Efficient suilysin-mediated invasion and apoptosis in porcine respiratory epithelial cells after streptococcal infection under air-liquid interface conditions

Meng, Fandan; Wu, Nai-Huei; Seitz, Maren; Herrler, Georg; Valentin-Weigand, Peter

Scientific RepoRts | 6:26748 | DOI: 10.1038/srep26748 the cleaved form of caspase-3 in PBEC, which is considered as a major enzyme regulating apoptosis 44 . As shown in Fig. 6 , the number of cells positive for cleaved caspase-3 (in red) were most abundant in PBEC infected by wt and cS148 S. suis. Most of the stained cells were located at the edge of areas where the epithelial cell layer had been damaged and cells had detached as a consequence of infection. Cells positive for capase-3 showed further signs of apoptosis such as chromatin condensation and apoptotic bodies. Furthermore, the wt strain and strain cS148 clearly colocalized with caspase-3 positive cells of PBEC. In contrast, only few cells were stained for cleaved caspase-3 in PBEC infected with the suilysin-deficient mutant 10Δ sly and strain cW461F, no colocalization of caspase-3 with bacteria was observed (Fig. 6A ).