Bacterial fimbriae activate human peripheral blood monocytes utilizing TLR2, CD14 and CD11a/CD18 as cellular receptors.

Bacterial fimbriae are associated with a specific adherence factor, adhesin, in their microbial etiology. Porphyromonas gingivalis, as an anaerobic Gram-negative periodontopathogenic organism, is known to possess fimbriae on its cell surfaces. In this study, we demonstrated that P. gingivalis fimbriae and an active synthetic peptide composed of residues 69 - 73 of thefimbrial subunit protein, ALTTE, induced IL-6 mRNA expression and cytokine production, p38 mitogen-activated protein (MAP) kinase phosphorylation, and NF-kappaB activation in human peripheral blood monocytes. P. gingivalis fimbriae and ALTTE also induced IL-6 production via human Toll-like receptor (TLR) 2, CD14, and CD11a/CD18 (LFA-1) molecules on human monocytes. These results suggest that P. gingivalis fimbriae and these degraded peptides may play an important role in the inflamed gingival and periodontal tissues seen in the development and progression of periodontal diseases.