What is a cytokine storm? – By Amber Dance – Apr 2020
As Covid-19 cases fill the hospitals, among the sickest and most likely to die are those whose bodies react in a signature, catastrophic way.
- Immune cells flood and attack the lungs they should be protecting.
- Blood vessels leak;
- the blood itself clots.
- Blood pressure plummets and
- organs start to fail.
Such cases, doctors and scientists increasingly believe, are due to an immune system gone overboard — so that it harms instead of helps.
Variants on this hyperactive immune reaction occur in an array of conditions, triggered by infection, faulty genes or autoimmune disorders in which the body thinks its own tissues are invaders
All fall under the umbrella term “cytokine storm,” named because substances called cytokines rampage through the bloodstream.
Here’s what scientists know about cytokine storms and the part they play in Covid-19.
When the cytokines that raise immune activity become too abundant, the immune system may not be able to stop itself.
Most patients experiencing a storm will have a fever, and about half will have some sort of nervous system symptoms, such as headache, seizures or even coma
Cytokine storm in Covid-19
Physicians in Wuhan, in a study of 29 patients, reported that higher levels of the cytokines IL-2R and IL-6 were found in more severe Covid-19 infections.
Another team, analyzing 150 cases in Wuhan, found that an array of molecular indicators for a cytokine storm — including IL-6, CRP and ferritin — were higher in those who died than in those who survived.
Cytokine storms are also raging among US patients.
“I’ve seen plenty of it,” says Roberto Caricchio, chief of rheumatology at Temple University in Philadelphia.
Precise data aren’t in yet, but he says that a “sizable fraction” — perhaps 20 to 30 percent — of patients with severe cases and lung symptoms have signs of a cytokine storm.”
“Covid is — maybe — a relatively unique cytokine storm,” Cron says.
Blood-clotting rates seem to go beyond those often seen in other storm conditions, but ferritin levels don’t rise to quite the same sky-high levels. In Covid-19, doctors may observe immune cells attacking the lungs so early, and so harshly, that a sort of scar tissue called fibrosis forms. “It seems to happen quickly with this virus.”
five of the patients looked at by Cron and colleagues carried mutations in a gene called LYST, which causes defects in trafficking of cellular garbage. This disrupts the activity of perforin and prevents immune cells from responding properly to invaders.
It’s possible, Cron says, that these or similar mutations might explain why about 20 percent of people get a severe or critical version of Covid-19, while others have milder symptoms or even no symptoms at all.
Taming the storm
Steroids are often the first choice of treatment. They act broadly to dampen the immune system
In the case of Covid-19, it’s not yet clear if steroids are beneficial or harmful, Cron says.
There are also medications that interfere with specific cytokines. If steroids are an atom bomb, these drugs are targeted missile strikes.
Researchers are initiating several clinical trials of cytokine blockers for Covid-19.
But for any treatment to work, doctors must catch the storm happening.
Cron recommend that everyone sick enough to be hospitalized with Covid-19 get an inexpensive test for ferritin in their blood.
Interim guidelines from the US Centers for Disease Control and Prevention, updated April 3, mention that high CRP and ferritin levels may be correlated with more severe illness;
Author: Amber Dance has been working from home since 2008. www.AmberLDance.com