Limits...
Ceramide inhibits antigen uptake and presentation by dendritic cells.

Sallusto F, Nicolò C, De Maria R, Corinti S, Testi R - J. Exp. Med. (1996)

Bottom Line: Dendritic cells down-modulate their capacity to take up soluble antigens in response to exogenously added or endogenously produced ceramides.This is followed by an impairment in presenting soluble antigens to specific T cell clones, while cell viability and the capacity to stimulate allogeneic responses or to present immunogenic peptides is fully preserved.Thus, ceramide-mediated pathways initiated by different cytokines can actively modulate professional antigen-presenting cell function and antigen-specific immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Istituto Superiore di Sanità, Rome, Italy.

ABSTRACT
Ceramides are intramembrane diffusible mediators involved in transducing signals originated from a variety of cell surface receptors. Different adaptive and differentiative cellular responses, including apoptotic cell death, use ceramide-mediated pathways as an essential part of the program. Here, we show that human dendritic cells respond to CD40 ligand, as well as to tumor necrosis factor-alpha and IL-1 beta, with intracellular ceramide accumulation, as they are induced to differentiate. Dendritic cells down-modulate their capacity to take up soluble antigens in response to exogenously added or endogenously produced ceramides. This is followed by an impairment in presenting soluble antigens to specific T cell clones, while cell viability and the capacity to stimulate allogeneic responses or to present immunogenic peptides is fully preserved. Thus, ceramide-mediated pathways initiated by different cytokines can actively modulate professional antigen-presenting cell function and antigen-specific immune responses.

Show MeSH

Related in: MedlinePlus

C2-ceramide inhibits both fluid phase and mannose receptor  mediated endocytosis by DCs. (A, C, E) 2 × 105 DCs were incubated  with different concentrations of C2-ceramide (open circles), C2-dihydroceramide (closed circles), or diacylglycerol (closed triangles) for 10 min on ice,  then transferred at 37°C and LY (1 mg/ml) (A), FITC–DX (1 mg/ml)  (C), or HRP (0.1 μg/ml) (E) were added for 30 min. Results are expressed as percent of maximum uptake. The background (cells pulsed at  0°C) was less than 1% of the uptake at 37°C in all the experiments. (B, D,  F) 2 × 105 DCs were pretreated with 80 μM C2-ceramide (open circles) or  medium (closed squares) for 10 min on ice, then transferred at 37°C and LY  (B), FITC–DX (D) or HRP (F) accumulation was measured at different  times. Results are expressed as mean fluorescence intensity (B, D) or as  amount of cell-associated HRP (F). Comparable results were obtained using five different DC preparations. The vehicle did not affect endocytosis  (data not shown).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2196395&req=5

Figure 2: C2-ceramide inhibits both fluid phase and mannose receptor mediated endocytosis by DCs. (A, C, E) 2 × 105 DCs were incubated with different concentrations of C2-ceramide (open circles), C2-dihydroceramide (closed circles), or diacylglycerol (closed triangles) for 10 min on ice, then transferred at 37°C and LY (1 mg/ml) (A), FITC–DX (1 mg/ml) (C), or HRP (0.1 μg/ml) (E) were added for 30 min. Results are expressed as percent of maximum uptake. The background (cells pulsed at 0°C) was less than 1% of the uptake at 37°C in all the experiments. (B, D, F) 2 × 105 DCs were pretreated with 80 μM C2-ceramide (open circles) or medium (closed squares) for 10 min on ice, then transferred at 37°C and LY (B), FITC–DX (D) or HRP (F) accumulation was measured at different times. Results are expressed as mean fluorescence intensity (B, D) or as amount of cell-associated HRP (F). Comparable results were obtained using five different DC preparations. The vehicle did not affect endocytosis (data not shown).

Mentions: To test this hypothesis directly, we investigated whether exposure to exogenous cell-permeant C2-ceramide could down-modulate DC antigen uptake ability. DCs capture antigen either via macropinocytosis, a cytoskeleton-dependent type of fluid phase endocytosis initiated by membrane ruffling and formation of large vesicles, or receptor-mediated endocytosis through Fcγ and mannose receptors (5). As shown in Fig. 2, C2-ceramide could inhibit the uptake of three different classical endocytosis markers and their time-dependent accumulation into DCs. Both macropinocytosis, as assessed by LY and FITC-DX, and receptormediated endocytosis, as assessed by limiting amounts of HRP, were significantly affected. Comparable results were also obtained using C6-ceramide, a longer acyl chain ceramide analogue (data not shown). By contrast, C2-dihydroceramide, a structural analogue of C2-ceramide that lacks a double bond at the 4–5 position in the sphingoid base, was ineffective. Similarly, exposure to other diffusible signaltransducing lipid mediators such as diacylglycerol, did not affect macromolecule uptake ability of DCs (Fig. 2, A, C, E).


Ceramide inhibits antigen uptake and presentation by dendritic cells.

Sallusto F, Nicolò C, De Maria R, Corinti S, Testi R - J. Exp. Med. (1996)

C2-ceramide inhibits both fluid phase and mannose receptor  mediated endocytosis by DCs. (A, C, E) 2 × 105 DCs were incubated  with different concentrations of C2-ceramide (open circles), C2-dihydroceramide (closed circles), or diacylglycerol (closed triangles) for 10 min on ice,  then transferred at 37°C and LY (1 mg/ml) (A), FITC–DX (1 mg/ml)  (C), or HRP (0.1 μg/ml) (E) were added for 30 min. Results are expressed as percent of maximum uptake. The background (cells pulsed at  0°C) was less than 1% of the uptake at 37°C in all the experiments. (B, D,  F) 2 × 105 DCs were pretreated with 80 μM C2-ceramide (open circles) or  medium (closed squares) for 10 min on ice, then transferred at 37°C and LY  (B), FITC–DX (D) or HRP (F) accumulation was measured at different  times. Results are expressed as mean fluorescence intensity (B, D) or as  amount of cell-associated HRP (F). Comparable results were obtained using five different DC preparations. The vehicle did not affect endocytosis  (data not shown).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196395&req=5

Figure 2: C2-ceramide inhibits both fluid phase and mannose receptor mediated endocytosis by DCs. (A, C, E) 2 × 105 DCs were incubated with different concentrations of C2-ceramide (open circles), C2-dihydroceramide (closed circles), or diacylglycerol (closed triangles) for 10 min on ice, then transferred at 37°C and LY (1 mg/ml) (A), FITC–DX (1 mg/ml) (C), or HRP (0.1 μg/ml) (E) were added for 30 min. Results are expressed as percent of maximum uptake. The background (cells pulsed at 0°C) was less than 1% of the uptake at 37°C in all the experiments. (B, D, F) 2 × 105 DCs were pretreated with 80 μM C2-ceramide (open circles) or medium (closed squares) for 10 min on ice, then transferred at 37°C and LY (B), FITC–DX (D) or HRP (F) accumulation was measured at different times. Results are expressed as mean fluorescence intensity (B, D) or as amount of cell-associated HRP (F). Comparable results were obtained using five different DC preparations. The vehicle did not affect endocytosis (data not shown).
Mentions: To test this hypothesis directly, we investigated whether exposure to exogenous cell-permeant C2-ceramide could down-modulate DC antigen uptake ability. DCs capture antigen either via macropinocytosis, a cytoskeleton-dependent type of fluid phase endocytosis initiated by membrane ruffling and formation of large vesicles, or receptor-mediated endocytosis through Fcγ and mannose receptors (5). As shown in Fig. 2, C2-ceramide could inhibit the uptake of three different classical endocytosis markers and their time-dependent accumulation into DCs. Both macropinocytosis, as assessed by LY and FITC-DX, and receptormediated endocytosis, as assessed by limiting amounts of HRP, were significantly affected. Comparable results were also obtained using C6-ceramide, a longer acyl chain ceramide analogue (data not shown). By contrast, C2-dihydroceramide, a structural analogue of C2-ceramide that lacks a double bond at the 4–5 position in the sphingoid base, was ineffective. Similarly, exposure to other diffusible signaltransducing lipid mediators such as diacylglycerol, did not affect macromolecule uptake ability of DCs (Fig. 2, A, C, E).

Bottom Line: Dendritic cells down-modulate their capacity to take up soluble antigens in response to exogenously added or endogenously produced ceramides.This is followed by an impairment in presenting soluble antigens to specific T cell clones, while cell viability and the capacity to stimulate allogeneic responses or to present immunogenic peptides is fully preserved.Thus, ceramide-mediated pathways initiated by different cytokines can actively modulate professional antigen-presenting cell function and antigen-specific immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Istituto Superiore di Sanità, Rome, Italy.

ABSTRACT
Ceramides are intramembrane diffusible mediators involved in transducing signals originated from a variety of cell surface receptors. Different adaptive and differentiative cellular responses, including apoptotic cell death, use ceramide-mediated pathways as an essential part of the program. Here, we show that human dendritic cells respond to CD40 ligand, as well as to tumor necrosis factor-alpha and IL-1 beta, with intracellular ceramide accumulation, as they are induced to differentiate. Dendritic cells down-modulate their capacity to take up soluble antigens in response to exogenously added or endogenously produced ceramides. This is followed by an impairment in presenting soluble antigens to specific T cell clones, while cell viability and the capacity to stimulate allogeneic responses or to present immunogenic peptides is fully preserved. Thus, ceramide-mediated pathways initiated by different cytokines can actively modulate professional antigen-presenting cell function and antigen-specific immune responses.

Show MeSH
Related in: MedlinePlus