Alteration of microRNA Expression Associated with Chronic Back Pain in Patients with Intervertebral Disc Degeneration: A Scoping Review

Chronic back pain (CBP) associated with intervertebral disc degeneration (IVDD) is a leading cause of medical consultations, decreased quality of life, and temporary and permanent disability. The mechanisms of CBP development and persistence in patients with IVDD have been studied for many years, but this issue remains far from resolved. The search for predictive biomarkers that could help identify patients with IVDD at high risk for CBP continues. In recent decades, research has shown increasing interest in identifying epigenetic biomarkers for this disorder. to summarize the results of preclinical and clinical studies on the role of microRNAs (miRs) as epigenetic biomarkers of the development and progression of CBP in patients with IVDD. English-language articles; original experimental (preclinical) studies; original clinical study; assessment of changes in systemic (in the blood) and/or local (in the intervertebral disk (IVD)) levels of miR expression in IVDD, either independently or in comparison with healthy controls; and studies that were completed and the results of which were published. PubMed, Springer, Google Scholar, Scopus, Oxford Press, Cochrane, and e-Library databases. Charting for this scoping review involved developing a data extraction form to summarize extracts and organize data from included studies. This was an iterative process where the charting tables and figures may be refined as the review progresses. 126 studies were analyzed in detail, focusing on their study designs and comparing changes in miR expression in animal models of IVDD and in patients with IVDD compared to healthy controls. During the preparation of this scoping review and upon subsequent detailed review of the original publications, it turned out that the results of one study were not justified by the authors due to identified technological problems (the article was withdrawn by the editorial board of the journal). Therefore, we excluded the results of this study from the subsequent analysis. As a result, this section summarizes the results of 60 preclinical and 65 clinical studies. Some miRs (e.g., miR-21 and miR-132) are associated with the regulation of inflammatory pathways that contribute to increased degradation of IVD extracellular matrix and enhanced nociceptive signaling through various mechanisms, contributing to the progression of CBP. Other miRs (e.g., miR-145 and miR-223) exert protective effects, enhance regenerative potential, and alleviate CBP. Despite the promising results of these studies, there are limitations in the use of miRs as perspective epigenetic biomarkers of CBP in patients with IVDD because the pattern of potentially predictive and protective miRs in relation to the mechanisms of CBP formation and progression in IVDD has not yet been sufficiently studied. The results of some preclinical and clinical studies are contradictory. Further research is needed to clarify the role of miR signatures in animal models and clinical trials on IVDD-specific CBP.