Feng Lv, Yingzi Huang, Wentao Lv, Longbiao Yang, Feng Li, Jingli Fan, Jianmin Sun
(Department of Spine Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China (mainland))
Med Sci Monit 2017; 23:659-664
Intervertebral disc degeneration (IDD) has been widely recognized as a major contributor to low back pain. Accumulating evidence suggests that IDD is linked to various pro-inflammatory cytokines and metabolites. Recently, numerous studies have demonstrated that microRNAs (miRNAs) play a pivotal role in the development of most disorders, including degenerative disc diseases. Previous reports have revealed that miRNA-146a (miR-146a) could attenuate neuropathic pain in the spinal cord. The aim of this study was to investigate the role of miR-146a in the inflammatory response of IDD.
MATERIAL AND METHODS: Quantitative real-time (RT)-PCR was performed to investigate the levels of miR-146a in the PBMCs (peripheral blood mononuclear cells) of patients with IDD. Human nucleus pulposus (NP) cells were transiently transfected with miR-146a mimic; control NP cell transfections lacked miR-146a. Then all NP cells were treated with LPS (10 μM) to induce inflammation. The mRNA levels of miR-146a in NP cells were determined by RT-PCR. In addition, the mRNA and protein expression levels of tumor necrosis factor (TNF), receptor-associated factor 6 (TRAF6), and nuclear factor (NF)-κB in NP cells were evaluated by quantitative RT-PCR and Western blot analysis, respectively.
RESULTS: We found that miR-146a was significantly downregulated in the PBMCs of patients. Moreover, overexpression of miR-146a significantly decreased the levels of pro-inflammatory cytokines in LPS-stimulated NP cells. The mRNA and protein levels of TRAF6 and NF-κB were downregulated by miR-146a overexpression.
CONCLUSIONS: These results suggest that overexpression of miR-146a could promote IDD through the TRAF/NF-κB pathway. Our findings also highlight miR-146a as a novel possible therapeutic target for IDD.
Keywords: Inflammation, intervertebral disc degeneration, MicroRNAs, NF-kappa B, TNF Receptor-Associated Factor 6