Alcohol-related liver disease (ALD) is a major cause of mortality and disability adjusted life years. It is not fully understood why a small proportion of patients develop progressive forms of ALD (e.g. fibrosis, cirrhosis). Differences in the metabolic processes could be behind the individual progression of ALD. Our aim was to examine differences in serum metabolome between patients with non-progressive ALD and patients with an early form of progressive ALD. The study had three study groups: progressive ALD (alcohol-related steatohepatitis or early-stage fibrosis, n=50), non-progressive ALD (simple steatosis, n=50) and healthy controls (n=32). Both ALD groups took part in a voluntary alcohol rehabilitation program. A non-targeted metabolomics analysis and targeted analysis of short chain fatty acids was done to the serum samples taken on the day of admission. We found 111 significantly (p<0.0005) altered identified metabolites between the study groups. Our main finding was that levels of glycine conjugated bile acids, glutamic acid, 7-methylguanine and several phosphatidylcholines were elevated in the progressive ALD group in comparison to both the non-progressive ALD group and the controls. Glycine conjugated bile acid, glutamic acid and 7-methylguanine also positively correlated with increased levels of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, cell death biomarker M65, and liver stiffness. Our results indicate that the enterohepatic cycle of glycine conjugated bile acids as well as lipid and energy metabolism are altered in early forms of progressive ALD. These metabolic processes could be a target for preventing progression of ALD.

OK and KH are founders of Afekta Technology Ltd., a company providing metabolomics analysis services. Other authors do not have any conflict of interests.

The metabolomics analyses were supported by the Finnish Foundation for Alcohol Studies (OK). HA and KH are supported by the Research Council of Finland (321716), ERA-NET NEURON (334814) and Jane and Aatos Erkko Foundation. SL is a research associate from FRS-FNRS. PS is supported by grants from the Fond national de la recherche scientifique (FNRS T.0217.18, T.0195.22, J.0171.21, J.0195.24).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethics committee Comite d ethique Hospitalo-facultaire Saint-Luc UCLouvain gave ethical approval for this work (B403201422657).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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The data that support the findings of this study are available on request from the corresponding author, OK.