Shahbaz et al. (2026)
- Authors: Shima Shahbaz, Najmeh Bozorgmehr, Amirhossein Rahmati, Amal Abouda, Hussain Syed, Mohammed Osman, Shokrollah Elahi
- Institutes: University of Alberta, Edmonton, AB, Canada
- Publisher: Frontiers in Immunology
- Link: DOI
Summary
This study provides a high-resolution map of immune dysfunction in Long COVID, distinguishing it from traditional ME/CFS and offering a path toward targeted therapies. By identifying specific cell types and molecular pathways that fail to return to baseline after 12 months, it validates the biological reality of the condition. The discovery of potential biomarkers like Galectin-9 could eventually lead to objective diagnostic tests, reducing the stigma and clinical uncertainty for those suffering from post-viral illnesses.
What was researched?
The research investigated the cellular and molecular immune profiles of female individuals suffering from Long COVID who met the diagnostic criteria for ME/CFS one year after infection. The study aimed to define the specific immune remodeling and exhaustion markers that distinguish this condition from full recovery and idiopathic ME/CFS.
Why was it researched?
The biological mechanisms driving Long COVID-associated ME/CFS are poorly understood, making diagnosis and treatment difficult. Identifying the specific immune cells and signaling pathways involved is essential for finding therapeutic targets and clinical biomarkers.
How was it researched?
Researchers performed single-cell RNA sequencing (scRNA-seq) on peripheral blood mononuclear cells from patients 12 months post-infection. They compared these findings to recovered individuals and utilized public datasets to contrast the results with idiopathic (non-COVID) ME/CFS patients.
What has been found?
The study found a significant reduction in naïve T cells, regulatory T cells, and specialized immune cells like MAIT and γδ T cells in Long COVID patients. NK cells exhibited impaired cytotoxic potential, while monocytes showed a pro-inflammatory skew and reduced ability to clear debris. Notably, the Galectin-9–TIM-3 interaction was identified as a key driver of specific T cell depletion, a feature less pronounced in idiopathic ME/CFS.
Discussion
The findings suggest that Long COVID-associated ME/CFS is characterized by more extensive immune exhaustion and remodeling than idiopathic ME/CFS. A limitation of the study is its small, female-only cohort, which reflects the group most affected but may not fully represent male immune responses.
Conclusion & Future Work
Long COVID-associated ME/CFS is driven by chronic immune activation and profound cellular dysregulation. The researchers conclude that Galectin-9, Artemin, and Reelin are promising candidates for diagnostic biomarkers and potential therapeutic intervention.