T cell repertoire analysis suggests a prominent bystander response in human cardiac allograft vasculopathy

Abstract

T cells are implicated in the pathogenesis of cardiac allograft vasculopathy (CAV), yet their clonality, specificity, and function are incompletely defined. Here we used T cell receptor β chain (TCRB) sequencing to study the T cell repertoire in the coronary artery, endomyocardium, and peripheral blood at the time of retransplant in four cases of CAV and compared it to the immunoglobulin heavy chain variable region (IGHV) repertoire from the same samples. High‐dimensional flow cytometry coupled with single‐cell PCR was also used to define the T cell phenotype. Extensive overlap was observed between intragraft and blood TCRBs in all cases, a finding supported by robust quantitative diversity metrics. In contrast, blood and graft IGHV repertoires from the same samples showed minimal overlap. Coronary infiltrates included CD4+ and CD8+ memory T cells expressing inflammatory (IFNγ, TNFα) and profibrotic (TGFβ) cytokines. These were distinguishable from the peripheral blood based on memory, activation, and tissue residency markers (CD45RO, CTLA‐4, and CD69). Importantly, high‐frequency rearrangements were traced back to endomyocardial biopsies (2–6 years prior). Comparison with four HLA‐mismatched blood donors revealed a repertoire of shared TCRBs, including a subset of recently described cross‐reactive sequences. These findings provide supportive evidence for an active local intragraft bystander T cell response in late‐stage CAV.

Current Desensitization Strategies in Heart Transplantation

“…In myeloma patients, this was accompanied by augmented CD8+ T effector memory responses with enhanced IFNγ secretion in response to viral antigens ( 158 ). Given the potential role of heterologous immunity and/or bystander T-cells in rejection, this latter finding is also noteworthy ( 28 , 159 ). Interestingly, both of the aforementioned cases showed signs of TCMR on follow up biopsies consistent with the findings in a non-human primate model ( 155 – 157 ).…”

Integrated analysis toolset for defining and tracking alloreactive T-cell clones after human solid organ and hematopoietic stem cell transplantation

“…At minimum, columns are required for CD4 baseline unstimulated repertoire, CD4 antigen-stimulated repertoire, CD8 baseline unstimulated repertoire, CD8 antigen-stimulated repertoire, and at least one post-transplant blood or biopsy specimen (use biopsy as a demonstrative example in following text, figure and table). The data matrix format is provided as standard output from Adaptive Biotechnologies' ImmunoSeq platform, which is utilized by our lab and many other groups for TCR-Sequencing [1][2][3][4][5][6][7][8], and we therefore take this as input for downstream analysis.…”

“…Our method and R script [11] have been extensively used by us [1][2][3][4][5][6] and others [7,8] in multiple types of human SOT studies, including intestine [2,5,6], liver [4], heart [7], kidney [8] and combined kidney and bone marrow transplants [1]. Our platform allows the integration of T cell clonotype, alloreactivity and RNA profiling on the single cell level to relate T cell functional profiles with clonotypes of individual T cells [6].…”

“…Furthermore, our method could help to develop alternative monitoring strategies to minimize or entirely avoid invasive and delayed diagnostic procedures after human kidney transplantation [8]. A list of scholarly publications enabled by this software is presented in the references [1][2][3][4][5][6][7][8], along with ongoing research projects [12][13][14].…”

Advanced Genomics-Based Approaches for Defining Allograft Rejection With Single Cell Resolution

“…Utilization of scRNAseq not only enables the transcriptomic description of these cells responsible for rejection, but also provides the opportunity to study the allospecificity and track T and B cell clonal dynamics. Studies of cardiac cellular rejection have shown that graft infiltrating T cells overlapped with those found in the peripheral blood, but interestingly, there was minimal overlap of the B cells between the two compartments ( 112 ). The authors used this data to suggest that there is B cell clonal expansion in the allograft, which could occur as part of a well-known phenomenon of germinal center-like structures present in chronically rejecting allografts ( 113 , 114 ).…”