Several recent observations have revealed possible routes of physiological consequences of toxicant exposure (ie ozone) that may be related to symptoms of MCS. It has been suggested activation of TRP channels may play an important role causal in MCS. (Pall) Bessac and Jordt write, "that both the TRPA1 and TRPV1 receptor may contribute to chemical hypersensitivity, chronic cough, and airway inflammation in asthma, COPD, and reactive airway dysfunction syndrome" and other reports link TRPA1 to asthma.(Drug Disovery) Activations of these receptors will increase their expression, therefore, increasing the likelihood of activation (and symptoms) by exposures that activate them. Or on the other hand, Bessac writes, cross-desensitization exists by one chemical may desensitize it to another. As we noted over a year ago, changes in these receptors can occur by interactions with other proteins including IGF-1 and inflammatory cytokines that may alter these receptors functioning which may cause "aberrant signaling".
Recently it has been demonstrated that ozone activates TRPA1 channels and TRPA1 channels have been shown to be upregulated by the inflammatory cytokine MCP-1/ pathway which has been discussed at length in other blogs. Ozone and smoking promote a process called oxidation of phospholipids (oxPL) that generates ROS from NADPH oxidase activation, increase MCP-1, negatively regulate Nrf2 and are associated with autoimmune diseases such as lupus, RA and Parkinson's disease. OxPL are generated during inflammatory conditions and inhibit the full differention of dendritic cells and therefore restrict normal adaptive immune response. (Bluml) Recently other research has provided evidence that additional ozone reactions can be caused from abnormal enzymatic actions of glutathione which, by he way, is also regulated by Nrf2 through other proteins. In addition, ozone contributes to airway hypersensitivity and hyperresponsiveness through the modulation of TLR receptors and other green house gases may play a part in the "learned response" tied possibly to physiological response in MCS, may potentiate the effects of lead-based paint and increase related health risks and cause panic-like behavior.
Just in case you have heard that ozone generators are physiologically calming...well, according to the research, quite the opposite seems to be true. For instance, as new study shows there is a sensor in the brain for CO2, another greenhouse gas, that will cause panic-attacks. Such behaviors are crucial for animals for survival to be able to "sense" and prevent biological suffocation and "aberrant signaling" of TLR receptor may decrease the threshold of activation of these sensors. Keely explains that "epithelial hypoxia" in the gut results in a 40-fold increase in translocation of gram-negative bacteria, regardless of intestinal barriar function. In the gut, hypoxia is associated with acute and chronic inflammation (ie IBD) and its presence initiates factors that exploits the intestinal environment to achieve the translocation process. One can assume that similar sensory processes that activate panic or flight response may be present in other tissues including the lungs and gut. Additionally, it has been demonstrated that viruses activate TLR receptors but the mechanism is slightly different.
TLR4 receptors recognize LPS endotoxin which is the a component of the wall of gram-negative bacteria. Several reports now suggest that a route of CFS is endotoxin exposure.Endotoxin is the result of lysis of bacteria from immune cells and therefore, will be present whereever there is inflammation. Of course, minimizing exposures that contain bacteria is one way to reduce TLR signaling. There are other TLR receptors that also initiate immune responses to other contaminants. Recent evidence has demonstrated that saturated fat "angers" the immune system by interacting with TLR4 but the exact process of how saturated fat does this is unclear. Cani has noted that LPS in high-fat diets is 2 to 3 times greater and that LPS-containing proportion is greater in the high-fat diet gut. Other conditions may favor altered TLR4 signaling and because they initiate a variety of events inside the cell, the absence or dysregulation of the antioxidant system can lead to an exacerbation of inflammatory events because it modulates cytokines production such as pro-inflammatory Il-1 and Tnf-a and the anti-inflammatory cytokine Il-10 which modulates sickness syndrome. The antioxidant system Nrf2 supports other proteins in mitochondrial biogenesis which it has been reported that exposure to chemicals has an effect on cellular respiration and alters mitochondrial function. Altered TLR signaling also may contribute to neuropathic pain. Other effects include alteration in neurotransmission such as dopamine which may contribute to Parkinson's disease and other neurodegenerative diseases.
I have written several essays on TLR receptors and how they interact with the immmune system from different environmental toxicants which can be read here. Also, to read citations for this article click here.
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