Gut microbiota and metabolic aspects of cancer cachexia

Cancer cachexia is a metabolic syndrome characterized by unintended weight loss and muscle wasting. It has a strong negative impact on survival. Its underlying mechanisms involve systemic inflammation and insulin resistance, which are known to be influenced by the gut microbiota. Preclinical studies support a role for the gut microbiota in cancer cachexia by demonstrating that cachectic mice display: 1) various gut microbiota composition changes; 2) increased gut permeability and translocation of pro-inflammatory microbial compounds; 3) muscle atrophy-related processes linked to gut microbiota properties; 4) positive effects of microbiota-modulating interventions. Data on the relationships between gut microbiota, insulin resistance, and hepatic/adipose tissue metabolism in cachexia models are lacking. Nevertheless, the available data and existing evidence for the impact of gut microbiota on metabolic aberrations in human obesity urge for exploration of its role in human cancer cachexia. We provide practical recommendations and discuss the challenges for such future clinical studies.