Effect of lutein on improving traumatic temporomandibular joint fibrous ankylosis

This study investigated the therapeutic effects and potential mechanisms of lutein on traumatic temporomandibular joint (TMJ) fibrous ankylosis. A TMJ fibrous ankylosis model was established in rabbits, then randomly divided into a lutein-treated group and a model group (n = 8 per group), followed by daily oral administration of lutein (10 mg/kg) or saline for 4 weeks. Compared with the model group, the lutein group showed significantly higher body weight (P = 0.049), maximum mouth opening (P = 0.043), condylar surface area (P = 0.001), and condylar volume (P = 0.003). Haematoxylin and eosin staining demonstrated a thicker fibrous layer, active cellular proliferation, and more distinct cell layers in the lutein group. Transmission electron microscopy showed reduced fibrous proliferation and increased collagen fibre diameter in the articular disc of the lutein group compared to the model group. EdU (5-ethynyl 2-deoxyuridine) staining indicated a significant increase in cell proliferation in the lutein group. Enzyme-linked immunosorbent assay revealed higher serum levels of osteocalcin (OCN), N-terminal propeptide of type I procollagen (PINP), and bone-specific alkaline phosphatase (BALP), alongside reduced C-terminal cross-linking telopeptide of type I collagen (β-CTx) in the lutein group. Real-time quantitative reverse transcription-polymerase chain reaction analysis showed up-regulated expression of ALP, OCN, type I collagen (COLIA1), and osteopontin (OPN) in the lutein group compared to the model group. Lutein effectively mitigates fibrochondral formation and improves TMJ function in a rabbit model of TMJ fibrous ankylosis, suggesting its potential as a therapeutic agent for traumatic joint disorders.