HDL-cholesterol is commonly called good cholesterol, as opposed to LDL-cholesterol. They are in fact particles composed of lipids and proteins which transport cholesterol from the arteries to the liver where it will be eliminated: it thus makes it possible to eliminate the excess cholesterol found in the body. That is why it is important that the good cholesterol is above a certain level and the bad cholesterol is as low as possible. Especially since this good cholesterol could prove to be even more beneficial than expected if we are to believe the conclusions of a study carried out by researchers at the Washington University School of Medicine in St. Louis.
Published in the scientific journal “Science”, it suggests that a type of high-density lipoprotein called HDL3 has a previously unknown role in protecting the liver from injury and inflammation. Researchers have identified this special type of HDL cholesterol which, when produced in the gut, blocks intestinal bacterial signals that cause inflammation in the liver. If not blocked, these bacterial signals travel from the intestine to the liver, where they activate immune cells that trigger an inflammatory condition. This process causes damage that can lead to fatty liver disease or liver fibrosis in the long term.
What are the links between the intestines and the liver?
“The study in mice suggests that increasing levels of this specific type of HDL, and particularly in the gut, may hold promise for protection against liver disease, which, like heart disease, is a major chronic health problem. », Notes the study’s lead author, Prof. Gwendalyn J. Randolph. The team started from the observation that there is a link between the intestine and the liver and that certain intestinal microbes can produce an inflammatory molecule (lipopolysaccharide) which travels to the liver via the portal vein, the main vessel that supplies the liver. in blood and carries nutrients to the liver after absorption of food in the intestine.
However, substances from gut microbes can travel with nutrients to activate immune cells that trigger inflammation and this is how elementss of the gut microbiome can lead to liver disease. The researchers studied this problem in mice that had developed liver disease and thus showed “that HDL3 only leaves the portal vein and goes directly to the liver. As HDL3 travels through the portal vein, it binds to a protein called LBP, a beneficial process that prevents harmful molecules from activating the inflammatory process that promotes the appearance of liver damage.
Researchers also found that liver damage is worse when HDL3 in the gut is reduced, such as when removal of part of the intestine. They further showed that the same protective molecular complexes were present in human blood samples. Finally, they used a drug compound to increase HDL3 in the intestines of mice that have been shown to protect against different types of liver damage. Although the drug is only available for animal research, study reveals new leads treatment of liver disease, whether it comes from damage to the gut caused by high-fat diets, excessive alcohol consumption, or surgery.