The Transcription Factor STAT-1 Couples Macrophage Synthesis of 25-Hydroxycholesterol to the Interferon Antiviral Response

Abstract

SummaryRecent studies suggest that the sterol metabolic network participates in the interferon (IFN) antiviral response. However, the molecular mechanisms linking IFN with the sterol network and the identity of sterol mediators remain unknown. Here we report a cellular antiviral role for macrophage production of 25-hydroxycholesterol (cholest-5-en-3β,25-diol, 25HC) as a component of the sterol metabolic network linked to the IFN response via Stat1. By utilizing quantitative metabolome profiling of all naturally occurring oxysterols upon infection or IFN-stimulation, we reveal 25HC as the only macrophage-synthesized and -secreted oxysterol. We show that 25HC can act at multiple levels as a potent paracrine inhibitor of viral infection for a broad range of viruses. We also demonstrate, using transcriptional regulatory-network analyses, genetic interventions and chromatin immunoprecipitation experiments that Stat1 directly coupled Ch25h regulation to IFN in macrophages. Our studies describe a physiological role for 25HC as a sterol-lipid effector of an innate immune pathway.

25-Hydroxycholesterol Activates the Integrated Stress Response to Reprogram Transcription and Translation in Macrophages

“…Although two recent independent studies demonstrated the broad antiviral activity of 25OHC, the mechanism by which 25OHC suppresses viral infection is still unclear (11,12,59). We demonstrate that 25OHC significantly alters important plasma membrane lipid species and activates the ISR, both of which may contribute to the antiviral activity of 25OHC.…”

“…MCMV Infection Stimulates 25OHC Production and Induces Stress Response Gene Transcription-Ch25h is an interferonstimulated gene, and two recent independent publications demonstrated that CH25H and its product 25OHC have broad antiviral activity (11,12). To determine whether the concentrations of 25OHC produced during viral infections were capable of inducing ISR genes, we infected BMDMs with MCMV.…”

“…Mice lacking Ch25h exhibit abnormal immunoglobulin A production by B lymphocytes (6) and dysfunctional B cell migration within follicles (10). Recent studies demonstrated a broad and potent antiviral activity of CH25H and 25OHC (11,12) and suggested that 25OHC impedes viral infection at multiple stages.…”

ATF3 Is a Key Regulator of Macrophage IFN Responses

“…25-Hydroxycholesterol (25-HC) is an oxysterol that displays potent antiviral activity (44,45). Additionally, Ch25h, the gene encoding cholesterol 25-hydroxylase, which controls the production of 25-HC, is classified as an ISG (46).…”

“…Cholesterol 25-hydroxylase (encoded by Ch25h) catalyzes the formation of 25-HC during cholesterol metabolism, and ATF3 was previously found to directly regulate Ch25h expression (47). Additionally, separate studies have characterized Ch25h as an ISG, and 25-HC has been shown to elicit broad antiviral functions (44,45). In this study, we show, to our knowledge for the first time, that ATF3 can regulate the expression of Ch25h following IFN signaling, a mechanism that is likely important for maintaining an appropriate immune response to viruses.…”