Gut microbiota is a microecosystem composed of various microorganisms. It plays an important role in human metabolism, and its metabolites affect different tissues and organs. Intestinal flora maintains the intestinal mucosal barrier and interacts with the immune system. The liver is closely linked to the intestine by the gut-liver axis.
As the first organ that comes into contact with blood from the intestine, the liver will be deeply influenced by the gut microbiota and its metabolites, and the intestinal leakage and the imbalance of the flora are the trigger of the pathological reaction of the liver.
In this paper, we discuss the role of gut microbiota and its metabolites in the pathogenesis and development of autoimmune liver diseases((including autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis), metabolic liver disease such as non-alcoholic fatty liver disease, cirrhosisits and its complications, and liver cancer from the perspective of immune mechanism.
And the recent progress in the treatment of these diseases was reviewed from the perspective of gut microbiota.
Conclusion and Prospect
Gut microbiota is usually considered to be closely related to metabolic diseases. Since our human body is an organic whole, exploring this vital symbiotic ecosystem will surely lead us to further comprehension to various diseases.
At the same time, the intestinal flora can also be regarded as a corresponding therapeutic target, providing another perspective for the development of clinical pharmacy.
Therefore, it is of great significance to clarify the role of the intestinal flora in diseases of different systems.
In this article, we reviewed the role of the gut microbiota in various liver diseases and interventions that target at it for therapy.
In general, the liver and the intestine have a close connection through the gut-liver axis. The destruction of the intestinal barrier and the imbalance of the gut microbiota are the initiating factors that cause hepatic lesions. In different kinds or stages of hepatopathy, the composition of the gut microbiota is disparate. LPS, SCFAs, BA, and other bacterial metabolites are the main signals inducing immune responses in liver tissue. The TLR family plays a key role in mediating these signals to produce liver inflammation. In terms of treatment, antibiotics, probiotics, prebiotics, synbiotics, and fecal microbiota transplantation are the main therapeutic methods targeting at gut microbiota, and their effectiveness has been confirmed in animal experiments and some small clinical studies.
However, current researches on the gut microbiota and liver diseases also face the following challenges. First of all, most of these researches are animal experiments, which aim to explain the potential correlation between gut microbiota and liver diseases, and few of them can form an exact and coherent pathological mechanism. Therefore, more in-depth human researches are urgently needed to verify these potential mechanisms. Secondly, the intestinal flora is susceptible to genetic, environmental, behavioral and other factors, and further multi-racial, long-term, multicenter studies and better matching controls are needed to explore the association between the intestinal flora and specific diseases.
The diversity of gut flora and the differences between individuals make it important to look for core flora that really works. With the development of sequencing technology and the revolution in metagenomics, enterotype have been proposed to characterize the intestinal flora. Through the analysis of the enterotype, the characteristics of core flora will be extracted to discover more potential next-generation probiotics(NGPs). In the future, the efficacy and safety of the NGPs may be tested through clinical studies. And we may see NGPs developed for specific health problems, enabling customized probiotics for patients.
Date: 13 July 2022
Department of Infection, Guang’anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, China
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