Scientists from Harvard Teaching Medical Hospital have discovered that Mitochondria respond to trauma by creating patient inflammation and a response not unlike bacterial infection. Best known as the energy producing powerhouses of the cell (being home of the Citric Acid Cycle and oxidative phosphorylation), Mitochondria have long been recognized as ancient symbiots – not originally part of the eukaryotic cell line, but were once prokaryotes that have, through a selectively advantageous symbiotic relationship, become incorporated into the eukaryotic cell line. These organelles have their own genetic code, their own DNA, their own plasma membrane, and are able to reproduce independently of the cell. Now, this newly understood behavior may shed light onto their ancient bacterial origin.
Beth Israel scientists have shown that during respiration, molecules from spent or disrupted mitochondria escape the cell and enter the bloodstream causing an immune response with an evolutionarily conserved similarity to bacterial infection. The study suggests that during times of severe injury when the body is undergoing rapid metabolism in response to the damage, this process is elevated and thus allows larger concentrations of the spent mitochondrial DNA to induce a cascading response in the patient. These circulating mitochondrial protein signatures ultimately cause the body to respond as though a bacterial infection were running rampant. This immune response leads to a syndrome known as Systemic Inflammatory Response Syndrome (SIRS) that can be very dangerous leading to a racing heart, fever, breathing difficulties, and eventual organ failure.
It’s interesting to think that the body contains self-destructive mechanisms like this. However problematic these by-products may be, they are definite parts of mitochondrial energy production and therefore a requirement for life as we know.
Recent discovery of a food allergy candidate gene on chromosome 5q22.1
Allergies are a broad category of disorders that all have one common trait, immune reactions to normally non-harmful substances. They are chronic diseases (ranked 5th on the list among chronic diseases in the US) that can dramatically degrade the lifestyle of those affected depending on the degree of severity. About 55% of the population has an allergic response to one or more allergens. However, some of the most dangerous forms of allergies are food allergies. Just imagine your body reacting negatively to the fruit, meat, nuts, or dairy products that are normally needed for survival. Just imagine not being able to eat at the restaurant you love because you are scared of what ingredients they use. These disorders can be more than physically harmful, but psychologically detrimental to the carrier as he or she becomes afraid of that which is need to sustain life.
However, advances in allergy research are being released almost daily. In an article published in Nature Genetics, scientists have discovered a candidate gene associated with the condition known as eosiniophilic esophagitis (EoE) – an inflammatory response to food allergens that leads to rapid buildup of eosinophils in the tissue of the esophagus eventually leading to dysphagia (difficultly swallowing). The candidate gene known as thymic stromal lymphopoietin (TSLP) gene, is found on chromosome 5q22.1 and is produced by epithelial cells that line the surfaces of the body. TSLP gene over expression has been shown to contribute to other allergy related diseases such as asthma and eczema in prior studies.
There is much more researched needed in this area of study to determine if treatment to reduce TSLP expression will be beneficial. However, identification is a very crucial step and this article provides potential groundwork for future developments of treatments and better understanding of the genetic basis of allergies.
Rothenberg, ME et al. Common variants at 5q22 associate with pediatric eosinophilic esophagitis. Nature Genetics (2010).