Rheumatoid arthritis (RA) is a chronic autoimmune disorder with complex pathogenesis. Homalomena occulta (Lour.) Schott, a traditional Chinese medicine, has been used for RA treatment, but its systematic molecular mechanisms remain unclear. This study aims to explore the therapeutic targets and mechanisms of H. occulta for RA using an integrated approach.

Active compounds and targets of H. occulta were screened from the TCMSP database. RA-related differentially expressed genes (DEGs) were identified from the GEO dataset (GSE89408). Potential therapeutic targets were obtained by intersecting drug targets with RA-DEGs. Functional enrichment analysis was performed using GO and KEGG. Single-cell RNA sequencing (scRNA-seq) analysis of PBMCs and synovial tissue identified cell-type-specific target expression. Molecular docking simulations evaluated the binding of active metabolites to the key target Lysozyme (LYZ). In vivo validation was conducted in an adjuvant-induced arthritis (AIA) rat model, assessing clinical scores, histopathology, serum cytokines, and LYZ protein expression.

We identified 30 bioactive compounds in H. occulta and 30 potential anti-RA targets. Enrichment analysis revealed these targets were significantly involved in immune-inflammatory pathways (e.g., IL-17 signaling) and vascular processes. scRNA-seq analysis showed these targets were prominently expressed in monocytes/macrophages and T cells within RA synovial tissue. Molecular docking confirmed stable binding of key H. occulta metabolites ((-)-nopinene and m-Cymol) to LYZ. In vivo, H. occulta extract treatment significantly alleviated arthritis severity, reduced paw swelling and pathological joint damage, and decreased serum levels of TNF-α, IL-1β, IL-6, and IL-17A in AIA rats. Crucially, H. occulta extract dose-dependently suppressed the elevated expression of LYZ protein in synovial tissue.

This study demonstrates that H. occulta extract alleviates RA symptoms by targeting multiple pathways and cell types, with LYZ identified as a key target. The anti-RA effect is mediated through the suppression of pro-inflammatory cytokines and modulation of LYZ expression. Our findings provide a scientific basis for the clinical application of Homalomena occulta in RA treatment.