Treatment with Melittin Induces Apoptosis and Autophagy of Fibroblast-like Synoviocytes in Patients with Rheumatoid Arthritis

Background: Melittin, the major medicinal component of honeybee venom, exerts antiinflammatory, analgesic, and anti-arthritic effects in patients with Rheumatoid Arthritis (RA). RA is an inflammatory autoimmune joint disease that leads to irreversible joint destruction and functional loss. Fibroblast-Like Synoviocytes (FLS) are dominant, special mesenchymal cells characterized by the structure of the synovial intima, playing a crucial role in both the initiation and progression of RA. Objective: In this study, we evaluated the effects of melittin on the viability and apoptosis of FLS isolated from patients with RA. Methods: Cell viability was determined using CCK-8 assays; apoptosis was evaluated by flow cytometry, and the expression levels of apoptosis-related proteins (caspase-3, caspase-9, BAX, and Bcl-2) were also determined. To explore whether melittin alters inflammatory processes in RA-FLS, IL-1β levels were determined using an enzyme-linked immunosorbent assay (ELISA). Furthermore, we performed GFP-LC3 punctate fluorescence dot assays and western blotting (for LC3, ATG5, p62, and Beclin 1) to assess autophagy in RA-FLS. Results: Our results show that melittin can significantly impair viability, promote apoptosis and autophagy, and inhibit IL-1β secretion in RA-FLS. Conclusion: Melittin may be useful in preventing damage to the joints during accidental local stimulation.