A bacterial glycan core linked to surface (S)-layer proteins modulates host immunity through Th17 suppression

Area of Science:

• Microbiology
• Immunology
• Oral Health

Background:

• Tannerella forsythia is a key pathogen in periodontitis, a disease causing tooth loss.
• This bacterium possesses a unique O-linked glycan core on its surface layer (S-layer) and glycoproteins.
• This glycan structure is crucial for bacterial survival and pathogenesis.

Purpose of the Study:

• To investigate the role of the T. forsythia glycan core in modulating host immune responses.
• To determine if the glycan core influences T-helper 17 (Th17) cell differentiation and function.
• To evaluate the therapeutic potential of targeting bacterial glycosylation in periodontitis.

Main Methods:

• Infection of mice with wild-type and mutant T. forsythia strains lacking the glycan core.
• Analysis of dendritic cell effector functions and T-helper cell responses (Th17).
• Assessment of periodontal bone loss as a measure of disease severity.

Main Results:

• The terminal motif of the glycan core suppresses dendritic cell functions and Th17 responses.
• Mice infected with the mutant strain (lacking glycan core) showed increased Th17 responses and reduced bone loss.
• T. forsythia appears to induce a Toll-like receptor 2-Th2 inflammatory axis contributing to bone destruction.

Conclusions:

• Surface glycosylation of T. forsythia is a mechanism for immune evasion, likely ensuring pathogen persistence by suppressing Th17 responses.
• Targeting bacterial glycans presents a potential therapeutic strategy against periodontitis and other infectious diseases.