1,25-Dihydroxy Vitamin D₃ Facilitates the M2 Polarization and β-Amyloid Uptake by Human Microglia in a TREM2-Dependent Manner

Figure 4

1,25(OH)₂D₃ enhances surface TREM2 expression and Aβ42 uptake by HMO6 cells. (a) Cells were treated with different concentrations of 1,25(OH)₂D₃ in the presence of 100 nM Aβ42 for 12 h, and cell surface expression of TREM2 was measured by flow cytometry. (b) Cells were treated with 100 nM Aβ42 in the presence or absence of 1 μM 1,25(OH)₂D₃ at 37°C for different periods, and the levels of intracellular Aβ were measured by flow cytometry using anti-Aβ antibodies. (c) The culture supernatants were collected, and levels of Aβ were measured by ELISA. (d) Cells were treated with or without TREM2-blocking antibodies for 2 h and then treated with 100 nM Aβ42 in the presence or absence of 1 μM 1,25(OH)₂D₃ at 37°C for 24 h, after which, the levels of intracellular Aβ were measured by flow cytometry. Bar graphs indicate the relative (left panels). Right panels designate representative histograms. (e) Culture supernatants were collected, and levels of Aβ were measured by ELISA. and vs. the DMSO control. ^##.

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