OBJECTIVE: The serotype b of Aggregatibacter actinomycetemcomitans (A.
actinomycetemcomitans) induces higher cytokine production in dendritic cells
(DCs) compared with the other serotypes. However, this increased
immunostimulatory potential was modified when DCs were co-infected with the
other A. actinomycetemcomitans serotypes. This study aimed to analyze whether
the production of interferon gamma (IFN-γ), C-reactive protein (CRP), matrix
metalloproteinase (MMP)-2, and MMP-9, as well as the activity of osteoclasts,
also varies when DCs are co-infected with the A. actinomycetemcomitans
serotypes.
MATERIALS AND METHODS: Human DCs were stimulated with the A.
actinomycetemcomitans serotypes using the following stimulatory conditions:
serotype a/b/c/a+b/a+c/b+c/a+b+c. The IFN-γ, CRP, and MMP-2 levels were
quantified by ELISA. The active form of MMP-9 was quantified using fluorescent
functional assays. The MMP-2 gelatinolytic activity was identified by zymogram.
The osteoclast activity was determined by quantifying the TRAP expression and
resorption-pit formation using cytochemistry and osteoassays.
RESULTS: Higher levels of IFN-γ, CRP, MMP-2, MMP-9, and osteoclast activity were
detected when DCs were stimulated with the serotype b of A.
actinomycetemcomitans compared with the others. This increased immunostimulatory
potential attributed to serotype b diminished when DCs were co-infected with the
serotype a.
CONCLUSIONS: This study provides new insights into the virulence of A.
actinomycetemcomitans and reveals important differences in the immunostimulatory
and pro-destructive potential among its serotypes.
