Discover groundbreaking research revealing the prolonged activity of the immune system in long COVID patients. Explore how targeting complement system proteins may lead to diagnostic breakthroughs and potential treatments. Stay informed on the latest developments in understanding and addressing lingering symptoms with expert insights from renowned immunologists.
Long COVID
Scientists suggest that medications that calm a crucial part of the immune system should be studied in clinical trials as a potential treatment for long-term COVID-19.
Researchers have observed continuous changes in certain proteins in the blood of individuals who have been battling COVID for an extended period, indicating that a vital part of their immune system remains highly active for months after severe infection.
Symptoms Of Long COVID
Experts believe that the results published in Thursday’s journals could help explain the reasons behind prolonged fatigue, brain fog, and other lingering symptoms of long COVID, as well as pave the way for smoother diagnostic tests and potentially long-awaited treatments.
In this study, 39 healthy controls were followed for a year alongside 113 COVID-19 patients after their first infection. At the six-month mark, 40 patients exhibited signs of long-term COVID-19.
Repeated blood samples revealed a significant difference in their blood. A group of proteins hinted at the persistent activity of a part of the immune system called the complement system, which remains active for an extended period after the usual recovery.
Dr. Honoré Boekhout, a professor of immunology at the University of Zurich in Switzerland and an honorary doctor in the study, explained, “When you have a viral or bacterial infection, the complement system gets activated and engages with these viruses and bacteria, and then eliminates them.” Afterwards, the system returns to its regular state, where its routine work is to clear dead cells from the body.
However, if the complement system remains fighting after eliminating viruses and bacteria, “it starts damaging healthy cells,” he said. These special cells, called endothelial cells, are like the connectors inside our blood vessels. They link the insides of the vessels, our blood cells, and cells in different organs, such as the brain and lungs. The result is damage to blood vessels and microclots in the blood.
Previous studies have documented damage to blood vessels and tissues in long-term COVID patients. Dr. Akiko Iwasaki, a professor of immunobiology and molecular, cellular, and developmental biology at the Yale School of Medicine, explained that this research focuses on the molecular mechanism of how this process could initiate, which was not addressed in previous studies.
Damage to blood vessels by microclots could lead to symptoms of debilitation in long-term COVID, including intolerance to exercise.
Boyman explained that during exercise, the heart pumps more blood, mobilizing the endothelial cells containing complement system proteins throughout the blood vessels, which are present throughout the body.
He said, “In healthy individuals, common endothelial cells can undergo these changes, but in long COVID patients, endothelial cells capable of swelling cannot.” Iwasaki noted that microclots can reduce the supply of oxygen and nutrients to various organs, affecting the functioning of the brain, for example.
“A lack of sufficient oxygen to your brain, for example, will lead to problems with memory, brain fog, and fatigue,” she said.
A Potential Path for Testing and Treatment
According to the latest figures from the U.S. Census Bureau’s Household Pulse Survey, more than 14% of adults in the United States have experienced long COVID at some point.
Dr. Monica Verduzco-Gutierrez, head of physical medicine and rehabilitation at the University of Texas Health Science Center San Antonio and head of the Long COVID Clinic, praised the new research.
She said, “Understanding the mechanisms of long COVID is how we are going to find ways to treat it.”
Other studies have also identified potential mechanisms. In a study published in the October issue of Cell Reports, researchers suggested that remnants of the virus in the intestines of long-term COVID patients activate the neurotransmitter serotonin. They suggested that low levels of serotonin could explain some neurological and cognitive symptoms.
In another study published in Nature in September, researchers found that cortisol levels were significantly lower in long-term COVID patients compared to both other COVID patients and healthy controls. Cortisol helps people stay alert and awake.
Verduzco-Gutierrez, Iwasaki, and Boyman agree that the new research points towards focusing on complement system proteins for diagnostic tests and treatment development.
However, Boyman and his colleagues used the latest and most complex methods that cannot be used in routine diagnostic laboratories.
“We need the involvement of existing companies in diagnostics, which have enough manpower and financial power,” he said so that an easy test can be developed.
Once a test is developed, or with the rigorous screening of long COVID patients, pharmaceutical companies could initiate clinical trials for potential treatments. Boyman said that already available medications that affect the complement system, known for affecting joints, muscles, or the nervous system, could be tested for their impact on long-term COVID patients.
Iwasaki suggested that new medications could also be developed.
“In my mind, there are many things we can test in the future,” she said. However, she emphasized the need to replicate the results of this study, as with any research, before moving forward.
Verduzco-Gutierrez said she would like to follow any future study on long-term patients for an extended period. What will happen to people who’ve been dealing with the long-lasting effects of COVID for three years? We don’t know how their blood will look,” she said.
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