Abstract
We previously synthesized the xanthine oxidoreductase (XOR) inhibitor WN1703. In addition to showing XOR inhibitory effects, WN1703 also showed anti-inflammatory effects in a rat hyperuricemia model. Here, we studied WN1703's anti-inflammatory effects on gout and explored the underlying mechanisms. Tohoku Hospital Pediatrics-1 (THP-1) cells were stimulated by lipopolysaccharide/interferon-γ/monosodium urate (MSU). The levels of inflammatory cytokines in the supernatant and protein expression in THP-1 cells were detected using enzyme-linked immunosorbent assay (ELISA) kits and western blotting, respectively, to verify the inhibitory effects of WN1703 and its mechanism. Potassium oxonate, hypoxanthine, and MSU were administered to establish a hyperuricemia rat model complicated by acute gouty arthritis. At 1-24 h after MSU injection, the degree of ankle swelling was recorded to compare the anti-inflammatory effects at each time point. The potential mechanism was further explored using immunohistochemistry and ELISA. WN1703 significantly downregulated expression of nucleotide-binding oligomerization domain-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, toll-like receptor-4 (TLR4), myeloid differentiation primary response protein 88 (MyD88), nuclear factor-kappa B (NF-κB), and relevant cytokine levels in THP-1 cells. Identical doses of WN1703 and febuxostat had comparable effects on these proteins and cytokines. In the gout rats, the same dose of WN1703 and febuxostat showed equivalent inhibitory effects on NLRP3, ASC, and NF-κB; however, WN1703 showed weaker impacts on alleviating ankle swelling than febuxostat showed. In conclusion, WN1703 showed significant anti-inflammatory effects in hyperuricemic rats with acute gout. Such effects were related to the inhibition of the NLRP3/ASC/Caspase-1 and TLR4/MyD88/NF-κB signaling pathways, thereby downregulating inflammation-related protein expression and decreasing inflammatory cytokine secretion.