M30 is an antibody that recognizes a specific caspase cleavage site within cytokeratin 18 that is not detectable in native cytokeratin 18 of vital cells. This occurs early in the apoptosis cascade, before Annexin-V reactivity

or positive DNA nick labeling. Untreated cells were used as a negative control and cells treated with camptothecin 4 μg/ml for 4 hours, an apoptosis-inducing agent, were the positive control. Cells challenged with live or heat-killed bacteria at an MOI:10 showed no positive staining at any time point (data not shown). Cells challenged with live or heat-killed bacteria at an MOI:100 and MOI:1000 did not show any positive staining at 4 hours (data not shown). The epithelial cells appeared morphologically normal under all of the above conditions. However, challenge with live P. gingivalis at an MOI:100 for 24 Selleckchem Danusertib hours increased the detachment of cells, while the remaining attached cells showed signs of blebbing, had pyknotic nuclei, and stained positive for M30 epitope, an early

sign of apoptosis (Fig. 1C). In contrast, cells challenged with heat-killed P. gingivalis at an MOI:100 for 24 hours did not show any signs of apoptosis (Fig. 1D). Cells challenged with live P. gingivalis at an MOI:1000 for 24 hours completely detached from the plate, thus MOI:1000 was not used for subsequent experiments. Figure 1 M30 epitope immunohistochemistry was used to detect caspase-cleaved cytokeratin-18 which is detectable Epacadostat ic50 in early stages of apoptosis. Images are fluorescent confocal staining at ×600 magnification. The negative control was unchallenged HGECs with only media added (A). The positive control was HGECs treated with camptothecin 4 μg/ml for 4 hours (B). HGECs challenged with live P. gingivalis 33277 at MOI:100 for 24 hours show marked staining (C), while HGECs challenged with heat-killed bacteria under the same conditions show no detectable apoptosis (D). Challenging HGECs with an MOI:100 for 4 hours or MOI:10 for 4 and 24 hours showed

no positive staining (no apoptosis) (data not shown). Live but not heat-killed P. gingivalis induce caspase-3 activation in HGECs in a time-dependent manner HGECs were challenged with live or heat-killed P. gingivalis 33277 at an MOI:100 for 4 and 24 hours and caspase-3 activity was measured fluorometrically. Caspase-3 is an executioner caspase see more involved also in both the extrinsic and intrinsic pathway of apoptosis. Caspase-3 activation plays a key role in the initiation of cellular events during the early apoptotic process. Untreated cells were used as a negative control and cells treated with camptothecin were the positive control. There was no significant increase in caspase-3 activity after 4 hours challenge with live or heat-killed bacteria (Fig. 2). However, after 24 hours challenge with live P. gingivalis, caspase-3 activity increased more than 2-fold compared to the negative control.