Itaconate Shunt (now called INFa-Itaconate shunt) Part 2!

[MonkeyMan]

All I can say is thank you kindly (these words seem inadequate really) for your thoughts and these links, and for continuing to work so hard on trying to get to the bottom of this. All pwME appreciate it more than you can imagine. Please don't give up!

Dee

I second that! Thank you so much, Dr Phair! 38 and half years dealing with ME/CFS and you give me hope!

 

[Osaca]

Dear Rob Phair,

thanks a lot for being so active on here by answering our questions.

I have a little question on miRNA’s that have been receiving some particular attention recently, in particular in Prusty’s work and the Raman Spectrometry studies.

From what I’ve understood one of the beautiful reasons why the Naviaux-Prusty model could converge to the Davis-Phair model at a midpoint, or at least viral reactivation does not contract your findings/model at that given point, is that the miRNA’s produced by the reactivated viruses could either keep the innate immune system running or could even degrade those parts that are responsible for turning the switch. This degradation of the switch also links quite nicely with what Prusty has recently said and we’re all very keen to soon read his preprint.

My actual question now is how these miRNA correspond to those found in the Raman spectroscopy work done by the teams of Moreau and Morten, or more specifically why they haven’t aligned yet? Is it possible to link their findings or more specifically connect future research in Raman Spectrometry to the work of Prusty? Or is the problem once again that the infected cells which are producing the miRNA are very few in comparison to the healthy cells and as such the very detailed and tailored approach towards mitochondrial fragmentation/ mitochondrial health in presence of reactivated viruses in Prusty work doesn’t align with the goal of creating a more broadly aiming blood based diagnostic test by using Raman Spectrometry?

Oscar

 

[pattismith]

@HTester

Hello Dr Phair, I'm glad to read your current work, it's fascinating!

I have a question, maybe you have an idea?

What happens in chronic Brain Iron Deficiency regarding to Itaconate production?

My purpose is to compare Itaconate Shunt and Brain Iron Deficiency (if we postulate that both can happen in brain cells).

Both Itaconate Shunt and Iron Deficiency block the TCA cycle.

Itaconate Shunt blocks SDH. Itaconate is produced via Aconitase + CAD activities.

Iron deficiency theorically blocks both Aconitase and SDH so Iron deficient cells are supposed to be low in Itaconate;

Itaconate Shunt from the OMF video:

However, in acute iron deprivation, SDH is deprived before Aconitase downregulation, so Itaconate is upregulated at first (moderately):

https://europepmc.org/article/PMC/6635384
https://europepmc.org/articles/PMC6635384/figure/fig3/

 

[pattismith]

@HTester

Sorry I have another question!

iNOS produces NO in macrophages.

NO in macrophages both block Aconitase and PDH...So one would expect itaconate to be downregulated when iNOS is activated;

Do you think iNOS need to be neutralized for the Itaconate Shunt to occur?

https://www.mdpi.com/2218-1989/10/11/429#
https://www.nature.com/articles/s41467-020-14433-7

 

[HTester]

My other question is whether/how the itaconate shunt operating only in certain immune cells is enough to produce PEM?

In many walks of life, your best friend is the one who is always asking you the hard questions. For me, Murph and a few other denizens of PR have played this role for all 7 years I've been here.

First, I completely agree that any theory of ME/CFS must provide an explanation for PEM.

Second, professional immunologists have, apparently, reached the conclusion that only some body cells are cells of the immune system. You can find a terse "immune cells" list in a textbook like Abbas or ChatGPT4.

Those lists effectively limit the cell types that are exposed to cytokines in immunology laboratories every day and worldwide.

I think evolution is far too efficient to have left parenchymal cells (e.g. neurons, hepatocytes, myocytes, enterocytes, etc.) defenseless against invading pathogens. We know that every nucleated cell type expresses the type-I interferon receptor. I'm betting that means all those cells express about 300 genes in response to interferon-alpha activation of that receptor. And one of the most highly expressed of those ISGs will be ACOD1.

Absence of evidence is not evidence of absence. We've got a cell line in the lab that is touted as human and "neuron-like." We ordered it months ago precisely because Murph's question loomed large in my thinking. We're going to expose these cells to IFNa for 24 h and measure IRF1 mRNA, ACOD1 mRNA, IFNa mRNA, and SOCS3 mRNA. The theory predicts we could do this for any human cell type and we will see the innate immune response, including ACOD1.

Forcing any cell type to perform its usual physiological function while supplying insufficient NADH and therefore ATP, seems like a good recipe for PEM.

So, Murph, send me a list of cell types that would convince you the itaconate shunt is not restricted to "certain immune cells." And thanks for asking the hard questions. I'll get to the others soon.

 

[pattismith]

I think evolution is far too efficient to have left parenchymal cells (e.g. neurons, hepatocytes, myocytes, enterocytes, etc.) defenseless against invading pathogens.

Maybe this in vivo Neuron Infection Study have already shown neuron itaconate upregulation?

Abstract​

As long-lived post-mitotic cells, neurons employ unique strategies to resist pathogen infection while preserving cellular function. Here, using a murine model of Zika virus (ZIKV) infection, we identified an innate immune pathway that restricts ZIKV replication in neurons and is required for survival upon ZIKV infection of the central nervous system (CNS).

We found that neuronal ZIKV infection activated the nucleotide sensor ZBP1 and the kinases RIPK1 and RIPK3, core components of virus-induced necroptotic cell death signaling. However, activation of this pathway in ZIKV-infected neurons did not induce cell death.

Rather, RIPK signaling restricted viral replication by altering cellular metabolism via upregulation of the enzyme IRG1 and production of the metabolite itaconate.

Itaconate inhibited the activity of succinate dehydrogenase, generating a metabolic state in neurons that suppresses replication of viral genomes.

These findings demonstrate an immunometabolic mechanism of viral restriction during neuroinvasive infection.

https://pubmed.ncbi.nlm.nih.gov/30635240/

 

[cheeseater]

Thank you for you great work!

After reading the paper where HHV-6 expression leads to mitochondrial fission, it seems clear to me that the purinergic response is upstream the interferon cell response (this is also shown when the P2X7 receptor is stimulated and the IFN response increases).

Then, shouldn't your theory include antipurinergic drugs? Why would lowering the IFN and/or the JAK-STAT signal be effective, if the extracellular ATP is high?

I believe the actual mechanisms have not been so much observed in real life, rather the type of modeling they are using-- shows it would be the case. Depending on how the models are "tuned" the results and mechanisms involved can vary quite a bit. Someone please correct me if I am wrong

 

[annaloecher]

@HTester thank you so much for answering questions!! i have one too:

have you made any progress measuring interferon alpha levels and have they proofen to align with the bell scala like you mentioned in the video? if so would interferon alpha be a future biomarker for mecfs?

 

[annaloecher]

To choose among them or to identify better ones, I think we have to understand what makes ME/CFS a chronic disease. Here are some candidates: 1) a chronic infection, 2) chronic re-activation of DNA-integrated viruses, 3) chronic nutritional deficiencies, and 4) bistability/positive feedback.

If anyone reading this has something to add to the list, I'd appreciate hearing from you. I'm sure you all understand that I'm working on number 4).

In this presentation (minute 24) Prusty talks about high anti-C1q antibodies/ low C1q in mecfs patients. I read a paper saying that C1q deficiency is linked to constitutive type I IFN activation in SLE patients. Could this be another possible reason why interferon alpha JAK STAT signalling is not turning off in mecfs patients?

https://www.jacionline.org/article/S0091-6749(20)30487-5/fulltext

 

[Murph]

This is all part of the innate immune system. There is no mention of T cells or B cells in pathway 2. Normally, the innate immune system is turned off about 4 days after the initial PRR signal. Our hypothesis is that the innate immune system failed to turn off when it was supposed to. We think PWME are sick because a small percentage of body cells are chronically running the itaconate shunt and consequently are not producing sufficient ATP to do their jobs. We're looking for molecular mechanisms that keep ACOD1 up-regulated long after the triggering infection/trauma is gone. One of those mechanisms is chronically elevated IFNa caused by the inherent positive feedback in IFNa signaling.

I'm pretty excited to see people thinking about the innate immune system. It's logical. I think the 4 day timescale you mention could map onto the duration of PEM, and PEM could be inappropriate innate immune activation.

I see also that lipopolysaccharides are a possible way of activating the itaconate shunt. (LPS, also known as endotoxins, is just stuff made by bacteria that live in our bodies. ) It is supposed to stay in the gut. If we have leaky gut, that could get into the bloodstream. It causes all the symptoms of PEM, including microglial activation.

I wouldnt' be surprised if the itaconate shunt is part of the explanation for symptoms of MECFS, but for now I don't see much reason to think of it as upstream. it's just one of the things that happens when innate immunity starts. So I'm pleased to hear you're hunting for possible things that could cause it. Finding them will be key.

To me the idea that the innate immune system is activated (chronically, but then also acutely in PEM) looks plausible. I think the idea of smouldering infection in motor neurons or maybe endothelial cells is plausible, with miRNAs or other immune-activating *stuff* leaking out of those cells when we try to move or when shear stress starts in blood vessels, activating the innate immune response which (after a delay) dials down metabolism and makes us feel terrible.

 

[Oliver3]

What are you thinking murph, is this a smouldering infection, what's going to be different in any treatment plan
I know that's the million dollar question but everyone's tried everything for infection give it take

 

[skandar]

think evolution is far too efficient to have left parenchymal cells (e.g. neurons, hepatocytes, myocytes, enterocytes, etc.) defenseless against invading pathogens. We know that every nucleated cell type expresses the type-I interferon receptor. I'm betting that means all those cells express about 300 genes in response to interferon-alpha activation of that receptor. And one of the most highly expressed of those ISGs will be ACOD1.

I believe all nucleated cells are considered immune cells. See the immunologist, Prof Barker's Immunology lectures. Begin at min 15 if you don't want to listen to entire lecture.

See also: https://pubmed.ncbi.nlm.nih.gov/25988887/

 

[pattismith]

In this 2023 study, it's interesting that long covid patients (LTCS) have a negative correlation with IFN-gamma, IL-6 and IL-10, and that in these patients creatine is positively correlated to TNF-alpha!

I'm sure you already noticed it, it seems in correlation with the TNF alpha/itaconate shunt hypothesis, isn't it?
@HTester

https://www.biorxiv.org/content/10.1101/2023.01.13.523998v1.abstract

 

[Hopeful1976]

One further thought/observation from me-does progesterone dampen the interferon response in some? My ME fatigue/PEM is crushing when I don’t have progesterone in my system (pre ovulation and after it falls again each month). the difference in what I can do in a given day and how fatigued I am is so notable when progesterone is high (obviously not applicable to everyone and not a solution in and of itself). I guess broadly speaking progesterone might dampen the immune system, so it could make sense that progesterone also dampens the interferon response as part of this?

I have this experience too, with progesterone

 

[Judee]

Dr Phair we were wonder if you could look at these threads and give your opinion:

https://forums.phoenixrising.me/threads/nih-research-findings-mtor.89995/
https://forums.phoenixrising.me/threads/prusty-talks-about-his-upcoming-research-on-a-podcast.89842/

 

[Consul]

Could the following analysis be relevant here, it discusses how lowered zinc finger protein in mecfs could lead to reduced control over interferon signalling and the anti viral state.


http://followmeindenmark.blogspot.com/2020/09/zfr-suppresses-antiviral-response-but.html?m=1

 

[datadragon]

Here are some notes I started putting together on both that might be helpful, still a lot to go through.

Itaconate Shunt video https://forums.phoenixrising.me/threads/rob-phair-youtube-video.88163/#post-2405847 In absence of CoA, a B6 deficiency may then also further impede alternative ability to produce energy. Glutamic-oxaloacetic transaminase is a pyridoxal 5 phosphate-dependent (b6) enzyme which exists in cytoplasmic and mitochondrial forms, GOT1 and GOT2, respectively. GOT plays a role in amino acid metabolism and the urea and tricarboxylic acid cycles. See further below on B6. https://www.genecards.org/cgi-bin/carddisp.pl?gene=GOT1

Glutamate decarboxylase 1 gene. Glutamate decarboxylase or glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the decarboxylation of glutamate to GABA and CO2. GAD uses PLP (active B6) as a cofactor

We evaluated the impact of excess fructose on hepatocyte mitochondrial enzymes; citrate synthase (CS), aconitase and glutamate-oxaloacetate transaminase (GOT). Fructose decreased the activities of aconitase and GOT by 35% and 47% respectively https://www.oatext.com/fructose-imp...nzyme-glutamate-oxaloacetate-transaminase.php

A big one. Supplementation with high concentrations of the pyridoxine form of Vitamin B6 competitively inhibits the active Pyridoxal 5' phosphate (P5P) form which actually leads to decreased vitamin B6 function rather than enhancing it. https://www.sciencedirect.com/science/article/abs/pii/S0887233317301959?via=ihub

Zinc, Magnesium, and Vitamin B2 (flavin mononucleotide (FMN); also known as riboflavin-5’-phosphate) are normally needed for the B6 conversion to the active P5P form. Its possible to see high levels of unconverted B6 in tests.

During inflammation or infection, zinc uptake levels are also lowered by also lowering levels of Shank3. we have reported expression of SHANK3 in human enterocytes, where SHANK3 was functionally linked to zinc (Zn) transporter levels mediating Zinc absorption. We detected decreased expression of Zn uptake transporters ZIP2 and ZIP4 on mRNA and protein level correlating with SHANK3 expression levels, and found reduced levels of ZIP4 protein co-localizing with SHANK3 at the plasma membrane. We demonstrated that especially ZIP4 exists in a complex with SHANK3. Zip2 and Zip4 proteins act as key players of zinc absorption in enterocytes. Low enterocytic SHANK3 levels result in diminished Zn transporter levels that could eventually explain reduced Zn concentrations in tissues and organs https://www.ncbi.nlm.nih.gov/pubmed/28345660/

Robert Phair’s IDO metabolic trap hypothesis related notes I started taking.

The IDO1 and IDO2 genes each encode for enzymes that transform an essential amino acid (tryptophan) into an important regulator of the immune system (kynurenine). The main difference is that when tryptophan is at high levels in a cell, the IDO2 enzyme increases its production of kynurenine while, surprisingly, the IDO1 enzyme decreases its production of kynurenine. If you have a problem with IDO2 (mutations in the gene) then you must rely solely on IDO1 to produce kynurenine from tryptophan. If for any reason the tryptophan levels in a cell rise too high, then IDO1 will stop making kynurenine and tryptophan levels will remain high. This is the IDO metabolic trap. the predisposing factors are the damaging mutations in IDO2, the triggering factor is an elevation in tryptophan and the maintaining mechanism is that the IDO1 enzyme can’t convert tryptophan to kynurenine when tryptophan is high, therefore maintaining a high level of tryptophan and the low level of kynurenine in the cell. Dr. Robert Phair Video: https://forums.phoenixrising.me/thr...cfs-research-update-by-dr-robert-phair.76012/ Paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6787624/

The kynurenine pathway, which is often systemically up-regulated when the immune response is activated. IFN-y, which is induced by intense exercise, strongly induces IDO1 expression TRP breakdown was significantly induced by intense exercise as indicated by a decline in TRP levels by 12% (p<0.001) and an increase of KYN levels by 6% (p<0.02), accompanied by an elevation of KYN/TRP by 20% IFN-y is the most important stimulus of indoleamine 2,3-dioxygenase-1 (IDO1) activity although other mainly pro-inflammatory stimuli can do the same. IFN-γ is able to induce both the gene expression and enzymatic activity of IDO-1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4849644/figure/pone.0153617.g002/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4849644/

The 24 hr delay for PEM correlates with IFN-y levels that are known to rise ~24 hrs after exertion. https://forums.phoenixrising.me/threads/the-rbc-nox-hypothesis.77228/#post-2222401

Exercise appears to have different effects on NLRP3 inflammasome (inflammation). In the case of chronic exercise with high intensity such as what occurs in many athletics/sports, a significant INCREASE in expression of gene, NLRP3 and serum levels of IL-1β, IL-18 cytokines were observed. Chronic exercise with light to moderate intensity such as walking however significantly reduced the expression of NLRP3 gene and subsequent serum levels of IL-1β, IL-18 cytokines. So there are differences in intensive vs light exercise with intensive pouring additional fuel on the fire of inflammation. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524053/

Increased synthesis of 5-HT was reported regarding fatigue after exercise. In addition, there is evidence demonstrating that during the development of exercise, levels of TRP hydroxylase and 5-HT elevates https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552521/

Tryptophan is the precursor for the neurotransmitter 5-hydroxytryptamine (5-HT), which is involved in fatigue and sleep. An increase in plasma free tryptophan leads to an increased rate of entry of tryptophan into the brain. This should lead to a higher level of 5-HT which may cause central fatigue. The plasma concentrations of these amino acids were measured in chronic fatigue syndrome patients (CFS) before and after exercise (Castell et al., 1998), and in patients undergoing major surgery (Yamamoto et al., 1997). In the CFS patients, the pre-exercise concentration of plasma free tryptophan was higher than in controls (p < 0.05) but did not change during or after exercise. This might indicate an abnormally high level of brain 5-HT in CFS patients leading to persistent fatigue. In the control group, plasma free tryptophan was increased after maximal exercise (p < 0.001), returning towards baseline levels 60 min later. The apparent failure of the CFS patients to change the plasma free tryptophan concentration or the free tryptophan/BCAA ratio during exercise may indicate increased sensitivity of brain 5-HT receptors, as has been demonstrated in other studies (Cleare et al., 1995). https://pubmed.ncbi.nlm.nih.gov/10721121/

TRPV1 sensitization was maintained by 5-HT/5-HT3A. https://pubmed.ncbi.nlm.nih.gov/31708101/

TNF-α could sensitize TRPV1 by promoting its expression, inhibition of TNF-α synthesis with thalidomide in vivo reversed TRPV1 protein expression https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5840530/

Propofol is the most commonly used intravenous anesthetic for the induction and maintenance of general anesthesia and sedation. propofol causes direct activation of TRPV1 in both capsaicin-sensitive DRG neurons and in CHO-TRPV1 cells. While propofol’s response appears to be partially mediated by its stimulation of PKC, experimental activation of PKC significantly potentiates propofol’s effects on TRPV1. These effects of propofol appear similar to capsaicin-induced activation of TRPV1. http://www.asaabstracts.com/strands/asaabstracts/abstract.htm?year=2004&index=12&absnum=1436

the kynurenine pathway of tryptophan degradation is activated by stress as well as directly by inflammatory factors (Gibney et al., 2013, Liu et al., 2013). Proinflammatory cytokines, including interleukin-1 (IL-1), IL-2, IL-6, interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), have been found to reduce the production of 5-HT by activation of the tryptophan (TRP)-metabolizing enzyme indoleamine-2,3-dioxygenase (IDO) and a less efficient inducer is IFN-α https://www.sciencedirect.com/science/article/pii/S0889159112004965 https://www.sciencedirect.com/science/article/pii/S0166432812008315 https://www.ncbi.nlm.nih.gov/pubmed/3107562 anti-inflammatory cytokines (interleukin [IL]-4, IL-10, and transforming growth factor β) inhibit IDO induction by IFN-γ. The proinflammatory IL-1β and tumor necrosis factor α potentiate this induction and IL-2 acts via IFN-γ. Thus, the IDO status can be assumed to be determined by the balance between proinflammatory and anti-inflammatory cytokines. Interestingly, IFN-γ induction of IDO is potentiated by the synthetic glucocorticoid dexamethasone, which exerts no effect by itself. Nitric oxide (NO) may play an important role in the control of IDO activity. It inhibits the human enzyme.95 Activity of the recombinant human IDO is reversibly inhibited by NO by binding to heme, with the inactivated enzyme complex being the Fe2+-NO-Trp adduct.96 This inhibition may represent an important mechanism of regulating the immune function of IDO https://journals.sagepub.com/doi/full/10.1177/1178646917691938

Butyrate, a short chain fatty acid produced when dietary fiber is fermented in the colon down regulates Indolamine 2,3-Dioxygenase 1 (IDO-1) Expression. the short chain fatty acid (SCFA) butyrate was the main metabolite controlling IDO-1 expression in human primary IECs and IEC cell-lines. https://www.frontiersin.org/articles/10.3389/fimmu.2018.02838/full Butyrate aids in reducing the expression of many pro-inflammatory cytokines, as well as inflammation-inducing enzymes. This would explain how viral outbreaks, inflammation and exercise could have an effect on IDO-1 expression. Exercise enhances butyrate-producing fecal bacteria and increases butyrate production https://www.ncbi.nlm.nih.gov/pubmed/31454784

Regulatory and functional aspects of the kynurenine (K) pathway (KP) of tryptophan (Trp) degradation are reviewed. The KP exists mainly in the liver, which contains all the enzymes necessary for NAD+ synthesis from Trp and is responsible for ~90% of overall Trp degradation under normal physiologic conditions. The KP also exists extrahepatically, but its contribution to Trp degradation is normally minimal (5%-10%) but becomes quantitatively more significant under conditions of immune activation. The KP is rate-limited by its first enzyme, Trp 2,3-dioxygenase (TDO), in liver and indoleamine 2,3-dioxygenase (IDO) elsewhere. Of important relevance to functional differences is that IDO activity, unlike that of TDO, can be substrate inhibited by high [Trp], with a Ki of ⩾200 µM. TDO is regulated by glucocorticoid induction, substrate activation and stabilization by Trp, cofactor activation by heme, and end-product inhibition by reduced nicotinamide adenine dinucleotide (phosphate). IDO is regulated by IFN-γ and other cytokines and by nitric oxide. The KP disposes of excess Trp, controls hepatic heme synthesis and Trp availability for cerebral serotonin synthesis, and produces immunoregulatory and neuroactive metabolites, the B3 “vitamin” nicotinic acid, and oxidized nicotinamide adenine dinucleotide. https://journals.sagepub.com/doi/full/10.1177/1178646917691938

In relation to CNS function, an inverse relationship exists between TDO activity and brain [Trp] and 5-HT synthesis https://academic.oup.com/alcalc/article-abstract/18/4/369/127471?redirectedFrom=fulltext&login=false

TDO is controlled by TRP levels and can be also induced by steroid hormones like cortisol https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3195227/ as Trp inhibits IDO activity at concentrations greater than 50 µM,91 it is unlikely that IDO will be able to process any excess Trp. https://www.ncbi.nlm.nih.gov/pubmed/3488060 TDO is found predominantly in mammalian liver and can be induced by a number of factors including fasting, glucocorticoids, hydrocortisone, L-tryptophan and nicotinic acid. The l-Trp-specific TDO and mainly liver-specific TDO use O2 as cosubstrate and heme as cofactor. Unlike TDO, IDO does not contain an activating site for tryptophan analogues and is induced primarily by the proinflammatory cytokine IFN-γ. IDO also uses the reactive oxygen intermediate (ROI) superoxide as opposed to molecular oxygen as a cofactor https://pubmed.ncbi.nlm.nih.gov/2300969 https://pubmed.ncbi.nlm.nih.gov/6967714

Indoleamine-2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO, also known as TDO2) are two main enzymes involving in the first step of the Kyn pathway. IDO was extensively demonstrated in various organs throughout the body to catabolize most Trp, while TDO is mainly expressed in the liver . Most Trp is catabolized by IDO, which is expressed diffusely in the human body and can be induced by interferon gamma (IFN-γ). For example, IFN-γ activation of mononuclear phagocytes significantly increases IDO1 and flux through the Kyn pathway IDO1 can be induced during infection, where it displays antimicrobial activity and immune regulation. Moreover, some inflammatory cytokines, such as interleukin (IL) 6 and tumor necrosis factor-α (TNF-α), can highly induce IDO1. IDO1 is a 45-kDa monomeric enzyme that contains heme. The Fe2+ form can activate IDO1. TDO can be activated by cortisol and it was also revealed that TDO can be activated by Trp-induced reactive oxygen species. IDO2 is responsible for inflammatory autoimmunity.

IDO1 consumes Trp and produces Kyn metabolites to help attenuate inflammation and maintain tissue homeostasis. Ogiso et al. demonstrated that IDO1 blocked the functions of inflammatory cells and stimulated immunologic tolerance. Additionally, IDO1-expressing DCs, active Tregs and Trp catabolites cooperate to suppress infection in inflammation. Interestingly, IDO1 can downregulate IFN-γ and upregulate IL-6 at the early stage of tumorigenesis to transform the inflammatory environments to immunosuppressive environments Merlo et al. revealed that the activation of autoreactive T and B cells, pathogenic autoantibody production and rheumatoid arthritis development were induced by IDO2. Remarkably, IDO2 expressed in B cells can regulate the function of B cells via interacting with T cells. The role of IDO2 in inflammatory autoimmunity implies that IDO2 is, to some extent, the opposite of IDO1. IDO1 promotes angiogenesis to facilitate cancer growth via downregulating IFN-γ and upregulating IL-6. IDO1 suppresses the immune system to aggravate cancer cell growth, migration and invasion in three ways. A poor prognosis of various cancers has been shown to be related to high IDO1 expression https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6584917/

Unlike IDO1-deficient mice, IDO2-deficient mice have reduced inflammatory cytokines IL-6, IFN-γ, and TNF-α, hematopoietic cytokines GM-CSF and G-CSF, and reduced MCP-1 relative to wt mice. These data again point to the pro-inflammatory function of IDO2 and identify IDO1 and IDO2 as nonredundant players in inflammatory responses. Accumulating evidence indicates that IDO2 acts as a pro-inflammatory mediator of autoimmunity, with a functional phenotype distinct from IDO1. IDO2 is expressed in antigen-presenting cells, including B cells and dendritic cells, but affects inflammatory responses in the autoimmune context specifically by acting in B cells to modulate T cell help in multiple model systems https://journals.sagepub.com/doi/pdf/10.4137/CPath.S39930

kynureninase (kynase) is a Vitamin B6 PLP dependent enzyme that catalyses the cleavage of kynurenine (Kyn) into anthranilic acid (Ant). It can also act on 3-hydroxykynurenine (to produce 3-hydroxyanthranilate). This is part of the pathway for the catabolism of Trp and the biosynthesis of NAD cofactors from tryptophan (Trp). The other PLP-dependent enzyme of the KP, KAT, is also subject to inhibition in B6 deficiency.

Trp is not only catabolized by IDO and TDO. Two other important enzymes, TPH1 enzyme (Tryptophan hydroxylase 1 ) and TPH2 enzyme (Tryptophan hydroxylase 2), are involved in Trp catabolism via a pathway that ultimately leads to the synthesis of serotonin and dopamine, two important neurotransmitters. https://bpsbioscience.com/ido-tdo-pathway

Tryptophan converts to 5-hydroxytryptophan with the enzyme Tryptophan Hydroxylase (Folate, Iron, B3, Calcium and Tetrahydrobiopterin (BH4). 5-hydroxytryptophan, also known as 5-HTP requires zinc, magnesium, vitamin b6 and copper to convert into serotonin via Dopa Decarboxylase enzyme. https://ojrd.biomedcentral.com/articles/10.1186/s13023-020-01379-8 https://understand-andcure-anxietya...pression.com/images/MelatoninCopperBlocks.jpg

 

[datadragon]

One further thought/observation from me-does progesterone dampen the interferon response in some? My ME fatigue/PEM is crushing when I don’t have progesterone in my system

progesterone has been shown to attenuate the inflammation-induced activation of indoleamine-2, 3-dioxygenase (IDO) and to reduce tryptophan catabolism to kynurenine and to neurotoxic metabolites, all relevant for neuro-inflammatory diseases. As a consequence, IDO inhibition helps to maintain the cellular tryptophan pool and to direct tryptophan catabolism toward the serotonin pathway. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8538505/

We have treated primary human macrophages with progesterone in the presence and absence of inflammatory cytokine interferon-gamma (interferon-γ) that is known to be a potent inducer of regulating the KP enzyme. We found that progesterone attenuates interferon-γ-induced KP activity, decreases the levels of the excitotoxin quinolinic acid, and increases the neuroprotective kynurenic acid levels. We also showed that progesterone was able to reduce the inflammatory marker neopterin. These results may shed light on the gender disparity in response to inflammation https://pubmed.ncbi.nlm.nih.gov/27980422/

The naturally occuring neurosteroid progesterone metabolite allopregnanolone prevents the activation of pro-inflammatory proteins important for gene regulation, as well as the creation of cytokines, which are known to be involved in many different inflammatory conditions. Allopregnanolone also tamps down chemokines and cytokines, such as NFkB, HMGB1, MCP-1 and TNF-a, all of which are part of the immune system and involved in many different inflammatory diseases. Allopregnanolone substantially blocked, or inhibited, the LPS-induced TLR4 activation in macrophages, which are found in white blood cells and part of the immune system, including in the brain. In macrophages, the TLR4 protein is part of a proinflammatory response that leads to the production of pro-inflammatory cytokines https://medicalxpress.com/news/2019-02-scientists-neuroactive-steroids-dampen-inflammatory.html Allopregnanolone is a potent enhancer of the actions of the inhibitory transmitter GABA at GABAA receptors. Neurosteroids, and specifically allopregnanolone and its isomer pregnanolone, act as endogenous potent, positive, allosteric modulators of the action of γ-aminobutyric acid (GABA) at GABA type A (GABAA) receptors (Puia et al., 1990; Majewska et al., 1986; Pinna et al., 2000). https://pubmed.ncbi.nlm.nih.gov/22654809/ allopregnanolone (ALLO) negatively modulates the hypothalamic-pituitary-adrenal (HPA) axis https://link.springer.com/article/10.1007/s00213-014-3521-6 Allopregnanolone inhibition of TLR4 activation was found in males and females, but inhibition of TLR7 signals exhibited specificity for female donors. https://www.frontiersin.org/articles/10.3389/fimmu.2022.940095/full

Palmitoylethanolamine (PEA) Engages Allopregnanolone Biosynthesis and induced marked antidepressive and antianxiety effects. These effects were mimicked by the PPAR-α synthetic agonists, fenofibrate and GW7647, and were prevented by PPAR-α deletion, PPAR-α antagonists, and neurosteroid-enzyme inhibitors https://www.sciencedirect.com/science/article/abs/pii/S0006322319300812 This could potentially be used as a substitute for progesterone.

Later in the video, 4-aminobutyrate transaminase, also called GABA transaminase or 4-aminobutyrate aminotransferase, or GABA-T is also using active b6 Pyridoxal 5′-Phosphate as a cofactor https://www.jbc.org/article/S0021-9258(18)52824-6/fulltext P5P is available as a supplement since pyridoxine reduces it, however most seem to come in much larger doses than the typical RDA levels which are more like 2mg/day so perhaps taking only a small amount of the larger dose capsules might be helpful if others agree. I now see rosmarinic acid also inhibits this enzyme and found in things like Rosemary and Oregano, mint, salvia, lemon balm, marjoram, oregano, and other species in the Labiatae or Lamiaceae family of plants. certain dietary supplements, including Melissa officinalis (lemon balm), perilla extract, and rosemary extract, are concentrated sources of rosmarinic acid. Rosemary extract is found in alot of food and products, even such as 365 organic mayonnaise which is not in hellmans and applegate chicken breast and mcdonalds sausage in that state may make things worse possibly. http://doi.org/10.1002/ptr.2712 Sugar which has fructose cant be used properly for energy if in this state and further reduces this pathways enzymes function as mentioned so it goes from at least providing energy to making things much worse.

GDH -> A- Ketoglutarate requires B1+B6, decreased by Sulfites, Palmitoyl CoA, GTP, AATP, EGCG, Increased by Leucine, ADP

Regarding chronic CAD: We identified 8 active-site residues critical for CAD function and rare naturally occurring human mutations in the active site that abolished CAD activity, as well as a variant (Asn152Ser) that increased CAD activity and is common (allele frequency 20%) in African ethnicity and 2% heterozygous americans. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6789909/

Interestingly to add, normally Blood Type A genetics I see seem to rely on this glutamate/gaba production of energy as well and have higher glutamate levels. Any studies or info on blood types with CFS? Mitochondrial dysfunction can also occur with a loss of magnesium or the loss of bioavailable copper. ATP is the main source of energy in cells made within most cells of the body, and must be bound to a magnesium ion in order to be biologically active. What is called ATP is often actually Mg-ATP. ATP is made within the cell through three steps. Step one is glycolysis that yields 2 ATP. Step two is the Kreb’s Cycle that yields 2 ATP. Step three is the electron transport chain that yields 34 ATP. The greatest yield of ATP is found in the electron transport chain in the third step. Bioavailable copper (attached to ceruloplasmin) is necessary for the electron transport chain to operate and so when bioavailable copper is low mitochondria dysfunction also results. Most of the ATP in neurons is derived from oxidative metabolism, and cytochrome c oxidase (COX) is a critical energy-generating enzyme. It is an integral protein of the inner mitochondrial membrane, catalyzing the final step of oxidative metabolism. Cytochrome c oxidase, the terminal oxidase in the electron transport chain, is copper dependent https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2775551/ https://pubmed.ncbi.nlm.nih.gov/9185337/ Copper also requires Zinc, Vitamin A, and Magnesium for ceruloplasmin) and why copper transport becomes dysregulated after prolonged inflammation, a loss of bioavailable copper for the body to utilize, and a buildup of unbound copper. Iron cant be absorbed and utilized without bioavailable (usable) copper. Iron also requires Ceruloplasmin, a copper-containing plasma enzyme which catalyzes the oxidation of the ferrous ion to ferric ion, and thereby enables iron to be trapped by transferrin (a protein transporting iron in the blood). It is then transported to tissues for the synthesis of iron-containing compounds, especially hemoglobin.
-David L (DataDragon)

 

[datadragon]

Another big link I think:

Adenosine inhibits activity of hypocretin/orexin neurons by the A1 receptor in the lateral hypothalamus: a possible sleep-promoting effect. https://pubmed.ncbi.nlm.nih.gov/17093123/

Orexin/receptor pathways play vital regulatory roles in many physiological processes, especially feeding behavior, sleep–wake rhythm, reward and addiction and energy balance.

Electrophysiological experiments have been used to identify factors that regulate orexin neurons. Recordings from transgenic mice expressing GFP in orexin neurons demonstrate that agonists of ionotropic glutamate receptors activate orexin neurons, while glutamate antagonists inhibit their activity. These results indicate that orexin neurons are tonically activated by glutamate. In addition, monoamine neurotransmitters such as dopamine, noradrenaline, and serotonin (5-HT) hyperpolarize and inhibit orexin neurons via alpha 2-adrenergic and 5-HT1A receptors. Other factors that reportedly influence the activity of orexin neurons include corticotrophin-releasing factor, ATP, neuropeptide Y, and physiological fluctuations in acid and carbon dioxide levels. It should be noted that factors involved in feeding (such as glucose, ghrelin, and leptin) inhibit the activity of orexin neurons https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4345701/

The studies showed that orexins may directly excite serotonin (5-HT) neurons by activating K+ leak currents or Na+-dependent NSCCs https://pubmed.ncbi.nlm.nih.gov/11166339/ Unexpectedly, at higher concentrations, orexins indirectly inhibit 5-HT neurons by exciting GABAergic interneurons https://pubmed.ncbi.nlm.nih.gov/12417670/

Adenosine and INF(a) synergistically increase ifn-gamma (y) production of human NK cells. Here we show that the adenosine A(3) receptor agonist iodobenzyl methylcarboxamidoadenosine potently inhibited proliferation, IFN-gamma production, and cytotoxicity of activated human lymphoid cells. Stimulation of the A(3) receptor also caused apoptosis of activated PBMC. However, when PBMC were stimulated with IFN-alpha, adenosine did not decrease, but synergistically increased, the IFN-gamma production of NK cells. https://pubmed.ncbi.nlm.nih.gov/19095736/

Adenosine A3AR stimulation inhibits the respiratory burst, interleukin (IL) 1β, TNF-α, chemokine macrophage inflammatory protein (MIP) 1α, interferon regulatory factor 1, iNOS (inducible nitric oxide synthase), and CD36 gene expression. However, adenosine reduced the expression of adhesion molecules on monocytes and decreased cytokine production, effects that were potentiated by an A3AR antagonist. In addition, A3AR stimulation increased TNF-α production in activated macrophages https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5756520/

The adenosine A3 receptor, also known as ADORA3, is an adenosine receptor, but also denotes the human gene encoding it. Adenosine A3 receptors regulate serotonin transport via nitric oxide and cGMP. Activation of an A3 adenosine receptor results in an increase of 5-hydroxytryptamine (5HT) uptake in RBL cells, due to an increase in maximum velocity (Vmax). The A3 adenosine receptor-stimulated increase in transport is blocked by inhibitors of nitric oxide synthase and by a cGMP-dependent kinase inhibitor. In fact, compounds that generate nitric oxide (NO) and the cGMP analog 8-bromo-cGMP mimicked the effect of A3 receptor stimulation, suggesting that the elevation in transport occurs through the generation of the gaseous second messenger NO and a subsequent elevation in cGMP. https://pubmed.ncbi.nlm.nih.gov/7525554/

Orexin A strongly ameliorated ongoing EAE, limiting the infiltration of pathogenic CD4+ T lymphocytes, and diminishing chemokine (MCP-1/CCL2 and IP-10/CXCL10) and cytokine (IFN-γ (Th1), IL-17 (Th17), TNF-α, IL-10, and TGF-β) expressions in the CNS. https://pubmed.ncbi.nlm.nih.gov/30894198/

 

[datadragon]

We recently reported that elevated blood lactate levels at rest in a subgroup of ME/CFS patients were associated with more severe PEM https://www.nature.com/articles/s41598-019-55473-4

The effect of L-lactate was stereo-selective. D-lactate (400 μM) did not trigger Norepinephrine NE release but completely blocked the stimulatory action of L-lactate https://www.nature.com/articles/ncomms4284

orexin neurons are excited by lactate indicating that these neurons may rely on lactate as a main energy source. Orexin neurons are lactate sensors. Firing rate is sensitive to the level of extracellular lactate. lactate disinhibits and sensitizes these neurons for subsequent excitation.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6634592/

to examine the role of serotonin (5-HT)(1A) receptors in brain energy metabolism in response to stressors...stress-induced increase in lactate metabolism is partly regulated by 5-HT(1A) receptors both in cortical and limbic regions. https://pubmed.ncbi.nlm.nih.gov/16596399/

D-lactate is a primary metabolite in gut bacteria. recent studies have suggested that D-LDH is expressed in human and mammalian mitochondria https://www.nature.com/articles/s41392-022-01151-3
D-lactate is both produced and metabolized within human cells, albeit in tiny amounts compared to that of L-lactate. Metabolic production of D-lactate in human cells is the result of the methylgloxal pathway, a minor off-shoot pathway of glycolysis that results in nanomolar production of methylgloxal, a toxic product that is converted to D-lactate. In the absence of D-LDH, human cells can metabolize D-lactate to pyruvate by the action of the mitochondrial enzyme D-2-hydroxyacid-dehydroganse
https://acutecaretesting.org/en/art...ctate-clinical-significance-of-the-difference

Influenza A induces lactate formation to inhibit type I IFN in primary human airway epithelium​

we here demonstrate that infection with both IAV and SARS-CoV-2 resulted in distinct metabolic changes including increases in lactate dehydrogenase A (LDHA) expression and LDHA-mediated lactate formation. Interestingly, LDHA regulated both basal and induced mitochondrial anti-viral signaling protein (MAVS)-dependent type I interferon (IFN) responses to promote IAV, but not SARS-CoV-2, replication. Our data demonstrate that LDHA and lactate promote IAV but not SARS-CoV-2 replication by inhibiting MAVS-dependent induction of type I IFN in primary human airway epithelium. At 48 hours of infection, distinct changes in several intermediates in both glycolysis and the citric acid cycle were observed in response to infection. IAV infection led to increased formation of lactate, succinate, fumarate, and malate, while the amounts of pyruvate and alpha-ketoglutarate were decreased. We detected no distinct changes to phosphoenolpyruvate and citrate. These results indicated an increased metabolic flux from pyruvate to lactate and from alpha-ketoglutarate to succinate, fumarate, and malate. https://pubmed.ncbi.nlm.nih.gov/34746710/

leptin robustly inhibits orexin neurons, causing hyperpolarization and decreasing the firing rate. Ghrelin activates isolated orexin neurons inducing their depolarization and an increase in firing frequency https://pubmed.ncbi.nlm.nih.gov/12797956/

In lab animals, the principal way to activate orexin is by restricting glucose. elevated glucose concentration can block or silence the activity of orexin neurons https://physoc.onlinelibrary.wiley.com/doi/abs/10.1113/jphysiol.2011.217000 https://diabetesjournals.org/diabet...912/Hypoglycemia-Activates-Orexin-Neurons-and

glucose-induced inhibition of orexin neurons exhibits a unique sugar-selectivity signature: It is caused by d-glucose, mannose and 2-deoxyglucose but not by l-glucose, galactose, α-methyl-d-glucoside, or fructose.
Previous studies show that orexin neurons are GI, inhibited by increases and excited by decreases in extracellular glucose in a metabolism-independent manner
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2551664/

Glucose deprivation strongly inhibited IFN-gamma gene expression, whereas IL-2 production was little affected. Inhibition correlated with diminished phosphorylation of p70S6 kinase and eIF4E binding protein 1 and a requirement for de novo protein synthesis, whereas other signaling pathways known to regulate IFN-gamma expression were unaffected. Together, our data reveal that optimal induction of IFN-gamma transcription is a glucose-dependent process https://pubmed.ncbi.nlm.nih.gov/15814691/

25% of fructose consumed turns into lactate, which is hypothesized to have orexin-increasing effects. It was also observed that sucrose ingestion also caused a higher blood lactate response than did glucose https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-9-89

GLP-1 is a gut hormone that can activate/excite orexin neurons in the hypothalamus (which increases orexin). GLP-1 is an incretin; thus, it has the ability to decrease blood sugar levels in a glucose-dependent manner by enhancing the secretion of insulin. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6812410/

Oleic Acid (high for example in olive oil) potently stimulated GLP-1 release. An indirect stimulation of glycolysis is crucial for the OA-induced release of GLP-1. https://www.metabolismjournal.com/article/S0026-0495(15)00295-4/fulltext

Glucagon secretion is inhibited by glucagon-like peptide-1 (GLP-1) and stimulated by adrenaline. These opposing effects on glucagon secretion are mimicked by low (1–10 nM) and high (10 mM) concentrations of forskolin, respectively. We propose that GLP-1 inhibits glucagon secretion by PKA-dependent inhibition of the N-type Ca2+ channels via a small increase in intracellular cAMP ([cAMP]). Adrenaline stimulates L-type Ca2+ channel-dependent exocytosis by activation of the low-affinity cAMP sensor Epac2 via a large increase in [cAMP]. https://core.ac.uk/download/pdf/82623823.pdf

Nondigestible and fermentable dietary fiber, as well as SCFAs themselves, has been shown to increase GLP-1 secretion in humans https://pubmed.ncbi.nlm.nih.gov/20130660/ https://pubmed.ncbi.nlm.nih.gov/19664300/