When we get sick we trust our immune system to protect us, but what happens when that system goes awry and ends up killing patients? COVID-19 is shedding new light on how viruses can kick some patient’s immune system into overdrive to deadly effect, what is known as a cytokine storm syndrome (CSS).
In short, our immune system by and large is incredibly effective at working around the clock to keep a myriad of infections and diseases at bay, while, simultaneously being able to identify between outside invaders and our own cells and effectively prioritize what to attack and what to protect. However, occasionally, either due to genetic factors or rampant viral infections like COVID-19, our immune system can become overzealous and go rogue, thus, attacking and killing everything in sight, including healthy cells in the body. When that happens it is referred to as a cytokine storm and it may be killing around half of severe COVID-19 patients.
Cytokines are inflammatory immunologic communication proteins that are there to fight off infections and ward off cancers, but, when they are out of control, they can make you very ill. As there are many types of immune cells, when they sense any foreign invader they starts communicating by releasing cytokines in order to activate immune system for fight against any foreign particle. Depending on immune cells there are many types of cytokines e.g. IL’s, TNF etc. every immune cell of immune system releases these proteins for communication with other cells.
Our immune systems are far from simple and have a number of safe guards to keep invaders out. This can be broken down into our IIS (innate immune system) and our AIS (active immune system), which contributes to our adaptive immune response, as well as our passive immune system, which is “borrowed” from another source and lasts for a short time
The innate immune system response relies on the use of physical barriers like our skin and mucous membranes, coupled with our first responder defenders like phagocytes, antimicrobial proteins, and attack cells. The innate immune system response is why, for example, we get a stuffy nose and sneeze when we have a cold, or why a scrapped knee gets red, hot and inflamed, as well as sometimes filled with pus.
By and large, this first defense is effective, and maybe why those people who contract COVID-19 are asymptomatic. However, when the innate immune system isn’t enough it calls on our second line of defense; the active immune system. This is typically when the inflammatory response gets kicked into a higher gear and you develop a fever, which triggers a number of your body’s chemical alarms that call the active immune system to action and increases the metabolic rates in cells, thus allowing them to heal faster, as well as making it easier for a variety of immune response cells and proteins to do their jobs faster and more effectively. This is also when people start feeling body aches associated with COVID-19 and other viral infections.
The active immune response is both complex and elegant and not only identifies and fights off viruses like COVID-19, it also remembers these viruses so it can quickly and effectively combats and neutralize them in the future, thus creating immunity. This is why vaccines are one of the more amazing developments of modern medicine.
IS Cytokine storm responsible for the death of COVID-19 patient?
Viruses like COVID-19 have a devious trick up their sleeve when it comes to making us sick; in a sense, they use human cells to shelter and reproduce. When COVID-19 is searching the body for a cellular host to attach to it is fairly exposed and it is easier for our active immune response to target and kill them. COVID-19 wants to do three things when it enters our body; find protection, reproduce and spread.
Our cells offer the perfect environment for COVID-19 to do all three. So COVID-19, which targets the respiratory system, attaches and infiltrates our respiratory cells where it can more effectively hide from our immune system early on and reproduce. The infected cell will then spit out more of the COVID-19 virus that will repeat the process. This is where the battle royale of our immune response kicks off with our cellular immune response.
Our body has a special cell called the T-Cell, which has a variety of forms that it exists in to combat infection. When T-Cells are activated they release cytokines which trigger additional T-Cells to be made, which then release even more cytokines. One type of T-cells that are created is called cytotoxic T-cells. Cytotoxic T-cells are the cells that are able to roam the body and mercy kill infected cells who are chemically calling out to be killed and ideally to stop the increased production of viruses like COVID-19.
When your body responds the way it is supposed to, the cytotoxic T-cells will only target infected cells to be killed and move along. Additionally, the immune response also has a chemical indicator that ideally tells overzealous immune response cells to stand down once the threat has been neutralized.
It is when we are in the throes of a cytokine storm that those systems start to get overwhelmed and malfunction. In essence, our body’s immune response gets so amped up that it stops differentiating between infected and healthy cells and attacks everything in its path. For obvious reasons, this is very bad for patients because not only is the COVID-19 virus killing the cells in our bodies, now our immune system is too.
There are also a few effective treatments for cytokine storms despite the fact that we still do not know exactly which treatments will ultimately be developed and recommended across the board for COVID-19 related cytokine storms. There’s always kind of this push pull between doing no harm and trying therapies that haven’t been tried for this disease because it’s new to mankind.