Figure 10

Plasminogen activator inhibitor type 1 (PAI-1) inhibited microglial phagocytosis of zymosan particles. (A) BV-2 microglial cells were treated with PAI-1 (100 or 1000 ng/ml) for 1 hour and then incubated with zymosan particles conjugated with Alexa Fluor 594 (red) for 3 hours. Cells were washed five times with ice-cold PBS to remove bound particles. (A) Images at five different locations were taken and then the percentage of phagocytic cells was calculated based on the number of microglial cells that phagocytosed the zymosan particles (lower panel). (Upper panel) Representative images are shown. Results are given as mean ± SD from three independent experiments. *P < 0.05, **P < 0.01, different from untreated control. Scale bar = 20 μm. (B) BV-2 microglial cells were treated with BSA (2.2 or 22 nmol/l) or PAI-1 (2.2 nmol/l; 100 ng/ml) for 1 hour and then incubated with zymosan particles for 3 hours, followed by the phagocytosis assay as described above. Results are given as mean ± SD from three independent experiments. *P < 0.05, NS = not significant, compared with the untreated control. Scale bar = 20 μm. (C) Primary microglia were treated with BSA (100 ng/ml), PAI-1 (100 ng/ml), or RAP protein (5 μg/ml) for 1 hour and then incubated with zymosan particles for 90 minutes. Microglial phagocytosis was assessed as described above. Results are given as mean ± SD (n = 3). *P < 0.05, NS = not significant.