Inhibition of NCOA4/FTH1-mediated ferritinophagy attenuates ferroptosis in PDLCs and alleviates orthodontically induced inflammatory root resorption
Liyan Liu, Dongyang Li, Zhe Zhou, Hong Ding, Runze Zhang, Xueyuan Han, Kexin Huang, Chunmiao Jiang
Abstract
BACKGROUND: Disruption of iron homeostasis is closely associated with ferroptosis and inflammation-related diseases. Nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy plays a central role in regulating intracellular iron levels and inducing ferroptosis. However, its involvement in orthodontically induced inflammatory root resorption (OIIRR) remains largely unexplored. METHODS : In vitro, a compressive force (CF) loading model was established using human periodontal ligament cells (hPDLCs). Western blotting and immunofluorescence staining were performed to detect the expression of ferroptosis-related proteins, including NCOA4, FTH1, and GPX4. Intracellular levels of malondialdehyde (MDA), Fe²⁺, and reactive oxygen species (ROS) were measured using a ferroptosis assay kit. JC-1 staining was used to evaluate mitochondrial membrane potential. NCOA4 was silenced via lentiviral transfection, and the small-molecule inhibitor 9a was used to further assess its functional role in ferroptosis. In vivo, an OIIRR mouse model was established. Hematoxylin and eosin (H&E) staining, tartrate-resistant acid phosphatase (TRAP) staining, and micro-computed tomography (micro-CT) were used to assess root resorption. The expression of NCOA4, FTH1, and GPX4 in periodontal tissues was evaluated via immunohistochemistry and immunofluorescence. Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, was administered intraperitoneally to investigate its therapeutic effect on OIIRR. RESULTS: CF and IL-1β stimulation induced ferroptosis in hPDLCs, as indicated by increased intracellular Fe²⁺, ROS, and MDA levels, decreased GPX4 expression, and mitochondrial damage. NCOA4 expression was markedly upregulated in both in vitro and in vivo models, leading to ferritin degradation and iron overload. Fer-1 treatment effectively reduced oxidative stress and iron accumulation in vitro and alleviated OIIRR in vivo. Compound 9a suppressed NCOA4 expression and mitigated ferritinophagy-mediated ferroptosis. CONCLUSIONS: NCOA4/FTH1-mediated ferritinophagy promotes ferroptosis under compressive and inflammatory conditions, contributing to OIIRR pathogenesis. Targeting the NCOA4/FTH1 axis may represent a promising therapeutic strategy for preventing orthodontically induced root resorption.