Fig. 4.

OspD2 and OspC3 regulate epithelial cell death via different pathways. HeLa cells were infected with each strain at an MOI of 100 for 20 min before the addition of gentamicin to media. (A, B, and D) At designated time points, cells were labeled with Hoechst and PI, and the percent cytotoxicity was quantified as described in Fig. 2. (C) Quantification of IL-18 secreted by infected HeLa cells at 8 h postinvasion. In D, Z-VAD-FMK, a pan-caspase inhibitor, or DMSO (vehicle control) was added to the cells at 3 h before the infection. All data are expressed as the mean ± SD of at least two experimental repeats, each with two technical replicates (n ≥ 4). *P < 0.05 as compared with WT or as indicated by brackets. n.s., nonsignificant.