Polystyrene nanoparticles carrying miR-375 alleviate inflammatory response of intervertebral disc nucleus pulposus cells via NF-κB signaling pathway

Abstract

The aim of this study was to investigate the protective role of miR-375-loaded polystyrene nanoparticles (PSNPs) in inflammatory response within nucleus pulposus cells (NPC) in intervertebral disc. RT-qPCR was used to determine the miR-375 expression in the intervertebral disc NPCs and tissues from patients with inflammatory reaction. After transfection of PS-NPs carrying miR-375, MTT and flow cytometry experiment were conducted to assess proliferation, apoptosis and cell cycle of inflammatory cells in the intervertebral disc. The relationship between miR-375-loaded PS-NPs and NF-κB pathway was analyzed using a luciferase reporter assay. miR-375 expression was decreased in inflammatory cells and intervertebral disc NPCs. Administration of PS-NPs carrying miR-375 resulted in decreased proliferation rate of NPCs when promoting cell apoptosis. PS-NP inhibitor in return suppressed apoptosis of NPCs in the intervertebral disc. The expression of NF-κB pathway was directly regulated by miR-375 PS-NPs and participated in the inflammatory response of intervertebral disc NPCs. Down-regulation of miR-375 induced continuous proliferation of inflammatory cells in the nucleus pulposus of intervertebral disc and hindered cell apoptosis. miR-375 PS-NPs can inhibit the inflammatory response of NPCs on intervertebral disc through NF-κB pathway, which provides a new direction for nano-therapeutics for inflammatory responses of intervertebral disc NPCs.