torsdag den 5. marts 2020

ME - a failure of inducing exercise tolerance?

ME hypothesis from Karolinska Institutet and Karolinska University Hospital in Sweden (1):

"ME - a failure of inducing disease tolerance upon chronic immune activation"

My question:
Is ME also a failure of inducing exercise tolerance?

At cellular level disease and inflammation result in increased reactive oxygen species (ROS) production. Stress-response pathways are countermeasures to ROS. Exercise also leads to increased ROS levels. The antioxidant enzyme superoxide dismutase 2 (SOD2) is one the primary mechanisms against ROS generated during exercise.

Quote from a review "Impact of oxidative stress on exercising skeletal muscle" (2):
"It is well established that muscle contractions during exercise lead to elevated levels of reactive oxygen species (ROS) in skeletal muscle. These highly reactive molecules have many deleterious effects, such as a reduction of force generation and increased muscle atrophy. Since the discovery of exercise-induced oxidative stress several decades ago, evidence has accumulated that ROS produced during exercise also have positive effects by influencing cellular processes that lead to increased expression of antioxidants. These molecules are particularly elevated in regularly exercising muscle to prevent the negative effects of ROS by neutralizing the free radicals. In addition, ROS also seem to be involved in the exercise-induced adaptation of the muscle phenotype.

Chronic oxidative stress is associated with an increase in protein loss and muscle atrophy. High ROS levels cause a sustained activation of NF-κB and of FoxO which then activate two muscle-specific E3 ubiquitin ligases, atrogin-1 or muscle atrophy F-box (MAFbx) and muscle RING (Really Interesting New Gene)-finger protein 1 (MuRF-1) [52]. MAFbx and MuRF-1 then degrade various proteins, such as titin, nebulin, troponin, myosin-binding protein C, myosin light chains 1 and 2 and myosin heavy chain [53,54]. Recently, it was demonstrated that excessive oxidative stress also enhances the transcription factor C/EBP homology protein (CHOP). This transcription factor also enhances expression of MuRF1, which again results in increased protein degradation [35]."

It seems like ME patients have increased muscle protein degradation:

Increased serum and urine 3-methylhistidine in ME patients

Increased plasma N,N,N-trimethyl-L-alanyl-L-proline betaine in ME patients

Proline, P5C and 4-hydroxyglutamate in ME

And do remember the transcription profile analysis of skeletal muscle from ME patients (3), quote:
"In an effort to establish which pathways might be involved in the onset and development of muscle symptoms, we used global transcriptome analysis to identify genes that were differentially expressed in the vastus lateralis muscle of female and male CFS patients. We found that the expression of genes that play key roles in mitochondrial function and oxidative balance, including superoxide dismutase 2, were altered, as were genes involved in energy production, muscular trophism and fiber phenotype determination. Importantly, the expression of a gene encoding a component of the nicotinic cholinergic receptor binding site was reduced, suggesting impaired neuromuscular transmission. We argue that these major biological processes could be involved in and/or responsible for the muscle symptoms of CFS."

Are the inflammatory reponse to disease and the adaptive response to exercise dysregulated in ME through the same pathways?


1) Lucie S.T. Rodriguez, Christian Pou, Tadepally Lakshmikanth, Jingdian Zhang, Constantin Habimana Mugabo, Jun Wang, Jaromir Mikes, Axel Olin, Yang Chen, Joanna Rorbach, Jan-Erik Juto, Tie Qiang Li, Per Julin, Petter Brodin: Achieving symptom relief in patients with Myalgic encephalomyelitis by targeting the neuro-immune interface and inducing disease tolerance

2) Peter Steinbacher, Peter Eckl:
Impact of Oxidative Stress on Exercising Skeletal Muscle

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