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Classic pathway persistent complement activation is associated with specific symptoms in individuals with
César Fernández-de-Las-Peñas1, Maria Ruiz-Ruigómez2, Laura Esparcia-Pinedo3
1Department of Physical Therapy, Occupational Therapy, Physical Medicine and Rehabilitation, Universidad Rey Juan Carlos (URJC), Madrid, Spain; Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
This study found no overall complement activation in COVID-19 survivors with post-COVID-19 condition. However, specific symptoms like fatigue and dyspnea were linked to lower levels of certain complement proteins.
Area of Science:
- Immunology
- Infectious Diseases
- Clinical Medicine
Background:
- The complement system is a key immune component, but its role in post-COVID-19 condition remains unclear.
- Investigating complement activation may offer insights into the pathophysiology of long-term COVID-19 symptoms.
Purpose of the Study:
- To investigate long-lasting complement hyperactivation in COVID-19 survivors with and without post-COVID-19 condition.
- To determine if complement pathway activation is associated with the presence of specific post-COVID-19 symptoms.
Main Methods:
- A case-control study (2:1 design) compared COVID-19 survivors with and without post-COVID-19 condition.
- Blood samples were analyzed for classical complement pathway proteins (C3, C4, C5, C7) and total hemolytic complement (CH50) activity.
- Post-COVID-19 condition was defined by self-reported symptoms including fatigue, arthralgia, myalgia, memory problems, headache, or palpitations.
Main Results:
- No significant differences in overall complement protein levels or CH50 activity were found between groups.
- Patients with post-COVID fatigue showed lower C3 levels compared to those without fatigue.
- Survivors with post-COVID dyspnea exhibited lower levels of C3, C5, and C7 proteins.
Conclusions:
- This study did not find evidence of overall classical complement pathway activation in COVID-19 survivors with post-COVID-19 condition up to two years post-infection.
- Specific complement proteins were associated with particular post-COVID-19 symptoms, suggesting a nuanced role in the condition.
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