Fig. 3

Microglia are the main source of GDF15 in the brains of septic mice. (A-B) Quantitative polymerase chain reaction (qPCR) analysis of Gdf15 mRNA expression in the indicated primary cells sorted from the cortices (A) and hippocampi (B) of LPS-induced septic mice (n = 3). (C) Representative images of immunofluorescence staining of Iba1 and GDF15 in the hippocampi of septic mice. Red, Iba1; green, GDF15; blue, DAPI; scale bar, 50 μm and 5 μm. (D) Quantification of the ratio of GDF15⁺Iba1⁺/Iba1⁺ cells in (C). (E) qPCR analysis of Gdf15 mRNA expression in the indicated cells treated with LPS (1 µg/ml) for the specified times. (F) Volcano plots of BV2 cells treated with LPS (1 µg/ml) for 6 h. Red, upregulated genes; blue, downregulated genes. (G) Western blotting showing GDF15 protein expression in BV2 cells (upper panel) and primary microglia (lower panel) treated with LPS (1 µg/ml) for the specified times. (H) ELISA measurements of GDF15 concentrations in the culture supernatants of BV2 cells treated with LPS (1 µg/ml) for the specified times. (I) qPCR analysis of Gdf15 mRNA expression in BV2 cells treated with the indicated LPS concentrations for 3 h. Gapdh was used as an endogenous reference for qPCR. Bars indicate means ± SEM. **P < 0.01, ***P < 0.001, ****P < 0.0001