Treatment of inflammation via activation of the mRNA-destabilising protein tristetraprolin

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Inflammation is a healthy response to infection or physical damage, which helps to eliminate harmful microbes. However, many of the factors released during an inflammatory response cannot discriminate between self and microbe, and therefore risk causing collateral damage to the inflamed tissue. For this reason, inflammation is usually very tightly regulated. A healthy inflammatory response has a rapid onset and an orderly resolution phase, in which activated immune cells exit the inflamed tissue or return to their resting state. This allows normal function of the affected tissue to be restored with minimal damage. An inflammatory trigger can be thought of as an accelerator pedal, and resolution as the brake: safe driving requires judicious use of both.Inadequately controlled, damaging inflammation is the defining characteristic of chronic diseases like rheumatoid arthritis, chronic obstructive pulmonary disease, inflammatory bowel disease and many others. Uncontrolled inflammation also strongly contributes to cardiovascular disease, neurodegenerative conditions like Alzheimer's disease, and many forms of cancer. For decades the main focus of researchers on these diseases has been to identify triggers of inflammation and try to block their effects. This approach has met with only moderate success, and the overall economic, societal and personal burdens of chronic inflammatory disease continue to grow in the developed world. The focus on triggers of inflammation risks overlooking the equally important process of resolution. Evidence both from genetic studies of human disease and from animal experiments clearly shows that inflammatory disease can be caused or made worse by defects in the "braking" mechanisms that underlie resolution. More and more researchers are now trying to understand the biological processes involved in the resolution of inflammation. It is thought that reinforcement of resolution mechanisms may be an effective way to treat inflammatory diseases.Our research on a protein called tristetraprolin (TTP) develops the concept of reinforcing resolution. Mice that cannot produce TTP develop severe, spontaneous inflammatory disease, therefore we know that TTP is an important brake to inflammation. We have also learned that the function of TTP is controlled by a molecular switch that converts it between active and inactive states. We can detect a lot of TTP protein in chronically inflamed joints of patients with rheumatoid arthritis, but it seems to be in the inactive state. We suspect that the persistent inactivation of TTP prevents resolution of inflammation, much like a faulty brake. We believe it will be possible to reduce inflammation by restoring the function of TTP, effectively repairing the damaged brake. To do this, we plan to use two different drugs that we predict will switch TTP from inactive to active state. One of these drugs is already used to treat multiple sclerosis, whilst the other is being investigated as a potential treatment for cancer. If this work is successful it may lead to new clinical trials, and ultimately to an entirely new type of treatment for inflammatory diseases, one that is based on promoting resolution rather than blocking inflammatory triggers.