Folium Hibisci Mutabilis extract suppresses M1 macrophage polarization through mitochondrial function enhancement in murine acute gouty arthritis.

Background: Acute gout arthritis (AGA) is a common metabolic joint disease and urgently needs a safer alternative therapy due to the significant side effects from long-term use of primary medications. Folium Hibisci Mutabilis, a traditional medicinal herb, has demonstrated promising therapeutic efficacy in the clinical management of AGA, but its pharmacological mechanisms remain to be elucidated.

Methods: Folium Hibisci Mutabili was isolated and refined into the Folium Hibisci Mutabilis Extract (FHME). Then, monosodium urate-induced AGA animal models were applied to identify the anti-inflammatory and analgesic effects of FHME in vivo through various techniques, including ultrasonography, Paw withdrawal thresholds, histological staining, etc. We used RNA-seq, qRT-PCR, ELISA, and flow cytometry to evaluate the efficacy of FHME on M1 polarization. Utilizing transmission electron microscope and oxygen consumption rate examinations in conjunction with Mito-Tracker staining, we observed the effects of FHME on mitochondrial morphology and function. Finally, we employed proteomics analysis, siRNA, qRT-PCR, western blot and other techniques to investigate the underlying mechanism of FHME's actions between the two phenotypes and the key targets.

Results: We observed a notable reduction in inflammation and pain, as well as the decreased infiltration of inflammatory cells and expression of IL-1β in synovial tissue of AGA mice upon treatment with FHME. FHME suppressed TNF-α, IL-1β, iNOS, and IL-18 expression in BMDM-derived macrophages and inhibited the formation of F4/80CD86 cells. Mechanically, FHME protected mitochondrial morphology and stimulated the expression of key oxidative phosphorylation proteins, such as Ubiquinol Cytochrome c Reductase Core Protein I (UQCRC1), UQCRC2, CYCS, and NDUFA4. Additionally, it enhanced the activity of respiratory complex III, recovered cellular aerobic respiration under LPS and MSU induction. FHME lost its effect to downregulate M1 macrophage polarization with the presence of rotenone or si-UQCRC1. Finally, 10 compounds were identified from FHME having potential binding affinity with the UQCRC1 protein.

Conclusions: The therapeutic potential of FHME for AGA is associated with the maintenance of mitochondrial function to inhibit M1 macrophage polarization, which is intimately linked to the UQCRC1. Our findings highlight the potential of Folium Hibisci Mutabilis as a safe and effective approach for AGA.