Figure 3. L. interrogans transmigrates across endothelial cell monolayers more efficiently than does L. biflexa.

Ea.hy926 and HMEC endothelial cells were placed in 3 µm transwell inserts (“upper chambers”) in 24 well dishes containing medium and allowed to reach complete confluence (assessed visually and with FITC-dextran 40,000). The bacteria were added at MOI = 50 (providing sufficient numbers for quantification) to wells with and without endothelial cells, and samples were taken for counting from both chambers of the transwell plates at the times indicated. The graphs show bacteria that have migrated from upper to lower chamber (i.e. transmigration) as the percent of the total in both the upper and lower chambers. Shown are the means ± standard deviations of 3 independent experiments. For L. interrogans sv. Copenhageni and Canicola, the rates of transmigration through membranes with and without cells were not statistically significant as assessed by repeated measures ANOVA followed by Bonferroni's multiple comparison test (P>0.05). For L. biflexa, the same comparison was significantly different, P<0.001. In addition, the L. interrogans strains were significantly different from L. biflexa in crossing the cell layers (P<0.05).