Transcription factor EGR2 controls homing and pathogenicity of TH17 cells in the central nervous system.

CD4+ T helper 17 (TH17) cells protect barrier tissues but also trigger autoimmunity. The mechanisms behind these opposing processes remain unclear. Here, we found that the transcription factor EGR2 controlled the transcriptional program of pathogenic TH17 cells in the central nervous system (CNS) but not that of protective TH17 cells at barrier sites. EGR2 was significantly elevated in myelin-reactive CD4+ T cells from patients with multiple sclerosis and mice with autoimmune neuroinflammation. The EGR2 transcriptional program was intricately woven within the TH17 cell transcriptional regulatory network and showed high interconnectivity with core TH17 cell-specific transcription factors. Mechanistically, EGR2 enhanced TH17 cell differentiation and myeloid cell recruitment to the CNS by upregulating pathogenesis-associated genes and myelomonocytic chemokines. T cell-specific deletion of Egr2 attenuated neuroinflammation without compromising the host’s ability to control infections. Our study shows that EGR2 regulates tissue-specific and disease-specific functions in pathogenic TH17 cells in the CNS. A: mRNA profiles of Th17 cells transduced with empty control retrovirus under non-pathogenic Th17 cell-polarizing conditions (Th17(b): IL-6+TGFb1+aIFN-g+aIL-4), 3 biological replicates; B: mRNA profiles of Th17 cells transduced with Egr2-expressing retrovirus under non-pathogenic Th17 cell-polarizing conditions (Th17(b): IL-6+TGFb1+aIFN-g+aIL-4), 3 biological replicates; C: mRNA profiles of Th17 cells transduced with empty control retrovirus under pathogenic Th17 cell-polarizing conditions in the presence of IL-23 (Th17(23): IL-6+TGFb1+aIFN-g+aIL-4 --> IL-23), 3 biological replicates; D: mRNA profiles of Th17 cells transduced with empty control retrovirus under pathogenic Th17 alternative (alt.) differentiation pathway in the presence of IL-1b+IL-6+IL-23; 3 biological replicates E: 2D2 Egr2-/- CD4+ T cells were differentiated under pathogenic Th17(23) conditions for 5 days. After reactivation on anti-CD3/CD28 coated plates for 48 hrs in the presence of IL-23, 2D2 Egr2-/- Th17(23) cells were transferred into TCRb-/- mice. During peak of EAE disease (day 20 after transfer), 2D2 Egr2-/- Th17 cells were purified from the spleens of Tcrb-/- mice for RNA-Seq, 3 biological replicates; F: 2D2 WT CD4+ T cells were differentiated under pathogenic Th17(23) conditions for 5 days. After reactivation on anti-CD3/CD28 coated plates for 48 hrs in the presence of IL-23, 2D2 WT Th17(23) cells were transferred into TCRb-/- mice. During peak of EAE disease (day 20 after transfer), 2D2 WT Th17(23) cells were purified from the spleens of Tcrb-/- mice for RNA-Seq, 4 biological replicates; G: 2D2 Egr2-/- CD4+ T cells were differentiated under pathogenic Th17(23) conditions prior 5 days. After reactivation on anti-CD3/CD28 coated plates for 48 hrs in the presence of IL-23, 2D2 Egr2-/- Th17(23) cells were transferred into TCRb-/- mice. During peak of EAE disease (day 20 after transfer), 2D2 Egr2-/- Th17 cells were purified from the CNS of Tcrb-/- mice for RNA-Seq, 3 biological replicates; H: 2D2 WT CD4+ T cells were differentiated under pathogenic Th17(23) conditions for 5 days. After reactivation on anti-CD3/CD28 coated plates for 48 hrs in the presence of IL-23, 2D2 WT Th17(23) cells were transferred into TCRb-/- mice. During peak of EAE disease (day 20 after transfer), 2D2 WT Th17(23) cells were purified from the CNS of Tcrb-/- mice for RNA-Seq, 4 biological replicates;