sickness syndrome even though CFS and sickness syndrome are not the same thing. Sickness syndrome is a variety of changes that occur in the body as a response to sickness and provides a mechanism to fight whatever is causing the sickness. Personally, I can recognize it more in animals because humans have been taught that we "must" overcome --- and that goes for being ill too that usually leads to more sickness.
Michael Maes has probably been the leader in the idea of sickness syndrome in relation to CFS. In his last report, he definitely makes the distinction and I have to agree with him. CFS is not sickness syndrome and is more due to inflammation and oxidative and nitrosative stress and pathogenic conditions and permeability can be to blame. Again, I agree and am critical of some that try to base everything about CFS on oxidative stress because it does not really explain how one "gets there"! In my view, it all comes down to and the problem with labels and this always has been my issue..... IN this case, how can we understand where one illness like CFS starts and another one ends such as sickness syndrome if noone really has defined the former CFS well in the first place? It is my belief that sickness syndrome may be a prelude to CFS or maybe the beginning point of it, and different factors can inhibit or lead to a "full-blown" case of CFS and recognizing the biological factors that play a part may in fact, help to prevent CFS in its most severe form. As far as oxidative and nitrosative stress in CFS, I think if you just leave it at..then it is doing a disservice not only to the condition but to those who suffer from it. The reason I say this is because of the nature of oxidative/nitrosative stress --- it is a natural result of cellular processes. Just saying that CFS is caused from too much of these stresses does nothing to answer what is causing the overwhelming oxidative stress in the first place in CFS. Maes has implied that endotoxin may be a pathway to CFS and bacterial infection has potential for causing oxidative stress and changing environments and altered methylation. But the possibility that other environmental factors such as hyperglycemia and high-fat diets which promote bacterial translocation and consequently activate certain immune responses leadin to CFS also, can not be dismissed. I have suggested that the failure of the antioxidant system to adequately meet the needs of oxidative stress or maybe even at all to any real level may play a very important role. In other blogs, we have noted that oxidative and nitrosative stress is needed to activate this system and nutritional and genetic factors may influence the speed and level of activation. So if we have overwhelming oxidative stress -- it makes sense that something like underactivation of the antioxidant system may be at fault or is just not working. So in essence, it should be a no-brainer to look at the Nrf2-Keap1 and other proteins it controls to get a better handle on what may be causing the failure of an adaptive immune response and elevations in inflammatory markers and oxidative stress that are obviously maladaptive.
Several new studies some evidence that a failure in the antioxidant system could contribute to CFS. It is not a direct road I admit, but considering I have been following these paths for 3 years now. They make sense to me, mainly because I look for the CFS from a more holistic and systems theory perspective. For someone that has been trained both in anthropology and biology, this perspective works better for me when I need to find out the answers to different questions that need to be investigated. In addition, one could ask what is a direct road or pathway in reference to disease anyway....to me, it is all relative and most always depends on personal interpretation. Several months ago, I blogged that environmental pollutants may contribute to diabetes and insulin resistance. Since then several other reports conclude this may be the case and many studies have provided evidence how inflammation can lead to insulin resistance and diabetes through the down-regulation of genes and up-regulation of inflammatory cytokines. Several inflammatory markers, not just one, can contribute and can be produced as a consequence of the stress response including TNF-a, Il-1, Il-6. Some of these activate other responses that lead to neuroinflammation and also alteration of neurotransmitters and have other effects on brain chemistry which could be characteristic of the cognitive dysfunction associated with CFS.
It has been suspected that pollutants lead to the alteration of a class of class of genes. I refer to them most often as PARRs and may include PPAR-gamma, PARR-delta and PARR-alpha. I have discussed both PPAR-gamma and PPAR-alpha at length in different discussions and most notably, PPAR-gamma is an important anti-inflammatory which helps prevent the development of insulin resistance in addition to other functions and may help repress autoimmunity. (Klotz) Recently, a study of the combination of pioglitizone and caffeic acid, demonstrated significant improvement in a mouse model of chronic fatigue. In this study, the results showed improvements in running wheel activity, locomotor activity and anxiety. Other improvements included reductions in oxidative damage including lipid peroxidation and nitrite concentration and increased glutatione and catalase levels in addition to altering mitochondrial function. When one digs a little deeper, interesting things appear related to the actions of these compounds. Caffeic acid is an antioxidant and anti-inflammatory that while having potential hazard qualities, also demonstrates the ability to " suppress MMP-9 enzyme activity and down-regulate NF-κB through inhibition of protein IKK and activation of Nrf2 (Lee) and other studies provide in vitro evidence it may effect DNA methylation.(Wipedia)" In contrast, pioglitizone is an anti-hyperglycemic medication and "stimulates the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ) and to a lesser extent PPAR-α. Both of these compounds act through PARR-gamma directly or indirectly via Nrf which may explain why their benefits in the CFS model is synergistic compared to when they were used alone. (Kumar) Generally, PARRs modulates the transcription of the insulin-sensitive genes involved in the control of glucose and lipid metabolism in the muscle, adipose tissue, and the liver. (Wipedia)" What this says to me is that CFS very well could be considered a condition that is a consequence of significantly disrupted normal glucose uptake and cellular and energy metabolism and altered immune function in different tissues.
I have also postulated that the aryl hydrocarbon may play an important role in both CFS and MCS and there are several "conditions" that lead me to make this assumption and the hypothesis but unfortunately, how this interaction occurs is quite "muddy". First, it has been demonstrated that there is a close connection in the actions of the AhR and the Nrf2 in response to environmental pollutants and their "gene batteries". Second, I have suggested that abnormal signalling from the AhR may influence the functioning of several proteins including the Nrf2 even though the specific mechanismin of how this is achieved is not entirely understood. Third, dioxin which persists in the environment, albeit at lower levels in the last decade in many locales but still present in food, has been associated with diabetes and activates the AhR. Four, for some time it has been believed the AhR may inhibit PPAR-gamma and therefore leads us to environmental conditions, at least physiologically, of elevated inflammation and an increased risk for diabetes. (Remillard) Arguably, the role of the AhR on PPAR-gamma depends on the tissue. (Kitchner, Shin) However, dioxins are bioaccumulative and activation of the AhR and its effects on PPAR-gamma may spill over to surrounding tissues. Lastly, a new study has shown that Nrf2 drives PPAR-gamma in protecting against oxidant injury at least in the respiratory system. Taking all this into account, it is safe to at least suggest that CFS may be influenced by fluctuations in PPAR-gamma and the proteins that regulate it and factors that upregulate it may be beneficial or preventative against CFS. Because PPAR-gamma demonstrates inhibitory properties on autoimmune responses, its absence may play significantly in the "loss of tolerance" responses of chemical sensitivity and inflammatory bowel disease. Other studies show PPAR-gamma has as an important regulatory function with HO-1 and may be neuroprotective against Parkinson's (Lui, Schintu) and influences mitochondrial biogenesis through PGC-1a (Miglio). In other blogs, I discuss how certain nutritional compounds such as resveratrol and EGCG in different foods have shown some benefit and their modes of actions address some of the issues that are discussed in the paragraphs above. IN addition, because these proteins can be effected by methylation this explains the inheritabilty factor that exists with CFS that is not explained just by the presence of oxidative stress.
Notes:
- Endotoxin is considered potential pathway to CFS and inhibits PPAR-gamma through Tnf-a (Zhou)
- It as been suggested that XMRV may play a role in CFS - I would suggest that while XMRV may be a piggy-back condition, any pathogen or infection or pollutant that inhibits PPARs and increase inflammatory mediators contribute to CFS.
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