IADR Abstract Archives

The Role of Immune Cells in Orthodontic Tooth Movement

Objective: Orthodontic-tooth-movement (OTM) is an inflammation-based-process (sterile) in which immune-cells are involved, however, little is known about their type and function in this process. NK and CD4+-T-cells (NKs;CD4+-Ts) are major secretors of TNFα and IFNγ-cytokines, which were shown to promote differentiation of Monocytes into Osteoclasts and activation of Osteoclasts which enable OTM through bone-resorption. The main activating-receptors of mice's-NKs are Ncr1 and NKG2D. We aimed to investigate the direct in-vivo role of NKs, their Ncr1 and NKG2D-receptors, CD4+-Ts and the secreted-cytokines in OTM.

Method: Ni-Ti closed-coil-springs were set between upper-left-first-molar (M1) and upper-incisors of C57BL/6-mice in wild-type (WT) control-group and 8 experimental-groups (n=10/group) for 12 days:  NKs-depleted (NKs.dep), Ncr1-knockout (the Ncr1-gene was replaced by GFP [Ncr1gfp/gfp]), Ncr1-heterozygote (Ncr1+/gfp), NKG2D-blocked in WT-mice (WT/NKG2D.bl), NKG2D-blocked in Ncr1gfp/gfp-mice (Ncr1gfp/gfp/NKG2D.bl), CD4+-Ts–depleted (CD4+-Ts.dep), TNFα-knockout (TNFα-/-) and IFNγ-knockout (IFNγ-/-). A split-mouth-technique was used, in which M1-M2 distance was measured using μCT-scanner. Mice's maxillae were prepared for histology. The in-vivo accumulation of NKs in the periodontal-ligament (PDL) could be evaluated with the GFP presence in Ncr1gfp/gfp and Ncr1+/gfpmice. NKs' and Osteoclasts' number and location were evaluated using immunofluorescence and TRAP-stainings.  

Result: OTM was significantly reduced in NKs.dep, Ncr1gfp/gfp, Ncr1gfp/gfp/NKG2D.bl, CD4+-Ts.dep, TNFα-/- and IFNγ-/- groups (x1.49;x1.22;x4.31;x1.18;x3.30;x2.25 fold change, respectively, p<0.05), compared to WT, but was not changed in Ncr1+/gfp or WT/NKG2D.bl. The number of GFP-labeled-NKs significantly increased in PDL of treated-teeth in comparison to contralateral side (x3.44, p<0.05). Osteoclasts number correlated with the M1-M2 distance in all groups (p<0.05).

Conclusion: OTM process in mice is mediated through Ncr1 and NKG2D receptors in NKs. Absence of NKs, Ncr1 and NKG2D-receptors, CD4+-Ts, TNFα and IFNγ significantly reduced the OTM-rate. NKs are accumulating in the PDL in response to orthodontic-force. Understanding the immune mechanisms involved in OTM will contribute to find novel therapeutic means to clinically control it.

Pan European Region Meeting
2014 Pan European Region Meeting (Dubrovnik, Croatia)
Dubrovnik, Croatia
2014
83
Scientific Groups
  • Fleissig, Omer  ( Hebrew University- Hadassah School of Dental Medicine, Jerusalem, , Israel )
  • Glassner, Ariella  ( Lautenberg Center for General and Tumor Immunology, Hebrew University, Jerusalem, , Israel )
  • Enk, Jonatan  ( Lautenberg Center for General and Tumor Immunology, Hebrew University, Jerusalem, , Israel )
  • Mandelboim, Ofer  ( Lautenberg Center for General and Tumor Immunology, Hebrew University, Jerusalem, , Israel )
  • Chaushu, Stella  ( Hebrew University- Hadassah School of Dental Medicine, Jerusalem, , Israel )
    • Oral Session
    Microbiology/Immunology II
    09/11/2014