| Background: Peri-implantitis is a plaque-associated pathological condition occurring in tissues around dental implants,characterized by inflammation in the peri-implant mucosa and subsequent progressive loss of supporting bone.Bacteria accumulation around the implant surface and the abutment is the leading cause of peri-implant inflammation.These pathogenic bacteria gather and form into biofilm.In the process of biofilm formation of the pathogens,N-acyl homoserine lactone(AHL),as a kind of self-induced molecules(AI)for intra-specific communication of bacteria,plays an important role of signal transmitter in the quorum sensing(QS)system,regulating the proliferation and adhesion of bacteria and other specific biological behaviors.N-acyl homoserine lactonase(AHL lactonase)is a kind of quenching enzyme targeting at AHL molecules by hydrolyzing of homoserine lactone ring,blocking the transduction of signal molecules,interfering with QS system,and inhibiting bacterial biofilm formation.In the past decade,studies have confirmed that AHL lactonase can inhibit the pathogenicity of Pseudomonas aeruginosa,Burkholderia cepacia,Erwinia carotovora and Pectobacterium.However,there are few reports on the application of AHL lactonase in oral infectious diseases.Therefore,the purpose of this study is to explore the effect of Est816 on the physiological activities of P.gingivalis,one of the dominant pathogens around the implants and to study the effect of Est816 on canine peri-implant inflammation,so as to provide a theoretical basis for the application of Est816 in the control of periodontal pathogenic microorganisms and effective prevention and treatment of periodontitis and periimplantitis.Methods: After polished by metallographic sandpaper,titanium specimens were used as substrates to load bacterial suspension cultured with Est816 solutions.The properties of Est816 on suppressing P.gingivalis biofilm formation was evaluated by SEM,Live/Dead staining,crystal-violet(CV)staining assay,XTT assay,CFU counting.EPS measurement and RT-q PCR assay were used respectively to verify the effects on virulence expression.The biocompatibility of periodontal ligament stem cells(PDLSCs)in the presence of Est816 on titanium substrates was detected by CCK-8 assay.The effects of Est816 on the immune responses of PDLSCs triggered by P.gingivalis-induced inflammation were also studied by enzyme-linked immunosorbent assay(ELISA)and RT-q PCR.The effects of Est816 on peri-implantitis in beagle dogs were analyzed by clinical measurement,MicroCT,HE and Toloniumchloride staining.Results: Est816 at the activity of 9 U/ml exhibited prominent anti-biofilm effects against P.gingivalis and reduced the production of EPS secreted from its matrix(P < 0.01).Additionally,Est816 decreased the expression of the virulence factor genes,fim A,rgp A,and kgp.CCK-8 assay on PDLSCs demonstrated the high cell compatibility of Est816(≤9 U/ml)both in the short term(6-24 h),and in the long term(1-3 d).The secretion of IL-1β,IL-6 and TNF-α on PDLSCs stimulated by P.gingivalis was significantly inhibited by 9 U/ml of Est816(P < 0.05),as well as the gene expression of IL-8 depicted by RTq PCR.In in vivo model,radiographically bone loss observed at Est816-treated sites showed no statistically significant difference(p > 0.05)compared to non-treated ones.Meanwhile,Est816 effectively enhance the adhesion of osteocyte onto the surface of implant and abated the inflammation responses of the adjacent soft tissues.Conclusion: N-acyl homoserine lactonase Est816 significantly inhibited P.gingivalis biofilm formation and exhibited anti-peri-implantitis in dogs with well biocompatibility,suggesting Est816 would be a new adjunctive treatment for peri-implantitis. |
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