Non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are some of the most common liver diseases worldwide. The human gut microbiome is dynamic and shifts in bacterial composition have been implicated in many diseases. Studies have shown that there is a shift in bacterial overgrowth favoring pro-inflammatory mediators in patients with advanced disease progression such as cirrhosis. Further investigation demonstrated that the transplantation of gut microbiota from advanced liver disease patients can reproduce severe liver inflammation and injury in mice. Various techniques in manipulating the gut microbiota have been attempted including fecal transplantation and probiotics. This review focuses on the changes in the gut microbiota as well as emerging lines of microbiome work with respect to NAFLD and ALD.
General challenges in conducting and interpreting microbiome studies and its implications for NAFLD and ALD
Despite technical advances in the rapidly evolving field of microbiome research, the reproducibility and validity of findings deserve special attention. Large data sets with several competing variables often confound the observations compared to a rather clean disease state in an experimental model. In addition, complex ecosystem of host, genetics, and environmental factors such as the mode of delivery, diet, alcohol, medications, antibiotic use, etc. can cause variations in the composition as well as functionality of the gut microbiome. Another important but often overlooked technical aspect in human microbiome studies is the collection, processing and handling of the bio specimens and the use of different sequencing methods, which yield different results. Therefore, designing future studies in liver disease research should focus on overcoming some of these challenges to produce more robust, reproducible, generalizable and clinically applicable data at an individual and population level.
Reference
Kwong EK, Puri P. Gut microbiome changes in Nonalcoholic fatty liver disease & alcoholic liver disease. Translational Gastroenterology and Hepatology. ۲۰۲۱; ۶.
