Clinical evidence mounts that the leading cause of death in COVID-19 patients is the dangerous condition known as a cytokine storm.
In a recent study published in mBio, researchers found a protein in the blood that could be responsible.
They found that COVID-19 patients have much higher levels of a protein called galectin-9 in their blood.
Perhaps more importantly, they also found a positive correlation between the levels of galectin-9 and pro-inflammatory cytokines released in the blood, which can lead to a cytokine storm.
The study is from the University of Alberta. One author is Shokrollah Elahi.
In the study, the team analyzed the blood plasma of 120 patients with COVID-19. They found that levels of galectin-9 were much higher than in individuals with HIV and cancer.
The team had reported in the past that galectin-9 levels go up in HIV infection and with some cancers.
The findings suggest that galectin-9 levels in the body could be used as a biomarker to diagnose COVID-19 using a patient’s blood, potentially providing another non-invasive tool for COVID-19 testing.
The levels could also be used to indicate the severity of the disease, though further study on that aspect is required.
The discovery of elevated galectin-9 levels in COVID-19 patients is important because of the positive correlation between the protein and a wide range of pro-inflammatory cytokines.
Cytokines as small cell-signaling proteins are involved in checks and balances in the immune system; they can turn on or turn off some cells to regulate the immune system.
In the context of COVID, the problem is that there is a dysregulation of cytokine production—they are released very quickly in elevated levels. That’s what is called a ‘cytokine storm.’
The team found that galectin-9 is responsible for instructing immune cells to release the pro-inflammatory cytokines quickly in response to COVID-19 infection by binding to immune cells and forcing them to produce the cytokines.
Further, as tissues are damaged as a result of inflammation, more galectin-9 is released from the cells—which activates more immune cells and releases more cytokines in a vicious cycle.
The resulting cytokine storm damages tissue and organs causes severe inflammation and can lead to death.
Even if patients survive the storm, the dysregulation of the immune system can have ongoing consequences and could be associated with the condition known as a post-COVID-19 syndrome or long COVID.
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