I have slept on it and have further criticisms, which are my personal opinion.
The first is the lack of empirical data, since the study relies on self reporting which can be subject to biases of the selves involved. This is no more scientific than a poll.
There is no attempt to measure cytokines in any of the subjects and yet cytokines are used as a basis for proposing a quantitative theory of sickness behaviour which equates high cytokines with high sickness behaviour without considering the complexity of the nervous system and the processes like sensitisation etc which are known to occur over time and in relation to molecular signals, or the complexity of cytokine networks. Specifically the work on identifying a cytokine profile for ME is IMHO inconclusive at this time (see their ref below*) and the issue of subtypes and cohort homogeneity has not been resolved and many cytokines are potentially implicated besides those involved in LPS reactions, but only one (
TGF-β) was found to recur in ME experiments and this was not a factor in LPS experiments or chronic pain. Different cytokines have different and specific effects so this is comparing apples with oranges and treating them all as if they were apples. I see no basis for a quantitative comparison across different conditions with different cytokine profiles. This is unsound and is not a basis for the hypothesis of
a dysregulated sickness behavior circuitry offered by the authors.
Interestingly one of the three refs for cytokine comparison is authored by none other than P.D. White an author of the PACE trial, which tells us something about the provenance of this kind of ideation. I find it hard to concentrate so would draw it to the attention of sharper eyes
@dave30th
https://www.researchgate.net/public...and_circulating_cytokines_A_systematic_review
*Chronic fatigue syndrome and circulating cytokines: A systematic review
Blundell S,
Ray KK,
Buckland M,
White PD.
Found -
The quality of the studies varied. 77 serum or plasma cytokines were measured without immune stimulation. Cases of CFS had significantly elevated concentrations of transforming growth factor-beta (TGF-β) in five out of eight (63%) studies. No other cytokines were present in abnormal concentrations in the majority of studies, although insufficient data were available for some cytokines. Following physical exercise there were no differences in circulating cytokine levels between cases and controls and exercise made no difference to already elevated TGF-β concentrations. The finding of elevated TGF-β concentration, at biologically relevant levels, needs further exploration, but circulating cytokines do not seem to explain the core characteristic of post-exertional fatigue.
two other key refs
https://docksci.com/endotoxin-induc...model-to-disent_5b0415eed64ab2fd1a34f190.html
Endotoxin-induced experimental systemic inflammation in humans: A model to disentangle immune-to-brain communication.
Manfred Schedlowski, Harald Engler, Jan-Sebastian Grigoleit
Found -
LPS induced .... increased expression and release of pro-inflammatory cytokines like IL-1beta, IL-6, and TNF-alpha.
https://www.ncbi.nlm.nih.gov/pubmed/17334668
Nitric oxide and pro-inflammatory cytokines correlate with pain intensity in chronic pain patients.
Koch A,
Zacharowski K,
Boehm O,
Stevens M,
Lipfert P,
von Giesen HJ,
Wolf A,
Freynhagen R.
Found -
IL-1beta, IL-2, IL-6, IFN-gamma, TNF-alpha in the plasma correlate with increasing pain intensity.
As you can read above the review of cytokine profiles for ME authored by PD White et al did not find results resembling the chronic pain and LPS induced profiles which at least share three cytokines,
IL-1beta,
IL-6, and
TNF-alpha. So this comparison of ME with chronic pain and LPS induction based on cytokine profiles has no basis in fact, by their own references.
I would also add that personally I consider the LPS protocol approaches the unethical. In my view it is not ethical to deliberately poison human beings and in any protocol like this there is a risk of hypersensitivity leading to anaphylactic shock. It must therefore be supervised by medical personnel and the administering of toxin contravenes the Hippocratic oath. I dont see how this can possibly be done ethically but again would defer to others who are experts in ethics and better qualified to judge than I.
I am therefore concerned about unethical attitudes towards human experimentation and also ignorant approaches to the study of ME being promoted by this work, no matter how heavy the disguise which superficial statistical analysis lends to this self reporting poll. The leap to assuming dysregulation instead of sensitisation is in my view indicative of projection which is a continuation of BPS errors.
I am making these points to explain why I say that this paper and related work do not have my confidence and I believe they and their authors deserve closer scrutiny on the basis that the price of fair treatment for ME patients is eternal vigilance.