Polycomb repressive complex 2 is a critical mediator of allergic inflammation
Christine R. Keenan, Nadia Iannarella, Alexandra L. Garnham, Alexandra C. Brown, Richard Y. Kim, Jay C. Horvat, Philip M. Hansbro, Stephen L. Nutt, Rhys S. Allan
Christine R. Keenan, Nadia Iannarella, Alexandra L. Garnham, Alexandra C. Brown, Richard Y. Kim, Jay C. Horvat, Philip M. Hansbro, Stephen L. Nutt, Rhys S. Allan
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Research Article Immunology Inflammation

Polycomb repressive complex 2 is a critical mediator of allergic inflammation

Abstract

Strategies that intervene with the development of immune-mediated diseases are urgently needed, as current treatments mostly focus on alleviating symptoms rather than reversing the disease. Targeting enzymes involved in epigenetic modifications to chromatin represents an alternative strategy that has the potential to perturb the function of the lymphocytes that drive the immune response. Here, we report that 2 major epigenetic silencing pathways are increased after T cell activation. By specific inactivation of these molecules in the T cell compartment in vivo, we demonstrate that the polycomb repressive complex 2 (PRC2) is essential for the generation of allergic responses. Furthermore, we show that small-molecule inhibition of the PRC2 methyltransferase, enhancer of zeste homolog 2 (Ezh2), reduces allergic inflammation in mice. Therefore, by systematically surveying the pathways involved in epigenetic gene silencing we have identified Ezh2 as a target for the suppression of allergic disease.

Authors

Christine R. Keenan, Nadia Iannarella, Alexandra L. Garnham, Alexandra C. Brown, Richard Y. Kim, Jay C. Horvat, Philip M. Hansbro, Stephen L. Nutt, Rhys S. Allan

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Figure 5

Small-molecule inhibition of Ezh2 suppresses the development of allergic inflammation.

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Small-molecule inhibition of Ezh2 suppresses the development of allergic...
(A) Effect of Ezh2 inhibitor GSK126 on survival of activated C57BL/6 mouse CD4+ T cells after 3 days in vitro. Data are shown as the mean percentage of the vehicle control cell number ±SEM from 3–5 measurements at each concentration of GSK126. (B) H3K27me3 levels in activated C57BL/6 mouse CD4+ T cells (as in A) after 44 hours. Representative histograms are shown together with median fluorescence intensity (MFI) from n = 3 mice. Data were analyzed by 2-way ANOVA with Holm-Sidak post hoc test. (C) Experimental protocol of GSK126 administration by oral gavage in OVA-induced allergic inflammation. (D) Quantification of flow cytometric analysis of bronchoalveolar lavage infiltrate following GSK126 administration in OVA model of allergic inflammation in C57BL/6 mice (n = 4 per group). Mean and SEM together with individual data points are shown. Statistical analysis by Kruskal-Wallis H test with Dunn’s post hoc test. (E) Representative histological analysis (representative of n = 8 per group, pooled from 2 independent experiments) of the airways of mice treated with GSK126 or vehicle control in OVA model as per C. Scale bars: 100 μm. (F) Quantification of histological analysis showing the frequency of PAS+ cells and the inflammation score. Mean and SEM together with individual data points are shown for n = 8 per group. Statistical significance was determined by Student’s t test. (G) OVA-specific IgE and total IgE detected in serum of mice following OVA challenge and GSK126 administration. Mean and SEM are shown for n = 5 (vehicle), n = 4 (each GSK dose). Statistical analysis by Kruskal-Wallis H test with Dunn’s post hoc test. (H) Airway resistance (Rn) following OVA-induced allergic inflammation in C57BL/6 mice treated with vehicle or GSK126. Full methacholine dose-response for vehicle- and GSK126-treated (150 mg/kg) groups is shown in the left panel and all groups’ airway resistance to 10 mg/ml methacholine is shown in the right panel. Mean and SEM together with individual data points are shown for n = 6 (saline/vehicle), n = 6 (OVA/vehicle), n = 5 (OVA/75 mg/kg GSK126), n = 5 (OVA/150 mg/kg GSK126). Data were analyzed by 2-way ANOVA with Bonferroni’s post hoc test. **P < 0.01 with specific comparisons denoted in right-hand panel.