Abstract: Objective To explore the effects of sulforaphane (SFN) and Aβ25-35 fibers (fAβ25-35) on M1/M2 polarization of BV-2 cells and neuroinflammation-mediated programmed necrosis of neural stem cells. Methods BV-2 cells treated with different concentrations of fAβ25-35 and SFN were examined for changes in cell viability using the CCK-8 kit. The effect of fAβ25-35 alone or in combination with SFN or SB203580 on expressions of IL-6 and TNF-α mRNA and proteins were assessed in BV-2 cells using RT-qPCR and ELISA. CD16/32 and CD206 in the treated cells were analyzed with flow cytometry, and the cellular expressions of p-p38 and p-p65 protein were detected with Western blotting. C17.2 cells co-cultured with BV-2 cells for 24 h were examined for p-mlkl protein expression using Western blotting. Results fAβ25-35 at the concentration of 6.25 μmol/L significantly increased the viability of BV-2 cells (P<0.01) whereas fAβ25-35 beyond 50 μmol/L decreased the cell viability (P<0.0001). Treatment of BV-2 cells with SFN below 10 μmol/L for 24 h did not significant affect the cell viability (P>0.05). BV-2 cells treated with fAβ25-35 alone, as compared with the cells in the other 3 groups, showed significantly increased IL-6 and TNF-α mRNA and protein expressions (P<0.001), enhanced CD16/32 expression (P<0.05), lowered CD206 expression (P<0.01), and increased protein expressions of p-p38 and p- p65 (P<0.01). C17.2 cells co-cultured with BV-2 cells treated with fAβ25- 35, compared with the combined treatments, showed a significant reduction in the protein expression of p-mlkl (P<0.05). Conclusion SFN reverses M1 type microglia polarization and neuroinflammation-mediated programmed necrosis of neural stem cells by downregulating the MAPK/NF-κB signaling pathway in Aβ25-35-activated BV-2 cells.

Key words: sulforaphane; Alzheimer's disease; microglia; neural stem cells; β-amyloid; MAPK; NF-κB; M1; neuroinflammation