Scientists have identified persistent changes in a handful of blood proteins in people with long-term coronavirus infections. This indicates that important parts of the immune system remain on high alert for months after an acute infection.
of findingsA paper published Thursday in the journal Science could help explain the cause of persistent fatigue, brain fog and other debilitating symptoms caused by long-term COVID-19 infections, and could help explain diagnostic tests and other debilitating symptoms. In some cases, it could pave the way to long-awaited treatments, experts say.
The study followed 113 coronavirus patients and 39 healthy controls for up to a year after initial infection. At six months, 40 patients developed long-term coronavirus symptoms.
Repeated blood samples were taken and it was discovered that there were important differences in their blood. A group of proteins showed that a part of the body's immune system called the complement system remains activated long after it should have returned to normal.
“When you are infected with a virus or bacteria, the complement system is activated and binds to and eliminates these viruses and bacteria,” says Onur, a professor of immunology at the University of Zurich in Switzerland and one of the participants in the study.・Dr. Boyman said. Investigator. The system then returns to a dormant state and its normal job is to remove dead cells in the body, he said.
But if the complement system continues to fight off microbes even after viruses and bacteria have been eliminated, “it starts to damage healthy cells,” he says.
“These could be endothelial cells lining blood vessels, cells from the blood itself, or cells from various organs such as the brain or lungs,” he continued. As a result, tissue is damaged and microscopic clots form in the blood.
Previous studies have documented blood clotting and tissue damage in people with long-term coronavirus infections. “But this study gets into the molecular mechanisms of how that happens,” says Professor of Immunobiology and Molecular, Cellular, and Developmental Biology at Yale School of Medicine, who was not involved in the new study. said Akiko Iwasaki.
Tissue damage and blood clots can lead to disabling symptoms of long-term COVID-19 infection, such as exercise intolerance.
Boyman says that during exercise, the heart pumps more blood, stirring up endothelial cells in blood vessels throughout the body.
“In healthy people, normal endothelial cells can tolerate these changes, but inflamed endothelial cells in long-term coronavirus patients cannot,” he said.
Professor Iwasaki pointed out that microcoagulation can reduce the levels of oxygen and nutrients delivered to various organs.
“For example, it's clear that if your brain doesn't get enough oxygen, you'll have a lot of problems with memory, brain fog, fatigue, etc.,” she says.
Potential routes to testing and treatment
More than 14% of U.S. adults report having previously experienced a long-term COVID-19 infection, according to the latest data. U.S. Census Bureau Household Pulse Survey.
Dr. Monica Verduzco Gutierrez, director of rehabilitation medicine and longtime head of the coronavirus clinic at the University of Texas Health Science Center in San Antonio, praised the new study.
“By understanding the mechanisms of long-lasting coronavirus, we can find treatments,” she says.
Verduzco-Gutierrez, Iwasaki and Boyman agree that the new research points the way to developing diagnostic tests and treatments that focus on proteins of the complement system.
But to detect differences in these proteins, Boyman and his colleagues used a complex, state-of-the-art method not available in routine diagnostic laboratories.
To develop a rapid test, “we need companies that are already working on diagnostics and have sufficient human resources and financial resources,” he said.
Boyman said drug companies could begin clinical trials of potential treatments once tests are developed or rigorous screening of patients with long-term COVID-19 infections is achieved. . Drugs that modulate or inhibit the complement system in extremely rare immune disorders that affect the kidneys, muscles and nervous system already exist and could be tested in patients with long-term COVID-19 infections. He said that there is.
New drugs may also be developed, Iwasaki said.
“I think there are a lot of things I can try in the future,” she said. But, she added, as with her other studies, the results of this study first need to be replicated.
Verduzco-Gutierrez said she hopes future studies will follow patients over a longer period of time. “What happens to people who have been infected with coronavirus for three years? We don't know what their blood is like,” she said.
