An overactive inflammatory response could be at the root of many long Covid cases, according to a new study.
Looking at proteins circulating in the blood, the scientists from the Allen Institute and Fred Hutchinson Cancer Center in the US, found a set of molecules associated with inflammation that were present only in a subset of patients with long Covid and were not seen in those who recovered from their disease.
Out of 55 patients with long Covid, about two-thirds had persistently high levels of certain signals of inflammation.
The scientists also looked at blood samples from 25 people who had Covid but recovered, and from 25 volunteers who had never had Covid to their knowledge. Those without long Covid did not show the same signs of inflammation in their blood.
Scientists have seen previous links between inflammation and long Covid, but the new study, published in the journal Nature Communications, is the first to trace the persistence of these inflammatory markers over time in the same patients.
There’s an obvious implication to these findings, said Troy Torgerson, Director of Experimental Immunology at the Allen Institute for Immunology.
Certain kinds of anti-inflammatory drugs might alleviate symptoms for some long Covid patients. But physicians need a way of telling which long Covid patients might benefit from which treatment.
“The big question was, can we define which long Covid patients have persistent inflammation versus those that don’t? That would be useful in terms of clinical trial planning and in terms of helping clinicians figure out targeted treatments for their patients,” said Torgerson.
Specifically, the blood markers uncovered in this subset of patients with “inflammatory long Covid,” as the scientists call it, point to a flavour of inflammation similar to that seen in autoimmune diseases like rheumatoid arthritis.
This kind of inflammation can be treated with an existing class of drugs called JAK inhibitors, at least in the case of rheumatoid arthritis (it has not yet been tested for long Covid).
The scientists also hope to narrow down their molecular signature of “inflammatory long Covid” to a few markers that could be used in the clinic to sort this subset of long Covid patients out from the rest.
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