Images of research to illustrate the weekly research roundup

ME/CFS and Long Covid Research: 27 November – 04 December 2023 

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


The ME Association maintains a comprehensive index of published research on ME/CFS and Long Covid that is free to use and updated weekly.

Audio commentary by Dr Katrina Pears

ME/CFS Research Published 27 November – 4 December 2023 

There have been five new ME/CFS studies and twenty-one new Long Covid studies this week. 

We have highlighted one of the ME/CFS studies in more detail below: 

Paper four (4) this week is a preprint (meaning the science has not been peer-reviewed and verified) which looks into the relationship between immunological characteristics and intestinal barrier function in ME/CFS patients. 

This study recruited 39 ME/CFS patients and 19 healthy controls. The ME/CFS patients were then immunologically stratified during diagnostic evaluations based on their immune competence, this divided ME/CFS patients into two groups, without immunodeficiencies (-ID) (n=19) and with immunodeficiencies (+ID) (n=20). After documentation of detailed medical records, serum and plasma samples were collected for assessment of inflammatory immune mediators and biomarkers for intestinal barrier integrity by ELISA (enzyme-linked immunosorbent assays- a type of laboratory technique). 

Graphic taken from the study by Rohrhofer et al., 2023

Some of the notable differences in the study were: 

Pro-inflammatory immune mediators: 

  • Decrease in plasma C4A concentrations for +ID ME/CFS patients compared to -ID ME/CFS and healthy controls. 
  • Reduction in serum IL-1 beta levels in -ID ME/CFS patients compared to healthy controls. 
  • Increase in serum IL-33 in -ID ME/CFS compared to healthy controls but slightly increased when compared to +ID ME/CFS patients. 
  • Serum IL-6 levels were significantly elevated in -ID ME/CFS patients compared to healthy controls. 
  • TNF‐alpha, IL‐8 and FGF21 serum did not differ between groups. 

Immune markers related to enhanced mast-cell activity and eosinophil activation:  

  • ECP (eosinophil cationic protein) was not different between groups. 
  • EDN (eosin‐derived neurotoxin) was more elevated in +ID ME/CFS and -ID ME/CFS patients but this was not significantly different to controls.  

Biomarkers Associated to Mucosal and Intestinal Barrier Integrity: 

  • Serum LBP (lipopolysaccharide‐binding protein) were significantly increased in -ID ME/CFS compared to healthy controls. 
  • I‐FABP levels were slightly reduced in -ID ME/CFS patients compared to healthy controls. 
  • Soluble CD14 serum level, (needed as a co‐factor together with LBP to mediate innate immunity against LPS to the immune system), did not differ between the groups. 
  • Endotoxin‐core IgG‐antibodies were highest in +ID ME/CFS patients, while -ID ME/CFS and healthy controls had similar levels. 

The authors summarise the fundamental findings as: 

  • For immunodeficient patients they had reduced complement protein C4a levels which suggests a sub-group specific innate immune dysregulation. 
  • For patients without immunodeficiency they exhibited a mucosal barrier leakage, as indicated by elevated levels of Lipopolysaccharide-binding protein (LBP). 
  • The study showed that stratifying ME/CFS patients based on immune competence enabled the distinction of two subgroups with different pathophysiological patterns.  

A huge focus of this paper is the importance of patient immunological stratification but this is also where we question the methodology of the paper. There is very little detail given of how immunodeficiency was defined in this paper. The only information given states that immunodeficiency was classed on a set of immunological parameters, where: Mannose-binding lectin (MBL) 55%, Ig/Ig-subclass 35%, Leukocyte composition 25% and complement factors 10%. All these parameters are associated with higher risks of infection, however, we do not know how levels relate to these parameters, i.e. if higher or lower than the value given gives +ID or -ID. Furthermore, no source is cited of where these parameters come from or are used, and we have not come across a study where this has been used before. 

A few other things to note about this study: 

  • ME/CFS was diagnosed based on the Institute of Medicine (IOM) criteria. 
  • All patients were mild to moderately affected, apart from one severely affected patent in the -ID group. 
  • As a large part of the discussion in the paper focuses on the gut and mucosal barrier leakage it is a shame that the researchers did not look into gut microbiota or relate symptoms to levels. 
  • Some of the findings that are noted as being statistically significant between the three groups, look disappointing in the figures displayed so questions the true meaning of the results. 

This is definitely an interesting study with a range of analyses being used which investigates the mucosal intestinal barrier in ME/CFS and immunodeficiencies, showing distinct pathophysiological mechanisms between the two ME/CFS groups. These findings could have implications for diagnosing ME/CFS and targeted treatment, although I would like a stronger background presented on the immunological stratification used. 

You may also be interested in reading this week in the Long Covid reference section: 

  • Paper one (1) which suggests biomakers which could be used to diagnose Long Covid, you can find more coverage on this paper here
  • Paper four (4) which is a longitudinal study showing that severity and symptoms change over time, with further coverage here
  • Paper six (6) which is on the prevalence of Long Covid in Scotland

ME/CFS Research References  

1. DNA Methylation Changes in Blood Cells of Fibromyalgia and Chronic Fatigue Syndrome Patients 

Patrycja Kamila Przybylowicz, Katarzyna Ewa Sokolowska, Hubert Rola , Tomasz Kazimierz Wojdacz. 

Journal of Pain Research 16: 4025-4036. 


Purpose: Fibromyalgia (FM) and Chronic Fatigue Syndrome (CFS) affect 0.4% and 1% of society, respectively, and the prevalence of these pain syndromes is increasing. To date, no strong association between these syndromes and the genetic background of affected individuals has been shown. Therefore, it is plausible that epigenetic changes might play a role in the development of these syndromes.  

Patients and Methods: Three previous studies have attempted to elaborate the involvement of genome-wide methylation changes in blood cells in the development of fibromyalgia and chronic fatigue syndrome. These studies included 22 patients with fibromyalgia and 127 patients with CFS, and the results of the studies were largely discrepant. Contradicting results of those studies may be attributed to differences in the omics data analysis approaches used in each study. We reanalyzed the data collected in these studies using an updated and coherent data-analysis framework.  

Results: Overall, the methylation changes that we observed overlapped with previous results only to some extent. However, the gene set enrichment analyses based on genes annotated to methylation changes identified in each of the analyzed datasets were surprisingly coherent and uniformly associated with the physiological processes that, when affected, may result in symptoms characteristic of fibromyalgia and chronic fatigue syndrome.  

Conclusion: Methylomes of the blood cells of patients with FM and CFS in three independent studies have shown methylation changes that appear to be implicated in the pathogenesis of these syndromes. 

2. Bridging Uncertainties: Exploring the Lived Experiences of Pediatric Long-COVID-19 Through ME/CFS Caregiver Narratives 

Rita Komalasari 
Clinical Practice and Post-Infection Care for COVID-19 Patients 


The study aims to bridge knowledge gaps by exploring the challenges parents face caring for children with ME/CFS, using their narratives to understand long-term. This approach seeks to uncover parallels, enhancing our understanding of pediatric long-COVID-19 and informing effective caregiving strategies.  

In the authors' exploration, a comprehensive literature study is the guiding light. A rigorous analysis of existing research illuminates the similarities between long-term COVID-19 and ME/CFS experiences in children.  

The analysis revealed striking similarities between the caregiving experiences in ME/CFS and long-term COVID-19 cases. Parents' narratives illuminated the relentless nature of these conditions, shedding light on the emotional toll they take. By recognising these parallels, healthcare providers and families can benefit from informed strategies, ultimately improving the quality of care provided to children affected by COVID-19.  

This research supports a more comprehensive view of pediatric long-term ICU illness, one that considers physical symptoms and psychological and social ones. 

3. An international survey of experiences and attitudes towards transcutaneous auricular vagus nerve stimulation for people with Myalgic Encephalomyelitis/chronic fatigue syndrome 

Karen Leslie, Nicola Clague-Baker, Mohammad Abdelfattah Atallah Madi, Dawn Wiley, Andrea Parker, Michelle Bull & Natalie Hilliard. 

Fatigue: Biomedicine, Health & Behavior. 


Background and objectives: Myalgic encephalomyelitis (ME) is a complex, multi-system neurological condition. Dysfunction of the autonomic nervous system is a primary feature in diagnostic criteria, and management may include attempts to stimulate the parasympathetic nervous system. Transcutaneous auricular vagus nerve stimulation is an intervention that has been researched in neurological disorders, e.g. epilepsy, depression. While little evidence exists for its use in ME, this survey aims to explore the experiences and attitudes of people with ME to this intervention. 

Methods: A 31-question online survey was devised and released on ME websites, Twitter and Facebook pages. People with ME read the information sheet and followed an online link to the survey. The survey was open for four weeks and all answers were anonymous. 

Results: 116 responses were received. 56% of respondents reported favourable effects. Benefits of transcutaneous auricular vagus nerve stimulation were identified in relation to post exertional malaise, pain, gut problems, urinary problems, mental health, and the ability to leave the house. 67.2% of respondents would recommend the intervention to other people with ME. However, 4.3% would not recommend it and 6% reported it made them worse. 8.6% received support in setting up the device from healthcare workers. 

Conclusion: The survey highlights that many people with ME experience significant benefits from using transcutaneous auricular vagus nerve stimulation; however due to potential negative effects there is the need for formal intervention studies to clearly identify safe parameters. 

4. Immunological Patient Stratification in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome 

Rohrhofer, J.; Hauser, L.; Lettenmaier, L.; Lutz, L.; Koidl, L.; Gentile, S.A.; Ret, D.; Stingl, M.; Untersmayr, E.  

Preprints 2023, 2023112007. 


Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex disease characterized by profound fatigue, post-exertional malaise (PEM), and neurocognitive dysfunction. Immune dysregulation and gastrointestinal symptoms are commonly observed in ME/CFS patients. Despite affecting approximately 0.89% of the general population, the underlying pathophysiological mechanisms remain poorly understood.  

This study aimed to elucidate the relationship between immunological characteristics and intestinal barrier function in ME/CFS patients.  

ME/CFS patients were stratified into two groups based on their immune competence. After documentation of detailed medical records, serum and plasma samples were collected for assessment of inflammatory immune mediators and biomarkers for intestinal barrier integrity by ELISA.  

We found reduced complement protein C4a levels in immunodeficient ME/CFS patients suggesting a sub-group specific innate immune dysregulation.  

ME/CFS patients without immunodeficiencies exhibit a mucosal barrier leakage, as indicated by elevated levels of Lipopolysaccharide-binding protein (LBP).  

Stratifying ME/CFS patients based on immune competence enabled the distinction of two subgroups with different pathophysiological patterns. 

The study highlights the importance of emphasizing precise patient stratification in ME/CFS, particularly in the context of defining suitable treatment strategies. Given the substantial health and socioeconomic burden associated with ME/CFS, urgent attention and research efforts are needed to define causative treatment approaches. 

5. Exploring the Joint Potential of Inflammation, Immunity, and Receptor-Based Biomarkers for Evaluating ME/CFS Progression 

Uldis Berkis, Simons Svirskis, Angelika Krumina, Sabine Gravelsina, Anda Vilmane, Diana Araja, Zaiga Nora-Krukle, Modra Murovska. 

Frontiers in Immunology. Volume 14- 2023. 

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic condition with no identified diagnostic biomarkers to date. Its prevalence is as high as 0.89% according to metastudies, with a quarter of patients bed-or home-bound, which presents a serious public health challenge. Investigations into the inflammation-immunity axis is encouraged by links to outbreaks and disease waves. Recently, research of our group revealed that antibodies to beta2adrenergic (anti-β2AdR) and muscarinic acetylcholine (anti-M4) receptors demonstrate sensitivity to the progression of ME/CFS.  

The purpose of this study is to investigate the joint potential of inflammatome -characterized by interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-2, IL-21, Il-23, IL-6, IL-17A, Activin-B, immunome (IgG1, IgG2, IgG3, IgG4, IgM, IgA) and receptorbased biomarkers (anti-M3, anti-M4, anti-β2AdR) determined for evaluating ME/CFS progression, and to identify an optimal selection for future validation in prospective clinical studies.  

Methods: A dataset was used originating from 188 persons, including 54 healthy controls, 30 patients classified as “mild” by severity, 73 as “moderate,” and 31 as “severe,” clinically assessed by Fukuda/CDC 1994 and International consensus criteria. Markers characterizing inflammatome, immunome, and receptor-based biomarkers were determined in blood plasma via ELISA and multiplex methods.  

Statistical analysis was done via correlation analysis, principal component, and linear discriminant analysis, and random forest classification; inter-group differences tested via nonparametric Kruskal-Wallis H test followed by the two-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli, and via Mann-Whitney U test.  

The association between inflammatome and immunome markers is broader and stronger (coupling) in severe group. Principal component factoring separate components affiliated with inflammatome, immunome, and receptor biomarkers. Random forest modeling demonstrates an outof-box accuracy for splitting healthy/with condition groups of over 90%, and of 45% for healthy/severity groups. Classifiers with the highest potential are anti-β2AdR, anti-M4, IgG4, IL-2, and IL-6.  

Discussion: Association between inflammatome and immunome markers is a candidate for controlled clinical study of ME/CFS progression markers that could be used for treatment individualization. Thus, coupling effects between inflammation and immunity have a potential for the identification of prognostic factors in the context of ME/CFS progression mechanism studies. 

Long-COVID Research References  

  1. Complement dysregulation is a predictive and therapeutically amenable feature of long COVID 
  1. The association of insomnia with long COVID: An international collaborative study (ICOSS-II) 
  1. The effectiveness of COVID-19 vaccine in the prevention of post-COVID conditions: a systematic literature review and meta-analysis of the latest research 
  1. Long Covid Clinical Severity Types Based on Symptoms and Functional Disability: A Longitudinal Evaluation 
  1. Remission of severe forms of long COVID following monoclonal antibody (MCA) infusions: A report of signal index cases and call for targeted research 
  1. True prevalence of long-COVID in a nationwide, population cohort study 
  1. Cortical thickness alterations and systemic inflammation define long-COVID patients with cognitive impairment 
  1. Drawing the Line Between Postacute Sequelae of COVID-19 and Functional Neurologic Disorders- A Daunting Clinical Overlap or Irrelevant Conundrum? 
  1. SGLT2 Inhibitors in Long COVID Syndrome: Is There a Potential Role? 
  1. Exploring the Influence of VDR Genetic Variants TaqI, ApaI, and FokI on COVID-19 Severity and Long-COVID-19 Symptoms 
  1. Long-term neurological dysfunction associated with COVID-19: Lessons from influenza and inflammatory diseases? 
  1. Molecular Mechanisms Involved in the Occurrence and Progression of Long COVID and Associated Analysis Techniques 
  1. Pandemic Preparedness and the Workforce: Employer Experiences with Long COVID 
  1. Incidence of long-term post-acute sequelae of SARS-CoV-2 infection related to pain and other symptoms: A systematic review and meta-analysis 
  1. All eyes on PCS: analysis of the retinal microvasculature in patients with post-COVID syndrome-study protocol of a 1 year prospective case-control study 
  1. Pediatric Post-Acute Sequelae of SARS-CoV-2 Infection 
  1. Sex differences in vascular endothelial function related to acute and long COVID-19 
  1. Analysis of the correlation between heart rate variability and palpitation symptoms in female patients with long COVID 
  1. Memory, Emotion, and Quality of Life in Patients with Long COVID-19 
  1. The long COVID haul 
  1. Comparison of post-acute sequelae following hospitalization for COVID-19 and influenza 

Dr Katrina Pears,
Research Correspondent.
The ME Association.

Dr Katrina Pears - MEA Research Correspondent



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