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| Small study finds an inflammatory cytokine called Interleukin 6 (IL-6) could play a role in "long Covid." (Wikipedia illustration) |
Kentucky Health News
A small study has found that severe cases of Covid-19 can lead to lasting changes in the human immune system, the first line of defense against germs entering the body.
The finding could explain why Covid-19 can damage so many different organs and why some people with "long Covid" have high levels of inflammation.
The study, published in the peer-reviewed journal Cell, examined immune cells and molecules in blood samples from 38 people recovering from severe Covid-19, others who had recovered from other severe illnesses, and 19 healthy people.
The researchers also used a new technique to collect rare blood-forming stem cells that circulate in the blood, eliminating the need to extract such cells from bone marrow. A news release describes those rare stem cells as the parents of immune-system cells.
What they found in examining those rare stem cells was that there were changes in them that led to an increased production of immune cells, called monocytes, and that these changes were passed on to "daughter cells" and ultimately resulted in the increased production of molecules called "inflammatory cytokines," compared to healthy people or those with non-Covid-19 illnesses.
The Cleveland Clinic defines cytokines as "signaling proteins that help control inflammation in your body" and says, "too many cytokines can lead to excess inflammation and conditions like autoimmune diseases."
The release says "The researchers observed these changes as much as a year after the participants came down with Covid-19."
While the small sample size did not allow the researchers to make a direct association between the cellular and molecular changes in those rare stem cells and health outcomes, the release said the researchers suspect that an an inflammatory cytokine called IL-6 might play a role in the changes in the rare stem cells.
The researchers tested their hypothesis both in mice with Covid-19-like disease and in people with Covid-19 and found that blocking IL-6 early in the disease process with antibodies reduced altered gene expression in stem cells and the production of monocytes and inflammatory cytokines during recovery, compared to the subjects that didn't receive the antibody. This also resulted in less organ damage in mice.
The release notes that these findings suggests that the changes in the innate immune system caused by Covid-19 may last long after the illness is over. The findings could also lead to new therapeutic approaches to treat long Covid. Also, they underscore the importance of vaccination.
"The results also underscore the importance of staying up to date with recommended Covid-19 vaccines, which are proven to protect against serious illness, hospitalization and death," says the release.
The study was led by Steven Z. Josefowicz of Weill Cornell Medicine in New York City and funded by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.
