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A role for S1P and S1P1 in immature-B cell egress from mouse bone marrow.

Pereira JP, Xu Y, Cyster JG - PLoS ONE (2010)

Bottom Line: B lymphocyte egress from secondary lymphoid organs requires sphingosine-1-phosphate (S1P) and S1P receptor-1 (S1P1).Transgenic expression of S1P1 in developing B cells was sufficient to mobilize pro- and pre-B cells from the BM.We conclude that the S1P1-S1P pathway contributes to egress of immature-B cells from BM, and that this mechanism is partially redundant with other undefined pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America. Joao.Pereira@ucsf.edu

ABSTRACT
B lymphocyte egress from secondary lymphoid organs requires sphingosine-1-phosphate (S1P) and S1P receptor-1 (S1P1). However, whether S1P contributes to immature-B cell egress from the bone marrow (BM) has not been fully assessed. Here we report that in S1P- and S1P1-conditionally deficient mice, the number of immature-B cells in the BM parenchyma increased, while it decreased in the blood. Moreover, a slower rate of bromodeoxyuridine incorporation suggested immature-B cells spent longer in the BM of mice in which S1P1-S1P signaling was genetically or pharmacologically impaired. Transgenic expression of S1P1 in developing B cells was sufficient to mobilize pro- and pre-B cells from the BM. We conclude that the S1P1-S1P pathway contributes to egress of immature-B cells from BM, and that this mechanism is partially redundant with other undefined pathways.

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Prolonged residence of immature-B cells in BM of S1P1 or S1P deficient mice.(A) Analysis of BrdU incorporation for 48 h in developing B cell subsets in chimeras reconstituted with mixtures of Edg1Fl/− Mb1Cre/+ (gray bars, Ly5.2+) or Edg1+/+ Mb1Cre/+ (white bars, Ly5.2+) with wild-type (Ly5.1+) BM. Shown is the ratio of percent BrdU+ Ly5.2+ and BrdU+ Ly5.1+ cells in the indicated developmental subsets. Data are pooled from 3 independent experiments. (B) BrdU incorporation for 48 h in developing B cell subsets from Sphk-1 and -2-deficient (gray bars) and littermate controls (white bars). Data shown were pooled from 2 independent experiments. (C) BrdU incorporation for 48 h in developing B cell subsets from mice treated with saline (white bars) or FTY720 (1 mg/Kg; gray bars) for 3 days. Data shown are representative of 3 independent experiments. In all panels, bars indicate the mean, circles indicate individual mice. * P<0.05; ** P<0.005 (unpaired, two-tailed Student's t-test).
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pone-0009277-g004: Prolonged residence of immature-B cells in BM of S1P1 or S1P deficient mice.(A) Analysis of BrdU incorporation for 48 h in developing B cell subsets in chimeras reconstituted with mixtures of Edg1Fl/− Mb1Cre/+ (gray bars, Ly5.2+) or Edg1+/+ Mb1Cre/+ (white bars, Ly5.2+) with wild-type (Ly5.1+) BM. Shown is the ratio of percent BrdU+ Ly5.2+ and BrdU+ Ly5.1+ cells in the indicated developmental subsets. Data are pooled from 3 independent experiments. (B) BrdU incorporation for 48 h in developing B cell subsets from Sphk-1 and -2-deficient (gray bars) and littermate controls (white bars). Data shown were pooled from 2 independent experiments. (C) BrdU incorporation for 48 h in developing B cell subsets from mice treated with saline (white bars) or FTY720 (1 mg/Kg; gray bars) for 3 days. Data shown are representative of 3 independent experiments. In all panels, bars indicate the mean, circles indicate individual mice. * P<0.05; ** P<0.005 (unpaired, two-tailed Student's t-test).

Mentions: If BM egress of developing B cells is defective then their time of residence in the BM might be increased. To explore this possibility we analyzed the rate of BrdU incorporation in BM B cell subsets of Edg1fl/− Mb1Cre/+ or Edg1+/+ Mb1Cre/+ (Ly5.1) and wild type (Ly5.2) mixed BM chimeras, and in Sphk-deficient and control littermates, by feeding them BrdU (1 mg/mL) in the drinking water. After 48 hours, the fraction of BrdU+ S1P1-deficient immature IgD− and IgDlo B cells was significantly reduced, as compared to the fraction of BrdU+ S1P1-sufficient immature-B cells (Figure 4A). Pre-B cells became similarly BrdU labeled in the two groups indicating that S1P1-signaling is not required for Pro-B and Pre-B cell expansion or survival. Thus, the reduced frequency of BrdU+ immature-B cells likely reflects an increase in the proportion of these cells that resided in BM for a period longer than the 48 h of continuous BrdU treatment. Sphk-deficient mice also showed lower 48 h BrdU labeling of IgDlo immature-B cells compared to littermate controls (Figure 4B). Similarly, in wild-type C57BL/6 mice treated with FTY720 for 3 days we found a reduced fraction of 24 h and 48 h BrdU-labeled immature-B cells (but not Pre-B cells) in BM parenchyma, sinusoids, blood and spleen (Table 1 and Figure 4C). The similar rate of BrdU incorporation at 24 h and 48 h in Pro-B and Pre-B cells suggests that the S1P/S1P-receptor pathway is not required during early stages of B cell development. However, these findings suggest a slower rate of immature-BM B cell replacement by newly generated cells, consistent with a role for the S1P-pathway in BM egress.


A role for S1P and S1P1 in immature-B cell egress from mouse bone marrow.

Pereira JP, Xu Y, Cyster JG - PLoS ONE (2010)

Prolonged residence of immature-B cells in BM of S1P1 or S1P deficient mice.(A) Analysis of BrdU incorporation for 48 h in developing B cell subsets in chimeras reconstituted with mixtures of Edg1Fl/− Mb1Cre/+ (gray bars, Ly5.2+) or Edg1+/+ Mb1Cre/+ (white bars, Ly5.2+) with wild-type (Ly5.1+) BM. Shown is the ratio of percent BrdU+ Ly5.2+ and BrdU+ Ly5.1+ cells in the indicated developmental subsets. Data are pooled from 3 independent experiments. (B) BrdU incorporation for 48 h in developing B cell subsets from Sphk-1 and -2-deficient (gray bars) and littermate controls (white bars). Data shown were pooled from 2 independent experiments. (C) BrdU incorporation for 48 h in developing B cell subsets from mice treated with saline (white bars) or FTY720 (1 mg/Kg; gray bars) for 3 days. Data shown are representative of 3 independent experiments. In all panels, bars indicate the mean, circles indicate individual mice. * P<0.05; ** P<0.005 (unpaired, two-tailed Student's t-test).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2823786&req=5

pone-0009277-g004: Prolonged residence of immature-B cells in BM of S1P1 or S1P deficient mice.(A) Analysis of BrdU incorporation for 48 h in developing B cell subsets in chimeras reconstituted with mixtures of Edg1Fl/− Mb1Cre/+ (gray bars, Ly5.2+) or Edg1+/+ Mb1Cre/+ (white bars, Ly5.2+) with wild-type (Ly5.1+) BM. Shown is the ratio of percent BrdU+ Ly5.2+ and BrdU+ Ly5.1+ cells in the indicated developmental subsets. Data are pooled from 3 independent experiments. (B) BrdU incorporation for 48 h in developing B cell subsets from Sphk-1 and -2-deficient (gray bars) and littermate controls (white bars). Data shown were pooled from 2 independent experiments. (C) BrdU incorporation for 48 h in developing B cell subsets from mice treated with saline (white bars) or FTY720 (1 mg/Kg; gray bars) for 3 days. Data shown are representative of 3 independent experiments. In all panels, bars indicate the mean, circles indicate individual mice. * P<0.05; ** P<0.005 (unpaired, two-tailed Student's t-test).
Mentions: If BM egress of developing B cells is defective then their time of residence in the BM might be increased. To explore this possibility we analyzed the rate of BrdU incorporation in BM B cell subsets of Edg1fl/− Mb1Cre/+ or Edg1+/+ Mb1Cre/+ (Ly5.1) and wild type (Ly5.2) mixed BM chimeras, and in Sphk-deficient and control littermates, by feeding them BrdU (1 mg/mL) in the drinking water. After 48 hours, the fraction of BrdU+ S1P1-deficient immature IgD− and IgDlo B cells was significantly reduced, as compared to the fraction of BrdU+ S1P1-sufficient immature-B cells (Figure 4A). Pre-B cells became similarly BrdU labeled in the two groups indicating that S1P1-signaling is not required for Pro-B and Pre-B cell expansion or survival. Thus, the reduced frequency of BrdU+ immature-B cells likely reflects an increase in the proportion of these cells that resided in BM for a period longer than the 48 h of continuous BrdU treatment. Sphk-deficient mice also showed lower 48 h BrdU labeling of IgDlo immature-B cells compared to littermate controls (Figure 4B). Similarly, in wild-type C57BL/6 mice treated with FTY720 for 3 days we found a reduced fraction of 24 h and 48 h BrdU-labeled immature-B cells (but not Pre-B cells) in BM parenchyma, sinusoids, blood and spleen (Table 1 and Figure 4C). The similar rate of BrdU incorporation at 24 h and 48 h in Pro-B and Pre-B cells suggests that the S1P/S1P-receptor pathway is not required during early stages of B cell development. However, these findings suggest a slower rate of immature-BM B cell replacement by newly generated cells, consistent with a role for the S1P-pathway in BM egress.

Bottom Line: B lymphocyte egress from secondary lymphoid organs requires sphingosine-1-phosphate (S1P) and S1P receptor-1 (S1P1).Transgenic expression of S1P1 in developing B cells was sufficient to mobilize pro- and pre-B cells from the BM.We conclude that the S1P1-S1P pathway contributes to egress of immature-B cells from BM, and that this mechanism is partially redundant with other undefined pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America. Joao.Pereira@ucsf.edu

ABSTRACT
B lymphocyte egress from secondary lymphoid organs requires sphingosine-1-phosphate (S1P) and S1P receptor-1 (S1P1). However, whether S1P contributes to immature-B cell egress from the bone marrow (BM) has not been fully assessed. Here we report that in S1P- and S1P1-conditionally deficient mice, the number of immature-B cells in the BM parenchyma increased, while it decreased in the blood. Moreover, a slower rate of bromodeoxyuridine incorporation suggested immature-B cells spent longer in the BM of mice in which S1P1-S1P signaling was genetically or pharmacologically impaired. Transgenic expression of S1P1 in developing B cells was sufficient to mobilize pro- and pre-B cells from the BM. We conclude that the S1P1-S1P pathway contributes to egress of immature-B cells from BM, and that this mechanism is partially redundant with other undefined pathways.

Show MeSH
Related in: MedlinePlus