Fuhu Lijie Tang treats rheumatoid arthritis through multitarget therapy from autoantigen formation to bone destruction.

[BACKGROUND] Rheumatoid arthritis (RA) is an incurable, disabling autoimmune disease, and combination therapy with disease-modifying antirheumatic drugs targeting different pathological mechanisms is a therapeutic strategy to improve treatment outcomes. Traditional Chinese medicine (TCM) offers the advantage of multi-component, multi-target therapy for RA; however, its ability to simultaneously target multiple key pathological mechanisms of RA remains to be further investigated. Fuhu Lijie Tang (FHLJT) is a novel TCM formulation with potential therapeutic effects on RA, and its anti-arthritic mechanisms require systematic study.

[OBJECTIVE] This study aimed to comprehensively investigate the anti-arthritic effects of FHLJT and its underlying molecular mechanisms, focusing on its potential to simultaneously target multiple key pathological mechanisms in the treatment of RA.

[METHODS] Collagen II-induced arthritic (CIA) rats received FHLJT treatment, with therapeutic effects assessed through arthritis scoring, paw swelling measurement, inflammatory marker analysis, and histopathology. Synovial tissue transcriptomics identified differentially expressed genes, followed by validation through Western blot, immunohistochemistry, ELISA, and flow cytometry to validate these findings.

[RESULTS] FHLJT significantly reduced joint inflammation and histopathological damage in CIA rats. Transcriptomic analyses showed that FHLJT downregulated multiple RA-associated pathways, including RA signaling, T cell receptor (TCR), B cell receptor (BCR), vascular endothelial growth factor, osteoclast differentiation, antigen presentation, phagosome, and protein modification pathways. Further interaction analysis identified the phosphoinositide 3-kinase (PI3K) - protein kinase B (Akt) and AMP-activated protein kinase (AMPK) signaling pathways as central to these processes. Experimental validation confirmed that FHLJT inhibited citrullinated proteins, peptidyl arginine deiminase 2 (PADI2), PADI4, interferon gamma inducible protein 30, and CD74 expression in joint tissues of CIA rats. It also suppressed phosphorylated zeta chain of T cell receptor associated protein kinase 70 (p-ZAP70)/ZAP70, inducible T cell costimulator, programmed cell death protein 1 (PD-1), interleukin-17 levels in the TCR pathway, and reduced phosphorylated tyrosine-protein kinase Lyn (p-LYN)/LYN, phosphorylated Ras-related C3 botulinum toxin substrate (p-Rac)/Rac, and anti-type II collagen antibody levels in the BCR pathway. Additionally, FHLJT decreased synovial fibroblast marker CD90 and angiogenesis proteins, and inhibited osteoclast markers. In vitro, FHLJT inhibited M1 macrophage differentiation and MHC II expression while promoting M2 differentiation.

[CONCLUSION] FHLJT exerts its therapeutic effects by simultaneously targeting multiple key pathological mechanisms of RA through 74 compounds (e.g., sinomenine) which modulate processes such as citrullinated protein production, antigen presentation, TCR and BCR signaling pathways, synovial hyperplasia, angiogenesis, osteoclast differentiation, and the PI3K-Akt and AMPK signaling pathways.