Background and Objective: Dental peri-implantitis, which can be caused by several different
microbial factors, is characterized by inflammatory lesions of the surrounding hard and soft tissues
of an oral implant. Matrix Metalloproteinase 9 (MMP9) is thought to be involved in the pathogenesis
of peri-implantitis. However, the regulatory mechanism of MMP9 in peri-implantitis has not been fully
elucidated. In this study, we tried to evaluate the regulatory mechanism of MMP9 in peri-implantitis.
Methods: We collected Peri-Implant Crevicular Fluid (PICF) from ten healthy implants and ten periimplantitis
patients and compared their expression level of MMP9. We also cultured macrophages from
the peripheral blood of healthy volunteers infected by Porphyromonas gingivalis to reveal the regulatory
mechanism of MMP9 in peri-implantitis. Western blot, immunofluorescence staining and quantitative
Polymerase Chain Reaction (RT-PCR) were used to better characterize the mechanism of MMP9.
Results: The expression of MMP9 was up-regulated in peri-implantitis patient PICF and P. gingivalis
infected human macrophages. LOX-1, not dectin-1, was found to mediate MMP9 expression in human
macrophages with P. gingivalis infection. Expression of Erk1/2 was responsible for infection-induced
MMP9 expression. Finally, use of a broad-spectrum metalloproteinase inhibitor impaired LOX-1 expression
in infected macrophages.
Conclusion: Our results demonstrate that MMP9 is involved in dental peri-implantitis and is regulated
by LOX-1 and Erk1/2. This LOX-1/MMP9 signaling pathway may represent a potential drug target for