Bacterial lipopolysaccharide (LPS) plays a major role in stimulating the synthesis and release of the principal osteoclast-activating cytokines, namely, interleukin 1 and tumor necrosis factor-α from immune cells. Although monocytes/macrophages are the main producers of these cytokines, recent evidence has indicated that polymorphonuclear leukocytes (PMN) have the ability to release IL-1 and TNF-α . Calcium hydroxide has been shown to be an effective medicament in root canal infections, reducing the microbial titre within the canal. It has been proposed that the therapeutic effect of Ca(OH)2 may also be the result of direct inactivation of LPS. The purpose of this study was to investigate whether treatment of Porphyromonas endodontalis LPS with calcium hydroxide alters its biological action as measured by human PMN secretion of IL-1 and TNF-α , and it was compared with Escherichia coli LPS.P. endodontalis ATCC 35406 was cultured in anaerobic condition, and LPS was extracted using the hot-phenol water extraction method and purified. Purchased E. coli LPS was also purified. 100 μ g/ml of each LPS in pyrogen free water were incubated with 25mg/ml Ca(OH)2 at 37℃ for 7 days. The supernatants were subjected to ultrafiltration, and the isolates were lyophilized and weighed. PMNs were obtained from peripheral blood by centrifugation layered over Lymphoprep. The cells were resuspended (4×10 6 cells/ml) in RPMI 1640 followed by treatment with various concentrations of LPS (0, 0.1, 1, 10 μ g/ml) for 24 hours at 37℃ in 5% CO2 incubator. The supernatants of cells were collected and the levels of IL-1α , IL-1βand TNF-αwere measured by enzyme-linked immunosorbent assay.The results were as follows; 1. The levels of IL-1α , IL-1β , TNF-αfrom PMN treated with each LPS were significantly higher than those released from unstimulated PMN of the control group (p<0.05). 2. The levels of all three cytokines released from PMN stimulated with each calcium hydroxide treated LPS were significantly lower than those released from PMN stimulated with each untreated LPS (p<0.05), while they were not significantly different from those released from unstimulated ABSTRACT ※이 연구는 삼성생명과학연구소 연구비(C-A2-3101)의 보조로 이루어졌음.
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