Petrov et al. (2026)
- Authors: Steliyan Petrov, Martina Bozhkova, Mariya Ivanovska, Teodora Kalfova, Dobrina Dudova, Yana Todorova, Radostina Dimitrova, Mariana Murdjeva, Hristo Taskov, Maria Nikolova, Michael Maes
- Institutes: Department of Medical Microbiology, Medical University of Plovdiv, Plovdiv, Bulgaria, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria, Sichuan Provincial Center for Mental Health, University of Electronic Science and Technology of China, Chengdu, China
- Publisher: medRxiv
- Link: DOI
Summary
This study identifies distinct immune landscapes for ME/CFS and Long COVID, demonstrating that they are biologically divergent conditions despite sharing similar clinical symptoms. The research highlights that while Long COVID is marked by persistent immune activation and exhaustion, ME/CFS is characterized by immune suppression and impaired cell movement. These findings are significant for developing objective diagnostic biomarkers and personalized treatment strategies for both patient populations.
What was researched?
The study performed extensive immunophenotyping of monocyte subsets and dendritic cells to compare the biological signatures of ME/CFS and Long COVID. It aimed to determine if these conditions share a common pathophysiology or represent distinct immunological states.
Why was it researched?
Despite overlapping symptoms like fatigue and cognitive dysfunction, the underlying mechanisms of ME/CFS and Long COVID remain poorly defined. Differentiating these conditions is essential for improving diagnosis and ensuring patients receive appropriate, targeted medical care.
How was it researched?
Researchers used multiparameter flow cytometry to analyze blood samples from 207 participants, including 103 patients with ME/CFS, 63 with Long COVID, and 41 healthy controls. Advanced statistical methods, including principal component analysis (PCA) and correlation network analysis, were applied to identify complex immune patterns.
What has been found?
Long COVID was associated with increased M2-like monocyte polarization and expanded dendritic cell populations, signaling chronic activation and immune exhaustion. In contrast, ME/CFS was characterized by reduced expression of costimulatory molecules and impaired CCR7-mediated immune cell trafficking, indicating a state of immune suppression.
Discussion
The study’s strength lies in its large cohort and the use of integrated network analysis to reveal distinct pathophysiology. However, the researchers noted that as a preprint, these findings require peer review and validation in larger independent cohorts.
Conclusion & Future Work
The research concludes that ME/CFS and Long COVID are driven by different immunopathological mechanisms. These unique immune signatures provide a foundation for developing diagnostic tools to distinguish between the two conditions.