Anti-TIM-4 Monoclonal Antibody Treatment Reduces Autoreactive CD8+ T Cells and Restores Euglycemia in New-Onset Diabetic NOD Mice

Abstract

Type 1 diabetes (T1D) is driven by immune-mediated destruction and dysfunction of pancreatic β-cells, with autoreactive CD8+ T cells serving as important effectors of β-cell injury. T-cell immunoglobulin and mucin domain-containing protein 4 (TIM-4) is expressed predominantly by macrophages and subsets of antigen-presenting cells and participates in phosphatidylserine recognition, efferocytosis, and regulation of adaptive immune responses. We investigated whether short-course TIM-4 targeting alters diabetogenic antigen-specific CD8+ T-cell responses in female non-obese diabetic (NOD) mice with new-onset diabetes. Mice received an anti-TIM-4 monoclonal antibody (3 mg/kg, intraperitoneally, every 2 days for 4 doses). Autoreactive CD8+ T cells were quantified using H-2Kd tetramers loaded with an insulin peptide or the islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)206–214 peptide, and pancreatic histology and intracellular interferon-γ (IFN-γ), interleukin-17 (IL-17), and forkhead box P3 (FoxP3) staining were assessed. Euglycemia was restored in 8 of 11 treated mice (72.7%) despite cessation of therapy. Anti-TIM-4 monoclonal antibody treatment markedly reduced IGRP206–214-reactive CD8+ T-cell frequencies in pancreatic lymph nodes and pancreas compared with untreated diabetic mice and was associated with preservation of pancreatic islet architecture. Treatment was also associated with lower IFN-γ and IL-17 expression and a higher frequency of FoxP3+ CD4+ T cells in pancreatic lymph nodes. These findings identify TIM-4-associated immune pathways as potential modulators of diabetogenic antigen-specific CD8+ T-cell responses and support further mechanistic evaluation of TIM-4 targeting in autoimmune diabetes.