Project description:Kidney transplant recipients are currently treated with nonspecific immunosuppressants that cause severe systemic side effects. Current immunosuppressants were developed based on their effect on T-cell activation rather than the underlying mechanisms driving alloimmune responses. Thus, understanding the role of the intragraft microenvironment will help us identify more directed therapies with lower side effects. To understand the role of the alloimmune response and the intragraft microenvironment in cellular rejection progression, we conducted a Single nucleus RNA sequencing (snRNA-seq) on one human non-rejecting kidney allograft sample, one borderline sample, and T-cell mediated rejection (TCMR) sample (Banff IIa). We studied the differential gene expression and enriched pathways in different conditions, in addition to ligand-receptor (LR) interactions.Pathway analysis of T-cells in borderline sample showed enrichment for allograft rejection pathway, suggesting that the borderline sample reflects an early rejection. Hence, this allows for studying the early stages of cellular rejection. Moreover, we showed that focal adhesion (FA), IFNg pathways, and endomucin (EMCN) were significantly upregulated in endothelial cell clusters (ECs) of borderline compared to ECs TCMR. Furthermore, we found that pericytes in TCMR seem to favor endothelial permeability compared to borderline. Similarly, T-cells interaction with ECs in borderline differs from TCMR by involving DAMPS-TLRs interactions. Our data revealed novel roles of T-cells, ECs, and pericytes in cellular rejection progression, providing new clues on the pathophysiology of allograft rejection.
Project description:Acute rejection of human allografts has been viewed mostly through the lens of adaptive immunity, and the intragraft landscape of innate immunity genes has not been characterized in an unbiased fashion. We did RNA sequencing of 34 kidney allograft biopsy specimens from 34 adult recipients; 16 were categorized as Banff acute T-cell mediated rejection (TCMR) and 18 as normal. Computational analysis of intragraft mRNA transcriptome identified significantly higher abundance of mRNA for pattern recognition receptors in TCMR compared to normal biopsies, as well as increased expression of mRNAs for cytokines, chemokines, interferons, and caspases. Intragraft levels of calcineurin mRNA were higher in TCMR biopsies suggesting under immunosuppression compared to normal biopsies. Cell-type enrichment analysis revealed higher abundance of dendritic cells and macrophages in TCMR biopsies. Damage associated molecular patterns, the endogenous ligands for pattern recognition receptors, as well markers of DNA damage were higher in TCMR. mRNA expression patterns supported increased calcium flux and indices of endoplasmic, cellular oxidative, and mitochondrial stress were higher in TCMR. Expression of mRNAs in major metabolic pathways were decreased in TCMR. Our global and unbiased transcriptome profiling identified heightened expression of innate immune system genes during an episode of TCMR in human kidney allografts.
Project description:Graft acceptance without the need for immunosuppressive drugs is the ultimate goal of transplantation therapy. In murine liver transplantation, allografts are accepted across major histocompatibility antigen complex barriers without the use of immunosuppressive drugs and constitute a suitable model for research on immunological rejection and tolerance. MicroRNA (miRNA) has been known to be involved in the immunological responses. In order to identify mRNAs in spontaneous liver allograft tolerance, miRNA expression in hepatic allografts was examined using this transplantation model. According to the graft pathological score and function, miR-146a, 15b, 223, 23a, 27a, 34a and 451 were upregulated compared with the expression observed in the syngeneic grafts. In contrast, miR-101a, 101b and 148a were downregulated. Our results demonstrated the alteration of miRNAs in the allografts and may indicate the role of miRNAs in the induction of tolerance after transplantation. Furthermore, our data suggest that monitoring the graft expression of novel miRNAs may allow clinicians to differentiate between rejection and tolerance. A better understanding of the tolerance inducing mechanism observed in murine hepatic allografts may provide a therapeutic strategy for attenuating allograft rejection.
Project description:Graft acceptance without the need for immunosuppressive drugs is the ultimate goal of transplantation therapy. In murine liver transplantation, allografts are accepted across major histocompatibility antigen complex barriers without the use of immunosuppressive drugs and constitute a suitable model for research on immunological rejection and tolerance. MicroRNA (miRNA) has been known to be involved in the immunological responses. In order to identify mRNAs in spontaneous liver allograft tolerance, miRNA expression in hepatic allografts was examined using this transplantation model. According to the graft pathological score and function, miR-146a, 15b, 223, 23a, 27a, 34a and 451 were upregulated compared with the expression observed in the syngeneic grafts. In contrast, miR-101a, 101b and 148a were downregulated. Our results demonstrated the alteration of miRNAs in the allografts and may indicate the role of miRNAs in the induction of tolerance after transplantation. Furthermore, our data suggest that monitoring the graft expression of novel miRNAs may allow clinicians to differentiate between rejection and tolerance. A better understanding of the tolerance inducing mechanism observed in murine hepatic allografts may provide a therapeutic strategy for attenuating allograft rejection. B10.BR mice were used as donors and B10.D2 mice were used as recipients. Liver allo-transplantation surgery on the mice was performed in this combination. Three mice from each group were sacrificed, and the liver grafts were removed on days 5, 8, 14 and 100 after transplantation. Total RNA, including miRNA was isolated. 100ng of total RNA was labeled by Cy3 and used as probe for hybridization to the microarray.
Project description:Circulating anti-HLA donor-specific antibodies (HLA-DSA) are often absent in serum of kidney allograft recipients with biopsies demonstrating histology of antibody-mediated rejection (ABMRh). In this multicenter study, we aimed to elucidate whether the transcriptional profile of biopsies with HLA-DSA negative ABMRh can indicate an undetected humoral etiology, or whether HLA-DSA negative ABMRh should be considered as a distinct histomolecular entity.
Project description:Follicular helper T (Tfh) cells have been implicated in controlling rejection after allogeneic kidney transplantation, but the precise subsets, origins and functions of Tfh cells in this process have not been fully characterized. Here we show that a subset of effector Tfh cell marked by previous IL- 21 production is potently induced during allogeneic kidney transplantation and is inhibited by immunosuppressive agents. Single-cell RNAseq revealed that these lymph node effector Tfh cells have transcriptional and clonal overlap with IL-21 producing kidney infiltrating Tfh cells, implicating common origins and developmental trajectories. To investigate the precise functions of IL-21 producing effector Tfh cells in lymph nodes and allografts, we used a mouse model to selectively eliminate these cells and assessed allogeneic B cell clonal dynamics using a single B cell culture system. We found that IL-21 producing effector Tfh cells were essential for transplant rejection by regulating donor-specific germinal center B cell clonal dynamics both systemically in the draining lymph node and locally within kidney grafts. Thus, IL-21 producing effector Tfh cells have multifaceted roles in antibody-mediated rejection after kidney transplantation by promoting B cell alloimmunity.
Project description:The aim of this study was to investigate correlations between early subclinical findings (10 and 90 day histology and gene expression data) and late outcomes (transplant glomerulopathy and graft loss) in positive crossmatch kidney transplants (+XMKTx). Our goal was threefold: first, to confirm that intragraft molecular changes at 12m post-transplant are associated with the observed histologic changes in SLK transplant recipients, compared with KTA transplant recipients; second, to ascertain whether specific molecular pathways/markers that are not accounted for by routine histology are differentially expressed in the kidney allografts of the SLK transplant recipients; and third, to determine whether a molecular signature that is uniquely associated with simultaneous liver transplantation can be identified in kidney allografts.