Preprint Increased circulating fibronectin, depletion of natural IgM and heightened EBV, HSV-1 reactivation in ME/CFS and long COVID, 2023, Liu, Prusty et al

This paper is too complicated for me to unravel but I have a thought that some others might sort out - I rarely get let down by PWME. Fibronectin circulates in plasma and gets included in fibrin clots as I understand it. So measuring it is serum, which is plasma that has clotted and had the clot removed, may not reflect circulating levels. It might reflect some abnormality of clotting I suppose, but since people with ME do not seem to suffer with clotting that much (DVT, pulmonary embolus) I am not sure what to make of that.

 

Agreed, funding and replication studies are desperately needed

And I avoid them like the plague after the one I was speaking about.

 

To add to that levels of cellular Fibronectin are usually extremely low in plasma and only trace amount of it are detactable in plasma. So it isn't clear to me whether the measurements are mainly statements about cellular of plasma fibronectin. Plasma levels of cellular fibroncetin are known to increase if there are problems in the body, I don't know if the same applies to plasma fibronectin.

 

I couldn't determine the disease duration for the ME patients, vs the known 4 yr max LCs. Perhaps some ME are longer duration? Also if ME patients were diagnosed following sub-acute onset during 2020-23, then some may have been asymptomatic/test-negative Covid.

 

Yes. Some ME/CFS patients might also have LC+ME/CFS. Furthermore those patients called HC, never underwent a Covid test, so it isn't even clear how they differ from the no LC group.

 

I think at least some may have pre-dated the pandemic.

That seems to have recruited "between December 2013 and April 2015" (ref)

 

That is correct. I guess I got a little bit confused with the selection of different patients. Thanks for correcting me.

 

https://twitter.com/user/status/1674889750971392001

 

Great commentary @Hutan . I think the most compelling work in the paper is on dUTPase effect on cytoskeleton and mitochondrial morphology - it's just that it has nothing to do with ME. It should probably be in a separate paper that whole section feels tenuously connected to everything else.

This is interesting - don't suppose you have a source for this/ is it known why this would be the case?

Does it need to be that changes in fibronectin or microclots as reported elsewhere has to = coagulopathy? If memory serves they did thromboelastography in one of the pretorius microclots papers and it was normal, and presumably if standard clotting assays prothrombin time etc were abnormal this would have long been known about.

If they're real it seems likely microclots are a generic thing seen in many conditions diabetes, RA, presumably acute infections and so on, and perhaps the same is the case with fibronectin or natural IgM (which they're seeing after covid infection generally it seems). Could these things be a general marker of inflammation or of the immune system fighting something like itself/pathogen/commensal, and is there any established marker that is known to correlate with all these conditions generally?

 

Yes, there's actually even quite a few studies on this subject. It has been shown that blood plasma levels of cellular fibronectin increase after major trauma resulting in vascular tissue damage, after inflammation, in other diseases such as atherosclerosis, ischaemic heart disease, inflammatory arthritis and stroke https://www.sciencedirect.com/science/article/abs/pii/S0022214303000428,https://www.ahajournals.org/doi/full/10.1161/01.STR.0000131656.47979.39,https://www.sciencedirect.com/science/article/abs/pii/S0021915000004901,https://academic.oup.com/rheumatology/article/38/11/1099/1783296#google_vignette.

I think I might have to go through Prusty's preprint again to understand at what points in time he is able to detect cFibronectin, when pFibronectin or when it's just the collection of the two. Since the main message of the paper are fibronectin levels and a response to this, it seems sensible to me to understand what type of Fibronectin is actually being measured.

Since you mentioned RA. The levels in RA seem lower than in some of the above diseases, the last study I cited looked at that. It isn't much evidence, but it shows that there seems to be no uniformity amongst diseases.

What I find a bit unusual is that he finds different levels in men and women, even in HC. Isn't that something that was discussed somewhere on this forum to not be consistent with other studies?

 

In Dec last year we had two good papers, looking at hypercoagulability in the acute and long-Covid situation.

Transcriptional reprogramming from innate immune functions to a pro-thrombotic signature by monocytes in COVID-19 (2022, Nature Communications)
Analysis of thrombogenicity under flow reveals new insights into the prothrombotic state of patients with post-COVID syndrome (2022, Journal of Thrombosis and Haemostasis)

I haven't re-read recently so I don't know if basic clinical assays might have been normal in the post-Covid paper, although I think elevated d-Dimers are common acutely.

The first paper (acute) had this passage —

Fibronectin is important in coagulation. This paper even suggests very important —

Fibronectin maintains the balance between hemostasis and thrombosis (2016, Cellular and Molecular Life Sciences)

Among other things, fibronectin does interact with monocytes, so possibly this could be such a soluble factor in the microenvironment, eg —

Plasma fibronectin can affect the cytokine profile and monocytes/macrophages function in addition to predicting the prognosis of advanced sepsis (2022, The FASEB Journal)
Elevated Fibronectin Levels in Profibrotic CD14+ Monocytes and CD14+ Macrophages in Systemic Sclerosis (2021, Frontiers in Immunology)
Fibronectin‐adherent monocytes express tissue factor and tissue factor pathway inhibitor whereas endotoxin‐stimulated monocytes primarily express tissue factor: physiologic and pathologic implications (2007, Journal of Thrombosis and Haemostasis)

 

Well it seems like I'm not the only one confused by the selection of patients. According to the above Tweet from Prusty either severe LC patients or HC are taken from the Charite, none of which is stated as such in the paper, or did I miss something (perhaps a LC & ME/CFS overlap that is non-specified which would be horribly bad data representation)?

 

I agree that this is an unsubstantiated claim.

More generally, why do we need a biomarker for severity? Severity. is its own thing.

And the fact that fibronectin 1 levels can’t distinguish mild and moderate cases of ME from healthy controls strongly indicates the molecule isn’t playing a major role in the illness.

If the claim is actually that it can identify ME, but only in severe cases, then they need to show comparisons with other diseases it might be confused with. It’s likely that people with many severe chronic illness (and the deconditioning it brings) will have lots of biomolecules that differ from healthy controls.

I just don’t get the concept of a “biomarker for severity”.
as far as I can tell, fibronectin1 has many roles aside from clottin, some of which are poorly understood, so I’m not sure how helpful a clue the association is with ME.

 

I'm probably heavily biased since I don't belong to the mild/moderate group, but I wouldn't have a problem with a biomarker for severity. That would be an outstanding finding, if it indeed measures more than inactivity. Long-Covid patients haven't been sick for too long so a marker might not have to reflect a chronification. Hard to say if you don't know what cohorts he is referring to at which points in time and to what they are compared. Even if there's overlap with other diseases it at least proves that the disease exists (unless it just shows something like you had a Covid infection at some point in time, which some of his data suggested, since then the BPS boys and girls can again argue that your illness is a hysteria to having been sick). I'm not expecting a marker to straight away be something central to the disease, anything no matter how far downstream it is, would already be a substantial improvement.

Is this even a biomarker for severity though?

I have a big problem with inconsistently and randomly splitting up patients differently in different experiments and comparing them to different people in different scenarios until you get a result, without presenting any analysis of what is done. Is this just a monkey with a typewriter type situation?

The graph of a ROC analysis (instead of an actual analysis) was posted by him on Twitter with cohorts that are apparently different to those in the study. This graph is also not part of the preprint. So possibly there's still a lot of data analysis happening in the background that I can't see. I would certainly hope so. Perhaps we'll hear Scheibenbogen comment on these findings soon, especially if she's supplying new data for more analysis. She seems to be very level headed.

 

I really think we need to absolutely stop all fundraising for research into ME, stop participating, and stop spreading calls for donations and participation on social media UNLESS the research is focussed on properly checking out one of the already known potential biomarkers - whether it's Prusty's or another one, provided it's likely to be affordable and practical. If we don't, this circus of small studies that nobody replicates or scales up will go on draining resources and getting nowhere. Meanwhile children are locked up in psych wards in a living hell, families threatened with FII and care proceedings, and people who are Very Severe are suffering preventable malnutrition. It's all because there is no biomarker. They need to identify that and then they can go back to the useful and fascinating playground of pushing back the frontiers of knowledge that may or may not lead to treatments. Focus was perfectly possible in finding vaccines, why not this? PwME need to start saying no. No more money until the researchers get their eyes back on the ball.

 

That's a big caveat, hence the need for disease controls.

But how do we know if it is a disease marker rather than an inactivity marker? I'm sure that's what BPS sceptics would argue.

Regardless of biomarker status, any biomolecule associated firmly with the illness would be helpful.

But BP argues on Twitter that we should take Fibronectin 1 more seriously than other biomarkers because of its biology.
https://twitter.com/user/status/1674703549958168578

Yes, that is the overarching issue! I've been watching biomarker claims come and go since 1996 so I'm looking for something way more impressive than we have so far, starting with independent replication. The field has a biomarker claim problem, IMO.

 

Yep. But recruiting sick controls who are as inactive as us is very challenging. I don’t know anyone who moves as little as me. Even people with cancer seem more active than me.