Opuntioside, opuntiol and its metallic nanoparticles attenuate adjuvant-induced arthritis: Novel suppressors of Toll-like receptors -2 and -4

Rheumatoid arthritis (RA) is a chronic autoimmune disease of synovial inflammation and joint destruction. This study reports anti-arthritic potential of opuntioside-I opuntiol, and its gold and silver nanoparticles (NPs) against Complete Freund's Adjuvant (CFA)-induced arthritic rats. The mechanistic studies were performed targeting TLRs (TLR-2 and TLR-4) and cytokines (IL-1β and TNF-α) expressions to validate their anti-inflammatory and immuno-modulatory response. The nano-formulations were successfully characterized employing Atomic Force Microscopy (AFM) and Dynamic Light Scattering (DLS) analysis. Opuntiol and opuntioside (OP and OPG: 10, 50 and 100 mg/kg) and opuntiol-coated silver and gold NPs (OP-AgNPs and OP-AuNPs: 0.5, 1 and 3 mg/kg) treatments in arthritic rat have shown minimal arthritic score exhibiting mild to moderate articular changes and tissue swelling in ankle joints. Radiographic examination reveals significant reduction in synovitis with improvement in joints degenarative changes in the presence of aforementioned treatments. Likewise, histology of rat ankle joints depicted comparatively lesser influx of inflammatory cells and diminished granulamatous inflammation. Moreover, treatment groups suppressed protein and mRNA expressions of TLRs (TLR-2 and TLR-4) and cytokines (IL-1β and TNF-α) levels were also significantly declined in the presence of OPG, OP and its NPs comparing to arthritic control. This investigation concludes, the tested compounds and nano-formulations successfully restored the disease progression in CFA-induced arthritic rat owing to their immunomodulatory and anti-inflammatory potentials and can be considered for RA targeted therapy to address the utmost challenges of the disease.