Our powerful intestinal immune function may have been formed from the age of 14...

|Original compilation, reprint must indicate the source! What we learn from most biology textbooks is that the immune system of the fetus is largely underdeveloped, and it learns and grows after the fetus is born and exposed to the external environment.recently, a new study by the University of Pittsburgh School of medicine and the children's Hospital of the University of Pittsburgh Medical Center (UPMC) challenged this view, and for the first time comprehensively studied the developing intestinal immune system.the results of this study, published in the journal developmental cell, suggest that the immune function of the fetal gut is much more developed than previously thought.Lisa konnikova, a professor of pediatrics at the University of Pittsburgh School of medicine and a neonatologist at UPMC children's Hospital, said: "understanding the development of intestinal immunity is crucial because it may have a significant impact on the risk of developing autoimmune and inflammatory diseases such as inflammatory bowel disease in the future.this also opens the door to the development of new maternal vaccines, which can provide lifelong protection against major infectious diseases even before the birth of the fetus."image source: konnikova and his team used advanced cell and genomic analysis techniques, including large-scale cell counting and next-generation sequencing of B and T cell receptor libraries, to study the composition of the immune system in the intestinal tissues of fetuses aged 14 to 23 weeks and infants undergoing intestinal defect correction surgery.Image Source: konnikova, a developmental cell, said: "we were surprised to find that in the gut, almost complete immune function was formed as early as 14 weeks and remained stable throughout infancy."there are cells from both innate and adaptive immune systems in the gut of fetus.the innate immune system usually exists in the body and is not specific, but acts as a barrier, such as skin and immune cells, to respond quickly to invaders.the adaptive immune system is produced to deal with foreign substances, making it a specific immune system for specific invaders, but it needs to identify pathogens before they are affected.this can be achieved by immunization or pre infection.in the innate immune system, researchers have found many kinds of antigen-presenting cells, which are essential for activating and activating the adaptive immune system, as well as natural killer cells (attacking virus infected cells and tumor cells).other innate immune cells known as neutrophils (only in the inflamed sites) are found in postnatal infants, but not in fetuses.the team also found a large number of B cells and T cells in the fetal gut, which are part of the adaptive immune system.Image Source: developmental cell surprisingly, most T cells are "memory" type, helping the body remember past invaders so that they can respond to repeated attacks more quickly in the future.konnikova said: "the discovery of memory T cells is completely unexpected because they need to be exposed to pathogens to form, and the traditional view is that the placenta prevents most pathogens from entering the uterus."she speculated that the fetus might be exposed to the molecular by-products of pathogens floating in amniotic fluid, and the fetus began swallowing amniotic fluid as early as 12 weeks. microscopic images showed memory T cells in the fetal small intestine (left) and large intestine (right). Image Source: Cell Press / konnikova lab researchers believe that a large number of memory T cells can provide some initial protection against microbial attack at birth and prevent over activation. konnikova pointed out that there are several points to note in this study: the immune system of the gut may not reflect the immune system of other tissues; fetal tissue is limited to the second trimester of pregnancy; neonatal tissue is not obtained from completely healthy infants. in the future, researchers plan to study what kind of environment the fetal immune system is exposed to in the uterus and whether it can be controlled to benefit the developing fetus. konnikova said they hope to monitor or control the immune system before birth, which may help diagnose diseases or develop beneficial maternal vaccines at an early stage of fetal development.