IL-6 Protein Expression is Increased in Fast Glycolytic Muscle Fibers Over Time in the SOD1G93A Mouse model.

Abstract

The deregulation of the inflammatory cytokine interleukin (IL)-6 has been associated to a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). The aim of this work was to analyze the variation of IL-6 levels in blood and damaged tissues during the course of the disease. We studied IL-6 protein expression in spinal cord, extensor digital longus (EDL) muscle and soleus (SOL) muscle of the SOD1G93A animal model at four stages of the disease by western blot. Concurrently, we analyzed IL-6 gene and protein expression in blood of ALS patients, healthy subjects and patients with other neuropathies through RTqPCR and ELISA. The results revealed different expression patterns depending on both the tissue analyzed and the stage of the disease, showing increasing IL-6 levels in EDL muscle over time. Moreover, lower IL-6 levels in blood were found in ALS patients. The decreased levels of IL-6 in blood from ALS patients could suggest that IL-6 might not be the main pro-inflammatory biomarker in the last stages in whole blood. In contrast, IL-6 may play a main role in fast glycolytic muscle fibers associated with muscle atrophy, suggesting that modulation of IL-6 in this tissue could be a potential target for anti-inflammatory therapies in ALS.