Tu143 - In vivo Reprograming of Stromal Cells for Tolerogenic Immunotherapy Using Mrnas with Restricted Expression

Remi Creusot, PhD – Associate Professor, Medicine, Columbia Center for Translational Immunology and Department of Medicine, Columbia University Medical Center

Abstract Text: The type of antigen-presenting cells (APCs) targeted by immunotherapy greatly influences its efficacy. Presentation of autoantigens by hematopoietic APCs may negatively affect their ability to induce tolerance and ameliorate autoimmune disease if they become immunogenic. Moreover, these APCs are reported to have impairments in inducing tolerance in Type 1 diabetes (T1D). In contrast, stromal cells (SCs) could favor tolerance as they lack costimulatory molecules and express various types of inhibitory molecules. However, SCs are not effective APCs due to low MHC expression levels. Overexpression of constitutively active STAT1 (STAT1c) in SCs, like exposure to IFN-γ, resulted in MHC and PD-L1 upregulation, but not CD80 and CD86. We transfected various cell types with GFP mRNA formulated into nanoparticles and confirmed that incorporation of miR-142 target (T) sequences into the mRNA restricts expression to SCs in vitro and in vivo. Delivery of autoantigen-encoding mRNA with miR-142T led to a limited CD4 T cell response in non-obese diabetic (NOD) mice, but codelivery with STAT1c-encoding mRNA returned the response to the level seen with autoantigen mRNA without miR-142T. Interestingly, SCs express higher MHC-II levels in pancreatic lymph nodes due to its more inflamed environment, and there, they elicited robust CD4 T cell responses without the need for STAT1c. Our findings show proof-of-concept that SCs can be selectively targeted and reprogramed in vivo to serve as effective APCs for immunotherapy of T1D. Further studies will aim to confirm the tolerogenic nature of T cell responses and the resulting effect on disease progression in NOD mice.