US researchers have made a discovery that could prove critical in treating or even preventing the development of autoimmune diseases such as arthritis, type 1 diabetes and multiple sclerosis. Led by Dr Andrew L. Mellor, a team from the Medical College of Georgia (MCG) at Georgia Regents University has established that a protein called STING could play a critical role in that, with some additional stimulus.
The study report, published in the Journal of Immunology, explains that STING can temper the immune system response and even stop it from attacking healthy constituents in the body such as collagen, insulin and the neurons´ protective cover. These are all targets of the above-mentioned autoimmune diseases.
The researchers observed the part played by STING through a lab experiment involving mice genetically programmed to develop an autoimmune disease. Last year, this team was the first to establish that DNA nanoparticles injected in the blood stream were capable of suppressing immunity by triggering the release of indoleomine 2,3-dioxyegenase (IDO) in mice affected by arthritis. This time, the researchers became aware that STING was actually capable of turning off the immune system: it recognises the DNA-sensing molecule and then provokes the release of IDO. This is the first time scientists have come to realise that STING constitutes part of the DNA-sensing pathway.
The interesting thing about this protein is that it can either block or prompt an immune response depending on the way it is evoked. The MCG team got suppression by injecting the stimulus into the bloodstream. Other researchers have achieved the opposite result by injecting reagents under the skin. Mellor and his colleagues will now focus on finding the best way of activating STING. Their future research will involve comparison of the results achieved by stimulation through DNA nanoparticles and through more direct activation by cyclic dinucleotides.