Category: Pathophysiology

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

Abstract:

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.
Source: Gottschalk CG, Whelan R, Peterson D, Roy A. Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study. International Journal of Molecular Sciences. 2023; 24(10):8713. https://doi.org/10.3390/ijms24108713 (Full text)

Modulation of Beta-Adrenergic Autoantibodies Over Time in Post-Viral ME/CFS is Related to Fatigue and Pain Symptoms

Abstract:

Background: Myalgic encephalomyelits/chronic fatigue syndrome (ME/CFS) is an acquired disease with symptoms of fatigue and pain. In pathogenesis, the induction of autoantibodies (AAB) against G-protein coupled receptors (GPCR), such as β-adrenergic receptors (β-AdR), has been suspected. GPCR-AAB correlate with symptom severity and autonomic dysfunction in ME/CFS.

Objectives: To describe symptoms and treatment of a patient presenting with infection-triggered ME/CFS demonstrating that levels of β-AdR-AAB underlie modulation over time, correlating with the severity of symptoms.

Methods: At T1 and T2, GPCR-AAB were measured and questionnaires assessing symptom severity were completed. TSHDS-IgM-AAB were tested, and SF density was analyzed via skin probe.

Results: At T2, elevated levels of β-AdR-AAB were found, corresponding with an aggravation of fatigue and pain symptoms. Elevated TSHDS-IgM-AAB were found, which corresponded with reduced fiber density from the skin probe.

Conclusions: The levels of β-AdR-AAB in post-infectious ME/CFS can be modulated. Future studies might target interventions to reduce these AAB.

Source: Busch L, Schriek C, Paul M, Heidecke H. Modulation of Beta-Adrenergic Autoantibodies Over Time in Post-Viral ME/CFS is Related to Fatigue and Pain Symptoms. Isr Med Assoc J. 2023 Apr;25(4):259-264. PMID: 37129123. https://pubmed.ncbi.nlm.nih.gov/37129123/

Suppressed immune and metabolic responses to intestinal damage-associated microbial translocation in myalgic encephalomyelitis/chronic fatigue syndrome

Highlights:

  • Elevation of FABP2, a marker of intestinal cell damage in ME/CFS.
  • Absence of optimal acute-phase LBP and sCD14 anti-microbial responses in ME/CFS.
  • Compensatory but inadequate B cell response to microbial translocation in ME/CFS.
  • Enhanced IL-10 regulatory response may drive the observed immunosuppression.
  • Glucose and citrate metabolic dysfunction in ME/CFS may link the IL-10 activation and suppressed anti-microbial responses.

Abstract:

The etiology and mechanism of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are poorly understood and no biomarkers have been established. Specifically, the relationship between the immunologic, metabolic, and gastrointestinal abnormalities associated with ME/CFS and their relevance to established symptoms of the condition remain unclear.

Relying on data from two independent cohorts of ME/CFS and control study participants, one at rest and one undergoing an exercise challenge, we identify a state of suppressed acute-phase innate immune response to microbial translocation in conjunction with a compromised gut epithelium. This immunosuppression, along with observed enhancement of compensatory antibody responses to counter the microbial translocation, was associated with and may be mediated by alterations in glucose and citrate metabolism and an IL-10 immunoregulatory response. Our findings provide novel insights into mechanistic pathways, biomarkers, and potential therapeutic targets in ME/CFS, including in the context of exertion, with relevance to both intestinal and extra-intestinal symptoms.

Source: Melanie Uhde, Alyssa C. Indart, Peter H.R. Green, Robert H. Yolken, Dane B. Cook, Sanjay K. Shukla, Suzanne D. Vernon, Armin Alaedini.
Suppressed immune and metabolic responses to intestinal damage-associated microbial translocation in myalgic encephalomyelitis/chronic fatigue syndrome. Brain, Behavior, & Immunity – Health, 2023, 100627. ISSN 2666-3546, https://doi.org/10.1016/j.bbih.2023.100627.
https://www.sciencedirect.com/science/article/pii/S2666354623000418 (Full text)

Exploring the Genetic Contribution to Oxidative Stress in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

OBJECTIVES/GOALS: Strong evidence has implicated oxidative stress (OS) as a disease mechanism in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The study aim was to assess whether a C>T single nucleotide polymorphism (SNP) (rs1800668), which reduces the activity of glutathione peroxidase 1 (GPX1), is associated with brain OS in patients with ME/CFS.

METHODS/STUDY POPULATION: Study population: The study enrolled 20 patients with ME/CFS diagnosed according to Canadian Consensus Criteria, and 11 healthy control (HC) subjects. Genotyping: DNA was extracted from whole blood samples, amplified by PCR, and purified. Sanger sequencing was used for genotyping. 1H MRS: Proton magnetic resonance spectroscopy (1H MRS) was used to measure levels of glutathione (GSH) a primary tissue antioxidant and OS marker in a 3x3x2 cm3 occipital cortex (OCC) voxel. GSH spectra were recorded in 15 minutes with the standard J-editing technique. The resulting GSH peak area was normalized to tissue water level in the voxel. Statistical Analysis: T-tests were used to compare OCC GSH levels between ME/CFS and HC groups, and between the study’s genotype groups (group 1: CC, group 2: combined TC and TT).

RESULTS/ANTICIPATED RESULTS: Clinical characteristics: ME/CFS and HC groups were comparable on age and BMI but not on sex (p = 0.038). Genotype frequencies: Genotype frequencies in the ME/CFS group were 0.55 (CC), 0.25 (TC) and 0.2 (TT); and 0.636 (CC), 0.364 (TC), and 0 (TT) in the HC group. GSH levels: There was a trend-level lower mean OCC GSH in ME/CFS than in HC (0.0015 vs 0.0017; p = 0.076). GSH levels by genotype group interaction: Within the ME/CFS group but not in the combined ME/CFS and HC group or HC group alone, GSH levels were lower in the TC and TT genotypes than in CC genotypes (0.00143 vs 0.00164; p = 0.018).

DISCUSSION/SIGNIFICANCE: This study found that the presence of a C>T SNP in GPX1 is associated with lower mean GSH levels and, hence, brain oxidative stress, in ME/CFS patients. If validated in a larger cohort, this finding may support targeted antioxidant therapy based on their genotype as a potentially effective treatment for patients with ME/CFS.

Source: Hampilos, N., Germain, A., Mao, X., Hanson, M., & Shungu, D. (2023). 474 Exploring the Genetic Contribution to Oxidative Stress in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Journal of Clinical and Translational Science, 7(S1), 137-138. doi:10.1017/cts.2023.488. DOI: https://doi.org/10.1017/cts.2023.488

LC, POTS, and ME/CFS: Lifting the Fog

Abstract:

These three syndromes – long covid (LC), postural orthostatic tachycardia syndrome (POTS), and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) – have many symptoms in common. The common denominator remains elusive.
The blood brain barrier (BBB) has been a barrier not only to microbes and toxins but also to understanding pathogenetic links. There are several areas within the brain that have no BBB. These are known as circumventricular organs (CVOs) and their location relative to CNS nuclei that direct autonomic and neuroendocrine functions is provocative in the quest for pathogenesis.
In addition the majority afflicted with LC and ME/CFS appear to be those with two MTHFR polymorphisms, present in over 50% of Americans. These polymorphisms elevate homocysteine. When homocysteine is combined with CVOs, the fog of POTS and its paradox are lifted. POTS may represent the intersection of LC and ME/CFS in those with the MTHFR gene (hypermethylation or 677TT).
The gut microbiomes of LC and ME/CFS, deficient in butyrates, GABA, and diversity, are then linked with MTHFR genotype 677TT. Reactivation of neurotropic EBV and VZV, due to loss of surveillance by CD4+/CD8+ T cells, is seen as secondary. The oxidative stress generated by homocysteine, loss of glutathione, low fiber diet, and persistent chronic inflammation exhaust available mitochondria and, assisted by BKN and estrogen, exacerbate all the elements of these post viral fatigue syndromes.
Source: Chambers, P. LC, POTS, and ME/CFS: Lifting the Fog. Preprints.org 2023, 2023030418. https://doi.org/10.20944/preprints202303.0418.v1 (Full text available as PDF file)

Cardiovascular and haematological pathology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): A role for viruses

Abstract:

ME/CFS is a debilitating chronic condition that often develops after viral or bacterial infection. Insight from the study of Long COVID/Post Acute Sequelae of COVID-19 (PASC), the post-viral syndrome associated with SARS-CoV-2 infection, might prove to be useful for understanding pathophysiological mechanisms of ME/CFS. Disease presentation is similar between the two conditions, and a subset of Long COVID patients meet the diagnostic criteria for ME/CFS.

Since Long COVID is characterized by significant vascular pathology – including endothelial dysfunction, coagulopathy, and vascular dysregulation – the question of whether or not the same biological abnormalities are of significance in ME/CFS arises.

Cardiac abnormalities have for a while now been documented in ME/CFS cohorts, with recent studies demonstrating major deficits in cerebral blood flow, and hence vascular dysregulation. A growing body of research is demonstrating that ME/CFS is accompanied by platelet hyperactivation, anomalous clotting, a procoagulant phenotype, and endothelial dysfunction. Endothelial damage and dysregulated clotting can impair substance exchange between blood and tissues, and result in hypoperfusion, which may contribute to the manifestation of certain ME/CFS symptoms.

Here we review the ME/CFS literature to summarize cardiovascular and haematological findings documented in patients with the condition, and, in this context, briefly discuss the potential role of previously-implicated pathogens.

Overall, cardiac and haematological abnormalities are present within ME/CFS cohorts. While atherosclerotic heart disease is not significantly associated with ME/CFS, suboptimal cardiovascular function defined by reduced cardiac output, impaired cerebral blood flow, and vascular dysregulation are, and these abnormalities do not appear to be influenced by deconditioning. Rather, these cardiac abnormalities may result from dysfunction in the (autonomic) nervous system.

Plenty of recently published studies are demonstrating significant platelet hyperactivity and endothelial dysfunction in ME/CFS, as well as anomalous clotting processes. It is of particular importance to determine to what extent these cardiovascular and haematological abnormalities contribute to symptom severity, and if these two systems can be targeted for therapeutic purposes.

Viral reservoirs of herpesviruses exist in ME/CFS, and most likely contribute to cardiovascular and haematological dysfunction directly or indirectly. This review highlights the potential of studying cardiac functioning, the vasculature, and coagulation system in ME/CFS.

Source: Jean M. Nunes, Douglas B. Kell, Etheresia Pretorius. Cardiovascular and haematological pathology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): A role for viruses. Blood reviews, 20 March 2023, 101075 [Epub ahead of print]  https://www.sciencedirect.com/science/article/pii/S0268960X2300036X (Full text)

Altered Fatty Acid Oxidation in Lymphocyte Populations of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling multisystem illness in which individuals are plagued with fatigue, inflammatory symptoms, cognitive dysfunction, and the hallmark symptom, post-exertional malaise. While the cause of this disease remains unknown, there is evidence of a potential infectious component that, along with patient symptoms and common onsets of the disease, implicates immune system dysfunction. To further our understanding of the state of ME/CFS lymphocytes, we characterized the role of fatty acids in isolated Natural Killer cells, CD4+ T cells, and CD8+ T cells in circulation and after overnight stimulation, through implicit perturbations to fatty acid oxidation.

We examined samples obtained from at least 8 and as many as 20 subjects for immune cell fatty acid characterization in a variety of experiments and found that all three isolated cell types increased their utilization of lipids and levels of pertinent proteins involved in this metabolic pathway in ME/CFS samples, particularly during higher energy demands and activation. In T cells, we characterized the cell populations contributing to these metabolic shifts, which included CD4+ memory cells, CD4+ effector cells, CD8+ naïve cells, and CD8+ memory cells.

We also discovered that patients with ME/CFS and healthy control samples had significant correlations between measurements of CD4+ T cell fatty acid metabolism and demographic data. These findings provide support for metabolic dysfunction in ME/CFS immune cells. We further hypothesize about the consequences that these altered fuel dependencies may have on T and NK cell effector function, which may shed light on the illness’s mechanism of action.

Source: Maya J, Leddy SM, Gottschalk CG, Peterson DL, Hanson MR. Altered Fatty Acid Oxidation in Lymphocyte Populations of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Int J Mol Sci. 2023 Jan 19;24(3):2010. doi: 10.3390/ijms24032010. PMID: 36768336; PMCID: PMC9916395. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9916395/ (Full text)

Urine Metabolomics Exposes Anomalous Recovery after Maximal Exertion in Female ME/CFS Patients

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease with unknown etiology or effective treatments. Post-exertional malaise (PEM) is a key symptom that distinguishes ME/CFS patients. Investigating changes in the urine metabolome between ME/CFS patients and healthy subjects following exertion may help us understand PEM.
The aim of this pilot study was to comprehensively characterize the urine metabolomes of eight female healthy sedentary control subjects and ten female ME/CFS patients in response to a maximal cardiopulmonary exercise test (CPET). Each subject provided urine samples at baseline and 24 h post-exercise. A total of 1403 metabolites were detected via LC-MS/MS by Metabolon® including amino acids, carbohydrates, lipids, nucleotides, cofactors and vitamins, xenobiotics, and unknown compounds.
Using a linear mixed effects model, pathway enrichment analysis, topology analysis, and correlations between urine and plasma metabolite levels, significant differences were discovered between controls and ME/CFS patients in many lipid (steroids, acyl carnitines and acyl glycines) and amino acid subpathways (cysteine, methionine, SAM, and taurine; leucine, isoleucine, and valine; polyamine; tryptophan; and urea cycle, arginine and proline).
Our most unanticipated discovery is the lack of changes in the urine metabolome of ME/CFS patients during recovery while significant changes are induced in controls after CPET, potentially demonstrating the lack of adaptation to a severe stress in ME/CFS patients.
Source: Glass KA, Germain A, Huang YV, Hanson MR. Urine Metabolomics Exposes Anomalous Recovery after Maximal Exertion in Female ME/CFS Patients. International Journal of Molecular Sciences. 2023; 24(4):3685. https://doi.org/10.3390/ijms24043685 https://www.mdpi.com/1422-0067/24/4/3685 (Full text available as PDF file)

Multi-‘omics of gut microbiome-host interactions in short- and long-term myalgic encephalomyelitis/chronic fatigue syndrome patients

Highlights

  • Multi-‘omics identified phenotypic, gut microbial, and metabolic biomarkers for ME/CFS.
  • Reduced gut microbial diversity and increased plasma sphingomyelins in ME/CFS.
  • Short-term patients had more severe gut microbial dysbiosis with decreased butyrate.
  • Long-term patients had more significant metabolic and clinical aberrations

Summary

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex, debilitating disorder manifesting as severe fatigue and post-exertional malaise. The etiology of ME/CFS remains elusive.

Here, we present a deep metagenomic analysis of stool combined with plasma metabolomics and clinical phenotyping of two ME/CFS cohorts with short-term (<4 years, n = 75) or long-term disease (>10 years, n = 79) compared with healthy controls (n = 79).

First, we describe microbial and metabolomic dysbiosis in ME/CFS patients. Short-term patients showed significant microbial dysbiosis, while long-term patients had largely resolved microbial dysbiosis but had metabolic and clinical aberrations.

Second, we identified phenotypic, microbial, and metabolic biomarkers specific to patient cohorts. These revealed potential functional mechanisms underlying disease onset and duration, including reduced microbial butyrate biosynthesis and a reduction in plasma butyrate, bile acids, and benzoate.

In addition to the insights derived, our data represent an important resource to facilitate mechanistic hypotheses of host-microbiome interactions in ME/CFS.

Source: Ruoyun Xiong, Courtney Gunter, Elizabeth Fleming, Suzanne D. Vernon, Lucinda Bateman, Derya Unutmaz, Julia Oh. Multi-‘omics of gut microbiome-host interactions in short- and long-term myalgic encephalomyelitis/chronic fatigue syndrome patients. Cell Host & Microbe 31, 273–287. https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(23)00021-5 (Full text)

Studies find that microbiome changes may be a signature for ME/CFS

Researchers have found differences in the gut microbiomes of people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) compared to healthy controls. Findings from two studies, published in Cell Host & Microbe and funded by the National Institutes of Health add to growing evidence that connects disruptions in the gut microbiome, the complete collection of bacteria, viruses, and fungi that live in our gastrointestinal system, to ME/CFS.

“The microbiome has emerged as a potential contributor to ME/CFS. These findings provide unique insights into the role the microbiome plays in the disease and suggest that certain differences in gut microbes could serve as biomarkers for ME/CFS,” said Vicky Whittemore, Ph.D., program director at NIH’s National Institute of Neurological Disorders and Stroke (NINDS).

ME/CFS is a serious, chronic, and debilitating disease characterized by a range of symptoms, including fatigue, post-exertional malaise, sleep disturbance, cognitive difficulties, pain, and gastrointestinal issues. The causes of the disease are unknown and there are no treatments.

In one study, senior author Brent L. Williams, Ph.D., assistant professor, W. Ian Lipkin, M.D., John Snow Professor of Epidemiology and director of the Center for Infection and Immunity at the Columbia University Mailman School of Public Health, in New York City, and their collaborators analyzed the genetic makeup of gut bacteria in fecal samples collected from a geographically diverse cohort of 106 people with ME/CFS and 91 healthy controls. The results revealed key differences in microbiome diversity, quantity, metabolic pathways, and interactions between species of gut bacteria.

Dr. Williams and his colleagues found that people with ME/CFS had abnormally low levels of several bacterial species compared to healthy controls, including Faecalibacterium prausnitzii (F. prausnitzii) and Eubacterium rectale. These health-promoting bacteria produce a short chain fatty acid called butyrate, a bacterial metabolite, or by-product, that plays an important role in maintaining gut health. An acetate-producing bacterium was also reduced in samples obtained from people with ME/CFS.

More detailed metabolomic analyses confirmed that a reduction in these bacteria was associated with reduced butyrate production in ME/CFS. Butyrate is the primary energy source for cells that line the gut, providing up to 70% of their energy requirements, support for the gut immune system, and protection against diseases of the digestive tract. Butyrate, tryptophan, and other metabolites detected in the blood are important for regulating immune, metabolic, and endocrine functions.

While species of butyrate-producing bacteria decreased, there were increased levels of nine other species in ME/CFS, including Enterocloster bolteae and Ruminococcus gnavus, which are associated with autoimmune diseases and inflammatory bowel disease, respectively.

Dr. Williams’ group also reported that an abundance of F. prausnitzii was inversely associated with fatigue severity in ME/CFS, suggesting a possible link between gut bacteria and disease symptoms. More research is needed to determine if differences in the gut microbiome are a consequence or cause of symptoms.

The findings indicate that imbalances in these 12 species of bacteria could be used as biomarkers for ME/CFS classification, potentially providing consistent, measurable targets to improve diagnosis.

The gut microbiome is an ecosystem with complex interactions between bacteria, where microbes can exchange or compete for nutrients, metabolites, or other molecular signals. Researchers found notable differences in the network of species interactions in people with ME/CFS—including unique interactions between F. prausnitzii and other species. This indicates that there is an extensive rewiring of bacterial networks in ME/CFS.

“In addition to differences in individual species in ME/CFS, focusing a lens on community interaction dynamics may add greater specificity to the broad definition of dysbiosis, distinguishing between other diseases in which the gut microbiome becomes imbalanced,” said Dr. Williams. “This is also important for generating new testable hypotheses about the underlying mechanisms and mediators of dysbiosis in ME/CFS and may eventually inform strategies to correct these imbalances.”

A balanced microbiome is also essential for a variety of neural systems, especially immune regulation and coupling between energy metabolism and blood supply in the brain, as well as the function of the nerves that supply the gut.

In another study at the Jackson Laboratory in Farmington, Connecticut, Julia Oh, Ph.D.(link is external), associate professor, and Derya Unutmaz, M.D., professor, teamed up with other ME/CFS experts to study microbiome abnormalities in different phases of ME/CFS. Dr. Oh’s team collected and analyzed clinical data, fecal samples, and blood samples from 149 people with ME/CFS who had been diagnosed within the previous four years (74 short-term) or who had been diagnosed more than 10 years ago (75 long-term) and 79 healthy controls.

The results showed that the short-term group had less microbial diversity, while the long-term group established a stable, but individualized gut microbiome similar to healthy controls. Dr. Oh and her colleagues found lower levels of several butyrate-producing species, including F. prausnitzii, especially in the short-term participants. There was also a reduction in species associated with tryptophan metabolism in all ME/CFS participants compared to controls.

Dr. Oh’s group also collected detailed clinical and lifestyle data from participants. By combining these data with genetic and metabolome data, the team developed a way to accurately classify and differentiate ME/CFS from healthy controls. Using this approach, they found that individuals with long-term ME/CFS had a more balanced microbiome but showed more severe clinical symptoms and progressive metabolic irregularities compared to the other groups.

Both studies identify potential biomarkers for ME/CFS, which may inform diagnostic tests and disease classification. Understanding the connection between disturbances in the gut microbiome and ME/CFS may also guide the development of new therapeutics.

Additional research is required to learn more about the pathophysiological implications of butyrate and other metabolite deficiencies in ME/CFS. Future studies will determine how gut microbe disturbances contribute to symptoms, including changes during disease progression.

The studies were funded in part by the NIH’s ME/CFS Collaborative Research Network(link is external), a consortium supported by multiple institutes and centers at NIH, consisting of three collaborative research centers and a data management coordinating center. The research network was established in 2017 to help advance research on ME/CFS. The research was supported by NINDS grant U54NS105539, National Institute of Allergy and Infectious Diseases grants U54AI138370 and R56AI120724, and anonymous donors through the Crowdfunding Microbe Discovery Project.