Abstract
BACKGROUND & AIMS
Alcohol disturbs hepatic lipid synthesis and transport, but the role of lipid dysfunction in alcohol-related liver disease (ALD) is unclear. In this biopsy-controlled, prospective, observational study, we characterized the liver and plasma lipidomes in patients with early ALD.
METHODS
We performed mass spectrometry-based lipidomics of paired liver and plasma samples from 315 ALD patients, and of plasma from 51 matched healthy controls. We associated lipid levels to histological fibrosis, inflammation and steatosis with correction for multiple testing and adjustment for confounders. We further investigated sphingolipid regulation by qPCR sequencing of miRNA, prediction of liver-related events, and tested causality with Mendelian randomization.
RESULTS
We detected 198 lipids in the liver and 236 lipids in the circulation from 18 lipid classes. Most sphingolipids (sphingomyelins and ceramides) and phosphocholines were co-downregulated in both liver and plasma, where lower abundance correlated with higher fibrosis stage. Sphingomyelins showed the most pronounced negative correlation to fibrosis, mirrored by negative correlations in both liver and plasma with hepatic inflammation. Reduced sphingomyelins furthermore predicted future liver-related events. This seemed to be characteristic of 'pure ALD', as sphingomyelin levels were higher in patients with concomitant metabolic syndrome and ALD/NAFLD overlap. Mendelian randomization in FinnGen and UK Biobanks indicated ALD as the cause of low sphingomyelins, while alcohol use disorder did not correlate with genetic susceptibility to low sphingomyelin levels.
CONCLUSION
Alcohol-related liver fibrosis is characterized by selective and progressive lipid depletion in liver and blood, particularly sphingomyelins, which also associates with progression to liver-related events.
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