Metabolomics and network pharmacology revealing the transdermal moxibustion compounds and their therapeutic mechanisms for rheumatoid arthritis

Background/purpose: Moxibustion, a traditional therapy employing the combustion of Artemisia argyi, exerts notable clinical benefits in rheumatoid arthritis (RA). However, the identity of the transdermal moxibustion compounds (TMOCs) and their molecular mechanisms of action remain poorly understood. This study sought to define the core TMOCs and delineate their therapeutic mechanisms in RA.

Study design/method: GC-MS was used to extract the relative concentrations of TMOCs in the subcutaneous tissue, which were incorporated into the network pharmacology to identify the center targets of primary TMOCs for RA. Meanwhile, the subcutaneous concentrations of TMOCs associated with the identified primary targets were quantified using GC-MS and standards. TMOCs-target interactions were examined via molecular docking and molecular dynamics simulation. Primary RA-derived fibroblast-like synoviocytes (RA-FLS) were isolated to evaluate biological effects of the core TMOCs using EdU proliferation assays, immunofluorescence, real-time Cell Analysis (RTCA), ELISA, qPCR, and Western blotting. In vivo efficacy was confirmed in the adjuvant-induced arthritis (AIA) rat model.

Results: A total of 54 TMOCs were identified, among which 16 were predicted to possess anti-RA activity. Network pharmacology indicated that essential TMOCs may mitigate RA by regulating inflammation and cellular proliferation, where TNF-α serves as a centered target. In addition, Citral, α-Terpineol and Borneol are the TMOCs stably interacting with TNF-α. In vitro, Citral inhibits the proliferation of RA-FLS, reduces the secretion of TNF-α and COX-2, and downregulates the protein expression levels of ERK1/2, p38 and c-Jun in RA-FLS. Meanwhile, α-Terpineol and Borneol inhibit RA-FLS invasion and modulate the mRNA expression levels of MMP-1 and MMP-2. In vivo, local administration of Citral to the plantar subcutaneous tissue ameliorated arthritic symptoms in AIA rats.

Conclusion: This study identified three promising TMOCs, Citral, α-Terpineol and Borneol, which target TNF-α to attenuate RA. Citral suppresses synovial proliferation and inflammation via MAPK pathway inhibition, while α-terpineol/borneol modulate MMP-mediated invasion.

Artemisia argyi; Borneol; Citral; Rheumatoid arthritis; TNF-α; α-terpineol.