Intestinal microbiota and liver–intestine axis: what is it?
The intestinal microbiota is the set of microorganisms that colonize the digestive tract.
These microorganisms live in symbiosis with the human body and play an important role in maintaining optimal health.
Among the problems that are related to intestinal dysbiosis there are several pathologies such as:
- irritable bowel syndrome
- type 2 diabetes
- liver pathologies
Its the communication relationship between the liver and the intestine, which takes place via the portal vein, bile acids and the systemic circulation, which is defined as the liver–intestine axis.
Among the three routes mentioned above, the portal vein is the main one.
Here flows the blood coming from the organs that make up the digestive tract such as the spleen, pancreas and gallbladder.
Liver-intestine axis: state of health
If the microbiota undergoes changes that alter its normal functionality, a state of inflammation can arise which is capable of altering the normal functionality of the intestinal barrier.
This, in fact, due to the breakdown of the tight junctions of the epithelium, loses its integrity and allows the passage of both microorganisms and metabolites.
These can reach the liver and cause an inflammatory process which, if prolonged over time, can cause loss of function of the affected liver tissue.
The liver-intestine axis influences the onset of various chronic liver diseases which are mainly divided into two:
- alcohol-related liver disease (ALD)
- non-alcohol related fatty liver disease (NAFLD)
Excessive alcohol consumption is one of the main causes of the impairment of the integrity of the tight junctions of the intestinal barrier which results in greater permeability, in the inflammatory state of the intestine and in the modification of the intestinal microbiota.
Alcohol abuse involves a decrease in the Clostridiales that make up the microbiota responsible for the production of butyrate and an increase in the Enterobacteriaceae species which have a pro-inflammatory effect.
Liver diseases not related to alcohol abuse are the consequence of the accumulation of triglycerides in the hepatocytes and intestinal dysbiosis.
These conditions, in some of the NAFLD patients, can cause the onset of a chronic inflammatory state that can lead to cirrhosis and liver cancer. An abnormal intestinal microbiota is in fact common in patients with liver cancer.
Intestinal dysbiosis and its damage to the intestinal barrier seem to be common factors in many chronic liver diseases.
Among the therapeutic approaches, the importance of probiotics seems to be gaining ground even if further studies will be necessary to confirm the effective functionality of probiotics as a therapeutic tool. Once again it is impossible not to be amazed and fascinated by the complexity of the functioning of the human body.
At the end of this reading, the certainty remains that the liver and intestine communicate in a constant and so important way as to be a pillar for our well-being.
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