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

[wigglethemouse]

No I'm saying the exact opposite. Itaconate boosts Type I IFN production in activated macrophages as we showed both in vitro and in vivo.

From my understanding of Robert Phairs technical description the innate immune system can affect CAD via interferon-alpha/JAK pathway and that pathway has positive feedback. What you are describing seems to be positive feedback of type 1 interefron's in Macrophages. Does this make sense?

Some scRNA-seq ME/CFS (link) and Long Covid studies have identified monocytes as having significant genetic differences vs health controls, more so than other immune cells, which is why what is happening to Macrophages might be of interest in both diseases.

 

[paulendat]

To the connection to ME/CFS I need to do a bit more reading on that. But from brief look that I could do, I like the itaconate hypothesis a lot. It is fitting and can explain the symptoms. But it needs experimental verification. I can see a connection through it being a self sustaining mechanism, where in presence of itaconate, you get more interferon which can boost itaconate production in surrounding cells.

Irg1 is triggered also with stimuli that do not induce IFNb in macrophages. One can imagine a scenario, ewhere itaconate is induced first and interferon activation happens later, resulting in a stronger response.

First I need to see some things verified by myself. For example:
1. how are CoA levels changing in presence/absence of itaconate.
2. What are the actual levels of itaconyl-CoA in the glial cells uon activation.
3. Can we devise a mouse model of ME/CFS that would help us understand and verify available hypothesis.

I believe we have tools and exertise to answer these questions. But it will take some time.

 

[paulendat]

From my understanding of Robert Phairs technical description the innate immune system can affect CAD via interferon-alpha/JAK pathway and that pathway has positive feedback. What you are describing seems to be positive feedback of type 1 interefron's in Macrophages. Does this make sense?

Some scRNA-seq ME/CFS and Long Covid studies have identified monocytes as having significant genetic differences vs health controls, more so than other immune cells, which is why what is happening to Macrophages might be of interest in both diseases.

The way CAD (I'm more used to IRG1) activation is described is not exhaustive. It is one of the pathways that can induce it. The reason I'm saying "Type I IFN" is that it is group of interferons alpha and beta that both signal through IFNAR receptor.

Yes there is definitely a positive feedback loop fot IFN production. Without it, there is almost no IFN. I can write more on that if you are interested.

 

[jnmaciuch]

However, natural itaconate being a weak electrophile only contributes to NRF2 activation upon LPS activation. In the light of our recent discovery I believe it is only dye to higher production of ROS, rather than itaconate directly activating NRF2 through KEAP1 alkylation like DI or 4OI.

Hi @paulendat, welcome to the forum! It's great to have more people with an immunometabolism background interested in ME/CFS!

I’m very interested in these findings, since I (as a graduate student with ME/CFS) am looking into possible mechanisms by which type I interferon production could be triggered at higher levels than normal after physical exertion in ME/CFS (as an attempt to explain post-exertional malaise, a hallmark symptom of the illness).

I'm just starting to learn about cellular metabolism in-depth, so I’d like to make sure I’m understanding your point correctly here. Are you saying that natural itaconate likely only inhibits interferon production via upregulating ROS generation, which in turn activates the Nrf2 pathway?

If so, in a situation where itaconate is upregulated but ROS production is temporarily inhibited, would you expect that to result in higher levels of type I interferons?

I ask because I'm hypothesizing a (potentially global) weak impairment of the malate-aspartate shuttle in ME/CFS. I am not sure what point would be impaired, but SDH or GOT2 inhibition are options that I am looking into at the moment.

My thought is that if the rate of malate shuttling is impaired, situations with higher ATP demand could not be met by oxidative phosphorylation, as eventually the store of mitochondrial NADH would be depleted faster than it can be replenished. I may be incorrect, but I suspect that a state of reduced mitochondrial NADH would inhibit mtROS generation temporarily since I have read that it is dependent on the proton gradient.

I know that in regular exercise, we see pretty immediate TNF/IL-6/etc. responses from macrophages, but this normally resolves over time without further consequence in healthy subjects. (To that point, I suspect that the same malate-aspartate shuttle mechanism would prevent cortisol production from being ramped up in response). I am not sure if type I interferons would also be upregulated in that situation, but if they are, reliance on ROS for suppression might explain a delayed and prolonged malaise after exertion in ME/CFS.

Would be very curious to hear your thoughts!

 

[paulendat]

@jnmaciuch

I will answer point by point

Are you saying that natural itaconate likely only inhibits interferon production via upregulating ROS generation, which in turn activates the Nrf2 pathway?

No, ROS induced by itacoonate boost IFNb production. Due to it not being strong enough to induce strong NRF2 response.

The induction of NRF2 pathway happens for example in LPS activation where we see a difference between cells producing itaconate (WT) and those lacking itaconate (Irg1-KO). Irg1-KO shows weaker NRF2 activation. This can be explained as itaconate being an activator of NRF2. Or that ROS elevated due to inhibition of PRDX5 by itaconate boost NRF2. However, we need to prove this to be true.

 

[Utsikt]

@paulendat you can use the «multiquote» feature to make it easier to respond to other comments.

There’s a button at the bottom of each comment to add the entire comment, or you can highlight individual sections to only add those. When you have added something to your multiquote list, an «Insert Quotes» button will appear below the text editor box.

An added benefit of the multiquote is that it notifies the people you quote so you don’t have to remember to tag them.

 

[V.R.T.]

@V.R.T.
No I'm saying the exact opposite. Itaconate boosts Type I IFN production in activated macrophages as we showed both in vitro and in vivo.

I'm saying that itaconate derivatives do the exact opposite. But you will not find the derivatives inside the cells or your body. That's the main difference.

Problem is that people confuse (scientist s are the reason) natural itaconate and it's derivatives.

Let me know if this clarifies it or if I should do better.

Thank you that's perfectly clear. I thought I must be getting mixed up somehow!

Brain fog and not being a scientist make these conversations tricky to follow sometimes!

 

[jnmaciuch]

@jnmaciuch

I will answer point by point

Are you saying that natural itaconate likely only inhibits interferon production via upregulating ROS generation, which in turn activates the Nrf2 pathway?

No, ROS induced by itacoonate boost IFNb production. Due to it not being strong enough to induce strong NRF2 response.

The induction of NRF2 pathway happens for example in LPS activation where we see a difference between cells producing itaconate (WT) and those lacking itaconate (Irg1-KO). Irg1-KO shows weaker NRF2 activation. This can be explained as itaconate being an activator of NRF2. Or that ROS elevated due to inhibition of PRDX5 by itaconate boost NRF2. However, we need to prove this to be true.

Thanks for the clarification, I had missed your earlier explanation that interferon I production was also dependent on ROS and misinterpreted your response to Hutan. I’ve had a chance to read the whole paper now, congrats on the great publication!

In that case, it might actually make perfect sense with the delayed (usually 24-48 hrs) aspect of PEM—interferon production (triggered by itaconate) would be limited by any temporary situation which inhibited by ROS production, correct?

 

[paulendat]

In that case, it might actually make perfect sense with the delayed (usually 24-48 hrs) aspect of PEM—interferon production (triggered by itaconate) would be limited by any temporary situation which inhibited by ROS production, correct?

Thank you, I appreciate it.

This is very important thing to answer. The delay can be explained by the fact that expression of Irg1 doesn't really start until 4h post activation for example. Real meaningful itaconate levels happen even later. I would think that the delay would simply be the time needed for itaconate effects to accumulate enough to manifest.

But this is pure speculation on my part.
That is something worth working on.

 

[jnmaciuch]

Thank you, I appreciate it.

This is very important thing to answer. The delay can be explained by the fact that expression of Irg1 doesn't really start until 4h post activation for example. Real meaningful uitaconate levels happen even later. I would think that the delay would simply be the time needed for itaconate effects to accumulate enough to manifest.

But this is pure speculation on my part.
That is something worth working on.

That's very interesting--funnily enough, I noticed quite a change in the time frame of PEM once I started taking a stimulant for ME/CFS. Previously it would take 1-2 days for those symptoms to manifest. On a stimulant, it would take 3-4 hours after starting activity.

Obviously that's just one person's experience, but I've been digging to see if there might be an explanation related to glucose uptake or something else that would be affected in tissue by dextroamphetamine.

Thanks for taking the time to explain! I am quite limited in what I can study in the lab myself, so it is very encouraging for me that someone else is interested in answering the same questions. I look forward to your future work!

 

[tuha]

Hi @paulendat

Happy to see someone from my country who is interested in ME/CFS field. I lead ME/CFS facebook group where is around 1000 slovak and czech patients. I also have a good connection to LC groups in our country. If you find interesting to somehow cooperate with us don´t hesitate to contact me.
Good luck with your research

 

[paulendat]

Hi @paulendat

Happy to see someone from my country who is interested in ME/CFS field. I lead ME/CFS facebook group where is around 1000 slovak and czech patients. I also have a good connection to LC groups in our country. If you find interesting to somehow cooperate with us don´t hesitate to contact me.
Good luck with your research

Hi tuha,
This is wonderful. Can you share who's the long covid group?

We are planning things on the fly at the moment. But this could be an amazing resource in the near future if people would be willing to participate in a study. 1000 people is a great number.

 

[Hutan]

No I'm saying the exact opposite. Itaconate boosts Type I IFN production in activated macrophages as we showed both in vitro and in vivo.

I'm saying that itaconate derivatives do the exact opposite. But you will not find the derivatives inside the cells or your body. That's the main difference.

Problem is that people confuse (scientist s are the reason) natural itaconate and it's derivatives.

Let me know if this clarifies it or if I should do better.

Thanks so much for answering my implied question about the differences in the literature about the impacts of 'itaconate'. That makes good sense. I have referenced your comment in my post upthread where I talked about the differences.

It is terrific to have you here and thank you for your work. I wonder, is there any way we could get access to your paper other than through the paywall?

 

[paulendat]

Thanks so much for answering my implied question about the differences in the literature about the contradictory impacts of 'itaconate'. That makes good sense. I have referenced your comment in my post upthread where I talked about the differences.

It is terrific to have you here and thank you for your work. I wonder, is there any way we could get access to your paper other than through the paywall?

Sorry for that. Open access is crazy expensive.

My paper is also available on researchgate with the fulltext.

https://www.researchgate.net/public...e_responses_via_inhibition_of_peroxiredoxin_5

Let me know if it works for you.

 

[Hutan]

Thank you, I couldn't find a way to the paper through research gate, but another member has given me a copy. I'm looking forward to reading the paper.


In the meantime, I saw a comment elsewhere today about this paper. The person was hypothesising about the itaconate down-regulating energy production, and that being a reason why people with ME/CFS feel fatigued.

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?

 

[Nightsong]

Also a summary of this research in Nature Metabolism's "News & Views" section:

https://doi.org/10.1038/s42255-025-01274-1

 

[Andy]

Also a summary of this research in Nature Metabolism's "News & Views" section:

https://doi.org/10.1038/s42255-025-01274-1

Paywalled unfortunately for me.

 

[Hutan]

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.


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.

To study the effects of endogenous itaconate, we first focused on TLR3 activation of macrophages. In contrast to LPS, poly(I:C)-treated macrophages release significantly larger quantities of IFNβ, especially at late time points (24 h post stimulation) when intracellular itaconate concentration is expected to be the highest (Fig. 1c and Extended Data Fig. 1d).

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.

 

[tuha]

Hi tuha,
This is wonderful. Can you share who's the long covid group?

We are planning things on the fly at the moment. But this could be an amazing resource in the near future if people would be willing to participate in a study. 1000 people is a great number.

There are 2 facebook groups which I know:
ME/CFS Slovensko - myalgická encefalomyelitída / chronický únavový syndróm (950 members)
https://www.facebook.com/groups/661691970549488

Long covid a postcovidový syndrom - ČESKO A SLOVENSKO (4 400 members)
https://www.facebook.com/groups/longcovidczsvk

In these groups you can find patients for ME/CFS or LC studies. What could be problem in Slovakia, that there is no ME/CFS or LC doctor, so there can be a lot of patients who got ME/CFS or LC diagnosis but they dont have it.

 

[Sasha]

In these groups you can find patients for ME/CFS or LC studies. What could be problem in Slovakia, that there is no ME/CFS or LC doctor, so there can be a lot of patients who got ME/CFS or LC diagnosis but they dont have it.

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!)