Role of interleukin-6 in cachexia: therapeutic implications

Purpose of review Interleukin-6 (IL-6) has emerged as a cytokine involved in cachexia progression with some cancers. This review will present the recent breakthroughs in animal models and humans related to targeting IL-6 as a cancer cachexia therapy. Recent findings IL-6 can target adipose, skeletal muscle, gut, and liver tissue, which can all affect cachectic patient recovery. IL-6 trans-signaling through the soluble IL-6R has the potential to amplify IL-6 signaling in the cachectic patient. In the skeletal muscle, chronic IL-6 exposure induces proteasome and autophagy protein degradation pathways that lead to wasting. IL-6 is also indirectly associated with AMP-activated kinase (AMPK) and nuclear factor kappa B (NF-kappa B) activation. Several mouse cancer models have clearly demonstrated that blocking IL-6 and associated signaling can attenuate cachexia progression. Additionally, pharmaceuticals targeting IL-6 and associated signaling can relieve some cachectic symptoms in cancer patients. Research with cachectic mice has demonstrated that exercise and nutraceutical administration can interact with chronic IL-6 signaling during cachexia progression. Summary IL-6 remains a promising therapeutic strategy for attenuating cachexia progression with many types of cancer. However, improvement of this treatment will require a better understanding of the indirect and direct effects of IL-6 as well as its tissue-specific actions in the cancer patient.