Distinct gut microbial communities and metabolic functions are associated with cachexia in lung cancer patients

Abstract Background Cachexia is associated with decreased survival in cancer patients and has a prevalence of up to 80%. The etiology of cachexia is poorly understood, and limited treatment options exist. Here, we investigated the role of the human gut microbiome in the clinical setting by integrating shotgun metagenomics and plasma metabolomics of 38 lung cancer patients, with known cachexia status. Results The cachexia group showed significant differences in the gut microbial composition, functional pathways of the metagenome, and the related plasma metabolites compared to non-cachectic patients. Branched-chain amino acids (BCAAs), methylhistamine, as well as vitamins, were significantly depleted in the plasma of cachexia patients, which was also reflected in the depletion of relevant gut microbiota functional pathways. The enrichment of plasma BCAAs and 3-oxocholic acid in non-cachectic patients were positively correlated with the gut microbial species Prevotella copri and Lactobacillus gasseri, respectively. Furthermore, the gut microbiota capacity for lipopolysaccharides biosynthesis was significantly enriched in the cancer cachectic patients. The involvement of gut microbiome in cachexia was further observed in a high-performance machine learning model that uses solely gut microbial taxonomic and pathway features to differentiate cachectic from non-cachectic cancer patients. Conclusions Our study demonstrates the links between host metabolism and specific gut microbial species and functions in a clinical setting, suggesting that the gut microbiota could have an influence on cachexia with possible future therapeutic applications.