What is cytokine storm?
Cytokines, an umbrella term for a number of different molecules, are small proteins released by cells; they are cell-signaling molecules in the glial nervous system cells, which play the role of messengers. Cytokines play a very important role in the immune system.
Cytokine storm, also called cytokine release syndrome or hypercytokinemia, is a condition that consists of an immune reaction involving a positive feedback loop between immune cells and cytokines. To explain this more simply, cytokine storm occurs when the body is flooded with the release of too many cytokines in a short period of time.
Cytokine storm is a potentially fatal reaction, associated with high death rates during pandemics of flu. The term “storm” is used because the system overacts to an intruder, for example a virus, and all the cells responsible for the immune reaction start working in an exaggerated manner. The reaction is so strong that it can seriously harm the entire system, leading to multiple organ failure, becoming life-threatening, and potentially leading to a fatal outcome.
Cytokine storms are more likely to occur in young, strong individuals, who have a stronger immune system. Fortunately, cytokine release syndrome is not a common condition and it is mainly seen in intensive care unit patients with severe sepsis.
The symptoms of cytokine storm are similar to those seen when the body is dealing with an severe infection — a high fever, redness, swelling, inflammation, nausea, vomiting, extreme fatigue and such.
Causes of cytokine storm
When a pathogen, such as a virus, enters the body, cytokines signal specific immune cells, for example T-cells and macrophages, to go to the infection site and fight the pathogen. Not only that — cytokines also activate those cells to more cytokines are produced. Normally, the immune system keeps this loop at a desired level.
In cytokine storm, which occurs for reasons that are not completely clear, the reaction blasts beyond control and too many immune cells get activated. This can cause significant damage to tissues and organs.
A cytokine storm can occur as a complication of many diseases, such as chickenpox, bird flu, sepsis, systemic inflammatory response disease, graft versus host disease and others. COVID-19 can cause cytokine storm, as well, potentially leading to death.
Before that, cytokine storms were responsible for a higher number of deaths in certain pandemics, such as the 1918 flu pandemic, when an unusually large number of healthy young adults died from influenza, or the SARS epidemic in 2003.
Cytokine release syndrome can also be caused by certain types of immunotherapy medications.
Treatment for cytokine storm syndrome
There are several options for treating cytokine storms. One of them is OX40 immunoglobulin. ACE inhibitors and angiotensin II receptor blockers are being investigated as a potential therapy for this serious condition.
Corticosteroids and non-steroidal anti-inflammatory drugs have both traditionally been used in the treatment of cytokine storms, but in clinical trials investigating their role in cytokine storms associated with acute respiratory distress syndrome, they showed little or no positive effect.
Gemfibrozil, which is an agent that suppresses the production of pro-inflammatory cytokines, is currently being tested on lab animals. Other options include free radical scavengers and TNF-alpha blockers.