The immune system of patients with post-COVID produces antibodies that may play a role in the development of their symptoms. In this case, the body’s own immune system fails and mistakenly turns against itself. This is indicated by a study led by researchers from Amsterdam UMC and UMC Utrecht. The results of the study pave the way for the development of new treatments, such as targeted therapies that can remove or neutralize harmful antibodies.
Post-COVID syndrome is a condition that affects more than 10 percent of people after infection with the coronavirus. It causes a wide range of symptoms, including extreme fatigue, pain, post-exertional malaise (PEM), and cognitive impairments (“brain fog”).
Dysregulation
Little is known about the cause. Previous studies had already pointed to a dysregulation of the immune system and the presence of antibodies that mistakenly target the body’s own tissues (autoantibodies). The researchers wanted to investigate whether they could find evidence in mice that these antibodies indeed cause the symptoms. It is already known that antibodies from patients with other diseases with similar symptoms, such as fibromyalgia, can also induce symptoms in animals.
Antibodies from patients’ blood
In the study, researchers administered antibodies, derived from the blood of 34 patients with post-COVID, to mice. The result was striking: the animals developed chronic symptoms of pain and discomfort that lasted at least two weeks. Even more remarkable was that antibodies collected from the same patients two years later still caused the same symptoms in mice. Researcher Niels Eijkelkamp (Center for Translational Immunology, UMC Utrecht) explains: “This result suggests that the underlying disease mechanism persists long after the initial infection, which may explain why many patients experience long-term symptoms.”
Different biological causes
To better understand the condition, researchers analyzed blood samples from patients with post-COVID. This allowed them to distinguish different patient subgroups. When antibodies from these different groups were tested in mice, they also produced different patterns of symptoms. Researcher Jeroen den Dunnen (Center for Infection and Molecular Medicine, Amsterdam UMC) adds: “This finding supports the idea that post-COVID syndrome is not a single, uniform condition, but a heterogeneous disease with different biological causes.”
Present in the blood for years
The team also discovered that antibodies from patients with post-COVID target the body’s own proteins involved in various functions, such as nerve activity and cellular metabolism. Many of these autoantibodies remained measurable in the blood for years and differed between specific patient subgroups.
This study has limitations, including the small number of patients involved. “However,” both researchers note, “three independent research groups have recently reported similar findings, which strengthens confidence in the idea that autoantibodies contribute to post-COVID syndrome.”
Targeted therapy
The results therefore provide clues for new treatment strategies, such as therapies that can remove or neutralize harmful antibodies and thereby reduce symptoms. For example, immunotherapy aimed at specific patient subgroups.
This study is an important step toward understanding and potentially treating post-COVID. Meanwhile, researchers continue to unravel the complexity of this chronic and often debilitating condition.
Read more about the full study in the scientific journal Cell Reports Medicine.
Source: Amsterdam UMC