Nobiletin ameliorates rheumatoid arthritis inflammation via suppression of the IL-17/NF-κB/MMP9 pathway.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovial proliferation and inflammatory infiltration. Nobiletin (NOB), a citrus-derived flavonoid, exhibits diverse pharmacological activities including anti-inflammatory and anti-cancer effects. Nevertheless, its therapeutic potential and mechanisms in RA remain largely unexplored. This study aimed to explore the potential targets and molecular mechanisms of NOB in the treatment of RA. We evaluated the effects of NOB on joint swelling and pathology in CIA mice, and assessed its impact on the proliferation, migration, apoptosis, and inflammatory factor expression of RA-FLS. Network pharmacology and molecular docking analyses suggested favorable binding affinity of NOB to key proteins. Finally, RA-FLS were treated with recombinant IL-17A protein to observe the reversing effects of NOB on cell phenotype and signaling pathways. In the CIA mouse model, NOB reduced paw swelling and suppressed synovial hyperplasia and inflammatory responses, accompanied by decreased expression of TNF-α, IL-1β, and MMP9. In RA-FLS cells, NOB suppressed proliferation and migration, induced arrest at the G2/M phase, and promoted apoptosis via upregulation of Bax/Caspase-3 and downregulation of Bcl-2. It also modulated cytokine expression by increasing the levels of IL-4 and IL-10 while decreasing those of IL-6, IL-17, MMP1, and MMP3. Mechanistically, network pharmacology and Western blotting validation suggested that NOB may act through the IL-17/NF-κB/MMP9 axis, inhibiting IL-17A, TRAF6, p-p65, and MMP9 in a concentration-dependent manner. This effect was partially counteracted by IL-17A recombinant protein, thereby supporting the potential involvement of this pathway in NOB's effects. In conclusion, NOB alleviates the inflammatory pathological response in CIA mice and improved the phenotypic alterations of RA-FLS cells. These therapeutic effects may be mediated, at least in part, through the modulation of the IL-17/NF-κB/MMP9 signaling pathway. Collectively, our findings provide a theoretical basis for further investigation of NOB as a potential therapeutic agent for RA.