# The Microbiome and Metabolic Dysfunction-Associated Steatotic Liver Disease

## TL;DR

This review explores how gut and liver microbes contribute to liver disease and discusses new treatments like phage therapy and dietary changes.

## Contribution

The paper highlights novel microbiota-based treatment strategies for MASLD, including phage therapy and synbiotics.

## Key findings

- Intestinal and hepatic microbiota play a key role in the development of MASLD.
- Phage therapy and dietary interventions show promise as new treatment approaches for MASLD.
- Bile acid and tryptophan metabolism by the microbiota influence MASLD pathogenesis.

## Abstract

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a condition wherein excessive fat accumulates in the liver, leading to inflammation and potential liver damage. In this narrative review, we evaluate the tissue microbiota, how they arise and their constituent microbes, and the role of the intestinal and hepatic microbiota in MASLD. The history of bacteriophages (phages) and their occurrence in the microbiota, their part in the potential causation of MASLD, and conversely, “phage therapy” for antibiotic resistance, obesity, and MASLD, are all described. The microbiota metabolism of bile acids and dietary tryptophan and histidine is defined, together with the impacts of their individual metabolites on MASLD pathogenesis. Both periodontitis and intestinal microbiota dysbiosis may cause MASLD, and how individual microorganisms and their metabolites are involved in these processes is discussed. Novel treatment opportunities for MASLD involving the microbiota exist and include fecal microbiota transplantation, probiotics, prebiotics, synbiotics, tryptophan dietary supplements, intermittent fasting, and phages or their holins and endolysins. Although FDA is yet to approve phage therapy in clinical use, there are multiple FDA-approved clinical trials, and this may represent a new horizon for the future treatment of MASLD.