Group B Streptococcus Hijacks the Host Plasminogen System to Promote Brain Endothelial Cell Invasion (original) (raw)
Figure 1
Plasmin(ogen)-coated GBS displays enhanced abilities to adhere to and invade hBMECs in vitro.
(A) GBS cells were incubated with FITC-labeled human plasminogen (hPLG) (grey filled histogram) or PBS (white dotted histogram). Plasminogen binding was measured by a FACScan cytometer as the increase in FITC mean fluorescent intensity (MFI). Each histogram shows cell number as a function of relative fluorescence obtained for 10,000 events per population. Results are shown for 10, 20, and 50 µg of FITC-conjugated hPLG. (B) Representative growth curves of GBS preincubated without (untreated GBS) or with (PLG-treated GBS) plasminogen plus tPA in complete hBMEC growth medium. Data are from a experiment performed in triplicate that is representative of three independent experiments. Each point is the mean of three samples ± SEM. (C and D) HBMEC monolayers were infected with 106 cells of GBS preincubated without (untreated GBS) or with (PLG-treated GBS) plasminogen plus tPA (MOI of 10 bacteria per cell). (C) HBMECs surface adherent GBS cells and (D) intracellular bacteria were isolated and enumerated after 30, 60, and 90 min of infection. The percentages of hBMECs surface adherent GBS and intracellular bacteria are expressed relative to the initial inoculums. Data are the mean + SEM of three independent experiments. Statistical differences (P values) are indicated; ND – not detected.