Every minute, 250 babies are born in the world. For their families, it is an extraordinary event. For scientists, birth is the result of a fact that implies a captivating paradox: the woman's immune system is dedicated to defending her against the invasion of viruses, bacteria, fungi, among others, but allows the development of a fetus which contains genetic material from another person. Now scientists from England, Spain and Germany have first introduced themselves the atlas of the cells that are in the zone of contact between the placenta and the woman during the first months of pregnancy. In this way, they corroborated the existence of molecular mechanisms that make the woman's immune system "friendly" with the presence of the fetus.
O atlas with 35 cell types It was published by researchers in a paper journal Nature of Great Britain. They got him to study 70,000 white blood cells and cells from the placenta and decidua (the layer that forms in the pregnant uterus), which came from women whose pregnancies ended between weeks 6 and 14 of gestation that gave their consent. in writing.
The identification of these types of cells and the molecular mechanisms that occur in the interaction between the maternal immune system and the fetus provide more knowledge to understand the causes of the different problems that may arise during pregnancy. "It can be said that there are several mechanisms to ensure a friendly environment between the fetal and maternal cells," he said. Infobae the first author of the book, the Spanish biotechnologist Roser Vento-Tormos, who is doing postdoctoral studies in the laboratory of scientist Sarah Teichmann at the Sanger Institute in Cambridge, UK.
Days after the egg is attached to the sperm, the blastocyst, which is implanted in the womb of the woman. The placenta is also formed in the decidua, which is the mucous covering the uterus transiently. There, the fetal and maternal cells make contact. Traditionally it was considered that the fetus was like a graft within the woman, but thanks to the advancement of the field of research in pregnancy immunology everything has changed. The atlas – which was also carried out by researchers at YDEVS Software Development in Valencia, Spain, the Cancer Research Center in Heidelberg, Germany, and the universities of Cambridge and Newcastle in England – took another step at that address.
"In our study, we observed that cells located in the layer adjacent to the placenta express immunomodulatory molecules, and that, therefore, reduce any type of inflammation that can be created by invasion of fetal cells which form the basic structure of the placenta, and invade the uterus, "Vento-Tormos said.
The fetus has its own cells that help the mother's immune system not to attack it. They are the trophoblasts, which are the main components of the placenta. "In one of the pathways of differentiation, trophoblasts differentiate and invade the decidua and go to the arteries, where they replace maternal endothelial cells and swell the arteries, which is crucial for increasing blood flow to the placenta and therefore , the change of nutrients between the fetus and the mother. Along the way they will meet and communicate with the maternal immune cells.. This very specific communication, which we describe in detail in our article, contributes to the fact that fetal and maternal cells coexist in the same environment. In fact, our study suggests that the immune system may be necessary for the necessary invasion of the trophoblasts, "said Wind-Tormos.
With the atlas, we try to "see all the cells that exist in the microenvironment and how they communicate". I do not like using the word "tolerate", since the immune system is not asleep. The maternal immune system is active and has specific functions such as assisting in the remodeling of the arteries or helping fetal trophoblasts invade the tissue and go to the arteries. There is a specific communication between the trophoblasts and the maternal immune cells so that both cells interact in a peaceful way, "said the Spanish scientist.
"Currently there is a great deal of interest in knowing what the mediators and mechanisms of the" dialogue "or interaction between the placenta and the mother's immune system are in early pregnancy. Understanding these mechanisms at the cellular and molecular level could contribute to the development of early treatments for gestational complications that are diagnosed until the end of pregnancy, such as preeclampsia and restriction of fetal growth, which can have serious consequences for maternal and newborn health, "he said. Infobae Claudia Pérez Leirós, Conicet's principal investigator at IQUIBICEN, Faculty of Exact and Natural Sciences, University of Buenos Aires, who along with Dr. Rosanna Ramhorst leads a research group specialized in reproduction immunology. Pre-eclampsia disorder can affect up to 5% of pregnant women, alters blood pressure and causes the death of 76,000 women a year in the world (25% of these deaths occur in Latin America).
"The atlas published in the journal Nature It is very valuable, "said Dr. Pérez Leirós, describing the different cell populations present at the maternal-fetal interface in early pregnancy and indicates their possible interactions through a new technology to study the RNA of cells at the individual level, which is called a transcriptomic and a bioinformatic analysis.As the authors shared the data obtained in a public repository, certainly this wealth of information will be used by researchers from other laboratories, and will contribute to accelerate studies related to pregnancy and associated pathologies.
In addition to the pregnancy-related pathologies, the first trimester atlas of pregnancy could also provide clues to better understand what happens to the immune system when the body receives an organ transplant from another person, or when the tumors develop. "The environment during pregnancy and cancer has similarities," said Roser Wind-Tormos. "In both scenarios, cells with different DNA coexist. Cancer cells are different because of mutations that accumulate in the DNA. Even so, they have mechanisms to evade the immune response, just as fetal trophoblasts do. In this environment, we detected the presence of immunological checkpoint inhibitors similar to those occurring in cancer. "