Bacterial Genomic DNA Mediated Phagocytosis of Apoptotic Neutrophils by Macrophages without Provoking Inflammation - Abstract
The bacterial genomic DNA from antibiotics killed bacteria may have unique functions in the pathogenesis of bacterial infectious diseases. We investigate the ability of macrophages to engulf the apoptotic neutrophils mediated by bacterial genomic DNA (B-DNA). We found that the percentage of macrophages with ingested apoptotic neutrophils was increased after 2µg/ml B-DNA stimulation. The enhancement was consistent with cell surface and total TLR9 expression on macrophages. B-DNA had no significant effect on the secretion of IL-6 and TNF-? from macrophages after B-DNA stimulation and ingestion of apoptotic neutrophils. We proposed that bacterial genomic DNA released from the antibiotic killed bacteria could mediate phagocytosis of apoptotic neutrophils by macrophages through TLR-9 signaling pathway in bacterial infectious diseases without provoking inflammation, which is one important process of the immune system and is necessary for the homeostatic maintenance.