FIG 9.

Effect of a cathepsin B inhibitor on cell death and detachment of dead cells. RAW 264 cells pretreated with the cathepsin B inhibitor CA-074 Me (20 μM) were exposed to the S. oralis WT (MOI = 100 or 200) or H₂O₂ (1 mM) for 3 h. The cells were washed and cultured for an additional 21 h (total, 24 h) in fresh medium containing CA-074 Me (10 μM) and antibiotics (see also Fig. S2 in the supplemental material). (A) The viable cells were counted after trypan blue staining. (B) The adherent cells (both viable and dead) were also counted. Data are shown as the mean ± SD for triplicate samples. *, P < 0.05 compared with the untreated control (None, No inhibitor). (C) The cells were stained with SYBR green II (green; nuclei) together with Alexa Fluor 594-conjugated phalloidin (red; actin filaments). Bar = 10 μm.