Itaconate modulates immune responses via inhibition of peroxiredoxin 5, 2025, Tomas Paulenda et al

Hutan said:
Some background:
Poly(I:C), or polyinosinic-polycytidylic acid, is a synthetic double-stranded RNA molecule that mimics the viral infection process . It's used to stimulate the immune system and can trigger an innate immune response by activating Toll-like receptor 3 (TLR3). This activation leads to the production of type I interferon (IFN) and other inflammatory cytokines.

LPS (lipopolysaccharide) interacts with TLR4 (Toll-like receptor 4) to trigger a signaling cascade that initiates an immune response, particularly against Gram-negative bacteria.

Figure 1 from this paper:
Interferon levels are on the y axis.

View attachment 25862
Caption:
Fig. 1 | Itaconate boosts IFNβ production in vitro and in vivo.
a,b, IFNβ release by activated immortalized BMDMs (iBMDMs) pretreated with itaconic acid
(IA; 5 mM), malonic acid (MA; 5 mM), HCl (7.8 mM) (16 h) or media (M) and either non-stimulated (NS) or stimulated for 4 h with LPS (0.1 μg ml−1), R848 (1 μg ml−1), Pam3CSK4 (0.2 μg ml−1), IMQ (5 μg ml−1) or poly(I:C) (20 μg ml−1) (a, n = 8 for LPS, poly(I:C); n = 4 for R848, Pam3CSK4, IMQ and NS;
b, n = 9).
c, Time-course of IFNβ release by BMDMs stimulated with LPS or poly(I:C) as in a for indicated times (n = 4 biological replicates).


Fig 1 a
Pre-treatment of the activated immortalised macrophages with itaconic acid enhanced interferon production, in the presence of LPC and the poly(I:C) (compare the pink itaconic acid treatment with the white media control).

Fig 1c is interesting. I think that used the same set up as for Fig 1a, with the exposure to the LPS or poly(I:C) for 4 hours. The proxy for viral stimulation seems to produce increasing levels of interferon for hours after.

I wonder why the two stimulants have such different effects - perhaps something to do with the receptors. The number of replicates is small but the error bars for the poly(I:C) are tight. There don't seem to be error bars for the LPS.
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If you'd like, I can organize a mass zoom meeting, where I will explain our findings in more detail so that everyone can understand. Would you be interested? We can start a thread to fing out if people like the idea.
 
Utsikt said:
A live call with many participants unfortunately is also outside the reach of many members due to brainfog and/or their PEM «threshold». But it’s a generous offer!
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A lot might be interested, though, and able to watch or even just listen passively - and some might also be able to actively engage. And not all here have ME - some are carers or interested scientists, who wouldn't have those limitations. I agree this is a very generous offer.
 
Hutan said:
But, I think itaconate is mainly expressed in immune cells (so not in muscles and elsewhere). So, would I be right in assuming that the fatigue and other symptoms is not likely to be a direct result of a lack of ATP from the TCA cycle in the immune cells, or indeed (directly) an increase of other things like H2O2 in those cells, but rather the result of the interferons from the immune cells affecting other cell types or some other indirect process?
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I’ve been having the same line of thought—what is interesting to me is that succinate dehydrogenase (one of the TCA enzymes affected by itaconate in immune cells) is known to be modulated by other regulatory mechanisms, some of which are more well-elucidated than others.

This paper follows previous experiments showing that itaconate’s actions on succinate dehydrogenase do not completely explain its phenotypic effect on macrophages.

However, something similar in other cells would create the malate-aspartate shuttle impairment that I’ve been hypothesizing.

So the question is: if the TCA cycle is involved in ME/CFS pathology at all, is it only mediated by itaconate in immune cells which has a knock on effect through immune signaling, or is there a global impairment driving the more constant symptoms of ME which results in a similar (or perhaps worsened, if itaconate compounds the effect) phenotype in macrophages during activity.

In the latter, macrophage signaling would only explain PEM.

[edit: for my part, I am thinking it might be the latter, as part of my evidence for malate-aspartate shuttle impairment comes from reduced levels of NADPH-dependent metabolites, which would be synthesized in the liver, adrenals, and gonads]
 
I understand, you make a good point here. But, what can be done is to record the meeting and people can come back to it and listen to it in bite sized portions on their own pace if interested.
I don't have any proffesional recording equipment, so I wouldn't be able to do production to be published on youtube. But putting it here on the forum for people to listen to would be fine. And I can imagine, there will be lot of common questions. coming from pepople. So, even those not able to join, may get their questions answered.
 
Jonathan Edwards said:
Hi, Tom. This is a somewhat 'philosophical' post but one that tries to get at how we structure our disease models at a high (overview) level. My background is in rheumatoid arthritis where our identification of switches from negative to positive feedback loops helped me identify the B cell depleting agent rituximab as a useful therapy.

ME/CFS is another acquired disease that seems to switch on and often persist, although, like RA, sometimes it switches off. I think there must be a similar point where a negative feedback loop gets diverted to a positive loop which gets stuck. Robert Phair suggested this might occur at the itaconate level in an 'itaconite trap'. I find that intuitively implausible but I am not exactly sure why.

I think my argument would be that we need a plausible acquired cellular regulatory change that persists. For 'acquired' mitochondrial myopathies I understand that to be cells with abnormal mDNA competing out other cells. For RA the shift seems to be the generation of new recombinations of Ig genes that encode 'subversive' antibodies. For cancer it is a malignant clone. For BSE it is prion polymerisation. For psychosis it may be synaptic rearrangement that leads to cycles of abnormal cognition.

Basically, I see three ways that an acquired cellular change can persist and cause system-wide disease. One is a change in DNA - cancer, and also RA. Another is a change in nerve connections - psychosis maybe. The third is something I think people miss out on and I would call supramolecular pattern propagation. This would include amyloid and BSE. It might be the basis of Alzheimer's. The error is perpetuated by a pattern of repeating molecules that self-propagates, a bit like the 'flyers' in Conway's Life Game. It is conceivable that this can occur in musculoskeletal tissues with things like TGF beta binding - what I call the 'Writing on the Wall' model.

And my problem with an itaconite trap is that I don't see how, in practice, you get propagation of a switch from a negative loop to a positive one within the metabolic machinery of a cell. Where have the railway points been switched over? For sure, if the cell has been infected with a retrovirus the DNA can do the switch, but where would there be switches within the metabolic pathways that could persists and also propagate from cell to cell. So I look for ways signalling between cells could be switched. And I guess that although I understood the interest of thinks like ITIMs and STAT kinases I always focused on the outside signals.

But, as has already come up in the discussion, there is of course powerful information in knowing the intracellular signals both because they might be blocked by drugs and because their time courses and cross-interactions may be crucial to the clinical expression of the story. I like the idea that we might be able to pin down the delay of PEM by working out the time course of mediating steps. PEM may be too variable to make that easy but there is no doubt that we are dealing with a signalling mechanism that can take many hours.

There is also the interesting question, raised by Hutan here, as to whether metabolic shifts cause symptoms such as difficulty using muscles, directly, or through invoking neural or other indirect signals.

What I am increasingly confident of is that somewhere in all this interaction between immune and nerve signals and internal cell metabolic shifts lies the answer to ME/CFS. I personally doubt that anyone 'runs out of ATP'. I think more likely some cells tell other cells to go on strike and refuse to use their ATP. But the evidence remains very hard to interpret. Hopefully we will have some genetic clues soon, so now is the time to really focus in on this problem.
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For what it’s worth, some of my literature search turned up that the itaconate response can be triggered by interferon gamma as well. Meaning that if there was a higher than normal level of interferon gamma, it might have the same effect as pre-treating with itaconic acid in these experiments, resulting in an exaggerated response to stimulus (this is where I’m thinking activity itself might be a stimulus).

Interferon gamma production in T cells seems to be dependent on TCA cycle metabolites (citrate/COA) and at least one epigenetic marker (H3K9ac). I have yet to work out the details, but since modulating succinate dehydrogenase has already been shown to affect interferon production, I am trying to see if an induced global TCA cycle abnormality (or perhaps an failure to turn “off” an epigenetic switch) would result in abnormal interferon gamma production, leading to itaconate upregulation in macrophages and macrophage signaling in response to activity leading to PEM
 
For scheduling a Zoom, if you are in St. Louis, probably some time between 9am and 2pm your time would work for most of the people on here (US, UK, West Europe) most of the people on this forum are not working—so don’t worry about avoiding scheduling during normal “working hours”.
 
Jaybee00 said:
some time between 9am and 2pm your time would work for most of the people on here (US, UK, West Europe)
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It'd probably be the middle of the night for our members in Australia and New Zealand, though. They must be something like 15 hours ahead of Central time.
 
Kitty said:
It'd probably be the middle of the night for our members in Australia and New Zealand, though. They must be something like 15 hours ahead of Central time.
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Sorry, I'd missed @paulendat's idea about recording it.

It wouldn't be quite the same for members in the wrong time zone (or just in the wrong sleep cycle!) as they wouldn't be able to ask questions live, but still really interesting.
 
Thank you @paulendat, that is very generous of you.

Jaybee00 said:
For scheduling a Zoom, if you are in St. Louis, probably some time between 9am and 2pm your time would work for most of the people on here (US, UK, West Europe) most of the people on this forum are not working—so don’t worry about avoiding scheduling during normal “working hours”.
Click to expand...
Times at either end of that 9 am-2 pm window in St Louis are most workable for Australian and NZ members e.g. 9 am or 1 pm start time.

But yes, I think some of our questions will have come up on this thread, so they can be covered whether we are there in person or not. With a recording, there's less need to worry about finding a time that suits everyone.

How about, rather than clutter up this thread with admin, the committee has a conversation with paulendat to work out the details and we post back here when we have a date and time?
 
Sasha said:
Perhaps we here could help by suggesting what might be a good screening questionnaire, if @paulendat is interested. And maybe one specifically about PEM. (I'm not offering, I don't know!)
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I like this idea. Since ME/CFS is mostly self reported (correct me if I'm wrong, please) this would be a key step in understanding and categorizing people in a study. We can talk about this in a more detail.
 
paulendat said:
I like this idea. Since ME/CFS is mostly self reported (correct me if I'm wrong, please) this would be a key step in understanding and categorizing people in a study. We can talk about this in a more detail.
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That's correct, ME/CFS is diagnosed on the basis of patients reporting symptoms - there is no diagnostic test.
 
@paulendat @Sasha

we have those CCC, ICC and other diagnostic criteria but no doctors use it. if you get ME/CFS diagnosis it´s mostly after exclusion of all other similar diagnosis.
You go from one doctor to another one, nobody knows what to do and then finally a doctor write that it´s probably ME/CFS and then the other doctors start to write it also. SO it´s something like this how it works here.
But I am sure you will find something smart how to do it. Just let me know if you want me to help to connect with patients communities.
 
or I dont know where @paulendat is doing his research but maybe you can use a ME/CFS biobank or to cooperate with a ME/CFS doctor.
How I already said in our country there is no ME/CFS doctor but just few dozens of kilometers from our border is Wien and there are several ME/CFS doctors. So maybe this is an option.
 
Jonathan Edwards said:
Hi, Tom. This is a somewhat 'philosophical' post but one that tries to get at how we structure our disease models at a high (overview) level. My background is in rheumatoid arthritis where our identification of switches from negative to positive feedback loops helped me identify the B cell depleting agent rituximab as a useful therapy.

ME/CFS is another acquired disease that seems to switch on and often persist, although, like RA, sometimes it switches off. I think there must be a similar point where a negative feedback loop gets diverted to a positive loop which gets stuck. Robert Phair suggested this might occur at the itaconate level in an 'itaconite trap'. I find that intuitively implausible but I am not exactly sure why.

I think my argument would be that we need a plausible acquired cellular regulatory change that persists. For 'acquired' mitochondrial myopathies I understand that to be cells with abnormal mDNA competing out other cells. For RA the shift seems to be the generation of new recombinations of Ig genes that encode 'subversive' antibodies. For cancer it is a malignant clone. For BSE it is prion polymerisation. For psychosis it may be synaptic rearrangement that leads to cycles of abnormal cognition.

Basically, I see three ways that an acquired cellular change can persist and cause system-wide disease. One is a change in DNA - cancer, and also RA. Another is a change in nerve connections - psychosis maybe. The third is something I think people miss out on and I would call supramolecular pattern propagation. This would include amyloid and BSE. It might be the basis of Alzheimer's. The error is perpetuated by a pattern of repeating molecules that self-propagates, a bit like the 'flyers' in Conway's Life Game. It is conceivable that this can occur in musculoskeletal tissues with things like TGF beta binding - what I call the 'Writing on the Wall' model.

And my problem with an itaconite trap is that I don't see how, in practice, you get propagation of a switch from a negative loop to a positive one within the metabolic machinery of a cell. Where have the railway points been switched over? For sure, if the cell has been infected with a retrovirus the DNA can do the switch, but where would there be switches within the metabolic pathways that could persists and also propagate from cell to cell. So I look for ways signalling between cells could be switched. And I guess that although I understood the interest of thinks like ITIMs and STAT kinases I always focused on the outside signals.

But, as has already come up in the discussion, there is of course powerful information in knowing the intracellular signals both because they might be blocked by drugs and because their time courses and cross-interactions may be crucial to the clinical expression of the story. I like the idea that we might be able to pin down the delay of PEM by working out the time course of mediating steps. PEM may be too variable to make that easy but there is no doubt that we are dealing with a signalling mechanism that can take many hours.

There is also the interesting question, raised by Hutan here, as to whether metabolic shifts cause symptoms such as difficulty using muscles, directly, or through invoking neural or other indirect signals.

What I am increasingly confident of is that somewhere in all this interaction between immune and nerve signals and internal cell metabolic shifts lies the answer to ME/CFS. I personally doubt that anyone 'runs out of ATP'. I think more likely some cells tell other cells to go on strike and refuse to use their ATP. But the evidence remains very hard to interpret. Hopefully we will have some genetic clues soon, so now is the time to really focus in on this problem.
Click to expand...
@paulendat Just wanted to bring your attention back to this post by Jonathan.. do you have any comment on the points he raises on the itaconate trap mechanism/ theory?
 
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