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Porphyromonas gingivalis Fimbriae Induce Osteoclastogenesis via Toll-like Receptors in RAW264 Cells
Yuki Suzuki1, Takeshi Kikuchi1, Hisashi Goto1
1Department of Periodontology, School of Dentistry, Aichi Gakuin University, 2-11 Suemori-dori, Chikusa-ku, Nagoya 464-8651, Japan.
Abstract:
The effect of Mfa1 fimbriae of Porphyromonas gingivalis on the progression of bone resorption remains unclear, especially compared with another fimbriae, FimA. We investigated the effect of Mfa1 on osteoclastogenesis together with FimA. We also investigated the role of Toll-like receptors (TLRs) in Mfa1 recognition during osteoclast differentiation. Receptor activator of nuclear factor κβ ligand (RANKL)-prestimulated RAW264 cells were used to examine the effects of purified Mfa1 fimbriae. The number of osteoclasts was examined by tartrate-resistant acid phosphate (TRAP) staining, osteoclast activation was investigated by bone resorption assays, and gene expression of differentiation markers was examined by quantitative real-time PCR. Transfection of Tlr2 and Tlr4 siRNAs into RAW264 cells was also employed and their role in Mfa1 recognition was investigated. Mfa1 effectively induced the formation of TRAP-positive multinucleated cells and activated osteoclasts. Mfa1 also increased gene expression of Acp5, Mmp9, and Ctsk in RANKL-prestimulated RAW264 cells compared with the control. The osteoclastogenesis induced by Mfa1 was significantly decreased in cells transfected with Tlr2 or Tlr4 siRNAs compared with control siRNA. Our results revealed the role of Mfa1 fimbriae in osteoclastogenesis that may contribute to the partial elucidation of the mechanisms of periodontal disease progression and the development of new therapeutic strategies.
Insights
Porphyromonas gingivalis Mfa1 fimbriae promote osteoclast formation and bone resorption, contributing to periodontal disease. Toll-like receptors TLR2 and TLR4 mediate Mfa1
Area of Science:
- Oral microbiology
- Immunology
- Periodontology
Background:
- The role of Porphyromonas gingivalis Mfa1 fimbriae in bone resorption, a key feature of periodontal disease, is not fully understood.
- Comparison with FimA fimbriae is needed to clarify Mfa1's specific contribution.
Purpose of the Study:
- To investigate the effect of Mfa1 fimbriae on osteoclastogenesis and bone resorption.
- To elucidate the involvement of Toll-like receptors (TLRs) in Mfa1 recognition during osteoclast differentiation.
Main Methods:
- RAW264 cells were stimulated with purified Mfa1 fimbriae after prestimulation with RANKL.
- Osteoclast formation was assessed by TRAP staining, bone resorption by resorption assays, and gene expression by qPCR.
- The role of TLR2 and TLR4 was investigated using siRNA transfections.
Main Results:
- Mfa1 fimbriae significantly induced osteoclast formation and activation, evidenced by TRAP-positive multinucleated cells and bone resorption.
- Mfa1 increased the expression of osteoclast differentiation markers (Acp5, Mmp9, Ctsk).
- Osteoclastogenesis induced by Mfa1 was significantly reduced when TLR2 or TLR4 were silenced.
Conclusions:
- Mfa1 fimbriae play a crucial role in promoting osteoclastogenesis.
- TLR2 and TLR4 are involved in Mfa1 recognition and subsequent osteoclast differentiation.
- These findings contribute to understanding periodontal disease mechanisms and may inform new therapeutic strategies.
