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“Endothelial dysfunction and herpesvirus activity are two characteristics of ME/CFS pathology that have yet to be officially linked. ” The authors

Epstein-Barr virus

EBV is associated with many diseases: could it be contributing to the blood flow problems in ME/CFS and long COVID as well?

THE GIST

  • Herpesviruses have been mentioned in connection with chronic fatigue syndrome (ME/CFS) for almost 40 years. It wasn’t until coagulation and blood vessel issues showed up in long COVID that clotting became a significant subject of interest in ME/CFS. Could the old and the new somehow be connected?
  • No one has ever connected herpesvirus with reduced blood flows to the brain or the muscles in these diseases but on the face of it, ask: why not? The Epstein-Barr herpesvirus (EBV) has, after all, a large reach. Besides infectious mononucleosis, ME/CFS, and long COVID, the big bad bug – which our bodies cannot get rid of – is associated with 7 autoimmune diseases and a wide variety of cancers.
  • Most doctors focus on EBV reactivation, EBV doesn’t need to replicate to affect our cells. A landmark 2018 paper found even while EBV is latent in a cell it appears to be able to rearrange its genes to put the person at risk for a range of autoimmune diseases.
  • The main focus of this paper is on the endothelial cells lining the blood vessels. These highly active and versatile cells help with gas exchange, nourishment, and waste clearance, and are key inflammation regulators: they keep things moving and the blood vessels healthy.  Any endothelial cell problems, the authors assert, will probably show up in problems in the blood vessels themselves and ultimately in many systems across the body.
  • The authors show how latent herpesvirus infections could be damaging the endothelial cells and triggering clotting. Theyt propose that a herpesvirus infection of the blood vessels leading to the brain as well as the blood-brain barrier could be contributing to the cognitive issues in ME/CFS and long COVID. Indeed studies indicate that damage to the endothelium has been associated with cognitive problems in a wide variety of diseases.
  • A few brain autopsies suggest that herpesviruses or proteins associated with them may have found their way to the brains of people with ME/CFS. (Click here to find out how to donate your brain to the NIH’s Brain Donor Project.)
  • The authors proposed ways to determine if that old bugaboo in ME/CFS – the herpesviruses – are indeed affecting blood flows. They asserted that “a more refined focus on herpesviruses and endothelial function and health in ME/CFS (and Long COVID) is warranted.”
  • Next Up – Interest in EBV and the blood vessels is continuing to grow, and how. Coming up: more evidence of blood vessel dysfunction, “Could natural anticoagulants help?”, a new EBV-focused hypothesis, and the possibility of new EBV drugs.
Herpesviruses have been mentioned in connection with chronic fatigue syndrome (ME/CFS) for almost 40 years. It wasn’t until coagulation and blood vessel issues showed up in long COVID that clotting became a significant subject of interest in ME/CFS.  Could the old and the new somehow be connected?

Pretorius, Kell, and Nunes admit their hypothesis is “novel” but think they might. The Pretorius-Kell South African group has certainly not been shy about their hypothesis that blood clots (coagulation) and blood vessel damage to the endothelial cells play a significant role in both long COVID and chronic fatigue syndrome (ME/CFS). Since 2021, they’ve been prolific – publishing 18 papers on these subjects, including five on ME/CFS.

Now they’re attempting to match up an old bogeyman in ME/CFS – herpesviruses – with a new one in ME/CFS and long COVID – the blood vessels. Their latest, “Herpesvirus Infection of Endothelial Cells as a Systemic Pathological Axis in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome“, with Jean Nunes from the University of Liverpool, proposes that the mighty Epstein-Barr virus might be doing something no one has suspected before: whacking the blood vessels of people with ME/CFS and/or long COVID.

One has to, on the face of it, ask: why not? The Epstein-Barr herpesvirus (EBV) has, after all, a large reach. Besides infectious mononucleosis, ME/CFS, and long COVID, the big bad bug – which our bodies cannot get rid of – is associated with 7 autoimmune diseases and a wide variety of cancers.

Could it also be affecting the blood vessels?

A Link Between the Old and New? Herpesviruses and the Blood Vessels

endothelium

Could herpesvirus infection of thin layer of cells lining the blood vessels – the endothelium – be impacting blood flows?

The idea that EBV affects the blood vessels may be new, but it’s not exactly a long shot. While EBV primarily infects epithelial and B cells, it has long been known to be able to infect the endothelial cells lining the blood vessels, including those in the blood-brain barrier and those found in the brain.  A 2000 study suggested that EBV’s dUTPase protein may be stimulating monocytes/macrophages in contact with endothelial cells to produce inflammation in the blood vessels. Other studies have found that HHV-6 can infect the blood vessels as well.

Recent studies have shown a herpesvirus need not be actively replicating to affect cell functioning, but it has to establish latency in them; i.e. infect them and establish a non-replicating viral reservoir. While both herpesviruses can infect the endothelial cells, only HHV-6, thus far, has been shown to establish latency in them. The authors believe, though, that the evidence warrants assuming that EBV can infect and establish latency in endothelial cells.

While doctors and researchers commonly look for signs of viral reactivation, establishing latency may be the more important factor when it comes to long-lived chronic diseases like ME/CFS, FM, and long COVID.

A 2018 study found that even when EBV was latent (not replicating), it can still promote the development of cancer, and affect gene expression – thus increasing the risk of autoimmune diseases, increase oxidative stress, and increase the production of the IL-6 cytokine that recent studies suggest may play a significant role in ME/CFS and long COVID, and more.

In a 2018 paper, about which John Harley, the lead author, stated “I’ve been a co-author in almost 500 papers. This one is more important than all of the rest put together.”, EBV, was found, in its latent stage, to turn on genes associated with a wide variety of autoimmune diseases. The senior author, Matthew Weirauch, said the finding provided hope that taking down EBV could provide help for many diseases.

“This same cast of characters is a villain in multiple immune-related diseases…So if we could develop therapies to stop them from doing this, then it would help multiple diseases.”

THE Autoimmune Virus? Could a Groundbreaking EBV Finding Help Explain Chronic Fatigue Syndrome (ME/CFS)

It’s clear that the virus is still highly active and is tweaking the cell in various ways during latency. For it to be causing damage to the blood vessels, though, it has to produce proteins that negatively affect them. The authors show several herpesvirus-produced proteins (Epstein–Barr Nuclear Antigens (EBNAs), LMP-1, U-94) can fit that bill.

The Focus

The main focus of this paper is on the endothelial cells lining the blood vessels. These highly active and versatile cells help with gas exchange, nourishment, and waste clearance, and are key inflammation regulators: they keep things moving and the blood vessels healthy.  Any endothelial cell problems, the authors assert, will probably show up in problems in the blood vessels themselves and ultimately in many systems across the body.

In short, the blood vessels provide a way to explain or help explain many of the symptoms found and the many different systems affected in these diseases.

Blood Flows

In the end, it could all be about blood flows (or the lack of them) to parts of the body. Low blood flows mean that the essential energy molecule – oxygen – is not getting to the muscles, brain, etc.

Impaired blood flows have not been a major emphasis in herpesvirus research, but the authors make the case that EBV may be impacting blood flows to the body and the brain, by pointing to several isolated studies suggesting ways herpesviruses may be able to damage the endothelium. They highlight several ways (damage to glycocalyx, fibrosis, cellular junctions) herpesviruses may be playing “contributory roles” to blood vessel problems in these diseases and propose that deeper investigations of vascular tissues be performed.

Coagulation

They seem to be on a bit firmer ground with the idea that herpesviruses may be contributing to the clotting issues in ME/CFS and long COVID. An EBV infection of endothelial cells appears to be able to promote a variety of clotting factors (von-Willebrand factor (VWF), VEGF, and platelet endothelial cell adhesion molecule-1 (PECAM) levels). One interesting study found that HHV-6 infection produced blood clots in the smallest blood vessels that are similar to those found in ME/CFS and long COVID.

Blood-brain barrier

Some evidence suggests herpesviruses may be able to affect the blood-brain-barrier.

Cognition and the Brain

We know that low blood flows to the brain are present in these diseases, but we don’t know why, and multiple possibilities  (autonomic nervous system problems, damage to the endothelial cells linking blood vessels, microclots, low blood volumes) exist.

Now we have a new option – herpesvirus infection of the endothelial cells lining the blood vessels leading to the brain and herpesvirus infection of the blood-brain barrier. Studies outside ME/CFS and long COVID indicate that damage to the endothelium has been associated with cognitive problems in a wide variety of diseases. The authors, in fact, referred to a systematic review that concluded that an “intrinsic” relationship existed between endothelial cell dysfunction and cognitive impairment.

We don’t know much about what, if anything, herpesviruses are doing in the brains of people with ME/CFS and long COVID – we need more autopsy studies for that – but two small studies have found HHV-6 and/or the dUTPase protein produced by EBV in the central nervous systems of people with ME/CFS. They’ve been found in promising areas, as well (the choroid plexus secretes cerebral spinal fluid (CSF), hippocampus and amygdala – part of the limbic system, and dorsal root ganglia – sensory signal processor).

The Prusty Files: HHV-6 Found in the Brains of ME/CFS Patients

More brain autopsies would be a great help in helping to figure out what is going on in the brains of these diseases. If you have ME/CFS or fibromyalgia it’s easy to donate your brain to the NIH’s Brain Donor Project. Find out more about that in the blog below and click here to go to the Brain Donor Project and here to begin the pre-registration process.

The NIH Wants Your ME/CFS or Fibromyalgia Brain, A New Funding Opportunity and other takes from the NANDSC Roadmap Meeting

The dUTPase protein produced by EBV provides an interesting possibility. It’s produced prior to EBV replication, is found in many people with ME/CFS, appears to be able to open the blood-brain barrier, and once inside the brain, seems almost to be guaranteed to cause neuroinflammation.

The Epstein-Barr Virus, Neuroinflammation and Chronic Fatigue Syndrome (ME/CFS)

Last year, a UCSF exercise study found that EBV reactivation was associated with a trend towards reduced exercise capacity in long COVID.

Inflammation, Epstein-Barr Virus and Exercise Intolerance in Long COVID

Question mark

Herpesviruses can clearly impact people with ME/CFS and/or long COVID. Could they be doing that, in part, by affecting blood flows?

The Way Forward

“We presented the idea that a herpesvirus infection of ECs might be an important, over looked phenomenon that can, in part, account for the pathophysiology and symptoms of ME/CFS and, potentially, Long COVID.” The authors

A herpesvirus blood vessel connection in these diseases is unproven but possible. How to show that herpesvirus infections are indeed affecting blood flows? The authors proposed starting with checking the endothelial cells – particularly from the brain’s microvascular blood vessels – as well as the smooth muscle cells lining the blood vessels – for herpesvirus infections.

In the end, they asserted that “a more refined focus on herpesviruses and endothelial function and health in ME/CFS (and Long COVID) is warranted.”

Next Up – Interest in EBV and the blood vessels is continuing to grow, and how. Coming up: more evidence of blood vessel dysfunction, “Could natural anticoagulants help?”, a new EBV-focused hypothesis, and the possibility of new EBV drugs.

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