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Dyslipidemia inhibits Toll-like receptor-induced activation of CD8alpha-negative dendritic cells and protective Th1 type immunity.

Shamshiev AT, Ampenberger F, Ernst B, Rohrer L, Marsland BJ, Kopf M - J. Exp. Med. (2007)

Bottom Line: Decreased DC activation profoundly influenced T helper (Th) cell responses, leading to impaired Th1 and enhanced Th2 responses.We found that oxidized low-density lipoprotein (oxLDL) was the key active component responsible for this effect, as it could directly uncouple TLR-mediated signaling on CD8alpha(-) myeloid DCs and inhibit NF-kappaB nuclear translocation.These results show that a dyslipidemic microenvironment can directly interfere with DC responses to pathogen-derived signals and skew the development of T cell-mediated immunity.

View Article: PubMed Central - PubMed

Affiliation: Molecular Biomedicine, Institute of Integrative Biology, Swiss Federal Institute of Technology Zürich, 8952 Zürich, Switzerland.

ABSTRACT
Environmental factors, including diet, play a central role in influencing the balance of normal immune homeostasis; however, many of the cellular mechanisms maintaining this balance remain to be elucidated. Using mouse models of genetic and high-fat/cholesterol diet-induced dyslipidemia, we examined the influence of dyslipidemia on T cell and dendritic cell (DC) responses in vivo and in vitro. We show that dyslipidemia inhibited Toll-like receptor (TLR)-induced production of proinflammatory cytokines, including interleukin (IL)-12, IL-6, and tumor necrosis factor-alpha, as well as up-regulation of costimulatory molecules by CD8alpha(-) DCs, but not by CD8alpha(+) DCs, in vivo. Decreased DC activation profoundly influenced T helper (Th) cell responses, leading to impaired Th1 and enhanced Th2 responses. As a consequence of this immune modulation, host resistance to Leishmania major was compromised. We found that oxidized low-density lipoprotein (oxLDL) was the key active component responsible for this effect, as it could directly uncouple TLR-mediated signaling on CD8alpha(-) myeloid DCs and inhibit NF-kappaB nuclear translocation. These results show that a dyslipidemic microenvironment can directly interfere with DC responses to pathogen-derived signals and skew the development of T cell-mediated immunity.

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oxLDL inhibits CpG-induced IL-12p40 production and NF-κB nuclear translocation in CD8α− DCs, and promotes Th2 cell differentiation. (A) C57BL/6 splenic DCs were incubated with 40 μg/ml nLDL or 40 μg/ml oxLDL for 1 h at 37°C. After washing, DCs were activated with 100 nM CpG or 5 μg/ml R837 for 6 h, followed by surface staining for CD11c and CD8α, and intracellular staining for IL-12p40. Gated on CD11c+ cells. The numbers indicate the percentage of cells in each quadrant. (B) C57BL/6 mice (n = 3) were injected i.v. with 2 mg/dose of either nLDL or oxLDL. After 3 h, splenic DCs were ex vivo stimulated with CpG and stained as described for A. (C) BMDCs were cultured on coverslips and incubated with 60 μg/ml nLDL or 60 μg/ml oxLDL for 1 h, and then stimulated with 300 nM CpG for 30 min at 37°C. Cells were permeabilized and immunostained with anti–NF-κB p65 and Alexa Fluor goat anti–rabbit IgG (green, top); nuclei were stained with DAPI (blue, bottom). (D) C57BL/6 splenic DCs were exposed to10 μg/ml nLDL or 10 μg/ml oxLDL for 1 h and co-cultured with naive GP61-80-specific CD4+ T cells in the presence of 100 nM GP61-80 peptide. At day 4, T cells were restimulated with PMA/ionomycin and stained for intracellular IL-4 and IFN-γ. Gated on CD4+ T cells. The numbers indicate the percentage of cells in each quadrant.
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fig8: oxLDL inhibits CpG-induced IL-12p40 production and NF-κB nuclear translocation in CD8α− DCs, and promotes Th2 cell differentiation. (A) C57BL/6 splenic DCs were incubated with 40 μg/ml nLDL or 40 μg/ml oxLDL for 1 h at 37°C. After washing, DCs were activated with 100 nM CpG or 5 μg/ml R837 for 6 h, followed by surface staining for CD11c and CD8α, and intracellular staining for IL-12p40. Gated on CD11c+ cells. The numbers indicate the percentage of cells in each quadrant. (B) C57BL/6 mice (n = 3) were injected i.v. with 2 mg/dose of either nLDL or oxLDL. After 3 h, splenic DCs were ex vivo stimulated with CpG and stained as described for A. (C) BMDCs were cultured on coverslips and incubated with 60 μg/ml nLDL or 60 μg/ml oxLDL for 1 h, and then stimulated with 300 nM CpG for 30 min at 37°C. Cells were permeabilized and immunostained with anti–NF-κB p65 and Alexa Fluor goat anti–rabbit IgG (green, top); nuclei were stained with DAPI (blue, bottom). (D) C57BL/6 splenic DCs were exposed to10 μg/ml nLDL or 10 μg/ml oxLDL for 1 h and co-cultured with naive GP61-80-specific CD4+ T cells in the presence of 100 nM GP61-80 peptide. At day 4, T cells were restimulated with PMA/ionomycin and stained for intracellular IL-4 and IFN-γ. Gated on CD4+ T cells. The numbers indicate the percentage of cells in each quadrant.

Mentions: To test whether oxLDL was capable of regulating DC function directly, we pulsed splenic DCs isolated from chow diet–fed C57BL/6 mice with human oxLDL or native LDL (nLDL) before stimulation with CpG or imiquimod (R837). Intracellular cytokine staining revealed that oxLDL treatment inhibited TLR-induced IL-12p40 production in the CD8α− DC subset without affecting the CD8α+ DC subset (Fig. 8 A). Consistent with in vitro findings, injection of oxLDL into C57BL/6 mice inhibited IL-12 production by CD8α−, but not CD8α+ DCs upon ex vivo CpG stimulation (Fig. 8 B).


Dyslipidemia inhibits Toll-like receptor-induced activation of CD8alpha-negative dendritic cells and protective Th1 type immunity.

Shamshiev AT, Ampenberger F, Ernst B, Rohrer L, Marsland BJ, Kopf M - J. Exp. Med. (2007)

oxLDL inhibits CpG-induced IL-12p40 production and NF-κB nuclear translocation in CD8α− DCs, and promotes Th2 cell differentiation. (A) C57BL/6 splenic DCs were incubated with 40 μg/ml nLDL or 40 μg/ml oxLDL for 1 h at 37°C. After washing, DCs were activated with 100 nM CpG or 5 μg/ml R837 for 6 h, followed by surface staining for CD11c and CD8α, and intracellular staining for IL-12p40. Gated on CD11c+ cells. The numbers indicate the percentage of cells in each quadrant. (B) C57BL/6 mice (n = 3) were injected i.v. with 2 mg/dose of either nLDL or oxLDL. After 3 h, splenic DCs were ex vivo stimulated with CpG and stained as described for A. (C) BMDCs were cultured on coverslips and incubated with 60 μg/ml nLDL or 60 μg/ml oxLDL for 1 h, and then stimulated with 300 nM CpG for 30 min at 37°C. Cells were permeabilized and immunostained with anti–NF-κB p65 and Alexa Fluor goat anti–rabbit IgG (green, top); nuclei were stained with DAPI (blue, bottom). (D) C57BL/6 splenic DCs were exposed to10 μg/ml nLDL or 10 μg/ml oxLDL for 1 h and co-cultured with naive GP61-80-specific CD4+ T cells in the presence of 100 nM GP61-80 peptide. At day 4, T cells were restimulated with PMA/ionomycin and stained for intracellular IL-4 and IFN-γ. Gated on CD4+ T cells. The numbers indicate the percentage of cells in each quadrant.
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Related In: Results  -  Collection

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fig8: oxLDL inhibits CpG-induced IL-12p40 production and NF-κB nuclear translocation in CD8α− DCs, and promotes Th2 cell differentiation. (A) C57BL/6 splenic DCs were incubated with 40 μg/ml nLDL or 40 μg/ml oxLDL for 1 h at 37°C. After washing, DCs were activated with 100 nM CpG or 5 μg/ml R837 for 6 h, followed by surface staining for CD11c and CD8α, and intracellular staining for IL-12p40. Gated on CD11c+ cells. The numbers indicate the percentage of cells in each quadrant. (B) C57BL/6 mice (n = 3) were injected i.v. with 2 mg/dose of either nLDL or oxLDL. After 3 h, splenic DCs were ex vivo stimulated with CpG and stained as described for A. (C) BMDCs were cultured on coverslips and incubated with 60 μg/ml nLDL or 60 μg/ml oxLDL for 1 h, and then stimulated with 300 nM CpG for 30 min at 37°C. Cells were permeabilized and immunostained with anti–NF-κB p65 and Alexa Fluor goat anti–rabbit IgG (green, top); nuclei were stained with DAPI (blue, bottom). (D) C57BL/6 splenic DCs were exposed to10 μg/ml nLDL or 10 μg/ml oxLDL for 1 h and co-cultured with naive GP61-80-specific CD4+ T cells in the presence of 100 nM GP61-80 peptide. At day 4, T cells were restimulated with PMA/ionomycin and stained for intracellular IL-4 and IFN-γ. Gated on CD4+ T cells. The numbers indicate the percentage of cells in each quadrant.
Mentions: To test whether oxLDL was capable of regulating DC function directly, we pulsed splenic DCs isolated from chow diet–fed C57BL/6 mice with human oxLDL or native LDL (nLDL) before stimulation with CpG or imiquimod (R837). Intracellular cytokine staining revealed that oxLDL treatment inhibited TLR-induced IL-12p40 production in the CD8α− DC subset without affecting the CD8α+ DC subset (Fig. 8 A). Consistent with in vitro findings, injection of oxLDL into C57BL/6 mice inhibited IL-12 production by CD8α−, but not CD8α+ DCs upon ex vivo CpG stimulation (Fig. 8 B).

Bottom Line: Decreased DC activation profoundly influenced T helper (Th) cell responses, leading to impaired Th1 and enhanced Th2 responses.We found that oxidized low-density lipoprotein (oxLDL) was the key active component responsible for this effect, as it could directly uncouple TLR-mediated signaling on CD8alpha(-) myeloid DCs and inhibit NF-kappaB nuclear translocation.These results show that a dyslipidemic microenvironment can directly interfere with DC responses to pathogen-derived signals and skew the development of T cell-mediated immunity.

View Article: PubMed Central - PubMed

Affiliation: Molecular Biomedicine, Institute of Integrative Biology, Swiss Federal Institute of Technology Zürich, 8952 Zürich, Switzerland.

ABSTRACT
Environmental factors, including diet, play a central role in influencing the balance of normal immune homeostasis; however, many of the cellular mechanisms maintaining this balance remain to be elucidated. Using mouse models of genetic and high-fat/cholesterol diet-induced dyslipidemia, we examined the influence of dyslipidemia on T cell and dendritic cell (DC) responses in vivo and in vitro. We show that dyslipidemia inhibited Toll-like receptor (TLR)-induced production of proinflammatory cytokines, including interleukin (IL)-12, IL-6, and tumor necrosis factor-alpha, as well as up-regulation of costimulatory molecules by CD8alpha(-) DCs, but not by CD8alpha(+) DCs, in vivo. Decreased DC activation profoundly influenced T helper (Th) cell responses, leading to impaired Th1 and enhanced Th2 responses. As a consequence of this immune modulation, host resistance to Leishmania major was compromised. We found that oxidized low-density lipoprotein (oxLDL) was the key active component responsible for this effect, as it could directly uncouple TLR-mediated signaling on CD8alpha(-) myeloid DCs and inhibit NF-kappaB nuclear translocation. These results show that a dyslipidemic microenvironment can directly interfere with DC responses to pathogen-derived signals and skew the development of T cell-mediated immunity.

Show MeSH
Related in: MedlinePlus