Effect of probiotics on the viability of porcine and human neutrophils in vitro

Lactobacillus, Bifidobacterium and Enterococcus cultures are increasingly used as probiotics for humans and pigs. The aim of this study was to investigate if co-cultivation of porcine and human neutrophils with probiotics can lead to increased apoptosis in vitro. Ten adult Large white pigs and 10 healthy human donors were used in this study. Neutrophils were isolated by dextran sedimentation and cultivated with and without the lactic acid bacteria Bifidobacterium bifidum, Lactobacillus rhamnosus, and Enterococcus faecium for 2, 4, 24 and 48 h. Early and late apoptosis was measured using flow cytometry, and cell lysis was detected based on lactate dehydrogenase activity (LDH). A significant (P < 0.05; P < 0.01) increase in apoptotic neutrophils and LDH was observed at 24 h and 48 h in vitro. All probiotics exerted their greatest effects on the early apoptosis of porcine neutrophils, while the effects of L. rhamnosus were most pronounced on late apoptosis and those of B. bifidum on LDH release of human neutrophils. The increased neutrophil apoptosis caused by probiotic bacteria can be beneficial for more efficient efferocytosis and faster resolution of inflammation and tissue regeneration. In conclusion, we have demonstrated that the interaction of B. bifidum, L. rhamnosus, and E. faecium with human and porcine neutrophils leads to their apoptosis.