ABSTRACT: Transcriptomic signature of the CD24hiCD38hi transitional B cells associated with an immunoregulatory phenotype in renal transplant recipient.
Project description:The role of B cells after transplant regarding allograft rejection or tolerance has become a topic of major interest. Recently, in renal transplant recipients, a B cell signature characterized by the overexpression of CD19+CD38hiCD24hi transitional B cells has been observed in operationally tolerant patients and in Belatacept treated patients with significant lower incidence of donor specific antibodies. The phenotypic and functional characterization of these transitional B cells is far to be exhaustive. We present the first transcriptomic and phenotypic analysis associated with this phenotype. Three populations were studied and compared: (i) transitional CD24hiCD38hi (ii) CD24+CD38- and (iii) CD24intCD38int populations. Peripheral blood mononuclear cells were isolated from 5 healthy donors and CD20+ B cells were isolated by magnetic beads. Three B cells populations were then sorted by flow cytometry: CD19+CD24hiCD38hi (test), CD19+CD24+CD38- (control 1) and CD19+CD24intCD38int (control 2)
Project description:The role of B cells after transplant regarding allograft rejection or tolerance has become a topic of major interest. Recently, in renal transplant recipients, a B cell signature characterized by the overexpression of CD19+CD38hiCD24hi transitional B cells has been observed in operationally tolerant patients and in Belatacept treated patients with significant lower incidence of donor specific antibodies. The phenotypic and functional characterization of these transitional B cells is far to be exhaustive. We present the first transcriptomic and phenotypic analysis associated with this phenotype. Three populations were studied and compared: (i) transitional CD24hiCD38hi (ii) CD24+CD38- and (iii) CD24intCD38int populations.
Project description:Despite significant improvements in solid organ transplant outcomes over the past several decades, our limited understanding of the immune interface between donor organs and recipient immune systems has hindered the development of strategies to expand immunoregulatory cell populations and induce immune tolerance in transplant recipients. Given that group 2 innate lymphoid cells (ILC2s) are resident in transplanted solid organs, play a role in wound healing, and coordinate immunoregulatory cell populations, we sought to investigate their function in the alloimmune response. Using a murine heterotopic cardiac transplant model, we demonstrate that recipient ILC2s replace donor ILC2s and upregulate MHC class II (MHCII) without expressing costimulatory molecules. These recipient-derived ILC2s process and present alloantigens, inducing CD4+ T cell anergy through the Caspase-3-dependent pathway. In the absence of recipient-derived ILC2s, we observed a marked increase in infiltrating donor-reactive CD4+ T cells and significantly reduced allograft survival. Furthermore, in vivo expansion of ILC2s via IL-33 administration prolonged murine heart allograft survival. Collectively, these findings reveal a critical and previously unrecognized immunoregulatory role of host-derived ILC2s in solid organ transplantation, where they promote alloimmune tolerance by inducing anergy in alloreactive CD4+ T cells.
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:Mycophenolic acid is an immunosuppressant commonly used to prevent renal transplant rejection and treat glomerulonephritis. Despite its widespread use, there is a clinical need to reduce solid-organ transplant rejection and improve rates of complete therapeutic response in autoimmunity. Single-cell RNA-sequencing (n=6) in lymphocytes was performed at baseline, post-stimulation, and post-mycophenolate treatment. This study identifies a polygenic transcriptomic signature in lymphocyte sub-populations predictive of mycophenolate response.
Project description:Tissue resident memory T cells (TRM) maintain immunity in diverse sites as determined in mouse models, while their establishment and role in human tissues has been difficult to assess. Here, we investigated human lung TRM generation, maintenance and function in airway samples obtained longitudinally from HLA-disparate lung transplant recipients, where donor and recipient T cells could be localized and tracked over time. Donor T cells persist specifically in the lungs (and not blood) of transplant recipients and express high levels of TRM signature markers including CD69, CD103, and CD49a, while lung-infiltrating recipient T cells gradually acquire TRM phenotypes over months in vivo. Single cell transcriptome profiling of airway T cells reveals that donor T cells comprise two TRM-like subsets with varying levels of expression of TRM-associated genes while recipient T cells comprised non-TRM and similar TRM-like subpopulations, suggesting de novo TRM generation. Transplant recipients exhibiting higher frequencies of persisting donor TRM experienced fewer adverse clinical events such as primary graft dysfunction and acute cellular rejection compared to recipients with low donor TRM persistence, suggesting that monitoring TRM dynamics could be clinically informative. Together, our results provide novel spatial and temporal insights into how human TRM develop, function, persist, and impact tissue integrity within the complexities of lung transplantation.
Project description:To investigate the role of recipient neutrophil intracellular HMGB1 in early allograft injury after liver transplant. Using a mouse orthotopic liver transplant model, as well as LPS injection, we found that neutrophils significantly infiltrate the liver after liver transplant and LPS challenge. Deficiency of neutrophil HMGB1 enhances their activation, boosts their pro-oxidant and pro-inflammatory phenotype, and hinders biosynthesis and metabolism of inositol polyphosphates. Overall, these events exacerbate early allograft injury after liver transplant.