Limits...
Host cell-derived lactate functions as an effector molecule in Neisseria meningitidis microcolony dispersal

View Article: PubMed Central - PubMed

ABSTRACT

The development of meningococcal disease, caused by the human pathogen Neisseria meningitidis, is preceded by the colonization of the epithelial layer in the nasopharynx. After initial adhesion to host cells meningococci form aggregates, through pilus-pilus interactions, termed microcolonies from which the bacteria later detach. Dispersal from microcolonies enables access to new colonization sites and facilitates the crossing of the cell barrier; however, this process is poorly understood. In this study, we used live-cell imaging to investigate the process of N. meningitidis microcolony dispersal. We show that direct contact with host cells is not required for microcolony dispersal, instead accumulation of a host-derived effector molecule induces microcolony dispersal. By using a host-cell free approach, we demonstrated that lactate, secreted from host cells, initiate rapid dispersal of microcolonies. Interestingly, metabolic utilization of lactate by the bacteria was not required for induction of dispersal, suggesting that lactate plays a role as a signaling molecule. Furthermore, Neisseria gonorrhoeae microcolony dispersal could also be induced by lactate. These findings reveal a role of host-secreted lactate in microcolony dispersal and virulence of pathogenic Neisseria.

No MeSH data available.


Related in: MedlinePlus

Host cells accelerate microcolony dispersal independent of direct contact.Microcolony formation and dispersal of N. meningitidis FAM20 (2 × 106 CFU/ml) were monitored for 8 h by live-cell time-lapse microscopy after infection of FaDu cells. (A) FaDu cells at confluences of 100%, 80%, 50%, 20% and 0% were infected with FAM20. (B) The dispersal of FAM20 microcolonies on FaDu cells at 50% confluence was observed with live-cell time-lapse microscopy. Representative images are shown. Scale bar, 10 μm. (C) FaDu cells were infected with FAM20 or the ΔpilC1 mutant. (D) FAM20 infecting fixed (3.7% paraformaldehyde) or live FaDu cells. Data represent the mean ± SD for at least three individual experiments. *p < 0.05. ns, non-significant.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5383330&req=5

ppat.1006251.g001: Host cells accelerate microcolony dispersal independent of direct contact.Microcolony formation and dispersal of N. meningitidis FAM20 (2 × 106 CFU/ml) were monitored for 8 h by live-cell time-lapse microscopy after infection of FaDu cells. (A) FaDu cells at confluences of 100%, 80%, 50%, 20% and 0% were infected with FAM20. (B) The dispersal of FAM20 microcolonies on FaDu cells at 50% confluence was observed with live-cell time-lapse microscopy. Representative images are shown. Scale bar, 10 μm. (C) FaDu cells were infected with FAM20 or the ΔpilC1 mutant. (D) FAM20 infecting fixed (3.7% paraformaldehyde) or live FaDu cells. Data represent the mean ± SD for at least three individual experiments. *p < 0.05. ns, non-significant.

Mentions: The aim of this study was to investigate the process of N. meningitidis microcolony dispersal. To evaluate the necessity of direct interaction with host cells, we monitored the timing of the dispersal upon infection of pharyngeal epithelial FaDu cells at different confluences using live-cell time-lapse microscopy. The dispersal phase began after approximately 4.5 h in the presence of cells and after 6.5 h in the absence of cells (Fig 1A). The total time the bacteria spent in the dispersal phase was drastically shorter in the presence of cells, lasting approximately 20 min, while in the absence of cells bacteria were still detaching from microcolonies after 8 h of incubation (Fig 1A). Microcolonies on cells at confluences of 100%, 80%, 50% and 20% showed no differences in dispersal phase length. Interestingly, the microcolonies that were not in direct contact with host cells (Fig 1B) also showed a synchronized and short dispersal phase similar to microcolonies that were in direct contact with host cells (S1A Fig).


Host cell-derived lactate functions as an effector molecule in Neisseria meningitidis microcolony dispersal
Host cells accelerate microcolony dispersal independent of direct contact.Microcolony formation and dispersal of N. meningitidis FAM20 (2 × 106 CFU/ml) were monitored for 8 h by live-cell time-lapse microscopy after infection of FaDu cells. (A) FaDu cells at confluences of 100%, 80%, 50%, 20% and 0% were infected with FAM20. (B) The dispersal of FAM20 microcolonies on FaDu cells at 50% confluence was observed with live-cell time-lapse microscopy. Representative images are shown. Scale bar, 10 μm. (C) FaDu cells were infected with FAM20 or the ΔpilC1 mutant. (D) FAM20 infecting fixed (3.7% paraformaldehyde) or live FaDu cells. Data represent the mean ± SD for at least three individual experiments. *p < 0.05. ns, non-significant.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383330&req=5

ppat.1006251.g001: Host cells accelerate microcolony dispersal independent of direct contact.Microcolony formation and dispersal of N. meningitidis FAM20 (2 × 106 CFU/ml) were monitored for 8 h by live-cell time-lapse microscopy after infection of FaDu cells. (A) FaDu cells at confluences of 100%, 80%, 50%, 20% and 0% were infected with FAM20. (B) The dispersal of FAM20 microcolonies on FaDu cells at 50% confluence was observed with live-cell time-lapse microscopy. Representative images are shown. Scale bar, 10 μm. (C) FaDu cells were infected with FAM20 or the ΔpilC1 mutant. (D) FAM20 infecting fixed (3.7% paraformaldehyde) or live FaDu cells. Data represent the mean ± SD for at least three individual experiments. *p < 0.05. ns, non-significant.
Mentions: The aim of this study was to investigate the process of N. meningitidis microcolony dispersal. To evaluate the necessity of direct interaction with host cells, we monitored the timing of the dispersal upon infection of pharyngeal epithelial FaDu cells at different confluences using live-cell time-lapse microscopy. The dispersal phase began after approximately 4.5 h in the presence of cells and after 6.5 h in the absence of cells (Fig 1A). The total time the bacteria spent in the dispersal phase was drastically shorter in the presence of cells, lasting approximately 20 min, while in the absence of cells bacteria were still detaching from microcolonies after 8 h of incubation (Fig 1A). Microcolonies on cells at confluences of 100%, 80%, 50% and 20% showed no differences in dispersal phase length. Interestingly, the microcolonies that were not in direct contact with host cells (Fig 1B) also showed a synchronized and short dispersal phase similar to microcolonies that were in direct contact with host cells (S1A Fig).

View Article: PubMed Central - PubMed

ABSTRACT

The development of meningococcal disease, caused by the human pathogen Neisseria meningitidis, is preceded by the colonization of the epithelial layer in the nasopharynx. After initial adhesion to host cells meningococci form aggregates, through pilus-pilus interactions, termed microcolonies from which the bacteria later detach. Dispersal from microcolonies enables access to new colonization sites and facilitates the crossing of the cell barrier; however, this process is poorly understood. In this study, we used live-cell imaging to investigate the process of N. meningitidis microcolony dispersal. We show that direct contact with host cells is not required for microcolony dispersal, instead accumulation of a host-derived effector molecule induces microcolony dispersal. By using a host-cell free approach, we demonstrated that lactate, secreted from host cells, initiate rapid dispersal of microcolonies. Interestingly, metabolic utilization of lactate by the bacteria was not required for induction of dispersal, suggesting that lactate plays a role as a signaling molecule. Furthermore, Neisseria gonorrhoeae microcolony dispersal could also be induced by lactate. These findings reveal a role of host-secreted lactate in microcolony dispersal and virulence of pathogenic Neisseria.

No MeSH data available.


Related in: MedlinePlus