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Endothelial dysfunction in ME/CFS

Key findings

  • This study from researchers in Norway found impaired blood vessel function in both small and large vessels in people with ME/CFS.
  • Furthermore, small vessel function as well as clinical symptoms were improved slightly in individuals treated with rituximab for 18 months.
  • These findings add support to the idea that abnormalities in the vascular circulation play a role in the development of ME/CFS.

A significant amount of research over the last 20 years or so has provided evidence of abnormalities in the cardiovascular system of people with ME/CFS. In fact, ME Research UK has supported a growing number of studies exploring this very area, some of which are referenced in this new paper from Dr Miriam Sandvik and colleagues, and published in the journal PLOS ONE.

An essential component of every blood vessel is the endothelium, which is a layer of cells forming their inner lining. The endothelium is involved in controlling the opening and closing of blood vessels, and hence the amount of blood flowing through them. This ensures an adequate supply of blood and oxygen to tissues throughout the body.

The Norwegian study used two different techniques (flow-mediated dilatation and post-occlusive reactive hyperaemia) to measure the function of both large and small blood vessels in 39 people with ME/CFS as well as in a group of healthy controls.

Both these measures of blood vessel function are reliant on adequate endothelial function, and both were significantly impaired in the ME/CFS patients compared with the controls. These findings confirm those of a previous ME Research UK-funded study using the same techniques.

Importantly, this provides greater certainty that there really is a consistent abnormality in endothelial function in people with ME/CFS. But this new study also assessed these patients after they had been treated with rituximab for 18 months.

Although the randomised clinical trial concluded that rituximab was not effective as a treatment for ME/CFS, patients did experience a small improvement in clinical symptoms during the treatment period (as did those treated with placebo). And there was similarly a small improvement in small (but not large) blood vessel function over the same period.

The authors conclude that at least some people with ME/CFS have reduced vascular endothelial function, which may play a role in their clinical symptoms, and that more studies are needed to explore this more thoroughly.

ME Research UK continues to support research investigating the cardiovascular system in ME/CFS, with recent studies from Francisco Westermeier in Austria, Jo Nijs in Belgium and Faisel Khan in Scotland.

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