Uric acid activates aldose reductase and the polyol pathway for endogenous fructose and fat production causing development of fatty liver in rats.
Level 5 - mechanism / opinion, no new human data
Preclinical in vitro cell culture and in vivo animal mechanistic study.
PubMed 30651350 · doi:10.1074/jbc.RA118.006158
What was done
Investigators evaluated whether soluble uric acid stimulates aldose reductase, a key enzyme in the polyol pathway, to drive endogenous fructose and lipid accumulation. Using biochemical assays, reporter gene expression, and confocal fluorescence microscopy, they tested uric acid exposure in cultured human hepatocytes (HepG2 cells) with and without glucose. In vivo, they assessed hepatic aldose reductase expression, endogenous fructose levels, and fat accumulation in hyperuricemic rats, including the effect of co-administering the xanthine oxidase inhibitor allopurinol.
What was found
Uric acid dose-dependently stimulated aldose reductase expression, endogenous fructose production, and triglyceride accumulation in HepG2 cells via oxidative stress and activation of the transcription factor NFAT5. Uric acid also amplified glucose-driven triglyceride accumulation in vitro. Hyperuricemic rats showed elevated hepatic aldose reductase expression, endogenous fructose accumulation, and liver fat buildup, all of which were significantly reduced by allopurinol. The abstract reports no numerical values, effect sizes, or exact p-values.
Why it matters
This study outlines a mechanistic positive feedback loop wherein uric acid drives endogenous hepatic fructose and lipid synthesis via the polyol pathway, proposing a biochemical link between hyperuricemia, dietary sugars, and nonalcoholic fatty liver disease.
Limits
The study is entirely preclinical, relying on an immortalized cell line (HepG2) and a rat model, which may not reflect human in vivo physiology. The abstract provides no sample sizes (n), uric acid or drug dosages, or quantitative effect estimates.
Cited by
- supports Elevated uric acid levels directly stimulate and activate aldose reductase, driving further endogenous fructose production.