(5R)-5-hydroxytriptolide inhibits proliferation, invasion, and migration of rheumatoid arthritis fibroblast-like synoviocytes through MIF-CD74 signaling pathway.

BACKGROUND

(5R)-5-Hydroxytriptolide (LLDT-8, T8), a derivative of triptolide, has been demonstrated to significantly inhibit the proliferation, invasion, and cytokine production of rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS), but its molecular targets remain unclear.

METHODS

By integrating 4D-DIA quantitative proteomics with single-cell transcriptomic profiling, we systematically identified differentially expressed proteins in RA-FLS. Subsequent functional validation, including pharmacological inhibition assays and multi-omics correlation analysis (transwell migration, western blot, and qRT-PCR), demonstrated that CD74 serves as a critical downstream target of T8, modulating the JNK-c-Jun signaling cascade.

RESULTS

CD74 was identified as aberrantly overexpressed in RA-FLS. T8 (50 nM) potently suppressed CD74 expression, concomitant with reduced RA-FLS proliferation, invasion, migration and cytokine production. Mechanistically, T8 disrupted JNK and c-Jun phosphorylation, establishing a CD74-JNK-c-Jun regulatory axis. These findings reveal T8's novel therapeutic potential through CD74 modulation and provide mechanistic insights into RA treatment.