Protective effects of piperlongumine against adjuvant-induced arthritis in rats through modulating OPG/RANKL/NF-κB signaling pathway.

OBJECTIVES: We examined the antirheumatoid effects of piperlongumine (PLM) on rat adjuvant-induced arthritis (AIA) and explored the underlying mechanisms involved. METHODS: PLM (2.5, 5, and 10 mg/kg) was administered intraperitoneally to AIA rats to assess its effectiveness. Blood, thymus, spleen, ankle joint, and synovial tissue samples were gathered for subsequent analyses, like enzyme-linked immunosorbent assay, thymus/spleen index measurement, ankle joint pathological examination, immunohistochemistry assay, polymerase chain reaction, and western blot assay. Moreover, the involvement of osteoprotegerin (OPG)/receptor activators of nuclear factor κB ligand (RANKL)/nuclear factor-κB (NF-κB) signaling was investigated. KEY FINDINGS: PLM effectively relieved inflammation and joint destruction in AIA rats, as indicated by reductions in hind paw swelling, arthritis index, thymus/spleen index, ankle joint pathological damage, production of TNF-α, IL-1ß, and IL-6 in both serum and synovium, and osteoclast formation. Also, PLM treatment raised OPG production, reduced RANKL expression, and elevated the OPG/RANKL ratio in synovial tissues. Furthermore, PLM prevented IκBα degradation and phosphorylation, resulting in a reduced expression of the nuclear NF-κB p65 protein in AIA rat synovial tissues. CONCLUSIONS: PLM demonstrated strong antiarthritic effects in rats with AIA by influencing the OPG/RANKL/NF-κB signaling pathway, highlighting its potential clinical relevance in treating rheumatoid arthritis.

Novel HIF-1α Inhibitor AMSP-30m Mitigates the Pathogenic Cellular Behaviors of Hypoxia-Stimulated Fibroblast-Like Synoviocytes and Alleviates Collagen-Induced Arthritis in Rats via Inhibiting Sonic Hedgehog Pathway.

Synovial hypoxia-inducible factor 1α (HIF-1α) is a prospective therapeutic target for rheumatoid arthritis (RA). AMSP-30 m, a novel HIF-1α inhibitor, was reported to have notable anti-arthritic effects in rats with adjuvant-induced arthritis. However, its roles in inhibiting the pathogenic behaviors of fibroblast-like synoviocytes (FLS) and the involved mechanisms remain unknown. Here, AMSP-30 m inhibited proliferation and induced apoptosis in hypoxia-induced RA FLS (MH7A cell line), as evidenced by decreased cell viability, reduced Ki67-positive cells, G0/G1 phase arrest, lowered C-myc and Cyclin D1 protein levels, emergence of apoptotic nuclear fragmentation, raised apoptosis rates, and activation of caspase 3. Furthermore, AMSP-30 m prevented hypoxia-induced increases in pro-inflammatory factor production, MMP-2 activity, migration index, migrated/invasive cells, and actin cytoskeletal rearrangement. In vivo, AMSP-30 m alleviated the severity of rat collagen-induced arthritis (CIA). Mechanically, AMSP-30 m reduced HIF-1α expression and blocked sonic hedgehog (Shh) pathway activation in hypoxia-induced MH7A cells and CIA rat synovium, as shown by declines in pathway-related proteins (Shh, Smo, and Gli-1). Particularly, the combination of Shh pathway inhibitor cyclopamine enhanced AMSP-30 m's inhibitory effects on the pathogenic behaviors of hypoxia-stimulated MH7A cells, whereas the combination of Shh pathway activator SAG canceled AMSP-30 m's therapeutic effects in vitro and in CIA rats, implying a close involvement of Shh pathway inhibition in its anti-arthritic effects. We likewise confirmed AMSP-30 m's anti-proliferative role in hypoxia-induced primary CIA FLS. Totally, AMSP-30 m suppressed hypoxia-induced proliferation, inflammation, migration, and invasion of MH7A cells and ameliorated the severity of rat CIA via inhibiting Shh signaling.