The therapeutic potential of Osmundacetone for rheumatoid arthritis: Effects and mechanisms on osteoclastogenesis.

The present study aimed to investigate the therapeutic potential of Osmundacetone (Osu), a natural plant product, for the treatment of rheumatoid arthritis (RA). The study revealed that Osu effectively reduced arthritis-induced swelling and bone destruction, as well as alleviating inflammation-related factors and oxidative stress in animal models. We focused the mechanism exploration on its regulatory mechanism on osteoclastogenesis in the next investigation. In vitro experiments demonstrated a dose-dependent inhibition of osteoclastic differentiation by Osu, as evidenced by tartrate resistant acid phosphatase (TRAP) staining and a reduction in osteoclastic differentiation markers observed through Western blotting analysis. And three different approaches Osu inhibiting osteoclastogenesis were found in our researches: (1) The binding of Receptor Activator of Nuclear Factor Kappa B (RANK) and Osu was revealed by the in-silico analysis. (2) According to 2,7-Dichlorodihydrofluorescein diacetate (DCFH-DA) staining, Osu attenuated the level of reactive oxygen species (ROS), and western blotting studies revealed this effect was modulated by the regulation of Kelch-like ECH-associated protein 1/Nuclear Factor erythroid 2-Related Factor 2 (Keap1/Nrf2) pathway. (3) Interestingly, we found that Osu increased the lipid peroxidation via downregulating the expression of glutathione peroxidase 4 (GPX4) at the same time as reducing the ROS, leading to the reduction of the fluidity of the membrane and the fusion of osteoclasts which could be reversed by using the ferroptosis inhibitor- Ferrostatin-1 (Fer-1). Overall, a natural compound to the existing therapeutics for rheumatoid arthritis was confirmed and a new strategy for inhibiting osteoclastogenesis was added.