Fig. 3

Neuroprotective effect of conditioned media from activated microglia after cholesterol enrichment. Cells were cholesterol-enriched by incubation with the CHO:MCD complex for 1 h. After 4 h of recovery, cells were stimulated with LPS (10 μg/ml) plus MDP (10 μg/ml) for 16 h. a NGF and BDNF secretion. Cell culture media were collected after the indicated treatments and the levels of both neurotrophins were analyzed by ELISA. The protein concentration of cell extracts was used for data normalization (n = 4–5 independent experiments). b and c Analysis of cell death by LDH assay. Primary neuronal cell cultures (b) and SH-SY5Y cells (c) were first incubated for 16 h with conditioned media (CM) from SIM-A9 cells treated as indicated (CM1: mock, CM2: CHO:MCD exposure for 1 h, CM2: 10 μg/ml LPS + 10 μg/ml MDP induction for 16 h, and CM4: CHO:MCD exposure for 1 h followed by LPS + MDP induction for 16 h). Then, cells were exposed to Aβ for 24 h. LDH activity was determined in the cell culture media and normalized to total cellular LDH content. Results are expressed as % relative to the untreated control values. (n = 4–5 independent experiments). One-way ANOVA followed by the Tukey–Kramer test was applied to calculate statistical significance (*P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001)