ENPP1 governs the metabolic regulation of effector T cells in autoimmunity by detecting cytosolic mitochondrial DNA.

T cells play a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE), yet the underlying molecular mechanisms governing their fate remain elusive. Here, we identify cytosolic mitochondrial DNA (mtDNA) as an intrinsic trigger for driving effector T cell differentiation in patients with SLE. Specifically, accumulated cytosolic mtDNA is sensed by ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which enhances the transcription of GLUT1 and glycolysis in SLE T cells. This metabolic shift reduces lipogenesis and depletes free fatty acids (FFAs), impairing the N-myristylation and lysosomal localization of AMP-activated protein kinase (AMPK). Inactive AMPK fails to restrain mammalian target of rapamycin complex 1 (mTORC1), leading to its hyperactivation and driving the mal-differentiation of effector T cells. Consequently, interventions targeting ENPP1, glycolysis, AMPK, and mTORC1 effectively inhibit the generation of immunoglobulin (Ig)G anti-double-stranded DNA (dsDNA) and the progression of lupus nephritis in humanized SLE chimeras. Overall, our findings uncover an mtDNA-ENPP1-metabolic axis that governs effector T cell fate in autoimmunity.