miR-655-3p is a highly accurate diagnostic biomarker for primary osteoarthritis and alleviates joint inflammation by targeting TLR4

Objective: This study aimed to evaluate the potential of miR-655-3p as a diagnostic biomarker for primary osteoarthritis (OA) and to investigate its intrinsic molecular mechanisms as a means of addressing the lack of sensitive early diagnostic biomarkers and targeted anti-inflammatory therapies for this prevalent degenerative joint disorder.

Methods: Quantitative real-time polymerase chain reaction was performed to measure (1) miR-655-3p levels in the serum of 93 primary OA patients and 60 non-OA controls, (2) miR-655-3p levels in the synovial fluid of OA patients, and (3) messenger RNA (mRNA) expression of TLR4, RelA, TNF-α, and IL-6 in the IL-1β–induced OA chondrocyte model. Enzyme-linked immunosorbent assay measured the secretion of IL-6 and TNF-α. Receiver operating characteristic curve (ROC) analysis assessed its diagnostic value in multiple clinical scenarios. Cell function assays investigated cell viability and apoptosis. Target genes were predicted via 3 databases, and the interaction between miR-655-3p and TLR4 was verified by dual-luciferase reporter assay and Western blot. Rescue experiments were performed to confirm the mechanistic specificity.

Results: miR-655-3p was downregulated by 44.8% in OA serum (P < .001) and 46.7% in IL-1β–induced chondrocytes (P < .001). ROC curve analysis showed an overall area under the curve (AUC) of 0.9518 (95% CI: 0.920-0.983), with consistent high accuracy in distinguishing OA from healthy controls (AUC = 0.9509), meniscus injury patients (AUC = 0.9425), and mild OA from controls (AUC = 0.9306). Serum miR- 655-3p levels were negatively correlated with OA severity (American Academy of Orthopaedic Surgeons score, P = .010) and inflammatory factor levels (TNF-α, IL-6, both P < .001). Dual-luciferase assay confirmed TLR4 as a direct target of miR-655-3p; miR 655-3p overexpression reduced TLR4 protein expression by 48.7%, while inhibition increased it by 52.8%. TLR4 overexpression completely reversed the antiinflammatory and anti-apoptotic effects of miR-655-3p in OA chondrocytes.

Conclusion: miR-655-3p is a highly accurate diagnostic biomarker for primary OA, and upregulating miR-655-3p may provide a novel clinical treatment direction by targeting TLR4 to alleviate joint inflammation.

Cite this article as: Li R, Chen C, Chen D. MiR-655-3p is a highly accurate diagnostic biomarker for primary osteoarthritis and alleviates joint inflammation by targeting TLR4. Acta Orthop Traumatol Turc., 2026; 60(4), 0803, doi: 10.5152/j.aott.2026.25803.