Monosodium Urate Crystals Regulate a Unique JNK-Dependent Macrophage Metabolic and Inflammatory Response

The response of macrophages to monosodium urate crystals (MSUc) is incompletely understood partly due to the use of a toll-like receptor (TLR)-induced priming step in cell lines. Yet, MSUc induce inflammation in vivo without prior priming, raising the possibility of an initial cell-autonomous phase that is TLR-independent. Here, using genome wide transcriptomic analysis and biochemical assays we demonstrate that MSUc alone induce a metabolic-inflammatory transcriptional program in non-primed human and murine macrophages that is markedly distinct to that induced by LPS. Genes uniquely upregulated in response to MSUc belonged to lipid and amino acid metabolism, glycolysis, and SLC transporters. This upregulation led to a metabolic rewiring in sera from individuals and mice with acute gouty arthritis. Mechanistically, the initiating inflammatory-metabolic changes in acute gout flares are regulated through a persistent expression and increased binding of JUN to the promoter of target genes through JNK signaling -but not P38- in a process that is different than after LPS stimulation and unexpectedly independent of inflammasome activation. Finally, pharmacological JNK inhibition limited MSUc-induced inflammation in animal models of acute gouty inflammation. MSUc alone induce a unique strong macrophage activation and distinct phenotype that forces a reconsideration of initiating mechanisms in acute gout flares.