Ketohexokinase inhibition improves NASH by reducing fructose-induced steatosis and fibrogenesis

Background and Aims It is estimated that Non-Alcoholic Fatty Liver Disease (NAFLD) may affect up to 25% of the adult population worldwide presenting an enormous challenge for healthcare providers and significant mortality risk for those affected. Increasing evidence highlights dietary fructose as a major driver of NAFLD pathogenesis, the majority of which is cleared on first pass through the hepatic circulation by enzymatic phosphorylation to fructose-1-phosphate via ketohexokinase (KHK) enzyme. Without a current approved therapy, disease management emphasizes lifestyle interventions, but few patients adhere to such strategies. New targeted therapies are urgently required. Methods We have used a unique combination of human liver specimens, a murine dietary model of NAFLD and human multicellular coculture systems to understand the hepatocellular consequences of fructose administration. We have also performed a detailed NMR-based metabolic tracing of the fate of isotopically-labelled fructose upon administration to the human liver. Results Expression of KHK isoforms is found in multiple human hepatic cell types, although hepatocyte expression predominates. KHK-KO mice show a reduction in serum transaminase, reduced steatosis and altered fibrogenic response on Amylin diet. Human cocultures exposed to fructose exhibit steatosis and activation of lipogenic and fibrogenic gene expression which were reduced by pharmacological inhibition of KHK activity. Analysis of human livers exposed to ¹³C-labelled fructose confirmed the steatosis, and associated effects were due to accumulation of lipogenic precursors such as glycerol and enhanced glycolytic activity. All of these were dose-dependently reduced by administration of KHK inhibitor. Conclusions We have provided pre-clinical evidence using human livers to support use of KHK inhibition to improve steatosis, fibrosis and inflammation in the context of NAFLD.