Biomarkers for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a systematic review

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multifaceted condition that affects most body systems. There is currently no known diagnostic biomarker; instead, diagnosis is dependent on application of symptom-based case criteria following exclusion of any other potential medical conditions. While there are some studies that report potential biomarkers for ME/CFS, their efficacy has not been validated. The aim of this systematic review is to collate and appraise literature pertaining to a potential biomarker(s) which may effectively differentiate ME/CFS patients from healthy controls.

Methods: This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Cochrane review guidelines. PubMed, Embase and Scopus were systematically searched for articles containing “biomarker” and “ME/CFS” keywords in the abstract or title and if they included the following criteria: (1) were observational studies published between December 1994 and April 2022; (2) involved adult human participants; (3) full text is available in English (4) original research; (5) diagnosis of ME/CFS patients made according to the Fukuda criteria (1994), Canadian Consensus Criteria (2003), International Consensus Criteria (2011) or Institute of Medicine Criteria (2015); (6) study investigated potential biomarkers of ME/CFS compared to healthy controls. Quality and Bias were assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Case Control Studies.

Results: A total of 101 publications were included in this systematic review. Potential biomarkers ranged from genetic/epigenetic (19.8%), immunological (29.7%), metabolomics/mitochondrial/microbiome (14.85%), endovascular/circulatory (17.82%), neurological (7.92%), ion channel (8.91%) and physical dysfunction biomarkers (8.91%). Most of the potential biomarkers reported were blood-based (79.2%). Use of lymphocytes as a model to investigate ME/CFS pathology was prominent among immune-based biomarkers. Most biomarkers had secondary (43.56%) or tertiary (54.47%) selectivity, which is the ability for the biomarker to identify a disease-causing agent, and a moderate (59.40%) to complex (39.60%) ease-of-detection, including the requirement of specialised equipment.

Conclusions: All potential ME/CFS biomarkers differed in efficiency, quality, and translatability as a diagnostic marker. Reproducibility of findings between the included publications were limited, however, several studies validated the involvement of immune dysfunction in the pathology of ME/CFS and the use of lymphocytes as a model to investigate the pathomechanism of illness. The heterogeneity shown across many of the included studies highlights the need for multidisciplinary research and uniform protocols in ME/CFS biomarker research.

Source: Maksoud R, Magawa C, Eaton-Fitch N, Thapaliya K, Marshall-Gradisnik S. Biomarkers for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a systematic review. BMC Med. 2023 May 24;21(1):189. doi: 10.1186/s12916-023-02893-9. PMID: 37226227; PMCID: PMC10206551. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10206551/ (Full text)

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

Abstract:

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.

Source: Xue KY, Quan F, Tang JX, Xiao CH, Lu CX, Cui J. [Bamboo-based medicinal moxibustion for chronic fatigue syndrome: a randomized controlled trial]. Zhongguo Zhen Jiu. 2023 May 12;43(5):493-8. Chinese. PMID: 37161800. https://pubmed.ncbi.nlm.nih.gov/37161800/

Blood group O is associated with post-COVID-19 syndrome in outpatients with a low comorbidity index

Abstract:

Background: ABO blood group system modulates the inflammatory response and has been implicated in COVID-19. Group O protects against SARS-CoV-2 infection, but there are no data regarding post-COVID-19 syndrome (PCS). Our aim was to assess this possible association.

Methods: Case-control study in a community setting, with subjects who had experienced mild COVID-19. Cases were PCS+, controls were PCS-, and the exposure variable, group O. We collected age, sex, BMI, smoking, comorbidities, inflammatory markers, anti-SARS-CoV-2 IgG antibodies, blood type and clinical data. Five composite inflammatory indices were developed. Multivariate analyses were performed.

Results: We analysed 121 subjects (56.2% women), mean age 45.7 ± 16 years. Blood group frequencies were 41.5%, 7.9%, 5.9%, and 44.5% for A, B, AB and O, respectively. Thirty-six patients were PCS+, without significant differences between cases and controls. Compared to non-O, a higher prevalence of PCS (p = .036), and number of symptoms of PCS (p = .017) were noted in group O. Concerning biomarkers, PCS + and PCS- showed no differences in A, B, and AB groups. In contrast, group O PCS + patients had significantly lower albumin-to-globulin ratio and higher lymphocyte count, fibrinogen, CRP levels, and higher percentages of 3 composite indices, than PCS- subjects. Group O showed a 6-fold increased risk of PCS, compared to non-O (adjusted OR = 6.25 [95%CI, 1.6-23]; p = .007).

Conclusions: Group O has shown a consistent relationship with PCS, characterised by a more intense inflammatory burden than the other blood groups. Blood group O could be part of the immunological link between acute COVID-19 and PCS.

Source: Díaz-Salazar S, Navas R, Sainz-Maza L, Fierro P, Maamar M, Artime A, Basterrechea H, Petitta B, Pini S, Olmos JM, Ramos C, Pariente E, Hernández JL. Blood group O is associated with post-COVID-19 syndrome in outpatients with a low comorbidity index. Infect Dis (Lond). 2022 Dec;54(12):897-908. doi: 10.1080/23744235.2022.2115548. Epub 2022 Aug 27. PMID: 36036090. https://www.tandfonline.com/doi/abs/10.1080/23744235.2022.2115548?journalCode=infd20 (Full text)

Cell-Based Blood Biomarkers for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a devastating illness whose biomedical basis is now beginning to be elucidated. We reported previously that, after recovery from frozen storage, lymphocytes (peripheral blood mononuclear cells, PBMCs) from ME/CFS patients die faster in culture medium than those from healthy controls. We also found that lymphoblastoid cell lines (lymphoblasts) derived from these PBMCs exhibit multiple abnormalities in mitochondrial respiratory function and signalling activity by the cellular stress-sensing kinase Target Of Rapamycin Complex 1 (TORC1). These differences were correlated with disease severity, as measured by the Richardson and Lidbury weighted standing test.

The clarity of the differences between these cells derived from ME/CFS patient blood and those from healthy controls suggested that they may provide useful biomarkers for ME/CFS. Here, we report a preliminary investigation into that possibility using a variety of analytical classification tools, including linear discriminant analysis, logistic regression and receiver operating characteristic (ROC) curve analysis.

We found that results from three different tests-lymphocyte death rate, mitochondrial respiratory function and TORC1 activity-could each individually serve as a biomarker with better than 90% sensitivity but only modest specificity vís a vís healthy controls. However, in combination, they provided a cell-based biomarker with sensitivity and specificity approaching 100% in our sample.

This level of sensitivity and specificity was almost equalled by a suggested protocol in which the frozen lymphocyte death rate was used as a highly sensitive test to triage positive samples to the more time consuming and expensive tests measuring lymphoblast respiratory function and TORC1 activity. This protocol provides a promising biomarker that could assist in more rapid and accurate diagnosis of ME/CFS.

Source: Missailidis D, Sanislav O, Allan CY, Annesley SJ, Fisher PR. Cell-Based Blood Biomarkers for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Int J Mol Sci. 2020 Feb 8;21(3). pii: E1142. doi: 10.3390/ijms21031142. https://www.ncbi.nlm.nih.gov/pubmed/32046336

Decreased Expression of the CD57 Molecule in T Lymphocytes of Patients with Chronic Fatigue Syndrome

Abstract:

The chronic fatigue syndrome (CFS) is characterized by a prolonged incapacitating fatigue, headaches, sleep disturbances, and decreases in cognition, besides alterations in other physiological functions. At present, no specific biological markers have been described in this pathology.

In the present study, we analyzed in lymphocytes the CD57 expression for the diagnosis of CFS, evaluating both the percentage of blood lymphocytes expressing CD57 and the average amount of the molecule expressed per cell. The study demonstrated a marked and significant decrease in the expression of CD57 in lymphocytes of CFS patients regarding healthy controls. In T lymphocytes, the decrease was significant both in the percentage of cells expressing CD57 (7.5 ± 1.2 vs 13.3 ± 1.6, p = 0.024) and in a more relevant way in the amount of CD57 molecule expressed per cell (331 ± 59 vs 1003 ± 104, p ≤ 0.0001). In non-T lymphocytes, the decrease was significant only in the amount of CD57 expressed per cell (379 ± 114 vs 691 ± 95, p = 0.007).

The study of CD57 antigen in blood lymphocytes is a useful marker that could cooperate in the diagnosis of CFS patients. Its decrease in T lymphocytes provides most valuable results than the results in other lymphocyte subpopulations.

Source: Espinosa P, Urra JM. Decreased Expression of the CD57 Molecule in T Lymphocytes of Patients with Chronic Fatigue Syndrome. Mol Neurobiol. 2019 Mar 21. doi: 10.1007/s12035-019-1549-7. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/30895436 

Longitudinal associations of lymphocyte subsets with clinical outcomes in chronic fatigue syndrome

Abstract:

BACKGROUND: Chronic fatigue syndrome (CFS) is characterized by prolonged fatigue and other physical and neurocognitive symptoms. Some studies suggest that CFS is accompanied by disruptions in the number and function of various lymphocytes. However, it is not clear which lymphocytes might influence CFS symptoms.

PURPOSE: To determine if patient reported fatigue symptoms and physical functioning scores significantly changed across time with lymphocyte counts as evidence of a relation among chronic fatigue symptoms and the immune response.

METHODS: The current longitudinal, naturalistic study assessed the cellular expression of three lymphocyte subtypes — natural killer (NK) cells (CD3-CD16+ and CD3-CD56+) and naïve T cells (CD4+CD45RA+) — to determine whether changes in lymphocytes at 4 time points across 18 months were associated with clinical outcomes, including CFS symptoms, physical functioning, and vitality, among patients with chronic fatigue.. Latent growth curve models were used to examine the longitudinal relationship between lymphocytes and clinical outcomes.

RESULTS: Ninety-three patients with Fukuda-based CFS and seven with non-CFS fatigue provided study data. Results indicated that higher proportions of naïve T cells and lower proportions of NK cells were associated with worse physical functioning, whereas higher proportions of NK cells (CD3-CD16+) and lower proportions of naïve T cells were associated with fewer CFS symptoms.

CONCLUSION: These findings suggest that lymphocytes are modestly related to clinical outcomes over time.

Source: Mehalick ML, Schmaling KB, Sabath DE, Buchwald DS. Longitudinal associations of lymphocyte subsets with clinical outcomes in chronic fatigue syndrome. Fatigue. 2018;6(2):80-91. doi: 10.1080/21641846.2018.1426371. Epub 2018 Jan 12.  https://www.ncbi.nlm.nih.gov/pubmed/30112249

Longitudinal associations of lymphocyte subsets with clinical outcomes in chronic fatigue syndrome

Abstract:

Background: Chronic fatigue syndrome (CFS) is characterized by prolonged fatigue and other physical and neurocognitive symptoms. Some studies suggest that CFS is accompanied by disruptions in the number and function of various lymphocytes. However, it is not clear which lymphocytes might influence CFS symptoms.

Purpose: To determine if patient reported fatigue symptoms and physical functioning scores significantly changed across time with lymphocyte counts as evidence of a relation among chronic fatigue symptoms and the immune response.

Methods: The current longitudinal, naturalistic study assessed the cellular expression of three lymphocyte subtypes – natural killer (NK) cells (CD3 − CD16+ and CD3 − CD56+) and naïve T cells (CD4 + CD45RA+) – to determine whether changes in lymphocytes at 4 time points across 18 months were associated with clinical outcomes, including CFS symptoms, physical functioning, and vitality, among patients with chronic fatigue. Latent growth curve models were used to examine the longitudinal relationship between lymphocytes and clinical outcomes.

Results: Ninety-three patients with Fukuda-based CFS and seven with non-CFS fatigue provided study data. Results indicated that higher proportions of naïve T cells and lower proportions of NK cells were associated with worse physical functioning, whereas higher proportions of NK cells (CD3 − CD16+) and lower proportions of naïve T cells were associated with fewer CFS symptoms.

Conclusion: These findings suggest that lymphocytes are modestly related to clinical outcomes over time.

Source: Melissa L. Mehalick, Karen B. Schmaling, Daniel E. Sabath & Dedra S.Buchwald. Longitudinal associations of lymphocyte subsets with clinical outcomes in chronic fatigue syndrome. Fatigue: Biomedicine, Health & Behavior, Published online: 12 Jan 2018. http://www.tandfonline.com/action/showCitFormats?doi=10.1080%2F21641846.2018.1426371

Unperturbed Cytotoxic Lymphocyte Phenotype and Function in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

Abstract:

Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is a debilitating disorder linked to diverse intracellular infections as well as physiological stress. Cytotoxic lymphocytes combat intracellular infections. Their function is attenuated by stress. Despite numerous studies, the role of cytotoxic lymphocytes in ME/CFS remains unclear. Prompted by advances in the understanding of defects in lymphocyte cytotoxicity, the discovery of adaptive natural killer (NK) cell subsets associated with certain viral infections, and compelling links between stress, adrenaline, and cytotoxic lymphocyte function, we reassessed the role of cytotoxic lymphocytes in ME/CFS.

Forty-eight patients from two independent cohorts fulfilling the Canada 2003 criteria for ME/CFS were evaluated with respect to cytotoxic lymphocyte phenotype and function. Results were compared to values from matched healthy controls. Reproducible differences between patients and controls were not found in cytotoxic lymphocyte numbers, cytotoxic granule content, activation status, exocytotic capacity, target cell killing, or cytokine production. One patient expressed low levels of perforin, explained by homozygosity for the PRF1 p.A91V variant. However, overall, this variant was present in a heterozygous state at the expected population frequency among ME/CFS patients.

No single patient displayed any pathological patterns of cellular responses. Increased expansions of adaptive NK cells or deviant cytotoxic lymphocyte adrenaline-mediated inhibition were not observed. In addition, supervised dimensionality reduction analyses of the full, multidimensional datasets did not reveal any reproducible patient/control discriminators.

In summary, employing sensitive assays and analyses for quantification of cytotoxic lymphocyte differentiation and function, cytotoxicity lymphocyte aberrances were not found among ME/CFS patients. These assessments of cytotoxic lymphocytes therefore do not provide useful biomarkers for the diagnosis of ME/CFS.

Source: Theorell J, Bileviciute-Ljungar I, Tesi B, Schlums H, Johnsgaard MS, Asadi-Azarbaijani B, Bolle Strand E, Bryceson YT. Unperturbed Cytotoxic Lymphocyte Phenotype and Function in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients. Front Immunol. 2017 Jun 26;8:723. doi: 10.3389/fimmu.2017.00723. eCollection 2017. http://journal.frontiersin.org/article/10.3389/fimmu.2017.00723/full (Full article)

Graded versus Intermittent Exercise Effects on Lymphocytes in Chronic Fatigue Syndrome

Abstract:

PURPOSE: There is increasing evidence of immune system dysfunction in chronic fatigue syndrome (CFS), but little is known of the regular exercise effects on immune cell parameters. This pilot study investigated the effects of graded and intermittent exercise on CD4 lymphocyte subset counts and activation compared with usual care.

METHODS: Twenty-four CFS patients (50.2 ± 10 yr) were randomized to graded exercise (GE), intermittent exercise (IE), or usual care (UC) groups; 18 sedentary non-CFS participants (50.6 ± 10 yr) were controls (CTL) for blood and immunological comparisons. Outcome measures were pre- and postintervention flow cytometric analyses of circulating lymphocyte subset cell counts; expression of CD3, CD4, CD25, and CD134; full blood counts; and V˙O2peak.

RESULTS: Preintervention, CD3 cell counts, and expression of CD4, CD25, CD134, and CD4CD25CD134 were significantly lower in GE, IE, and UC compared with CTL (P < 0.05). Total lymphocyte concentration was significantly lower in GE and IE groups compared with CTL. There were significant postintervention increases in i) expression of CD4 and CD4CD25CD134 for GE and IE, but CD25 and CD134 for IE only; ii) circulating counts of CD3 and CD4 for GE, and CD3, CD4, CD8, CD3CD4CD8, CD3CD16CD56, CD19, and CD45 for IE; iii) neutrophil concentration for GE; and iv) V˙O2peak and elapsed test time for IE and GE, V˙Epeak for IE.

CONCLUSIONS: Twelve weeks of GE and IE training significantly improved CD4 lymphocyte activation and aerobic capacity without exacerbating CFS symptoms. IE may be a more effective exercise modality with regard to enhanced CD4 activation in CFS patients.

 

Source: Broadbent S, Coutts R. Graded versus Intermittent Exercise Effects on Lymphocytes in Chronic Fatigue Syndrome. Med Sci Sports Exerc. 2016 Sep;48(9):1655-63. doi: 10.1249/MSS.0000000000000957. https://www.ncbi.nlm.nih.gov/pubmed/27116645

 

Effects of exercise on behavior and peripheral blood lymphocyte apoptosis in a rat model of chronic fatigue syndrome

Abstract:

This study examined the effects of exercise on behavior and peripheral blood leukocyte apoptosis in a rat model of chronic fatigue syndrome (CFS).

Thirty-six healthy male Sprague-Dawley rats were equally randomized into 3 groups: the control group, CFS model group and the exercise group in terms of body weight. A total of 25 rats entered the final statistical analysis due to 11 deaths during the study. CFS model was established by subjecting the rats in CFS model group and exercise group to electric shock, chronic restraint stress and cold water swim. Besides, rats in the exercise group took running wheel exercise.

After a week of conditioning feeding, model construction and running wheel exercise were performed simultaneously, and lasted for 23 consecutive days. The behavior experiments, including running wheel exercise, open-field test, tail suspension test and Morris water maze test, were conducted, either before or after the model establishment. Rats were sacrificed and peripheral blood was obtained for the assessment of lymphocyte apoptosis index by flow cytometry (FCM).

It was found that as compared with those in the control group, the weight of the rats was decreased obviously (P<0.01), the mobility time in the open-field and the tail suspension tests was shortened significantly (P<0.01), the time to locate the platform was enhanced (P<0.01) and the cell apoptosis index was increased substantially (P<0.01) in the CSF model group.

Meanwhile, in comparison to the model group, the behavior in the open-field and the tail suspension tests was improved significantly (P<0.05), and the apoptosis index decreased remarkably (P<0.01) in the exercise group. It is concluded that sport intervention can prevent lymphocyte apoptosis and improve animal behavior rather than the memory.

 

Source: Zou J, Yuan J, Lv S, Tu J. Effects of exercise on behavior and peripheral blood lymphocyte apoptosis in a rat model of chronic fatigue syndrome. J Huazhong Univ Sci Technolog Med Sci. 2010 Apr;30(2):258-64. doi: 10.1007/s11596-010-0225-y. Epub 2010 Apr 21. https://www.ncbi.nlm.nih.gov/pubmed/20407885