MicroRNA-25-3p therapy for intervertebral disc degeneration by targeting the IL-1β/ZIP8/MTF1 signaling pathway with a novel thermo-responsive vector

BACKGROUND: MicroRNAs play important roles in intervertebral disc degeneration (IDD). The therapeutic effects of miRNA-25-3p on IDD and underlying mechanism are unclear. METHODS: Normal and degenerated nuclear pulposus (NP) tissue were collected. Primary NP cells were isolated and treated with different concentrations of interleukin-1β (IL-1β). IL-1β treated NP cells were interfered with miRNA-25-3p. Associated proteins IL-1β, ZIP8, MTF1, extracellular matrix (ECM) degrading enzymes MMP3, MMP13, ADAMTS5, ECM proteins type II collagen, aggrecan and MiRNA-25-3p were detected by western blotting or qRT-PCR method. Dual luciferase reporter assays were performed to determine potential targets MTF1 of miRNA-25-3p. In vitro miRNA-25-3p transfection efficiency of thermos-responsive vector was observed by fluorescence microscopy. Animal studies were conducted to observe the therapeutic effects of miRNA-25-3p mimic delivered by thermo-responsive vector. RESULTS: Compared with normal NP tissues, IL-1β, ZIP8 and MTF1 significantly increased and miRNA-25-3p significantly decreased in degenerated tissues. IL-1β promotes the expression of ZIP8 and nuclear translocation of MTF1 in NP cells. Ultimately, it promotes expression of ECM degrading enzymes and inhibits synthesis of ECM protein. MiRNA- 25-3p could inhibit the effects of IL-1β and the expression of ECM degrading enzymes, and recover the expression of ECM protein. Further investigation showed MTF1 was a target protein of miRNA-25-3p. The thermo-responsive vector could effectively deliver miRNA-25-3p into NP cells. Animal studies demonstrated miRNA-25-3p delivered by the thermo-responsive vector can delay progression of IDD CONCLUSIONS: The thermo-responsive vector delivering miRNA-25-3p could delay the progression of IDD by inhibiting IL-1β-induced effects, and may be potential therapy for IDD in future.