Fig. 1

Polarization of primary microglia by lipopolysaccharide (LPS) and interleukin-4 (IL4). *p < 0.05, **p < 0.01, *** p < 0.001 compared to control; ^#p < 0.05, ^##p < 0.01, ^###p < 0.001 compared to different experimental group as marked by horizontal bar. a Representative immunocytochemical stainings for the microglia marker “ionized calcium-binding adapter molecule 1” (Iba1; red), co-stained for “inducible nitric oxide (NO) synthetase” (iNOS; green), and Hoechst 33342 (Hoechst) as a nuclear counterstain (blue); scale bar = 50 μm. b Characterization of the M1 microglia phenotype by expression of iNOS, release of NO, and M1-characteristic cytokines after treatment with LPS (1 and 10 ng/ml) or IL4 (50 ng/ml). INOS expression was measured on the RNA level by real-time quantitative PCR (RT-qPCR; n = 3, H(3) = 25.828, p < 0.001) and on the protein level by immunocytochemistry (n = 3, H(3) = 97.262, p < 0.001). Release of NO was measured by Griess assay (μmol/l; n = 4, H(3) = 23.176, p < 0.001). Release of tumor necrosis factor-α (TNF-α; ng/ml, n = 3, H(3) = 22.112, p < 0.001) and interleukin-6 (IL6; ng/ml, n = 3, H(3) = 21.588, p < 0.001) were measured by enzyme-linked immunosorbent assay (ELISA). c Characterization of the M2 microglia phenotype by expression of CD206 and release of M2-characteristic cytokines after treatment with LPS or IL4. Regulation of CD206 expression on the RNA level was measured by RT-qPCR (representative experiment, F (3, 11) = 69.671, p < 0.001, ω = 0.972). Insulin-like growth factor 1 (IGF1) release was measured by ELISA (pg/ml, n = 3, F (3, 27) = 7.082, p < 0.001, ω = 0.63)