Australian researchers have discovered that coronavirus can spawn molecular storms that damage patients' hearts.
But QIMR Berghofer scientists have also identified a class of drugs that could potentially guard against heart damage, or even reverse it.
The team has been delving into exactly how COVID-19 damages the heart.
It's important because a growing body of research suggests up to two-thirds of patients who've recovered from severe COVID-19 experienced some heart inflammation.
And about a quarter of patients hospitalised with severe COVID-19 suffered some form of cardiovascular injury.
The researchers have found that in severe cases, the immune system overreacts to the infection.
The result is a flood of inflammatory molecules, called cytokines, into the bloodstream. It's this so-called "cytokine storm" that can damage organs including the heart.
The researchers used lab-grown, human heart organoids - miniaturised, simplified versions of an organ - in their work.
They wanted to find out exactly how cytokine storms damage the heart, identify the proteins responsible, and then repurpose existing drugs that target those proteins.
When they exposed the organoids to blood from COVID-19 patients, they found it caused dysfunction even when the virus didn't infect the tissue itself.
"These experiments revealed which inflammatory factors are potentially causing the cardiac problems," said Associate Professor James Hudson, who heads QIMR Berghofer's Cardiac Bioengineering Research Group.
"These factors activate bromodomain protein 4 in the heart, which we found was the key driver of cytokine storm damage."
The researchers then used their mini heart organoids to screen existing drugs that inhibit this protein and found they can prevent and reverse the damage.
Apabetalone is one of them.
Canadian biotechnology company Resverlogix was already conducting clinical trials of the drug to treat cardiovascular disease.
It will now also look at whether it can improve the clinical status of patients with COVID-19 and treat heart damage.
Prof Hudson said that because the drug is already in phase three clinical trials, it could be available sooner to treat COVID-19 patients.
There was also another important finding.
Tests showed apabetalone reduces the expression of the receptor protein ACE2, found on the cell surface and used by the COVID-19 to infect cells.
That led to a lower viral infection, which in turn decreased heart damage in lab experiments.
Australian Associated Press