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Pro-inflammatory cytokines can act as intracellular modulators of commensal bacterial virulence.

Mahdavi J, Royer PJ, Sjölinder HS, Azimi S, Self T, Stoof J, Wheldon LM, Brännström K, Wilson R, Moreton J, Moir JW, Sihlbom C, Borén T, Jonsson AB, Soultanas P, Ala'Aldeen DA - Open Biol (2013)

Bottom Line: Interactions between commensal pathogens and hosts are critical for disease development but the underlying mechanisms for switching between the commensal and virulent states are unknown.This uptake is mediated by type IV pili (Tfp) and reliant on the PilT ATPase activity.We propose a novel mechanism by which pathogens use the twitching motility mode of the Tfp machinery for sensing and importing host elicitors, aligning with the inflamed environment and switching to the virulent state.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Molecular Bacteriology and Immunology Group, University of Nottingham, Nottingham NG7 2RD, UK.

ABSTRACT
Interactions between commensal pathogens and hosts are critical for disease development but the underlying mechanisms for switching between the commensal and virulent states are unknown. We show that the human pathogen Neisseria meningitidis, the leading cause of pyogenic meningitis, can modulate gene expression via uptake of host pro-inflammatory cytokines leading to increased virulence. This uptake is mediated by type IV pili (Tfp) and reliant on the PilT ATPase activity. Two Tfp subunits, PilE and PilQ, are identified as the ligands for TNF-α and IL-8 in a glycan-dependent manner, and their deletion results in decreased virulence and increased survival in a mouse model. We propose a novel mechanism by which pathogens use the twitching motility mode of the Tfp machinery for sensing and importing host elicitors, aligning with the inflamed environment and switching to the virulent state.

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Confocal images of Nm uptake of human cytokines. (a) Detection of intracellular TNF-α into the meningococcal cytoplasm. Nm live cells were induced with Atto680-labelled recombinant proteins (TNF-α or Galactin-3). Cells were stained with anti-PorA monoclonal antibody and DPI. Merged images depict co-localization of Atto680 (red) and monoclonal anti-PorA antibody (green), DPI (blue) and +TNF-α680 induced (yellow). Non-induced Nm MC58 (CT) or Gal-3680 labelled was used as negative control. In addition, the uptake of labelled TNF-α680 was inhibited by using non-labelled TNF-α. Insets shown are at 2.5 times magnification. Images are single sections (300 nm) and data were collected from different fluorophores in separate channels. (b) Transmission electron micrograph of Nm TNF-α uptake in mice peritoneum and blood. TEM macrograph analysis of TNF-α uptake by Nm wild-type strain and ΔpglC/L mutant isolated from peritoneum and blood at 4 h post-infected mice. Treated samples with only secondary antibody were used as negative control (CT). Wild-type MC58 strain shows accumulation of gold particles inside or on the surface of the bacteria (red arrow). The cells shown in this image are representative of approximately 66% and 50% of the analysed bacterial population in peritoneum and blood, respectively. No uptake was observed in images of TNF-α ΔpglC/L mutants, indicating that uptake of cytokines requires the glycosylated form of PilE protein. The scale bar represents 500 nm and the insets represent two times magnification.
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RSOB130048F4: Confocal images of Nm uptake of human cytokines. (a) Detection of intracellular TNF-α into the meningococcal cytoplasm. Nm live cells were induced with Atto680-labelled recombinant proteins (TNF-α or Galactin-3). Cells were stained with anti-PorA monoclonal antibody and DPI. Merged images depict co-localization of Atto680 (red) and monoclonal anti-PorA antibody (green), DPI (blue) and +TNF-α680 induced (yellow). Non-induced Nm MC58 (CT) or Gal-3680 labelled was used as negative control. In addition, the uptake of labelled TNF-α680 was inhibited by using non-labelled TNF-α. Insets shown are at 2.5 times magnification. Images are single sections (300 nm) and data were collected from different fluorophores in separate channels. (b) Transmission electron micrograph of Nm TNF-α uptake in mice peritoneum and blood. TEM macrograph analysis of TNF-α uptake by Nm wild-type strain and ΔpglC/L mutant isolated from peritoneum and blood at 4 h post-infected mice. Treated samples with only secondary antibody were used as negative control (CT). Wild-type MC58 strain shows accumulation of gold particles inside or on the surface of the bacteria (red arrow). The cells shown in this image are representative of approximately 66% and 50% of the analysed bacterial population in peritoneum and blood, respectively. No uptake was observed in images of TNF-α ΔpglC/L mutants, indicating that uptake of cytokines requires the glycosylated form of PilE protein. The scale bar represents 500 nm and the insets represent two times magnification.

Mentions: The intracellular uptake of labelled TNF-α by Nm wild-type MC58 bacteria was confirmed by confocal imaging, whereas in control experiments there was no uptake of labelled Gal-3 (galectin 3), confirming the specificity of the uptake (figure 4a). Furthermore, pre-treatment of the bacteria with non-labelled TNF-α inhibited the uptake of labelled TNF-α (figure 4a), further confirming uptake specificity.Figure 4.


Pro-inflammatory cytokines can act as intracellular modulators of commensal bacterial virulence.

Mahdavi J, Royer PJ, Sjölinder HS, Azimi S, Self T, Stoof J, Wheldon LM, Brännström K, Wilson R, Moreton J, Moir JW, Sihlbom C, Borén T, Jonsson AB, Soultanas P, Ala'Aldeen DA - Open Biol (2013)

Confocal images of Nm uptake of human cytokines. (a) Detection of intracellular TNF-α into the meningococcal cytoplasm. Nm live cells were induced with Atto680-labelled recombinant proteins (TNF-α or Galactin-3). Cells were stained with anti-PorA monoclonal antibody and DPI. Merged images depict co-localization of Atto680 (red) and monoclonal anti-PorA antibody (green), DPI (blue) and +TNF-α680 induced (yellow). Non-induced Nm MC58 (CT) or Gal-3680 labelled was used as negative control. In addition, the uptake of labelled TNF-α680 was inhibited by using non-labelled TNF-α. Insets shown are at 2.5 times magnification. Images are single sections (300 nm) and data were collected from different fluorophores in separate channels. (b) Transmission electron micrograph of Nm TNF-α uptake in mice peritoneum and blood. TEM macrograph analysis of TNF-α uptake by Nm wild-type strain and ΔpglC/L mutant isolated from peritoneum and blood at 4 h post-infected mice. Treated samples with only secondary antibody were used as negative control (CT). Wild-type MC58 strain shows accumulation of gold particles inside or on the surface of the bacteria (red arrow). The cells shown in this image are representative of approximately 66% and 50% of the analysed bacterial population in peritoneum and blood, respectively. No uptake was observed in images of TNF-α ΔpglC/L mutants, indicating that uptake of cytokines requires the glycosylated form of PilE protein. The scale bar represents 500 nm and the insets represent two times magnification.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3814720&req=5

RSOB130048F4: Confocal images of Nm uptake of human cytokines. (a) Detection of intracellular TNF-α into the meningococcal cytoplasm. Nm live cells were induced with Atto680-labelled recombinant proteins (TNF-α or Galactin-3). Cells were stained with anti-PorA monoclonal antibody and DPI. Merged images depict co-localization of Atto680 (red) and monoclonal anti-PorA antibody (green), DPI (blue) and +TNF-α680 induced (yellow). Non-induced Nm MC58 (CT) or Gal-3680 labelled was used as negative control. In addition, the uptake of labelled TNF-α680 was inhibited by using non-labelled TNF-α. Insets shown are at 2.5 times magnification. Images are single sections (300 nm) and data were collected from different fluorophores in separate channels. (b) Transmission electron micrograph of Nm TNF-α uptake in mice peritoneum and blood. TEM macrograph analysis of TNF-α uptake by Nm wild-type strain and ΔpglC/L mutant isolated from peritoneum and blood at 4 h post-infected mice. Treated samples with only secondary antibody were used as negative control (CT). Wild-type MC58 strain shows accumulation of gold particles inside or on the surface of the bacteria (red arrow). The cells shown in this image are representative of approximately 66% and 50% of the analysed bacterial population in peritoneum and blood, respectively. No uptake was observed in images of TNF-α ΔpglC/L mutants, indicating that uptake of cytokines requires the glycosylated form of PilE protein. The scale bar represents 500 nm and the insets represent two times magnification.
Mentions: The intracellular uptake of labelled TNF-α by Nm wild-type MC58 bacteria was confirmed by confocal imaging, whereas in control experiments there was no uptake of labelled Gal-3 (galectin 3), confirming the specificity of the uptake (figure 4a). Furthermore, pre-treatment of the bacteria with non-labelled TNF-α inhibited the uptake of labelled TNF-α (figure 4a), further confirming uptake specificity.Figure 4.

Bottom Line: Interactions between commensal pathogens and hosts are critical for disease development but the underlying mechanisms for switching between the commensal and virulent states are unknown.This uptake is mediated by type IV pili (Tfp) and reliant on the PilT ATPase activity.We propose a novel mechanism by which pathogens use the twitching motility mode of the Tfp machinery for sensing and importing host elicitors, aligning with the inflamed environment and switching to the virulent state.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Molecular Bacteriology and Immunology Group, University of Nottingham, Nottingham NG7 2RD, UK.

ABSTRACT
Interactions between commensal pathogens and hosts are critical for disease development but the underlying mechanisms for switching between the commensal and virulent states are unknown. We show that the human pathogen Neisseria meningitidis, the leading cause of pyogenic meningitis, can modulate gene expression via uptake of host pro-inflammatory cytokines leading to increased virulence. This uptake is mediated by type IV pili (Tfp) and reliant on the PilT ATPase activity. Two Tfp subunits, PilE and PilQ, are identified as the ligands for TNF-α and IL-8 in a glycan-dependent manner, and their deletion results in decreased virulence and increased survival in a mouse model. We propose a novel mechanism by which pathogens use the twitching motility mode of the Tfp machinery for sensing and importing host elicitors, aligning with the inflamed environment and switching to the virulent state.

Show MeSH
Related in: MedlinePlus