Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study 2023,Gottschalk ea

Abstract
Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) is a multisystem chronic illness characterized by severe muscle fatigue, pain, dizziness, and brain fog. Many patients with ME/CFS experience orthostatic intolerance (OI), which is characterized by frequent dizziness, light-headedness, and feeling faint while maintaining an upright posture. Despite intense investigation, the molecular mechanism of this debilitating condition is still unknown. OI is often manifested by cardiovascular alterations, such as reduced cerebral blood flow, reduced blood pressure, and diminished heart rate.

The bioavailability of tetrahydrobiopterin (BH4), an essential cofactor of endothelial nitric oxide synthase (eNOS) enzyme, is tightly coupled with cardiovascular health and circulation. To explore the role of BH4 in ME/CFS, serum samples of CFS patients (n = 32), CFS patients with OI only (n = 10; CFS + OI), and CFS patients with both OI and small fiber polyneuropathy (n = 12; CFS + OI + SFN) were subjected to BH4 ELISA. Interestingly, our results revealed that the BH4 expression is significantly high in CFS, CFS + OI, and CFS + OI + SFN patients compared to age-/gender-matched controls. Finally, a ROS production assay in cultured microglial cells followed by Pearson correlation statistics indicated that the elevated BH4 in serum samples of CFS + OI patients might be associated with the oxidative stress response. These findings suggest that the regulation of BH4 metabolism could be a promising target for understanding the molecular mechanism of CFS and CFS with OI.

IJMS | Free Full-Text | Detection of Elevated Level of Tetrahydrobiopterin in Serum Samples of ME/CFS Patients with Orthostatic Intolerance: A Pilot Study (mdpi.com)

 

Does elevated levels indicate a deficiency?

I seem to recall Ron Davis was investigating deficiencies in BH4.

 

https://www.omfcanada.ngo/genetic-and-metabolic-markers-of-bh4-deficiency-in-long-covid/

We have determined that individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome are more likely to have pathogenic variants in BH4 synthesis genes compared to the general population, and we have also identified a corroborating metabolic signature that predicts BH4 deficiency. Oxidative stress during infection can also lead to BH4 deficiency, so there are many potential routes to the same problem. We propose to test whether these genetic markers and other indicators of BH4 deficiency are also present in subjects with Long Covid. If we are successful, we will show that ME/CFS and Long Covid have a common underlying disease mechanism that includes deficiency of BH4.

 

From Wiki:
Tetrahydrobiopterin deficiency (THBD, BH4D) is a rare metabolic disorder that increases the blood levels of phenylalanine. Phenylalanine is an amino acid obtained normally through the diet, but can be harmful if excess levels build up, causing intellectual disability and other serious health problems. In healthy individuals, it is metabolised (hydroxylated) into tyrosine, another amino acid, by phenylalanine hydroxylase. However, this enzyme requires tetrahydrobiopterin as a cofactor and thus its deficiency slows phenylalanine metabolism.

My blood levels of phenylalanine and tyrosine were the lowest markers on my tests.

 

BH4 impacts other cycles and is folate dependent .
Folate may be an issue too.

 

Tetrahydrobiopterin (BH4) is an endogenous cofactor for some enzymatic conversions
of essential biomolecules, including nitric oxide, and monoamine neurotransmitters, and for the
metabolism of phenylalanine and lipid esters.

Over the last decade, BH4 metabolism has emerged as a promising metabolic target for negatively modulating toxic pathways that may result in cell death.

Strong preclinical evidence has shown that BH4 metabolism has multiple biological roles beyond its
traditional cofactor activity. We have shown that BH4 supports essential pathways, e.g., to generate
energy, to enhance the antioxidant resistance of cells against stressful conditions, and to protect from
sustained inflammation, among others.

Therefore, BH4 should not be understood solely as an enzyme cofactor, but should instead be depicted as a cytoprotective pathway that is finely regulated by the interaction of three different metabolic pathways, thus assuring specific intracellular concentrations.

Here, we bring state-of-the-art information about the dependency of mitochondrial activity upon the
availability of BH4, as well as the cytoprotective pathways that are enhanced after BH4 exposure.
We also bring evidence about the potential use of BH4 as a new pharmacological option for diseases
in which mitochondrial disfunction has been implicated, including chronic metabolic disorders,
neurodegenerative diseases, and primary mitochondriopathies.


Pub Date: 2023-05-03
https://www.researchgate.net/public...rin_Beyond_Its_Traditional_Role_as_a_Cofactor

 

This was confirmed by network analysis methods in 2019 https://twitter.com/user/status/1187689018693214209

 

If BH4 expression is high it seems it might be protective of something. They hint at this with oxidative stress, but it might not be that, or not only that. If expression is high but we can confirm deficiency then it might be that its not being expressed enough or that its being over-utilized. Too many maybes, we need more data, though I have not been keeping up to date on any of this.

 

here is the text of an email from Simarron about the bh4 research:

https://simmaronresearch.salsalabs....h4?wvpId=7806213e-6f92-4a32-b0c3-45ebd3e8fe35

 

According to the paper tetrahydrobiopterin (BH4) has not been tested in CFS yet. It is involved in amino acid metabolism and the production of nitric oxide (NO) in endothelium.

These seem to be the main results:

 

https://twitter.com/user/status/1695218895945130348



We have some compelling evidences of impairment in BH4 metabolism. I will stop until that study gets published or funded. However, I can assure the meachanism of BH4 upregulation is very relevant to current understanding of ME/ CFS.

 

https://twitter.com/user/status/1695218335535824929




Regulation of BH4 is a very conserved process in a healthy cell. Deficiency of BH4 is mostly genetic and partly metabolic. BH4 deficiency can be diagnosed with increased phenylalanine, phenylketonuria, dopamine loss, and hypocitrulinemia. None of these defects was found in ME.

Looks like these tweets may have been prompted by @LarsSG

 

BH4 has a half life of 4 hours in healthy adults. In PBS it has a half life of 16 minutes at room temperature and completely destroyed at 90 minutes.

Guess what Simmaron did to some of their samples. Yep, they used PBS.

 

I think BH4 oxidises with air very quickly so likely papers are useless unless they accounted for that. This 2022 study discusses some of the things the authors needed to implement to stabilise BH4 in order to measure it.
Measurement of Tetrahydrobiopterin in Animal Tissue Samples by HPLC with Electrochemical Detection—Protocol Optimization and Pitfalls