Mitochondrial Function in Peripheral Blood Mononuclear Cells, Muscle, and Skin of Long COVID Patients

Official title

Mitochondrial Oxygen Consumption and Substrate Utilisation In Vitro in Peripheral Blood Mononuclear Cells, and In Vivo on Muscle and Skin in Long COVID Patients and Convalescent Individuals: A Case-Control and Diagnostic Accuracy Study

Overview

Mitochondria are structures inside cells that are responsible for producing energy from nutrients through a series of steps, using oxygen. To have an idea of how well the mitochondria can produce energy, we can measure how much oxygen they use. The goal of this study is to: 1. To compare the oxygen use between people with long COVID and people who completely recovered after COVID-19, using three techniques that measure the oxygen use in blood cells, on the skin and in the muscle 2. To test how similar these three techniques are in measuring the oxygen used in the three different tissues Participants will: * Complete surveys, * Wear an activity tracker (7 days), * Undergo several non-invasive tests, and * Donate a blood sample The study will take place in UZ Brussel hospital and will take 2 study visits, approximately 7 days apart.

Primary outcome measures

• Basal Oxygen Consumption rate (pmol O2/min) [Time frame: Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)]
• Tissue Saturation Index (TSI) [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Mitochondrial oxygen tension (mitoPO2) (mmHg/s) [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Mitochondrial oxygen consumption (mitoVO2) [Time frame: Second study visit (minimally 7 days after the first study visit)]

Secondary outcome measures (12)

• Proportion of participants meeting the criteria for PEM [Time frame: Second study visit (minimally 7 days after the first study visit)]
• General fatigue [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Physical fatigue [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Mental fatigue [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Reduced activities [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Reduced motivation [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Severity and impact of fatigue on daily life [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Symptom burden (θ) [Time frame: First study visit]
• Resting Energy Expenditure (kcal/kg body weight/day) [Time frame: Second study visit (approximately 7 days after the first study visit)]
• Basal Oxygen Consumption rate (pmol O2/min) [Time frame: Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)]
• Basal Oxygen Consumption rate (pmol O2/min) [Time frame: Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)]
• Basal Oxygen Consumption rate (pmol O2/min) [Time frame: Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)]

Eligibility criteria

Individuals with long COVID:

Inclusion criteria

• Long COVID diagnosis, based on the WHO definition;
• Presence of long COVID symptoms for a minimum of 6 months.
• History of confirmed or documented SARS-CoV-2 infection.
• Adult (≥18 years of age).
• Post-COVID-19 Functional Status Scale grade 2-4, while they had a grade 0 before the SARS-CoV-2 infection.

Exclusion criteria

• Pre-existing chronic diseases potentially affecting the functional status scale.
• Treatment with metabolism altering drugs.
• > 10 standard units of alcohol (10 grams of alcohol/glass) per week.
• Unable to understand oral and written instructions in Dutch, French or English.
• Allergies to medical adhesive bandages.
• Porphyria and other skin conditions aggravated by sunlight.

Convalescent individuals

Inclusion criteria

• History of confirmed or documented SARS-CoV-2 infection.
• Complete recovery after the SARS-CoV-2 infection, no history of long COVID based on the WHO definition;
• Post-COVID-19 Functional Status Scale \[2\] grade 0 both before the infection and currently.
• Adult (≥18 years of age).

Exclusion criteria

• Pre-existing chronic non-communicable diseases (e.g. hypertension, chronic respiratory diseases, diabetes).
• Treatment with metabolism altering drugs.
• > 10 standard units of alcohol (10 grams of alcohol/glass) per week.
• Unable to understand oral and written instructions in Dutch, French or English.
• Allergies to medical adhesive bandages.
• Porphyria and other skin conditions aggravated by sunlight.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Observational model

Case-control

Study locations

Belgium · 1 center

• Laarbeeklaan 101 — Jette

Identifiers

NCT: NCT07134673 · EC-2025-071 · G075423N

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗