Cachexia syndrome develops in patients with diseases such as
cancer and
sepsis and is characterized by progressive muscle wasting. While iNOS is one of the main effectors of
cachexia, its mechanism of action and whether it could be targeted for
therapy remains unexplored. Here, we show that iNOS knockout mice and mice treated with the clinically tested iNOS inhibitor
GW274150 are protected against muscle wasting in models of both septic and
cancer cachexia. We demonstrate that iNOS triggers muscle wasting by disrupting mitochondrial content, morphology, and energy production processes such as the TCA cycle and
acylcarnitine transport. Notably, iNOS inhibits oxidative phosphorylation through impairment of complexes II and IV of the electron transport chain and reduces
ATP production, leading to energetic stress, activation of AMPK, suppression of mTOR, and, ultimately,
muscle atrophy. Importantly, all these effects were reversed by
GW274150. Therefore, our data establish how iNOS induces muscle wasting under cachectic conditions and provide a proof of principle for the repurposing of iNOS inhibitors, such as
GW274150 for the treatment of
cachexia.