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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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S. Typhi-infected blasts are the most effective stimulus in inducing DC to secrete pro-inflammatory cytokines in vitro.Immature DC were cultured in the absence (media) or in presence of live or heat-killed S. Typhi at a MOI of 10∶1, uninfected or S. Typhi-infected autologous blasts at DC∶blast ratio of 4∶1. S. Typhi-infected blasts only (without adding DC) were included as controls. After 48 h the supernants were harvested and cytokine production was measured using the flow cytometry-based BD cytometric bead array (CBA) assay. Bar graphs show mean + SE of 6 experiments using 5 different donors (*, p<0.05 compared with DC pulsed with S. Typhi-infected cells).
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pone-0005879-g002: S. Typhi-infected blasts are the most effective stimulus in inducing DC to secrete pro-inflammatory cytokines in vitro.Immature DC were cultured in the absence (media) or in presence of live or heat-killed S. Typhi at a MOI of 10∶1, uninfected or S. Typhi-infected autologous blasts at DC∶blast ratio of 4∶1. S. Typhi-infected blasts only (without adding DC) were included as controls. After 48 h the supernants were harvested and cytokine production was measured using the flow cytometry-based BD cytometric bead array (CBA) assay. Bar graphs show mean + SE of 6 experiments using 5 different donors (*, p<0.05 compared with DC pulsed with S. Typhi-infected cells).

Mentions: Another hallmark of DC maturation is the production of cytokines, such as IL-12 and IFN-γ, which are critical for the induction of CMI [27]. Because IL-12 and IFN-γ are essential for resistance to Salmonella infection in mice [28], [29], as they are likely to be in humans [5], [6], [9], [30], [31], it was of importance to evaluate the effect of S. Typhi on cytokine production by DC. To this end, DC were pulsed with heat-killed S. Typhi or wild-type S. Typhi at a 10∶1 MOI, uninfected or S. Typhi-infected blasts at a 1∶4 blast to DC ratio during 48 hours. DC pulsed with heat-killed or live S. Typhi produced high levels of pro-inflammatory cytokines such as IL-6, IL-8 and TNF-α but only low levels or no IL-12 p70 (Fig. 2). This low or lack of IL-12 secretion does not seems to be the result of IL-10 production by these cells. DC pulsed with heat-killed or live S. Typhi elicited levels of IL-10 only slightly different than those detected in culture supernatants of DC incubated in medium alone (Fig. 2).


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)

S. Typhi-infected blasts are the most effective stimulus in inducing DC to secrete pro-inflammatory cytokines in vitro.Immature DC were cultured in the absence (media) or in presence of live or heat-killed S. Typhi at a MOI of 10∶1, uninfected or S. Typhi-infected autologous blasts at DC∶blast ratio of 4∶1. S. Typhi-infected blasts only (without adding DC) were included as controls. After 48 h the supernants were harvested and cytokine production was measured using the flow cytometry-based BD cytometric bead array (CBA) assay. Bar graphs show mean + SE of 6 experiments using 5 different donors (*, p<0.05 compared with DC pulsed with S. Typhi-infected cells).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2691582&req=5

pone-0005879-g002: S. Typhi-infected blasts are the most effective stimulus in inducing DC to secrete pro-inflammatory cytokines in vitro.Immature DC were cultured in the absence (media) or in presence of live or heat-killed S. Typhi at a MOI of 10∶1, uninfected or S. Typhi-infected autologous blasts at DC∶blast ratio of 4∶1. S. Typhi-infected blasts only (without adding DC) were included as controls. After 48 h the supernants were harvested and cytokine production was measured using the flow cytometry-based BD cytometric bead array (CBA) assay. Bar graphs show mean + SE of 6 experiments using 5 different donors (*, p<0.05 compared with DC pulsed with S. Typhi-infected cells).
Mentions: Another hallmark of DC maturation is the production of cytokines, such as IL-12 and IFN-γ, which are critical for the induction of CMI [27]. Because IL-12 and IFN-γ are essential for resistance to Salmonella infection in mice [28], [29], as they are likely to be in humans [5], [6], [9], [30], [31], it was of importance to evaluate the effect of S. Typhi on cytokine production by DC. To this end, DC were pulsed with heat-killed S. Typhi or wild-type S. Typhi at a 10∶1 MOI, uninfected or S. Typhi-infected blasts at a 1∶4 blast to DC ratio during 48 hours. DC pulsed with heat-killed or live S. Typhi produced high levels of pro-inflammatory cytokines such as IL-6, IL-8 and TNF-α but only low levels or no IL-12 p70 (Fig. 2). This low or lack of IL-12 secretion does not seems to be the result of IL-10 production by these cells. DC pulsed with heat-killed or live S. Typhi elicited levels of IL-10 only slightly different than those detected in culture supernatants of DC incubated in medium alone (Fig. 2).

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