GLUT1-mediated glucose flux constrains autoreactive but not foreign antigen-specific B-cell responses.

Emerging evidence from lupus-prone mice and patients with systemic lupus erythematosus implicates enhanced glycolysis in lymphocytes as a driver of disease. We previously showed that the pharmacologic blockade of glycolysis reduced the production of autoantibodies without affecting antibodies induced by immunization to a foreign protein. Here we used CRISPR/Cas9 to reduce the expression of glucose transporter GLUT1 in B cells from autoreactive AM14 Vk8R (AM14) and antigen-specific B1-8 Jκ (B1-8) transgenic mice, comparing intrinsic glycolytic requirements across disease-relevant contexts. Following adoptive transfer into BALB/c recipients, Glut1 knockdown (Glut1KD) decreased the persistence of AM14 B cells, their differentiation into plasmablasts, and production of antibodies upon immunization with the PL2-3 hybridoma that activates both their B-cell receptor and endosomal TLR. In addition, PL2-3-stimulated Glut1KD AM14 B cells selectively reduced their CD80 expression both in vivo and in vitro, as well as ATP production and mammalian target of rapamycin (mTOR) signaling in vitro. In contrast, Glut1KD B1-8 B cells retained persistence, plasmablast output, and nitrophenyl (NP)-specific IgM production after NP-OVA immunization, with a selective reduction in the proliferation of naive B cells. Bioenergetic output was preserved despite Glut1KD in both clones stimulated with TLR7 agonist R848, but CD80 and mTOR signaling were differentially affected. Thus, GLUT1-dependent glycolysis is essential for immune complex-driven autoreactive B-cell activation yet largely dispensable for antigen-specific responses, identifying metabolic checkpoints that may selectively restrain pathogenic B cells while sparing protective humoral immunity.