The international group of scientists revealed the connection of diet and immunity mediated through the intestinal microflora. Experiments on mice have shown that the development of by-products of germs of microbes living in the intestine depends on the diet, which, in turn, affects immune defense. The results of the study are published in the Nature magazine.
In the experimental series, the command determined the cascade of immune signals, launched by the metabolic decay of food amino acids in the intestine of the mouse. First, the animal consumes food containing branched amino acids with branched side chains, which are then absorbed by the Bacteroides Fragilis bacteria living in the intestine. Bacteria, in turn, produces branched chains liposaccharides, which are captured by immune signal cells, known as antigen presenting cells.
Antigen presenting cells play the role of activators of another class of immune cells – natural killers. This type of T-cells that recognize and destroy infected cells, and also participate in antitumor protection. Scientists have shown that the transmission of signals from B.Fragilis to immune cells occurs only in the case of branched side chains molecules. Bacterium, absorbing amino acids, changes the structure of liposaccharid molecules in such a way that they are better associated with receptors on immune cells and initiate a signal cascade, overwhelming inflammation.
researchers synthesized 23 different configurations of immunomodulatory liposaccharides to determine how each molecule interacts with immune cells regulating inflammation. The molecules with a branched chain forced the natural killers to release the interleukin-2 signal connection (IL-2), while the molecules with a direct chain did not do this.
Experiments on mice with ulcerative colitis showed that animals that received branched chain liposaccharides lived much better than animals that did not receive treatment. In rodent cells, the minimum signs of colon inflammation were observed. According to researchers, the results contribute to the development of new methods of treating diseases of the gastrointestinal tract mediated by natural killers.