MicroRNA and chronic pain: From mechanisms to therapeutic potential.

Chronic pain is a major public health issue with an incidence of 20-25% worldwide that can take different forms like neuropathic, cancer-related or inflammatory pain. Chronic pain often limits patients in their daily activities leading to despair. Thus, the goal of treatments is to relieve pain sufficiently to enable patients to go back to a normal life. Unfortunately, few patients with chronic pain obtain complete relief from the analgesics that are currently available. It is thus of prime importance to get a better understanding of chronic pain mechanisms to design new therapeutic strategies and pain-killers. In this sense, the study of microRNA (miRNAs) in chronic pain conditions could lead to a breakthrough in pain management. miRNAs have emerged as master regulators of gene expression in the nervous system where they contribute to neuronal network plasticity. The involvement of miRNAs in the maladaptive plasticity mechanisms of chronic pain is now well documented. Here, we review studies conducted in different animal models and in patients that screened chronic pain-related miRNAs and their targets. Clinical studies suggest that miRNAs expression could reflect the high variability among pain patients that could help to categorize patients and finally lead to personalized therapies. We also point out the different strategies investigated to design miRNA-based analgesics. Finally, we highlight the current miRNA-based clinical trials to hypothesize their potential as therapeutic tool for chronic pain.