Biological activities of bacterial lipopolysaccharides

skin reaction in mice in vivo and production of tissue factor by macrophages in vitro.

Abstract

A single intradermal injection of bacterial lipopolysaccharide (LPS) caused hemorrhagic necrosis in mouse skin (skin reaction). A tissue factor, membrane glycoprotein, is known to activate the extrinsic blood coagulation cascade. In this study, an attempt was made to compare the structural requirements of LPS to induce skin reaction in vivo, and to produce tissue factor by peritoneal macrophages in vitro. The skin reaction was induced by injection of a smooth type (S)-LPS, rough type (R: Ra-Re)-LPS, and lipid A derived from Salmonella typhimurium, Salmonella minnesota and Escherichia coli in a dose-dependent manner, but not by the polysaccha-ride portion of S-LPS. Re-LPS induced the strongest dermal inflammation (activation) in ddY mice. This was followed by Rc-LPS, lipid A (the activity of Rc-LPS was similar to lipid A), Ra-LPS and S-LPS in the order mentioned. In the C3H/HeN mice, Re-LPS and lipid A induced the skin reaction to almost the same levels as in the ddY mice. The activity of synthetic E.coκtype lipid A (#506) which has a double acyl structure was similar to or sHghtly weaker than that by natural lipid A, whereas the activity of a synthetic counterpart of a Iipid A precursor (#406) was considerably weak. In the C3H/HeJ mice, Re-LPS and lipid A did not induce any hemorrhagic response. The macrophage suspension of C3H/HeN mice was stimulated with Re-LPS at 37℃ for 6 hours, and the sonic lysate of the cells was used to estimate the tissue factor activity by the clotting method using a fibrometer. The tissue factor was produced by Re-LPS in ddY and C3H/HeN mouse macrophages. The activity of #406 was the same as that of #506. C3H/HeJ macrophages did not respond to even a high dose of Re-LPS. These results indicate that the lipid A portion of LPS is very important to cause a reaction both in viro. As to the lipid A structure, the double acyl structure is not required for the production of tissue factor by macrophages, but is required for the induction of skin reaction.