ME Association regular research roundup

ME/CFS and Long Covid Research: 09 – 15 May 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

It’s been a busy week for research. There have been ten new ME/CFS studies and twenty-six new Long Covid studies this week.

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

Paper one (1) looks at distinguishing between controls and ME/CFS by looking at the biomolecules, in particular proteins, cytokines and extracellular vesicles. This study used 49 ME/CFS patients and 49 healthy controls.

This research used data which has been previously presented on this cohort on plasma cytokines (Nagy-Szakal et al., 2017) and plasma proteomics (Milivojevic et al., 2020), but sample were freshly prepared and they characterised the extracellular vesicles (EVs) present. Extracellular vesicles are nanosized, membrane-bound particles which are naturally released from almost all types of cells. They can transport other molecules, such as DNA, RNA and proteins between cells as part of intracellular communication, particularly in immune system response. The study then employed advanced statistical methods to compare the data alongside clinical measurements of health.

In summary, results found:

  • ME/CFS patients exhibited greater size and concentration of EVs in plasma.
  • Cytokine content in EVs revealed IL2 was significantly higher in ME/CFS (IL2 is an interleukin, which is a cytokine and part of the signalling molecules in the immune system).
  • Numerous correlations among EV cytokines, plasma cytokines, and plasma proteins using mass spectrometry proteomics were found (analytical tool for separating and identifying molecules).
  • Significant correlations between clinical data and protein levels suggest roles of particular proteins and pathways in the disease. For example, higher levels of specific pro-inflammatory cytokines (known as CSF2) and Tumor Necrosis Factor (TNFα) which were correlated with greater physical and fatigue symptoms in ME/CFS.
  • Higher serine protease SERPINA5, which is involved in haemostasis, was correlated with higher SF-36 general health scores in ME/CFS (self-reported measure of health questionnaire).
  • Machine learning classifiers were able to identify a list of 20 proteins which could discriminate between ME/CFS and controls, this could be further reduced to 7 which provided separation of the two groups.
  • Identification of ME/CFS or controls could also be done with a 86.1% accuracy (depending on the method used).
  • Results add to the growing evidence that there are significant differences in the biomolecules present in the blood of those with ME/CFS, and that the cytokine/chemokine signalling networks are altered.

There is a lot of interesting data in this paper, with a number of interesting new findings, however, it is particularly lengthy to read. It is worth a look at Figure 9 as it gives a graphical summary of the key finding from this study.

There are a few slight problems in the ways the study is presented, it’s not completely clear what case definition was used for ME/CFS, as there is conflicting information in the methods and results section as to whether just the Fukuda definition was used or this was reinforced with the Canadian Consensus as well. The Fukuda criteria is heavily criticised in its use to diagnosis ME/CFS, especially when used in research. For example, problems with the Fukuda criteria include: post-exertional malaise (PEM) is not compulsory which leads to misdiagnosis, and it is not easy to use on a clinical level (a review on the contrasting case definitions has been written by Brown et al., 2013). 

We have seen previous research which has used statistical methods to help differentiate between those with severe ME/CFS and healthy controls. This research found extracellular vesicles and microRNA to be particularly important for differentiating between groups (summary of the previous research is available here, González-Cebrián et al., 2022) (but oddly not cited in this recent study). Findings from this latest study are reassuring that we are moving towards finding a biomarker, with a not severely ill cohort to allow separation of groups. However, larger studies and verification of results is needed.

ME/CFS Research References and Abstracts 

1. Proteomics and cytokine analyses distinguish myalgic encephalomyelitis/chronic fatigue syndrome cases from controls

Giloteaux, L., Li, J., Hornig, M. et al. 

J Transl Med 21, 322 (2023).


Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex, heterogenous disease characterized by unexplained persistent fatigue and other features including cognitive impairment, myalgias, post-exertional malaise, and immune system dysfunction. Cytokines are present in plasma and encapsulated in extracellular vesicles (EVs), but there have been only a few reports of EV characteristics and cargo in ME/CFS. Several small studies have previously described plasma proteins or protein pathways that are associated with ME/CFS.

Methods: We prepared extracellular vesicles (EVs) from frozen plasma samples from a cohort of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) cases and controls with prior published plasma cytokine and plasma proteomics data. The cytokine content of the plasma-derived extracellular vesicles was determined by a multiplex assay and differences between patients and controls were assessed. We then performed multi-omic statistical analyses that considered not only this new data, but extensive clinical data describing the health of the subjects.

Results: ME/CFS cases exhibited greater size and concentration of EVs in plasma. Assays of cytokine content in EVs revealed IL2 was significantly higher in cases. We observed numerous correlations among EV cytokines, among plasma cytokines, and among plasma proteins from mass spectrometry proteomics. Significant correlations between clinical data and protein levels suggest roles of particular proteins and pathways in the disease. For example, higher levels of the pro-inflammatory cytokines Granulocyte-Monocyte Colony-Stimulating Factor (CSF2) and Tumor Necrosis Factor (TNFα) were correlated with greater physical and fatigue symptoms in ME/CFS cases. Higher serine protease SERPINA5, which is involved in hemostasis, was correlated with higher SF-36 general health scores in ME/CFS. Machine learning classifiers were able to identify a list of 20 proteins that could discriminate between cases and controls, with XGBoost providing the best classification with 86.1% accuracy and a cross-validated AUROC value of 0.947. Random Forest distinguished cases from controls with 79.1% accuracy and an AUROC value of 0.891 using only 7 proteins.

Conclusions: These findings add to the substantial number of objective differences in biomolecules that have been identified in individuals with ME/CFS. The observed correlations of proteins important in immune responses and hemostasis with clinical data further implicates a disturbance of these functions in ME/CFS.

2. Can we Reduce the Symptoms of Chronic Fatigue Syndrome by Regulating Micronutrients? A Review

Akduman, GUl; Kurtbeyoglu, Emine; Gunes, Fatma E.

Current Nutrition & Food Science, Volume 19, Number 5, 2023, pp. 509-518(10).


Introduction: Deficiencies of some micronutrients have been observed in chronic fatigue syndrome patients, but the underlying cause has not been fully understood. The aim of this study was to investigate whether there is a relationship between CFS and micronutrients.

Methods: Related articles searched the combinations of the following terms which were used for the search in the Web of Science database: “Chronic Fatigue Syndrome” OR “Chronic Fatigue- Fibromyalgia Syndrome” OR “Postviral Fatigue Syndrome” AND “vitamins” OR “minerals” OR “micronutrients”. Articles that met the inclusion criteria were included.

Results: The initial search resulted in 225 studies, with 11 studies fully meeting the inclusion criteria. In these studies, it has been shown that micronutrients may play a role in the etiology of CFS, and that supplemented micronutrients can positively affect the symptoms of CFS.

Conclusion: Although there seems to be a close relationship between CFS-related syndromes and nutritional status, the literature on this subject remains limited. The results of the studies were not compatible with each other due to differences in the studies. Therefore, new studies are needed to fully explain the relationship between CFS and micronutrients.

3. Whole-body cryotherapy as a treatment for chronic medical conditions?

Hanna Tabisz, Aleksandra Modlinska, Sławomir Kujawski, Joanna Słomko, Pawel Zalewski. 

British Medical Bulletin, 2023; ldad007.


Introduction: Whole-body cryotherapy (WBC) is a controlled exposure of the whole body to cold to gain health benefits. In recent years, data on potential applications of WBC in multiple clinical settings have emerged.

Sources of data: PubMed, EBSCO and Clinical Key search using keywords including terms ‘whole body’, ‘cryotherapy’ and ‘cryostimulation’.

Areas of agreement: WBC could be applied as adjuvant therapy in multiple conditions involving chronic inflammation because of its potent anti-inflammatory effects. Those might include systemic inflammation as in rheumatoid arthritis. In addition, WBC could serve as adjuvant therapy for chronic inflammation in some patients with obesity.

Areas of controversy: WBC probably might be applied as an adjuvant treatment in patients with chronic brain disorders including mild cognitive impairment and general anxiety disorder and in patients with depressive episodes and neuroinflammation reduction as in multiple sclerosis. WBC effects in metabolic disorder treatment are yet to be determined. WBC presumably exerts pleiotropic effects and therefore might serve as adjuvant therapy in multi-systemic disorders, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Growing points: The quality of studies on the effects of WBC in the clinical setting is in general low; hence, randomized controlled trials with adequate sample size and longer follow-up periods are needed.

Areas are timely for developing research: Further studies should examine the mechanism underlying the clinical efficacy of WBC. Multiple conditions might involve chronic inflammation, which in turn could be a potential target of WBC. Further research on the application of WBC in neurodegenerative disorders, neuropsychiatric disorders and ME/CFS should be conducted.

4. Astragalus polysaccharide ameliorated complex factor-induced chronic fatigue syndrome by modulating the gut microbiota and metabolites in mice

Xintong Wei, Jiayun Xin, Wei Chen, Jie Wang, Yanhui Lv, Yanping Wei, Zhanhong Li, Qianqian Ding, Yunheng Shen, Xike Xu, Xiuyun Zhang, Weidong Zhang, Xianpeng Zu.

Biomedicine & Pharmacotherapy, Volume 163, 2023, 114862.


  • Astragalus polysaccharide (APS) improve the learning and memory abilities and reduce despair in mcie with chronic fatigue syndrome (CFS).
  • APS ameliorates intestinal barrier damage and inflammation in CFS mice.
  • APS modulates the gut microbiota and increases levels of short chain fatty acids (SCFA) in CFS mice.
  • APS ameliorates oxidative stress and inflammation in the brain of CFS mice, an effect possibly mediated by promoting SCFAs production in the gut.


Chronic fatigue syndrome (CFS) is a debilitating disease with no symptomatic treatment. Astragalus polysaccharide (APS), a component derived from the traditional Chinese medicine A. membranaceus, has significant anti-fatigue activity. However, the mechanisms underlying the potential beneficial effects of APS on CFS remain poorly understood.

A CFS model of 6-week-old C57BL/6 male mice was established using the multiple-factor method. These mice underwent examinations for behavior, oxidative stress and inflammatory indicators in brain and intestinal tissues, and ileum histomorphology.

16 S rDNA sequencing analysis indicated that APS regulated the abundance of gut microbiota and increased production of short chain fatty acids (SCFAs) and anti-inflammatory bacteria.

In addition, APS reversed the abnormal expression of Nrf2, NF-κB, and their downstream factors in the brain-gut axis and alleviated the reduction in SCFAs in the cecal content caused by CFS.

Further, APS modulated the changes in serum metabolic pathways induced by CFS. Finally, it was verified that butyrate exerted antioxidant and anti-inflammatory effects in neuronal cells.

In conclusion, APS could increase the SCFAs content by regulating the gut microbiota, and SCFAs (especially butyrate) can further regulate the oxidative stress and inflammation in the brain, thus alleviating CFS.

This study explored the efficacy and mechanism of APS for CFS from the perspective of gut-brain axis and provides a reference to further explore the efficacy of APS and the role of SCFAs in the central nervous system.

5. Bamboo-based medicinal moxibustion for chronic fatigue syndrome: a randomized controlled trial

Xue KY, Quan F, Tang JX, Xiao CH, Lu CX, Cui J.

Zhongguo Zhen Jiu. 2023 May 12;43(5):493-8. [Article in Chinese.]


Objective: To observe the clinical efficacy of bamboo-based medicinal moxibustion for chronic fatigue syndrome (CFS), and to preliminarily explore its action mechanism.

Methods: Sixty-four patients with CFS were randomly divided into a moxibustion group (32 cases, 1 case dropped off, 1 case excluded) and an acupuncture group (32 cases, 2 cases dropped off). The patients in the moxibustion group were treated with bamboo-based medicinal moxibustion, while the patients in the acupuncture group were treated with routine acupuncture. Both groups were treated once a day, 6 days as a course of treatment with 1 day interval, for a total of 2 courses of treatment. Before treatment, 1 and 2 courses into treatment and in the follow-up of 14 days after treatment, the fatigue scale-14 (FS-14) and somatic and psychological health report (SPHERE) scores were observed in the two groups. Before and after treatment, the contents of CD+3, CD+4, CD+8 of peripheral blood T lymphocyte subsets were measured and CD+4/CD+8 ratio was calculated; the clinical efficacy of the two groups was compared. Results: Compared before treatment, the FS-14 and SPHERE scores in the two groups were decreased 1 and 2 courses into treatment and in the follow-up (P<0.01), and the FS-14 and SPHERE scores in the moxibustion group were lower than those in the acupuncture group (P<0.01, P<0.05). Compared before treatment, the contents of CD+3, CD+4 and CD+4/CD+8 ratio in the moxibustion group were increased after treatment (P<0.01).

There was no significant difference of CD+3, CD+4, CD+8 and CD+4/CD+8 ratio between before and after treatment in the acupuncture group (P>0.05). After treatment, the contents of CD+3 and CD+4 in the moxibustion group were higher than those in the acupuncture group (P<0.05). The total effective rate was 93.3% (28/30) in the moxibustion group, which was higher than 73.3% (22/30) in the acupuncture group (P<0.05).

Conclusion: Bamboo-based medicinal moxibustion could improve the physical and mental fatigue symptoms and psychological status in patients with CFS. Its effect may be related to regulating the contents of CD+3, CD+4 of peripheral blood T lymphocyte subsets and CD+4/CD+8 ratio.

6. Fatigue in Children and Adolescents: A Population-Based Longitudinal Study on Fatigue and Chronic Pain

Ariane Sommer, Susanne Grothus, Benedikt B Claus, Lorin Stahlschmidt, Julia Wager. 

Journal of Pediatric Psychology, 2023; jsad026.


Objective: There are limited data on the prevalence and stability of fatigue in pediatrics, particularly among youth with chronic pain. Little is known about longitudinal effects of fatigue on health outcomes such as sleep quality, psychological distress, Health-Related Quality of Life, and chronic pain.

Methods: A community-based sample of N = 1276 students (9–17 years; 52% female; 30.3% with chronic pain) from 3 schools was screened at 2 measurement points 3 months apart. Prevalence and stability of fatigue were examined. Longitudinal analyses regarding fatigue and health outcomes were run using repeated measures correlations. The impact of change in fatigue on pain progression was analyzed using multilevel linear models.

Results: In the total community sample, 4.4% reported severe fatigue symptoms. The prevalence of severe fatigue was significantly higher in students with chronic pain (11.4%) compared to those without (1.3%).

Fatigue symptoms persisted for several months, worsening of symptoms was more common and improvement less common in children with chronic pain.

Sleep, psychological distress, and Health-Related Quality of Life were significantly associated with fatigue across both measurement points (rs = |0.16–0.44|), with no significant differences in the strength of correlations between children with and without chronic pain (ps > .05). There was a significant interaction between change in fatigue and courses of pain intensity and functional impairment.

Conclusions: Fatigue is highly prevalent, particularly in youth with chronic pain. The negative association of fatigue with health outcomes, and its impact on the course of pain, require early identification and treatment of those affected to prevent negative long-term consequences.

7. Chronic Fatigue Syndrome: Risk Factors and Treatment Recommendations

Kılıçoğlu RB, Zerzevatcı C, Kayaaltı A, Erbaş O.

JEB Med Sci 2023;4(1): 71-75.


Chronic fatigue syndrome (CFS) is serious, a long-term disorder with a heterogeneous character that can be diagnosed based on clinical foundations or its symptoms. The cause or factors that lead to this condition, which lowers the patient's quality of life, cannot be fully determined, and there is no specific diagnosis. It has some triggering factors.

In addition to drug therapy, cognitive-behavioral therapy, sleep therapy, exercise therapy, and nutrition also contribute to the treatment of the condition. In this review, the causes of CFS were examined.

8. Positive Effects of Probiotic Therapy in Patients with Post-Infectious Fatigue

Obermoser K, Brigo N, Schroll A, Monfort-Lanzas P, Gostner JM, Engl S, Geisler S, Knoll M, Schennach H, Weiss G, Fuchs D, Bellmann-Weiler R, Kurz K.

Metabolites. 2023; 13(5):639. 


Post-infectious fatigue is a common complication that can lead to decreased physical efficiency, depression, and impaired quality of life. Dysbiosis of the gut microbiota has been proposed as a contributing factor, as the gut–brain axis plays an important role in regulating physical and mental health.

This pilot study aimed to investigate the severity of fatigue and depression, as well as the quality of life of 70 patients with post-infectious fatigue who received a multi-strain probiotic preparation or placebo in a double-blind, placebo-controlled trial.

Patients completed questionnaires to assess their fatigue (fatigue severity scale (FSS)), mood (Beck Depression Inventory II (BDI-II)), and quality of life (short form-36 (SF-36)) at baseline and after 3 and 6 months of treatment. Routine laboratory parameters were also assessed, including immune-mediated changes in tryptophan and phenylalanine metabolism.

The intervention was effective in improving fatigue, mood, and quality of life in both the probiotic and placebo groups, with greater improvements seen in the probiotic group. FSS and BDI-II scores declined significantly under treatment with both probiotics and placebo, but patients who received probiotics had significantly lower FSS (p < 0.001) and BDI-II (p < 0.001) scores after 6 months.

Quality of life scores improved significantly in patients who received probiotics (p < 0.001), while patients taking a placebo only saw improvements in the “Physical limitation” and “Energy/Fatigue” subcategories. After 6 months neopterin was higher in patients receiving placebo, while no longitudinal changes in interferon-gamma mediated biochemical pathways were observed.

These findings suggest that probiotics may be a promising intervention for improving the health of patients with post-infectious fatigue, potentially through modulating the gut–brain axis.

9. Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study

Gottschalk CG, Whelan R, Peterson D, Roy A.

International Journal of Molecular Sciences. 2023; 24(10):8713.


Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is a multisystem chronic illness characterized by severe muscle fatigue, pain, dizziness, and brain fog. Many patients with ME/CFS experience orthostatic intolerance (OI), which is characterized by frequent dizziness, light-headedness, and feeling faint while maintaining an upright posture. Despite intense investigation, the molecular mechanism of this debilitating condition is still unknown.

OI is often manifested by cardiovascular alterations, such as reduced cerebral blood flow, reduced blood pressure, and diminished heart rate. The bioavailability of tetrahydrobiopterin (BH4), an essential cofactor of endothelial nitric oxide synthase (eNOS) enzyme, is tightly coupled with cardiovascular health and circulation.

To explore the role of BH4 in ME/CFS, serum samples of CFS patients (n = 32), CFS patients with OI only (n = 10; CFS + OI), and CFS patients with both OI and small fiber polyneuropathy (n = 12; CFS + OI + SFN) were subjected to BH4 ELISA.

Interestingly, our results revealed that the BH4 expression is significantly high in CFS, CFS + OI, and CFS + OI + SFN patients compared to age-/gender-matched controls.

Finally, a ROS production assay in cultured microglial cells followed by Pearson correlation statistics indicated that the elevated BH4 in serum samples of CFS + OI patients might be associated with the oxidative stress response. These findings suggest that the regulation of BH4 metabolism could be a promising target for understanding the molecular mechanism of CFS and CFS with OI.

10. Effect of transcutaneous electrical acupoint stimulation on learning and memory ability of chronic fatigue syndrome rats and its mechanisms

Zhong XL, Tong BY, Yang YH, Zeng HL, Lin C, Jing Y, He LL, You SJ.

Zhen Ci Yan Jiu. 2023 Apr 25;48(4):317-24. [Article in Chinese.]


Objective: To observe the effect of transcutaneous electrical acupoint stimulation (TEAS) on the histomorphological manifestations of hippocampal CA1 region and the expression of extracellular regulatory protein kinase (ERK), cyclic adenosine response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in chronic fatigue syndrome (CFS) rats, so as to explore the mechanisms of TEAS in improving the learning and memory abilities of CFS rats.

Methods: Forty male Wistar rats were randomly divided into normal group (10 rats) and modeling group (30 rats); then after modeling, they were selected and randomly divided into model group (10 rats) and TEAS group (10 rats). CFS rats model was prepared by sleep deprivation combined with weight-bearing swimming. Rats in the TEAS group were stimulated with Han's acupoint nerve stimulator at bilateral “Zusanli” (ST36) and “Shenshu” (BL23) (2 Hz/15 Hz, 1-2 mA), 20 min each time, once a day for 4 weeks with 1 d rest every 6 d.

The score of general conditions of rats was evaluated. The learning and memory ability was tested with Morris water maze. The morphology and ultrastructure of hippocampal CA1 region were observed by HE staining and transmission electron microscopy. The expression levels of ERK, CREB and BDNF mRNAs and proteins in hippocampus were detected by real time quantitative PCR and Western blot, respectively.

Results: Compared with the normal group, the score of general condition was increased (P<0.01); the escape latency was prolonged (P<0.05, P<0.01) and the times of crossing the original platform was decreased (P<0.05); the expression levels of ERK, CREB and BDNF mRNAs and proteins in hippocampus were decreased (P<0.05, P<0.01) in the model group. Compared with the model group, the scores of general condition on the 42nd and 49th day were decreased (P<0.05, P<0.01); the escape latency was shortened (P<0.01, P<0.05)and the times of crossing the original platform were increased (P<0.05); the expression levels of ERK, CREB and BDNF mRNAs and proteins in hippocampus were increased (P<0.01, P<0.05) in the TEAS group.

The morphology of neurons in hippocampal CA1 region was normal in the normal group. In the model group, the number of neurons in hippocampal CA1 region decreased, the arrangement of nerve cells was scattered, the number of apoptotic cells increased, some nuclear structures disappeared, nuclear heterochromatin increased, the cell membrane wrinkled, the chromatin appeared empty bright area, and the crista was incomplete.

Compared with the model group, the nerve cells morphology in hippocampal CA1 region was more regular, the number of apoptotic cells decreased, the chromatin and the cytoplasm were uniformly distributed, and the crista was relatively intact in the TEAS group.

Conclusion: TEAS can improve the learning and memory ability of CFS rats, the mechanisms may be related to improving the neural structure of hippocampal CA1 region and up-regulating the expression levels of ERK/CREB/BDNF.

Long-COVID Research References

Dr Katrina Pears,
Research Correspondent.
The ME Association.

Dr Katrina Pears - MEA Research Correspondent
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