IFN-ε protects primary macrophages against HIV infection
Carley Tasker, Selvakumar Subbian, Pan Gao, Jennifer Couret, Carly Levine, Saleena Ghanny, Patricia Soteropoulos, Xilin Zhao, Nathaniel Landau, Wuyuan Lu, Theresa L. Chang
Carley Tasker, Selvakumar Subbian, Pan Gao, Jennifer Couret, Carly Levine, Saleena Ghanny, Patricia Soteropoulos, Xilin Zhao, Nathaniel Landau, Wuyuan Lu, Theresa L. Chang
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Research Article AIDS/HIV Immunology

IFN-ε protects primary macrophages against HIV infection

Abstract

IFN-ε is a unique type I IFN that is not induced by pattern recognition response elements. IFN-ε is constitutively expressed in mucosal tissues, including the female genital mucosa. Although the direct antiviral activity of IFN-ε was thought to be weak compared with IFN-α, IFN-ε controls Chlamydia muridarum and herpes simplex virus 2 in mice, possibly through modulation of immune response. We show here that IFN-ε induces an antiviral state in human macrophages that blocks HIV-1 replication. IFN-ε had little or no protective effect in activated CD4+ T cells or transformed cell lines unless activated CD4+ T cells were infected with replication-competent HIV-1 at a low MOI. The block to HIV infection of macrophages was maximal after 24 hours of treatment and was reversible. IFN-ε acted on early stages of the HIV life cycle, including viral entry, reverse transcription, and nuclear import. The protection did not appear to operate through known type I IFN-induced HIV host restriction factors, such as APOBEC3A and SAMHD1. IFN-ε–stimulated immune mediators and pathways had the signature of type I IFNs but were distinct from IFN-α in macrophages. IFN-ε induced significant phagocytosis and ROS, which contributed to the block to HIV replication. These findings indicate that IFN-ε induces an antiviral state in macrophages that is mediated by different factors than those induced by IFN-α. Understanding the mechanism of IFN-ε–mediated HIV inhibition through immune modulation has implications for prevention.

Authors

Carley Tasker, Selvakumar Subbian, Pan Gao, Jennifer Couret, Carly Levine, Saleena Ghanny, Patricia Soteropoulos, Xilin Zhao, Nathaniel Landau, Wuyuan Lu, Theresa L. Chang

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Figure 6

IFN-ε induces ROS that protects macrophages against HIV infection.

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IFN-ε induces ROS that protects macrophages against HIV infection. (A) E...
(A) Effect of IFN-α and IFN-ε on genes involved in phagocytosis and ROS production. Intensity maps for expression pattern of genes associated with phagocytosis and ROS generation networks in MDMs in response to IFN-α or IFN-ε for 6 or 24 hours. Red color denotes upregulation, blue color denotes downregulation, and yellow color denotes no significant change or absence of expression; color intensity correlates with expression level. The scale bar ranges from +3 (red) to –3 (blue). The complete list of genes in these networks and their expression levels are shown in Supplemental Table 2. (B) Effect of IFN-ε on phagocytosis and ROS induction. IFN-ε–treated or untreated MDMs were incubated with Texas Red fluorescent E. coli BioParticles, and phagocytic activity was determined by flow cytometry. MDMs with or without IFN-ε treatment for 24 hours were stained with carboxy-H2DCFDA, and the ROS level was determined by flow cytometry. The gate for percentage of positive cells was based on unstained control cells. Results (median, IQR) from different donors are shown. (C) Effect of ROS induction on HIV infection. MDMs were treated with ROS inducers paraquat or plumbagin for 24 hours before infection with HIV-luc (JR-FL). ROS inducers were not added back during infection. *P < 0.05, #P > 0.05, untreated controls vs. treated MDMs. (D) Effect of a ROS inducer on HIV late RT synthesis. MDMs were treated with paraquat or IFN-ε for 24 hours and infected with HIV-luc (VSV-G). The levels of HIV RT DNA products were determined at 24 hours after infection by quantitative real-time PCR. *P < 0.05, treated vs. untreated control. (E) Effect of ROS inhibition on IFN-ε–mediated HIV inhibition. MDMs were treated with or without IFN-ε for 4 hours and were then treated with NAC in the presence of IFN-ε for 2 hours before infection with HIV-luc (JR-FL). IFN-ε and NAC were not added back during the infection. *P < 0.05 IFN-ε–treated MDMs in the presence or absence of NAC. Data in C–E are mean ± SD of triplicate samples. Results in D and E represent 3 independent experiments by by independent-samples t test.