ABSTRACT
BACKGROUND There is mounting evidence that microbes resident in the human intestine contribute to diverse alcohol-associated liver diseases (ALD) including the most deadly form known as alcohol-associated hepatitis (AH). However, mechanisms by which gut microbes synergize with excessive alcohol intake to promote liver injury are poorly understood. Furthermore, whether drugs that selectively target gut microbial metabolism can improve ALD has never been tested.
METHODS We used liquid chromatography tandem mass spectrometry to quantify the levels of microbe and host choline co-metabolites in healthy controls and AH patients, finding elevated levels of the microbial metabolite trimethylamine (TMA) in AH. In subsequent studies, we treated mice with non-lethal bacterial choline TMA lyase (CutC/D) inhibitors to blunt gut microbe-dependent production of TMA in the context of chronic ethanol administration. Indices of liver injury were quantified by complementary RNA sequencing, biochemical, and histological approaches. In addition, we examined the impact of ethanol consumption and TMA lyase inhibition on gut microbiome structure via 16S rRNA sequencing.
RESULTS We show the gut microbial choline metabolite trimethylamine (TMA) is elevated in AH patients and correlates with reduced hepatic expression of the TMA oxygenase flavin-containing monooxygenase 3 (FMO3). Provocatively, we find that small molecule inhibition of gut microbial CutC/D activity protects mice from ethanol-induced liver injury. CutC/D inhibitor-driven improvement in ethanol-induced liver injury is associated with distinct reorganization of the gut microbiome and host liver transcriptome.
CONCLUSIONS The microbial metabolite TMA is elevated in patients with AH, and inhibition of TMA production from gut microbes can protect mice from ethanol-induced liver injury.
Competing Interest Statement
T.M., A.K., V.V., N.S., E.H., R.B., A.L.B., K.K.F., W.M., C.N., D.O., L.J.O., R.C.S., M.R.M., A.B., K.L.P., A.K., V.P., M.M., J.T.A., B.W. C.J.M., M.M., A.J.M., S.R., B.B., S.D. D.M.R., D.S.A. L.E.N., and J.M.B. all declare no competing financial interests. R.N.H. reports being a paid consultant for the University of Cincinnati. Z.W. and S.L.H. report being named as co-inventor on pending and issued patents held by the Cleveland Clinic relating to cardiovascular diagnostics and therapeutics. S.L.H. reports being a paid consultant for Zehna Therapeutics, having received research funds from Zehna Therapeutics, Procter & Gamble, and Roche Diagnostics. S.L.H. and Z.W. report being eligible to receive royalty payments for inventions or discoveries related to cardiovascular diagnostics or therapeutics from Zehna Therapeutics, Cleveland Heart Lab, a wholly owned subsidiary of Quest Diagnostics, and Procter & Gamble. G.S. reports being a paid consult for Allergan, Alnylam, Arrow, Durcect Corporation, Generon, Glympse Bio, Terra Firma, Quest Diagnostics, Pandion Therapeutics, Surrozen, and Zomagen. G.S. has received grants from Gilead, Genfit, Intercept, Novartis, SignaBlok, and Shire; she also holds intellectual property rights with Up to Date. J.C.G-G is an employee of The Procter & Gamble Co. J.A.B. reports being eligible to receive royalty payments for inventions or discoveries related to cardiovascular therapeutics from Zehna Therapeutics, and the Proctor & Gamble Co.