Figure 3.

TREM2 stimulation up-regulates CCR7 and increases migration of microglia toward CCL19 and CCL21. Primary murine microglia were transduced with fTREM2 or GFP control vector. Microglia were cultured on dishes coated with cross-linking antibody directed against the Flag epitope (+) or a control antibody (−). (A) Primary microglia were transduced with fTREM2 or GFP control vector and cultured on dishes coated with cross-linking antibody directed against the Flag epitope (red line) or control antibody (blue line) for 72 h. Cells were analyzed by flow cytometry after staining by specific antibodies directed against MHC class II, CD86, CD11c, CD36, and CCR7. Staining of cells with an isotype control antibody was performed (gray filled). A slight increase in CCR7 expression was observed in fTREM2-transduced microglia after stimulation of TREM2, which was not detected in the control vector–transduced microglia. (B) TREM2 stimulation directs migration of microglia toward the CCR7 ligands CCL19 and CCL21. fTREM2-transduced microglia stimulated for 24 h with precoated 10 μg/ml antibody directed against the Flag epitope (white bars), 10 μg/ml isotype control antibody (black bars), or LPS (gray bars) were tested in transwell chemotaxis assays for their ability to migrate toward medium alone or medium supplemented with CCL19 or CCL21. Microglia showed increased migration toward CCL19 and CCL21. *, P < 0.05; Mann-Whitney U test.