Lipopolysaccharide from Rhodobacter sphaeroides Attenuates Microglia-Mediated Inflammation and Phagocytosis and Directs Regulatory T Cell Response

Figure 4

LPS-Rs diminished microglial phagocytic activity. Microglia phagocytic activity was measured by bacterial colony forming unit (CFU) count (a). BV2 microglia were pretreated with LPS-Rs (5 μg/mL) or Cytochalasin D (10 µM) for 2 hrs before LPS (1 μg/mL) treatment for 24 hrs. The cells were then infected with DAPI stained E. coli DH5α. After 30 min gentamicin (200 µg/mL) was added for 1 hr to kill extracellular bacteria and intracellular bacterial load was assayed using fluorescence microscopy at 40x magnification (b). The error bars represent the mean ± SEM from three independent experiments ( versus control and versus LPS). UN: untreated; LPS: lipopolysaccharide from Escherichia coli 055 : B5 (1 µg/mL); RS: lipopolysaccharide from Rhodobacter sphaeroides (0.5–5 µg/mL); Cyto D: Cytochalasin D.

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