Category: Etiology

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)

What Causes ME/CFS: The Role of the Dysfunctional Immune System and Viral Infections

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) remains an enigmatic highly disabling and complex long-term condition with a wide range of aetiologies and symptoms.

A viral onset is commonly mentioned by patients and several bodily systems are ultimately disturbed. The parallel with long-covid is clear.

However, immune dysregulation with impaired NK cell dysfunction and tendency to novel autoimmunity have been frequently reported. These may contribute to reactivation of previous acquired viruses/retroviruses accompanied by impaired endocrine regulation and mitochondrial energy generation.

The unpredictable nature of seemingly unconnected and diverse symptoms that are poorly responsive to several allopathic and alternative therapies then contributes to an escalation of the illness with secondary dysfunction of multiple other systems. Treatment of established ME/CFS is therefore difficult and requires multi-specialty input addressing each of the areas affected by the illness.

Source: Amolak S Bansal, Aletta D Kraneveld, Elisa Oltra and Simon Carding. What Causes ME/CFS: The Role of the Dysfunctional Immune System and Viral Infections. Journal of Immunology and Allergy 2022;3(2):1-15. https://maplespub.co.in/assets/images/files/doc_1663924267.pdf (Full text)

Investigating the enterovirus theory of disease etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multi-system disease whose etiological basis has not been established. Over the years, several pathogenic agents have been implicated with no one pathogen being conclusively identified as responsible for induction of a large number of cases. Enteroviruses (EVs) as a cause of ME/CFS have sometimes been proposed, as they are known agents of acute respiratory and gastrointestinal infections that may persist in chronic infection sites, including the central nervous system, muscle, and heart, potentially resulting in chronic conditions that have symptom constellations like those of ME/CFS.

To gain insight into the association between EVs and ME/CFS, I conducted a comprehensive review of EV studies in ME/CFS and followed this with 1) a broad serological survey of ME/CFS antibody levels to 122 pathogenic antigens and 2) designed and conducted EV-specific targeted RNA sequencing.

A review of prior ME/CFS investigations in ME/CFS revealed a strong prevalence of chronic EV infections across ME/CFS cohorts. The broad survey of anti-pathogen antibody levels in ME/CFS cases did not implicate any one pathogen as a causative factor in ME/CFS, nor do they rule out common pathogens that frequently infect the US population. However, the results did reveal sex-based differences in steady-state humoral immunity, both within the ME/CFS cohort and when compared to trends seen in the healthy control cohort.

Furthermore, I find that our EV-specific probe set allows efficient viral detection when as few as 10 molecules are present in 1ml of blood. However, whether the technology is employed directly on patient samples or following attempts at in vitro biological amplification, EVs were undetected in both ME/CFS and healthy control samples despite all approaches that were pursued.

This work establishes a thorough understanding of the current EV-ME/CFS related literature while simultaneously providing an acutely sensitive and comprehensive approach that will be useful in the future for screening biopsy or cadaver samples from any individuals suspected of having a chronic EV infection.

Source: O’Neal, Adam James. Investigating the enterovirus theory of disease etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Dissertation, Cornell. https://ecommons.cornell.edu/handle/1813/112023 (Full text will be made available)

COVID-19 May Be a Trigger for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

ALBANY, N.Y. (July 25, 2022) – UAlbany researcher Roxana Moslehi from the Department of Epidemiology and Biostatistics is conducting important investigations on myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to better understand the illness, including its potential connection to cancer, auto-immune disease, and long-haul COVID-19.

According to the CDC, 1 in thirteen adults in the U.S. have COVID-19 symptoms lasting three or more months after contracting the virus—a condition often referred to as “long COVID.” However, research suggests that long COVID is complex, and in some instances may not be COVID-19 at all, but rather ME/CFS—triggered by COVID-19.

ME/CFS is a complex disabling disorder with no known treatment. Between 25 and 50 percent of those with the illness are bed or housebound for extended periods of time, with overwhelming fatigue that does not diminish after resting and difficulty performing daily tasks. Prior to the COVID-19 pandemic, it was estimated that up to 3.4 million people in the US suffered from the illness—the range is large due to the difficulty in diagnosing the disease as it is often dismissed or assumed to be another disorder.

Since ME/CFS is believed to be triggered by the onset of an infectious illness, research suggests that COVID-19 may be a trigger for ME/CFS. The chronic long-haul COVID-19 symptoms that some people report as following the resolution of their acute illness have similarities to symptoms of ME/CFS, such as persistent fatigue, sleep dysfunction, cognitive impairment, impaired memory, and more.

“It is estimated that in the wake of the COVID-19 pandemic, more than 10 million new ME/CFS cases may be triggered around the world,” Moslehi explains. “This makes it urgent to identify risk factors and underlying biologic mechanisms for this condition along with its potential connection to COVID-19.”

Moslehi conducted a molecular epidemiologic investigation of ME/CFS (funded by an NIH research grant awarded to her) to better understand the illness, providing the most compelling evidence to date that ME/CFS may be an auto-immune disorder. She compared people who developed ME/CFS after having an infectious illness with a group of individuals without ME/CFS (called the control group). She looked at various intrinsic factors related to the participants’ health, such as personal history of allergy and asthma, and extrinsic or environmental factors such as exposure to contaminants. She also assessed the prevalence of illnesses such as auto-immune diseases and cancer in their families, levels of serum immune system markers such as cytokines, and molecular evidence of viral reactivation such as mono flare-ups.

The study, published in the proceedings of the American Society of Human Genetics (ASHG), the International Genetic Epidemiology Society (IGES) and the American Association for Cancer Research (AACR), found that those with ME/CFS were five times more likely to have a family history of auto-immune diseases than the control group. ME/CFS was also associated with an increased risk of early-onset cancer (diagnosed before 60 years old) among the first-degree relatives. ME/CFS was associated with certain risk factors such as a history of allergies requiring medication and exposure to contaminants. The analysis by the Moslehi lab also identified a panel of cytokines that predict the risk of ME/CFS with high accuracy. A couple of the identified cytokines are involved in inflammatory processes and have been linked to other auto-immune diseases.

“Our multidimensional analysis of pedigree, epidemiologic, and molecular data not only provides the most objective evidence to date that ME/CFS may be an auto-immune disease— it provides etiologic clues and leads for prevention” says Moslehi. “In addition, our results may enable defining a subset of COVID-19 patients, who are at risk of developing long COVID or ME/CFS, for targeted monitoring and/or therapy.”

More recently, Moslehi, in collaboration with her colleagues at the NIH, obtained two additional NIH (intramural) grants to continue her research on ME/CFS. Through these grants, the DNA and RNA of ME/CFS cases and controls have been sequenced and will be analyzed to identify genes and genetic variations that are associated with ME/CFS.

“The ultimate goal is to conduct an integrative analysis of multi-omics (genomics, proteomics, transcriptomics) data to gain deeper insight into the biologic mechanisms of ME/CFS and identify druggable targets for ME/CFS therapy,” she says.

 

Evidence for active Epstein-Barr virus infection in patients with persistent, unexplained illnesses: elevated anti-early antigen antibodies

Abstract:

Forty-four patients, including 26 adults and 18 children under 15 years of age, were referred for evaluation of recurrent or persistent illnesses, with symptoms including pharyngitis, lymphadenopathy, fever, headaches, arthralgia, fatigue, depression, dyslogia, and myalgia. Thirty-nine patients were positive for Epstein-Barr virus antibody with antibody levels compatible with active infection for at least 1 year. Antiviral capsid antigen and anti-early antigen titers of patients were significantly greater (p less than 0.001) than age-group-matched controls. The frequency, number, duration, and patterns of symptoms, as well as patient sex, were compared by age in study patients seropositive and seronegative for Epstein-Barr virus. Illness patterns were not associated with changes in specific antibody titers or clinical findings. Lymphocyte phenotype and function analyses were done in 11 of the 39 patients positive for Epstein-Barr virus antibody; no consistent differences from normal were found. Only 1 of 32 patients had circulating interferon, in contrast to 7 of 7 patients with acute infectious mononucleosis. There were many adverse consequences of the illness. Epstein-Barr virus infection may not be self-limiting, and the virus may be associated with clinically recognizable illness other than infectious mononucleosis in children as well as in adults.

Source:Jones JF, Ray CG, Minnich LL, Hicks MJ, Kibler R, Lucas DO. Evidence for active Epstein-Barr virus infection in patients with persistent, unexplained illnesses: elevated anti-early antigen antibodies. Ann Intern Med. 1985 Jan;102(1):1-7. doi: 10.7326/0003-4819-102-1-. PMID: 2578266. https://pubmed.ncbi.nlm.nih.gov/2578266/

Chronic Fatigue Exhibits Heterogeneous Autoimmunity Characteristics Which Reflect Etiology

Abstract:

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is considered to be associated with post-viral complications and mental stress, but the role of autoimmunity also remains promising. A comparison of autoimmune profiles in chronic fatigue of different origin may bring insights on the pathogenesis of this disease.

Thirty-three patients with CFS/ME were divided into three subgroups. The first group included Herpesviridae carriers (group V), the second group included stress-related causes of chronic fatigue (distress, group D), and the third group included idiopathic CFS/ME (group I). Were evaluated thirty-six neural and visceral autoantigens with the ELISA ELI-test (Biomarker, Russia) and compared to 20 healthy donors, either without any fatigue (group H), or “healthy but tired” (group HTd) with episodes of fatigue related to job burnout not fitting the CFS/ME criteria.

β2-glycoprotein-I autoantibodies were increased in CFS/ME patients, but not in healthy participants, that alludes the link between CFS/ME and antiphospholipid syndrome (APS) earlier suspected by Berg et al. (1999). In CFS/ME patients, an increase in levels of autoantibodies towards the non-specific components of tissue debris (double-stranded DNA, collagen) was shown. Both CFS and HTd subgroups had elevated level of autoantibodies against serotonin receptors, glial fibrillary acidic protein and protein S100. Only group V showed an elevation in the autoantibodies towards voltage-gated calcium channels, and only group D had elevated levels of dopamine-, glutamate- and GABA-receptor autoantibodies, as well as NF200-protein autoantibodies.

Therefore, increased autoimmune reactions to the multiple neural antigens and to adrenal medullar antigen, but not to other tissue-specific somatic ones were revealed. An increase in autoantibody levels towards some neural and non-tissue-specific antigens strongly correlated with a CFS/ME diagnosis. Autoimmune reactions were described in all subtypes of the clinically significant chronic fatigue. Visceral complaints in CFS/ME patients may be secondary to the neuroendocrine involvement and autoimmune dysautonomia. CFS may be closely interrelated with antiphospholipid syndrome, that requires further study.

Source: Danilenko OV, Gavrilova NY, Churilov LP. Chronic Fatigue Exhibits Heterogeneous Autoimmunity Characteristics Which Reflect Etiology. Pathophysiology. 2022 May 25;29(2):187-199. doi: 10.3390/pathophysiology29020016. PMID: 35736644.  https://www.mdpi.com/1873-149X/29/2/16/htm (Full text)

Survey of Anti-Pathogen Antibody Levels in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Infectious pathogens are implicated in the etiology of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) because of the occurrence of outbreaks of the disease. While a number of different infectious agents have been associated with the onset of ME/CFS, the identity of a specific organism has been difficult to determine in individual cases. The aim of our study is to survey ME/CFS subjects for evidence of an infectious trigger and/or evidence of immune dysregulation via serological testing of plasma samples for antibodies to 122 different pathogen antigens.
Immune profiles were compared to age-, sex-, and BMI-matched controls to provide a basis for comparison. Antibody levels to individual antigens surveyed in this study do not implicate any one of the pathogens in ME/CFS, nor do they rule out common pathogens that frequently infect the US population. However, our results revealed sex-based differences in steady-state humoral immunity, both within the ME/CFS cohort and when compared to trends seen in the healthy control cohort.
Source: O’Neal AJ, Glass KA, Emig CJ, Vitug AA, Henry SJ, Shungu DC, Mao X, Levine SM, Hanson MR. Survey of Anti-Pathogen Antibody Levels in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Proteomes. 2022; 10(2):21. https://doi.org/10.3390/proteomes10020021 https://www.mdpi.com/2227-7382/10/2/21/htm (Full text)

Unexplained post-acute infection syndromes

Abstract:

SARS-CoV-2 is not unique in its ability to cause post-acute sequelae; certain acute infections have long been associated with an unexplained chronic disability in a minority of patients. These post-acute infection syndromes (PAISs) represent a substantial healthcare burden, but there is a lack of understanding of the underlying mechanisms, representing a significant blind spot in the field of medicine.

The relatively similar symptom profiles of individual PAISs, irrespective of the infectious agent, as well as the overlap of clinical features with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), suggest the potential involvement of a common etiopathogenesis.

In this Review, we summarize what is known about unexplained PAISs, provide context for post-acute sequelae of SARS-CoV-2 infection (PASC), and delineate the need for basic biomedical research into the underlying mechanisms behind this group of enigmatic chronic illnesses.

Source: Choutka J, Jansari V, Hornig M, Iwasaki A. Unexplained post-acute infection syndromes. Nat Med. 2022 May;28(5):911-923. doi: 10.1038/s41591-022-01810-6. Epub 2022 May 18. PMID: 35585196. https://www.nature.com/articles/s41591-022-01810-6 (Full text)

Perspective: Drawing on Findings From Critical Illness to Explain Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

We propose an initial explanation for how myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) could originate and perpetuate by drawing on findings from critical illness research. Specifically, we combine emerging findings regarding (a) hypoperfusion and endotheliopathy, and (b) intestinal injury in these illnesses with our previously published hypothesis about the role of (c) pituitary suppression, and (d) low thyroid hormone function associated with redox imbalance in ME/CFS.

Moreover, we describe interlinkages between these pathophysiological mechanisms as well as “vicious cycles” involving cytokines and inflammation that may contribute to explain the chronic nature of these illnesses. This paper summarizes and expands on our previous publications about the relevance of findings from critical illness for ME/CFS. New knowledge on diagnostics, prognostics and treatment strategies could be gained through active collaboration between critical illness and ME/CFS researchers, which could lead to improved outcomes for both conditions.

Source: Stanculescu Dominic, Bergquist Jonas. Perspective: Drawing on Findings From Critical Illness to Explain Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Frontiers in Medicine, 9, 2022. DOI: 10.3389/fmed.2022.818728 https://www.frontiersin.org/articles/10.3389/fmed.2022.818728/full#h1 (Full text)

Predictors for Developing Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome following Infectious Mononucleosis

Abstract:

Background: About 10% of individuals who contract infectious mononucleosis (IM) have symptoms 6 months later that meet criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).  Our study for the first time examined whether it is possible to predict who will develop ME/CFS following IM.

Methods: We have reported on a prospectively recruited cohort of 4,501 college students, of which 238 (5.3%) developed IM.  Those who developed IM were followed-up at six months to determine whether they recovered or met criteria for ME/CFS. The present study focuses on 48 students who after six months had a diagnosis of ME/CFS, and a matched control group of 58 students who had no further symptoms after their IM. All of these 106 students  had data at baseline (at least 6 weeks prior to the development of IM), when experiencing IM, and 6 months following IM. Of those who did not recover from IM, there were two groups: 30 were classified as ME/CFS and 18 were classified as severe ME/CFS. We measured the results of 7 questionnaires, physical examination findings, the severity of mononucleosis and cytokine analyses at baseline (pre-illness) and at the time of IM.  We examined predictors (e.g., pre-illness variables as well as variables at onset of IM) of  those who developed ME/CFS and severe ME/CFS following IM.

Results: From analyses using receiver operating characteristic statistics, the students who had had severe gastrointestinal symptoms of stomach pain, bloating, and an irritable bowel at baseline  and who also had abnormally low levels of the immune markers IL-13 and/or IL-5 at baseline, as well as severe gastrointestinal symptoms when then contracted IM,  were found to have a nearly 80% chance of having severe ME/CFS persisting six months following IM.

Conclusions: Our findings are consistent with emerging literature that gastrointestinal distress and autonomic symptoms, along with several immune markers, may be implicated in the development of severe ME/CFS.

Source: Jason, Leonard & Cotler, Joseph & Islam, Mohammed & Furst, Jacob & Katz, Ben. (2022). Predictors for Developing Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome following Infectious Mononucleosis. Journal of Rehabilitation Therapy. 4. 1-5. 10.29245/2767-5122/2021/1.1129. https://www.rehabiljournal.com/articles/predictors-for-developing-severe-myalgic-encephalomyelitischronic-fatigue-syndrome-following-infectious-mononucleosis.html  (Full text)