The ME Association ME/CFS (& Long Covid) Weekly Research Round-up

May 28, 2021

The weekly research round-up now includes recent publications about ME/CFS and about Long Covid. We highlight several studies that have particularly caught our interest and follow these with the full list of publications together with their abstracts (summaries).

All research relating to ME/CFS can be located in the ME Association: Index of ME/CFS Published Research. It is a free resource and available to anyone.

This extensive library of research is normally updated at the end of each month, but with the change in staff, it will be updated again by 01 June 2021.

The Index provides an A-Z of published research studies, selected key documents and articles, listed by subject matter, on myalgic encephalomyelitis, myalgic encephalopathy, and/or chronic fatigue syndrome (ME/CFS).

You can use it to easily locate and read any research that you might be interested in regard to, e.g., epidemiology, infection, neurology, post-exertional malaise etc.

You can also find the Research Index in the Research section of the website together with a list of Research Summaries that provide more detailed lay explanations of the more interesting work that has been published to date.

ME/CFS Research Published 15 May – 21 May 2021 

Four new research studies on ME/CFS have been published during this period and we have also included 12 studies on Long Covid. We highlight two on ME/CFS from the selection below: 

The first study (1) reviews genetic research into fatigue which is an underlining symptom in many conditions. It examined RNA (molecules which help cells to create proteins) that are involved in a variety of functions, such as regulating the immune inflammatory reaction and participating in the development of fatigue by regulating mitochondria function and energy metabolism. 

The scientists investigated a number of different pathways in the gene regulatory network, suggesting fatigue is linked to one specific network pathway. It concluded that there is a need for more in-depth research into specific networks to understand the occurrence and development of fatigue and to find the key molecules involved. 

We will shortly be providing a research summary for the second study (2) that examined endothelial dysfunction in ME/CFS and used samples from the ME biobank. Findings could potentially provide biomarkers that could help in the diagnosis of ME/CFS. 

ME/CFS Research References and Abstracts 

1. Study on the Relationship between the miRNA-centered ceRNA Regulatory Network and Fatigue 

Yang X, Li F, Ma J, Liu Y, Wang X, Wang R, Zhang Y, Zhang W, He Q, Song D, Yu Journal of  Molecular Neuroscience. 2021 May 16. 


In recent years, the incidence of fatigue has been increasing, and the effective prevention and treatment of fatigue has become an urgent problem. As a result, the genetic research of fatigue has become a hot spot. Transcriptome-level regulation is the key link in the gene regulatory network.

The transcriptome includes messenger RNAs (mRNAs) and noncoding RNAs (ncRNAs). MRNAs are common research targets in gene expression profiling. Noncoding RNAs, including miRNAs, lncRNAs, circRNAs and so on, have been developed rapidly. Studies have shown that miRNAs are closely related to the occurrence and development of fatigue.

MiRNAs can regulate the immune inflammatory reaction in the central nervous system (CNS), regulate the transmission of nerve impulses and gene expression, regulate brain development and brain function, and participate in the occurrence and development of fatigue by regulating mitochondrial function and energy metabolism. 

LncRNAs can regulate dopaminergic neurons to participate in the occurrence and development of fatigue. This has certain value in the diagnosis of chronic fatigue syndrome (CFS). CircRNAs can participate in the occurrence and development of fatigue by regulating the NF-κB pathway, TNF-α and IL-1β.

The ceRNA hypothesis posits that in addition to the function of miRNAs in unidirectional regulation, mRNAs, lncRNAs and circRNAs can regulate gene expression by competitive binding with miRNAs, forming a ceRNA regulatory network with miRNAs. Therefore, we suggest that the miRNA-centered ceRNA regulatory network is closely related to fatigue.

At present, there are few studies on fatigue-related ncRNA genes, and most of these limited studies are on miRNAs in ncRNAs. However, there are a few studies on the relationship between lncRNAs, cirRNAs and fatigue. Less research is available on the pathogenesis of fatigue based on the ceRNA regulatory network. Therefore, exploring the complex mechanism of fatigue based on the ceRNA regulatory network is of great significance.

In this review, we summarize the relationship between miRNAs, lncRNAs and circRNAs in ncRNAs and fatigue, and focus on exploring the regulatory role of the miRNA-centered ceRNA regulatory network in the occurrence and development of fatigue, in order to gain a comprehensive, in-depth and new understanding of the essence of the fatigue gene regulatory network. 

2. Altered endothelial dysfunction-related miRs in plasma from ME/CFS patients 

Blauensteiner J, Bertinat R, León LE, Riederer M, Sepúlveda N, Westermeier F 
Scientific Reports 11, 10604 (2021). 


Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disease characterized by unexplained debilitating fatigue. Although the etiology is unknown, evidence supports immunological abnormalities, such as persistent inflammation and immune-cell activation, in a subset of patients.

Since the interplay between inflammation and vascular alterations is well-established in other diseases, endothelial dysfunction has emerged as another player in ME/CFS pathogenesis. Endothelial nitric oxide synthase (eNOS) generates nitric oxide (NO) that maintains endothelial homeostasis. eNOS is activated by silent information regulator 1 (Sirt1), an anti-inflammatory protein.

Despite its relevance, no study has addressed the Sirt1/eNOS axis in ME/CFS. The interest in circulating microRNAs (miRs) as potential biomarkers in ME/CFS has increased in recent years. Accordingly, we analyze a set of miRs reported to modulate the Sirt1/eNOS axis using plasma from ME/CFS patients.

Our results show that miR-21, miR-34a, miR-92a, miR-126, and miR-200c are jointly increased in ME/CFS patients compared to healthy controls. A similar finding was obtained when analyzing public miR data on peripheral blood mononuclear cells. Bioinformatics analysis shows that endothelial function-related signaling pathways are associated with these miRs, including oxidative stress and oxygen regulation. Interestingly, histone deacetylase 1, a protein responsible for epigenetic regulations, represented the most relevant node within the network.

In conclusion, our study provides a basis to find endothelial dysfunction-related biomarkers and explore novel targets in ME/CFS.  

3. European Network on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (EUROMENE): Expert Consensus on the Diagnosis, Service Provision, and Care of People with ME/CFS in Europe 

Nacul L, Authier FJ, Scheibenbogen C, Lorusso L, Helland IB, Martin JA, Sirbu CA, Mengshoel AM, Polo O, Behrends U, Nielsen H, Grabowski P, Sekulic S, Sepulveda N, Estévez-López F, Zalewski P, Pheby DFH, Castro-Marrero J, Sakkas GK, Capelli E, Brundsdlund I, Cullinan J, Krumina A, Bergquist J, Murovska M, Vermuelen RCW, Lacerda EM.  
Medicina. 2021; 57(5):510 


Designed by a group of ME/CFS researchers and health professionals, the European Network on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (EUROMENE) has received funding from the European Cooperation in Science and Technology (COST)—COST action 15111—from 2016 to 2020.

The main goal of the Cost Action was to assess the existing knowledge and experience on health care delivery for people with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in European countries, and to enhance coordinated research and health care provision in this field.

We report our findings and make recommendations for clinical diagnosis, health services and care for people with ME/CFS in Europe, as prepared by the group of clinicians and researchers from 22 countries and 55 European health professionals and researchers, who have been informed by people with ME/CFS. 

4. The effects of non-invasive vagus nerve stimulation on immunological responses and patient reported outcome measures of fatigue in patients with chronic fatigue syndrome, fibromyalgia, and rheumatoid arthritis 

Traianos E, Dibnah B, Lendrem D, Clark Y, Macrae V, Slater V, Wood K, Storey D, Simon B, Blake J, Tarn J, Ng WF 
Annals of the Rheumatic Diseases 2021;80:1057-1058. 


Background: Fatigue is reported as a common symptom among autoimmune and other chronic diseases such as fibromyalgia (FM), a long-term condition with uncertain pathophysiology. Previous studies from our group suggest that non-invasive vagus nerve stimulation (nVNS) may contribute to the improvement of patient reported outcome measures (PROMs) of fatigue in patients with primary Sjögren’s Syndrome (1). 

Objectives: This follow-up study uses the gammaCore device (electroCore) to assess the effect of nVNS on PROMs of fatigue and immune responses in chronic fatigue syndrome (CFS), FM and rheumatoid arthritis (RA). 

Methods: The study included thirteen CFS, fourteen FM and fifteen RA patients who used the gammaCore nVNS device twice daily over a 26-day period. Pre- and post- nVNS bloods were drawn at baseline and final visits. Whole blood samples were stimulated with 2 ng/mL lipopolysaccharide (LPS) and the IL-6 and TNF-α cytokine concentrations were quantified at 24 hours. In addition, the epidermal growth factor (EGF), IFN-γ, IL-6, IP-10, MIP-1α, and TNF-α levels were measured in ‘pre-nVNS’ serum and flow cytometric profiles of whole blood immune cells were analysed.

The patient reported outcome measures (PROMs) recorded at each visit were the Visual Analogue Scale (VAS) (0-100 cm) of abnormal fatigue, Hospital Anxiety and Depression (HAD) Scale, Orthostatic Grading Scale, Epworth Sleepiness Scale (daytime sleepiness), and Profile of fatigue (PRO-F) for Physical and Mental fatigue. Paired t-tests were performed to assess for changes in PROMs, cytokine levels, and cell subset distribution and associations of cytokine response with PROMs were investigated by correlation analyses. 

Results: Eleven CFS, twelve FM and fourteen RA patients completed the study. There was a significant reduction in daytime sleepiness in CFS (p =0.0321) and FM (p =0.0294) patients between the final and baseline visits and a significant reduction in HAD depression (p =0.0413) in FM (Fig.1).

Improvement in VAS for abnormal fatigue, HAD-Anxiety, HAD-Depression, PRO-F Physical and Mental fatigue was observed in all three groups over the study period with a reduction in VAS fatigue in 64% of CFS, 67% of FM and 62% of RA patients. There were no significant changes in the immune cell subsets or in cytokine response.

Finally, higher baseline pre-nVNS supernatant IL-6 levels were predictive of an improvement in VAS fatigue (p =0.0006), Daytime Sleepiness (p =0.0466) and PRO-F Physical fatigue (p =0.0196) in RA, while higher baseline TNF-α levels were predictive of an improvement in VAS fatigue (p =0.0003), Daytime Sleepiness (p =0.0380), Orthostatic (p =0.0281) and PRO-F Physical fatigue (p =0.0007) in FM. 

Conclusion: Our findings suggest that nVNS may contribute to the improvement of PROMs of fatigue in CFS, FM and RA. NVNS led to significant reductions in daytime sleepiness in CFS and FM, and depression in FM. Further studies and a larger sample size are needed to investigate the potential effects of nVNS on diseases characterised by persistent fatigue. 

Long-COVID Research References  

  1. Caspases and therapeutic potential of caspase inhibitors in moderate-severe SARS CoV2 infection and long COVID 
  2. Neurological consequences of neurovascular unit and brain vasculature damages: potential risks for pregnancy infections and COVID-19-babies 
  3. Return-to-work, disabilities and occupational health in the age of COVID-19 
  4. Navigating migraine care through the COVID-19 pandemic: an update 
  5. Incomplete Systemic Recovery and Metabolic Phenoreversion in Post-Acute-Phase Non hospitalized COVID-19 Patients: Implications for Assessment of Post-Acute COVID-19 Syndrome 
  6. Long COVID and the brain network of Proust's madeleine: targeting the olfactory pathway 
  7. Sequelae, persistent symptomatology and outcomes after COVID-19 hospitalization: the ANCOHVID multicentre 6-month follow-up study 
  8. Day by day symptoms following positive and negative PCR tests for SARS-CoV-2 in non-hospitalised health-care workers: a 90-day follow-up study 
  9. Long-COVID Headache 
  10. Unpacking post-covid symptoms 
  11. Longitudinal Neurocognitive and Pulmonological Profile of Long-Covid: the COVIMMUNE-Clin Study Protocol 
  12. Interleukin-6 as potential mediator of long-term neuropsychiatric symptoms of COVID-19 
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