Project description:In transplantation, there is a critical need for non-invasive biomarker platforms for monitoring immunologic rejection. We hypothesized that transplanted tissues release donor specific exosomes into recipient circulation/ bodily fluids, and that the quantitation and profiling of their intra-exosomal cargoes would constitute a novel biomarker platform for monitoring rejection. We tested this hypothesis in a human into mouse xenogeneic islet transplant model, and validated the concept in clinical settings of islet and renal transplantation. In the xenogeneic model, islet transplant exosomes in recipient blood were quantified over long-term follow-up using anti-human leukocyte antigen (HLA) antibody that is only expressed on human islets (p=1.6x10-14). Transplant islet exosomes were purified using anti-HLA antibody conjugated beads and their cargoes contained bona fide islet endocrine hormone markers insulin, glucagon, and somatostatin. Rejection led to significant decrease in transplant islet exosome signal (p=4x10-15), along with distinct changes in its microRNA and proteomic profiles prior to appearance of hyperglycemia. In the clinical settings of islet (n=5) and renal (n=5) transplantation, donor exosomes with respective tissue specificity for islet β cells and renal epithelial cells were reliably characterized in recipient plasma over follow-up (up to 5 years; p=0.0001). Collectively, these findings demonstrate the biomarker potential of transplant exosome characterization for providing a non-invasive window into the conditional state of the transplant tissue.
Project description:In transplantation, there is a critical need for non-invasive biomarker platforms for monitoring immunologic rejection. We hypothesized that transplanted tissues release donor specific exosomes into recipient circulation/ bodily fluids, and that the quantitation and profiling of their intra-exosomal cargoes would constitute a novel biomarker platform for monitoring rejection. We tested this hypothesis in a human into mouse xenogeneic islet transplant model, and validated the concept in clinical settings of islet and renal transplantation. In the xenogeneic model, islet transplant exosomes in recipient blood were quantified over long-term follow-up using anti-human leukocyte antigen (HLA) antibody that is only expressed on human islets (p=1.6x10-14). Transplant islet exosomes were purified using anti-HLA antibody conjugated beads and their cargoes contained bona fide islet endocrine hormone markers insulin, glucagon, and somatostatin. Rejection led to significant decrease in transplant islet exosome signal (p=4x10-15), along with distinct changes in its microRNA and proteomic profiles prior to appearance of hyperglycemia. In the clinical settings of islet (n=5) and renal (n=5) transplantation, donor exosomes with respective tissue specificity for islet β cells and renal epithelial cells were reliably characterized in recipient plasma over follow-up (up to 5 years; p=0.0001). Collectively, these findings demonstrate the biomarker potential of transplant exosome characterization for providing a non-invasive window into the conditional state of the transplant tissue.
Project description:In this study we employed transcriptome mRNA profiling of whole blood and purified CD4, CD8 T cells, B cells and monocytes in tandem with high-throughput flow cytometry in 10 kidney transplant patients sampled serially pre-transplant, 1, 2, 4, 8 and 12 weeks. We then mechanistically deconvoluted the early post-transplant immune response. The flow cytometry data confirms depletion of specific cell subsets in response to ATG induction and immunosuppression with sustained decreases in CD4 as well as CD8 cell subsets. A series of T cell activation markers were expressed from Pre-Tx to 12 weeks indicating the evolution of immunity including expansion of CD45RO+CD62L- effector memory cells. Serial whole blood transcript monitoring demonstrated over 2000 differentially expressed genes, with over 80 percent down-regulated Post-Tx. However, cell subset analysis revealed a unique spectrum of subset-specific gene expression with time-dependent changes, with contrasting significant Post-Tx gene upregulation. Our results provide a unique view of the complex evolution of immune/inflammatory molecular networks marking the early post transplant immune response. A critical finding is that analysis of the constituent blood cell subsets provides an entirely new level of detail revealing the nature of this process, effectively deconvoluting the changes that are otherwise lost in the noise of cellular complexity of whole blood. Keywords: kidney transplantation, peripheral blood, DNA microarrays, acute kidney rejection, cell subsets, flow cytometry, serial monitoring We employed Affymetrix HG-U133 Plus 2.0 GeneChips for mRNA profiling of whole blood and purified CD4, CD8 T cells, B cells and monocytes in tandem with high-throughput flow cytometry in 10 kidney transplant patients sampled serially pre-transplant, 1, 2, 4, 8 and 12 weeks. We then mechanistically deconvoluted the early post-transplant immune response.
Project description:Acute rejection in cardiac transplant patients is still a contributing factor to limited survival of the implanted heart. Currently there are no biomarkers in clinical use that can predict, at the time of transplantation, the likelihood of post-transplantation acute rejection, which would be of great importance for personalizing immunosuppressive treatment. Within the Biomarkers in Transplantation initiative, the predictive biomarker discovery focused on data and samples collected before or during transplantation such as: clinical variables, genes and proteins from the recipient, and genes from the donor. Based on this study, the best predictive biomarker panel contains genes from the recipient whole blood and from donor endomyocardial tissue and has an estimated area under the curve of 0.90. This biomarker panel provides clinically relevant prediction power and may help personalize immunosuppressive treatment and frequency of rejection monitoring.
Project description:BACKGROUND: Assessment of gene expression in peripheral blood may provide a noninvasive screening test for allograft rejection. We hypothesized that changes in peripheral blood expression profiles would correlate with biopsy-proven rejection and would resolve after treatment of rejection episodes. METHODS AND RESULTS: We performed a case-control study nested within a cohort of 189 cardiac transplant patients who had blood samples obtained during endomyocardial biopsy (EMB). Using Affymetrix HU133A microarrays, we analyzed whole-blood expression profiles from 3 groups: (1) control samples with negative EMB (n=7); (2) samples obtained during rejection (at least International Society for Heart and Lung Transplantation grade 3A; n=7); and (3) samples obtained after rejection, after treatment and normalization of the EMB (n=7). We identified 91 transcripts differentially expressed in rejection compared with control (false discovery rate <0.10). In postrejection samples, 98% of transcripts returned toward control levels, displaying an intermediate expression profile for patients with treated rejection (P<0.0001). Cluster analysis of the 40 transcripts with >25% change in expression levels during rejection demonstrated good discrimination between control and rejection samples and verified the intermediate expression profile of postrejection samples. Quantitative real-time polymerase chain reaction confirmed significant differential expression for the predictive markers CFLAR and SOD2 (UniGene ID No. 355724 and No. 384944). CONCLUSIONS: These data demonstrate that peripheral blood expression profiles correlate with biopsy-proven allograft rejection. Intermediate expression profiles of treated rejection suggest persistent immune activation despite normalization of the EMB. If validated in larger studies, expression profiling may prove to be a more sensitive screening test for allograft rejection than EMB. Experiment Overall Design: Case- control study with three groups. Patients with rejection (r1-r7), follow-up samples after treatment of rejection (post1-7), and controls with no rejection (con1-7)
Project description:Kidney transplant recipients are at particular risk for developing tumors, many of which are now routinely treated with immune checkpoint inhibitors (ICIs); however, ICI therapy can precipitate transplant rejection. We utilized TCR sequencing to identify and track alloreactive T cells in a patient with melanoma who experienced kidney transplant rejection following ICI therapy. ICI therapy was associated with a sharp increase in circulating alloreactive CD8+ T cell clones, many of which were also detected in the rejected kidney but not at tumor sites. Longitudinal and cross-tissue TCR analyses revealed unintended expansion of alloreactive CD8+ T cells induced by ICI therapy for cancer, coinciding with ICI-associated organ rejection.
Project description:Kidney transplant recipients are at particular risk for developing tumors, many of which are now routinely treated with immune checkpoint inhibitors (ICIs); however, ICI therapy can precipitate transplant rejection. We utilized TCR sequencing to identify and track alloreactive T cells in a patient with melanoma who experienced kidney transplant rejection following ICI therapy. ICI therapy was associated with a sharp increase in circulating alloreactive CD8+ T cell clones, many of which were also detected in the rejected kidney but not at tumor sites. Longitudinal and cross-tissue TCR analyses revealed unintended expansion of alloreactive CD8+ T cells induced by ICI therapy for cancer, coinciding with ICI-associated organ rejection.
Project description:Kidney transplant recipients are at particular risk for developing tumors, many of which are now routinely treated with immune checkpoint inhibitors (ICIs); however, ICI therapy can precipitate transplant rejection. We utilized TCR sequencing to identify and track alloreactive T cells in a patient with melanoma who experienced kidney transplant rejection following ICI therapy. ICI therapy was associated with a sharp increase in circulating alloreactive CD8+ T cell clones, many of which were also detected in the rejected kidney but not at tumor sites. Longitudinal and cross-tissue TCR analyses revealed unintended expansion of alloreactive CD8+ T cells induced by ICI therapy for cancer, coinciding with ICI-associated organ rejection.