Nature: New Discovery! Before the body infects the pathogen, the gut microorganisms may shape the body's production of a variety of antibodies!

August 9, 2020 // -- B-cells are white blood cells that develop antibodies that bind to harmful foreign particles (viruses or pathogenic bacteria, etc.) and block their invasion of the host and infection of the body cells, each B-cell carries a single B-cell receptacle (BCR) that helps determine the binding exogenous substance, as if each lock could accept a different key.
There are millions of B-cells in the body that carry different receptors, and the great diversity of B-cells stems from the rearrangement of the encoded receptogener genes, so that the receptors on each B-cell surface are slightly different, allowing them to identify billions of different harmful molecules;
Image source: CC0 Public Domain In a recent study published in the international journal Nature, scientists from the University of Bern and other institutions analyzed the expression of billions of genes produced by encoded antibodies in the system, which allows scientists to understand how genes respond to individual benign gut microbes.
The number of benign microorganisms living in the gut is about the same as the number of cells in the body, and most bacteria stay in the gut and cannot penetrate the body's tissues, but unfortunately some penetration of the gut microbiome is inevitable because the gut has only one layer of cells that separate/isolate the blood vessels we need to absorb food nutrients from the inside of the blood vessels.
researcher Limenitakis says we can use a specially designed computer program to process millions of genetic sequences that compare antibody pools in B cells, depending on whether microbes stay in the intestines or reach the bloodstream, in which case the antibody bank changes, but the way they change depends on how exposure occurs.
Interestingly, this can be predicted because it depends on the microbes that the researchers are concerned about and their exact location in the body, suggesting that gut microbes may guide the formation of antibodies before the body is seriously infected, a process that may not be random.
Compared to antibodies in the blood (IgM and IgG), antibodies (IgA) in the inner walls of the gut have different types, and using powerful genetic analysis techniques, the researchers found that the range of different antibodies produced in the gut may be much smaller than the antibodies produced in the body's central tissue, which means that once microbes enter the body, the immune system has a lot of possibilities to internally and eliminate these microorganisms, and the antibodies in the gut identify and bind mainly to the bacteria they see at any time.
researchers say mammals face many different microbial challenges throughout their life cycle, so it's important to know how antibody libraries are shaped by a particular microbe once they change, and then they answer that question by detecting changes in the same microbes at different points or changes in both microbes.
Although gut microbes do not directly produce many different antibodies, if they enter the blood will promote the central immune tissue become sensitive to produce antibodies, when the second microorganism appears, a fairly limited intestinal antibody response will change to adapt to the microorganism, it is like a lock on the door, which may be different from when microorganisms enter the blood to reach the central body tissue, when the second group of antibodies The first reaction to the original microbe may not be affected (like installing another lock so that different keys can be used to open the door), the researchers note, and the central body has the ability to remember a range of different microbiomes and avoid damage caused by sepsis, where different B-cell immunity strategies are important for maintaining peaceful coexistence with microbial "passengers." Li, the
's lead researcher, said the results not only revealed the composition of gut microbes for the first time, but also found that the body's exposure to certain symbymbic microbial members of the time and sequence may have occurred mainly in the early first wave of "planting", which may have an impact on the resulting B-cell receptor library and the body's immunity to pathogens.
source: Li, H., Limenitakis, J.P., Greiff, V. et al. Mucosal or systemic microbiota exposures shape the B cell repertoire. Nature (2020). doi:10.1038/s41586-020-2564-6.