Arctigenin Confers Neuroprotection Against Mechanical Trauma Injury in Human Neuroblastoma SH-SY5Y Cells by Regulating miRNA-16 and miRNA-199a Expression to Alleviate Inflammation

Mechanical trauma injury is a severe insult to neural cells. Subsequent secondary injury involves the release of inflammatory factors that have dramatic consequences for undamaged cells, leading to normal cell death after the initial injury. The present study investigated the capacity for arctigenin (ARC) to prevent secondary effects and evaluated the mechanism underlying the action of microRNA (miRNA)-199a and miRNA-16 in a mechanical trauma injury (MTI) model using SH-SY5Y cells in vitro. SH-SY5Y cells are often applied to in vitro models of neuronal function and differentiation. Recently, miRNAs have been demonstrated to play a crucial role in NF-kappa B and cholinergic signaling, which can regulate inflammation. The cell model was established by scratch-induced injury of human SH-SY5Y cells, which mimics the characteristics of MTI. A cell counting kit-8 (CCK-8), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunocytochemistry were used to measure cell viability. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the inflammatory cytokine and cholinesterase (CHE) content. The lactate dehydrogenase (LDH) content was measured to assess the degree of cell injury. The mRNA levels were measured by RT-PCR to analyze ARC's mechanism of action. miRNA inhibitors and mimics were used to inhibit and strengthen the expression of miRNAs. Protein expression was detected by western blotting analysis. ARC treatment reduced the TNF-alpha and IL-6 levels as well as the number of TUNEL+ apoptotic SH-SY5Y cells surrounding the scratch and increased the IL-10 level compared to the controls. ARC attenuated the increase of the cell damage degree and LDH content induced by scratching, indicating increased cell survival. Mechanistic studies showed that ARC upregulated the miRNA-16 and miRNA-199a levels to reduce upstream protein (IKK alpha and IKK beta) expression and inhibit NF-kappa B signaling pathway activity; moreover, the increased miRNA-199a suppresses cholinesterases to increase cholinergic signaling, resulting in decreased expression of proinflammatory cytokines. ARC treatment confers protection for SH-SY5Y cells through positive regulation of miRNA expression, thereby reducing the inflammatory response. In turn, these effects accelerate injury repair in the scratch-induced injury model. These results might provide insights into the pharmacological role of ARC in anti-inflammation and neuroprotection in neural cells.