Mitochondrial enzymes discriminate between mitochondrial disorders and CFS

[Marco]

Bart Smits et al, 2011

Can anyone access the full paper? I've checked the library and it doesn't appear to there.

Here's a link to the abstract. Unfortunately I can't copy and paste from it.

http://www.sciencedirect.com/science/article/pii/S1567724911002133

I'd like to read a little more about the cohort and the discussion of 'mitochondrial content'.

 

[alex3619]

Not the paper in question, but a long paper on mitchondrial disorders can be found at: http://dare.ubn.kun.nl/bitstream/2066/52779/1/52779_biocdifom.pdf

 

[justy]

Hmm, this looks interesting - wonder what it all means? $31 to find out! I cant glean enough info from the abstract. I do wish there was more research done into the mitochondrial problems of PWME.
Justy.

 

[Marco]

Not the paper in question, but a long paper on mitchondrial disorders can be found at :

Hmm, this looks interesting - wonder what it all means? $31 to find out! I cant glean enough info from the abstract. I do wish there was more research done into the mitochondrial problems of PWME.
Justy.

I'm happy for my working theories to be proven wrong and I doubt anyone has been suggesting that ME/CFS is an inherited genetic mitochondrial disease like the MELAS group that often result in early death.

On the other hand there are numerous findings and theories that ME/CFS involves an acquired mitochondrial dysfunction - not necessarily the trigger but possibly as a downstream effect.

What this abstract suggests to me (as much as I can tell from the limited detail) is that there are no problems in the mitochondrial respiratory chain as are found in mitochondrial diseases but that there is a deficit in mitochondrial content.

The latter being consistent with deconditioning?

I'd like to see the full paper before passing judgement.

 

[Dolphin]

Bart Smits et al, 2011

Can anyone access the full paper? I've checked the library and it doesn't appear to there.

Here's a link to the abstract. Unfortunately I can't copy and paste from it.

http://www.sciencedirect.com/science/article/pii/S1567724911002133

I'd like to read a little more about the cohort and the discussion of 'mitochondrial content'.

I notice Knoop & Bleijenberg are two of the authors.
People may remember that they claimed the Lancet PACE Trial paper used a strict definition of recovery.
They're huge CBT-for-CFS fans.
Doesn't mean finding is not valid but wouldn't be surprised if there is a bit of spin.

 

[kaffiend]

I posted the paper in the library.

 

[Marco]

Thanks Alex. That looks like a useful primer (I confess I haven't yet read it all!).

Thanks Dolphin. I can never remember which of the Begian? groups are the psychosocialists.

Many thanks for the paper Kaffiend.

In the meantime I've read a few papers that showed reduced mitochondrial content in patients with type II diabetes/metabolic syndrome where they concluded (on the basis of matched activity levels to normal controls) that this deficit likely preceeded onset rather than resulted from inactivity deconditioning. They also conclude that this does not negate (in the case of these patients) the possibility that mitochondrial content may be improved via exercise.

 

[Astrocyte]

The reduced amount of mito in the muscle (mito content) of CFSers makes sense. Less aerobic activity = less mito content. (Truly sedentary controls are often hard to find - how is this defined in the paper?). And as Marco said, they seem to be saying that though CFS people have got less mitos, they work ok.

But while we also know that CFSers ATP production and complex i, iii and iv activity was higher/better than mito disorders, we dont know (from the abstract) how this compares to ATP production and complex i,iii, iv in healthy controls do we? Fairly important, that.

Do they give absolute values for ATP in healthy, CFSers and mito disorders in the paper?

They don't mention Complex ii in the abstract. It is different from i.iii, and iv but its still important donation of electrons in the RCC. complex II oxidizes succinate to fumarate in the Krebs cycle and is important in membrane potential (among other things). Do they mention complex II in the paper?

 

[alex3619]

I posted this in the library thread earlier:

This uses the Reeves-CDC operationalized CFS criteria (2003), though I have not checked the 2008 paper by Sheeres. So its basically a group of chronic fatigue patients, not ME patients.

Citrate synthase activity was decreased in CFS patients (which means the citric acid cycle is not turning as rapidly). This should imply reduced ATP levels - however they found ATP was normal. This is slightly questionable given what we know about mitochondrial function in other CFS studies using better criteria. Respiratory chain complex activity was also normal. This is the bit after the citric acid cycle that burns up the oxygen and makes ATP.

Their table 2 uses sensitivity toward CFS of 100% for their cut-off value. Say what? With their highly indiscriminate diagnostic criteria? Not only did they fail to use good diagnostic criteria, they somehow want to accept that it will produce data that warrants 100% sensitivity.

It would be interesting to compare their plot data on the graphs of various mitochondrial enzymes and complexes versus other studies on mitochondria in CFS. I have not attempted to do so.

What they want to say is the mitochondria have insufficient metabolites but that everything is working fine. This responds to training in other disorders i.e. exercise. It therefore suggests the low energy is the result of inactivity according to them. It is likely that this study will be interpreted as supporting the use of graded exercise therapy.

What they were saying though is that ATP production can discriminate between CFS and mitochondrial disorders (although not always). I translate this as saying that ATP production discriminates beteen ideopathic chronic fatigue and mitochondrial disorders (though not in all cases). It tells us nothing relevant about ME, except that once again it is possible for these researchers to use the wrong diagnostic criteria despite abundant evidence that it is not valid.

This is another confirmatory piece for the inactivity model of CFS. Its not to be taken seriously in my view, except for the likelihood that some might over-interpret this study to patients with CCC ME/CFS or ICC ME or similar. It is possible to sum up this paper as saying "most chronically fatigued patients do not have a mitochondrial disorder and do not exercise enough".

 

[alex3619]

The reduced amount of mito in the muscle (mito content) of CFSers makes sense. Less aerobic activity = less mito content. (Truly sedentary controls are often hard to find - how is this defined in the paper?). And as Marco said, they seem to be saying that though CFS people have got less mitos, they work ok.

But while we also know that CFSers ATP production and complex i, iii and iv activity was higher/better than mito disorders, we dont know (from the abstract) how this compares to ATP production and complex i,iii, iv in healthy controls do we? Fairly important, that.

Do they give absolute values for ATP in healthy, CFSers and mito disorders in the paper?

They don't mention Complex ii in the abstract. It is different from i.iii, and iv but its still important donation of electrons in the RCC. complex II oxidizes succinate to fumarate in the Krebs cycle and is important in membrane potential (among other things). Do they mention complex II in the paper?

Hi Astrocyte, in the paper they quote complex two and three together. No direct values are given, just two short summary tables with almost no info, just abstracted data.

They do compare to controls, and use two different mitochondrial disorders.

Hmmmm, looking more closely at table one, the AUC range is from 0.42 to 0.90 for ATP with CFS vs. controls. This might mean that some of the patients really had ME, just a minority. On the other hand, the selection criteria involved a neurologist and patients were ruled out if they had neurological signs, (sigh). Maybe someone with more knowledge of stats and AUC ROC curves could comment?

Even more hmmmm, I just realized that 9/16 CFS patients were female, but the 11 healthy controls were all male! Not exactly well matched.

Something even more important, all the studies were based on tissue samples, not real measures in live patients. So they were looking at activity in a lab, not in a person. They also normalized all mitochondrial complex data to citrate synthase levels, I am still not sure what this implies, I am thinking about it. One possible implication is that our low CS levels meant the RCC levels were normalized to too high a value, this is a problem in the methodology.

Bye, Alex

 

[kaffiend]

I don't find muscle biopsies to be the best place to look for mitochrondrial dysfunction in a neurological disorder. It could easily be tissue specific, in the way that Parkinson's involves the dopamine cells of the substantia nigra.

 

[Marco]

Leaving aside the valid criticisms already made (to which I could add that they tested patients without challenging their mitochondrial capacity) there remains the possibility that this is a valid finding. But one that can be interpreted differently.

For the sake of argument lets assume that the mitochondria of ME/CFS patients are functioning properly but there are less of them (the mito density in skeletal muscle is less than controls).

The latter finding actually ties in with previous findings that there is a switch away from mitchondria rich Type I (endurance) muscle fibres to type II (strength) fibres. A needle biopsy would presumably contain both types of fibres but with fewer type I fibres the ME/CFS samples would have less mitochondrial content.

The authors conclude this results from deconditioning (in contrast to the conclusions of the study that found the switch in muscle fibre type).

As discussed many times many of us developed exercise intolerance at a time when we were exercising regularly and strenuously which under normal circumstances would be expected to boost mitochondrial biogenesis particularly in type I endurance fibres. Despite exercising regularly a number of us also report reaching a plateau where we didn't appear to be getting any fitter. Many of us have also remained at least as physically active as the average sedentary control making deconditioning unlikely.

Its easy to conceive that a state of low mitochondrial content might leave an individual predisposed to exceeding the capacity of their muscles to meet the energy demand placed on them at times of high demand (the concept wouldn't be confined to skeletal muscle). Even at rest a lower density of mitochondria means they would have to be working much closer to their peak efficiency.

Many of us have tried mito supplements with no reported 'breakthrough' to my knowledge. If valid, these findings might point to a problem with biogenesis rather than function and might suggest a better place to intervene?

 

[alex3619]

Hi Marco, there is a one line comment in the very first part of results: proportion of type 1 fibers did not vary between groups, with some percentages. They did not find any variation in muscle fiber types:

"The percentage of type I fibers did not differ between groups (controls 44%, CFS 44%, CPEO 43%, A3243G 49%, p=0.588). COX negative and ragged red fibers were only found in CPEO patients (23.4% and 3.4%) and in A3243 (2.7% and 5.2%) patients."

Bye, Alex

 

[Dolphin]

I posted this in the library thread earlier:

This uses the Reeves-CDC operationalized CFS criteria (2003), though I have not checked the 2008 paper by Sheeres. So its basically a group of chronic fatigue patients, not ME patients.

They use the Reeves et al (2003) CFS criteria:

Reeves, W.C., Lloyd, A., Vernon, S.D., Klimas, N., Jason, L.A., Bleijenberg, G., Evengard, B.,
White, P.D., Nisenbaum, R., Unger, E.R., 2003. Identification of ambiguities in the
1994 chronic fatigue syndrome research case definition and recommendations for
resolution. B.M.C. Health Serv. Res. 3, 25.

As the name suggests, these are basically the Fukuda criteria.

The one's that give the 2.54% prevalence are the (weirdly) operationalized version:

Chronic fatigue syndrome--a clinically empirical approach to its definition and study.
Reeves WC, Wagner D, Nisenbaum R, Jones JF, Gurbaxani B, Solomon L, Papanicolaou DA, Unger ER, Vernon SD, Heim C.
BMC Med. 2005 Dec 15;3:19.

However, I still agree with this point (although haven't read the paper yet):

Their table 2 uses sensitivity toward CFS of 100% for their cut-off value. Say what? With their highly indiscriminate diagnostic criteria? Not only did they fail to use good diagnostic criteria, they somehow want to accept that it will produce data that warrants 100% sensitivity.

 

[alex3619]

Hi Dolphin, I was distracted by this line: "According to these criteria patients have to be severely fatigued (operationalised as a score of ?35 on the subscale fatigue of the Checklist Individual Strength) and the fatigue has to last longer than 6 months."

They also had to show no neurological signs. I am unfamiliar with the 2008 paper they cite though.

Bye, Alex

 

[Dolphin]

Hi Dolphin, I was distracted by this line: "According to these criteria patients have to be severely fatigued (operationalised as a score of ?35 on the subscale fatigue of the Checklist Individual Strength) and the fatigue has to last longer than 6 months."

Ok. That's not how Reeves et al (2005) operationalise the criteria.

They also had to show no neurological signs. I am unfamiliar with the 2008 paper they cite though.

Bye, Alex

They're just using the method that was used in another study.

 

[Marco]

Hi Marco, there is a one line comment in the very first part of results: proportion of type 1 fibers did not vary between groups, with some percentages. They did not find any variation in muscle fiber types:

"The percentage of type I fibers did not differ between groups (controls 44%, CFS 44%, CPEO 43%, A3243G 49%, p=0.588). COX negative and ragged red fibers were only found in CPEO patients (23.4% and 3.4%) and in A3243 (2.7% and 5.2%) patients."



Bye, Alex

Thanks Alex - well spotted.

 

[Astrocyte]

Thanks for the info Alex and you make some interesting points which I'll get to later. And agree with much of your post Marco.

I was sent the paper so I took a closer look. There seems to be a bit of a prob with the study design (euphemistically speaking).

The healthy controls were medical students who 'did not play professional sport or do intensive exercise.' In other words some would have done amateur sport (otherwise the would have said they did no sport) and/or moderate exercise (up to 70% vo2 max) otherwise why say 'no intensive exercise.' These healthy controls would certainly have had significantly more mito content than even healthy sedentary controls or merely healthy controls who were active but did no sport. So as Alex pointed out, they're not exactly matched. What are they controlling for? Comparison with healthy sedentary bods would have had more meaning.

More importantly we would expect the mito dysfunction group to be tested against a randomized group of CFSers. But in fact they chose CFSers who they knew, prior to the study, had no mito abnormalities. Quote: "The CFS group was recruited from patients who had undergone a muscle biopsy with measurement of RCC activity for evaluation of a suspected neuromuscular or mitochondrial disorder between 2005 and 2007." They were given a CFS diagnosis when no abnormalities were found. In other words, the researchers knew objectively the outcome of the main point of the study before they started. Am I wrong or is this not really science? (No viable null hypothesis?).

Leaving aside the valid criticisms already made (to which I could add that they tested patients without challenging their mitochondrial capacity) there remains the possibility that this is a valid finding. But one that can be interpreted differently.

Yes, it would have been much more interesting to look at mito when the 48/72 hr fatigue hit.
And I would go for a potentially different interpretation but along the lines of Alex's sense that citrate synthase might be key to this.

More in a bit...

 

[Astrocyte]

To follow on from Alex's thoughts...

Citrate synthase is actually a standard measure of mito content in healthy people. But how valid is it in sick people? Its been questioned, for instance, in developmental and age related studies.

And get this! It's reduced by mood-enhancing medication including Amitryptaline. (You'll know that this is frequently recommended in low dose to improve CFSers sleep, even those without a mood disorder). Yet the researchers make no mention of medication. That would have been a key point to make one way or the other.

Consequently, we have to ask, is it possible to know whether citrate synthase (CS) is reduced because of low mito content or due to an often prescribed medication. (Its interesting that CFSer CS is lower than all groups including mito dysfunction groups).

CFSers might actually have relatively normal mito content, we just dont know.

This becomes a problem because the researchers have quite correctly normalised both ATP production and RCC to citrate synthase (ie citrate synthase as an indicator of mito content).

However, If CS is reduced because of medication rather than reduced mitos, normalisation would give lower values of ATP/RCC too (think I've got that right but happy to be corrected on that). So lower ATP production/RCC could obviously bring the authors conclusion into serious question. Sadly, its too small a study to conclude anything.

And haven't got to the AUC/cut off points/lack of complex II figures yet. Probably I wont. Though the scatter plots seem to add a subtext to the story...

 

[Marco]

Good stuff Astrocyte. I hope you can add more.

One anomoly just occured to me. I suggested that the reduced mito content found in ME/CFS cases might be due to a switch from Type I to Type II muscle fibres as found in a previous ME/CFS study.

As Alex pointed out this study found no differences with controls in the proportions of muscle fibres and conclude the low mito content is due due deconditioning.

Strange, because a shift from Type I to Type II fibres is often associated with deconditioning and that possibility had to be controlled for in the previous paper that did find such a shift.