NaRu-3 ameliorates experimental rheumatoid arthritis via MAPK pathway inhibition

NaRu-3 is a traditional Mongolian multi-component formula widely used for rheumatoid arthritis (RA), but its pharmacological mechanism remains unclear.

To elucidate the molecular basis of NaRu-3 against RA.

Major bioactive constituents of NaRu-3 were characterized by chemical fingerprinting. Therapeutic efficacy was evaluated in collagen-induced arthritis mice using clinical scores and [¹⁸F]FDG PET/CT to quantify inflammatory activity in the joints. Cytokine assays together with hepatic and renal histopathology, were assessed to evaluate the safety of NaRu-3. Transcriptomic profiling of ankle tissue was performed to identify key pathways, followed by functional and protein validation in lipopolysaccharide-stimulated MH7A synoviocytes and HUVECs.

Eighty-seven compounds were identified. NaRu-3 significantly alleviated arthritis severity and reduced SUVmax, and decreased the serum TNF-α, IL-1β, IL-6, and VEGF-A levels. Histological analyses revealed diminished synovial hyperplasia and cartilage erosion, increased COL-2 deposition in cartilage, and reduced IL-6, TNF-α, and VEGF expression in synovial tissue without evident hepato- or nephrotoxicity. Transcriptomic analysis revealed coordinated regulation of extracellular matrix remodeling and inflammation, with significant enrichment of the MAPK pathway. HMGB1, ERK, p38, COX-2 and MMP-3 were markedly downregulated. In vitro, NaRu-3 inhibited proliferation, migration and angiogenic activity of synoviocytes and endothelial cells.

NaRu-3 attenuates experimental arthritis by suppressing MAPK-mediated inflammatory and matrix-remodeling signaling, thereby inhibiting synovial hyperplasia, angiogenesis, and cartilage damage. These findings provide mechanistic support for NaRu-3 as a promising multi-target therapeutic candidate to treat RA.