Anti-Inflammatory Effect of Glycosaminoglycan Derived From Gryllus bimaculatus (A Type of Cricket, Insect) on Adjuvant-Treated Chronic Arthritis Rat Model

Anti-inflammatory effects of glycosaminoglycan (GAG) derived from cricket (Gryllus bimaculatus, Gb) were investigated in a complete Freund's adjuvant (CFA)-treated chronic arthritic rat model. This GAG produced a significant anti-edema effect as evidenced by inhibition of C-reactive protein (CRP) and rheumatoid factor, and interfered with atherogenesis by reducing proinflammatory cytokine levels of (1) vascular endothelial growth factor (VEGF) production in human umbilical vein endothelial cells (HUVEC), (2) interleukin-6, (3) prostaglandin E-2-stimulated lipopolysaccharide in RAW 264.7 cells, and (4) tumor necrosis factor (TNF)-alpha production in normal splenocytes, in a dose-dependent manner. This GAG was also found to induce nitric oxide (NO) production in HUVEC cells and elevated endothelial nitric oxide synthase (eNOS) activity levels. Histological findings demonstrated the fifth lumbar vertebrae (LV) dorsal root ganglion, which was linked to the paw treated with Gb GAG, was repaired against CFA-induced cartilage destruction. Further, combined indomethacin (5 mg/kg)-Gb GAG (10 mg/kg) inhibited more effectively CFA-induced paw edema at 3 h and 2 or 3 d after treatment to levels comparable to only the anti-inflammatory drug indomethacin. Ultraviolet (UV)-irritated skin inflammation also downregulated nuclear factor kappa B (NF kappa B) activity in transfected HaCaT cells. Data suggest that the anti-inflammatory effects of GAG obtained from cricket (Gb) may be useful for treatment of inflammatory diseases including chronic arthritis.