Phenylpropionic acid produced by gut microbiota alleviates acetaminophen-induced hepatotoxicity

ABSTRACT

The gut microbiota affects hepatic drug metabolism. However, gut microbial factors modulating hepatic drug metabolism are largely unknown. In this study, using a mouse model of acetaminophen (APAP)-induced hepatotoxicity, we identified a gut bacterial metabolite that controls the hepatic expression of CYP2E1 that catalyzes the conversion of APAP to a reactive, toxic metabolite. By comparing C57BL/6 substrain mice from two different vendors, Jackson (6J) and Taconic (6N), which are genetically similar but harbor different gut microbiotas, we established that the differences in the gut microbiotas result in differential susceptibility to APAP-induced hepatotoxicity. 6J mice exhibited lower susceptibility to APAP-induced hepatotoxicity than 6N mice, and such phenotypic difference was recapitulated in germ-free mice by microbiota transplantation. Comparative untargeted metabolomic analysis of portal vein sera and liver tissues between conventional and conventionalized 6J and 6N mice led to the identification of phenylpropionic acid (PPA), the levels of which were higher in 6J mice. PPA supplementation alleviated APAP-induced hepatotoxicity in 6N mice by lowering hepatic CYP2E1 levels. Moreover, PPA supplementation also reduced carbon tetrachloride-induced liver injury mediated by CYP2E1. Our data showed that previously known PPA biosynthetic pathway is responsible for PPA production. Surprisingly, while PPA in 6N mouse cecum contents is almost undetectable, 6N cecal microbiota produces PPA as well as 6J cecal microbiota in vitro, suggesting that PPA production in the 6N gut microbiota is suppressed in vivo. However, previously known gut bacteria harboring the PPA biosynthetic pathway were not detected in either 6J or 6N microbiota, suggesting the presence of as-yet-unidentified PPA-producing gut microbes. Collectively, our study reveals a novel biological function of the gut bacterial metabolite PPA in the gut-liver axis and presents a critical basis for investigating PPA as a modulator of CYP2E1-mediated liver injury and metabolic diseases.

KEYWORDS:

• Mouse gut microbiota
• metabolomics
• CYP2E1
• acetaminophen
• hepatotoxicity
• liver injury
• fldC
• phenylpropionic acid

Disclosure statement

No potential conflict of interest was reported by the authors.

Authors contributions

Conceptualization, S.C., H.L, and H.J.; investigation, S.C., X.Y., K-J.W., V.L., N.H., E.C., E.C., J-S.P., G.G., and Y.K.; resources, E.C., O-N.B., H.L. and H.J.; writing – original draft, S.C. and H.J.; writing – review & editing, H.L. and H.J.; supervision, H.L. and H.J.

Data availability statement

16S rRNA amplicon sequencing data have been deposited under the NCBI BioProjects (https://www.ncbi.nlm.nih.gov/bioproject/) PRJNA604264 (6J/6N cohousing and gut microbiota transplantation), PRJNA940413 (6J/6N cecal microbiota), and PRJNA604973 (PPA supplementation). Any additional information required to reanalyze the data reported in this study will be available upon request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19490976.2023.2231590

Additional information

Funding

This work was funded by the Chicago Biomedical Consortium with support from the Searle Funds at The Chicago Community Trust (H.J. and E.C.) and the Purdue Center for Cancer Research (NIH P30 CA023168). Y.K. and O-N.B. received support from the Ministry of Health & Welfare (HI19C0748) and the National Research Foundation (RS-2023-00217123), Republic of Korea. V.A.L. received support from NIH T32 DK007074. The University of Chicago Gnotobiotic Facility was supported by NIDDK P30DK042086 Digestive Disease Research Core Center.