Karisola et al. (2025)
- Authors: Piia Karisola, Mari Kanerva, Aki Vuokko, Helena Liira, Shuyuan Wang, Kirsi Kvarnström, Mikko Varonen, Hille Suojalehto, Harri Alenius
- Institutes: Human Microbiome (HUMI) Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland, Department of Infection Control, TYKS Turku University Hospital, Turku, Finland, Outpatient Clinic for Long-Term Effects of COVID-19, Helsinki University Central Hospital, Helsinki, Finland
- Publisher: Frontiers in Immunology
- Link: DOI
Summary
This study demonstrates that for most patients with Post-COVID Condition (PCC), persistent symptoms are not mirrored by major changes in blood gene expression. However, the identification of a specific male subgroup with altered red blood cell signatures provides a biological clue for a distinct disease mechanism. These findings suggest that PCC is a heterogeneous condition where different biological pathways, such as oxygen transport issues, may drive symptoms in different patient subsets.
What was researched?
The study investigated whether patients with Post-COVID Condition (PCC) exhibit specific gene expression changes in their blood cells that correlate with their persistent symptoms.
Why was it researched?
Researchers sought to understand the underlying molecular mechanisms of Long COVID and whether patients can be grouped into distinct biological subtypes based on their transcriptomic signatures.
How was it researched?
The cohort included 54 PCC patients, 57 recovered patients, and 63 healthy controls. Researchers performed transcriptomic analysis (RNA-seq) on peripheral blood cells and used cellular deconvolution to estimate the proportions of different immune cell types.
What has been found?
Overall, PCC patients showed only minimal transcriptomic differences compared to controls. However, a specific subgroup of men with PCC exhibited a significant increase in immature red blood cells (erythroblasts) and 399 differentially expressed genes. These genes were primarily involved in heme metabolism and gas exchange processes in erythrocytes.
Discussion
The results indicate that Long COVID symptoms are multifactorial and often exist without widespread changes in blood cell gene activity. The discovery of the male-specific erythrocyte signature suggests that oxygen delivery and red blood cell health may be critical factors for some patients.
Conclusion & Future Work
The study concludes that PCC is highly complex and likely involves various biological drivers. Future research should investigate if the observed erythrocyte changes in men contribute to symptoms like fatigue and exercise intolerance.