Purpose of review
Cachexia is a complex syndrome characterized by body weight loss, tissue wasting, systemic inflammation, metabolic abnormalities, and altered nutritional status. One of the most prominent features of cachexia is the loss of muscle mass, mainly because of increased protein degradation rates. This review is aimed at discussing the involvement of autophagy in the pathogenesis of muscle wasting in cachexia.
Modulations of muscle mass in the adult reflect an imbalance between protein synthesis and degradation rates. Muscle depletion in cachexia is associated with increased protein breakdown, mainly involving the pathways dependent on ubiquitin–proteasome and autophagy–lysosomes. This latter, in particular, was considered not relevant for a long time. Just in the last years, autophagy was shown to contribute to the pathogenesis of muscle wasting not only in myopathies because of intrinsic muscle defects, but also in muscle depletion associated with conditions such as sepsis, chronic obstructive pulmonary disease, glucocorticoid treatment, cancer cachexia, and aging.
The present review highlights that both excess and defective autophagy are relevant to the onset of muscle depletion, and draws some considerations about possible therapeutic intervention aimed at modulating autophagy in order to improve muscle trophism.