Altered Fatty Acid Oxidation in Lymphocyte Populations of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, 2023, Maya et al

[Braganca]

https://www.mdpi.com/1422-0067/24/3/2010


Abstract
Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling multisystem illness in which individuals are plagued with fatigue, inflammatory symptoms, cognitive dysfunction, and the hallmark symptom, post-exertional malaise. While the cause of this disease remains unknown, there is evidence of a potential infectious component that, along with patient symptoms and common onsets of the disease, implicates immune system dysfunction.

To further our understanding of the state of ME/CFS lymphocytes, we characterized the role of fatty acids in isolated Natural Killer cells, CD4+ T cells, and CD8+ T cells in circulation and after overnight stimulation, through implicit perturbations to fatty acid oxidation. We examined samples obtained from at least 8 and as many as 20 subjects for immune cell fatty acid characterization in a variety of experiments and found that all three isolated cell types increased their utilization of lipids and levels of pertinent proteins involved in this metabolic pathway in ME/CFS samples, particularly during higher energy demands and activation.

In T cells, we characterized the cell populations contributing to these metabolic shifts, which included CD4+ memory cells, CD4+ effector cells, CD8+ naïve cells, and CD8+ memory cells. We also discovered that patients with ME/CFS and healthy control samples had significant correlations between measurements of CD4+ T cell fatty acid metabolism and demographic data. These findings provide support for metabolic dysfunction in ME/CFS immune cells. We further hypothesize about the consequences that these altered fuel dependencies may have on T and NK cell effector function, which may shed light on the illness’s mechanism of action.

 

[Braganca]

5. Conclusions
Our findings support the theory of a consistently altered bioenergetic state in ME/CFS immune cells, specific to certain immune cell types that rely on fatty acids more heavily than healthy control subjects. This study detected increases in fatty acid oxidation in CD4+ T cells, CD8+ T cells, and NK cells at varying degrees, with CD4+ T cell fatty acid utilization correlating with ME/CFS illness duration. This data indicates that ME/CFS NK cell dysfunction could be in part due to greater levels of lipid accumulation and subsequent fatty acid oxidation. We also propose that the combined metabolic profile of ME/CFS T cells suggests an exhausted T cell state, resulting in reduced effector functions that may contribute to ME/CFS symptom presentation.

 

[ahimsa]

I found this YouTube video about the study, just posted today.

Jessica Maya, graduate student in the lab of Dr. Maureen Hanson, provides a video abstract of a recent publication on fatty acid oxidation in ME/CFS immune cells. Specifically, Maya is lead author of "Altered Fatty Acid Oxidation in Lymphocyte Populations of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome" published in the International Journal of Molecular Sciences. The publication is open access at MDPI: https://doi.org/10.3390/ijms24032010.

 

[Hutan]

Very clear, accessible and nicely presented video, and work out of Maureen Hansen's lab is typically pretty solid.

Jessica Maya says 'it's a known fact that natural killer cells are less cytotoxic in ME/CFS'. I'd love for there to be a solid difference that we could hold on to, but I wasn't sure that we had got to the point where we could say about that NK cell thing that it's 'a known fact'. Hopefully this study sets out the rationale for the assertion.

I look forward to reading the study.

In both circulating CD4+ and CD8+ T cells from patients with ME/CFS, we found increases in fatty acid oxidation under high energetic demands for ATP production compared to healthy controls. Previous metabolic assays in isolated CD4+ T cells, CD8+ T cells, and total PBMCS reported decreased glycolysis in ME/CFS subjects [44,51]. This suggests that fatty acids may be one of the fuels used by T cells to compensate for the lower glycolytic rates observed in this disease.

Metabolic features and immune cell dysfunction in ME/CFS T cells, such as decreased mitochondrial membrane potential, glycolytic impairments, lower granzyme A/perforin production, and now higher levels of fatty acid oxidation, are also consistent with an exhausted T cell state, common in chronic viral infections and cancer [23,51,53,87]. These characteristics are found in individuals experiencing long-term exposure to antigens, subsequently suppressing T cell survival, proliferation, and cytokine production [52,53]. Various groups have studied T cell exhaustion extensively, and abnormal metabolic regulation is not a consequence of this phenomenon but, rather, drives this immune cell state. Inhibition of CPT1a significantly reduced mitochondrial respiration in early exhausted T cells, and the study suggested that fatty acid usage was a survival tool instigated in glucose-limiting environments but was perhaps still not sufficient to support a robust immune response [86]. Blocking inhibitory receptors such as PD-1, CTLA-4 or Lag-3 have reversed this exhausted state in clinical trials of T cells in cancer [88]. Additionally, metformin has been utilized in HIV-induced T cell exhaustion treatment to increase glucose import and subsequent cellular energy production [89]. Meanwhile, knocking out CD36 in Tregs of a hypoxic tumor microenvironment allowed lymphocytes to kill target cells while sustaining homeostasis, pointing to the importance of considering metabolic components like these in therapeutic treatments [90].

 

[SNT Gatchaman]

I look forward to reading the study.

I've read it through once and will watch the video later. Seems pretty informative on first-pass: esp given the evaluation of cell sub-populations.

In addition to the fatty acid markers, we used other cell surface markers to categorize T cells into naïve, effector, late effector memory, and memory cell populations. These experiments were carried out in an effort to locate any hidden sub-populations that could be using fatty acids excessively as fuels but are masked or unobserved in total cell populations.

I also noted the metformin comment with interest, given this thread.

Also wonder what this unstated therapy was...

This signifies that ME/CFS NK cells rely more heavily on long-chain fatty acids for energy during times of stress based on the larger shift in oxygen consumption rate (pmol/min) reported in ME/CFS cells compared to healthy control cells. In the ME/CFS cohort, we utilized two samples from the same ME/CFS patient, one collected before the patient began a therapy and one collected after the therapy had improved their symptoms, according to the clinical surveys. The sample collected after the treatment exhibited much greater fatty acid oxidation than the one collected when the patient was in poorer health

Spoiler: Obligatory

A little more T cells and a little less psychology would be welcome.

 

[Hutan]

In the past, this underfunded and misunderstood disease has occurred in clustered outbreaks, but most cases in recent years have been sporadic [4].

That's bit of an unusual way to put it. I wonder what the incidence of ME/CFS following Covid-19 would be classed as - a clustered outbreak or sporadic?

This knowledge and other substantial evidence imply an infectious agent at work, but its identity remains controversial

Again, a bit odd. There seems to be an assumption that there is one infectious agent that broke out in clusters and now pops up all over the place. And that arguments are being had about which particular infectious agent it is.

The infectious nature of ME/CFS has prompted investigations into the immune system, related cells, and functional capabilities. Numerous studies of cytokine production and immune cell population frequencies in ME/CFS have been conducted but frequently conflict due to the variability of immune characteristics based on age, sex, health status, genetics, microbiomes, nutrition, and other undetermined factors [10]. Nevertheless, correlations have been reported between the illness duration or disease severity and cytokines such as TNF-α, TGF-β, IL-1α, IL-1β, IL-4, IL-6, and IFN-γ in ME/CFS plasma [11,12,13,14,15,16]. Immune cell population findings have shown decreased regulatory T cell (Treg) levels, increased effector memory CD8+ T cells, and decreased terminally differentiated effector CD8+ T cells [17,18]. Functionally, ME/CFS Natural Killer (NK) cell and CD8+ T cell cytotoxicity is diminished compared to healthy subjects [19,20,21,22,23,24]. Although these studies demonstrate immunological dysfunction in ME/CFS lymphocytes, there is still much to learn about the causes and consequences of these findings.
Meanwhile, ME/CFS metabolic markers have drawn interest in general and as prospective biomarkers for diagnosis, particularly due to symptoms such as post-exertional malaise and fatigue. Prior reports in ME/CFS have found evidence of oxidative stress, lower ATP levels, and decreased coenzyme Q10, necessary for ATP production in the electron transport chain [25,26,27].

This discussion about cytokines, decreased Tregs, reduced NK cell and CD8+T cell cytotoxicity is a bit weak I think.
"correlations have been reported between the illness duration or disease severity" - they are different things. We know some of these studies, and the findings aren't very solid. I'm pretty sure that studies that don't support the assertions have been ignored. My heart always sinks when statements like 'decreased coenzyme Q10' are made, when the evidence as it is now just doesn't support statements like that.

The metabolic profile of CD4+ and CD8+ T cells that we observed is consistent with a chronic viral infection and is commonly seen in T cell exhaustion. According to past studies on long-term antigen exposure that result in this exhausted state, the metabolic requirements for T cell activity are permanently changed to favor this suppression of immune response [52]. Particularly, glycolysis is inhibited, and FAO is promoted in T cells in chronic antigen-stimulating environments [53].

The idea is that there is a chronic viral infection and T cell exhaustion. I guess that's plausible. That reference 53 is
Patsoukis, N.; Bardhan, K.; Chatterjee, P.; Sari, D.; Liu, B.; Bell, L.N.; Karoly, E.D.; Freeman, G.J.; Petkova, V.; Seth, P.; et al. PD-1 alters T-cell metabolic reprogramming by inhibiting glycolysis and promoting lipolysis and fatty acid oxidation. Nat. Commun. 2015, 6, 1–13.
That non-ME/CFS study would be worth taking a good look at.

 

[SNT Gatchaman]

PD-1 alters T-cell metabolic reprogramming by inhibiting glycolysis and promoting lipolysis and fatty acid oxidation (2015)

ETA: Thread here

 

[Hutan]

Here's a key result from the 2023 study:


In activated (as opposed to resting) natural killer cells, fatty acid oxidisation is, on average greater than in controls. On the seahorse machine, they applied a chemical that stops the oxidisation of fatty acids and measured the change in oxygen usage per minute. There is quite a lot of overlap.

However they note that one individual's result was high when they were particularly unwell (the circled result at the top of the ME/CFS range), but was low when they were feeling better (the circled result at the bottom of the range). So, it's possible that the ME/CFS results vary a lot, in line with symptom severity.

They also did a flow analysis, where individual cells pass down a channel and are measured. They provided a source of fatty acid (that's the Bodipy, measured in terms of the intensity of a fluorescent marker). The ME/CFS NK cells absorbed, on average, more of the fatty acid relative to the healthy control cells, even when resting.

 

[Sean]

According to image B, the p value for that flow analysis is 0.07.

 

[Hutan]

According to image B, the p value for that flow analysis is 0.07.

Yes, there's lots of overlap, and an outlier in the healthy controls. The sample size is small. It looks like there are two groups in the ME/CFS samples, some had normal fatty acid uptake values and some had increased values.

 

[hibiscuswahine]

Thanks for the analysis @SNT Gatchaman (and Hutan)

The metformin use is very interesting and in line with emerging long covid research, ME clinicians used this for a while but proof wasn’t determined.

Yes I wonder what it is, maybe new therapeutic medication in its infancy….we live in hope……

Spoiler: Obligatory

A little more T cells and a little less psychology would be welcome.

I think they are talking about physical stress from multiple dysregulated systems via metabolic processes, rather than psychology, unless I misread your quote.

 

[SNT Gatchaman]

Sorry, perhaps I should have put it in quotes. I was inverting Wessely's famous line. I.e. if T cell dysfunction were ultimately shown to be fundamental to the pathology then it could be regarded as ironic that his 1989 exhortation was perfectly wrong.

 

[DMissa]

This is cool, in line with what prior work has been suggesting and from a new angle (new cell types, more direct measures of function). I love this lab's work. Immune cells from pwme, in vitro, are definitely seeming to want more fats based on what we can see in the current literature.

I really want to know how and why this is persisting outside of the body.

In any case, really good that this area is receiving attention with more direct measurements of substrate utilisation. We can only draw so many functional inferences from gene expression data (As I have in my past, preliminary work). A few things are on the boil in this space, so it's really exciting.

 

[Milo]

This is cool, in line with what prior work has been suggesting and from a new angle (new cell types, more direct measures of function). I love this lab's work. Immune cells from pwme, in vitro, are definitely seeming to want more fats based on what we can see in the current literature.

I really want to know how and why this is persisting outside of the body.

In any case, really good that this area is receiving attention with more direct measurements of substrate utilisation. We can only draw so many functional inferences from gene expression data (As I have in my past, preliminary work). A few things are on the boil in this space, so it's really exciting.

It's definitely labor intensive work. I believe this work was presented at IACFSME last summer, but I may be wrong. The main author presented something, I remember that.

 

[FMMM1]

I really want to know how and why this is persisting outside of the body.

Thought occurs that sometimes these are artifacts --- not suggesting that in this case.

In any case, really good that this area is receiving attention with more direct measurements of substrate utilisation. We can only draw so many functional inferences from gene expression data (As I have in my past, preliminary work). A few things are on the boil in this space, so it's really exciting.

I'm hoping that GWAS may help to direct research e.g. this looks like it may be a downstream consequence of disease --- I think one suggestion, re cause, was increased bacterial translocation (from the gut) --- MAIT cells --- GWAS may help to identify cause/source.

 

[DMissa]

Thought occurs that sometimes these are artifacts --- not suggesting that in this case.

Unless there is a specific reason for this concern, it could be applied to any scientific observation. Of course, as a reader this is always borne in mind with individual or not yet validated studies, but when you see the same trend across multiple sample types, investigative techniques, research groups and geographical populations it suggests something is actually there imo. Of course, key word in this case being "suggests" not proves! Just my musings!