Fig. 2
Zerumbone reduces inflammation and promotes the phenotypic conversion of microglia in vitro. The murine N9 microglial cell line and primary microglia isolated from newborn mice were stimulated with lipopolysaccharide (1 μg/ml) or β-amyloid (Aβ; 10 μM), and incubated with or without zerumbone (1, 3, or 10 μg/ml) for 24 h. a Bar graph showing the nitric oxide (NO) concentration in N9 cells. Zerumbone treatment significantly reduced NO production. b Bar graph showing the expression levels of indicated genes including interleukin-1β (IL-1β), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), CD206, interleukin-10 (IL-10), and arginase-1 (ARG-1) in N9 cells. Zerumbone treatment significantly decreased the mRNA levels of IL-1β, IL-6, iNOS, and TNF-α, and increased the mRNA levels of CD206, IL-10, and ARG-1 in a dose-dependent manner. c The purity of primary microglia was identified using flow cytometry, and CD11b+/CD45low cells were confirmed as microglia. d, e Cell counting kit-8 (CCK8) experiments showed that neither Aβ nor different doses of zerumbone affected cell number or viability. f Bar graph showing the NO concentration in primary microglia cells. Zerumbone treatment significantly reduced NO production. g Bar graph showing the expression levels of indicated genes including IL-1β, IL-6, iNOS, TNF-α, CD206, IL-10, and ARG-1 in primary microglia. Zerumbone treatment significantly decreased the mRNA levels of IL-1β, IL-6, iNOS, and TNF-α, and increased the mRNA levels of CD206, IL-10, and ARG-1 in a dose-dependent manner. h Bar graph showing the concentrations of cytokines (IL-1β, TNF-α, and IL-10) in the cell culture supernatants of primary microglia. Zerumbone treatment significantly decreased the levels of IL-1β and TNF-α, and increased the levels of IL-10. i Fluorescence-activated cell sorting (FACS) results and a bar graph showing that zerumbone increased the phagocytosis of Aβ in microglia cells. Data are presented as median and interquartile ranges (n = 5). *p < 0.05, **p < 0.01