Cimiracemate A confers protection on arthritic neonatal rats via regulation of iNOS/NF-κB/TLR-4 pathway

Purpose: To investigate the protective effect of cimiracemate A on Freund’s adjuvant-induced rheumatoid arthritis (RA) in neonatal rats, and the underlying mechanism. Methods: Rheumatoid arthritis was induced in rat pups using Complete Freund’s adjuvant (100 µg/100 µL/body weight) which was intra-dermally injected at the tail region. After 21 days of establishment of RA, the rats were randomly assigned to four groups of ten rats each: control group, RA group, 5 mg/kg cimiracemate A group, and 10 mg/kg cimiracemate A group. Cimiracemate A was orally administered for 45 days. The effect of cimiracemate A on oxidative stress biomarkers, superoxide dismutase (SOD), malondialdehyde (MDA) and reduced glutathione (GSH) were determined using standard methods. Plasma levels of the inflammatory cytokines interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE-2) and matrix metalloproteinase-3 (MMP-3) were determined using enzyme-linked immunosorbent assay (ELISA). Western blotting was used to determine the levels of protein expressions of iNOS, NF-κB and TLR-4. Results: The level of MDA significantly increased and the level of GSH significantly decreased in RA group relative to control group (p < 0.05) following treatment with cimiracemate A. SOD activity was significantly reduced in RA group, when compared with control group (p < 0.05). However, treatment with cimiracemate A significantly and dose-dependently reversed the altered levels of MDA and GSH and SOD activity, when compared with RA group (p < 0.05). Plasma levels of IL-1β, TNF-α, PGE-2 and MMP-3 were significantly higher in RA group than in control group, but were significantly and dosedependently reduced after treatment with cimiracemate A (p < 0.05). There were significant increases in the levels of expression of iNOS, NF-κB and TLR-4 proteins in the chondrocytes of RA group, relative to control group (p < 0.05). However, treatment with cimiracemate A significantly and dose-dependently down-regulated the expressions of these proteins, when compared with RA group (p < 0.05). Conclusion: The results of this study indicate that cimiracemate A confers some degree of protection on arthritic neonatal rats via a mechanism that involves regulation of iNOS/NF-κB/TLR-4 pathway.