Gut microbiota as important modulator of metabolism in health and disease

Abstract

The human gastrointestinal tract colonizes a large number of microbial microflora, forms a host-microbiota co-metabolism structure with the host to participate in various metabolic processes in the human body, and plays a major role in the host immune response. In addition, the dysbiosis of intestinal microbial homeostasis is closely related to many diseases. Thus, an in-depth understanding of the relationship between them is of importance for disease pathogenesis, prevention and treatment. The combined use of metagenomics, transcriptomics, proteomics and metabolomics techniques for the analysis of gut microbiota can reveal the relationship between microbiota and the host in many ways, which has become a hot topic of analysis in recent years. This review describes the mechanism of co-metabolites in host health, including short-chain fatty acids (SCFA) and bile acid metabolism. The metabolic role of gut microbiota in obesity, liver diseases, gastrointestinal diseases and other diseases is also summarized, and the research methods for multi-omics combined application on gut microbiota are summarized. According to the studies of the interaction mechanism between gut microbiota and the host, we have a better understanding of the use of intestinal microflora in the treatment of related diseases. It is hoped that the gut microbiota can be utilized to maintain human health, providing a reference for future research.

Fig. 1. The effects of gut microbiota on the host are reflected in different aspects, such as metabolism and gene. Therefore, single-level data is difficult to explain the full impact of gut microbiota on the host. Metagenomics performs unbiased DNA sequencing of whole intestinal microflora, and classifies and summarizes their gene functions using a database. Proteomics, which sequences the protein structure of the host or intestinal bacterial cells to obtain cell metabolism and changes in the cell network, measures the activity of the cell enzymes directly. Metabolomics is used for the quantitative analysis of small molecules produced by cell metabolism. Metabolomics combined with metagenomics can be used to discover relevant pathways in microbial metabolism, expounding its physiological role. Transcriptomics studies the complete RNA molecules in intestinal microflora, measures the dynamic expression of RNA molecules under different genomic conditions and reveals the genotype of gut microbiota under disease conditions. The application of multi-omics takes a new phase in the study of gut microbiota, providing predictions for therapeutic targets for complex diseases.

Fig. 2. Under homeostasis between gut microbiota and the host, intestinal bacteria can metabolize drugs, promote browning of white fat, and convert dietary or compound water compounds into nutrients for host utilization. The gut microbiota and the host's liver and brain form the gut–liver axis and gut–brain axis, respectively, which participate in the life metabolic activities of various organs. Once the intestinal microflora become imbalanced, liver diseases, gastrointestinal diseases, and nervous system diseases will be induced. Specific diseases are shown in the figure.