Insights from immunoproteomic profiling of a rejected full-face transplant.

Vascularized composite allografts (VCAs) of faces and extremities are subject to chronic rejection that is incompletely understood. Here we report on immunoproteomic evaluation of a full facial VCA removed 88 months after transplantation due to chronic rejection. CD8-positive T cells of donor (graft) origin infiltrate deep intragraft arteries in apposition to degenerating endothelium of chimeric recipient origin in association with arteriosclerotic alterations. Digital spatial proteomic profiling highlighted proteins expressed by activated cytotoxic T cells and macrophages as well as pathway components involved in atherogenic responses, including Indoleamine 2,3-Dioxygenase 1 (IDO1) and Stimulator of Interferon Response CGAMP Interactor (STING). Chronic facial VCA rejection thus involves T cell/macrophage-mediated accelerated arteriosclerosis not normally represented in punch biopsies and potentially driven by persistent graft-resident effector T cells and recipient target endothelium that chimerically repopulates graft arteries.

Single-cell profiling reveals unique features of diabetogenic T cells in anti-PD-1-induced type 1 diabetes mice.

Immune-related adverse events (irAEs) are a notable complication of PD-1 cancer immunotherapy. A better understanding of how these iatrogenic diseases compare with naturally arising autoimmune diseases is needed for treatment and monitoring of irAEs. We identified differences in anti-PD-1-induced type 1 diabetes (T1D) and spontaneous T1D in non-obese diabetic (NOD) mice by performing single-cell RNA-seq and TCR-seq on T cells from the pancreas, pancreas-draining lymph node (pLN), and blood of mice with PD-1-induced T1D or spontaneous T1D. In the pancreas, anti-PD-1 resulted in expansion of terminally exhausted/effector-like CD8+ T cells, an increase in T-bethi CD4+FoxP3- T cells, and a decrease in memory CD4+FoxP3- and CD8+ T cells in contrast to spontaneous T1D. Notably, anti-PD-1 caused increased TCR sharing between the pancreas and the periphery. Moreover, T cells in the blood of anti-PD-1-treated mice expressed markers that differed from spontaneous T1D, suggesting that the blood may provide a window to monitor irAEs rather than relying exclusively on the autoimmune target organ.