Researchers have long sought explanations for persistent symptoms after COVID-19 infection. A study co-led by Akiko Iwasaki and published in CELL reports that some people with long COVID produce autoantibodies that bind to brain and peripheral nerve tissues. These autoantibodies frequently targeted areas involved in pain signalling, memory, balance, sensory processing and autonomic nervous system control, which could explain complaints such as brain fog, dizziness, headaches, fatigue, burning pain and numbness.
The team analysed blood from people with long COVID, healthy volunteers and recovered individuals without lasting symptoms. They purified antibodies and exposed them to human and mouse tissues, finding stronger reactivity from long COVID samples. The researchers also screened the samples against more than 21,000 human proteins and identified many targets related to neurons, neurotransmission, inflammation and hormone signalling.
To test causality, antibodies from long COVID patients were transferred into healthy mice. The recipient animals developed increased pain sensitivity, fatigue, impaired balance and damage to small nerve fibres, and collaborators observed abnormal neuronal activation in brain regions linked to pain, fatigue, memory and emotional regulation. The authors say the findings suggest overlap with autoimmune disease and could point toward treatments already used for some autoimmune conditions, but they emphasise that further study of the neurological and immunological mechanisms is required. Contributors include teams from Yale, Mount Sinai, the Howard Hughes Medical Institute and other institutions.
Difficult words
- autoantibody — an antibody that attacks the body's own tissuesautoantibodies
- peripheral — relating to the outer parts of the nervous system
- signal — the process of sending information between nerve cellssignalling
- autoimmune disease — a condition where the immune system attacks self
- neuron — a nerve cell that transmits signals in the brainneurons
- neurotransmission — the process by which nerve cells send chemical signals
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Discussion questions
- What are the possible benefits and risks of using existing autoimmune treatments for people with long COVID?
- How do the results from the mouse experiments support or limit the idea that antibodies cause long COVID symptoms?
- What further studies or observations would help clarify the neurological and immunological mechanisms described in the article?
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