CCTI - Columbia University New York, New York, United States
Abstract Text: Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease. The role of abnormal thymic selection of autoreactive T cells in driving human T1D is unknown, as thymocytes are not accessible for study in patients. We have developed a “Personalized Immune (PI)” human immune system mouse model that allows comparison of thymocyte selection in T1D patients and healthy controls (HCs). PI mice are constructed by administering bone marrow CD34+ hematopoietic stem cells (HSCs) from HC or T1D donors to thymectomized NSG mice that also receive human fetal thymic tissue sharing the same T1D class II HLA risk allele with both adult human donor. Following immune reconstitution (18 to 24 weeks post-transplant), animals are sacrificed and thymocyte suspensions undergo single-cell 5’RNA sequencing (10X Genomics). A total of 3 T1D and 5 HC thymocyte suspensions from 2 T1D and 2 HC donors have been sequenced and analysis is in progress. Transcriptional profiles have revealed maturing thymocyte subsets previously identified in normal human thymus (Chopp et. al 2020). Preliminary analysis reveals statistically significant differential expression of genes driving thymocyte maturation at the immature single positive, unselected (CD69-) and positively selected (CD69+) double positive stages between T1D and HC thymocytes, suggesting HSC-intrinsic differences in TCR signaling. Correlations with T1D-associated single nucleotide polymorphisms in T cell signaling such as SH2B3 and Erk/MAP kinase pathway genes, which were enriched in some T1D donors and associated with defects in negative selection of a transgenic islet autoreactive TCR, will be informative.
