Immunoregulatory artificial lymph nodes restore antigen-specific tolerance in advanced multiple sclerosis.

Tolerogenic dendritic cell (tolDC) vaccines are a promising antigen-specific therapy for multiple sclerosis (MS), yet their efficacy is limited by poor homing to secondary lymphoid organs and rapid loss of the tolerogenic phenotype in native inflamed lymph nodes. Here, we developed a 3D-printed tolerogenic artificial lymph node (tol-aLN) that creates a protected immune niche for durable tolerance induction. tolDCs were loaded onto a porous gelatin methacrylate scaffold engineered for sustained C-C motif chemokine ligand 21 (CCL21) release, recruiting naïve CD4+ T cells and shielding tolDCs from an inflammatory lymph node. Geometric optimization of an orthogonal lattice scaffold enhanced spatially confined DC-T cell interactions, promoting robust and stable induction of regulatory T cells (Treg cells). In experimental autoimmune encephalomyelitis (EAE), tol-aLN implantation attenuated disease even at advanced stages by inducing antigen-specific Foxp3+ Treg cells that trafficked to the spleen, lymph nodes, and central nervous system (CNS). Conditional Treg cell depletion abolished therapeutic efficacy, indicating that Treg cells are necessary mediators of tol-aLN-induced protection. Long-term studies revealed sustained remission without impairing systemic immunity. In a myelin oligodendrocyte glycoprotein (amino acids 1 to 125) (MOG1-125)-induced EAE model, multivalent tol-aLN also efficiently suppressed inflammatory B cells and autoantibody production, reprogramming CNS B cells toward a regulatory state. Single-cell transcriptomics further revealed a global reduction in interferon-stimulated gene activity and restoration of homeostatic microglial phenotypes. Collectively, tol-aLN offers a scalable, antigen-specific platform for immune tolerance and CNS protection, with translational potential for MS and other autoimmune diseases.