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Aging Impairs the Ability of Conventional Dendritic Cells to Cross-Prime CD8+ T Cells upon Stimulation with a TLR7 Ligand.

Zacca ER, Crespo MI, Acland RP, Roselli E, Núñez NG, Maccioni M, Maletto BA, Pistoresi-Palencia MC, Morón G - PLoS ONE (2015)

Bottom Line: Dendritic cells (DCs) are antigen-presenting cells that play a key role in both adaptive and innate immunity, but how aging affects DCs and their influence on immunity has not been thoroughly established.Using polyU, a synthetic ssRNA analog, as TLR7 ligand and OVA as an antigen (Ag) model, we found that cDCs from old mice have a poor ability to stimulate a CD8+ T cell-mediated cytotoxic response. cDCs from old mice exhibit alterations in Ag-processing machinery and TLR7 activation.Taken together, our results suggest that immunosenescence impacts cDC function, affecting the activation of naïve CD8+ T cells and the generation of effector cytotoxic T cells.

View Article: PubMed Central - PubMed

Affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.

ABSTRACT
The aging process is accompanied by altered immune system functioning and an increased risk of infection. Dendritic cells (DCs) are antigen-presenting cells that play a key role in both adaptive and innate immunity, but how aging affects DCs and their influence on immunity has not been thoroughly established. Here we examined the function of conventional DCs (cDCs) in old mice after TLR7 stimulation, focusing on their ability to cross-prime CD8+ T cells. Using polyU, a synthetic ssRNA analog, as TLR7 ligand and OVA as an antigen (Ag) model, we found that cDCs from old mice have a poor ability to stimulate a CD8+ T cell-mediated cytotoxic response. cDCs from old mice exhibit alterations in Ag-processing machinery and TLR7 activation. Remarkably, CD8α+ cDCs from old mice have an impaired ability to activate naïve CD8+ T cells and, moreover, a lower capacity to mature and to process exogenous Ag. Taken together, our results suggest that immunosenescence impacts cDC function, affecting the activation of naïve CD8+ T cells and the generation of effector cytotoxic T cells.

No MeSH data available.


Related in: MedlinePlus

Ag presentation on MHC I molecules is affected in cDCs from old mice but Ag uptake is preserved.(A) In vitro Ag presentation assay. cDCs purified from the spleen of young and old mice were incubated with several OVA concentrations forming IC-OVA for 4 hours and then they were washed and incubated with B3Z cells overnight. B3Z stimulation, monitored by colorimetric bulk determination of β-galactosidase, is expressed as optical density (OD) at λ = 595. (B, C) In vitro Ag capture assay. (B) Spleen cells from young and old mice were recovered and incubated for 90 minutes with soluble OVA-FITC (upper) or IC-OVA-FITC (lower). Then, spleen cells were labeled with anti-CD11c Ab. Results are expressed as mean ± SEM of MFI in FITC channel. (C) CD8α+ cDCs purified from young and old mice were incubated for 90 minutes with soluble OVA-AF647. Results are expressed as mean ± SEM of MFI in AF647 channel. Results are representative of 3 independent experiments (3–4 mice/age group/experiment).
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pone.0140672.g003: Ag presentation on MHC I molecules is affected in cDCs from old mice but Ag uptake is preserved.(A) In vitro Ag presentation assay. cDCs purified from the spleen of young and old mice were incubated with several OVA concentrations forming IC-OVA for 4 hours and then they were washed and incubated with B3Z cells overnight. B3Z stimulation, monitored by colorimetric bulk determination of β-galactosidase, is expressed as optical density (OD) at λ = 595. (B, C) In vitro Ag capture assay. (B) Spleen cells from young and old mice were recovered and incubated for 90 minutes with soluble OVA-FITC (upper) or IC-OVA-FITC (lower). Then, spleen cells were labeled with anti-CD11c Ab. Results are expressed as mean ± SEM of MFI in FITC channel. (C) CD8α+ cDCs purified from young and old mice were incubated for 90 minutes with soluble OVA-AF647. Results are expressed as mean ± SEM of MFI in AF647 channel. Results are representative of 3 independent experiments (3–4 mice/age group/experiment).

Mentions: The initiation of an immunogenic CD8+ T cell response to an Ag that is not synthesized by the APC is known as cross-priming, and requires the ability of DCs to load peptides derived from exogenous Ags onto MHC class I molecules [29]. It is possible to determine the ability of DCs to present specific OVA257-264-Kb complexes on their cell surface by using an MHC I Ag presentation assay with the B3Z CD8+ T cell hybridoma, specific for the H2-Kb–restricted OVA257-264 epitope. We performed an in vitro assay to assess the intrinsic ability of DCs (without any other influence than DCs themselves) to achieve MHC I Ag presentation. cDCs from young and old mice were incubated with different concentrations of OVA forming immune complexes (IC-OVA) and the presence of OVA257-264-Kb complexes on cDCs was monitored by the activation of B3Z cells (see Materials and Methods). As shown in Fig 3A, cDCs from young mice exhibited a greater ability to activate B3Z cells than cDCs from old mice. This indicates that aging decreased the ability of cDCs to cross-present the OVA257-264 peptide in MHC I molecules.


Aging Impairs the Ability of Conventional Dendritic Cells to Cross-Prime CD8+ T Cells upon Stimulation with a TLR7 Ligand.

Zacca ER, Crespo MI, Acland RP, Roselli E, Núñez NG, Maccioni M, Maletto BA, Pistoresi-Palencia MC, Morón G - PLoS ONE (2015)

Ag presentation on MHC I molecules is affected in cDCs from old mice but Ag uptake is preserved.(A) In vitro Ag presentation assay. cDCs purified from the spleen of young and old mice were incubated with several OVA concentrations forming IC-OVA for 4 hours and then they were washed and incubated with B3Z cells overnight. B3Z stimulation, monitored by colorimetric bulk determination of β-galactosidase, is expressed as optical density (OD) at λ = 595. (B, C) In vitro Ag capture assay. (B) Spleen cells from young and old mice were recovered and incubated for 90 minutes with soluble OVA-FITC (upper) or IC-OVA-FITC (lower). Then, spleen cells were labeled with anti-CD11c Ab. Results are expressed as mean ± SEM of MFI in FITC channel. (C) CD8α+ cDCs purified from young and old mice were incubated for 90 minutes with soluble OVA-AF647. Results are expressed as mean ± SEM of MFI in AF647 channel. Results are representative of 3 independent experiments (3–4 mice/age group/experiment).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608578&req=5

pone.0140672.g003: Ag presentation on MHC I molecules is affected in cDCs from old mice but Ag uptake is preserved.(A) In vitro Ag presentation assay. cDCs purified from the spleen of young and old mice were incubated with several OVA concentrations forming IC-OVA for 4 hours and then they were washed and incubated with B3Z cells overnight. B3Z stimulation, monitored by colorimetric bulk determination of β-galactosidase, is expressed as optical density (OD) at λ = 595. (B, C) In vitro Ag capture assay. (B) Spleen cells from young and old mice were recovered and incubated for 90 minutes with soluble OVA-FITC (upper) or IC-OVA-FITC (lower). Then, spleen cells were labeled with anti-CD11c Ab. Results are expressed as mean ± SEM of MFI in FITC channel. (C) CD8α+ cDCs purified from young and old mice were incubated for 90 minutes with soluble OVA-AF647. Results are expressed as mean ± SEM of MFI in AF647 channel. Results are representative of 3 independent experiments (3–4 mice/age group/experiment).
Mentions: The initiation of an immunogenic CD8+ T cell response to an Ag that is not synthesized by the APC is known as cross-priming, and requires the ability of DCs to load peptides derived from exogenous Ags onto MHC class I molecules [29]. It is possible to determine the ability of DCs to present specific OVA257-264-Kb complexes on their cell surface by using an MHC I Ag presentation assay with the B3Z CD8+ T cell hybridoma, specific for the H2-Kb–restricted OVA257-264 epitope. We performed an in vitro assay to assess the intrinsic ability of DCs (without any other influence than DCs themselves) to achieve MHC I Ag presentation. cDCs from young and old mice were incubated with different concentrations of OVA forming immune complexes (IC-OVA) and the presence of OVA257-264-Kb complexes on cDCs was monitored by the activation of B3Z cells (see Materials and Methods). As shown in Fig 3A, cDCs from young mice exhibited a greater ability to activate B3Z cells than cDCs from old mice. This indicates that aging decreased the ability of cDCs to cross-present the OVA257-264 peptide in MHC I molecules.

Bottom Line: Dendritic cells (DCs) are antigen-presenting cells that play a key role in both adaptive and innate immunity, but how aging affects DCs and their influence on immunity has not been thoroughly established.Using polyU, a synthetic ssRNA analog, as TLR7 ligand and OVA as an antigen (Ag) model, we found that cDCs from old mice have a poor ability to stimulate a CD8+ T cell-mediated cytotoxic response. cDCs from old mice exhibit alterations in Ag-processing machinery and TLR7 activation.Taken together, our results suggest that immunosenescence impacts cDC function, affecting the activation of naïve CD8+ T cells and the generation of effector cytotoxic T cells.

View Article: PubMed Central - PubMed

Affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.

ABSTRACT
The aging process is accompanied by altered immune system functioning and an increased risk of infection. Dendritic cells (DCs) are antigen-presenting cells that play a key role in both adaptive and innate immunity, but how aging affects DCs and their influence on immunity has not been thoroughly established. Here we examined the function of conventional DCs (cDCs) in old mice after TLR7 stimulation, focusing on their ability to cross-prime CD8+ T cells. Using polyU, a synthetic ssRNA analog, as TLR7 ligand and OVA as an antigen (Ag) model, we found that cDCs from old mice have a poor ability to stimulate a CD8+ T cell-mediated cytotoxic response. cDCs from old mice exhibit alterations in Ag-processing machinery and TLR7 activation. Remarkably, CD8α+ cDCs from old mice have an impaired ability to activate naïve CD8+ T cells and, moreover, a lower capacity to mature and to process exogenous Ag. Taken together, our results suggest that immunosenescence impacts cDC function, affecting the activation of naïve CD8+ T cells and the generation of effector cytotoxic T cells.

No MeSH data available.


Related in: MedlinePlus