The recent news cycle has been dominated by discussions surrounding Covid-19, with a specific focus on the subset of patients exhibiting severe symptoms. Emerging research implies that these individuals might be experiencing what is coined as “Cytokine Storm Syndrome” (CSS). CSS is characterized as an excessively strong immune response, typically triggered by viral infections. Severe COVID-19 patients are identified by symptoms like respiratory failure that necessitates mechanical ventilation and shock, or organ failure demanding intensive care, both of which can result in fatalities.
Understanding Cytokine Storm Syndrome and the Immune Response
The role of our immune system in bolstering our health cannot be overstated. It serves as our first line of defense against various bacteria, viruses, and parasites infiltrating our bodies. Getting activated by foreign entities or antigens such as bacteria, fungi, and viruses, the immune system begins its process of elimination.
A healthy immune response is usually accompanied by inflammation, an essential part of the remedial process. Inflammation visibly manifests when one sustains an injury — for instance, the redness and swelling around a hurt knee or ankle. The immune system dispatches white blood cells to the damaged area to commence repair work. Without this innate immune response, any bodily harm would never fully heal, and infections could turn lethal.
The Function and Impact of Cytokines
Cytokines are inflammatory immunological proteins that combat infections and ward off cancerous growths. Their release promotes increased blood flow to the aggravated area, allowing an abundance of immune system cells to reach the damaged tissue and therefore expediting the healing process. While inflammation plays a crucial role as a protective mechanism, if it goes unchecked, it can lead to dire consequences—inducing a ‘cytokine storm’.
Cytokine Storm Syndrome (CSS) occurs when there’s an overproduction of immune cells and cytokines due to a dysregulated process. This can materialize due to an infection, an auto-immune condition (where the body’s immune system mistakenly attacks healthy cells, as seen in coeliac disease), or other diseases. Its symptoms include high fever, inflammation, extreme fatigue, and nausea.
During any flu infection, a cytokine storm is associated with a surge of activated immune cells into the lungs. However, instead of eliminating the antigen, this results in lung inflammation, fluid build-up, and subsequent respiratory distress.
Dangers Posed by an Excessive Immune Reaction
A severe immune reaction leading to an over-secretion of cytokines can be harmful. The surfeit of immune cells might start attacking healthy tissue, potentially causing severe damage and even death. This could also lead to sepsis, a critical condition that transpires when the body’s response to infection triggers changes that can harm multiple organ systems.
CSS Observations in Covid-19
Though Cytokine storms are not exclusive to Covid-19 patients, they are a common immune reaction during other infectious and non-infectious diseases as well. CSS is suspected to be a significant cause of mortality during the 1918-20 Spanish Flu, the H1N1 (swine flu), and H5N1 (bird flu) outbreaks.
Increased pro-inflammatory cytokine responses against coronaviruses such as SARS-CoV-1, SARS-CoV-2 (which is responsible for the current COVID-19 pandemic), and Middle East Respiratory Syndrome (MERS) can result in acute lung injury and Acute Respiratory Distress Syndrome (ARDS). If these clinical features of CSS are not identified and properly treated promptly, they can result in multiple organ failure. Researchers have suggested that all severe COVID-19 patients should be screened for hyperinflammation to ensure better and timely treatment.