Interferon subverts an AHR-JUN axis to promote CXCL13+ T cells in lupus

SLE is prototypical autoimmune disease driven by pathologic T cell-B cell interactions. Expansion of B cell-helper T cells including T follicular helper (Tfh) and T peripheral helper (Tph) cells is a prominent feature of systemic lupus erythematosus (SLE). Human Tfh and Tph cells characteristically produce high levels of the B cell chemoattractant CXCL13, yet regulation of T cell CXCL13 production and the relationship between CXCL13+ T cells and other T cell states remains unclear. Here, we identify an imbalance in CD4 T cell phenotypes in SLE patients, with expansion of PD-1+/ICOS+ CXCL13+ T cells and reduction of CD96hi IL-22+ T cells. Using CRISPR screens, we identify the aryl hydrocarbon receptor (AHR) as a potent negative regulator of CXCL13 production by human CD4 T cells. Transcriptomic, epigenetic, and functional studies demonstrate that AHR coordinates with AP-1 family member JUN to prevent CXCL13+ Tph/Tfh cell differentiation and promote an IL-22+ phenotype. Type I interferon (IFN), a pathogenic driver of SLE, opposes AHR and JUN to promote T cell production of CXCL13. These results place CXCL13+ Tph/Tfh cells on a polarization axis opposite from Th22 cells and reveal AHR, JUN, and IFN as key regulators of these divergent T cell states. Refer to individual Series