IADR Abstract Archives
The Unrecognized Mechanism of B-Cells Activation in Response to Orthodontic Forces
Objectives: Orthodontic-tooth-movement (OTM) is achieved by bone-remodeling(BR) mediated via an aseptic-inflammatory process. B-cells, which play a crucial role in the etiology of inflammatory bone-diseases, are activated by antigen-recognition. Yet, whether mechanical-forces can activate B-cells remains unknown. Here, we aim to investigate the role of B-cells and their mechanism-of-action(MOA) in OTM.
Methods: NiTi-springs ligated between maxillary-first-molars(M1) and incisors in CD19cre homozygote and WT (C57BL/6) mice, generating mesial movement of M1. To study whether force application activates B-cells, total RNAs were extracted from dissected tissue blocks after 1,3,7 and 14 days, and exclusive B-cells genes were measured by qRT-PCR and immunofluorescence(IF) staining. OTM-distance and bone parameters were measured by μCT and histological-staining.To investigate B-cells' MOA, RNA-sequencing was performed after 3 days of OTM, and validated by qRT-PCR. Additionally, an OTM re-activation model was established to study whether B-cells can be primed in response to orthodontic-reactivation-forces .
Results: B-cells genes expression (CD19, B220 and CD79a) peaked at day 3 following OTM. IF demonstrated CD19+ B-cells in the alveolar bone, which were clustered in the compressed PDL at day 14. After 14 days, OTM rate was significantly decreased in CD19cre mice compare to WT control with significant reduction in osteoclasts number and bone formation process. RNA sequencing revealed 272 differentially expressed genes in CD19cre mice following 3 days, exhibited a distinct downregulation of genes associated with bone formation(Amelx), pro-inflammatory chemokines which promote bone resorption(Cxcl 2/3/5,Ccr6), B-cells homing chemokine(Cxcl13) and genes associated with negative regulation of bone formation (Bglap/2/3). In the re-activation OTM, acceleration of the OTM-rate was significantly impaired in the CD19cre mice compared to the WT mice.
Conclusions: This study demonstrates a previously unrecognized mechanism that B cells are activated in response to orthodontic-forces and required for BR and OTM via their CD19 receptor activation followed by unique cytokines/chemokines expression. Moreover, we highlighted the possibility of B-cells priming due to mechanical-forces which emphasis the adaptive immunity contribution in OTM.
Methods: NiTi-springs ligated between maxillary-first-molars(M1) and incisors in CD19cre homozygote and WT (C57BL/6) mice, generating mesial movement of M1. To study whether force application activates B-cells, total RNAs were extracted from dissected tissue blocks after 1,3,7 and 14 days, and exclusive B-cells genes were measured by qRT-PCR and immunofluorescence(IF) staining. OTM-distance and bone parameters were measured by μCT and histological-staining.To investigate B-cells' MOA, RNA-sequencing was performed after 3 days of OTM, and validated by qRT-PCR. Additionally, an OTM re-activation model was established to study whether B-cells can be primed in response to orthodontic-reactivation-forces .
Results: B-cells genes expression (CD19, B220 and CD79a) peaked at day 3 following OTM. IF demonstrated CD19+ B-cells in the alveolar bone, which were clustered in the compressed PDL at day 14. After 14 days, OTM rate was significantly decreased in CD19cre mice compare to WT control with significant reduction in osteoclasts number and bone formation process. RNA sequencing revealed 272 differentially expressed genes in CD19cre mice following 3 days, exhibited a distinct downregulation of genes associated with bone formation(Amelx), pro-inflammatory chemokines which promote bone resorption(Cxcl 2/3/5,Ccr6), B-cells homing chemokine(Cxcl13) and genes associated with negative regulation of bone formation (Bglap/2/3). In the re-activation OTM, acceleration of the OTM-rate was significantly impaired in the CD19cre mice compared to the WT mice.
Conclusions: This study demonstrates a previously unrecognized mechanism that B cells are activated in response to orthodontic-forces and required for BR and OTM via their CD19 receptor activation followed by unique cytokines/chemokines expression. Moreover, we highlighted the possibility of B-cells priming due to mechanical-forces which emphasis the adaptive immunity contribution in OTM.