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Streptococcus pneumoniae serotype 1 capsular polysaccharide induces CD8CD28 regulatory T lymphocytes by TCR crosslinking.

Mertens J, Fabri M, Zingarelli A, Kubacki T, Meemboor S, Groneck L, Seeger J, Bessler M, Hafke H, Odenthal M, Bieler JG, Kalka C, Schneck JP, Kashkar H, Kalka-Moll WM - PLoS Pathog. (2009)

Bottom Line: The expansion of CD8(+)CD28(-) T cells is independent, of direct antigen-presenting cell/T cell contact and, to the specificity of the T cell receptor (TCR).In CD8(+)CD28(-) T cells, Sp1 enhances Zap-70 phosphorylation and increasingly involves NF-kappaB which ultimately results in protection versus apoptosis and cell death and promotes survival and accumulation of the CD8(+)CD28(-) population.The underlying mechanism of CD8(+) T cell activation appears to rely on enhanced TCR crosslinking.

View Article: PubMed Central - PubMed

Affiliation: Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne Medical Center, Köln, Germany.

ABSTRACT
Zwitterionic capsular polysaccharides (ZPS) of commensal bacteria are characterized by having both positive and negative charged substituents on each repeating unit of a highly repetitive structure that has an alpha-helix configuration. In this paper we look at the immune response of CD8(+) T cells to ZPSs. Intraperitoneal application of the ZPS Sp1 from Streptococcus pneumoniae serotype 1 induces CD8(+)CD28(-) T cells in the spleen and peritoneal cavity of WT mice. However, chemically modified Sp1 (mSp1) without the positive charge and resembling common negatively charged polysaccharides fails to induce CD8(+)CD28(-) T lymphocytes. The Sp1-induced CD8(+)CD28(-) T lymphocytes are CD122(low)CTLA-4(+)CD39(+). They synthesize IL-10 and TGF-beta. The Sp1-induced CD8(+)CD28(-) T cells exhibit immunosuppressive properties on CD4(+) T cells in vivo and in vitro. Experimental approaches to elucidate the mechanism of CD8(+) T cell activation by Sp1 demonstrate in a dimeric MHC class I-Ig model that Sp1 induces CD8(+) T cell activation by enhancing crosslinking of TCR. The expansion of CD8(+)CD28(-) T cells is independent, of direct antigen-presenting cell/T cell contact and, to the specificity of the T cell receptor (TCR). In CD8(+)CD28(-) T cells, Sp1 enhances Zap-70 phosphorylation and increasingly involves NF-kappaB which ultimately results in protection versus apoptosis and cell death and promotes survival and accumulation of the CD8(+)CD28(-) population. This is the first description of a naturally occurring bacterial antigen that is able to induce suppressive CD8(+)CD28(-) T lymphocytes in vivo and in vitro. The underlying mechanism of CD8(+) T cell activation appears to rely on enhanced TCR crosslinking. The data provides evidence that ZPS of commensal bacteria play an important role in peripheral tolerance mechanisms and the maintenance of the homeostasis of the immune system.

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Sp1 induces TCR-mediated activation in CD8+CD28− T lymphocytes.A. Sp1 induces phosphorylation of Zap-70 kinase and total Zap-70 kinase in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 4 h. Western blotting was performed with a phospho-Zap-70, Zap-70 kinase-, and a β-actin-specific antibody as a control. A representative blot out of three experiments is shown. B. Sp1 induces NF-κB activity in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 2 h. The nuclear extract of treated cells from 4 mice was analyzed by ELISA for NF-kB activity. As a positive control, the nuclear extract from Jurkat cells and as a negative control complete lysis buffer was used. The experiment was repeated three times in an independent manner. Columns indicate the mean NF-kB activity, bars indicate the standard deviation. **p<0.001,*p = 0.01.
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ppat-1000596-g005: Sp1 induces TCR-mediated activation in CD8+CD28− T lymphocytes.A. Sp1 induces phosphorylation of Zap-70 kinase and total Zap-70 kinase in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 4 h. Western blotting was performed with a phospho-Zap-70, Zap-70 kinase-, and a β-actin-specific antibody as a control. A representative blot out of three experiments is shown. B. Sp1 induces NF-κB activity in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 2 h. The nuclear extract of treated cells from 4 mice was analyzed by ELISA for NF-kB activity. As a positive control, the nuclear extract from Jurkat cells and as a negative control complete lysis buffer was used. The experiment was repeated three times in an independent manner. Columns indicate the mean NF-kB activity, bars indicate the standard deviation. **p<0.001,*p = 0.01.

Mentions: Proliferation of T cells involves the engagement of TCR by an antigen. We investigated whether CD8+CD28− T lymphocyte activation by Sp1 involves the TCR signaling cascade, resulting in T cell activation and proliferation. Following TCR engagement by an antigen, Zap-70 is rapidly phosphorylated which in turn results in enhanced Zap-70 kinase activity and downstream signaling events ultimately leading to NF-κB activation. We therefore incubated CD8+, CD8+CD28−, and CD8+CD28+ T cells in the presence of Sp1, mSp1 or medium alone and analyzed Zap-70 phosphorylation by western blotting. As shown in Fig. 5A, in contrast to medium alone or incubation with mSp1, treatment with Sp1 results in increased phosphorylation of Zap-70 in CD8+ T cells. Analysis of the CD28− and CD28+ subpopulations revealed that CD8+CD28− T lymphocytes are significantly more activated by Sp1 than CD8+CD28+ T lymphocytes. We next investigated NF-κB translocation activation. In correlation with the Zap-70 phosphorylation, Sp1 leads to significant NF-κB activation in CD8+ and CD8+CD28− T lymphocytes, but not in CD8+CD28+ T cells (Fig. 5B). It is important to note that CD8+ T cells treated with mSp1 and PBS as controls were not activated.


Streptococcus pneumoniae serotype 1 capsular polysaccharide induces CD8CD28 regulatory T lymphocytes by TCR crosslinking.

Mertens J, Fabri M, Zingarelli A, Kubacki T, Meemboor S, Groneck L, Seeger J, Bessler M, Hafke H, Odenthal M, Bieler JG, Kalka C, Schneck JP, Kashkar H, Kalka-Moll WM - PLoS Pathog. (2009)

Sp1 induces TCR-mediated activation in CD8+CD28− T lymphocytes.A. Sp1 induces phosphorylation of Zap-70 kinase and total Zap-70 kinase in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 4 h. Western blotting was performed with a phospho-Zap-70, Zap-70 kinase-, and a β-actin-specific antibody as a control. A representative blot out of three experiments is shown. B. Sp1 induces NF-κB activity in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 2 h. The nuclear extract of treated cells from 4 mice was analyzed by ELISA for NF-kB activity. As a positive control, the nuclear extract from Jurkat cells and as a negative control complete lysis buffer was used. The experiment was repeated three times in an independent manner. Columns indicate the mean NF-kB activity, bars indicate the standard deviation. **p<0.001,*p = 0.01.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2742891&req=5

ppat-1000596-g005: Sp1 induces TCR-mediated activation in CD8+CD28− T lymphocytes.A. Sp1 induces phosphorylation of Zap-70 kinase and total Zap-70 kinase in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 4 h. Western blotting was performed with a phospho-Zap-70, Zap-70 kinase-, and a β-actin-specific antibody as a control. A representative blot out of three experiments is shown. B. Sp1 induces NF-κB activity in CD8+CD28− T lymphocytes. CD8+, CD8+CD28−, and CD8+CD28+ were incubated in the presence of Sp1, mSp1 (100 µg/ml, respectively), or in medium alone for 2 h. The nuclear extract of treated cells from 4 mice was analyzed by ELISA for NF-kB activity. As a positive control, the nuclear extract from Jurkat cells and as a negative control complete lysis buffer was used. The experiment was repeated three times in an independent manner. Columns indicate the mean NF-kB activity, bars indicate the standard deviation. **p<0.001,*p = 0.01.
Mentions: Proliferation of T cells involves the engagement of TCR by an antigen. We investigated whether CD8+CD28− T lymphocyte activation by Sp1 involves the TCR signaling cascade, resulting in T cell activation and proliferation. Following TCR engagement by an antigen, Zap-70 is rapidly phosphorylated which in turn results in enhanced Zap-70 kinase activity and downstream signaling events ultimately leading to NF-κB activation. We therefore incubated CD8+, CD8+CD28−, and CD8+CD28+ T cells in the presence of Sp1, mSp1 or medium alone and analyzed Zap-70 phosphorylation by western blotting. As shown in Fig. 5A, in contrast to medium alone or incubation with mSp1, treatment with Sp1 results in increased phosphorylation of Zap-70 in CD8+ T cells. Analysis of the CD28− and CD28+ subpopulations revealed that CD8+CD28− T lymphocytes are significantly more activated by Sp1 than CD8+CD28+ T lymphocytes. We next investigated NF-κB translocation activation. In correlation with the Zap-70 phosphorylation, Sp1 leads to significant NF-κB activation in CD8+ and CD8+CD28− T lymphocytes, but not in CD8+CD28+ T cells (Fig. 5B). It is important to note that CD8+ T cells treated with mSp1 and PBS as controls were not activated.

Bottom Line: The expansion of CD8(+)CD28(-) T cells is independent, of direct antigen-presenting cell/T cell contact and, to the specificity of the T cell receptor (TCR).In CD8(+)CD28(-) T cells, Sp1 enhances Zap-70 phosphorylation and increasingly involves NF-kappaB which ultimately results in protection versus apoptosis and cell death and promotes survival and accumulation of the CD8(+)CD28(-) population.The underlying mechanism of CD8(+) T cell activation appears to rely on enhanced TCR crosslinking.

View Article: PubMed Central - PubMed

Affiliation: Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne Medical Center, Köln, Germany.

ABSTRACT
Zwitterionic capsular polysaccharides (ZPS) of commensal bacteria are characterized by having both positive and negative charged substituents on each repeating unit of a highly repetitive structure that has an alpha-helix configuration. In this paper we look at the immune response of CD8(+) T cells to ZPSs. Intraperitoneal application of the ZPS Sp1 from Streptococcus pneumoniae serotype 1 induces CD8(+)CD28(-) T cells in the spleen and peritoneal cavity of WT mice. However, chemically modified Sp1 (mSp1) without the positive charge and resembling common negatively charged polysaccharides fails to induce CD8(+)CD28(-) T lymphocytes. The Sp1-induced CD8(+)CD28(-) T lymphocytes are CD122(low)CTLA-4(+)CD39(+). They synthesize IL-10 and TGF-beta. The Sp1-induced CD8(+)CD28(-) T cells exhibit immunosuppressive properties on CD4(+) T cells in vivo and in vitro. Experimental approaches to elucidate the mechanism of CD8(+) T cell activation by Sp1 demonstrate in a dimeric MHC class I-Ig model that Sp1 induces CD8(+) T cell activation by enhancing crosslinking of TCR. The expansion of CD8(+)CD28(-) T cells is independent, of direct antigen-presenting cell/T cell contact and, to the specificity of the T cell receptor (TCR). In CD8(+)CD28(-) T cells, Sp1 enhances Zap-70 phosphorylation and increasingly involves NF-kappaB which ultimately results in protection versus apoptosis and cell death and promotes survival and accumulation of the CD8(+)CD28(-) population. This is the first description of a naturally occurring bacterial antigen that is able to induce suppressive CD8(+)CD28(-) T lymphocytes in vivo and in vitro. The underlying mechanism of CD8(+) T cell activation appears to rely on enhanced TCR crosslinking. The data provides evidence that ZPS of commensal bacteria play an important role in peripheral tolerance mechanisms and the maintenance of the homeostasis of the immune system.

Show MeSH
Related in: MedlinePlus