Category: Immune System

Increasing serum soluble CD40 ligand (sCD40L) may be a biomarker of ME/CFS and chronic Long COVID progression

Abstract:

To date, no single blood lab test exists to diagnose or track ME/CFS or chronic Long COVID. Based on existing literature, this article brings together evidence that a molecule secreted by the immune system called sCD40L tends to become increasingly elevated in ME/CFS, Long COVID, and Multiple Sclerosis.

These studies, along with what’s known about the role of sCD40L in health and other diseases, suggest sCD40L may be useful to track over time in ME/CFS and Long COVID patients.

Source: Vijay Iyer. Increasing serum soluble CD40 ligand (sCD40L) may be a biomarker of ME/CFS and chronic Long COVID progression. Patient-Generated Hypotheses Journal | Issue 1, May 2023. https://patientresearchcovid19.com/storage/2023/05/Patient-Generated-Hypotheses-Issue-1-May-2023.pdf#page=42 (Full text)

Inflammation-induced pain and fatigue in fibromyalgia and ME/CFS and role of variant connective tissue

Abstract:

Background: Fibromyalgia and ME/CFS are multifaceted conditions with overlapping symptoms(1); the pathophysiological mechanisms are under debate. It remains unclear whether dysregulated inflammation, induced either by an exogenous stimulus (eg a virus or other stressor), or autoimmunity, is of prime importance [2].

Objectives: 1. To determine in a novel human model the effects of an in vivo inflammatory challenge in the induction of pain and fatigue in fibromyalgia and ME/CFS compared to controls. 2. Explore potential mediators and moderators involved.

Methods: Data were available for 48 patients with confirmed diagnoses of Fibromyalgia and/ or ME/CFS and 22 matched controls, who had undergone a placebo controlled inflammatory challenge (typhoid vaccination) as part of ISRCTN78820481. Participants underwent full research diagnostic evaluation including a hypermobility assessment. Subjective pain and fatigue were assessed after saline injection and typhoid vaccination (VAS). Linear regression models were used to explore predictors, with adjustment for potential confounders (age/gender) and baseline levels as appropriate.

Mediation analyses (looking for mechanistic effects) were conducted according to the method of Hayes (3) and mediation considered significant if bootstrapped confidence intervals of the estimated indirect effect did not cross zero. In these mediation analyses predictor variable was group membership (patient or control), outcome variable was change in 1) pain and 2) fatigue induced by challenge and mediators/moderators included change in IL-6 induced by inflammatory challenge and hypermobility features.

Results: Being a patient rather than control significantly predicted inflammation-induced fatigue (B=14.89 (95%CI 3.29-26.50), t=2.56, p=0.013) and pain (B=12.88 (95%CI 0.65-25.10), t=2.11, p=0.039) after adjusting for levels induced by placebo.

Induced pain was independently predicted by level of IL-6 induced by inflammatory challenge (B=23.44 (95%CI 5.15-41.72),t=2.57, p=0.013) as was induced fatigue (B=10.63 (95%CI 2.84-18.41), t=2.73, p=0.008) Mediated moderation analyses suggested the link to induced pain and fatigue through induced inflammation was associated with hypermobility features (Index of mediated moderation 11.02 (95%CI 1.45-22.73) and 6.20 (95%CI 0.07-13.64) respectively))

Conclusion: To our knowledge this is the first human study to evaluate directly the effect of an exogenous inflammatory challenge (typhoid vaccination) in a combined group of Fibromyalgia and ME/CFS patients. Il-6 was shown to be a critical mediator. This work strongly supports the hypothesis that inflammation is key to the pathophysiology of ME/CFS. We are evaluating associated CNS inflammation in the model, as well as other associations, such as autonomic dysfunction and hypermobility. Further understanding the mediators involved in the condition should in future open the way to testing targeted anti-inflammatory therapy.

Source: Eccles J, Amato M, Themelis K, et alOP0194 INFLAMMATION-INDUCED PAIN AND FATIGUE IN FIBROMYALGIA AND ME/CFS AND ROLE OF VARIANT CONNECTIVE TISSUEAnnals of the Rheumatic Diseases 2023;82:129. https://ard.bmj.com/content/82/Suppl_1/129.2 (Full text)

Investigating antibody reactivity to the intestinal microbiome in severe myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multisystemic disease of unknown aetiology that is characterised by disabling chronic fatigue and involves both the immune and gastrointestinal (GI) systems. Patients display alterations in GI microbiome with a significant proportion experiencing GI discomfort and pain and elevated blood biomarkers for altered intestinal permeability compared with healthy individuals.

To investigate a possible GI origin of ME/CFS we designed a feasibility study to test the hypothesis that ME/CFS pathogenesis is a consequence of increased intestinal permeability that results in microbial translocation and a breakdown in immune tolerance leading to generation of antibodies reactive to indigenous intestinal microbes. Secretory IgA and serum IgG levels and reactivity to intestinal microbes were assessed in five pairs of severe ME/CFS patients and matched same-household healthy controls. For profiling serum IgG we developed IgG-Seq which combines flow-cytometry based bacterial cell sorting and metagenomics to detect mucosal IgG reactivity to the microbiome.

We uncovered evidence for immune dysfunction in severe ME/CFS patients that was characterised by reduced capacity and reactivity of serum IgG to stool microbes, irrespective of their source. This study provides the rationale for additional studies in larger cohorts of ME/CFS patients to further explore immune-microbiome interactions.

Source: Katharine A. Seton, Marianne Defernez, Andrea Telatin, Sumeet K. Tiwari, George M. Savva, Antonietta Hayhoe, Alistair Noble, Ana Carvalho, Steve James, Amolak Bansal, Thomas Wileman, Simon R. Carding. Investigating antibody reactivity to the intestinal microbiome in severe myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). medRxiv 2023.05.21.23290299; doi: https://doi.org/10.1101/2023.05.21.23290299 https://www.medrxiv.org/content/10.1101/2023.05.21.23290299v1.full-text (Full text)

Free-water-corrected diffusion and adrenergic/muscarinic antibodies in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Background and purpose: Free-water-corrected diffusion tensor imaging (FW-DTI), a new analysis method for diffusion MRI, can indicate neuroinflammation and degeneration. There is increasing evidence of autoimmune etiology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). We used FW-DTI and conventional DTI to investigate microstructural brain changes related to autoantibody titers in patients with ME/CFS.

Methods: We prospectively examined 58 consecutive right-handed ME/CFS patients who underwent both brain MRI including FW-DTI and a blood analysis of autoantibody titers against β1 adrenergic receptor (β1 AdR-Ab), β2 AdR-Ab, M3 acetylcholine receptor (M3 AchR-Ab), and M4 AchR-Ab. We investigated the correlations between these four autoantibody titers and three FW-DTI indices-free water (FW), FW-corrected fractional anisotropy (FAt), and FW-corrected mean diffusivity-as well as two conventional DTI indices-fractional anisotropy (FA) and mean diffusivity. The patients’ age and gender were considered as nuisance covariates. We also evaluated the correlations between the FW-DTI indices and the performance status and disease duration.

Results: Significant negative correlations between the serum levels of several autoantibody titers and DTI indices were identified, mainly in the right frontal operculum. The disease duration showed significant negative correlations with both FAt and FA in the right frontal operculum. The changes in the FW-corrected DTI indices were observed over a wider extent compared to the conventional DTI indices.

Conclusions: These results demonstrate the value of using DTI to assess the microstructure of ME/CFS. The abnormalities of right frontal operculum may be a diagnostic marker for ME/CFS.

Source: Kimura Y, Sato W, Maikusa N, Ota M, Shigemoto Y, Chiba E, Arizono E, Maki H, Shin I, Amano K, Matsuda H, Yamamura T, Sato N. Free-water-corrected diffusion and adrenergic/muscarinic antibodies in myalgic encephalomyelitis/chronic fatigue syndrome. J Neuroimaging. 2023 May 27. doi: 10.1111/jon.13128. Epub ahead of print. PMID: 37243973. https://pubmed.ncbi.nlm.nih.gov/37243973/

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)

Achieving symptom relief in patients with Myalgic encephalomyelitis by targeting the neuro-immune interface and optimizing disease tolerance

Abstract:

Myalgic encephalomyelitis, ME, previously also known as chronic fatigue syndrome (CFS) is a heterogeneous, debilitating syndrome of unknown etiology responsible for long-lasting disability in millions of patients worldwide. The most well-known symptom of ME is post-exertional malaise, but many patients also experience autonomic dysregulation, cranial nerve dysfunction and signs of immune system activation. Many patients also report a sudden onset of disease following an infection.

The brainstem is a suspected focal point in ME pathogenesis and patients with structural impairment to the brainstem often show ME-like symptoms. The brainstem is also where the vagus nerve originates, a critical neuro-immune interface and mediator of the inflammatory reflex which regulate systemic inflammation.

Here we report the results of a randomized, placebo-controlled trial using intranasal mechanical stimulation (INMEST) targeting nerve endings in the nasal cavity, likely from the trigeminal nerve, possibly activating additional centers in the brainstem of ME-patients and correlating with a ∼30% reduction in overall symptom scores after eight weeks of treatment.

By performing longitudinal, systems-level monitoring of the blood immune system in these patients, we uncover signs of chronic immune activation in ME, as well as immunological correlates of improvement that center around gut-homing immune cells and reduced inflammation.

The mechanisms of symptom relief remains to be determined, but transcriptional analyses suggest an upregulation of disease tolerance mechanisms. We believe that these results are suggestive of ME as a condition explained by a maladaptive disease tolerance response following infection.

Source: Lucie Rodriguez, Christian Pou, Tadepally Lakshmikanth, Jingdian Zhang, Constantin Habimana Mugabo, Jun Wang, Jaromir Mikes, Axel Olin, Yang Chen, Joanna Rorbach, Jan-Erik Juto, Tie Qiang Li, Per Julin, Petter Brodin, Achieving symptom relief in patients with Myalgic encephalomyelitis by targeting the neuro-immune interface and optimizing disease tolerance, Oxford Open Immunology, 2023;, iqad003, https://doi.org/10.1093/oxfimm/iqad003 (Full text available as PDF file)

A review of cytokine-based pathophysiology of Long COVID symptoms

Abstract:

The Long COVID/Post Acute Sequelae of COVID-19 (PASC) group includes patients with initial mild-to-moderate symptoms during the acute phase of the illness, in whom recovery is prolonged, or new symptoms are developed over months. Here, we propose a description of the pathophysiology of the Long COVID presentation based on inflammatory cytokine cascades and the p38 MAP kinase signaling pathways that regulate cytokine production.

In this model, the SARS-CoV-2 viral infection is hypothesized to trigger a dysregulated peripheral immune system activation with subsequent cytokine release. Chronic low-grade inflammation leads to dysregulated brain microglia with an exaggerated release of central cytokines, producing neuroinflammation. Immunothrombosis linked to chronic inflammation with microclot formation leads to decreased tissue perfusion and ischemia. Intermittent fatigue, Post Exertional Malaise (PEM), CNS symptoms with “brain fog,” arthralgias, paresthesias, dysautonomia, and GI and ophthalmic problems can consequently arise as result of the elevated peripheral and central cytokines.

There are abundant similarities between symptoms in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). DNA polymorphisms and viral-induced epigenetic changes to cytokine gene expression may lead to chronic inflammation in Long COVID patients, predisposing some to develop autoimmunity, which may be the gateway to ME/CFS.

Source: Low RN, Low RJ, Akrami A. A review of cytokine-based pathophysiology of Long COVID symptoms. Front Med (Lausanne). 2023 Mar 31;10:1011936. doi: 10.3389/fmed.2023.1011936. PMID: 37064029; PMCID: PMC10103649. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10103649/ (Full text)

Natural killer cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a multi-site clinical assessment of ME/CFS (MCAM) sub-study

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a multisystem illness characterized by substantial reduction in function accompanied by profound unexplained fatigue not significantly relieved by rest, post-exertional malaise, and other symptoms. Reduced natural killer (NK) cell count and cytotoxicity has been investigated as a biomarker for ME/CFS, but few clinical laboratories offer the test and multi-site verification studies have not been conducted.

Methods: We determined NK cell counts and cytotoxicity in 174 (65%) ME/CFS, 86 (32%) healthy control (HC) and 10 (3.7%) participants with other fatigue associated conditions (ill control [IC]) from the Multi-Site Clinical Assessment of ME/CFS (MCAM) study using an assay validated for samples shipped overnight instead of testing on day of venipuncture.

Results: We found a large variation in percent cytotoxicity [mean and (IQR) for ME/CFS and HC respectively, 34.1% (IQR 22.4-44.3%) and 33.6% (IQR 22.9-43.7%)] and no statistically significant differences between patients with ME/CFS and HC (p-value = 0.79). Analysis stratified on illness domain measured with standardized questionnaires did not identify an association of NK cytotoxicity with domain scores. Among all participants, NK cytotoxicity was not associated with survey results of physical and mental well-being, or health factors such as history of infection, obesity, smoking, and co-morbid conditions.

Conclusion: These results indicate this assay is not ready for clinical implementation and studies are needed to further explore immune parameters that may be involved in the pathophysiology of ME/CFS.

Source: Querec TD, Lin JS, Chen Y, Helton B, Kogelnik AM, Klimas NG, Peterson DL, Bateman L, Lapp C, Podell RN, Natelson BH, Unger ER; MCAM Study Group. Natural killer cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a multi-site clinical assessment of ME/CFS (MCAM) sub-study. J Transl Med. 2023 Apr 3;21(1):242. doi: 10.1186/s12967-023-03958-2. PMID: 37013608. https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-023-03958-2 (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)

Investigating the Genetic and Immunological Aetiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

This thesis describes two investigations into the disease Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), specifically its genetic aetiology and immune system alterations.

The first study investigated the genetic basis of ME/CFS using Genome-wide Association Studies (GWAS) by attempting to replicate and extend results previously found using UK Biobank cohort data. GWAS attempt to identify associations between DNA variants and phenotypes. T his GWAS was novel, conducted on new phenotypes constructed by combining those in the most up-to-date UK Biobank data release. A new, previously unseen, genome-wide significant association was found on chromosome 6 for males with ME/CFS within the gene PDE10A. Further results were not genome-wide significant, but many were suggestive and hence independent replication may justify further research.

A previous analysis on the UK Biobank cohort had identified an indicative association in females between variants around the SLC25A15 gene at genome-wide significance. I adopted a hypothesis that the dietary protein intake of people with the CFS risk variants would be lower than those with the alternative alleles, due to potentially reduced production of mitochondrial ornithine transporter 1 (ORNT1). However, this association with dietary protein intake was not supported by UK Biobank data.

Additionally, I investigated associations between the human leukocyte antigen (HLA) alleles and the ME/CFS phenotype using UK Biobank data. Associations between alleles within the HLA-C and -DQB1 genes had previously been found in a cohort of Norwegian people with ME/CFS, and my goal was to seek replication of these results in a larger dataset. None of the associations found in the UK Biobank proved to be genome-wide significant.

In my second study I investigated the use of T-cell clonal diversity as a potential biomarker for ME/CFS. This project used cells from CureME Biobank samples in collaboration with Systems Biology Laboratory (SBL). I developed a data analysis pipeline to analyse T-cell receptor (TCR) genomic DNA data based on the best practices currently used in the fields of immunology and mathematical biology. This approach used a mathematical notion of entropy as a measure for the diversity of TCR repertoires, in this way combining all of the most commonly used metrics in mathematical biology. When combined, these measures form a profile for each repertoire, a set of which can be sorted using a machine learning algorithm to partition the repertoires into subgroups.

My hypothesis was that the T-cell clonal expansion of people with ME/CFS would be greater than for healthy controls, and comparable to disease (multiple sclerosis) controls. Although this method was able to effectively classify TCR chains using simulated data, results from experimentally-derived data did not support the hypothesis, with the most effective classifications for both CD4+ and CD8+ cells failing to pass corrections for multiple hypothesis significance testing.

Lay summary

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disease that affects millions of people around the world. Very little is understood about the cause or progression of the disease, and there is no known cure. At present, there is also no reliable clinical test to determine whether a person has ME/CFS.

This thesis explores the potential for a genetic or immunological basis for ME/CFS, with the goal to eventually find a biomarker that could be used in diagnosis.

The first part of this thesis investigates whether genetic variants are more (or less) common among those with ME/CFS than in the general population. In particular, the region of the genome that encodes immune system proteins was of interest, as previous studies have shown associations between this region and the disease.

Using strict statistical thresholds, none of the previously found associations were replicated. However, one new association was found, with the gene PDE10A, which is implicated in central nervous system diseases, such as Parkinsons and Huntingtons disease. This association has never been seen before, and would require replication in a new cohort before its role in ME/CFS could be confirmed. However, it represents a promising avenue for new research.

The second part of this thesis investigates T-cells. These are highly specialised immune cells in the blood, each of which targets an antigen (foreign substance) such as from a virus. When a T-cell recognises this antigen, it clones itself repeatedly. This clonal expansion is measurable, and can serve as evidence of immune system activation.

My hypothesis was that this immune signature could be used to distinguish people with ME/CFS from healthy controls and others diagnosed with another disease.

I used a mathematical measure of diversity and a machine learning method to sort their immune profiles into groups. However, the pattern of immune activation was not sufficiently clear to provide consistent classification. Hence, the role of the immune system in ME/CFS is still unclear, and the utility of this method as a diagnostic biomarker is not proved.

Source: Joshua James Dibble. Investigating the Genetic and Immunological Aetiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. PhD Thesis [University of Edinburgh]  https://era.ed.ac.uk/bitstream/handle/1842/39763/DibbleJJ_2022.pdf?sequence=1&isAllowed=y (Full text)