Type 1 diabetes (T1D) is a multifactorial autoimmune disease that requires genetic susceptibility as well as environmental triggers to induce disease onset. Genetic association studies have implicated the IFIH1 gene, encoding for melanoma differentiation-associated protein 5 (MDA5), a cytosolic sensor of dsRNA, to be involved in T1D susceptibility and resistance. Stimulation of the MDA5 signaling pathway activates the transcription factors IRF3 and NF-κB p65, which induce Type I IFNs synthesis, which through autocrine signaling initiate an antiviral transcriptional program. Single nucleotide polymorphisms (SNPs) in the IFIH1 gene such as rs1990760 and rs3747517, which results in a non-synonymous mutation that changes alanine at position 946 to a threonine and histidine at position 843 to arginine, respectively, is highly associated with increased risk for T1D. Studies in human PBMCs and mice have demonstrated that the A946T SNP results in an increased sensitivity to viral ligands and subsequently a stronger downstream IFN response. Our central hypothesis is that T1D-associated SNPs result in an exacerbated islet-resident macrophage and dendritic cell immune response that result in an increase in Type I IFNs which contributes to the initiation of autoimmunity. This will be tested by using spatial transcriptomics and proteomics of paraffin- and OCT- embedded section and pancreas slices from healthy donors, patients with autoantibody positivity, and patients with T1D that are genotyped for IFIH1 SNPs that contribute to T1D susceptibility.
