Long Covid study reveals key insights into a possible cause

Long Covid study reveals key insights into a possible cause

Scientists have identified a persistent change in a handful of blood proteins in people with long Covid, suggesting that an important part of their immune system remains on high alert for months after a severe infection.

Experts say the findings, published Thursday in the journal Science, could help explain the causes of persistent fatigue, brain fog and other debilitating symptoms of long Covid, as well as pave the way for diagnostic tests and perhaps a long-awaited treatment.

The study followed 113 coronavirus patients for up to a year after they were first infected, along with 39 healthy people. Six months later, 40 patients developed long Covid symptoms.

Repeated blood samples showed important differences in their blood: A group of proteins indicated that part of the body’s immune system called the complement system remained active long after it had returned to normal.

Dr. Honor Boyman, professor of immunology at the University of Zurich in Switzerland and one of the study authors, said: “When you have a viral or bacterial infection, the complement system becomes active and binds to these viruses and bacteria and then eliminates them.” Investigators. He added that the system then returns to a resting state, where its normal function is to clean the body of dead cells.

But if the complement system remains in an antimicrobial state after eliminating viruses and bacteria, it “starts damaging healthy cells.”

He continued: “These could be endothelial cells lining the inner layers of blood vessels, cells in the blood itself, and cells in different organs, such as the brain or lungs.” The result is tissue damage and tiny blood clots.

Previous studies have documented blood clotting and tissue damage in people with long Covid. “But this research addresses the molecular mechanism of how this starts,” said Akiko Iwasaki, a professor of immunobiology and molecular, cellular and developmental biology at Yale University School of Medicine, who was not involved in the new study.

Tissue damage combined with blood clots can lead to disabling symptoms of long Covid, including exercise intolerance.

During exercise, the heart pumps more blood and moves endothelial cells inside blood vessels, which are found everywhere in the body, Boyman said.

“In healthy people, normal endothelial cells can take on these changes, but inflamed endothelial cells in long Covid patients cannot,” he said.

Iwasaki noted that microclots can reduce the level of oxygen and nutrients delivered to various organs.

“If your brain, for example, isn’t getting enough oxygen, obviously there’s going to be a lot of issues with memory and brain fog and fatigue,” she said.

A potential path to tests and treatments

Just over 14% of U.S. adults reported having experienced long Covid, according to the latest data from the U.S. Census Bureau’s Household Pulse Survey.

Dr. Monica Verduzco Gutierrez, chief of rehabilitation medicine at the University of Texas Health Science Center at San Antonio and head of the long COVID clinic, praised the new study.

“Understanding the mechanisms of long Covid is how we will discover treatments,” she said.

Verduzco-Gutierrez, Iwasaki, and Boyman agree that the new research points the way toward developing diagnostic tests and treatment by focusing on proteins of the complement system.

However, Boyman and his colleagues used sophisticated and sophisticated methods to detect differences in these proteins that cannot be used in a routine diagnostic laboratory.

“We need companies that are already active in diagnostics and have enough manpower and financial strength” to develop a simplified test, he said.

Once the test is developed, or through careful screening of long Covid patients, drug companies can begin clinical trials of potential treatments, Boyman said. He said drugs already exist to modulate and inhibit the complement system for very rare immune diseases affecting the kidneys, muscles or nervous system, and could be tested in long Covid patients.

New drugs could also be developed, Iwasaki said.

“I think there are a lot of things we can try in the future,” she said. She added: But first, the results of this study must be replicated, as is the case with any research.

Verduzco-Gutierrez said she would like to see any future studies that follow patients for a longer period of time. “What about people who have had long Covid for three years? “We don’t know what their blood looks like,” she said.

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