Category: Pathophysiology

Advances in Understanding the Pathophysiology of Chronic Fatigue Syndrome

Introduction:

The illness now called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) was first described in the mid-1980s. At that time, nothing was known about its underlying biology. Indeed, because many standard laboratory test results were normal, some clinicians explained to patients that “there is nothing wrong.” There was, of course, an alternative explanation: the standard laboratory tests might not have been the right tests to identify the underlying abnormalities.

Over the past 35 years, thousands of studies from laboratories in many countries have documented underlying biological abnormalities involving many organ systems in patients with ME/CFS, compared with healthy controls: in short, there is something wrong. Moreover, most of the abnormalities are not detected by standard laboratory tests. In 2015, the Institute of Medicine of the National Academy of Sciences concluded that ME/CFS “is a serious, chronic, complex systemic disease that often can profoundly affect the lives of patients,” affects up to an estimated 2.5 million people in the United States, and generates direct and indirect expenses of approximately $17 billion to $24 billion annually.

Read the rest of this article HERE.

Source: Anthony L. Komaroff, MD. Advances in Understanding the Pathophysiology of Chronic Fatigue Syndrome. JAMA. Published online July 5, 2019. doi:10.1001/jama.2019.8312 https://jamanetwork.com/journals/jama/fullarticle/2737854 (Full article)

Understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and the Emerging Osteopathic Approach: A Narrative Review

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating syndrome of unknown origin, characterized by profound postexertional malaise and fatigue, unrefreshing sleep, cognitive impairments, immune dysfunction, pain, autonomic dysfunction, and neuroendocrine symptoms. Although ME/CFS is well documented within the medical literature, it remains difficult to diagnosis and manage.

Some of the current challenges include an absence of diagnostic markers, differing diagnostic criteria, and an overall lack of awareness within the medical community. As a result, patients are often frustrated by the difficulties in acquiring a diagnosis and from the overall lack of available treatments. In an effort to increase awareness, this review discusses disease pathophysiology, clinical presentation, and treatment options, while also highlighting the benefits of an osteopathic approach.

J Am Osteopath Assoc. 2019 Jul 1;119(7):446-455. doi: 10.7556/jaoa.2019.081.

Source: Larrimore C, Ramnot A, Jaghab A, Sarduy S, Guerrero G, Troccoli P, Hilton K, Bested A. Understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and the Emerging Osteopathic Approach: A Narrative Review. J Am Osteopath Assoc. 2019 Jul 1;119(7):446-455. doi: 10.7556/jaoa.2019.081. https://www.ncbi.nlm.nih.gov/pubmed/31233110

MtDNA population variation in Myalgic encephalomyelitis/Chronic fatigue syndrome in two populations: a study of mildly deleterious variants

Abstract:

Myalgic Encephalomyelitis (ME), also known as Chronic Fatigue Syndrome (CFS) is a debilitating condition. There is growing interest in a possible etiologic or pathogenic role of mitochondrial dysfunction and mitochondrial DNA (mtDNA) variation in ME/CFS. Supporting such a link, fatigue is common and often severe in patients with mitochondrial disease.

We investigate the role of mtDNA variation in ME/CFS. No proven pathogenic mtDNA mutations were found. We then investigated population variation. Two cohorts were analysed, one from the UK (n = 89 moderately affected; 29 severely affected) and the other from South Africa (n = 143 moderately affected). For both cohorts, ME/CFS patients had an excess of individuals without a mildly deleterious population variant. The differences in population variation might reflect a mechanism important to the pathophysiology of ME/CFS.

Source: Venter M, Tomas C, Pienaar IS, Strassheim V, Erasmus E, Ng WF, Howell N, Newton JL, Van der Westhuizen FH, Elson JL. MtDNA population variation in Myalgic encephalomyelitis/Chronic fatigue syndrome in two populations: a study of mildly deleterious variants. Sci Rep. 2019 Feb 27;9(1):2914. doi: 10.1038/s41598-019-39060-1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6393470/ (Full article)

Altered Erythrocyte biophysical properties in Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multi-systemic illness of unknown etiology affecting millions of individuals worldwide. In this work, we tested the hypothesis that erythrocyte biophysical properties are adversely affected in ME/CFS.

We tested erythrocyte deformability using a high-throughput microfluidic device which mimics microcapillaries. We perfused erythrocytes from ME/CFS patients and from age and sex matched healthy controls (n=14 pairs of donors) through a high-throughput microfluidic platform (5μmx5μm). We recorded cell movement at high speed (4000 fps), followed by image analysis to assess the following parameters: entry time (time required by cells to completely enter the test channels), average transit velocity (velocity of cells inside the test channels) and elongation index (ratio of the major diameter before and after deformation in the test channel). We observed that erythrocytes from ME/CFS patients had higher entry time, lower average transit velocity and lower elongation index as compared to healthy controls.

Taken together, this data shows that erythrocytes from ME/CFS patients have reduced deformability. To corroborate our findings, we measured the erythrocyte sedimentation rate for these donors which show that the erythrocytes from ME/CFS patients had lower sedimentation rates. To understand the basis for differences in deformability, we investigated changes in the fluidity of the membrane using pyrenedecanoic acid and observed that erythrocytes from ME/CFS patients have lower membrane fluidity. Zeta potential measurements showed that ME/CFS patients had lower net negative surface charge on the erythrocyte plasma membrane. Higher levels of reactive oxygen species in erythrocytes from ME/CFS patients were also observed. Using scanning electron microscopy, we also observed changes in erythrocyte morphology between ME/CFS patients and healthy controls.

Finally, preliminary studies show that erythrocytes from “recovering” ME/CFS patients do not show such differences, suggesting a connection between erythrocyte deformability and disease severity.

Source: Amit K. Saha, Brendan R. Schmidt, Julie Wilhelmy, Vy Nguyen, Justin K. Do, Vineeth C. Suja, Mohsen Nemat-Gorgani, Anand K. Ramasubramanian, Ronald W. Davis. Altered Erythrocyte Biophysical Properties in Chronic Fatigue Syndrome. Biophys. Journal. VOLUME 116, ISSUE 3, SUPPLEMENT 1, 122A, FEBRUARY 15, 2019. https://www.cell.com/biophysj/fulltext/S0006-3495(18)31946-5

Changes in the transcriptome of circulating immune cells of a New Zealand cohort with myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a poorly understood disease affecting 0.2%-2% of the global population. To gain insight into the pathophysiology of ME/CFS in New Zealand, we examined the transcriptomes of peripheral blood mononuclear cells by RNA-seq analysis in a small well-characterized patient group (10 patients), with age/gender-matched healthy controls (10 control subjects).

Twenty-seven gene transcripts were increased 1.5- to sixfold and six decreased three- to sixfold in the patient group ( P < 0.01). The top enhanced gene transcripts, IL8, NFΚBIA and TNFAIP3, are functionally related to inflammation, and significant changes were validated for IL8 and NFΚBIA by quantitative polymerase chain reaction (qPCR). Functional network analysis of the altered gene transcripts ( P < 0.01) detected interactions between the products related to inflammation, circadian clock function, metabolic dysregulation, cellular stress responses and mitochondrial function. Ingenuity pathway analysis ( P < 0.05) provided further insights into the dysfunctional physiology, highlighting stress and inflammation pathways.

This analysis provides novel insights into the molecular changes in ME/CFS and contributes to the understanding of the pathophysiological mechanisms of the disease.

Source: Sweetman E, Ryan M, Edgar C, MacKay A, Vallings R, Tate W. Changes in the transcriptome of circulating immune cells of a New Zealand cohort with myalgic encephalomyelitis/chronic fatigue syndrome. Int J Immunopathol Pharmacol. 2019 Jan-Dec;33:2058738418820402. doi: 10.1177/2058738418820402.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350121/ (Full article)

Myalgic encephalomyelitis or chronic fatigue syndrome: how could the illness develop?

Abstract:

A model of the development and progression of chronic fatigue syndrome (myalgic encephalomyelitis), the aetiology of which is currently unknown, is put forward, starting with a consideration of the post-infection role of damage-associated molecular patterns and the development of chronic inflammatory, oxidative and nitrosative stress in genetically predisposed individuals.

The consequences are detailed, including the role of increased intestinal permeability and the translocation of commensal antigens into the circulation, and the development of dysautonomia, neuroinflammation, and neurocognitive and neuroimaging abnormalities. Increasing levels of such stress and the switch to immune and metabolic downregulation are detailed next in relation to the advent of hypernitrosylation, impaired mitochondrial performance, immune suppression, cellular hibernation, endotoxin tolerance and sirtuin 1 activation.

The role of chronic stress and the development of endotoxin tolerance via indoleamine 2,3-dioxygenase upregulation and the characteristics of neutrophils, monocytes, macrophages and T cells, including regulatory T cells, in endotoxin tolerance are detailed next. Finally, it is shown how the immune and metabolic abnormalities of chronic fatigue syndrome can be explained by endotoxin tolerance, thus completing the model.

Source: Gerwyn Morris, Michael Maes, Michael Berk, Basant K. Puri. Myalgic encephalomyelitis or chronic fatigue syndrome: how could the illness develop? Metabolic Brain Disease. Review Article, First Online: 13 February 2019 https://doi.org/10.1007/s11011-019-0388-6 (Full article)

Red blood cell deformability is diminished in patients with Chronic Fatigue Syndrome

[Editor’s comment: Conspicuously absent from the reference section in this paper is the pioneering work of L. O. Simpson. In 1989 Dr. Leslie O. Simpson, a New Zealand pathologist, discovered that the blood of people with ME/CFS tends to have a higher proportion of cup-shaped red blood cells. (Simpson, L.O. “Nondiscocyte Erythrocytes in Myalgic Encephalomyelitis.” New Zealand Medical Journal 2(864):126-127,1989.) Cup-shaped cells are more difficult to squeeze through small capillaries than disc-shaped cells, making it harder for blood to oxygenate capillary-dependent tissues. In further investigations, Dr. Simpson also observed similar changes in red blood cell morphology in other diseases. He noted that red blood cell shape can change from minute to minute. A summary of Dr. Simpson’s work on red blood cell morphology in ME/CFS can be found HERE.]

Abstract:

BACKGROUND: Myalgic encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a poorly understood disease. Amongst others symptoms, the disease is associated with profound fatigue, cognitive dysfunction, sleep abnormalities, and other symptoms that are made worse by physical or mental exertion. While the etiology of the disease is still debated, evidence suggests oxidative damage to immune and hematological systems as one of the pathophysiological mechanisms of the disease. Since red blood cells (RBCs) are well-known scavengers of oxidative stress, and are critical in microvascular perfusion and tissue oxygenation, we hypothesized that RBC deformability is adversely affected in ME/CFS.

METHODS: We used a custom microfluidic platform and high-speed microscopy to assess the difference in deformability of RBCs obtained from ME/CFS patients and age-matched healthy controls.

RESULTS AND CONCLUSION: We observed from various measures of deformability that the RBCs isolated from ME/CFS patients were significantly stiffer than those from healthy controls. Our observations suggest that RBC transport through microcapillaries may explain, at least in part, the ME/CFS phenotype, and promises to be a novel first-pass diagnostic test

Source: Saha KA, Schmidt RB, Wilhelmy J, Nguyen V, Abugherir A, Do KJ, Nemat-Gorgani M, Davis WR, Ramasubramanian KA. Red blood cell deformability is diminished in patients with Chronic Fatigue Syndrome.Clin Hemorheol Microcirc. 2018 Dec 28. doi: 10.3233/CH-180469. [Epub ahead of print]  https://content.iospress.com/articles/clinical-hemorheology-and-microcirculation/ch180469 (Full article)

Peak Oxygen Uptake in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis: A Meta-Analysis

Abstract:

To evaluate the magnitude of the difference in VO2peak between patients with Chronic Fatigue Syndrome/ Myalgic Encephalomyelitis (CFS/ME) and apparently healthy controls, 7 databases (Cochrane, PubMed, PsycINFO, Web of Knowledge, Embase, Scopus, Medline) were searched for articles published up to March 2018. Search terms included “chronic fatigue syndrom*”AND (“peak” OR “maxim*” OR “max”) AND (“oxygen uptake” OR “oxygen consumption” OR “VO2peak” or “VO2max”.

Eligibility criteria were adults>18 y with clinically diagnosed CFS/ME, with VO2peak measured in a maximal test and compared against an apparently healthy control group. The methodological quality of included studies was assessed using a modified Systematic Appraisal of Quality for Observational Research critical appraisal framework. A random effects meta-analysis was conducted on 32 cross-sectional studies (effects).

Pooled mean VO2peak was 5.2 (95% CI: 3.8-6.6) ml.kg-1min-1 lower in CFS/ME patients vs. healthy controls. Between-study variability (Tau) was 3.4 (1.5-4.5) ml.kg-1min-1 indicating substantial heterogeneity. The 95% prediction interval was -1.9 to 12.2 ml.kg-1min-1. The probability that the effect in a future study would be>the minimum clinically important difference of 1.1 ml.kg-1min-1 (in favour of controls) was 0.88 – likely to be clinically relevant. Synthesis of the available evidence indicates that CFS/ME patients have a substantially reduced VO2peak compared to controls.

Source: Franklin JD, Atkinson 1, Atkinson JM, Batterham AM. Peak Oxygen Uptake in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis: A Meta-Analysis. Int J Sports Med. 2018 Dec 17. doi: 10.1055/a-0802-9175. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/30557887

A systematic review of enteric dysbiosis in chronic fatigue syndrome/myalgic encephalomyelitis

Abstract:

BACKGROUND: Chronic fatigue syndrome or myalgic encephalomyelitis (CFS/ME) is an illness characterised by profound and pervasive fatigue in addition to a heterogeneous constellation of symptoms. The aetiology of this condition remains unknown; however, it has been previously suggested that enteric dysbiosis is implicated in the pathogenesis of CFS/ME. This review examines the evidence currently available for the presence of abnormal microbial ecology in CFS/ME in comparison to healthy controls, with one exception being probiotic-supplemented CFS/ME patients, and whether the composition of the microbiome plays a role in symptom causation.

METHODS: EMBASE, Medline (via EBSCOhost), Pubmed and Scopus were systematically searched from 1994 to March 2018. All studies that investigated the gut microbiome composition of CFS/ME patients were initially included prior to the application of specific exclusion criteria. The association between these findings and patient-centred outcomes (fatigue, quality of life, gastrointestinal symptoms, psychological wellbeing) are also reported.

RESULTS: Seven studies that met the inclusion criteria were included in the review. The microbiome composition of CFS/ME patients was compared with healthy controls, with the exception of one study that compared to probiotic-supplemented CFS/ME patients. Differences were reported in each study; however, only three were considered statistically significant, and the findings across all studies were inconsistent. The quality of the studies included in this review scored between poor (< 54%), fair (54-72%) and good (94-100%) using the Downs and Black checklist.

CONCLUSIONS: There is currently insufficient evidence for enteric dysbiosis playing a significant role in the pathomechanism of CFS/ME. Recommendations for future research in this field include the use of consistent criteria for the diagnosis of CFS/ME, reduction of confounding variables by controlling factors that influence microbiome composition prior to sample collection and including more severe cases of CFS/ME.

Source: Du Preez S, Corbitt M, Cabanas H, Eaton N, Staines D, Marshall-Gradisnik S. A systematic review of enteric dysbiosis in chronic fatigue syndrome/myalgic encephalomyelitis. Syst Rev. 2018 Dec 20;7(1):241. doi: 10.1186/s13643-018-0909-0. https://systematicreviewsjournal.biomedcentral.com/articles/10.1186/s13643-018-0909-0 (Full article)

The UK ME/CFS Biobank: A Disease-Specific Biobank for Advancing Clinical Research Into Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling disease characterized by unexplained incapacitating fatigue, accompanied by variable multi-systemic symptoms. ME/CFS causes a significant personal and public health burden, and urgently requires the coordination of research efforts to investigate its etiology and pathophysiology and to develop and validate sensitive and specific biomarkers to confirm diagnosis.

This narrative paper describes how people with ME/CFS, together with a multidisciplinary team of researchers, have established the UK ME/CFS Biobank (UKMEB), a unique research infrastructure specifically designed to expedite biomedical research into ME/CFS. We describe the journey that led to its conceptualization and operation, and how the resource has served as a model disease-specific biobank, aggregating human biospecimens alongside comprehensive health information on participants.

The UKMEB currently has data and samples from 600 donors including people with ME/CFS and a comparison group with multiple sclerosis and healthy controls. A longitudinal sub-cohort has been established of participants having follow-up assessments at multiple time-points. As an open resource for quality and ethical research into ME/CFS, biological samples and data have not only been analyzed within our research team but have also been shared with researchers across Europe, America and the Middle East. We continue to encourage researchers from academic and commercial sectors to access the UKMEB. Major steps have been taken and challenges remain; these include sustainability and expansion, and harmonization of processes to facilitate integration with other bioresources and databanks internationally.

Source: Lacerda EM, Mudie K, Kingdon CC, Butterworth JD, O’Boyle S, Nacul L. The UK ME/CFS Biobank: A Disease-Specific Biobank for Advancing Clinical Research Into Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Front Neurol. 2018 Dec 4;9:1026. doi: 10.3389/fneur.2018.01026.
eCollection 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288193/ (Full article)