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 5

N5-1 protects NZB/W mice from spontaneous onset of lupus.

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N5-1 protects NZB/W mice from spontaneous onset of lupus. (A) Representa...
(A) Representative Western blot of nuclear extracts from RAW264.7 macrophages pretreated for 1 hour with N5-1 followed by LPS for 2 hours. Noncultured cells, 0 hours before pretreatment; cultured cells, 3 hours after treatment. (B) Quantification of nuclear IRF5 in A relative to lamin B1 from 3 independent replicates. Statistical significance was determined by 1-way ANOVA. (C) In vivo inhibition of IL-6 secretion by N5-1 in WT (Irf5+/+), heterozygous (Het) (Irf5+/–), and KO (Irf5–/–) mice. Sera were harvested 1.5 hours after R848 administration. n = 3–4 mice/group. Statistical significance was determined by 1-way ANOVA. (D) N5-1 dosing strategy for NZB/W F1 mice. (E) Anti-dsDNA Ig titers (1:500 serum dilution) in mice at 20 weeks of age. (F) ANA immunofluorescence scoring for sera from 11 PBS- and 10 N5-1–treated mice. 0, negative signal; 4, strongest signal. Statistical significance was determined by Mann-Whitney U test. (G) Representative ANA images from 27-week-old treated mice (×20 objective and ×10 eyepiece). (H and I) Percentage of circulating IgD–B220CD138+ PCs (H) and B220+CD11c+CD11b+ ABCs (I). n = 4 mice/time point. Statistical significance was determined by 2-way ANOVA and Bonferroni’s multiple-comparison test. (H) F(7,35) = 10.27, P < 0.0001, age; F(1,35) = 4.125, P = 0.049, treatment; F(7,35) = 1.627, P = 0.1603, interaction. *P = 0.0133 vs. PBS, week 38; ††P < 0.0081 and ††††P < 0.0001 vs. PBS, week 14. (I) F(5,32) = 20.63, P < 0.0001, age; F(1,32) = 4.402, P = 0.0439, treatment; F(5,32) = 4.146, P = 0.0051, interaction. ***P = 0.0001 versus PBS, week 35; ††P = 0.0033, †††P = 0.0002 and ††††P < 0.0001 vs. PBS, week 14; ##P = 0.0005 and ###P = 0.0029 vs. N5-1, week 14. (J and K) Inhibition by N5-1 of IRF5 activation in cohort 2 (14–21 weeks old). CD11b+ monocytes (J) and B220+ (K) B cells. n = 4 mice/group. Statistical significance was determined by 1-way ANOVA. Data represent the mean ± SEM. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, and ****P ≤ 0.0001.