Micro-RNAs in ALS muscle: Differences in gender, age at onset and disease duration

Few studies have explored the role of microRNAs (or miRNAs) in Amyotrophic Lateral Sclerosis (ALS) muscle, possibly because of the difficulty in obtaining samples and because this is a rare disease. We measured the expression levels of muscle-specific miRNAs (miRNA-1, miRNA-206, miRNA-133a, miRNA-133b, miRNA-27a) and inflammatory/angiogenic miRNAs (miRNA-155, miRNA-146a, miRNA-221, miRNA-149*) in the muscles of 13 ALS patients and controls. To highlight differences, patients were subdivided according to their gender, age at onset of symptoms, and disease duration. A significant over-expression of all miRNAs was observed in ALS patients versus controls, in male patients versus females, in patients with early onset versus patients with late onset, and in patients with long disease duration versus patients with short duration. A differential expression of miRNAs according to gender could be explained by the hormonal regulation which determines the body muscle mass. The course of the disease might reflect differential degree of muscle atrophy and signaling at miRNA levels. An evident role is also played by inflammatory/angiogenetic factors as shown by the observed miRNA changes.