Inhibition of IRF5 hyperactivation protects from lupus onset and severity
Su Song, … , William L. Clapp, Betsy J. Barnes
Su Song, … , William L. Clapp, Betsy J. Barnes
Published September 8, 2020
Citation Information: J Clin Invest. 2020;130(12):6700-6717. https://doi.org/10.1172/JCI120288.
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Research Article Autoimmunity Immunology

Inhibition of IRF5 hyperactivation protects from lupus onset and severity

Abstract

The transcription factor IFN regulatory factor 5 (IRF5) is a central mediator of innate and adaptive immunity. Genetic variations within IRF5 are associated with a risk of systemic lupus erythematosus (SLE), and mice lacking Irf5 are protected from lupus onset and severity, but how IRF5 functions in the context of SLE disease progression remains unclear. Using the NZB/W F1 model of murine lupus, we show that murine IRF5 becomes hyperactivated before clinical onset. In patients with SLE, IRF5 hyperactivation correlated with dsDNA titers. To test whether IRF5 hyperactivation is a targetable function, we developed inhibitors that are cell permeable, nontoxic, and selectively bind to the inactive IRF5 monomer. Preclinical treatment of NZB/W F1 mice with an inhibitor attenuated lupus pathology by reducing serum antinuclear autoantibodies, dsDNA titers, and the number of circulating plasma cells, which alleviated kidney pathology and improved survival. Clinical treatment of MRL/lpr and pristane-induced lupus mice with an inhibitor led to significant reductions in dsDNA levels and improved survival. In ex vivo human studies, the inhibitor blocked SLE serum–induced IRF5 activation and reversed basal IRF5 hyperactivation in SLE immune cells. We believe this study provides the first in vivo clinical support for treating patients with SLE with an IRF5 inhibitor.

Authors

Su Song, Saurav De, Victoria Nelson, Samin Chopra, Margaret LaPan, Kyle Kampta, Shan Sun, Mingzhu He, Cherrie D. Thompson, Dan Li, Tiffany Shih, Natalie Tan, Yousef Al-Abed, Eugenio Capitle, Cynthia Aranow, Meggan Mackay, William L. Clapp, Betsy J. Barnes

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Figure 4

IRF5 peptide inhibitors readily enter primary immune cells to inhibit R848-induced IRF5 nuclear translocation.

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IRF5 peptide inhibitors readily enter primary immune cells to inhibit R8...
(A) Representative flow cytometry histograms showing uptake of 10 μM FITC-conjugated PTD or N5-1 after incubation of human PBMCs with an inhibitor for 1 hour. For inhibitor uptake, an FITC intensity of greater than 104 in CD14+ monocytes (light gray) and 103 in CD19+ B cells (dark gray) was considered positive. (B) Percentage of total monocytes and B cells positive for FITC-conjugated N5-1. n = 4 independent samples from healthy donors. (C) Representative images of cellular uptake of 10 μM FITC-conjugated PTD or N5-1 in monocytes (top row), B cells (bottom row), and pDCs (bottom panel). Inhib, inhibitor. (D) Representative images of IRF5 cellular localization in monocytes (CD14) and B cells (CD19) after preincubation of PBMCs with 10 μM mock, PTD, N5-1, or C5-2 inhibitors followed by stimulation with 500 ng/mL R848 for 2 hours. (E and F) Quantification of IRF5 nuclear translocation in monocytes (E) and B cells (F) was done by imaging flow cytometry. n = 6 independent samples from healthy donors. (G) Representative Western blot of nuclear extracts from primary human monocytes following treatment with 2.5 μM mock, PTD, N5-1, or C5-2 inhibitors and stimulation with 500 ng/mL R848 for 2 hours. (H) Quantification of nuclear IRF5 from G relative to lamin B1. n = 3 independent samples from healthy donors. Data are representative of 3 or more independent experimental replicates. Data represent the meant ± SEM. **P ≤ 0.01 and ***P ≤ 0.001, by 1-way ANOVA.