Systemic changes in serum-induced T cell transcriptional analysis and inflammatory profiles in patients who undergo islet and pancreas transplantation

Cell replacement therapy in type 1 diabetes (T1D) can be achieved by the transplantation of whole pancreas or pancreatic islets. Despite receiving conditioning regimen and immunosuppressive maintenance therapy, some patients show T cell-mediated allograft rejection and/or recurrence of autoimmunity post-transplantation. Here, we aimed to determine how the humoral environment post-transplant affects T cell activation. Inflammatory profiles were determined in sera from patients receiving either islet, pancreas, pancreas/kidney or auto-transplantation and healthy controls (HC) and T1D controls. The effect of this serum environment on T cell activation was examined by serum-induced transcriptional analysis: purified Treg and CD8⁺ memory T cells from healthy human donors were used as responder cells and exposed to low anti-CD3/CD28 bead stimulation in the presence of 30% of patient sera. Harvested RNA was subjected to RNA sequencing. Hierarchical cluster analysis of sera cytokines/chemokine profiles defined five clusters whose distribution varied substantially between serum-subject groups. T1D patients had more inflammatory profiles as compared to HC, who were largely low inflammatory, and patients post-transplant who had an IL-7 profile. There were marked differences between the serum-subject groups in the gene expression profiles of Treg and CD8⁺ T cells after activation in the presence of patient serum. An increased activation of TCR- and downstream signaling pathways was observed in the presence of sera from patients with long-standing T1D as compared to HC. Despite a high IL-7 feature in the cytokine/chemokine profile, JAK/STAT and downstream pathways of TCR-signaling were downregulated post-pancreas transplant. The findings suggest that patients with long-standing T1D have an enhanced ability to activate T cells and that serum-induced transcriptional analyses may be helpful in the management of patients post-transplant.