人牙周韧带成纤维细胞来源外泌体miR-155-5p通过诱导破骨细胞分化促进正畸牙移动OA

Objective:To investigate whether exosomes derived from human periodontal ligament fibro-blasts(hPDLFs)under orthodontic force regulate osteoclast differentiation via their carried miR-155-5p,thereby influencing orthodontic tooth movement(OTM).Methods:hPDLFs were cultured in vitro and divid-ed into a control group(CON)and a force-stimulated group(Force).The force group was subjected to a continuous load of 2g/cm2 via a glass disc for 48 hours to simulate orthodontic force.Exosomes were extracted from the cell culture supernatant using ultracentrifugation and identified by transmission electron microscopy(TEM),nanoparticle tracking analysis(NTA),and Western Blot detection of exosomal marker proteins(TSG101,CD9,CD81).miRNA sequencing and qRT-PCR were used to screen and validate differentially expressed miRNAs in the exosomes.Furthermore,a rat OTM model was established.Thirty-two male Sprague-Dawley(SD)rats were randomly divided into Sham,OTM,OTM+Force-Exo,and OTM+AntagomiR-155-5p-Exo groups.Exosomes interventions were administered via local injection and tail vein injection.Mi-cro-CT scanning was used to measure the orthodontic tooth movement distance and quantitatively analyze pa-rameters such as bone mineral density(BMD),bone volume/tissue volume(BV/TV),trabecular thickness(Tb.Th),and trabecular separation(Tb.Sp).Histological analysis was performed using H&E staining and TRAP staining.The expression levels of key osteoclast marker genes(nuclear factor of activated T-cells,cy-toplasmic 1(NFATc1),Fos proto-oncogene(c-Fos),calcitonin receptor(CTR),and cathepsin K(CTSK))were detected by qRT-PCR and Western Blot.Results:Mechanical force stimulation significantly upregulated the expression of miR-155-5p in exosomes derived from hPDLFs(P<0.01).Compared to the OTM group,the OTM+Force-Exo group showed a significant increase in orthodontic tooth movement distance(P<0.01),accompanied by decreased BMD,BV/TV and Tb.Th,as well as increased Tb.Sp(P<0.01).Histological staining revealed a significant increase in the number of TRAP-positive cells on the pressure side(P<0.01)and exacerbated bone resorption in this group.In contrast,the changes in all indicators in the OTM+AntagomiR-155-5p-Exo group were significantly inhibited compared to the OTM+Force-Exo group(P<0.05,P<0.01).Conclusion:Under orthodontic forces,miR-155-5p is significantly upregulated in ex-osomes derived from hPDLFs.These miR-155-5p-enriched exosomes can promote alveolar bone resorption by inducing osteoclast differentiation,thereby accelerating OTM.