Modulating interactions between TNFalpha and IGF-1 signaling pathways to reduce necrosis of dystrophic muscle

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Duchene Muscular Dystrophy (DMD) is a lethal childhood disease that affects mainly boys. These experiments will test new highly specific anti-inflammatory drugs for the potential clinical treatment of muscular dystrophies, using the mdx mouse model of human DMD. It is essential that the benefits of such anti-inflammatory drugs are fully evaluated in long term studies in mice. Two of these drugs (Enbrel and Remicade) are already in wide clinical use for inflammatory disorders and present attractive options for treatment of DMD patients due to their high specificity of action and relatively few side effects. We have shown that both of these drugs have a striking protective effect and reduce necrosis of dystrophic muscle in the mdx mouse. The benefits of these drugs (and the mouse equivalent cVIq) is due to blocking the action of the key pro-inflammatory cytokine Tumour Necrosis Factor-alpha (TNFa). However, the precise mechanism by which high levels of TNFa increase necrosis of dystrophic muscle is not clear. There are many possible pathways. Identifying which is the key pathway(s), is of central importance to design and target new drugs to treat such lethal muscle diseases. Such modulation of signalling is a major therapeutic goal. To determine which mechanism of TNFa action is responsible for muscle necrosis, experiments will investigate several signalling pathways using specific inhibitors: the drug Pifithrin to inhibit p53; soluble RAGE to block RAGE (Receptor for Advanced Glycation Endproducts); and specific inhibitory peptides to block JNK (c-Jun N-terminal kinase). The application of these inhibitors (drugs), in mice, as future therapies for muscle diseases is novel. These studies will provide much new information on TNFa related signalling that is highly relevant to the potential treatment of many diseases, including muscle wasting that is a major problem in the ageing population and in disuse atrophy and cachexia.