How Autoimmune Responses in the Brain Could Explain Long COVID Symptoms

Medical News: A team of researchers from the University of Electronic Science and Technology of China, Chulalongkorn University in Thailand, Medical University of Plovdiv-Bulgaria, Kyung Hee University-Korea and Immunosciences Lab, Inc-USA, recently released a study that brings fresh insights into the lingering effects of COVID-19, specifically in individuals experiencing what is commonly known as "Long COVID." With millions worldwide affected by symptoms that persist months after their initial COVID-19 infection, this research helps to explain why some people face chronic fatigue, anxiety, depression, and cognitive issues long after their recovery.


How Autoimmune Responses in the Brain Could Explain Long COVID Symptoms

Their research focuses on autoimmunity - when the body’s immune system mistakenly attacks its own tissues - as a possible cause of these symptoms. The team has examined antibodies that may be targeting specific proteins in the brain, potentially explaining the neurological and psychiatric symptoms seen in Long COVID. This Medical News report will detail the study findings and the implications they hold for understanding and potentially treating this complex condition.
 
The Connection Between Long COVID and Autoimmunity
For many who have survived COVID-19, the illness doesn't simply end with a negative test result. The aftermath, known as Long COVID, brings with it a range of symptoms that can last from months to years. These symptoms often mirror those seen in chronic fatigue syndrome (CFS) and mood disorders, such as depression and anxiety, creating a complex syndrome that affects both the body and mind. The research team’s aim was to explore if an autoimmune response targeting the brain might explain these persistent issues.
 
In this study, researchers examined blood samples from 90 individuals with Long COVID and 90 healthy control subjects, comparing levels of antibodies - immune proteins that identify and neutralize foreign substances. They paid particular attention to antibodies directed at brain proteins, hypothesizing that these could provide clues to the chronic symptoms experienced by Long COVID patients. Additionally, they measured antibodies related to viral infections, such as human herpesvirus-6 (HHV-6), to explore if these infections might be reactivated and contributing to the immune response.
 
Key Findings: Immune Attack on Brain-Associated Proteins
The study's results are striking, showing that individuals with Long COVID have significantly elevated levels of antibodies targeting certain brain proteins, compared to healthy individuals. The antibodies they measured include IgG, IgA, and IgM, each playing a unique role in the immune response. High levels of antibodies like IgG-tubulin and IgM-BBD (associated with brain and blood-brain barrier proteins) suggest that Long COVID may involve an immune response that mistakenly targets parts of the central nervous system.
 
The researchers identified that specific antibodies - particularly IgG and IgM directed against myelin bas ic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) - were reliable predictors of Long COVID. These proteins are essential for maintaining the myelin sheath, which insulates nerves and allows for fast, efficient communication between nerve cells. When these proteins are attacked, it can lead to nerve damage and potentially contribute to symptoms like brain fog and impaired cognitive function.
 
Using advanced statistical models, the researchers found that autoimmune responses against MBP and MOG, along with inflammation markers like C-reactive protein (CRP) and advanced oxidation protein products (AOPP), could predict the severity of fatigue and mood-related symptoms in Long COVID sufferers. This connection between brain-targeted autoimmunity and symptoms like chronic fatigue and anxiety provides a new understanding of how the immune system might be driving Long COVID symptoms.
 
How These Findings Connect to Other Diseases
Autoimmune diseases are not new; they’re involved in various chronic conditions, from rheumatoid arthritis to multiple sclerosis. In fact, the brain-targeted immune responses observed in Long COVID patients are reminiscent of other neuro-immune conditions. For instance, increased antibodies against brain proteins have also been observed in individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and certain psychiatric disorders. The researchers also noted that specific autoantibodies targeting brain proteins are found in other neuro-immune diseases, suggesting that Long COVID might share mechanisms with these conditions.
 
In other words, Long COVID could involve autoimmune responses similar to those seen in well-established autoimmune and neuro-inflammatory conditions. For instance, antibodies against the protein synapsin, which is essential for proper neuronal communication, have been linked to mood and cognitive disturbances. These findings strengthen the possibility that Long COVID could be a type of autoimmune condition with neurological impacts, not merely a viral infection that persists.
 
Predicting Long COVID Symptoms with Antibody Levels
An exciting element of this research is the team’s use of predictive modeling to understand Long COVID symptoms. Using artificial neural network analysis, they examined how antibody levels could predict the severity of symptoms like chronic fatigue and mood disturbances. Their findings revealed that certain antibodies - such as IgM-synapsin and IgG-MBP - could predict the intensity of mood-related symptoms with about 80% accuracy. This kind of modeling could pave the way for diagnostic tools that use biomarkers to better identify individuals at risk for Long COVID and to potentially tailor treatments based on immune profiles.
 
By analyzing antibody levels and inflammatory markers, the study offers a method to not only diagnose Long COVID but also determine the likely severity of symptoms. This is significant for individuals struggling with the condition, as it suggests that blood tests measuring specific immune markers could one day be used to guide treatment decisions and symptom management.
 
Understanding Long COVID as a Neuro-Autoimmune Condition
The most compelling part of the study is its proposal that Long COVID symptoms might result from a neuro-autoimmune response. According to the authors, when the immune system mistakenly targets proteins in the brain, it could lead to lasting damage that manifests as chronic fatigue, brain fog, depression, and other symptoms. The study’s authors suggest that, similar to multiple sclerosis, Long COVID could involve an attack on the nervous system that disrupts normal brain function.
 
The study also found a correlation between high body temperature during the acute COVID-19 infection phase and the later development of autoimmune responses against brain proteins. This means that the severity of the initial COVID-19 infection might influence the likelihood of developing Long COVID symptoms. Persistent viral infections and the reactivation of dormant viruses, such as HHV-6, could also be contributing factors in triggering these autoimmune responses.
 
Conclusions and Implications for Future Research
This study is a significant step forward in understanding Long COVID as a condition with potentially long-lasting immune effects on the brain. By identifying specific antibodies that target brain proteins and linking them to chronic symptoms, this research provides a foundation for developing diagnostic tools and treatments tailored to the immune responses of Long COVID patients.

Future research could build on these findings by further exploring the role of these antibodies in causing neurological symptoms. Additionally, the study suggests that therapies aimed at modulating the immune response could benefit Long COVID patients, potentially helping to manage or reduce the severity of their symptoms.
 
The study findings were published in the peer-reviewed Journal of Advanced Research.
https://www.sciencedirect.com/science/article/pii/S2090123224005307
 
For the latest COVID-19 News, keep on logging to Thailand Medical News.
 
Read Also:
https://www.thailandmedical.news/news/covid-19-poses-long-term-risks-for-autoimmune-disorders
 
https://www.thailandmedical.news/news/singapore-case-study-reveals-that-even-mild-covid-19-can-trigger-fatal-liver-failure-in-patients-with-autoimmune-liver-disease
 
https://www.thailandmedical.news/news/avacopan-offers-new-hope-for-patients-battling-the-deadly-autoimmune-disease-called-anca-associated-vasculitis