(D-Ala²)GIP Inhibits TNF-α-Induced Osteoclast Formation and Bone Resorption, and Orthodontic Tooth Movement.

Area of Science:

• Endocrinology
• Orthodontics
• Bone Biology

Background:

• Glucose-dependent insulinotropic polypeptide (GIP) influences bone remodeling.
• Dipeptidyl peptidase-4 (DPP-4) rapidly degrades native GIP.
• Tumor necrosis factor-alpha (TNF-α) drives osteoclastogenesis and is implicated in orthodontic tooth movement (OTM).

Purpose of the Study:

• To investigate the therapeutic potential of (D-Ala²)GIP, a DPP-4 resistant GIP analog.
• To assess the impact of (D-Ala²)GIP on TNF-α-induced osteoclastogenesis and bone resorption in vivo.
• To evaluate the effect of (D-Ala²)GIP on orthodontic tooth movement and associated root resorption.

Main Methods:

• Mice received daily supracalvarial injections of TNF-α with or without (D-Ala²)GIP.
• Orthodontic tooth movement was induced using a nickel-titanium spring in mice treated with (D-Ala²)GIP or PBS.
• Osteoclast formation, bone resorption, and tooth movement were quantified.

Main Results:

• (D-Ala²)GIP treatment significantly reduced TNF-α-induced osteoclast formation and bone resorption.
• Expression of osteoclastic markers TRAP and cathepsin K was decreased by (D-Ala²)GIP.
• (D-Ala²)GIP administration led to significantly reduced orthodontic tooth movement and fewer osteoclasts/odontoclasts.

Conclusions:

• (D-Ala²)GIP demonstrates potent inhibitory effects on osteoclastogenesis and bone resorption.
• This GIP analog effectively suppresses TNF-α-mediated bone loss.
• (D-Ala²)GIP shows promise in mitigating orthodontic tooth movement and root resorption.