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Subgrouping Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Linking the Powerhouses of Cells to the Autonomic Nervous System (MITAP)

4 november 2026 uppdaterad av: Jente Van Campenhout, Vrije Universiteit Brussel

Mitochondrial Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Are Autonomic Phenotypes Necessary to Clear Conflicting Results?

The goal of this study is to investigate whether mitochondrial dysfunction is present in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) by subgrouping them into autonomic phenotypes. The main questions it aims to answer are:

  • When patients with ME/CFS are exposed to situations stressing the mitochondria and autonomic nervous system, is the response of their mitochondria and autonomic nervous system dependent on to which autonomic profile the patients belong?
  • Is the presence of mitochondrial dysfunction dependent on to which autonomic profile a patient with ME/CFS belongs? Researchers will compare healthy control subjects because very little is known about the link between mitochondria and the autonomic nervous system. It is therefore important that this is also investigated in healthy control subjects to gain a better understanding of which biological changes are normal and which changes may be involved in the symptoms of patients with ME/CFS.

Participants will:

  • Undergo an exercise test (to stress the mitochondria) and an orthostatic test (to stress the autonomic nervous system)
  • Fill in questionnaires
  • Undergo blood collection

Studieöversikt

Detaljerad beskrivning

ME/CFS is a debilitating disease with unknown pathophysiology. Mitochondrial dysfunction has been proposed as a potential pathophysiological mechanism because the mitochondria are important for energy metabolism. Moreover, patients with mitochondrial diseases experience similar symptoms as patients with ME/CFS, including fatigue, pain and autonomic symptoms. However, literature reports conflicting results regarding mitochondrial dysfunction in patients with ME/CFS. As ME/CFS patients present with a broad range of symptoms, subgrouping them might provide new insights.

Next to mitochondrial dysfunction, the involvement of the autonomic nervous system (ANS) has been proposed as it can be linked to common symptoms such as autonomic symptoms, post-exertional malaise (PEM) and cognitive impairments. Recently, ME/CFS patients were subgrouped into autonomic phenotypes. The presence of autonomic symptoms in patients with mitochondrial diseases highlights that there is a link between the mitochondria and ANS. Although the nature of this link remains unclear, a recent animal study showed that activation of adrenergic receptors - the binding sites of catecholamines (i.e. messengers of the ANS) - increased the production of reactive oxidative species, which are in turn known to influence autonomic function, damage the mitochondria, and regulate mitochondrial DNA methyltransferase (DNMT) expression. Mitochondrial DNMTs are responsible for mtDNA methylation (mtDNAm), which directly affects mitochondrial gene expression and could thus have a major impact on mitochondrial function. Interestingly, Buyn et al. reported that heart rate variability, an important marker to subgroup patients with ME/CFS into autonomic phenotypes, was associated with mtDNAm in a study investigating air pollution in 48 healthy males.

This raises the question whether mitochondrial dysfunction in patients with ME/CFS depends on to which autonomic phenotype they belong and whether this relation can be explained by mtDNAm, which is influenced by reactive oxygen species production upon adrenergic receptor activation. Consequently, this relation may lead to autonomic phenotype-dependent mitochondrial dysfunction. Hence, this project entails a cross-over study designed to clear the conflicting results regarding mitochondrial dysfunction in patients with ME/CFS by subgrouping them into autonomic phenotypes.

The investigators will perform an experimental cross-over study, in which the autonomic phenotypes will be validated and linked to additional biological information (i.e., mitochondrial (dys)function and mitochondrial DNA methylation). Study participants will visit the hospital twice with two weeks in between the visits. During each visit, autonomic, clinical and biological outcomes will be assessed before and after the experimental procedure, which include a single bout of submaximal exercise (Aerobic Power Index) to create a high-energy demand situation and stress the mitochondria, and an orthostatic test (Active Standing test) to stress the autonomic nervous system (ANS). The order of these experimental procedures is defined by randomly dividing all participants into two groups. Additionally, this project will assess the presence and severity of post-exertional malaise (PEM) 24h and 7 days after the experimental procedure via online assessments allowing the investigators to determine whether autonomic phenotype and mitochondrial function can predict PEM severity.

Studietyp

Interventionell

Inskrivning (Beräknad)

105

Fas

  • Inte tillämpbar

Kontakter och platser

Det här avsnittet innehåller kontaktuppgifter för dem som genomför studien och information om var denna studie genomförs.

Studieorter

      • Jette, Belgien, 1090
        • Universitair Ziekenhuis Brussel - Vrije Universiteit Brussel

Deltagandekriterier

Forskare letar efter personer som passar en viss beskrivning, så kallade behörighetskriterier. Några exempel på dessa kriterier är en persons allmänna hälsotillstånd eller tidigare behandlingar.

Urvalskriterier

Åldrar som är berättigade till studier

18 år till 70 år (Vuxen, Äldre vuxen)

Tar emot friska volontärer

Ja

Kön som är behöriga för studier

Allt

Beskrivning

Inclusion Criteria:

  • Between the ages of 18 and 70
  • Speak Dutch
  • ME/CFS syndrome (confirmed by a medical diagnosis)
  • Healthy individuals wishing to participate must be currently pain-free and healthy (i.e., participants must not be ill during the period of study participation)

Exclusion Criteria:

  • Pregnant women or women who were pregnant in the past year
  • Persons with a chronic illness such as a rheumatological, endocrine, neurological or psychiatric condition
  • Persons with a history of cancer or heart disease
  • Persons taking medications that affect the autonomic nervous system such as beta blockers

Studieplan

Det här avsnittet ger detaljer om studieplanen, inklusive hur studien är utformad och vad studien mäter.

Hur är studien utformad?

Designdetaljer

  • Primärt syfte: Grundläggande vetenskap
  • Tilldelning: Randomiserad
  • Interventionsmodell: Crossover tilldelning
  • Maskning: Dubbel

Vapen och interventioner

Deltagargrupp / Arm
Intervention / Behandling
Experimentell: Healthy controls

Study participants will visit the hospital twice with two weeks in between the visits. During each visit, autonomic, clinical and biological outcomes will be assessed before and after the experimental procedure, which include a single bout of submaximal exercise (Aerobic Power Index) to create a high-energy demand situation and stress the mitochondria, and an orthostatic test (Active Standing test) to stress the autonomic nervous system (ANS). The order of these experimental procedures is defined by randomly dividing all participants into two groups. Additionally, this project will assess the presence and severity of post-exertional malaise (PEM) 24h and 7 days after the experimental procedure via online assessments allowing us to determine whether autonomic phenotype and mitochondrial function can predict PEM severity.

The Aerobic Power Index (API) will be used to create a high-energy demand situation and stress the mitochondria. Briefly, cycling starts at a constant rate of 70 cycles/min and workload of 25 Watt/min, increasing 25 Watt/min until the patient reaches 75% of the age-predicted maximal heart rate.

Andra namn:
  • Aerobic Power Index

The ANS will be stressed via an Active Standing (AS) test, an ecological valid orthostatic test. Subjects will start in a supine position followed by standing up within five seconds, these instructions will be explained to the subjects prior to the start of the AS test. After standing up, the subjects need to maintain an upright posture quietly for seven minutes, afterwards the patients will be returned to the supine position.

Andra namn:
  • orthostatic test
Experimentell: ME/CFS patients

Study participants will visit the hospital twice with two weeks in between the visits. During each visit, autonomic, clinical and biological outcomes will be assessed before and after the experimental procedure, which include a single bout of submaximal exercise (Aerobic Power Index) to create a high-energy demand situation and stress the mitochondria, and an orthostatic test (Active Standing test) to stress the autonomic nervous system (ANS). The order of these experimental procedures is defined by randomly dividing all participants into two groups. Additionally, this project will assess the presence and severity of post-exertional malaise (PEM) 24h and 7 days after the experimental procedure via online assessments allowing us to determine whether autonomic phenotype and mitochondrial function can predict PEM severity.

The Aerobic Power Index (API) will be used to create a high-energy demand situation and stress the mitochondria. Briefly, cycling starts at a constant rate of 70 cycles/min and workload of 25 Watt/min, increasing 25 Watt/min until the patient reaches 75% of the age-predicted maximal heart rate.

Andra namn:
  • Aerobic Power Index

The ANS will be stressed via an Active Standing (AS) test, an ecological valid orthostatic test. Subjects will start in a supine position followed by standing up within five seconds, these instructions will be explained to the subjects prior to the start of the AS test. After standing up, the subjects need to maintain an upright posture quietly for seven minutes, afterwards the patients will be returned to the supine position.

Andra namn:
  • orthostatic test

Vad mäter studien?

Primära resultatmått

Resultatmått
Åtgärdsbeskrivning
Tidsram
Mitochondrial function will be investigated in patients with ME/CFS compaired to healthy controls at baseline and after a physical exercise test.
Tidsram: Blood collection immediatly before procedure and after

The primary objective is to examine the difference in mitochondrial function between 75 ME/CFS patients and 30 healthy controls. Mitochondrial function will be determined in isolated peripheral blood mononuclear cells (PBMCs). Following the manufacturer's instructions, the Seahorse XF Cell Mito Stress Test Kit (Agilent) will be used to determine the oxygen consumption rate (OCR).

Blood collection immediatly before procedure and after
Autonomic nervous system (ANS) function will be explored in patients with ME/CFS and healthy controls at baseline and after an orthostatic test.
Tidsram: During intervention (approximately 45 mins) in hospital

The investigators will explore autonomc nervous system (ANS) function, enabling clinical stratification of 75 patients with ME/CFS. During the othostatic test or active standing test, the ANS will be monitored with the SOMNOTouch NIBP device, providing a non-invasive continuous blood pressure monitoring.

During intervention (approximately 45 mins) in hospital
Autonomic nervous system (ANS) function will be explored in patients with ME/CFS and healthy controls at baseline and after an orthostatic test.
Tidsram: During intervention (approximately 45 mins) in hospital

The investigators will explore autonomc nervous system (ANS) function, enabling clinical stratification of 75 patients with ME/CFS. During the othostatic test or active standing test, the ANS will be monitored with the SOMNOTouch NIBP device, providing a non-invasive continuous heart rate monitoring.

During intervention (approximately 45 mins) in hospital
Autonomic nervous system (ANS) function will be explored in patients with ME/CFS and healthy controls at baseline and after an orthostatic test.
Tidsram: During intervention (approximately 45 mins) in hospital

The investigators will explore autonomc nervous system (ANS) function, enabling clinical stratification of 75 patients with ME/CFS. During the othostatic test or active standing test, the ANS will be monitored with the SOMNOTouch NIBP device, providing a non-invasive continuous arterial stiffness measurement.

During intervention (approximately 45 mins) in hospital

Sekundära resultatmått

Resultatmått
Åtgärdsbeskrivning
Tidsram
Prediction of severity of post-exertional malaise in patients with ME/CFS.
Tidsram: 24hours after both study visits

Prediction of the severity of early- (24h) post-exertional malaise (PEM) in 75 patients with ME/CFS via online assessments including the Chronic Fatigue Syndrome Symptom List.

24hours after both study visits
Prediction of severity of post-exertional malaise in patients with ME/CFS.
Tidsram: 7 days after both study visits

Prediction of the severity of late-onset (7 days) PEM in 75 patients with ME/CFS via online assessments including the Quality of Life Scale (quality of life, health and other areas of life, min score = not at all, max score=absolutely), Fatigue Severity Scale (min score 0=strongly disagree, max score 6=strongly agree), International Physical Activity Questionnaire and Chronic Fatigue Syndrome Symptom List.

7 days after both study visits

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Studieavstämningsdatum

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Studera stora datum

Studiestart (Faktisk)

21 oktober 2024

Primärt slutförande (Beräknad)

30 november 2026

Avslutad studie (Beräknad)

1 maj 2027

Studieregistreringsdatum

Först inskickad

18 juli 2024

Först inskickad som uppfyllde QC-kriterierna

4 november 2026

Första postat (Faktisk)

9 november 2026

Uppdateringar av studier

Senaste uppdatering publicerad (Faktisk)

9 november 2026

Senaste inskickade uppdateringen som uppfyllde QC-kriterierna

4 november 2026

Senast verifierad

1 november 2026

Mer information

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