Compressive Stress and Inflammation Induce Ferroptosis in Periodontal Ligament Cells Through ACSL4 Activation in Orthodontically Induced Inflammatory Root Resorption

ABSTRACT Objectives Orthodontically induced inflammatory root resorption (OIIRR) is an inflammation induced by excessive orthodontic force in the periodontium. The aim of this study was to identify the role of ferroptosis in periodontal ligament cells in OIIRR and its underlying mechanism. Materials and Methods Human periodontal ligament cells (hPDLCs) were subjected to 2 g/cm 2 of compressive stress along with 20 ng/mL of interleukin‐1β (IL‐1β) stimulation for 24 h. The occurrence of ferroptosis in hPDLCs is detected by Western blot analysis and ferroptosis‐related kits. For in vivo analyses, a mouse OIIRR model was established, and the ACSL4 inhibitor (Rosiglitazone, Rosi) was administered intraperitoneally. Micro‐CT was employed to evaluate the occurrence of OIIRR, and immunohistochemical staining (IHC) was performed to detect changes in ferroptosis‐related markers. Results Upon applying compressive stress and IL‐1β stimulation to hPDLCs, Western blot analysis showed an upregulation of the ferroptosis marker ACSL4 and a downregulation of GPX4, along with significant increases in ROS, MDA and Fe 2+ levels, indicating enhanced ferroptosis. However, when hPDLCs were treated with Rosi (1 μM), ferroptosis was alleviated. Micro‐CT analysis showed that root resorption volume decreased after Rosi application. Additionally, Ferroptosis‐related markers changed significantly in the PDLCs in mice via IHC staining. Conclusions ACSL4‐mediated ferroptosis, triggered by compressive stress and inflammation in hPDLCs, contributed to the development of OIIRR. Rosi has been shown to inhibit OIIRR and serve as a novel therapeutic target for OIIRR treatment.