Functional role of interleukin 1 in periodontal disease: induction of interleukin 1 production by Bacteroides gingivalis lipopolysaccharide in peritoneal macrophages from C3H/HeN and C3H/HeJ mice

Abstract

Hot phenol-water-extracted lipopolysaccharide (LPS) from Bacteroides gingivalis 381 was purified by Sephadex G-100 chromatography with Tris buffer supplemented with sodium deoxycholate and EDTA (B-LPS). In the present study, B-LPS was examined for its ability to induce interleukin 1 (IL-1) production, a mitogenic response, and macrophage activation in LPS high-responder C3H/HeN and low-responder C3H/HeJ mice. A significant increase in IL-1 production was observed in C3H/HeN and C3H/HeJ peritoneal macrophages treated with various doses (1.0 to 50 micrograms/ml) of B-LPS. IL-1 production by C3H/HeN macrophages treated with B-LPS (10 micrograms/ml) was about seven times greater than that by C3H/HeJ macrophages. However, the IL-1 production induced by B-LPS (10 micrograms/ml) in C3H/HeN macrophages was four times lower compared with that induced by Escherichia coli O111 B4 LPS. Also, a significant increase in IL-1 production was found in human monocytes stimulated with B-LPS. That B-LPS-induced IL-1 exhibits some molecular weight heterogeneity was indicated from Sephadex G-75 gel filtration profiles. A significant, high mitogenic response by whole spleen cells with 1 X 10(5) to 5 X 10(4) cells of either mouse strain per well treated with B-LPS (10 to 50 micrograms/ml) was observed. However, the response of C3H/HeJ mice was less than that of the C3H/HeN strain. Also, glucose consumption assays indicated that enhanced macrophage activation occurred in C3H/HeN but not in C3H/HeJ mice treated with B-LPS. In light of recent studies showing that IL-1 stimulates bone resorption in a mouse calvaria system and collagenase production in fibroblasts, we suggest that B-LPS-induced IL-1 may play a significant role in the pathogenesis of adult periodontal disease.