IL-23R–activated STAT3/STAT4 is essential for Th1/Th17-mediated CNS autoimmunity
Priscilla W. Lee, … , Michael K. Racke, Amy E. Lovett-Racke
Priscilla W. Lee, … , Michael K. Racke, Amy E. Lovett-Racke
Published September 7, 2017
Citation Information: JCI Insight. 2017;2(17):e91663. https://doi.org/10.1172/jci.insight.91663.
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Research Article Immunology

IL-23R–activated STAT3/STAT4 is essential for Th1/Th17-mediated CNS autoimmunity

Abstract

The factors that promote the differentiation of pathogenic T cells in autoimmune diseases are poorly defined. Use of genetically modified mice has provided insight into molecules necessary for the development of autoimmunity, but the sum of the data has led to contradictory observations based on what is currently known about specific molecules in specific signaling pathways. To define the minimum signals required for development of encephalitogenic T cells that cause CNS autoimmunity, myelin-specific T cells were differentiated with various cytokine cocktails, and pathogenicity was determined by transfer into mice. IL-6+IL-23 or IL-12+IL-23 generated encephalitogenic T cells and recapitulated the essential cytokine signals provided by antigen-presenting cells, and both IL-6 and IL-12 induced IL-23 receptor expression on both mouse and human naive T cells. IL-23 signaled through both STAT3 and STAT4, and disruption in STAT4 signaling impaired CNS autoimmunity independent of IL-12. These data explain why IL-12–deficient mice develop CNS autoimmunity, while STAT4-deficient mice are resistant. CD4+ memory T cells from multiple sclerosis patients had significantly higher levels of p-STAT3/p-STAT4, and p-STAT3/p-STAT4 heterodimers were observed upon IL-23 signaling, suggesting that p-STAT3/p-STAT4 induced by IL-23 signaling orchestrate the generation of pathogenic T cells in CNS autoimmunity, regardless of Th1 or Th17 phenotype.

Authors

Priscilla W. Lee, Alan J. Smith, Yuhong Yang, Amanda J. Selhorst, Yue Liu, Michael K. Racke, Amy E. Lovett-Racke

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Figure 2

The combinations of IL-6+IL-23 or IL-12+IL-23 restore the encephalitogenicity to anti-CD3/CD28–activated T cells.

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The combinations of IL-6+IL-23 or IL-12+IL-23 restore the encephalitogen...
(A) Splenocytes from Vα2.3/Vβ8.2 TCR Tg mice were activated in vitro with anti-CD3/CD28 with or without IL-23 and/or IL-6. At 60 hours, cells were harvested and adoptively transferred into B10.PL mice (5 × 106 cells/mouse). The number of mice with clinical signs/total number of mice in each group in this representative experiment is shown as follows: no cytokine (0/7); IL-23 (0/4); IL-6 (3/7); and IL-6+IL-23 (5/5). (B) Naive CD4+ T cells were purified from Vα2.3/Vβ8.2 Tg splenocytes and activated with anti-CD3/CD28 in the presence of IL-23, IL-6, and/or IL-12. At 60 hours, cells were harvested and adoptively transferred into B10.PL mice (1 × 106 cells per mouse). The number of mice with clinical signs/total number of mice in each group in this representative experiment is shown as follows: IL-23 (0/4); IL-6 (1/5); IL-12 (2/5); IL-6+IL-23 (9/10); and IL-12+IL-23 (10/10). ***P < 0.001 (Mann-Whitney U test). IL-23R expression (gated on CD4+ cells) was analyzed by flow cytometry (C), and supernatants were analyzed by ELISA for IFN-γ (E) and IL-17A (F) (mean ± SEM). (D) Naive CD4+ T cells were purified from B10.PL splenocytes and activated in vitro with anti-CD3/CD28 and IL-23, IL-6, IL-12, or combinations. Cells were collected at 60 hours, and Il23r and Hprt mRNA were detected by real-time PCR. Fold change of gene expression was shown relative to no-cytokine condition (mean ± SEM). (G) Proliferation was determined by 3H-thymidine incorporation of Vα2.3/Vβ8.2 TCR Tg T cells using anti-CD3/CD28 stimulation with IL-6, IL-12, IL-23, or combinations. Each dot represents a replicate well. ***P < 0.001 (1-way ANOVA with Bonferroni’s multiple comparison test). Data is representative of ≥ 3 independent experiments.