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Source: Global Science
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The cells use an extraordinary "trick", and they can also slightly activate immune defense when they are not infected.This includes using "false viruses".
In childhood, if you dont want to go to school, this may be a seemingly clever plan: splashing hot water on his face, walking into the kitchen, sending out the angel cryingThe pain moan.Your hot forehead is enough to convince your parents to help you ask you the last sick leave.
But no matter how meticulous you plan, how realistic you are, your persuasiveness is always unsatisfactory.However, the latest research published in the "Cell Host & Amp; Microbe" magazine stated that the human body and other mammals in development will use a similar strategy to make more convincingPerformance.
This research shows the placenta -embryo organs connecting mothers and fetuses -how to use a "scam" on a molecule to pretend to be sickof. By pretending to be attacked by the virus , the placenta keeps the immune system at a gentle and stable amplitude to prevent the internal fetus from quietly escape the virus attack of the mothers immune system.
This discovery proposed that before being infected, certain cells may be able to activate the immune system slightly to provide appropriate protection for fragile tissues.
Cells to activate the immune defense response in a precedent, "largely violates one of the views held by immunologists," a one from Poporton Childrens Hospital and Harvard Medicine in the United States and Harvard Medical MedicineJonathan Kagan, an immunologist in the hospital, said that he did not participate in this research).
Kagan said that immune weapons against virus may damage normal tissue, so cells usually activate them only when infection appears. When the virus infection is cleared, these weapons will be turned off as soon as possible.
But, according to this research, the placenta broke this rule.For some reason, the placenta opens the defense system and keep it working when it does not need to be defensive. At the same time, it does not hurt itself or a fetus.
" It is protected, but it does not hurt ," Associate Professor-Hana Totory-Jain said, "evolution is so smart."
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01
Placenta pretend to be sick
Tetari-Jia Yin accidentally found the pricardial deception method.She and her laboratory members in the placenta were a huge gene cluster that was expressed in the placenta- "a monster," she said.She was surprised to find that, in addition to activating genes that promote placental development, the gene cluster also activated an immune signal protein called interferon λ. Why is it activated in a healthy and infected cells?Tetari-Jia Yinhes team took many years of energy to find this answer: Placental cells take out RNA from their own genome and make a one with it.The structure that is very similar to the virus is to deceive the immune sensor (Immune Sensors).
The genome records our evolutionary history.Since the moment of life on the earth, the virus has begun to insert genetic material into their hosts DNA.In the middle of the genes encoding protein, these relics of these ancient microorganisms are invasive.
△ Hana Tetari Jiayin, associate professor of molecular pharmacology at the University of Tanpan Florida, found that placenta cells used a kind of usePseudo -virus to cunning the immune system (source: USF Health Morsani College of Medicine)
One of the most common virus elements retained in the human genome is a group ofDNA called Alu repeated sequence. ALU constitutes at least 13%of the human genome; it has more than 300 copies in the huge gene clusters of Tota-Jiayin.She guessed that these ALU repeatedly turned on the switch of the placenta immune system.But her colleague warned her not to go deep in this direction.
"I have received such suggestions:‘ Do n’t contact ALU, do n’t study alu, forget alu ’," said Tota Li Jia Yin.The existence of ALU in the genome makes it difficult for people to analyze the role of a specific group.
However, the data involved in ALU is too strong, so that it cannot be ignored.After several years of detailed experiments, the team of Tetari-Jia Yin pointed out that in the placenta, the transcript of the alu repeated sequence forms a dual-chain RNA fragment- a kind of identification by its own cell as a source of viruses virus sourcesThe molecular structure. After the false virus was detected, the cells produced interferon λ.
"The cells dressed as a pathogenic source in a effective way," Jia Yin said."As a result, It not only made itself infected, but also operated according to this.
02
The immunity of "fermentation" slightAnti -virus reaction.Because the virus is the most dangerous when it is in the cell, , the most antivirus immune strategy will kill the infected cells to a certain extent.
Therefore, when the cells call for "virus!" In most organizations, the ALU sequence is highly suppressed so that they cannot simulate a virus attack -and this is a scene that placenta intentionally wants to cause.How can it balance the potential danger of the healthy development and immune response of the embryo?
In the mouse experiment, the team of Tetari Jiayin found that the placentas dual-chain DNA and the stimulating immune response seemed to not hurt the developmental embryo.Instead, they protect the embryo from infection with Zika virus.Placental cells honestly abide by the rules -the immune response that does not cause damage to its own when protecting the embryo - Because the interferon λ they summon can implement a more mild defense .
Generally speaking, the "RNA fugitive" that first responds to the dual -chain ALU is type Ⅰ and Ⅱ interferon Sexual immune cells are collected in the infection, causing tissue injury and even autoimmune diseases.However, interferon λ is a III interferon.It only transmits signals with local tissue cells, caused a gentlest and more immune response that can be kept in the placenta for a long time .
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It is still a mystery to keep the immune response ease without excessive active.However, Tetari-Jia Yin put forward an explanation why only the placental cells evolved in this strategy (other cells tried to avoid): placenta will be thrown away at birth, so it can bear certain immune risks, it can bear certain immune risks.Other cells cannot.
The results of this research reveal the new strategy of protecting the fetus except for the mothers immune system.During pregnancy, in order to prevent the mother from attacking the embryonic cells different from her own genes, the immune response of the mothers body was weakened, and therefore the placenta had to perform additional defense on the developed fetus.
However, this "trick" -low -intensity immune response caused by pseudo -virus -perhaps not only limited to the placenta.Recently, researchers from Columbia University described a similar phenomenon that exists in neurons.They observed that the RNA, which derives from different genome elements, will be combined into a double chain, causing an immune response.In this case, the immune system summons more destructive type Ⅰ interferon, but the amount generated is very small.The author speculates that The long -term low -degree inflammatory response in the brain may control the infection to prevent large inflammation and neuron death.
It can be seen from this that this kind of immune trick is more common than we think .By studying how the immune system breaks its own rules, scientists can better define the original rules of life.
https://www.quantamagazine.org/during-pregnancy-a-face-infection-petus-20231114/
