Objective To investigate the effects of zinc oxide nanoparticle (nano-ZnO) on expression of inflammatory factors and phosphorylation of p38 mitogen-activated protein kinases (p38MAPK) in BV2 microglia.
Methods BV2 cells were treated with different concentrations of nano-ZnO (0, 5.0, 10.0, 15.0, 20.0, 30.0, 50.0, and 75.0 mg/L) for 24 h. MTT assay was used to assess the viability of BV2 cells and determine the exposure concentration. Then, BV2 microglia were treated with nano-ZnO (0, 5.0, 10.0, 15.0, and 20.0 mg/L) for 24 h, and the levels of lactate dehydrogenase (LDH) was detected by LDH detection kit, the secretion of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6 by ELISA, the protein levels of phosphorylated p-38MAPK (p-p38MAPK) by Western Blot, and the gray value of protein band by Image J software. The relationship between the expression of inflammatory factors and the protein level of p-p38MAPK was analyzed by Spearman correlation analysis.
Results Increasing nano-ZnO treatment significantly decreased the viability of BV2 cells (r=-0.994, P < 0.001) and increased the activity of LDH (r=0.749, P < 0.001). Compared to the control group, the levels of TNF-α, IL-1β, and IL-6 increased in the 10.0, 15.0, and 20.0 mg/L nano-ZnO exposure groups (Ps < 0.05). Western bolt results showed that the expression levels of p-p38MAPK increased in the nano-ZnO exposure groups and were consistent with the change trend of inflammatory factor levels (rTNF-α=0.836, P < 0.001; rIL-6=0.539, P < 0.001; rIL-1β=0.659, P=0.008). The grey value ratio of p-p38MAPK and p38MAPK was higher in the 20.0mg/L nano-ZnO exposure group than in the control group (P < 0.05).
Conclusion Exposure to nano-ZnO could induce elevated secretion levels of inflammatory cytokines and expression levels of p38MAPK phosphorylation in BV2 microglia.
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