1University of Lausanne, Center for Integrative Genomics and.
Plasma urate levels are higher in humans than rodents (240-360 µM vs. ~30 µM) because humans lack the liver enzyme uricase. High uricemia in humans may protect against oxidative stress but hyperuricemia also associates with the metabolic syndrome and urate and uric acid can crystallize to cause gout and renal dysfunctions. Thus, hyperuricemic animal models to study urate-induced pathologies are needed. We recently generated mice with liver-specific ablation of glut9, a urate transporter providing access of urate to uricase (LG9KO mice). LG9KO mice had moderately high uricemia (~120 µM). To further increase their uricemia, here we gavaged LG9KO mice for 3 days with inosine, a urate precursor; this treatment was applied in both chow and high fat-fed mice. In chow-fed LG9KO mice, uricemia peaked at 300 µM 2h after the first gavage and normalized 24h after the last gavage. In contrast, in high fat-fed LG9KO mice, uricemia further rose to 500µM. Plasma creatinine strongly increased, indicating acute renal failure. Kidneys showed tubule dilation, macrophage infiltration, and urate and uric acid crystals, associated with a more acidic urine. Six weeks after inosine gavage, plasma urate and creatinine had normalized. However, renal inflammation, fibrosis and organ remodeling had developed despite the disappearance of urate and uric acid crystals. Thus, hyperuricemia and high fat diet feeding combined to induce acute renal failure. Furthermore, a sterile inflammation caused by the initial crystal-induced lesions developed despite the disappearance of urate and uric acid crystals.
Glut9, acute renal failure, crystal, sterile inflammation, urate