The TCF-1-E-protein axis preserves stem-like Th17 identity and prevents autoimmune pathology.

The TCF-1-E-protein axis maintains stem-like Th17 identity and prevents autoimmune pathology, with TCF-1 deficiency leading to increased pathogenic features in Th17 cells.

• Why it matters: Understanding how Th17 cells transition from homeostatic to pathogenic states is crucial for autoimmune disease intervention, as the mechanisms sustaining TCF-1 expression and preventing pathogenic conversion are largely unknown.
• What they did: Using an IL-17 fate-mapping system with Tcf7 deletion, the study examined how TCF-1 influences Th17 cell states, revealing that TCF-1 maintains homeostatic identity and prevents pathogenic features, with single-cell transcriptomics showing early downregulation of TCF-1 during pathogenic conversion.
• The result: Disruption of the TCF-1-E-protein feedback loop destabilizes Th17 cells, leading to loss of stem-like markers, acquisition of pathogenic features, and exacerbation of experimental autoimmune encephalomyelitis, highlighting the axis's role in autoimmune regulation.