Differential Responses of Pattern Recognition Receptors to Outer Membrane Vesicles of Three Periodontal Pathogens

Area of Science:

• Microbiology
• Immunology
• Periodontal disease research

Background:

• Periodontal pathogens like Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia are implicated in chronic periodontitis.
• Outer membrane vesicles (OMVs) are released by bacteria and play roles in inter-bacterial communication and host immune modulation.
• Understanding OMV production and immunogenicity is crucial for elucidating disease pathogenesis.

Purpose of the Study:

• To produce and characterize OMVs from key periodontal pathogens.
• To compare the OMV production levels among P. gingivalis, T. denticola, and T. forsythia.
• To investigate the differential immune responses induced by these pathogen-derived OMVs.

Main Methods:

• Tangential flow ultrafiltration, ultracentrifugation, and Optiprep density gradient separation were used for OMV purification.
• Cryo-transmission electron microscopy (Cryo-TEM) and light scattering assessed OMV size and structure.
• Nanoparticle flow cytometry enumerated OMV production, and HEK-Blue cells expressing pattern recognition receptors (PRRs) measured immune responses.

Main Results:

• OMVs were confirmed as single lipid bilayers with modal diameters ranging from 75 to 158 nm.
• Porphyromonas gingivalis exhibited the highest OMV production rate compared to T. denticola and T. forsythia.
• P. gingivalis OMVs induced potent TLR2, TLR4, and moderate TLR7/8/9, NOD1/2 responses; T. forsythia and T. denticola OMVs elicited weaker immune reactions.

Conclusions:

• Periodontal pathogen OMVs display distinct compositional differences and varying immunogenic potentials.
• Differential PRR activation by OMVs suggests distinct roles in the inflammatory processes of chronic periodontitis.
• P. gingivalis OMVs are potent immune stimulators, highlighting their significance in periodontitis pathogenesis.