"The most common peri-onset events reported by subjects were infection-related episodes (64%)"

The quote titling this post - "The most common peri-onset events reported by subjects were infection-related episodes (64%)" - comes from the (open-access) findings reported by Lily Chu and colleagues [1] continuing something of a research theme from this authorship group examining myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) (see here).

Indeed, it's probably no coincidence that the Chu cohort of "150 subjects fitting Fukuda 1994 CFS criteria" is the same as that used in their other research [2] when discussing another important issue: "post-exertional malaise in myalgic encephalomyelitis/ chronic fatigue syndrome."

On this most recent publishing occasion, Chu et al set out to: "Describe ME/CFS onset and course in one United States-based cohort." They did this via the use of "a detailed survey" that asked various questions about the first stages of participants' illness and what this eventually led to. The results obtained weren't exactly unexpected, but yet again stress how lots of things 'assumed' about ME/CFS really need to be properly verbalised in the peer-reviewed science literature (see here and see here for other examples). Of particular note in the Chu findings pertinent to inquiry on the 'course' of ME/CFS is this important snippet of information: "Based on available data, the median age of illness onset was 36.6 ± 12.3 years and median duration of illness was 12.5 ± 10.1 years." That's 'median duration of illness was 12.5± 10.1 years'.

Results: "The most common peri-onset events reported by subjects were infection-related episodes (64%), stressful incidents (39%), and exposure to environmental toxins (20%)." Infection or rather 'infection-related episodes' came out top of the pops with regards to possible onset events. I've said 'possible onset events' in that last sentence not to be belittle the first-hand reports obtained, but rather to emphasise how we're still in a bit of a 'not knowing' state when it comes to definite causative infective agents and ME/CFS onset. Yes, there is some quite strong evidence that infections caused as a result of Epstein–Barr virus (EBV) seem to be involved in some cases of ME/CFS (see here) but more often that not, people aren't screened for every possible viral or bacterial agent. At this point, I'd also hark back to the viral 'hit-and-run' hypothesis that has been talked about in some ME/CFS circles recently (see here and see here) and what this also means.

Onward: "For the overwhelming majority of patients (96%, n = 141), their illness did not improve with time although different patterns of illness were seen." That last sentence really speaks for itself in terms of what ME/CFS means in the long-term. That's not to say that symptoms did not 'fluctuate' - "59%, fluctuating (symptoms could change in severity but were always present)" - but participants on the whole did not 'shake off' their disability. And when it came to some details about how symptoms ebbed and flowed over the course of time, Chu et al have some data on that too: "Over time, flu-like symptoms, fatigue, unrefreshing sleep, and exertion-related items decreased the most, by between 12 and 25%... Cognitive symptoms present at the beginning of the illness tended to persist, declining by only 4–10%." Further focus on 'cognitive symptoms' is perhaps important [3].

Further: "Ninety-seven percent suffered from at least one other illness: anxiety (48%), depression (43%), fibromyalgia (39%), irritable bowel syndrome (38%), and migraine headaches (37%) were the most diagnosed conditions." The authors phrase this in the context that "patients with co-morbid medical or psychiatric conditions are the rule rather than the exception" when it comes to ME/CFS. But just before anyone starts making noises that anxiety and depression are so significantly present in this cohort and probably beyond, such findings does not open the door to any psychobabble 'biopsychosocial' (BPS) explanations about the cause/perpetuation of ME/CFS. I think many patients (and researchers) have had quite enough of all that (see here).

The Chu paper is a comprehensive one and adds to our knowledge about ME/CFS. It has its limitations - "reliance on subject self-report, recall bias, and relative superficiality of some survey items" - but no more or less than lots of other ME/CFS research. It hopefully will open the door to a lot more similar study; perhaps also including the odd biological measure also.

And just before you go, I'll draw your attention to the findings reported by Katherine Rowe [4] who also asked a cohort of participants with ME/CFS about their illness experiences. There's a few important matching details included in the paper - "Eighty percent reported a defined onset following an infection" - but also some other noteworthy information. One such observation was that: "Many indicated the need to be sensitive about when psychological assistance is offered... They were sensitive as to whether this was implying that psychological issues were the “cause.”." It's not difficult to see why patients with ME/CFS would think such [BPS] things.

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[1] Chu L. et al. Onset patterns and course of myalgic encephalomyelitis/ chronic fatigue syndrome. Front. Pediatr. 2019. Jan 16.

[2] Chu L. et al. Deconstructing post-exertional malaise in myalgic encephalomyelitis/ chronic fatigue syndrome: A patient-centered, cross-sectional survey. PLoS One. 2018;13(6):e0197811.

[3] Robinson LJ. et al. Impairments in cognitive performance in chronic fatigue syndrome are common, not related to co-morbid depression but do associate with autonomic dysfunction. PLoS One. 2019 Feb 5;14(2):e0210394.

[4] Rowe KS. Long Term Follow up of Young People With Chronic Fatigue Syndrome Attending a Pediatric Outpatient Service. Front Pediatr. 2019 Feb 21;7:21.

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"by the time ongoing fatigue was established, the immune activation was no longer present"

The quote heading this post - "by the time ongoing fatigue was established, the immune activation was no longer present" - comes from some media coverage of the paper published by Alice Russell and colleagues [1]. Said paper observed some interesting results in relation to the use of interferon-alpha (IFN-α) "used in the treatment of chronic Hepatitis C Virus (HCV) infection" and what this *could* mean in relation to a "proxy model of chronic fatigue syndrome."

The long-and-short of the Russell results and their possible application to chronic fatigue syndrome (CFS) is that for quite a few years now there have been rumblings that at least some cases of CFS (also known as myalgic encephalomyelitis, ME) might be *associated* with a viral hit-and-run encounter. By saying 'hit-and'run' I mean that an initial viral or bacterial infection is experienced which induces the symptoms of CFS. Said infection then eventually disappears for whatever reason(s) but leaves persisting symptoms such as long-term fatigue and more. Further explanation of this hypothesis can be seen in another of my posts on CFS (see here).

So: "Fifty-five patients undergoing IFN-α treatment for chronic HCV were assessed at baseline, during the 6–12 months of IFN-α treatment, and at six-months post-treatment." The use of IFN-α is clinically indicated for HCV infection as part of an antiviral therapeutic regime ("IFN-α and ribavirin"). Various biological parameters were assessed in the 55 participants as well as in separate groups of those diagnosed with CFS and so-called "healthy volunteers."

Treatment with IFN-α induced fatigue in quite a few of those being treated for HCV infection. Most cases of fatigue resolved at 6-months post-treatment but for some, fatigue remained and for about 30%, levels of fatigue were "higher six-months post-treatment than at baseline." The authors looked at the biological results obtained for those with 'persistent fatigue' (PF) and compared them with those with 'resolved fatigue' (RF) to see if they could discern some differences.

They came up with a few important group observations: "Subjects who later develop PF have higher fatigue in response to IFN-α", "Subjects who later develop PF have higher IL-10 levels before treatment, and IL-6 and IL-10 levels in response to IFN-α", and "Psychosocial and clinical risk factors do not distinguish PF from RF subjects." What this all amounts to is that within quite a small participant group: "findings from this study support the hypothesis that abnormal immune mechanisms are important in CFS, but only early in the course of the illness, around the time of the trigger, rather than when the syndrome is established." Further the study: "confirms the importance of the acute fatigue response to the trigger, rather than of the recovery period preceding the illness."

There is more to do in this area bearing in mind that CFS is a pretty heterogeneous condition both in terms of symptom onset and the course of the illness. Researchers also admit that they "can only speculate at this stage on whether or not the mechanisms underlying the persistence of fatigue in CFS and IFN-α induced PF are related" and their suggestion of a proxy model. Others who have covered this study have said similar things (see here). This is also important given other results reported by the authors on those diagnosed with CFS compared with those 'healthy' controls/volunteers.

Still, there are some interesting observations made by Russell et al and once again, such results hopefully move CFS further away from the biopsychosocial (BPS) model of old that has seemingly done considerable damage to those diagnosed (see here and see here). Indeed, such post-infective thinking kinda brings CFS back full circle...

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[1] Russell A. et al. Persistent fatigue induced by interferon-alpha: a novel, inflammation-based, proxy model of chronic fatigue syndrome. Psychoneuroendocrinology. 2018 Dec 17.

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"a 256-peptide immunosignature with the ability to separate ME/CFS cases from controls"

The findings reported by Oliver Günther and colleagues [1] (open-access available here) really interested me. They interested me because they talked about the "hit and run" hypothesis being pertinent to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), where "a pathogen or other immunological insult experienced by a subject may be gone, but leaves behind physiological disequilibrium." They interested me because researchers turned to "an immunosignature assay (ISA) that employs a microarray of thousands of random-sequence peptides to interrogate antibodies in a broad and unbiased fashion" to try and pick out the biological effects of the 'hit and run' hypothesis in relation to ME/CFS. And they interested me because researchers reported that they were able to identify "a 256-peptide signature that separates ME/CFS samples from healthy controls, suggesting that the hit-and-run hypothesis of immune dysfunction merits further investigation." Lots of interesting things (honest!).

The Günther paper is open-access so doesn't really need too grand an explanation from me. The long-and-short of it was that following the adoption of a discovery and validation methodology (an increasingly favoured option in ME/CFS research circles), authors came up with a sort of 'biological fingerprint' "optimally separating ME/CFS cases and controls" based on the examination of serum samples. They also noted that in amongst their 256-peptide signature, one particular peptide - "LRVVWLSGVASG" - was also mentioned in another independent study with similar aims [2] perhaps therefore requiring further research focus. For those who might not be totally au fait with peptide designation, that string of letters is not meant to be pronounced, but rather each letter corresponds to an amino acid making up that particular peptide.

Whilst this is great work and indeed, represents some really quite detailed analysis, the authors caution that the science is not quite there yet when it comes to a 'biological test' for ME/CFS. So: "the heterogenous nature of ME/CFS clinical presentation and the variance natural present amongst control samples means that group labels in the Discovery and Validation Sets are not based on any gold standard." Diagnosis of ME/CFS still remains a point of real contention in various circles (see here) given the variety of diagnostic criteria available. Indeed, some commentators have suggested that the combination of 'ME/CFS' as a unified diagnostic label simply cannot ever exist (see here). The authors further note that: "Even the best research case definitions are often subjective and—in the absence of clear biomarkers—any group of ME/CFS cases likely comprise a heterogeneous set of pathologies."

I'm also minded to suggest that as per the lessons being learned in connection to autism biomarker research for example (see here), one needs to perhaps think about getting different research groups together who are looking at ME/CFS from different angles (see here). Y'know, sort of combining various different biomarker studies looking at various different biological 'angles' and sorta meta-analysing all the collected data to see if a larger, grander, range of variables might provide a more accurate biomarker picture of the condition(s)...

Still, the Günther study represents some good science and good value-for-research-money. It stresses how, by utilising the pretty sophisticated analytical equipment available these days, one can start creeping ever closer to some of the possible biochemistry that underpins ME/CFS (or at least some ME/CFS) and perhaps then also start some conversations centred on what can be done to alleviate symptoms and cure such a devastating illness.

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[1] Günther OP. et al. Immunosignature Analysis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Mol Neurobiol. 2018 Oct 8.

[2] Singh S. et al. Humoral Immunity Profiling of Subjects with Myalgic Encephalomyelitis Using a Random Peptide Microarray Differentiates Cases from Controls with High Specificity and Sensitivity. Mol Neurobiol. 2018 Jan;55(1):633-641.

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