In the last few years, environmental illness researchers have suggested that chemical sensitivity is related to a general loss of tolerance that may occur after an event such as bacterial or viral event. Of course, this would make sense given that an inflammatory event may lead to loss of tolerance through alterations in immune function and some experts believe a similar process is responsible for autoimmune-type reactions and a loss of T regulatory cells (Tregs). In general, Treg serve as a type of mediator for inflammatory conditions and modulates the type and severity of the immune reaction. In MCS, there is a loss of tolerance to chemicals in the environment at levels that normally do not effect a healthy individual. Interestingly, a recent study of asthma has shown that hypersensitivity airway responsiveness can be improved by boosting immunity in the gut. The fact that airway responsiveness can be improved through gut improvement helps to support the possibility that MCS immune dysfunction may begin in the intestinal tract or the lungs even though symptoms may not necessarily be respiratory or gut related. It has been known for two decades, the intestinal tract is an important regulator of immune and brain function but admittedly, little is known about the pathways or the process involved that makes the connections of the intestinal tract, the brain and the CNS. However, studies published last year identified inflammatory brain processes that effect gene regulation and neurotransmission can be the result of the activities of inflammatory mediators or cytokines in the gut and the liver.
Individuals with MCS often present with abnormal respiratory function and many that suffer from MCS propose they are more sensitive to carbon monoxide and hydrogen sulfide than others. I would suggest through observation this is also true of nitrous oxide and possibly other greenhouse gases and note here there have been reports of mood and behavior changes from exposures to higher levels of these gases. These reports are similar to many with MCS when they describe their reported reactive symptoms. Therefore these reactions could be the result from elevations in greenhouse gases in addition to other pollutants that combine to form explained additional "triggers". Previously, I have suggested the loss of Nrf2 and its associated proteins such as HO-1 that regulate the gasotransmitters may be to blame and could lead to loss of tolerance or heightened reaction even to lower levels of "perceived" pollutants or chemicals in the environment. Considering the levels of greenhouse gases are steadily increasing on the average in the environment with each decade-- the constant exposure to one may be reducing the tolerance to the cumulative total of the others or "potentiating" the effects. This brings to light an important health and policy concern since the "jury" is still out on how to reduce greenhouse gases with our present dependance on fossil fuels. Interestingly, you never really hear about the increases in greenhouse gases in relation to the causes and implications of MCS, even though it should be considered...
In any case, there is recent evidence the proteins that make up the xenobiotic detoxification system such as the Nrf2, AhR, and HO-1 may influence Treg regulation. For this reason, the effects of Treg deficiency and dysfunction should be considered why addressing the possible causes for increased sensitivities that are observed in those effected with environmental illness and why boosting gut immunity of systemic immunity may influence more than one organ system. In addition, it has been demonstrated that endotoxin a component of bacteria may lead to a heightened response from allergans. It could be endotoxic exposure leads to a heightened response to chemicals or contaminants whether endogenous or not and alterations in methylation from endotoxin may augment conditions of the "loss of tolerance" that that lead to and occur with environmental illness. Unfortunately, this "loss of tolerance" may also be the consequence of pathogens and contaminants that normally reside at low levels in different tissue and are present in the environment.
Strickland, D. H., Judd, S., Thomas, J. A., Larcombe, A. N., Sly, P. D., and Holt, P. G. (2010). Boosting airway t-regulatory cells by gastrointestinal stimulation as a strategy for asthma control. Mucosal immunology. http://www.citeulike.org/user/HEIRS/article/7560150
Chapman, J. T., Otterbein, L. E., Elias, J. A., and Choi, A. M. K. (2001). Carbon monoxide attenuates aeroallergen-induced inflammation in mice. Am J Physiol Lung Cell Mol Physiol, 281(1):L209-216. http://www.citeulike.org/user/HEIRS/article/7560177
Zhou, X., Kong, N., Zou, H., Brand, D., Li, X., Liu, Z., and Zheng, S. G. G. (2010). Therapeutic potential of tgf-beta-induced cd4(+) foxp3(+) regulatory t cells in autoimmune diseases. Autoimmunity. http://www.citeulike.org/user/HEIRS/article/7560254
Fousteri, G., Dave, A., Bot, A., Juntti, T., Omid, S., and von Herrath, M. (2010). Subcutaneous insulin b:9-23/ifa immunisation induces tregs that control late-stage prediabetes in nod mice through il-10 and ifngamma. Diabetologia, 53(9):1958-1970. http://www.citeulike.org/user/HEIRS/article/7299083
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