Complement activation in a model of chronic fatigue syndrome, 2003, Sorensen et al

Hutan

Hutan

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Published in 2003

https://www.jacionline.org/article/S0091-6749(03)01546-X/fulltext

Abstract
Background: A need exists to identify biological markers in chronic fatigue syndrome (CFS).

Objective: To use an exercise and/or allergen challenge to induce the symptoms of CFS and to identify a biological marker that correlates with these symptoms.

Methods: Patients with CFS (n = 32) and age-matched, normal control patients (n = 29) exercised for 20 minutes on a stationary bike at 70% of their predicted max work load (Watts). Patients from each group with positive skin test results were also challenged with intranasally administered relevant allergens. Symptoms were recorded for 2 weeks before and 1 week after each challenge, using 3 different instruments. Blood samples were taken before, and 0, 1, 6, and 24 hours after challenges. Levels of complement split products, cell-associated cytokines, and eosinophilic cationic protein were measured. Mean preexercise and postexercise symptom scores were evaluated for each group.

Results: Exercise challenge induced significant increases of the complement split product C4a, but not C3a or C5a, at 6 hours after exercise only in the CFS group (P < .01), regardless of allergy status. Mean symptom scores were significantly increased after exercise through the use of a daily diary (P < .03) and a weekly diary (P < .01) for the CFS group only. Mean scores for the Multidimensional Fatigue Inventory categories “reduced activity” and “mental fatigue” were significantly increased in the CFS group only (P < .04 and P < .02, respectively).

Conclusions:Exercise challenge may be a valuable tool in the development of diagnostic criteria and tests for CFS. Establishment of a role for complement activation products as markers or participants in production of illness require further study. (J Allergy Clin Immunol 2003;112:397-403.)
 
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Okay, this may win stupid post of the day award but as that doesn't usually stop me....

Are we making a big assumption here that there is a relationship between what happens when exposed to an allergen a person is sensitive to and the underlying pathology of ME?

Admittedly if you have ME and are exposed to a trigger then the allergic reaction will most likely affect the ME but that doesn't mean they both have the same underlying mechanisms.

also
Objective: To use an exercise and/or allergen challenge to induce the symptoms of CFS and to identify a biological marker that correlates with these symptoms.
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Seems to imply participants were fairly symptom free unless exposed to a trigger which would make their ME very mild indeed. I think most mildly affected patients probably spend a lot of time in PEM and so usually aren't symtom free.
 
Invisible Woman said:
Admittedly if you have ME and are exposed to a trigger then the allergic reaction will most likely affect the ME but that doesn't mean they both have the same underlying mechanisms.
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I have a couple of type I allergies (Timothy grass pollen and what is probably fungal spores) but neither affects my ME symptoms. I think that for some people, type I allergic reactions might indirectly worsen ME symptoms, possibly through extra cytokines or depletion of resources or some such thing.
 
Keela Too said:
I wonder how MS patients, post-chemo patients, or others with health complications would compare?
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paper said:
The exacerbation of symptoms after exercise is seen only in the CFS population. Exercise does not appear to exacerbate symptoms in other disease states associated with fatigue such as depression or autoimmune diseases including rheumatoid arthritis, systemic lupus erthymatosus, and multiple sclerosis. In fact, depressed persons usually report a relief of symptoms after exercise. 23, 24, 25, 26 Patients with rheumatoid arthritis tolerate moderate exercise as part of treatment without an exacerbation of clinical markers, immune markers, pain, or disease activity. 27, 28 Additionally, exercise intervention in patients with lupus and multiple sclerosis does not significantly increase fatigue 29 and in some cases reduces fatigue. 30, 31, 32
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Question: So they found a correlation between an increase of C4a at 6 hours and an increase in symptoms the day after the exercise challenge. But the C4a at 24 hours was back down to pre-challenge level so it can't be directly responsible for the increased symptom then. What is missing here? There must be something else that continues to increase, or get otherwise dysregulated, well beyond 6 hours.

Interestingly I always get a minor symptom flare 4 hours post exertion (this study only measured at 1 and 6 hours). This flare involves a limited set of symptoms, the ones typically associated with coming down with a bug like increased sore throat, getting a bit hot & cold shivery, etc. These actually improve again over a few hours which would fit with the temporal pattern found in this study. But it doesn't explain my main PEM flare the next day (or later for some people).
 
Ravn said:
Question: So they found a correlation between an increase of C4a at 6 hours and an increase in symptoms the day after the exercise challenge. But the C4a at 24 hours was back down to pre-challenge level so it can't be directly responsible for the increased symptom then.
Click to expand...

Revisiting this study in the context of a non-negligeable amount of recent research finding complement abnormalities in people Long COVID has my peaked my interest.
 
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