Activation of mitogen-activated protein kinases is involved in the induction of interferon β gene in macrophages infected with Orientia tsutsugamushi

Abstract

We investigated the role of MAPK in IFN-β gene expression in macrophages after infection with Orientia tsutsugamushi. ERK1/2 became phosphorylated in Orientia-stimulated macrophages. Selective inhibition of ERK1/2 and p38 MAPK could all significantly reduce Orientia-stimulated IFN-β mRNA expression. Orientia inactivation by heat abolished IFN-β mRNA induction only, whereas cytochalasin D treatment completely blocked both IFN-β and chemokine expression, suggesting requirement of cellular internalization by viable bacteria for IFN-β gene induction. In conclusion, our data indicate that MAPK pathways are required to induce maximal IFN-β gene expression in macrophages during Orientia infection. © 2008 The Societies and Blackwell Publishing Asia Pty Ltd.