Changes in endothelial permeability induced by purified P falciparum merozoite proteins. HDMECs (105) seeded in transwells were incubated until 3 days after confluence. Intact merozoites from the parasite line 3D7 were added for 24 hours. Endothelial permeability was increased in a threshold-dependent manner as determined by (A) the flux of FITC-albumin and (B) transendothelial resistance (n = 4.) (C) The activity of intact merozoites was inhibited by pretreatment of merozoites with proteinase K (10 U/mL) or trypsin (10 μg/mL) overnight (16 h; n = 4). (D) Morphologic changes in ZO-1 and VE-cadherin staining as described for parasite sonicates were also seen in HDMECs incubated with intact merozoites. Results are representative of 3 independent experiments. *P < .05, **P < .01 compared with control values by Student paired t test. For multiple comparisons †P < .05 by ANOVA with post hoc analysis by Tukey test. (A-C) Results are expressed as mean (± SD).
