What is "cytokine storm"? Why can it suddenly aggravate the disease?

On January 24, the first clinical data report of sars-cov-2 infection cases published by the lancet pointed out that cytokine storm can be seen in critical patients [1] China's novel coronavirus pneumonia is also an important node in the new crown pneumonia patients' mild to severe and critical illness, and is also a cause of severe and critical death, Zhou Qi, academician of the Chinese Academy of Sciences, said recently So what's this annoying "cytokine storm"? How does it add novel coronavirus pneumonia? Before we talk about cytokine storms, let's take a look at what cytokines are As the security guard of human body, the immune system relies on a huge and complex immune network composed of immune cells to play its immune function How does the complex regulatory relationship of cells regulate information transmission? Thanks to their "liaison officer" - cytokines Under normal circumstances, the circulation of the immune system is progressive and regressive When the invasion of foreign pathogens and the aging of their own cells, the immune system often starts the immune stress mechanism Immune cells will release pro-inflammatory cytokines (including interferon (IFN), interleukin (IL), tumor necrosis factor (TNF), etc.) while removing these harmful substances, so as to call on more immune cells to join the war against foreign enemies At the same time, these immune cells will also secrete more cytokines, so as to continuously expand the war force, thus forming a positive and negative war force Feed When the immune system finally controls the invading pathogen, the cytokines will be reduced, and then the inflammatory response will be weakened Therefore, appropriate and coordinated cytokine release can timely mobilize a large number of immune cells to reach the infection site, inhibit infection and eliminate pathogens However, when the immune system is over activated due to infection, drugs, autoimmune diseases and other factors, the immune cells will be over stressed and produce too many cytokines to aggravate the inflammation A large number of secreted pro-inflammatory factors will cause the positive feedback cycle to break through a certain threshold and enlarge, and eventually form a cytokine storm At this time, the liaison officer becomes a traitor and the anti terrorist elite becomes a terrorist The immune system, which is fully open and uncontrolled, is equivalent to an uncontrolled air attack, which indiscriminately attacks all cells, including pathogens, and then causes systemic inflammation, multiple organ failure and even death Taking this pneumonia as an example, some experts think that the continuous increase of neutrophils in some severe and dead patients may be caused by the cytokine storm induced by the virus So to some extent, the damage of cytokine storm to human body is even greater than that of virus itself 。 In addition to the new coronavirus, many studies have shown that cytokine storm is also an important killer of SARS, H1N1, Ebola and other infectious diseases [2-4] Since cytokine storm is so severe, what should we do to deal with it? At present, some immunosuppressants are often used in clinic to regulate cytokine storm, so that the immune response in the body is in a normal range, which can not only kill the virus, but also the normal tissue cells In the national novel coronavirus pneumonia diagnosis and treatment plan (trial version fifth), the treatment of critically ill patients includes glucocorticoid treatment, and points out that we should pay attention to the immunosuppressive effect of large doses of glucocorticoids, which will delay the removal of coronavirus Therefore, in the process of clinical treatment for cytokine storm, we should pay attention to the control and slowing down of cytokine storm response, at the same time, we should also accurately grasp the dosage of drugs, to avoid excessive inhibition of immune response caused by excessive dosage It can be seen that the most important thing for immunity is balance Immunity is too weak, vulnerable to external virus and bacteria, too strong and easy to "kill 800 enemies and self damage 1000" " As the direction of disease, immune imbalance can not only monitor our autoimmune status, but also effectively indicate the risk of disease Many research results have shown that the immune system and the development of a variety of diseases have important significance [6-8] Therefore, it is of great significance to periodically evaluate our immune balance Based on the complexity and systematization of immune cells, it is necessary to evaluate not only the proportion of many immune cells, but also the dynamic balance of the system action modes among immune cells.