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).
RESEARCH INDEX
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 another incredibly busy week for research, with ten new ME/CFS studies and twenty new Long Covid studies. /
We have highlighted one of the ME/CFS studies in more detail below:
Paper ten (10) is on circulating microRNAs (miRNAs) expression in ME/CFS, these are short non-coding RNA sequences which are involved in the regulation of gene expression helping cells to control the type and amounts of proteins they make. MicroRNAs have been suggested as being involved in modulating the factors involved in the pathology of ME/CFS, in addition their presence in the blood may provide a biomarker to distinguish between controls and those with ME/CFS.
This study looked at eight miRNAs which had been identified in previous research in 40 patients with ME/CFS and 20 healthy controls. They looked at correlations between miRNAs’ expression and disease severity, as well as plasma pro-inflammatory cytokines, and HHV-6 infection/reactivation. Table 1 in the paper lists each of these miRNAs and their association and potential role in ME/CFS, which is worth a look at to further understand the specific miRNAs.
The results showed:
- Six out of the eight miRNAs studies were differently expressed in ME/CFS compared to controls.
- Of these, five were significantly upregulated (miR-127-3p, miR-142-5p, miR-143-3p, miR-150-5p, and miR-448)
- A further one of the miRNA’s (miR-140-5p) was down-regulated.
- MiRNA levels directly correlated with disease severity.
- No significant correlations were observed with the plasma levels of seven pro-inflammatory cytokines or with the presence/load of HHV-6A/6B genome.
This research has its strength in verifying results from previous research, where the results reinforce previous findings rather than adding to the vast amount of research which is not followed up. This study also helps to reinforce results from previous weaker research, for example, one of the studies which identified significant miRNAs in ME/CFS was by Brenu et al., 2014, which only used six patients with ME/CFS and six healthy controls.
This is also one of the few studies which use and detail the severity of the ME/CFS participants, here there were 5 severe, 22 moderate and 13 mild. The researchers compare the results for the ME/CFS entire sample as well as breaking it down into severities, which is done very clearly and shows different trends.
There are not many limitations to this study. However, unfortunately, they used the Fukuda criteria in this study which is heavily criticised in its use to diagnose 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).
Like most ME/CFS research, this study was limited by its size, therefore, further verification of results is needed. In particular the researchers could not support the role of herpesvirus infections (particularly HHV-6A/B) as a possible trigger for ME/CFS. Sample size was one of the factors meaning no significant difference being found between ME/CFS patients and controls for positive HHV-6A/6B infection and viral load. Additionally, this study also did not have age and sex matched controls, with a difference in the mean age between the two groups (ME/CFS 49.3 years verus controls 33.4 years).
In conclusion, we need more studies like this which set out to verify results and also help to overcome the limitations found in previous research, such as poorly designed protocols. Hopefully, this will lead us a step closer to finding a biomarker and validating the use of miRNAs for clinical diagnosis. However, for this we also need to know how miRNAs change over time with longitudinal ME/CFS studies.
In the Long Covid Reference section, paper two (2) on treating Long Covid may be of interest, Dr Charles Shepherd has provided a short comment on this study.
ME/CFS Research Published 20 – 26 June 202
Gang He, Yu Cao, Wangzi Xu and Houzhao Wang.
Front. Microbiol. Volume 14 – 2023.
Abstract
Background: Evidence from previous studies have implicated an important association between gut microbiota (GM) and Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS), but whether there is a definite causal relationship between GM and ME/CFS has not been elucidated.
Method: This study obtained instrumental variables of 211 GM taxa from the Genome Wide Association Study (GWAS), and mendelian randomization (MR) study was carried out to assess the effect of gut microbiota on ME/CFS risk from UK Biobank GWAS (2076 ME/CFS cases and 460857 controls).
Inverse variance weighted (IVW) was the primary method to analyze causality in this study, and a series of sensitivity analyses was performed to validate the robustness of the results.
The inverse variance weighted (IVW) method indicated that genus Paraprevotella (OR:1.001, 95%CI:1.000-1.003, p-value<0.05) and Ruminococca-ceae_UCG_014(OR 1.003, 95% CI 1.000 to 1.005, p-value < 0.05) were positively associated with ME/CFS risk.
Results from the weighted median method supported genus Paraprevotella (OR 1.003, 95% CI 1.000 to 1.005, p-value < 0.05) as a risk factor for ME/CFS.
Conclusions: This study reveals a causal relationship between genus.paraprevotella, genus.Ruminococcaceae_UCG_014 and ME/CFS, and our findings provide novel insights for further elucidating the developmental mechanisms mediated by the gut microbiota of ME/CFS.
2. A Thesis on Immune Differences in Chronic Fatigue Syndrome, Fibromyalgia and Healthy Controls
Groven, N.
PhD Thesis [Norwegian University of Science and Technology]
Abstract
Background: Chronic Fatigue Syndrome (CFS) and Fibromyalgia (FM) are debilitating disorders that significantly affect the daily lives of those suffering from them, as well as their loved ones. Both conditions have overlapping clinical features that resemble inflammatory disorders, and overlapping symptoms, such as depression, suggest central nervous system (CNS) involvement. The role of the immune system’s soluble messengers in the pathogenesis of CFS and FM has been under investigation, but so far the results are inconclusive. In addition, there is growing evidence that the kynurenine pathway is involved in the pathology of diseases related to the CNS, yet the role of each metabolite is not clear. The relationship between kynurenine metabolism and CFS and FM has not been extensively explored. Few studies have simultaneously examined the immunological status in both CFS and FM, making this thesis the first to comprehensively evaluate the potential distinct immunological differences between the two disorders.
Objective: The objective of this study was to compare the CFS and FM with healthy controls, regarding the levels of several soluble blood markers related to the immune system. The markers chosen were:
- The inflammatory marker high-sensitive CRP (hsCRP)
- The following cytokines and chemokines: Interferon (IFN)-γ, Interleukin (IL)-1β, IL1ra, IL-4, IL-6, IL-8, IL-10, IL-17, Interferon gamma-induced protein (IP)-10, Monocyte Chemoattractant Protein (MCP)-1, Transforming Growth Factor (TGF)-β1, TGF-β2, TGF-β3 and Tumour Necrosis Factor (TNF)-α
- The metabolites and their ratios of the kynurenine pathway: Tryptophan (Try), kynurenine (Kyn), kynurenic acid (KA), 3-hydroxykykynurenine (HK), anthranilic acid (AA), xanthurenic acid (XA), 3-hydroxyanthranilic acid (HAA), quinolinic acid (QA) and picolinic acid (Pic).
Method: The population consisted of three groups: CFS patients (n = 49), FM patients (n = 58), and healthy controls (n = 54). All participants were females aged 18–60. Patients were recruited from a specialised university hospital clinic and controls were recruited by advertisement among the staff and students at the hospital and university.
Plasma levels of hsCRP were analysed at the hospital. The cytokines and chemokines IFN-γ, IL-1β, IL-1ra, xii IL-4, IL-6, IL-8, IL-10, IL-17, IP-10, MCP-1, TGF-β1, TGF-β2, TGF-β3, and TNF-α were analysed by multiplex. Kynurenine metabolites were analysed by LC-MS/MS.
Linear regression models of log-transformed data for hsCRP and the kynurenine metabolites were conducted for comparison of the three groups CFS, FM and controls. The Kruskal-Wallis test was used to analyse differences of cytokines between the three groups. Main findings were controlled for age, body mass index (BMI), and symptoms of anxiety and depression.
Results: hsCRP levels were significantly higher for both the CFS and FM groups compared to healthy controls when adjusting for age and BMI (p = .006). There was no difference between the two patient groups. Level of hsCRP was affected by BMI (p < .001) but not age.
MCP-1 was significantly increased in both patient groups compared to healthy controls (p < .001). IL-1β, Il-4, IL-6, TNF-α, TGF-β1, TGF-β2, TGF-β3 (all p < .001), IL-10 (p = .003) and IL17 (p = .002) all were significantly lower in the patient groups compared to healthy controls. IFN-γ was significantly lower in the FM group (p < .001). For IL-8, IP-10 and IL1ra there were no significant difference.
QA differed between CFS and FM patients (p = .036) and was related to higher levels of BMI (p = .002). The KA/QA ratio was lower for CFS patients compared to healthy controls (p = .016). The KA/HK ratio was lower for FM patients compared to healthy controls, and this lower ratio was associated with increased symptoms of pain (p = .002). The kynurenine aminotransferase II (KAT II) enzymatic activity given by XA/HK was lower for FM patients compared to healthy controls (p = .013). In addition, BMI was negatively associated with enhanced KAT II enzymatic activity (p = .039).
Symptoms of anxiety and depression were not associated with any of the immune markers studied.
Conclusion: In our material hsCRP and MCP-1 are increased in patients both with CFS and with FM, while several other cytokines are either similar or significantly lower in patients than controls. Our study also indicates associations between kynurenine metabolism and CFS and FM. Kynurenine also is associated with single symptoms such as fatigue and pain. Forthcoming studies indicating interactions and causative effects, or restoration of the inflammatory status, may place cytokines and kynurenine metabolites as a target for treatment as well as prevention of these conditions in the future.
3. Symptoms and signs of dry eye in US veterans with Myalgic encephalomyelitis/chronic fatigue syndrome
Victor Sanchez; Colin Kim; Kimberly Cabrera; Elyana Vittoria Tessa Locatelli; Molly Johnson; Anat Galor.
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 3978.
Abstract
Purpose: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is clinically defined as persistent and unexplainable post-exertional fatigue and can present with a wide range of cognitive, immunological, endocrinological, and autonomic symptoms. A notable feature of ME/CFS is its comorbidity with pain in multiple compartments. In this study, we examine ocular manifestations associated with ME/CFS, with a focus on ocular surface pain complaints.
Methods: We recruited 124 United States veterans and profiled them for symptoms and signs of dry eye (DE). Individuals were grouped by the presence (n=42) and absence (n=82) of ME/CFS.
Results: The mean age of the population was 55.49 ± 4.61 years, 88.7% of participants identified as male, 58.1% as White, and 39.5% as Hispanic. Demographics, medical comorbidities, and medication use were similar between groups except for depression (57.1% vs. 29.6%, p=0.003), and history of traumatic brain injury (9.5% vs. 1.2%, p=0.03) which were more prevalent in the ME/CFS group. Individuals with ME/CFS reported higher ocular surface pain complaints, both through DE specific questionnaires (Ocular Surface Disease Index, OSDI; 5-Item DE Questionnaire, DEQ-5) and pain specific questionnaires (Neuropathic Pain Symptom Inventory, modified for the Eye, NPSI-E; Numerical rating scale, NRS) (Table 1). Ocular surface parameters were similar between groups, except for persistent pain after topical anesthesia which was more frequent in the ME/CFS group (Table 2).
Conclusions: Individuals who met criteria for ME/CFS had more severe ocular surface pain, but similar signs of DE, compared to controls. This suggests that nerve, and not tear, abnormalities contribute to ocular surface pain in ME/CFS.
Heather Wei, Zoe Adelsheim, Rita Fischer, Michael J. McCarthy.
Journal of Neuroimmunology, 578142 [In Press, Journal Pre-proof]
Abstract
Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling disorder characterized by disrupted daily patterns of activity, sleep, and physiology.
Past studies in ME/CFS patients have examined circadian rhythms, suggested that desynchronization between central and peripheral rhythms may be an important pathological feature, and identified associated changes in post-inflammatory cytokines such as transforming growth factor beta (TGFB). However, no previous studies have examined circadian rhythms in ME/CFS using cellular models or studied the role of cytokines on circadian rhythms.
In this study, we used serum samples previously collected from ME/CFS patients (n = 20) selected for the presence of insomnia symptoms and matched controls (n = 20) to determine the effects of serum factors and TGFB on circadian rhythms in NIH3T3 mouse immortalized fibroblasts stably transfected with the Per2-luc bioluminescent circadian reporter.
Compared to control serum, ME/CFS serum caused a significant loss of rhythm robustness (decreased goodness of fit) and nominally increased the rate of damping of cellular rhythms. Damping rate was associated with insomnia severity in ME/CFS patients using the Pittsburgh Sleep Quality Index (PSQI). Recombinant TGFB1 peptide applied to cells reduced rhythm amplitude, caused phase delay and decreased robustness of rhythms.
However, there was no difference in TGFB1 levels between ME/CFS and control serum indicating the effects of serum on cellular rhythms cannot be explained by levels of this cytokine. Future studies will be required to identify additional serum factors in ME/CFS patients that alter circadian rhythms in cells.
Mayte Serrat, Estíbaliz Royuela-Colomer, Sandra Alonso-Marsol, Sònia Ferrés, William Auer, Anna Muro, Ruben Nieto, Albert Feliu-Sole.
ResearchSquare [Preprint]
Abstract
Background/Objectives: The main objective of the present study is to assess the short-term effects of Forest Bathing (FB) conducted in a Mediterranean forest on individuals with fibromyalgia (FM) and/or Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) on perceived pain, fatigue, state anxiety, positive and negative affect, mood states, and state mindfulness.
Methods: A total of 44 participants with FM and/or CSF/ME agreed to participate in this study. The FB session consisted of a 3km silent walk, lasting three hours long and guided by a specialized psychologist and a mountain guide to guarantee the safety of the activity. Paired-sample t-tests were used to analyze the prepost changes in perceived pain, fatigue, state anxiety, positive and negative affect, mood states and mindfulness.
Results: All reported variables but self-reported pain showed statistically significant pre-post variations after the FB session. Particularly, large-to-very-large improvements in positive and negative affect, state anxiety, tension, depression, anger, and vigor were found. Small-to-moderate effect sizes for fatigue, friendliness and state mindfulness were also reported.
Conclusions: This study provides preliminary evidence of the short-term benefits of FB in individuals with FM and/or CFS/ME, especially on state anxiety and negative affect.
Prajjwal P, Kalluru PKR, Marsool MD, Inban P, Gadam S, Al-Ezzi SMS, Marsool AD, Al-Ibraheem AMT, Al-Tuaama AZH, Amir O, Arunachalam SP.
Ann Med Surg (Lond). 2023 May 26;85(6):2821-2832.
Abstract
Multiple sclerosis (MS) and myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) share the symptom of fatigue, and might even coexist together. Specifically focusing on genetics, pathophysiology, and neuroimaging data, the authors discuss an overview of the parallels, correlation, and differences in fatigue between MS and ME/CFS along with ME/CFS presence in MS.
Studies have revealed that the prefrontal cortex and basal ganglia regions, which are involved in fatigue regulation, have similar neuroimaging findings in the brains of people with both MS and ME/CFS. Additionally, in both conditions, genetic factors have been implicated, with particular genes known to enhance susceptibility to MS and CFS.
Management approaches for fatigue in MS and ME/CFS differ based on the underlying factors contributing to fatigue.
The authors also focus on the recent updates and the relationship between MS and sleep disorders, including restless legs syndrome, focusing on pathophysiology and therapeutic approaches. Latest therapeutic approaches like supervised physical activity and moderate-intensity exercises have shown better outcomes.
7. Research progress on central mechanism of acupuncture treatment for chronic fatigue syndrome
Li BB, Feng CW, Qu YY, Sun ZR, Chen T, Wang YL, Wang QY, Lu J, Shao YY, Yang TS.
World J Acupunct Moxibustion. [Epub ahead of print.]
Abstract
Chronic fatigue syndrome is a neurological disorder characterized by extreme fatigue that lasts for a long time and doesn't alleviate with rest. The number of the cases has been increasing during the era of COVID-19 pandemic.
Acupuncture may have some effect on chronic fatigue syndrome, but its mechanism remains unclear. This article was to summarize the specific manifestations of abnormal central mechanism in patients with chronic fatigue syndrome through laboratory tests and neuroimaging.
It was found from the laboratory evaluation that there were changes in the structure of the frontal cortex, thalamus and other brain tissues; factors, including IFN-α and IL-10 in cerebrospinal fluid were found abnormal; results of oxidative and nitrosative stress and changes in neurobiochemical substances, e.g. hypothalamus hormone levels and neurotransmitter concentrations, were observed.
With magnetic resonance imaging and positron emission tomography, it was shown that the partial brain of persons with chronic fatigue syndrome had morphological changes with diminished grey matter and white; changes in cerebral blood flow velocity caused by decreased perfusion and functional activity with abnormal connectivity in brain were detected.
In addition, there was significant decrease in glucose metabolism accompanied with neuroinflammatory response; metabolic disorders of serotonergic, cholinergic, glutamatergic and γ-aminobutyric acid energy neurotransmitters were also discovered.
The regulatory effect of acupuncture on the above central neurological abnormalities in chronic fatigue syndrome model animals was elaborated, and the direction for further research was analyzed in order to provide ideas for further research on the central mechanism of acupuncture treatment for chronic fatigue syndrome.
Du Preez S, Eaton-Fitch N, Smith PK, Marshall-Gradisnik S.
Biomolecules. 2023; 13(7):1039
Abstract
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling multisystemic condition. The pathomechanism of ME/CFS remains unestablished; however, impaired natural killer (NK) cell cytotoxicity is a consistent feature of this condition.
Calcium (Ca2+) is crucial for NK cell effector functions. Growing research recognises Ca2+ signalling dysregulation in ME/CFS patients and implicates transient receptor potential ion channel dysfunction.
TRPM7 (melastatin) was recently considered in the pathoaetiology of ME/CFS as it participates in several Ca2+-dependent processes that are central to NK cell cytotoxicity which may be compromised in ME/CFS.
TRPM7-dependent Ca2+ influx was assessed in NK cells isolated from n = 9 ME/CFS patients and n = 9 age- and sex-matched healthy controls (HCs) using live cell fluorescent imaging techniques.
Slope (p < 0.05) was significantly reduced in ME/CFS patients compared with HCs following TRPM7 activation. Half-time of maximal response (p < 0.05) and amplitude (p < 0.001) were significantly reduced in the HCs compared with the ME/CFS patients following TRPM7 desensitisation.
Findings from this investigation suggest that TRPM7-dependent Ca2+ influx is reduced with agonism and increased with antagonism in ME/CFS patients relative to the age- and sex-matched HCs. The outcomes reported here potentially reflect TRPM3 dysfunction identified in this condition suggesting that ME/CFS is a TRP ion channelopathy.
Day H, Yellman B, Hammer S, Rond C, Bell J, Abbaszadeh S, Stoddard G, Unutmaz D, Bateman L and Vernon SD.
Front. Neurosci. 17:1203514
Abstract
Introduction: Cognitive impairment is experienced by people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-acute sequelae of COVID-19 (PASC). Patients report difficulty remembering, concentrating, and making decisions. Our objective was to determine whether orthostatic hemodynamic changes were causally linked to cognitive impairment in these diseases.
Methods: This prospective, observational cohort study enrolled PASC, ME/CFS, and healthy controls. All participants underwent clinical evaluation and assessment that included brief cognitive testing before and after an orthostatic challenge. Cognitive testing measured cognitive efficiency which is defined as the speed and accuracy of subject’s total correct responses per minute.
General linear mixed models were used to analyze hemodynamics and cognitive efficiency during the orthostatic challenge. Additionally, mediation analysis was used to determine if hemodynamic instability induced during the orthostatic challenge mediated the relationship between disease status and cognitive impairment.
Results: Of the 276 participants enrolled, 256 were included in this study (34 PASC, 71 < 4 year duration ME/CFS, 69 > 10 year ME/CFS duration, and 82 healthy controls). Compared to healthy controls, the disease cohorts had significantly lower cognitive efficiency scores immediately following the orthostatic challenge. Cognitive efficiency remained low for the >10 year ME/CFS 2 and 7 days after orthostatic challenge.
Narrow pulse pressure less than 25% of systolic pressure occurred at 4 and 5 min into the orthostatic challenge for the PASC and ME/CFS cohorts, respectively. Abnormally narrow pulse pressure was associated with slowed information processing in PASC patients compared to healthy controls (−1.5, p = 0.04). Furthermore, increased heart rate during the orthostatic challenge was associated with a decreased procedural reaction time in PASC and < 4 year ME/CFS patients who were 40 to 65 years of age.
Discussion: For PASC patients, both their disease state and hemodynamic changes during orthostatic challenge were associated with slower reaction time and decreased response accuracy during cognitive testing. Reduced cognitive efficiency in <4 year ME/CFS patients was associated with higher heart rate in response to orthostatic stress.
Hemodynamic changes did not correlate with cognitive impairment for >10 year ME/CFS patients, but cognitive impairment remained. These findings underscore the need for early diagnosis to mitigate direct hemodynamic and other physiological effects on symptoms of cognitive impairment.
10. Circulating miRNAs Expression in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome
Soffritti I, Gravelsina S, D’Accolti M, Bini F, Mazziga E, Vilmane A, Rasa-Dzelzkaleja S, Nora-Krukle Z, Krumina A, Murovska M, et al.
International Journal of Molecular Sciences. 2023; 24(13):10582.
Abstract
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex multifactorial disease that causes increasing morbidity worldwide, and many individuals with ME/CFS symptoms remain undiagnosed due to the lack of diagnostic biomarkers.
Its etiology is still unknown, but increasing evidence supports a role of herpesviruses (including HHV-6A and HHV-6B) as potential triggers. Interestingly, the infection by these viruses has been reported to impact the expression of microRNAs (miRNAs), short non-coding RNA sequences which have been suggested to be epigenetic factors modulating ME/CFS pathogenic mechanisms.
Notably, the presence of circulating miRNAs in plasma has raised the possibility to use them as valuable biomarkers for distinguishing ME/CFS patients from healthy controls. Thus, this study aimed at determining the role of eight miRNAs, which were selected for their previous association with ME/CFS, as potential circulating biomarkers of the disease.
Their presence was quantitatively evaluated in plasma from 40 ME/CFS patients and 20 healthy controls by specific Taqman assays, and the results showed that six out of the eight of the selected miRNAs were differently expressed in patients compared to controls; more specifically, five miRNAs were significantly upregulated (miR-127-3p, miR-142-5p, miR-143-3p, miR-150-5p, and miR-448), and one was downmodulated (miR-140-5p).
MiRNA levels directly correlated with disease severity, whereas no significant correlations were observed with the plasma levels of seven pro-inflammatory cytokines or with the presence/load of HHV-6A/6B genome, as judged by specific PCR amplification.
The results may open the way for further validation of miRNAs as new potential biomarkers in ME/CFS and increase the knowledge of the complex pathways involved in the ME/CFS development.
Long-COVID Research References
Dr Katrina Pears,
Research Correspondent.
The ME Association.
