Tumor Necrosis Factor-alpha Induces Cell Type and Tissue-specific Expression of Chemoattractant Cytokines in Vivo

Recombinant murine tumor necrosis factor-alpha (TNF-alpha) was shown to be a strong, systemic stimulus in vivo for members of the chemoattractant cytokine gene families (JE, KC, IP-10). The three genes showed differential sensitivity to TNF-alpha, and their expression demonstrated differential tissue specificity. IP-10 was the most strongly induced messenger RNA and was seen in the liver, kidney, and spleen but very poorly in the lung or skin. JE exhibited a similar pattern, though the magnitude of expression was markedly lower. KC expression was seen only in the liver of TNF-alpha-treated mice. The time course of expression for IP-10 was rapid and transient and showed strong dose dependence. In mice treated with TNF-alpha intravenously, messenger RNA was localized in the splenic stroma but not in adherent macrophages or nonadherent lymphocytes. In situ hybridization found the majority of intercrime expression in the splenic red pulp with little or no expression seen in the white pulp. In vitro, TNF-alpha was a potent stimulus of chemoattractant messenger RNA expression in fibroblasts but not in inflammatory peritoneal macrophages. These results indicate that TNF-alpha may be an important stimulus for chemoattractant cytokine gene expression in vivo, and the primary cell types responsible may be either stromal fibroblasts, microvascular endothelium, and/or a subset of anchored mononuclear phagocytes.