PR-39, a porcine antimicrobial peptide, inhibits apoptosis: involvement of caspase-3.

The porcine antimicrobial peptide, PR-39, has several activities beyond its function of killing bacteria. Here we report that PR-39 alters macrophage viability by inhibiting apoptosis, which was induced by nutrient depletion, LPS stimulation or camptothecin treatment. This antiapoptotic effect was pronounced resulting in significant reductions in annexin-V binding to externalized phosphatidylserine and was associated with a decrease in caspase-3 activity. These findings suggest that PR-39, a porcine neutrophil-derived antimicrobial peptide, might function in the inflammatory milieu not only to kill bacteria, but also to aid in modulating the viability of inflammatory cells by regulating apoptosis.