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.