The NLRP3 Inflammasome Regulates Orthodontic Tooth Movement

The NLRP3 inflammasome is a damage sensor driving pyroptotic cell death during orthodontic tooth movement (OTM). Recent studies have revealed impaired one-week OTM in mice lacking NLRP3. However, the relevance of NLRP3 during long-term OTM remains unknown.

OTM was analysed after 7, 14 and 21 days of force application in mice lacking NLRP3 (NLRP3^-/-), wild-type (WT) male and female littermates. Micro-computed tomography (μCT) was used to assess molar movement and bone quality. Tartrate-resistant acid phosphatase (TRAP) staining was used to visualise osteoclastic activity.

We show here that after 2 weeks of force application, OTM was delayed in mice lacking NLRP3 compared to WT mice. Interestingly, OTM regained speed in NLRP3^-/- mice catching up with the WT controls at day 21. Independent of NLRP3 expression, OTM caused alveolar bone loss compared to the untreated contralateral side. NLRP3^-/- mice showed a diminished number of TRAP-positive osteoclasts than WT male mice 14 and 21 days after OTM induction.

The results of this study suggest that NLRP3 is relevant during the early but not later stages of OTM.