Th111 - Tissue-Engineered Lymph Node Fibroblastic Reticula for Localized Immunomodulation of Diabetogenic T Cells

Leonor Teles – University of Miami; Zachary Wilkes – University of Miami; Logan Beatty – University of Miami; Ana Hernandez – University of Miami; Camillo Bechi Genzano – Columbia University; Alice Tomei – University of Miami

Abstract Text: Current treatments for autoimmune diseases like type 1 diabetes (T1D) are limited to systemic T cell-targeting approaches, carrying significant risks. Therapies that are more localized and antigen (Ag)-specific are more desirable. Fibroblastic reticular cells (FRCs) are lymph node stromal cells that build 3D reticula and act as non-professional antigen-presenting cells with immunomodulatory effects. Upon inflammation, FRCs expand the lymph node and upregulate Ag-presenting machinery (MHC-I/II) and immune checkpoint molecules (PD-L1) while maintaining low co-stimulation (CD80/86). FRCs expressing model Ags induced Ag-specific naïve T-cell deletion in vivo indicating their potential for targeting Ag-specific T cells. However, their therapeutic role in Ag-specific immunomodulation against T1D has not been tested. We designed a 3D biomaterial platform for localized FRC-mediated immunomodulation of T1D. We found that biocompatible macroporous gelatin scaffolds promote murine and human FRC attachment and reticula formation during 21-day in vitro culture and after subcutaneous transplantation in mice (using bioluminescence imaging of luciferase-expressing FRCs). After 3-day in vitro co-culture with FRC reticula pulsed with selected T1D peptide Ags, we found specific CD4+ and CD8+ T-cell engagement via proliferation (CellTrace dilution) and CD44/CD25 upregulation. Compared to anti-CD3/CD28 stimulation, cytotoxic phenotype (Granzyme B) of engaged specific CD8+ T-cell was reduced while anergic (CD73/FR4) and regulatory (CD25/FoxP3) phenotype of Ag-specific CD4+ but not polyclonal CD4+ T-cell was increased. Using CD4+ T cells from BDC2.5 FoxP3-RFP mice, we found that Ag-presenting FRCs promoted both induction and expansion of Ag-specific T cells. Thus, our FRC platform could provide novel means for local, retrievable, Ag-specific immunomodulation for T1D.