Liver injury, endotoxemia, and their relationship to intestinal microbiota composition in alcohol-preferring rats

Liver Injury, Endotoxemia, and Their Relationship toIntestinal Microbiota Composition in Alcohol-PreferringRatsBrunella Posteraro*, Francesco Paroni Sterbini*, Valentina Petito, Stefano Rocca,Tiziana Cubeddu, Cristina Graziani, Vincenzo Arena, Gabriele A. Vassallo, Carolina Mosoni,Loris Lopetuso, Irene Lorrai, Paola Maccioni, Luca Masucci, Cecilia Martini,Antonio Gasbarrini, Maurizio Sanguinetti, Giancarlo Colombo, and Giovanni AddoloratoBackground:There is strong evidence that alcoholism leads to dysbiosis in both humans and ani-mals. However, it is unclear how changes in the intestinal microbiota (IM) relate to ethanol (EtOH)-induced disruption of gut-liver homeostasis. We investigated this issue using selectively bred Sardinianalcohol-preferring (sP) rats, a validated animal model of excessive EtOH consumption.Methods:Independent groups of male adult sP rats were exposed to the standard, home-cage 2-bot-tle "EtOH (10% v/v) versus water" choice regimen with unlimited access for 24 h/d (Group Et) for 3(T1), 6 (T2), and 12 (T3) consecutive months. Control groups (Group Ct) were composed of matched-age EtOH-naEUR?ve sP rats. We obtained samples from each rat at the end of each experimental time, andwe used blood and colon tissues for intestinal barrier integrity and/or liver pathology assessments andused stool samples for IM analysis with 16S ribosomal RNA gene sequencing.Results:Rats in Group Et developed hepatic steatosis and elevated serum transaminases and endo-toxin/lipopolysaccharide (LPS) levels but no other liver pathological changes (i.e., necrosis/inflamma-tion) or systemic inflammation. While we did not find any apparent alteration of the intestinal colonicmucosa, we found that rats in Group Et exhibited significant changes in IM composition compared tothe rats in Group Ct. These changes were sustained throughout T1, T2, and T3. In particular,Ruminococcus,Coprococcus,andStreptococcuswere the differentially abundant microbial genera at T3.The KEGG Ortholog profile revealed that IM functional modules, such as biosynthesis, transport, andexport of LPS, were also enriched in Group Et rats at T3.Conclusions:We showed that chronic, voluntary EtOH consumption induced liver injury and endo-toxemia together with dysbiotic changes in sP rats. This work sets the stage for improving our knowl-edge of the prevention and treatment of EtOH-related diseases