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Fig. 4 | Journal of Neuroinflammation

Fig. 4

From: Pneumolysin and the bacterial capsule of Streptococcus pneumoniae cooperatively inhibit taxis and motility of microglia

Fig. 4

Involvement of pSyk in the motility changes. a Pretreatment with 2.5 mM mannan diminished the inhibitory effect of D39 lysates on microglial motility in mixed glial cultures. All values represent the mean ± SEM, n = 4 independent experiments, *p < 0.05. b Increased Syk kinase phosphorylation (at positions Tyr525 and Tyr526) in microglial isolates after exposure to D39 bacterial lysate for 120 min was diminished by pretreatment with mannan. All values represent the mean ± SEM, n = 20–25 cells, *p < 0.05. c Sub-cellular distribution of phospho-Syk before and after exposure to D39 bacterial lysates in the presence and absence of 2.5 mM mannan. Microglial exposure to D39 lysates produced clustered pSyk staining around DAPI-positive areas outside the nucleus, most probably containing DNA-rich bacterial products. This clustering was fully reverted by mannan. d Enlarged fragment of the D39-treated microglia image in c, demonstrating practically a complete overlap (correlation coefficient R2 = 0.88) between the pSyk accumulation and the DAPI staining of the cytosol. The asterisk indicates a large round DAPI-enriched cytosolic structure, resembling multivesicluar body. Scale bars, 10 μm. e Exposure of mixed glial cultures to 500 nM R406 Syk-inhibitor inhibited microglial motility and enhanced filopodia formation similarly to the exposure of the cells to D39 lysates. All values represent the mean ± SEM, n = 4 independent experiments, *p < 0.05. In all bacterial lysis experiments, the lysate concentration was 20 million CFU/ml

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