Fusobacterium spp. target human CEACAM1 via the trimeric autotransporter adhesin CbpF

Area of Science:

• Microbiology
• Cell Biology
• Oral Biology

Background:

• Pathogenic bacteria like Neisseria meningitidis, Haemophilus influenzae, and Moraxella catarrhalis target CEACAM family members, particularly CEACAM1, on respiratory epithelia.
• CEACAM1 is also highly expressed on cells at the dentogingival junction, suggesting a potential role in oral bacterial colonization.

Purpose of the Study:

• To investigate whether oral bacteria utilize CEACAM1 for colonization and invasion of gingival tissues.
• To identify specific oral bacterial species and their adhesion mechanisms involved in CEACAM1 binding.

Main Methods:

• Screening of 59 oral bacterial isolates from 49 species for CEACAM1 binding.
• Testing of Fusobacterium species (F. nucleatum, F. vincentii, F. polymorphum, F. animalis) for CEACAM1 binding properties.
• Identification and characterization of the bacterial adhesin mediating CEACAM1 interaction.

Main Results:

• Fusobacterium nucleatum (Fn) and Fusobacterium vincentii (Fv) strains exhibited CEACAM1 binding.
• CEACAM1 adhesion was mediated by a trimeric autotransporter adhesin (TAA).
• A novel adhesin, named CEACAM binding protein of Fusobacterium (CbpF), was identified and found in the majority of unspeciated Fusobacterium isolates.

Conclusions:

• A subset of Fusobacterium species, including F. nucleatum and F. vincentii, can target human CEACAM1.
• The newly identified CbpF adhesin is responsible for CEACAM1 binding in these Fusobacterium species.
• This interaction highlights a potential mechanism for Fusobacterium colonization of gingival tissues.