E2 ModeratePreliminaryPEM not requiredCross-SectionalPeer-reviewedMachine draft
Long COVID: Association of Functional Autoantibodies against G-Protein-Coupled Receptors with an Impaired Retinal Microcirculation.
Szewczykowski, Charlotte, Mardin, Christian, Lucio, Marianna et al. · International journal of molecular sciences · 2022 · DOI
Quick Summary
Some people with Long COVID have abnormal immune proteins called autoantibodies that attack blood vessel control systems in their bodies. This study found that patients with these specific autoantibodies had reduced blood flow in the tiny vessels at the back of the eye, which may reflect similar problems throughout their whole body and could explain some of their symptoms.
Why It Matters
This study provides potential mechanistic insight into Long COVID pathophysiology by linking autoimmune markers to measurable microvascular dysfunction, a finding highly relevant to ME/CFS research given the overlap in post-viral symptom patterns and proposed microvasculature involvement in both conditions.
Observed Findings
- Patients with Long COVID had significantly impaired macular and peripapillary vessel density compared to controls.
- Autoantibodies targeting β2-adrenergic receptors showed significant association with reduced vessel density.
- Autoantibodies targeting MAS, AT1, and α1-adrenergic receptors were significantly linked to impaired microcirculation.
- Female patients demonstrated more pronounced decreases in vessel density than males.
- Seropositivity for GPCR-AAbs was documented in Long COVID patients using cardiomyocyte bioassay.
Inferred Conclusions
- Functional GPCR-AAbs in Long COVID may contribute to or be associated with impaired retinal capillary microcirculation.
- Retinal microvascular changes detected by OCT-angiography may serve as a non-invasive marker of systemic microcirculatory dysfunction in Long COVID.
- Sex differences in the association between GPCR-AAbs and microvascular impairment suggest potential hormonal or biological sex modifiers of autoimmune-mediated vascular dysfunction.
Remaining Questions
- Does impaired retinal vessel density directly cause or contribute to Long COVID symptoms such as fatigue, cognitive dysfunction, or orthostatic intolerance?
- Are GPCR-AAbs pathogenic drivers of microvascular dysfunction or merely biomarkers of prior infection?
What This Study Does Not Prove
This study does not prove that GPCR-AAbs cause the microvascular dysfunction—correlation alone cannot establish causality. It does not demonstrate that retinal vessel changes necessarily reflect systemic microcirculation deficits or directly cause clinical symptoms, nor does it establish whether these autoantibodies are pathogenic or simply markers of prior infection.
Tags
Biomarker:AutoantibodiesBlood Biomarker
Phenotype:Infection-TriggeredLong COVID Overlap
Method Flag:Small SampleExploratory OnlySex-Stratified
Metadata
- DOI
- 10.3390/ijms23137209
- PMID
- 35806214
- Review status
- Machine draft
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 8 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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