Characterizing Donor‐Specific T Cells in Islet Transplant Recipients Using scRNA‐seq

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Organ transplants remain an effective treatment of various end‐stage diseases. Induction of tolerance has remained the elusive goal of transplant community to overcome the mortality and morbidity associated with chronic immunosuppression for long term function of the transplanted organs. We have developed a tolerogenic protocol using apoptotic donor leukocytes (ADLs) that circumvents the need for immunosuppressants and have established the efficacy of ADLs for islet transplants in macaques with diabetes. However, the mechanism by which ADLs induce tolerance has not been fully elucidated. Single‐cell RNA‐sequencing (scRNA‐seq) has proven to be a powerful tool for precisely tracking changes to specific cell types and cell developmental trajectories. Flow sorting using fluorochrome‐labelled MHC class II tetramers was used to isolate donor‐specific T cells from macaques that did and did not receive ADLs prior to an islet transplant, and scRNA‐seq on the 10X Genomics platform was used to characterize these cells. Transcription profiling, TCR fingerprinting and functional clustering of the scRNA‐seq data was used to describe how treatment with ADLs altered specific T cell subtypes, as well as how they develop and interconvert between subtypes. Additionally, combining scRNA‐seq data with the macaques’ clinical outcomes will enable identification of biomarkers that can alert physicians to the fate of the transplanted islets (tolerance or rejection). The results of this project enable a better understanding of the fundamental molecular mechanisms of tolerance induced by ADLs, and further validation studies of the identified biomarkers could greatly aid the physicians’ ability to non‐invasively monitor transplant recipients.Support or Funding InformationFunding from Diabetes Research Wellness Foundation