Discussion : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
Our present study showed that anti-RANKL antibody can significantly inhibit the bone loss in peri-implantitis and additional miR-146a treatment will enhance this inhibition through its anti-inflammation effects via TLR2/4 signaling. This is the first report in a murine model of peri-implantitis to demonstrate that anti-RANKL antibody and miR-146a together can significantly reduce bone resorption and inflammation in peri-implantitis, suggesting a potential therapeutic strategy for peri-implantitis patients. Moreover, the data showed that anti-bone loss effects of anti-RANKL antibody are independent of TLR2 and TLR4 and anti-RANKL antibody alone did not affect peri-implant inflammatory infiltration, suggesting that RANKL modulation of bone loss is downstream of peri-implant inflammation and more directly towards bone resorption. However, anti-RANKL antibody + miR-146a treatment showed significantly stronger inhibition of bone loss than anti-RANKL antibody alone treatment, indicating that the suppression of inflammation can be used to reduce peri-implantitis bone loss by removing additional RANKL-independent etiology and pathogenesis of bone loss. These data (Fig. 1–5, Supplemental Table S1) showed that anti-inflammatory miR-146a enhance anti-RANKL-induced inhibition of peri-implant bone resorption through the regulation of TLR2/4 signaling and inhibition of TNF-α expression. Thus, the ideal osteoimmunological treatment for peri-implantitis should include both direct anti-osteoclastogenesis and anti-inflammation components.
As innate immune recognition receptors, TLR family plays a central role in innate immunity, inflammation, cell survival, and proliferation [5, 26, 37, 38]. TLR2 and TLR4 are essential signaling proteins in progression of inflammation and related bone metabolism in periodontitis [28, 29, 39, 40]. However, little is known about the functions of TLR2 and TLR4 signaling in peri-implantitis. In the present study, we investigated the changes in bone resorption, gingival TNF-α (pro-inflammatory marker) mRNA levels, and gingival soluble RANKL protein levels in ligation-induced experimental peri-implantitis in WT and TLR2/4 KO mice with or without anti-RANKL antibody alone treatment and anti-RANKL antibody + miR-146a treatment. The results showed that anti-bone loss effects of anti-RANKL antibody are TLR2/4 independent but anti-inflammation and related anti-bone loss effects of miR-146a are TLR2/4 dependent, suggesting that TLR2/4 signaling is crucial for RANKL-independent, inflammation-induced bone loss in peri-implantitis.
Serial posts:
- Abstract : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- Abstract : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- Background : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- Background : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- Methods : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- Methods : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- Methods : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [3]
- Results : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- Results : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- Discussion : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- Discussion : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- Conclusions : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Availability of data and materials : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Abbreviations : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- References : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- References : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- References : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [3]
- References : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [4]
- Acknowledgements : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Funding : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Author information : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [1]
- Author information : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling [2]
- Ethics declarations : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Additional information : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Supplementary information : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Rights and permissions : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- About this article : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through TLR2/4 signaling
- Table 1 Success rate (SR) of osseointegrated implants 4 weeks after implant placement : RANKL blockade alleviates peri-implant bone loss and is enhanced by anti-inflammatory microRNA-146a through
- Fig. 1. Mouse model of ligature-induced experimental peri-implantitis. (a) Tooth extraction: left maxillary first and second molars extracted at 4 weeks old and the tooth extraction socket healed well with smooth gingiva surface after 6 weeks post-extraction. Implant placement: implant was put in alveolar bone without flap elevation. Ligature placement: at 4 weeks post-implant, 7-0 ligatures were applied under the fixture head. Gingival injection: injections for animals were administered three times on days 3, 6, and 9 during 14 days ligation period. Sample collection: 14 days post-ligation, the gingival tissues and the skulls were collected. (b) Images depicting processing steps of the experimental design (scale bar, 500 μm) : RANKL blockade alleviates peri-implant
- Fig. 2. Anti-RANKL and anti-RANKL+miR-146a treatments decreased ligature-induced bone resorption with different patterns in experimental peri-implantitis of WT and TLR2/4 KO mice. Buccal side images of the defleshed skulls were taken of the control (non-ligation) group, ligation (non-treatment) group, ligation with anti-RANKL antibody (ligation+AR) treatment group, and ligation with anti-RANKL antibody + miR-146a (ligation+A+MiR) treatment group in WT mice and TLR2/4 KO mice (a) (scale bar, 500 μm). The bone resorption area based on these images was measured and analyzed for WT mice (b) and TLR2/4 KO mice (c) (mean ± SD, n = 6, *p < 0.05, **p < 0.01, SEM, standard error of difference between two means). Three dimension (3D) images from μCT were collected and analyzed for WT mice (d) and TLR4 KO mice (e) (mean ± SD, n = 6, *p < 0.05, **p < 0.01) : RANKL blockade alleviates peri-implant
- Fig. 3. Anti-RANKL and anti-RANKL+miR-146a treatments decreased TRAP-positive cell quantities with different patterns in experimental peri-implantitis of WT and TLR2/4 KO mice. TRAP-positive cells (red color) with 3 or more nuclei were considered osteoclasts and were shown in the control group, ligation group, ligation with anti-RANKL antibody treatment group, and ligation with anti-RANKL antibody + miR-146a treatment group in WT mice and TLR2/4 KO mice (a) (Im, implant; Av, alveolar bone; scale bar, 100 μm). The quantities of TRAP-positive cells were analyzed in each group of WT mice (b) and TLR2/4 KO mice (c) (mean ± SD, n = 6, **p < 0.01) : RANKL blockade alleviates peri-implant
- Fig. 4. Anti-RANKL and anti-RANKL+miR-146a treatments decreased the inflammatory cell infiltration of the implant gingival tissues with different patterns in experimental peri-implantitis of WT and TLR2/4 KO mice. HE staining of the gingival tissue around implants were performed in the control group, ligation group, ligation with anti-RANKL antibody treatment group, and ligation with anti-RANKL antibody + miR-146a treatment group in WT mice and TLR2/4 KO mice (a) (scale bar, 100 μm). Inflammatory cell numbers were measured and analyzed in each group of WT mice (b) and TLR2/4 KO mice (c) (mean ± SD, n = 6, **p < 0.01) : RANKL blockade alleviates peri-implant
- Fig. 5. Anti-RANKL and anti-RANKL+miR-146a treatments decreased gingival mRNA expression of TNF-α and RANKL with different patterns in experimental peri-implantitis of WT and TLR2/4 KO mice. Gingival tissues around ligatured implants and non-ligation implants were excised and processed for RT-qPCR analysis to determine mRNA level of TNF-α of WT mice (a) and TLR2/4 KO mice (b) (mean ± SD, n = 6, *p < 0.05, **p < 0.01) and mRNA level of RANKL of WT mice (c) and TLR2/4 KO mice (d) (mean ± SD, n = 6, *p < 0.05, **p < 0.01). : RANKL blockade alleviates peri-implant