T Regulatory Cells and Vitamin D - Their Importance to Environmental Illness Including Chemical Sensitivity.

Over the past several months there has been a number of studies that shed light on the activities of a subset of immune cells called regulatory T-cells. Interestingly, these new findings may result in answering some important questions related to multiple chemical sensitivity which is a condition where patients become sensitive to agents normally found in the environment and these agents can be "natural" or manmade. Every MCS patient is different but their symptoms may include nausea, vertigo, brain fog, light sensitivity and others. Generally, reactions occur when MCS patients are exposed to concentrations of noxious stimulants, chemical agents or irritants that would not normally elicit a reaction in those without MCS. While there are many theories out there about what causes MCS, so far there are few that actually come close to understanding MCS and other facets of environmental illness. Unfortunately, many health experts are critical about the existence of MCS and try to classify it as a "psychomatic condition" while others are more open-minded and have begun to rally and now treat multiple chemical sensitivity as a "real" medical condition.

One MCS theory that is gaining in popularity and research support is that MCS is a condition that may be caused from a loss of tolerance and is similar in nature to inflammatory diseases that are commonly classified as autoimmune diseases. In this realm, there is no doubt that MCS could fit and recent studies provide more evidence that this could be the case. As we have noted all along several biological sub-systems, for lack of a better word, may play a part in the development of MCS and this kind of loss of tolerance or loss of homeostasis. The most recent findings support our belief that the development of MCS can be dependant on the dysregulation of Nrf2 which regulates a number of antioxidant proteins including HO-1 and NRF1 which is important for mitochondrial biogenesis. Over the past two years, we have discussed the function of this antioxidant system in modulating inflammatory cytokines. Also, important findings of vitamin D show it may be an important regulator and for MCS, it may be an important as a MCS therapy. Mainly because vitamin D can regulate regulatory Tcells and reduce autoimmune Th1 responses in association with Il-10. In the past several years a number of studies have shown that members in general population are deficient in vitamin D and supplementation of vitamin D reduces the incidence of several autoimmune conditions including MS, rheumatoid arthritis and inflammatory bowel disease. Deficiencies in vitamin D also is associated with metabolic sydrome and "itch". The latter being a common symptom in a number of autoimmune conditions as well as, multiple chemical sensitivity.

Late last year an interesting study was published that provides a little more insight on how regulatory T-cells (Tregs) may influence MCS and other environmental diseases including cancer. As the author notes in the abstract, air pollution is an important contributor to the development of environmental disease including asthma, allergy and multiple chemical sensitivity. Often the former two are co-morbid in MCS patients but not always and as Micovic explains, the assault by environmental insults including VOC results in an "abnormal immune response of lymphocytic subsets." Normally, the body is able to decipher the good and bad stimuli and develop a tolerance to those that are less noxious. Recent research findings support this process is achieved through the activities of Tregs and so is the "loss of tolerance". Interestingly, this researcher found in his experiments that normal chronic exposure to an air pollutant, increases the percentage of Il-10-dependant Tregs. On the other hand, a loss of tolerance may mean a reduction of Tregs or one of its associated proteins. In scientific studies, the destruction of Treg populations cause mice to spontaneously develop a "spectrum of autoimmune disease" (Micovic) and others displayed anaphylactic-type responses. Park clarifies how production of CD4+CD25 by Il-10 production provides a protective role against lung hypersensitivity, again, to chronic exposure to environmental antigens. Activation of nociceptors has also been implicated as a factor in MCS. (Pall) It was recently demonstrated that in a mouse model of autoimmune encephalitis, TRPV1 signaling is important in modulation of IL-10 and inhibition of TNF-a and Il-1b and subsequent increases of IL-17. (Tsuji) This explains why the TRPV1 receptor has become the focus in the development of therapeutic approaches to diabetes.

Cong describes in his paper that Tregs are believed to be "central to the prevention of autoimmune and inflammatory disorders and there are many types of these regulatory immune cells that exist including CD4+CD25+, Tr1, Tr3 and vitamin D-dexamethasone induced Il-10. Notably, we are talking about only a very small number of T cells in relation to the total number of immune cells. Therefore, unless highly specialized equipment and lab techniques are used an adequate representation of this kind of CD profile is virtually non-existent or available to the typical clinical physician. If you have read some of our blogs in the past, we discuss IL-10 quite extensively in relation to Il-10 as a modulator of the severity of sickness syndrome. Sickness syndrome is marked by a variety of symptoms including changes in appetite, mood, fatigue levels, neurotransmitters, etc that ultimately result in obvious behavioral changes and usually is considered a part of "sickness" and accompanies increases in cytokine production including Il-1 and Il-6. Sickness syndrome is not exclusive of humans and has been observed in animals. In addition, Il-10 has been shown to regulate Il-17 which is a cytokine normally associated with autoimmune-type disease and deficiencies in IL-10 correlate well to increases in fatigue and other sickness type behaviors which are characteristic of many environmental illnesses. One study shows that infection-induced inflammatory mediators including NO and TNF-a by GSK-3b, which is the off-switch for Nrf2, is achieved by inhibiting Il-10. Parkinson's diseases is considered an environmental illness and alteractions in the expression of the antioxidant HO-1 and GSK-3b increases the risk for its development. (Infante)

It is now recognized that Tregs interact with one another and in a study of asthma, the loss of IL-10 fails to "induce tolerance". Also, George demonstrates that suppression of autoimmune-type inflammatory conditions by Treg CD4+CD25+ is dependant on HO-1 often regulated through Nrf2. Rockwell recently discovered that the inflammatory cytokines Il-17 and IFN-gamma in systemic lupus, an autoimmune disease, are regulated by Nrf2 in CD4+ cells. It also regulates IFN-gamma in Th1 cells. Taking this information into account, this supports the HEIRS hypothesis that the dysfunction of the Nrf2 pathway either because of genetics or other environmental factors such as malnutrition may be critical to the development of MCS, in addition to, other environmental diseases.

Recent studies have also determined that age and mental stress can decrease the levels of Tregs and therefore, this may explain why mental stress exacerbates MCS and other environmentally-induced and autoimmune diseases. (Freier) One author suggests that in the gut, Tregs work commensally with gut bacteria to prevent intestinal inflammation and reduces expression of Il-17 implicated in carcinogensis and disregulation of this system may increase the incidence of colon cancer and may play a role in other cancers as well. (Erdman) We have suggested that the aryl hydrocarbon may contribute to symptoms of MCS and indeed, some some ligands and not others interfere with Treg expression and increase Il-17. (Quintana) To make matters more complex, the presence or absence of TLR signaling (which we have discussed exhaustively in the past) in a Il-10 -/- environment may increase the likelihood of the loss of suppression of autoimmune-type complications and lead to a "loss of tolerance" with "inocuos" pathogens such as bacteria that normally reside in the ihuman tissue such as the human gut. (Gonzales-Navajas) Notably, the relationship of Tregs, Il-10 and other factors such as GSK-3b provide an explanation of why Nrf2 activators (EGCG), vitamin D, probiotics that modulate intestinal immunity have demonstrated they reduce or alter response of inflammation, oxidative stress, and aid in the reduction of symptoms to noxious agents and have been shown to reduce the incidence of diseases including cancer and boost innate immunity. Drops in Tregs have been observed in patients with CFS (although studies conflict) and others show an abnormal immune phenotype and production of inflammatory cytokines associated with the illness is consistent with our premise that symptoms in CFS may be caused by sickness syndrome. Consequently, alterations of I-10 dependant tregs provides a mechanism for the increase risk for cancer in environmental illnesses such as CFS. It is worth mentioning that when dysregulation of the Nrf2 pathway occurs any number of aberrations in profiles may appear because the pathway controls so many different efflux proteins, transporters and enzymes. Of course, the initial trigger of illness and a patient's genetics may also lead to differences in lab profiles and explain why such a wide range of stimuli including endotoxin, perfumes, odors, oils, foods, terpenes, etc may initiate a response in MCS patients.




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