microRNA-92a promotes CNS autoimmunity by modulating the regulatory and inflammatory T cell balance
Mai Fujiwara, Radhika Raheja, Lucien P. Garo, Amrendra K. Ajay, Ryoko Kadowaki-Saga, Sukrut H. Karandikar, Galina Gabriely, Rajesh Krishnan, Vanessa Beynon, Anu Paul, Amee Patel, Shrishti Saxena, Dan Hu, Brian C. Healy, Tanuja Chitnis, Roopali Gandhi, Howard L. Weiner, Gopal Murugaiyan
Mai Fujiwara, Radhika Raheja, Lucien P. Garo, Amrendra K. Ajay, Ryoko Kadowaki-Saga, Sukrut H. Karandikar, Galina Gabriely, Rajesh Krishnan, Vanessa Beynon, Anu Paul, Amee Patel, Shrishti Saxena, Dan Hu, Brian C. Healy, Tanuja Chitnis, Roopali Gandhi, Howard L. Weiner, Gopal Murugaiyan
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Research Article Autoimmunity Inflammation

microRNA-92a promotes CNS autoimmunity by modulating the regulatory and inflammatory T cell balance

Abstract

A disequilibrium between immunosuppressive Tregs and inflammatory IL-17–producing Th17 cells is a hallmark of autoimmune diseases, including multiple sclerosis (MS). However, the molecular mechanisms underlying the Treg and Th17 imbalance in CNS autoimmunity remain largely unclear. Identifying the factors that drive this imbalance is of high clinical interest. Here, we report a major disease-promoting role for microRNA-92a (miR-92a) in CNS autoimmunity. miR-92a was elevated in experimental autoimmune encephalomyelitis (EAE), and its loss attenuated EAE. Mechanistically, miR-92a mediated EAE susceptibility in a T cell–intrinsic manner by restricting Treg induction and suppressive capacity, while supporting Th17 responses, by directly repressing the transcription factor Foxo1. Although miR-92a did not directly alter Th1 differentiation, it appeared to indirectly promote Th1 cells by inhibiting Treg responses. Correspondingly, miR-92a inhibitor therapy ameliorated EAE by concomitantly boosting Treg responses and dampening inflammatory T cell responses. Analogous to our findings in mice, miR-92a was elevated in CD4+ T cells from patients with MS, and miR-92a silencing in patients’ T cells promoted Treg development but limited Th17 differentiation. Together, our results demonstrate that miR-92a drives CNS autoimmunity by sustaining the Treg/Th17 imbalance and implicate miR-92a as a potential therapeutic target for MS.

Authors

Mai Fujiwara, Radhika Raheja, Lucien P. Garo, Amrendra K. Ajay, Ryoko Kadowaki-Saga, Sukrut H. Karandikar, Galina Gabriely, Rajesh Krishnan, Vanessa Beynon, Anu Paul, Amee Patel, Shrishti Saxena, Dan Hu, Brian C. Healy, Tanuja Chitnis, Roopali Gandhi, Howard L. Weiner, Gopal Murugaiyan

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Figure 2

T cell–intrinsic miR-92a promotes EAE.

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T cell–intrinsic miR-92a promotes EAE. (A) Frequency of CD11c+ splenic D...
(A) Frequency of CD11c+ splenic DCs from WT and Mir92a–/– mice at EAE onset (n = 5). (B and C) Representative flow cytometric histograms (B) and the MFI values (C) for MHC-II, CD80, CD86, and CD40 in DCs from these EAE mice (n = 4–5). MFIs are represented as the fold change relative to WT conditions. (D) qPCR analyses of Th-polarizing cytokines in DCs isolated from these EAE mice (n = 6–9). (E–G) Representative flow cytometric plots and frequencies of IFN-γ-YFP+ (n = 3) (E), IL-17A-GFP+ (n = 5) (F), and Foxp3-GFP+ (n = 7) (G) cells in WT naive CD4+ T cells cocultured with WT or Mir92a–/– DCs. (H) Adoptive transfer schematic. Total CD4+ T cells from WT and Mir92a–/– mice were transferred into Rag1–/– recipient mice, which were then immunized and monitored for EAE. Created with BioRender.com. (I) Clinical EAE scores of Rag1–/– recipient mice (n = 8–9) in (H). (J) Representative flow cytometric plots and frequencies of IFN-γ+ cells in Th1-polarized WT and Mir92a–/– naive CD4+ T cells (n = 6). (K and L) Representative flow cytometric plots and frequencies of IL-17A+ cells and qPCR analysis of Rorc expression in nonpathogenic Th17-polarized (n = 6–7) (K) or pathogenic Th17-polarized (n = 4) (L) WT and Mir92a–/– naive CD4+ T cells. (M) Representative flow cytometric plots and frequencies of Foxp3+ cells in Treg-polarized WT and Mir92a–/– naive CD4+ T cells (n = 4). Data are representative of 2–3 independent experiments and indicate the mean ± SEM. *P < 0.05 and ***P < 0.001, by unpaired, 2-tailed Student’s t test (A, E–G, and J–M), 1-way ANOVA with Šidák’s multiple-comparison test between WT and Mir92a–/– mice within each condition (C and D), or Mann-Whitney U test (I).