E3 PreliminaryPreliminaryPEM requiredReview-NarrativePeer-reviewedMachine draft
A review of cytokine-based pathophysiology of Long COVID symptoms.
Low, Russell N, Low, Ryan J, Akrami, Athena · Frontiers in medicine · 2023 · DOI
Quick Summary
This review examines how Long COVID may develop through a chain reaction of immune system problems. When the virus infects the body, it can trigger ongoing inflammation that affects both the immune system and the brain, potentially causing blood clots in small vessels. This combination may explain symptoms like fatigue, brain fog, and pain that Long COVID and ME/CFS patients experience.
Why It Matters
This study is significant because it provides a unifying biological framework connecting Long COVID and ME/CFS, two conditions with substantial symptom overlap but historically separate research bases. Understanding shared inflammatory and microglial mechanisms could accelerate development of targeted treatments and improve patient care for both conditions. The emphasis on cytokine dysregulation offers testable hypotheses for future mechanistic studies.
Observed Findings
- Symptom overlap between Long COVID and ME/CFS includes fatigue, post-exertional malaise, brain fog, joint pain, and dysautonomia
- Chronic low-grade inflammation with dysregulated peripheral immune activation has been documented in Long COVID cohorts
- Microglial activation and central nervous system cytokine release have been proposed as mechanisms for neuroinflammatory symptoms
- Immunothromobsis and microclot formation may contribute to tissue perfusion deficits and ischemia
- Genetic polymorphisms in cytokine genes may influence individual susceptibility to chronic inflammation
Inferred Conclusions
- SARS-CoV-2 infection can trigger a self-perpetuating cycle of dysregulated immunity, chronic inflammation, and neuroinflammation that produces Long COVID symptoms
- Genetic and epigenetic factors may determine whether acute COVID-19 progresses to chronic Long COVID or ME/CFS-like illness
- Shared pathophysiological mechanisms suggest Long COVID and ME/CFS may represent related conditions on a disease spectrum
- Targeting cytokine cascades and p38 MAP kinase pathways may offer therapeutic opportunities for both conditions
Remaining Questions
- What specific genetic polymorphisms and epigenetic modifications predispose individuals to chronic inflammation following SARS-CoV-2 infection?
What This Study Does Not Prove
This review does not establish causality or validate the proposed pathways through original experimental or clinical data—it synthesizes existing literature into a theoretical model. The study does not prove that cytokine dysregulation is the primary driver of Long COVID symptoms, nor does it demonstrate that all Long COVID patients follow this particular pathophysiological trajectory. The connection between Long COVID and ME/CFS progression remains speculative and requires prospective clinical investigation.
Tags
Symptom:Post-Exertional MalaiseCognitive DysfunctionOrthostatic IntolerancePainFatigueSensory SensitivityTemperature Dysregulation
Biomarker:CytokinesGene ExpressionBlood Biomarker
Phenotype:Infection-TriggeredLong COVID Overlap
Method Flag:Exploratory Only
Metadata
- DOI
- 10.3389/fmed.2023.1011936
- PMID
- 37064029
- Review status
- Machine draft
- Evidence level
- Early hypothesis, preprint, editorial, or weak support
- Last updated
- 10 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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