[Nature] new discovery: intestinal microbes affect B cells and antibody pool

The effect of intestinal microorganisms on human health is one of the hot research fields in recent years. A large number of studies have shown that intestinal microorganisms play an important role in human health. Recently, researchers at the University of Bern analyzed that

B cells are white blood cells that can produce antibodies. These antibodies or immunoglobulins can bind to harmful foreign particles and prevent them from invading and infecting human cells. Each B cell carries a separate B cell receptor, which determines which particles it can bind, just as each lock receives a different key.

there are millions of B cells in the human body, which have different receptors. This huge diversity comes from the rearrangement of the genes that encode these receptors, so that the receptors in each B cell are slightly different, resulting in billions of different potentially recognizable harmful molecules. Intestinal microbes trigger the expansion of these B-cell populations and the production of antibodies, but until now it is not known whether this is a random process or whether the molecules of the gut microbiota itself influence the results.

the number of benign microbes in our gut is roughly the same as the number of cells in our body. Most of these bacteria stay in the gut, rather than penetrate into human tissues. Unfortunately, some penetration is inevitable because the gut has only one layer of cells that separate the blood vessels and tubes that we need to absorb food.

researchers use specially designed computer programs to process millions of gene sequences that compare antibody pools from B cells, depending on whether the microbes remain in the gut or enter the blood. In both cases, the antibody pool changed, but in a different way, depending on the way the exposure occurred.

compared with the antibodies in blood, there are different kinds of antibodies in intestinal wall. Through powerful genetic analysis, the researchers found that the range of different antibodies produced by the gut is much smaller than that produced by the body’s central tissue. This means that once microbes enter the body, the immune system is more likely to neutralize and destroy them, while the antibodies in the gut mainly bind to bacterial molecules that can be seen at any time.

mammals face a variety of microbial challenges in their lifetime. Therefore, it is important to know how the antibody library will change once some other microorganism appears and is stereotyped by a specific microorganism. The team answered this question by testing what happened to the same microbes in different locations or two different microbes in another location.

although intestinal microbes do not directly produce a wide range of different antibodies, if they enter the blood, they will sensitize the central immune tissue and produce antibodies. When a second microorganism appears, a fairly limited intestinal antibody response changes to accommodate the organism.

this is different from that when the second group of antibodies produces the second group of antibodies without damaging the first reaction to the original microorganism, the microorganism enters the blood and reaches the central human tissue. This suggests that central tissue has the ability to remember many different microbial species and avoid the risk of sepsis. It also shows that using different B-cell immune strategies in different parts is very important to maintain our peaceful survival with microorganisms. Pets