Regulation of matrix metalloproteinase-1 by Filifactor alocis in human gingival and monocytic cells

OBJECTIVES Periodontitis is a highly prevalent chronic inflammatory disease caused by periodontopathogens, such as Filifactor alocis. This study sought to examine the matrix metalloproteinase (MMP)-1 synthesis by monocytic and fibroblastic cells in response to F. alocis and to unravel the underlying cellular mechanisms. MATERIAL AND METHODS Gingival biopsies from periodontally healthy and periodontitis individuals were analyzed for the presence of F. alocis and MMP-1 by RT-PCR. Human gingival fibroblastic (HGF-1) and monocytic (THP-1) cells were stimulated with F. alocis in the presence and absence of a blocking toll-like receptor (TLR)2 antibody or specific inhibitors against MAPKs. MMP-1 expression and protein levels were studied by RT-PCR and ELISA, respectively. RESULTS F. alocis was highly prevalent in biopsies from periodontitis patients but barely present in the healthy gingiva. Significantly higher MMP-1 expression levels were found in the inflamed gingiva as compared with healthy biopsies. F. alocis caused a significant and dose-dependent MMP-1 upregulation in both cells. The stimulatory effect of F. alocis on MMP-1 was TLR2- and MAPK-dependent and more pronounced on THP-1 cells as compared with HGF-1 cells. CONCLUSIONS Our results demonstrate that F. alocis and MMP-1 are more prevalent at periodontitis sites. Additionally, our study provides original evidence that F. alocis can stimulate MMP-1 production by fibroblastic and monocytic cells, suggesting that F. alocis may contribute to periodontal breakdown through MMP-1. CLINICAL RELEVANCE F. alocis and MMP-1 are linked to each other and key players in periodontitis, which may have significant implications for future diagnostic and treatment strategies.