independent experiments. Two GFP transgenic mice and one WT control were analyzed in two independent experiments.
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Figure 1: IL-7Rα signaling regulates stromal IL-7 production in vivo. (a) IL-7 concentrations in serum (mean pg/ml of blood for triplicate wells) from indicated mice measured by 2E8 cell proliferation. Dashed line denotes limit of detection. *, P < 0.005 Blood was pooled from 4 mice, two independent experiments. (b) Left, IL-7Rα expression on congenic T cells 24 h after transfer into wild-type (WT) or Rag1-/- mice. Right, IL-7Rα MFI on congenic CD4 (black bars) and CD8 (white bars) T cells transferred into indicated recipients. *, P < 0.0001. Results are expressed as mean IL-7Rα (MFI), (n=4-5/group, 3 independent experiments). (c) IL-7 mRNA expression in splenic stroma of indicated mice, as measure by RT-PCR. Horizontal line indicates mean, and each dot represents an individual mouse. *, P < 0.0001. (d) Wild-type and Il7r-/- mice were treated with PBS or rhIL-7 (10μg/day) for 3 d (n=4/group), and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. of 4 mice/group, two independent experiments. *, P<0.0005. (e) Rag1-/- mice were treated with PBS or anti-IL-7 (M25) plus anti-IL-7Rα (A7R34) (1mg/day) for 3 d, and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. for 3 mice/group. (f) Fluorescence microscopy of the spleen capsule of wild-type mice (control) and mice expressing GFP downstream of the IL-7Rα promoter. Results are representative of two independent experiments. Two GFP transgenic mice and one WT control were analyzed in two independent experiments.

Mentions: In humans16-18 and other primates19, lymphopenia is associated with increased concentrations of IL-7 in the circulation and in tissues. However, whether a similar link between lymphopenia and IL-7 exists in mice is not known. Using commercial ELISA kits that can measure IL-7 in quantities as low as 30 pg/ml, we detected approximately 40 pg/ml IL-7 in the serum of Il7r-/- mice, but we did not detect IL-7 in the serum of Rag1-/- or wild-type mice (data not shown). Using a bioassay based upon proliferation of an IL-7- dependent cell line that could reliably measure IL-7 concentrations as low as 10 pg/ml (Supplementary Fig. 1a, online), we detected 10 pg/ml, 25 pg/ml and 40 pg/ml IL-7 in the serum of wild-type, Rag1-/- and Il7r-/- mice, respectively (Fig. 1a). A second bioassay based upon IL-7-mediated downregulation of IL-7Rα (http://www.signaling-gateway.org/molecule/query?afcsid=A001267)20 demonstrated that congenic lymphocytes transferred into Rag1-/- or Il7r-/- recipients (Fig. 1b and data not shown) expressed significantly lower amounts of surface IL-7Rα compared to lymphocytes transferred into wild-type or Il7-/- recipients. This was not due to proliferation-associated downregulation of IL-7Rα in response to lymphopenia, as CFSE staining showed no proliferation at the 24 h time point used for these studies (data not shown); this IL-7Rα downregulation was also not due to IL-7-mediated blockade of anti-IL-7Rα binding to IL-7Rα (Supplementary Fig. 1b, online). Reduced IL-7Rα protein expression was accompanied by diminished expression of IL-7Rα mRNA, as reported previously (data not shown)20. These data confirm that lymphopenic mice, like lymphopenic primates16-19, exhibit elevated IL-7 concentrations. In addition these findings reveal that IL-7 quantities are higher in Il7r-/- mice than in similarly lymphopenic Rag1-/- mice, raising the prospect that IL-7Rα contributes to the regulation of IL-7 production.


Interleukin 7 signaling in dendritic cells regulates the homeostatic proliferation and niche size of CD4+ T cells.

Guimond M, Veenstra RG, Grindler DJ, Zhang H, Cui Y, Murphy RD, Kim SY, Na R, Hennighausen L, Kurtulus S, Erman B, Matzinger P, Merchant MS, Mackall CL - Nat. Immunol. (2009)

IL-7Rα signaling regulates stromal IL-7 production in vivo. (a) IL-7 concentrations in serum (mean pg/ml of blood for triplicate wells) from indicated mice measured by 2E8 cell proliferation. Dashed line denotes limit of detection. *, P < 0.005 Blood was pooled from 4 mice, two independent experiments. (b) Left, IL-7Rα expression on congenic T cells 24 h after transfer into wild-type (WT) or Rag1-/- mice. Right, IL-7Rα MFI on congenic CD4 (black bars) and CD8 (white bars) T cells transferred into indicated recipients. *, P < 0.0001. Results are expressed as mean IL-7Rα (MFI), (n=4-5/group, 3 independent experiments). (c) IL-7 mRNA expression in splenic stroma of indicated mice, as measure by RT-PCR. Horizontal line indicates mean, and each dot represents an individual mouse. *, P < 0.0001. (d) Wild-type and Il7r-/- mice were treated with PBS or rhIL-7 (10μg/day) for 3 d (n=4/group), and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. of 4 mice/group, two independent experiments. *, P<0.0005. (e) Rag1-/- mice were treated with PBS or anti-IL-7 (M25) plus anti-IL-7Rα (A7R34) (1mg/day) for 3 d, and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. for 3 mice/group. (f) Fluorescence microscopy of the spleen capsule of wild-type mice (control) and mice expressing GFP downstream of the IL-7Rα promoter. Results are representative of two independent experiments. Two GFP transgenic mice and one WT control were analyzed in two independent experiments.
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Figure 1: IL-7Rα signaling regulates stromal IL-7 production in vivo. (a) IL-7 concentrations in serum (mean pg/ml of blood for triplicate wells) from indicated mice measured by 2E8 cell proliferation. Dashed line denotes limit of detection. *, P < 0.005 Blood was pooled from 4 mice, two independent experiments. (b) Left, IL-7Rα expression on congenic T cells 24 h after transfer into wild-type (WT) or Rag1-/- mice. Right, IL-7Rα MFI on congenic CD4 (black bars) and CD8 (white bars) T cells transferred into indicated recipients. *, P < 0.0001. Results are expressed as mean IL-7Rα (MFI), (n=4-5/group, 3 independent experiments). (c) IL-7 mRNA expression in splenic stroma of indicated mice, as measure by RT-PCR. Horizontal line indicates mean, and each dot represents an individual mouse. *, P < 0.0001. (d) Wild-type and Il7r-/- mice were treated with PBS or rhIL-7 (10μg/day) for 3 d (n=4/group), and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. of 4 mice/group, two independent experiments. *, P<0.0005. (e) Rag1-/- mice were treated with PBS or anti-IL-7 (M25) plus anti-IL-7Rα (A7R34) (1mg/day) for 3 d, and IL-7 mRNA expression by the stroma was measured by RT-PCR. Data show mean ±s.e. for 3 mice/group. (f) Fluorescence microscopy of the spleen capsule of wild-type mice (control) and mice expressing GFP downstream of the IL-7Rα promoter. Results are representative of two independent experiments. Two GFP transgenic mice and one WT control were analyzed in two independent experiments.
Mentions: In humans16-18 and other primates19, lymphopenia is associated with increased concentrations of IL-7 in the circulation and in tissues. However, whether a similar link between lymphopenia and IL-7 exists in mice is not known. Using commercial ELISA kits that can measure IL-7 in quantities as low as 30 pg/ml, we detected approximately 40 pg/ml IL-7 in the serum of Il7r-/- mice, but we did not detect IL-7 in the serum of Rag1-/- or wild-type mice (data not shown). Using a bioassay based upon proliferation of an IL-7- dependent cell line that could reliably measure IL-7 concentrations as low as 10 pg/ml (Supplementary Fig. 1a, online), we detected 10 pg/ml, 25 pg/ml and 40 pg/ml IL-7 in the serum of wild-type, Rag1-/- and Il7r-/- mice, respectively (Fig. 1a). A second bioassay based upon IL-7-mediated downregulation of IL-7Rα (http://www.signaling-gateway.org/molecule/query?afcsid=A001267)20 demonstrated that congenic lymphocytes transferred into Rag1-/- or Il7r-/- recipients (Fig. 1b and data not shown) expressed significantly lower amounts of surface IL-7Rα compared to lymphocytes transferred into wild-type or Il7-/- recipients. This was not due to proliferation-associated downregulation of IL-7Rα in response to lymphopenia, as CFSE staining showed no proliferation at the 24 h time point used for these studies (data not shown); this IL-7Rα downregulation was also not due to IL-7-mediated blockade of anti-IL-7Rα binding to IL-7Rα (Supplementary Fig. 1b, online). Reduced IL-7Rα protein expression was accompanied by diminished expression of IL-7Rα mRNA, as reported previously (data not shown)20. These data confirm that lymphopenic mice, like lymphopenic primates16-19, exhibit elevated IL-7 concentrations. In addition these findings reveal that IL-7 quantities are higher in Il7r-/- mice than in similarly lymphopenic Rag1-/- mice, raising the prospect that IL-7Rα contributes to the regulation of IL-7 production.

Bottom Line: However, it is not known why CD4(+) T cells undergo less-efficient homeostatic proliferation than CD8(+) T cells do.This effect was mediated at least in part by IL-7-mediated downregulation of the expression of major histocompatibility complex class II on IL-7Ralpha(+) DCs.Our results indicate that IL-7Ralpha(+) DCs are regulators of the peripheral CD4(+) T cell niche and that IL-7 signals in DCs prevent uncontrolled CD4(+) T cell population expansion in vivo.

View Article: PubMed Central - PubMed

Affiliation: Pediatric Oncology Branch, National Cancer Institute, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

ABSTRACT
Interleukin 7 (IL-7) and T cell antigen receptor signals have been proposed to be the main drivers of homeostatic T cell proliferation. However, it is not known why CD4(+) T cells undergo less-efficient homeostatic proliferation than CD8(+) T cells do. Here we show that systemic IL-7 concentrations increased during lymphopenia because of diminished use of IL-7 but that IL-7 signaling on IL-7 receptor-alpha-positive (IL-7Ralpha(+)) dendritic cells (DCs) in lymphopenic settings paradoxically diminished the homeostatic proliferation of CD4(+) T cells. This effect was mediated at least in part by IL-7-mediated downregulation of the expression of major histocompatibility complex class II on IL-7Ralpha(+) DCs. Our results indicate that IL-7Ralpha(+) DCs are regulators of the peripheral CD4(+) T cell niche and that IL-7 signals in DCs prevent uncontrolled CD4(+) T cell population expansion in vivo.

Show MeSH
Related in: MedlinePlus