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Priming of Salmonella enterica serovar typhi-specific CD8(+) T cells by suicide dendritic cell cross-presentation in humans.

Salerno-Goncalves R, Sztein MB - PLoS ONE (2009)

Bottom Line: Typhi-infected human cells and release high levels of IFN-gamma and IL-12p70, leading to the subsequent presentation of bacterial antigens and triggering the induction of memory T cells, mostly CD3(+)CD8(+)CD45RA(-)CD62L(-) effector/memory T cells.This study is the first to demonstrate the effect of S.Typhi.

View Article: PubMed Central - PubMed

Affiliation: Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA. rmezghan@medicine.umaryland.edu

ABSTRACT

Background: The emergence of antibiotic-resistant strains of Salmonella enterica serovar Typhi (S. Typhi), the etiologic agent of typhoid fever, has aggravated an already important public health problem and added new urgency to the development of more effective typhoid vaccines. To this end it is critical to better understand the induction of immunity to S. Typhi. CD8(+) T cells are likely to play an important role in host defense against S. Typhi by several effector mechanisms, including killing of infected cells and IFN-gamma secretion. However, how S. Typhi regulates the development of specific CD8(+) responses in humans remains unclear. Recent studies in mice have shown that dendritic cells (DC) can either directly (upon uptake and processing of Salmonella) or indirectly (by bystander mechanisms) elicit Salmonella-specific CD8(+) T cells.

Methodology/principal findings: We report here that upon infection with live S. Typhi, human DC produced high levels of pro-inflammatory cytokines IL-6, IL-8 and TNF-alpha, but low levels of IL-12 p70 and IFN-gamma. In contrast, DC co-cultured with S. Typhi-infected cells, through suicide cross-presentation, uptake S. Typhi-infected human cells and release high levels of IFN-gamma and IL-12p70, leading to the subsequent presentation of bacterial antigens and triggering the induction of memory T cells, mostly CD3(+)CD8(+)CD45RA(-)CD62L(-) effector/memory T cells.

Conclusions/significance: This study is the first to demonstrate the effect of S. Typhi on human DC maturation and on their ability to prime CD8(+) cells and highlights the significance of these phenomena in eliciting adaptive immunity to S. Typhi.

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Modulation of cell surface expression of CD80 and CD83 molecules during S. Typhi-induced DC maturation.Immature DC were cultured for 30 h in the absence (media) or in the presence of LPS (1 µg/ml), with live or heat-killed S. Typhi at different MOI or uninfected or S. Typhi-infected blasts at a DC∶blast ratio of 4∶1. Cells were stained with mAbs to CD3, CD14, CD19, DC-Sign, HLA-DR, CD80 and CD83 or isotype-matched control Abs and analyzed by flow cytometry. Histogram shows the levels of CD80 and CD83 expression on CD3− CD14−CD19− DC-Sign+ HLA-DR+ gated cells. Numbers correspond to the % of CD80+ CD83+ positive cells in the indicated quadrant in each histogram followed by mean fluorescence intensity (MFI) of all CD80 positive cells (in parenthesis). Panel “A” shows the results of one volunteer, CVD5000#12U. Panel “B” shows the results of three volunteers, CVD4000# 28, 63 and 65.
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pone-0005879-g001: Modulation of cell surface expression of CD80 and CD83 molecules during S. Typhi-induced DC maturation.Immature DC were cultured for 30 h in the absence (media) or in the presence of LPS (1 µg/ml), with live or heat-killed S. Typhi at different MOI or uninfected or S. Typhi-infected blasts at a DC∶blast ratio of 4∶1. Cells were stained with mAbs to CD3, CD14, CD19, DC-Sign, HLA-DR, CD80 and CD83 or isotype-matched control Abs and analyzed by flow cytometry. Histogram shows the levels of CD80 and CD83 expression on CD3− CD14−CD19− DC-Sign+ HLA-DR+ gated cells. Numbers correspond to the % of CD80+ CD83+ positive cells in the indicated quadrant in each histogram followed by mean fluorescence intensity (MFI) of all CD80 positive cells (in parenthesis). Panel “A” shows the results of one volunteer, CVD5000#12U. Panel “B” shows the results of three volunteers, CVD4000# 28, 63 and 65.

Mentions: To efficiently present antigens to naïve T cells, immature DC must be activated to mature, a process accompanied by up-regulation of MHC and costimulatory molecules [24]. To investigate whether S. Typhi drives DC maturation, we evaluated the DC surface expression of CD80 and CD83 costimulatory molecules after different stimulatory conditions. Unstimulated DC (media) were used as negative controls. We observed that DC pulsed with live S. Typhi increased their surface expression of CD80 and CD83 in a dose-dependent manner (Fig. 1A) with levels comparable to those induced following exposure to LPS, a potent DC maturation factor [25] (Fig. 1B). Increases, albeit at lower levels, were also apparent when DC were pulsed with heat-inactivated S. Typhi demonstrating that neither bacterial infection nor viability was required for the observed effects. These results are in agreement with others using S. Typhimurium in a mouse model [26]. However, the exposure of DC to S. Typhi-infected blasts induced comparable or higher levels of CD80 and CD83 expression on DC than those induced by exposure of DC to live S. Typhi or LPS (Fig. 1B). Of interest, the expression level of CD80 and CD83 molecules on DC pulsed with not-infected blasts were similar to those observed in DC cultured in media alone (Fig. 1B). In conclusion, the appearance of DC exhibiting higher levels of CD83 and CD80 molecules after incubation with S. Typhi antigens demonstrated that S. Typhi drives DC maturation in humans.


Priming of Salmonella enterica serovar typhi-specific CD8(+) T cells by suicide dendritic cell cross-presentation in humans.

Salerno-Goncalves R, Sztein MB - PLoS ONE (2009)

Modulation of cell surface expression of CD80 and CD83 molecules during S. Typhi-induced DC maturation.Immature DC were cultured for 30 h in the absence (media) or in the presence of LPS (1 µg/ml), with live or heat-killed S. Typhi at different MOI or uninfected or S. Typhi-infected blasts at a DC∶blast ratio of 4∶1. Cells were stained with mAbs to CD3, CD14, CD19, DC-Sign, HLA-DR, CD80 and CD83 or isotype-matched control Abs and analyzed by flow cytometry. Histogram shows the levels of CD80 and CD83 expression on CD3− CD14−CD19− DC-Sign+ HLA-DR+ gated cells. Numbers correspond to the % of CD80+ CD83+ positive cells in the indicated quadrant in each histogram followed by mean fluorescence intensity (MFI) of all CD80 positive cells (in parenthesis). Panel “A” shows the results of one volunteer, CVD5000#12U. Panel “B” shows the results of three volunteers, CVD4000# 28, 63 and 65.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2691582&req=5

pone-0005879-g001: Modulation of cell surface expression of CD80 and CD83 molecules during S. Typhi-induced DC maturation.Immature DC were cultured for 30 h in the absence (media) or in the presence of LPS (1 µg/ml), with live or heat-killed S. Typhi at different MOI or uninfected or S. Typhi-infected blasts at a DC∶blast ratio of 4∶1. Cells were stained with mAbs to CD3, CD14, CD19, DC-Sign, HLA-DR, CD80 and CD83 or isotype-matched control Abs and analyzed by flow cytometry. Histogram shows the levels of CD80 and CD83 expression on CD3− CD14−CD19− DC-Sign+ HLA-DR+ gated cells. Numbers correspond to the % of CD80+ CD83+ positive cells in the indicated quadrant in each histogram followed by mean fluorescence intensity (MFI) of all CD80 positive cells (in parenthesis). Panel “A” shows the results of one volunteer, CVD5000#12U. Panel “B” shows the results of three volunteers, CVD4000# 28, 63 and 65.
Mentions: To efficiently present antigens to naïve T cells, immature DC must be activated to mature, a process accompanied by up-regulation of MHC and costimulatory molecules [24]. To investigate whether S. Typhi drives DC maturation, we evaluated the DC surface expression of CD80 and CD83 costimulatory molecules after different stimulatory conditions. Unstimulated DC (media) were used as negative controls. We observed that DC pulsed with live S. Typhi increased their surface expression of CD80 and CD83 in a dose-dependent manner (Fig. 1A) with levels comparable to those induced following exposure to LPS, a potent DC maturation factor [25] (Fig. 1B). Increases, albeit at lower levels, were also apparent when DC were pulsed with heat-inactivated S. Typhi demonstrating that neither bacterial infection nor viability was required for the observed effects. These results are in agreement with others using S. Typhimurium in a mouse model [26]. However, the exposure of DC to S. Typhi-infected blasts induced comparable or higher levels of CD80 and CD83 expression on DC than those induced by exposure of DC to live S. Typhi or LPS (Fig. 1B). Of interest, the expression level of CD80 and CD83 molecules on DC pulsed with not-infected blasts were similar to those observed in DC cultured in media alone (Fig. 1B). In conclusion, the appearance of DC exhibiting higher levels of CD83 and CD80 molecules after incubation with S. Typhi antigens demonstrated that S. Typhi drives DC maturation in humans.

Bottom Line: Typhi-infected human cells and release high levels of IFN-gamma and IL-12p70, leading to the subsequent presentation of bacterial antigens and triggering the induction of memory T cells, mostly CD3(+)CD8(+)CD45RA(-)CD62L(-) effector/memory T cells.This study is the first to demonstrate the effect of S.Typhi.

View Article: PubMed Central - PubMed

Affiliation: Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA. rmezghan@medicine.umaryland.edu

ABSTRACT

Background: The emergence of antibiotic-resistant strains of Salmonella enterica serovar Typhi (S. Typhi), the etiologic agent of typhoid fever, has aggravated an already important public health problem and added new urgency to the development of more effective typhoid vaccines. To this end it is critical to better understand the induction of immunity to S. Typhi. CD8(+) T cells are likely to play an important role in host defense against S. Typhi by several effector mechanisms, including killing of infected cells and IFN-gamma secretion. However, how S. Typhi regulates the development of specific CD8(+) responses in humans remains unclear. Recent studies in mice have shown that dendritic cells (DC) can either directly (upon uptake and processing of Salmonella) or indirectly (by bystander mechanisms) elicit Salmonella-specific CD8(+) T cells.

Methodology/principal findings: We report here that upon infection with live S. Typhi, human DC produced high levels of pro-inflammatory cytokines IL-6, IL-8 and TNF-alpha, but low levels of IL-12 p70 and IFN-gamma. In contrast, DC co-cultured with S. Typhi-infected cells, through suicide cross-presentation, uptake S. Typhi-infected human cells and release high levels of IFN-gamma and IL-12p70, leading to the subsequent presentation of bacterial antigens and triggering the induction of memory T cells, mostly CD3(+)CD8(+)CD45RA(-)CD62L(-) effector/memory T cells.

Conclusions/significance: This study is the first to demonstrate the effect of S. Typhi on human DC maturation and on their ability to prime CD8(+) cells and highlights the significance of these phenomena in eliciting adaptive immunity to S. Typhi.

Show MeSH
Related in: MedlinePlus