Th132 - A Tolerogenic Lipid Nanoparticle Delivery System for Antigen-specific Immune Tolerance

Lindsay Pallo – University of British Columbia; Sam Chen – Integrated Nanotherapeutics; Victoria Ng – Integrated Nanotherapeutics; Josh Zaifman – Integrated Nanotherapeutics; Anne Nguyen – Integrated Nanotherapeutics; Pranjali Singh – Integrated Nanotherapeutics; Sarah Zhang – Integrated Nanotherapeutics; C Verchere – University of British Columbia; Yuen Yi Tam – Integrated Nanotherapeutics

Abstract Text: The immunogenicity of mRNA lipid nanoparticles (LNPs) is advantageous for vaccines but detrimental for antigen-specific immune tolerance (ASIT). To unlock the potential of mRNA-mediated antigen delivery in tolerance, we developed a tolerogenic LNP (tLNP) system to co-deliver mRNA and immunomodulators to antigen-presenting cells in vivo. Relative to mRNA-only LNPs, tLNPs exhibit comparable biodistribution and mRNA delivery while reducing the associated inflammatory response in mice. In a prime-boost mouse model of ovalbumin immunization, tLNPs reduced antigen-specific IFNγ and IgG1 production (P < 0.0001 vs mRNA-only LNPs). We identified a lead tLNP composition that inhibited antigen-specific CD4 proliferation and Th1/Th2 cytokine secretion, increased antigen-specific Tregs ex vivo, and reduced autoimmune infiltration of pancreatic islets in pre-diabetic NOD mice after 2 injections (P=0.02 vs controls). Subsequently, we tested whether tLNPs could induce ASIT and prevent diabetes in NOD mice. Female NOD mice injected biweekly from 5-15 weeks with our lead tLNP (islet autoantigen mRNA and immunomodulator) had dramatically reduced diabetes incidence relative to buffer-injected controls (13.3% vs 66.7% diabetes free at 30 weeks, P=0.0002) and delayed diabetes onset. LNPs carrying mRNA only or irrelevant antigen with immunomodulator were ineffective (66.7% and 53.3% diabetes free at 30 weeks), revealing both autoantigen and immunomodulatory components are essential for ASIT. Furthermore, tLNPs inhibited mouse and human dendritic cell maturation ex vivo and increased the frequency of splenic Tregs in NOD mice (P=0.006) in an antigen-specific manner. In conclusion, this novel tLNP system induces ASIT in NOD mice and could enable mRNA therapeutics for tolerance across multiple indications.