The endothelium – a thin layer of cells lining every blood vessel – plays a pivotal role in regulating blood flow, blood clotting, and inflammatory responses. Research suggests that ME/CFS may involve damage to the endothelium leading to endothelial dysfunction (improper functioning of the endothelium), which contributes to disease manifestations.
Below are articles we have written on endothelial dysfunction in ME/CFS –
- Endothelial dysfunction in ME/CFS
Using two techniques to assess endothelial function, Norwegian researchers found significantly impaired function in both small and large vessels in ME/CFS participants in comparison to healthy controls. The study findings support the role of vascular (blood-vessel related) abnormalities in the disease. Although not an effective treatment for ME/CFS, the researchers noted that small vessel function as well as clinical symptoms were improved slightly in individuals treated with rituximab (antibody therapy) for 18 months. - Endothelial dysfunction in ME/CFS compared with long COVID
The study found that both ME/CFS and long COVID participants had significantly impaired endothelial function compared to healthy controls, but the effect size (strength of relationship between groups) was small, raising concerns about the practical significance. There were no significant differences between the two patient groups, suggesting similar vascular issues in ME/CFS and long COVID. The study did have methodological limitations, therefore further research would be needed to clarify findings. - ME Research UK-funded – Increased microRNAs indicate endothelial dysfunction
Early research supported by ME Research UK over 20 years ago explored blood vessel and endothelial function in people with ME/CFS. Since this is an area in which we have a long-established interest, we were keen to support Dr Francisco Westermeier and his colleagues at FH Joanneum University of Applied Sciences in Austria in their plans to look at endothelial function in ME/CFS in more detail. The team found that five microRNAs (small molecules involved in gene expression) involved in nitric oxide (NO) production, crucial for blood vessel function, were elevated in ME/CFS patients, indicating endothelial dysfunction. These microRNAs may also serve as potential biomarkers to identify ME/CFS subgroups. - ME Research UK-funded – Decreased nitric oxide production in endothelial cells exposed to blood from ME/CFS patients
Building on previous research on microRNAs related to endothelial function, Dr Westermeier’s team, in an article written by Dr Romina Bertinat, further explored nitric oxide (NO) production. NO is essential for maintaining a healthy cardiovascular system. The study revealed that endothelial cells (from human umbilical veins) exposed to ME/CFS blood plasma produced significantly less NO and exhibited reduced activity of the enzyme responsible for its synthesis. These findings suggest potential mechanisms underlying the endothelial dysfunction observed in some people with ME/CFS. - Herpesviruses, endothelial dysfunction, and ME/CFS
This review suggests that persistent herpesvirus infection, such as Epstein-Barr virus (EBV) and HHV-6, could contribute to endothelial dysfunction and symptoms of ME/CFS, including cognitive dysfunction. The authors propose that herpesviruses may cause endothelial damage through complex processes involved in latency (becoming inactive), rather than through active infection. The review calls for further research to investigate herpesvirus infection in endothelial cells in ME/CFS patients to gain a better understanding. - ME/CFS, Orthostatic Intolerance, and the Tilt Table Test
A study showed that during tilt table testing in most (91%) participants with ME/CFS and normal heart rate-blood pressure response (i.e. no PoTS), cardiac output (how much blood heart pumps) and cerebral blood flow (how much blood brain receives) were abnormally reduced. Analysing the data patterns, the researchers suggested that the results indicated an “absence of compensatory vasodilation in the cerebral vasculature”, i.e. blood vessels in the brain are not reacting appropriately to a change in body position, which could be an indicator of endothelial dysfunction.
In simple terms –
Every blood vessel in your body has a lining called the endothelium. This lining is involved in important processes such as controlling how well your blood flows or clots. When the endothelium becomes faulty, for example through being damaged by a herpesvirus, this is known as endothelial dysfunction. Endothelial dysfunction has been found to occur in ME/CFS as indicated by tests assessing how well blood vessels change in size, and by levels of molecules known as microRNAs (which play a role in the functioning of your genes). Endothelial dysfunction potentially underlies orthostatic intolerance in ME/CFS (symptoms that worsen when upright), and may contribute to symptoms such as cognitive dysfunction. Further robust research still needs to be done.
