Regulation by Endogenous Interferon of Virus-Induced Cytokine Gene Expression in Mouse Macrophages

Abstract

In macrophages from inbred mice the magnitude of the interferon (IFN) response to Newcastle disease virus (NDV) infection is under genetic control of the locus If-1, with C57BL/6 carrying the ‘high-producer’ allele If-l^h whereas BALB/c have the ‘low-producer’ allele If-1¹. The IFN produced consists of 90% IFN-β and there are 10-fold differences between macrophages from If-l^h and If-1¹ mice. Recently, we observed that interleukin-6 (IL-6) is coinduced by NDV in macrophages and seems to be under the same genetic control. Noninduced macrophages have been shown to secrete low amounts of antiviral activity endogenously when cultured in the presence of the macrophage-colony-stimulating factor (M-CSF). Here, we report that the amount of this endogenous IFN varies between macrophages from different mouse strains. Macrophages from BALB/c were found to secrete 5–10 times more endogenous IFN compared to C57BL/6. The antiviral activity could be identified as IFN-β. Interestingly, we observed that endogenous IFN specifically down-regulates NDV-induced IFN and IL-6 production. Preculture of BALB/c macrophages in M-CSF plus anti-IFN-β to neutralize the biological effects of the endogenous IFN provoked a 30- to 50-fold increase in NDV-induced cytokine production, resulting in a nearly complete abrogation of the genetically determined difference since the same treatment only caused a 6-fold increase in C57BL/6 macrophages following NDV infection. This increase in cytokine gene expression was specific for NDV and marked by a strong additional activation of IFN-α genes. Addition of mouse recombinant IFN-α₄ to anti-IFN-β-treated macrophages for 18 h prior to NDV infection down-regulated again IFN gene expression and reestablished the genetic differences between macrophages from If-l^h and If-1¹ mice. Studies using macrophages from B6.C-H28^C congenic mice, carrying the histocompatibility locus H-28 and the If-1¹ locus from BALB/c on a C57BL/6 background, gave identical results as with BALB/c macrophages. These data indicate that the two alleles If-l^h and If-1¹ may harbor IFN-inducible genes responding differently to IFN and specifically suppressing subsequent IFN and IL-6 gene expression after stimulation by NDV.

Differential Regulation of TLR-Dependent MyD88 and TRIF Signaling Pathways by Free Zinc Ions

“…The cells were grown for 3-4 d under normal culture conditions until confluency and cultured for 3 more days in serum-free medium (21). Supernatants were collected, sterile-filtered, and concentrated (Minicon B15 clinical sample concentrator; Millipore).…”

Restricted and Selective Tropism of a Venezuelan Equine Encephalitis Virus-Derived Replicon Vector for Human Dendritic Cells

“…It has been reported that M-CSF can induce the expression of antiviral factors such as interferons (54,55) in monocytes. Thus, we also evaluated in vitro-generated macrophages derived from adherent monocytes cultured in the presence of 10% human AB serum for 2 d. These cells were transduced with VRP-EGFP (MOI of 10) and analyzed 24 h later for fluorescent protein expression.…”

Interferon-Induced Expression ofIf-1handIf-llAlleles in Newcastle Disease Virus-Infected Mouse Macrophages Is Associated with Specific Differences in Viral Gene Transcription

“…amount of interleukin-6 (IL-6)'12' and tumor necrosis factor-a (TNF-a)'13' produced by NDV-infected macrophages. Moreover, the activity of //-/ alíeles in macrophages is differentially regulated in an autocrine manner by the endogenous IFNß (12,14) jn tne present study, we have further characterized the functions of If-1 and obtained evidence for its involvement in the inhibition of NDV transcription.…”