The antiviral restriction factor IFN-induced transmembrane protein 3 prevents cytokine-driven CMV pathogenesis
Maria A. Stacey, … , Paul Kellam, Ian R. Humphreys
Maria A. Stacey, … , Paul Kellam, Ian R. Humphreys
Published February 27, 2017
Citation Information: J Clin Invest. 2017;127(4):1463-1474. https://doi.org/10.1172/JCI84889.
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Research Article Immunology Virology

The antiviral restriction factor IFN-induced transmembrane protein 3 prevents cytokine-driven CMV pathogenesis

Abstract

The antiviral restriction factor IFN-induced transmembrane protein 3 (IFITM3) inhibits cell entry of a number of viruses, and genetic diversity within IFITM3 determines susceptibility to viral disease in humans. Here, we used the murine CMV (MCMV) model of infection to determine that IFITM3 limits herpesvirus-associated pathogenesis without directly preventing virus replication. Instead, IFITM3 promoted antiviral cellular immunity through the restriction of virus-induced lymphopenia, apoptosis-independent NK cell death, and loss of T cells. Viral disease in Ifitm3–/– mice was accompanied by elevated production of cytokines, most notably IL-6. IFITM3 inhibited IL-6 production by myeloid cells in response to replicating and nonreplicating virus as well as following stimulation with the TLR ligands Poly(I:C) and CpG. Although IL-6 promoted virus-specific T cell responses, uncontrolled IL-6 expression in Ifitm3–/– mice triggered the loss of NK cells and subsequently impaired control of MCMV replication. Thus, IFITM3 represents a checkpoint regulator of antiviral immunity that controls cytokine production to restrict viral pathogenesis. These data suggest the utility of cytokine-targeting strategies in the treatment of virus-infected individuals with impaired IFITM3 activity.

Authors

Maria A. Stacey, Simon Clare, Mathew Clement, Morgan Marsden, Juneid Abdul-Karim, Leanne Kane, Katherine Harcourt, Cordelia Brandt, Ceri A. Fielding, Sarah E. Smith, Rachael S. Wash, Silvia Gimeno Brias, Gabrielle Stack, George Notley, Emma L. Cambridge, Christopher Isherwood, Anneliese O. Speak, Zoë Johnson, Walter Ferlin, Simon A. Jones, Paul Kellam, Ian R. Humphreys

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Figure 4

IFITM3 suppresses MCMV-induced IL-6 production.

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IFITM3 suppresses MCMV-induced IL-6 production. (A–C) WT and Ifitm3–/– m...
(A–C) WT and Ifitm3–/– mice were infected or not with MCMV. (A) Proinflammatory cytokines were measured by multiplex immunoassay in splenic homogenates 4 days p.i. Data represent the mean ± SEM of 8 to 9 mice per group. (B) Spleens were taken on days 0, 2, and 4 p.i., and IL-6 was measured by ELISA in tissue homogenates. Individual mice ± mean values are depicted, and the data represent at least 2 experiments for each time point. (C) IL-6 expression by (unstimulated ex vivo) CD11chiMHC II+ (cDCs), CD11b–CD11c+B220+Siglec H+ (pDCs), and F4/80+CD11b+ (Macs) was detected by flow cytometry. Data represent the mean ± SEM of expression values for 4 to 5 mice per group from 2 experiments. (D) Mixed WT/Ifitm3–/– bone marrow chimeras were generated and infected with MCMV. After 4 days, IL-6 in spleen supernatants was quantified by ELISA. Data from 1 of 2 experiments are shown. (E) IFITM3 expression by splenic macrophages (Macs), cDCs, and pDCs was assessed by flow cytometry (blue line = WT on day 0, green line = WT on day 2 p.i., red line = Ifitm3–/– on day 2 p.i.). (F) WT and Ifitm3–/– FLT3L-, GM-CSF– and M-CSF–generated myeloid cells and primary MEFs were infected with MCMV (MOI = 1), and IL-6 protein was measured 6 hours later. Data represent the mean ± SEM of 4 quadruplet wells for at least 3 experiments. *P < 0.05, **P < 0.01, and ***P < 0.001, by 2-tailed Students t test (A–C, F) and by 1-way ANOVA with Bonferonni’s multiple comparison post-test analysis (D).