The Science Behind Cytokine Storms

 Whilst doing some further reading around the Coronavirus, I saw the phrase ‘cytokine storm’ mentioned in pretty much every article about the potential implications of contracting Covid-19. So, what is a cytokine storm? What causes it? How is it controlled?

To put it simply, a cytokine storm is an exaggerated and dangerous immune response, in which the immune system is producing too many inflammatory signals that can lead to multiple organ failure and even death. Relating this back to the current pandemic, cytokine storm seems to be a part of the reason some patients develop fatal symptoms from Covid-19.

Let’s start by defining a ‘cytokine’. Cytokines are a group of proteins secreted by cells of the immune system that act as chemical messengers. These proteins are released from one cell and affect the actions of other cells by binding to receptors on their surface. There are many different types of cytokines, such as interferons and chemokines, but ultimately, the role of cytokines is to help regulate the immune response. Some help produce inflammation, whilst others help restrict the body’s inflammatory response.

Why can this be so dangerous? When the body produces too many inflammatory cytokines and not enough that moderate inflammation, the result in an overwhelming cytokine response. People hospitalised in the ICU with Covid-19 seem to have elevations in several inflammatory cytokines; this has been linked to the development of acute respiratory distress syndrome – the leading cause of death in people with Covid-19. 

What causes this exaggerated immune response? It is not fully understood what causes a cytokine storm, but certain underlying health conditions are thought to play a role. People with certain genetic or autoimmune syndromes are predisposed to experiencing a cytokine storm, but a more common causing factor is infection, including those caused by viruses, bacteria and other agents. Even though in this case, most people fortunately don’t experience a cytokine storm, some infections are more likely to cause it than others – for example SARS-CoV-2 appears more prone to result in a cytokine storm.

How can it be controlled/treated? In some situations, treating the underlying source of the cytokine response, clears up the storm itself. Unfortunately, in many cases direct treatment for the underlying cause is not possible. Other approaches to tackle this immune response are complicated since so many factors and processes feed into the whole immune response. Many different therapies are currently being investigated, especially in light of the coronavirus.

Sources:

·       https://study.com/academy/lesson/what-are-cytokines-definition-types-function.html

https://www.verywellhealth.com/cytokine-storm-syndrome-4842383#:~:text=An%20Exaggerated%20and%20Dangerous%20Immune%20Response&text=Cytokine%20storm%20syndrome%20refers%20to,to%20organ%20failure%20and%20death.