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The granulocyte colony stimulating factor pathway regulates autoantibody production in a murine induced model of systemic lupus erythematosus.

Lantow M, Sivakumar R, Zeumer L, Wasserfall C, Zheng YY, Atkinson MA, Morel L - Arthritis Res. Ther. (2013)

Bottom Line: G-CSF binding by B6.Sle2c2 leukocytes was reduced as compared to B6, which was associated with a reduced expansion in response to in vivo G-CSF treatment.G-CSF in vivo treatment also failed to mobilize bone-marrow B6.Sle2c2 neutrophils as it did for B6 neutrophils.This result was corroborated by the increased anti-dsDNA IgG production in G-CSF-treated B6.TC mice, which also carry the Sle2c2 locus.

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ABSTRACT

Introduction: An NZB-derived genetic locus (Sle2c2) that suppresses autoantibody production in a mouse model of induced systemic lupus erythematosus contains a polymorphism in the gene encoding the G-CSF receptor. This study was designed to test the hypothesis that the Sle2c2 suppression is associated with an impaired G-CSF receptor function that can be overcome by exogenous G-CSF.

Methods: Leukocytes from B6.Sle2c2 and B6 congenic mice, which carry a different allele of the G-CSF receptor, were compared for their responses to G-CSF. Autoantibody production was induced with the chronic graft-versus-host-disease (cGVHD) model by adoptive transfer of B6.bm12 splenocytes. Different treatment regimens varying the amount and frequency of G-CSF (Neulasta®) or carrier control were tested on cGVHD outcomes. Autoantibody production, immune cell activation, and reactive oxygen species (ROS) production were compared between the two strains with the various treatments. In addition, the effect of G-CSF treatment was examined on the production autoantibodies in the B6.Sle1.Sle2.Sle3 (B6.TC) spontaneous model of lupus.

Results: B6.Sle2c2 and B6 leukocytes responded differently to G-CSF. G-CSF binding by B6.Sle2c2 leukocytes was reduced as compared to B6, which was associated with a reduced expansion in response to in vivo G-CSF treatment. G-CSF in vivo treatment also failed to mobilize bone-marrow B6.Sle2c2 neutrophils as it did for B6 neutrophils. In contrast, the expression of G-CSF responsive genes indicated a higher G-CSF receptor signaling in B6.Sle2c2 cells. G-CSF treatment restored the ability of B6.Sle2c2 mice to produce autoantibodies in a dose-dependent manner upon cGVHD induction, which correlated with restored CD4+ T cells activation, as well as dendritic cell and granulocyte expansion. Steady-state ROS production was higher in B6.Sle2c2 than in B6 mice. cGVHD induction resulted in a larger increase in ROS production in B6 than in B6.Sle2c2 mice, and this difference was eliminated with G-CSF treatment. Finally, a low dose G-CSF treatment accelerated the production of anti-dsDNA IgG in young B6.TC mice.

Conclusion: The different in vivo and in vitro responses of B6.Sle2c2 leukocytes are consistent with the mutation in the G-CSFR having functional consequences. The elimination of Sle2c2 suppression of autoantibody production by exogenous G-CSF indicates that Sle2c2 corresponds to a loss of function of G-CSF receptor. This result was corroborated by the increased anti-dsDNA IgG production in G-CSF-treated B6.TC mice, which also carry the Sle2c2 locus. Overall, these results suggest that the G-CSF pathway regulates the production of autoantibodies in murine models of lupus.

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Differential neutrophil mobilization in response to human granulocyte-colony stimulation factor (huG-CSF) in B6 and B6.Sle2c2 mice. Percentage of Ly6G+ CD11b+ neutrophils present in the bone marrow (BM) (A) and spleen (B) in B6 and B6.Sle2c2 mice 4 d after an injection with 5% dextrose (Dex) or 1 ug hu-G-CSF (GCSF). The graphs show mean and standard error of the mean with the significance of the Bonferroni multiple comparison test performed on three mice per group. The experiment was repeated and the same results were obtained, although with different absolute values (*P < 0.05; **P < 0.01; ***P < 0.001).
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Figure 2: Differential neutrophil mobilization in response to human granulocyte-colony stimulation factor (huG-CSF) in B6 and B6.Sle2c2 mice. Percentage of Ly6G+ CD11b+ neutrophils present in the bone marrow (BM) (A) and spleen (B) in B6 and B6.Sle2c2 mice 4 d after an injection with 5% dextrose (Dex) or 1 ug hu-G-CSF (GCSF). The graphs show mean and standard error of the mean with the significance of the Bonferroni multiple comparison test performed on three mice per group. The experiment was repeated and the same results were obtained, although with different absolute values (*P < 0.05; **P < 0.01; ***P < 0.001).

Mentions: One of the functions of G-CSF is to mobilize neutrophils from BM to the periphery [7]. We therefore compared the numbers of neutrophils in the BM and the spleen of B6 and B6.Sle2c2 mice 4 d after treatment with G-CSF or dextrose control (Figure 2). As expected, the percentage of neutrophils decreased in the BM of G-CSF-treated B6 mice (Figure 2A and 2C) and increased in their spleens (Figure 2B and 2C). In contrast, the percentage of neutrophils in the BM of G-CSF-treated B6.Sle2c2 mice was higher than in the BM of dextrose-treated mice (Figure 2A and 2C), which corresponded to a lack of mobilization of the B6.Sle2c2 neutrophils to the spleen (Figure 2B and 2C). The percentages of neutrophils in the blood of these G-GCF-treated mice reflected this difference in mobilization, with an increased percentage of circulating B6 neutrophils but a decreased percentage of circulating B6.Sle2c2 neutrophils (Figure 2D).


The granulocyte colony stimulating factor pathway regulates autoantibody production in a murine induced model of systemic lupus erythematosus.

Lantow M, Sivakumar R, Zeumer L, Wasserfall C, Zheng YY, Atkinson MA, Morel L - Arthritis Res. Ther. (2013)

Differential neutrophil mobilization in response to human granulocyte-colony stimulation factor (huG-CSF) in B6 and B6.Sle2c2 mice. Percentage of Ly6G+ CD11b+ neutrophils present in the bone marrow (BM) (A) and spleen (B) in B6 and B6.Sle2c2 mice 4 d after an injection with 5% dextrose (Dex) or 1 ug hu-G-CSF (GCSF). The graphs show mean and standard error of the mean with the significance of the Bonferroni multiple comparison test performed on three mice per group. The experiment was repeated and the same results were obtained, although with different absolute values (*P < 0.05; **P < 0.01; ***P < 0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672747&req=5

Figure 2: Differential neutrophil mobilization in response to human granulocyte-colony stimulation factor (huG-CSF) in B6 and B6.Sle2c2 mice. Percentage of Ly6G+ CD11b+ neutrophils present in the bone marrow (BM) (A) and spleen (B) in B6 and B6.Sle2c2 mice 4 d after an injection with 5% dextrose (Dex) or 1 ug hu-G-CSF (GCSF). The graphs show mean and standard error of the mean with the significance of the Bonferroni multiple comparison test performed on three mice per group. The experiment was repeated and the same results were obtained, although with different absolute values (*P < 0.05; **P < 0.01; ***P < 0.001).
Mentions: One of the functions of G-CSF is to mobilize neutrophils from BM to the periphery [7]. We therefore compared the numbers of neutrophils in the BM and the spleen of B6 and B6.Sle2c2 mice 4 d after treatment with G-CSF or dextrose control (Figure 2). As expected, the percentage of neutrophils decreased in the BM of G-CSF-treated B6 mice (Figure 2A and 2C) and increased in their spleens (Figure 2B and 2C). In contrast, the percentage of neutrophils in the BM of G-CSF-treated B6.Sle2c2 mice was higher than in the BM of dextrose-treated mice (Figure 2A and 2C), which corresponded to a lack of mobilization of the B6.Sle2c2 neutrophils to the spleen (Figure 2B and 2C). The percentages of neutrophils in the blood of these G-GCF-treated mice reflected this difference in mobilization, with an increased percentage of circulating B6 neutrophils but a decreased percentage of circulating B6.Sle2c2 neutrophils (Figure 2D).

Bottom Line: G-CSF binding by B6.Sle2c2 leukocytes was reduced as compared to B6, which was associated with a reduced expansion in response to in vivo G-CSF treatment.G-CSF in vivo treatment also failed to mobilize bone-marrow B6.Sle2c2 neutrophils as it did for B6 neutrophils.This result was corroborated by the increased anti-dsDNA IgG production in G-CSF-treated B6.TC mice, which also carry the Sle2c2 locus.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: An NZB-derived genetic locus (Sle2c2) that suppresses autoantibody production in a mouse model of induced systemic lupus erythematosus contains a polymorphism in the gene encoding the G-CSF receptor. This study was designed to test the hypothesis that the Sle2c2 suppression is associated with an impaired G-CSF receptor function that can be overcome by exogenous G-CSF.

Methods: Leukocytes from B6.Sle2c2 and B6 congenic mice, which carry a different allele of the G-CSF receptor, were compared for their responses to G-CSF. Autoantibody production was induced with the chronic graft-versus-host-disease (cGVHD) model by adoptive transfer of B6.bm12 splenocytes. Different treatment regimens varying the amount and frequency of G-CSF (Neulasta®) or carrier control were tested on cGVHD outcomes. Autoantibody production, immune cell activation, and reactive oxygen species (ROS) production were compared between the two strains with the various treatments. In addition, the effect of G-CSF treatment was examined on the production autoantibodies in the B6.Sle1.Sle2.Sle3 (B6.TC) spontaneous model of lupus.

Results: B6.Sle2c2 and B6 leukocytes responded differently to G-CSF. G-CSF binding by B6.Sle2c2 leukocytes was reduced as compared to B6, which was associated with a reduced expansion in response to in vivo G-CSF treatment. G-CSF in vivo treatment also failed to mobilize bone-marrow B6.Sle2c2 neutrophils as it did for B6 neutrophils. In contrast, the expression of G-CSF responsive genes indicated a higher G-CSF receptor signaling in B6.Sle2c2 cells. G-CSF treatment restored the ability of B6.Sle2c2 mice to produce autoantibodies in a dose-dependent manner upon cGVHD induction, which correlated with restored CD4+ T cells activation, as well as dendritic cell and granulocyte expansion. Steady-state ROS production was higher in B6.Sle2c2 than in B6 mice. cGVHD induction resulted in a larger increase in ROS production in B6 than in B6.Sle2c2 mice, and this difference was eliminated with G-CSF treatment. Finally, a low dose G-CSF treatment accelerated the production of anti-dsDNA IgG in young B6.TC mice.

Conclusion: The different in vivo and in vitro responses of B6.Sle2c2 leukocytes are consistent with the mutation in the G-CSFR having functional consequences. The elimination of Sle2c2 suppression of autoantibody production by exogenous G-CSF indicates that Sle2c2 corresponds to a loss of function of G-CSF receptor. This result was corroborated by the increased anti-dsDNA IgG production in G-CSF-treated B6.TC mice, which also carry the Sle2c2 locus. Overall, these results suggest that the G-CSF pathway regulates the production of autoantibodies in murine models of lupus.

Show MeSH
Related in: MedlinePlus