Differential regulation of cytokine and cytokine receptor mRNA expression upon infection of bone marrow-derived macrophages with Listeria monocytogenes

Cytokine and cytokine receptor mRNA expression was analyzed by PCR-assisted amplification of RNA extracted from bone marrow-derived macrophages (BMMphi) at different time points after infection with Listeria monocytogenes. The mRNAs for the cytokines interleukin-1alpha (IL-1alpha), IL-1beta, and tumor necrosis factor alpha (TNF-alpha) were induced early after infection, whereas IL-6 mRNA appeared later and even nonhemolytic Listeria strains, which are unable to grow inside eukaryotic cells, induced the same cytokine mRNAs at levels similar to those of the wild-type strain. In most cases, the amounts of cytokines determined by various bioassays correlated with the level of mRNA induction. Inhibition of phagocytic uptake of L. monocytogenes by cytochalasin D treatment resulted in adherent bacteria which still induced the proinflammatory cytokines. In BMMphi, the level of IL-1 receptor II mRNA was unaffected, whereas mRNA expression of the two subtypes of tumor necrosis factor receptors (TNF-RI and TNF-RII) was differentially regulated upon infection: transcription of TNF-RI was reduced, and that of TNF-RII mRNA was induced. Similar to the decreased TNF-RI mRNA expression, gamma interferon receptor mRNA was downregulated in L. monocytogenes-infected BMMphi. This dose- and time-dependent induction or downregulation of cytokine receptor mRNA following L. monocytogenes infection of BMMphi was not observed upon infection of established macrophage-like cell lines J774 and P388D1. Induction of IL-6 mRNA as well as IL-1alpha/beta and TNF-alpha mRNAs upon L. monocytogenes infection of BMMphi occurs independently of autocrine TNF-alpha signaling via TNF-RI or TNF-RII, as shown by infection of TNF-RI- and TNF-RII-deficient macrophages derived from mutant B6x129 mice. In contrast to gamma interferon receptor mRNA, both TNF receptor subtype mRNAs were not influenced by L. monocytogenes infection of hybrid (B6x129) mouse macrophages