LTD₄ augments TNF release in vivo and in vitro

In vivo data suggest a role of LTD₄ in mediating endotoxin (LPS)-inducible liver injury in galactosamine-sensitized mice. Leukotriene D₄ (LTD₄) was shown to synergize in this model with subtoxic amounts of LPS in inducing hepatitis. Mice challenged i.v. with a subtoxic dose of LPS [50 ng/kg] showed significant TNF serum levels 90 min later which were sixfold increased by coadministration of 50 μg/kg LTD₄. When rat Kupffer cells were challenged with LPS, TNF-α measured in the supernatant was significantly increased by LTD₄ [100 pg-100 ng/ml]. Addition of LTD₄ alone did not result in any detectable TNF formation. Since Kupffer cells are known producers of small amounts of LTD₄, it seems feasible that LTD₄ represents an autocrine stimulus of nonparenchymal liver cells. In fact, different LTD₄ synthesis inhibitors and receptor antagonists attenuated LPS-inducible TNF release of rat Kupffer cells supporting the conclusion that LTD₄ acts as an endogenous autocrine enhancer of liver macrophage TNF release.