Unraveling the role of the gut microbiome in a rodent model of alcohol use disorder

About This Grant

PROJECT ABSTRACT Alcohol use disorder (AUD) is a leading cause of disability in the US, affecting 28.9 million people as of 2023. Despite the prevalence of AUD, treatment options remain limited and ineffective, highlighting the critical need for the development of novel therapeutics for AUD. Although AUD is often linked to liver, heart, and brain damage, recent studies have also implicated immune dysregulation in AUD. One potential link between AUD and immune dysregulation is the gut microbiome, a dynamic network of microorganisms essential in maintaining host homeostasis. The gut microbiome is known to regulate central nervous system (CNS) and immune functions through the gut microbiome, a two-way communication pathway between the gut and the CNS. As chronic heavy alcohol consumption is known to cause gut dysbiosis (imbalance of the gut microbiome) and the gut microbiome is critical for the development and maturation of the innate and adaptive immune systems, it is possible that the gut microbiome may play a role in driving both AUD and its associated immune deficits. Our research leverages high drinking in the dark mice (iHDID), a genetic rodent model for heightened alcohol consumption, to explore the role of the gut-brain axis in AUD. The overall objective of this proposal is to determine whether: 1) iHDID gut microbial species are not significantly altered by alcohol consumption and/or 2) iHDID gut microbiota contribute to heightened alcohol consumption. In Aim 1, using shotgun metagenomic sequencing, we will elucidate the extent to which bacterial/fungal gut microbiota shift following alcohol exposure in iHDID mice, relative to C57BL/6J (a popular strain used by alcohol researchers) and HS/Npt (the iHDID founding strain) controls. We will also quantify volatile organic compounds in the blood/feces to determine secretion of potentially immunomodulatory microbial metabolites. In Aim 2, we will determine whether the iHDID microbiome may drive increased drinking behavior using fecal microbiota transfer (FMT) from either alcohol-naive iHDID or C57BL/6J mice to alcohol-naive C57/BL6J mice and measuring recipients’ subsequent performance in a drinking procedure. Further, to examine whether FMT-induced increases in alcohol consumption stem from immune changes in the gut, I will quantify differential gene expression post-FMT in the brain using RNA 3’ tag-sequencing. This proposal employs several innovations: (i) iHDID mice, (ii) metagenomic sequencing, (iii) analysis of volatile organic compounds, (iv) 3’ RNA-tag sequencing, and (v) FMT. Our results will i) address a critical gap in knowledge on the interplay between alcohol, the gut microbiome, and immune function in AUD, ii) pave the way for the use of gut microbial analyses/manipulations in diagnosing/treating AUD, and iii) provide guidance towards improving outcomes for millions of AUD patients who lack effective diagnostics and therapies. Additionally, through the completion of this proposal and the guidance of my sponsors, I will receive extensive training to develop my professional and scientific skillset towards becoming an independent scientist.