The cellular landscape of the normal kidney allograft: Main players balancing the alloimmune response
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ABSTRACT:
SUBMITTER: McDaniels J
PROVIDER: S-EPMC11235379 | biostudies-literature | 2022 Jan
REPOSITORIES: biostudies-literature
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Project description:Different types of kidney transplantations are performed worldwide, including biologically diverse donor/recipient combinations, which entail distinct patient/graft outcomes. Thus, proper immunological and non-immunological risk stratification should be considered, especially for patients included in interventional randomized clinical trials. This paper was prepared by a working group within the European Society for Organ Transplantation, which submitted a Broad Scientific Advice request to the European Medicines Agency (EMA) relating to clinical trial endpoints in kidney transplantation. After collaborative interactions, the EMA sent its final response in December 2020, highlighting the following: 1) transplantations performed between human leukocyte antigen (HLA)-identical donors and recipients carry significantly lower immunological risk than those from HLA-mismatched donors; 2) for the same allogeneic molecular HLA mismatch load, kidney grafts from living donors carry significantly lower immunological risk because they are better preserved and therefore less immunogenic than grafts from deceased donors; 3) single-antigen bead testing is the gold standard to establish the repertoire of serological sensitization and is used to define the presence of a recipient's circulating donor-specific antibodies (HLA-DSA); 4) molecular HLA mismatch analysis should help to further improve organ allocation compatibility and stratify immunological risk for primary alloimmune activation, but without consensus regarding which algorithm and cut-off to use it is difficult to integrate information into clinical practice/study design; 5) further clinical validation of other immune assays, such as those measuring anti-donor cellular memory (T/B cell ELISpot assays) and non-HLA-DSA, is needed; 6) routine clinical tests that reliably measure innate immune alloreactivity are lacking.
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Project description:Obesity initiates a chronic inflammatory network linked to perioperative complications and increased acute rejection rates in organ transplantation. Bariatric surgery is the most effective treatment of obesity recommended for morbidly obese transplant recipients. Here, we delineated the effects of obesity and bariatric surgery on alloimmunity and transplant outcomes in diet-induced obese (DIO) mice. Allograft survival was significantly shorter in DIO-mice. When performing sleeve gastrectomies (SGx) prior to transplantation, we found attenuated T cell-derived alloimmune responses resulting in prolonged allograft survival. Administering taurodeoxycholic acid (TDCA) and valine, metabolites depleted in DIO-mice and restored through SGx, prolonged graft survival in DIO-mice comparable with SGx an dampened Th1 and Th17 alloimmune responses while Treg frequencies and CD4+ T cell-derived IL-10 production were augmented. Moreover, in recipient animals treated with TDCA/valine, levels of donor-specific antibodies had been reduced. Mechanistically, TDCA/valine restrained inflammatory M1-macrophage polarization through TGR5 that compromised cAMP signaling and inhibited macrophage-derived T cell activation. Consistently, administering a TGR5 agonist to DIO-mice prolonged allograft survival. Overall, we provide novel insights into obesity-induced inflammation and its impact on alloimmunity. Furthermore, we introduce TDCA/valine as a noninvasive alternative treatment for obese transplant patients.
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Project description:Vitamin D, in addition to its established role in bone metabolism, may regulate the immune system and affect the outcome of allografts.We identified 351 kidney allograft recipients who had serum levels of 25-hydroxyvitamin D (25[OH]D) measured within the first 30 days of transplantation. We evaluated the relationship between the circulating levels of 25(OH)D and acute cellular rejection (ACR), cytomegalovirus (CMV) disease, BK virus nephropathy, and kidney graft function.Vitamin D deficiency (circulating levels of 25[OH]D ?20 ng/mL, defined using The Endocrine Society Clinical Practice 2011 Guideline) was observed in 216 (61.5%) of 351 kidney graft recipients. Vitamin D deficiency was more frequent in female recipients (P=0.007, Fisher exact test) and African American recipients (P<0.001) and was less frequent in preemptive kidney graft recipients (P=0.002). Biopsy-confirmed ACR was more frequent in the vitamin D-deficient group than in the sufficient group (10.2% vs. 3.7%, P=0.04). By multivariable Cox regression analysis, vitamin D deficiency was an independent risk factor for ACR (hazard ratio=3.3, P=0.02). Vitamin D deficiency was not associated with CMV disease, BK virus nephropathy, or kidney allograft function at 1 year. 1,25-Dihydroxyvitamin D3 supplementation initiated within the first 90 days of transplantation was associated with a lesser incidence of ACR compared to no treatment with 1,25-dihydroxyvitamin D3 (5.1% vs. 13.0%, P=0.099).Vitamin D deficiency is an independent risk factor for development of ACR within the first year of kidney transplantation and 1,25-dihydroxyvitamin D3 supplementation may help reduce the occurrence of ACR in the vitamin D-deficient group.
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Project description:Noninvasive biomarkers of kidney allograft status can help minimize the need for standard of care kidney allograft biopsies. Metabolites that are measured in the urine may inform about kidney function and health status, and potentially identify rejection events. To test these hypotheses, we conducted a metabolomics study of biopsy-matched urine cell-free supernatants from kidney allograft recipients who were diagnosed with two major types of acute rejections and no-rejection controls. Non-targeted metabolomics data for 674 metabolites and 577 unidentified molecules, for 192 biopsy-matched urine samples, were analyzed. Univariate and multivariate analyses identified metabolite signatures for kidney allograft rejection. The replicability of a previously developed urine metabolite signature was examined. Our study showed that metabolite profiles can serve as biomarkers for discriminating rejection biopsies from biopsies without rejection features, but also revealed a role of estimated Glomerular Filtration Rate (eGFR) as a major confounder of the metabolite signal.
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Project description:IntroductionKidney transplantation is the optimal treatment for end-stage kidney disease; however, premature allograft loss remains a serious issue. While many high-throughput omics studies have analyzed patient allograft biospecimens, integration of these datasets is challenging, which represents a considerable barrier to advancing our understanding of the mechanisms of allograft loss.MethodsTo facilitate integration, we have created a curated database containing all open-access high-throughput datasets from human kidney transplant studies, termed NephroDIP (Nephrology Data Integration Portal). PubMed was searched for high-throughput transcriptomic, proteomic, single nucleotide variant, metabolomic, and epigenomic studies in kidney transplantation, which yielded 9,964 studies.ResultsFrom these, 134 studies with available data detailing 260 comparisons and 83,262 molecules were included in NephroDIP v1.0. To illustrate the capabilities of NephroDIP, we have used the database to identify common gene, protein, and microRNA networks that are disrupted in patients with chronic antibody-mediated rejection, the most important cause of late allograft loss. We have also explored the role of an immunomodulatory protein galectin-1 (LGALS1), along with its interactors and transcriptional regulators, in kidney allograft injury. We highlight the pathways enriched among LGALS1 interactors and transcriptional regulators in kidney fibrosis and during immunosuppression.DiscussionNephroDIP is an open access data portal that facilitates data visualization and will help provide new insights into existing kidney transplant data through integration of distinct studies and modules (https://ophid.utoronto.ca/NephroDIP).
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Project description:Background Single-cell genomics techniques are revolutionizing our ability to characterize complex tissues. By contrast, the techniques used to analyze renal biopsy specimens have changed little over several decades. We tested the hypothesis that single-cell RNA-sequencing can comprehensively describe cell types and states in a human kidney biopsy specimen.Methods We generated 8746 single-cell transcriptomes from a healthy adult kidney and a single kidney transplant biopsy core by single-cell RNA-sequencing. Unsupervised clustering analysis of the biopsy specimen was performed to identify 16 distinct cell types, including all of the major immune cell types and most native kidney cell types, in this biopsy specimen, for which the histologic read was mixed rejection.Results Monocytes formed two subclusters representing a nonclassical CD16+ group and a classic CD16- group expressing dendritic cell maturation markers. The presence of both monocyte cell subtypes was validated by staining of independent transplant biopsy specimens. Comparison of healthy kidney epithelial transcriptomes with biopsy specimen counterparts identified novel segment-specific proinflammatory responses in rejection. Endothelial cells formed three distinct subclusters: resting cells and two activated endothelial cell groups. One activated endothelial cell group expressed Fc receptor pathway activation and Ig internalization genes, consistent with the pathologic diagnosis of antibody-mediated rejection. We mapped previously defined genes that associate with rejection outcomes to single cell types and generated a searchable online gene expression database.Conclusions We present the first step toward incorporation of single-cell transcriptomics into kidney biopsy specimen interpretation, describe a heterogeneous immune response in mixed rejection, and provide a searchable resource for the scientific community.
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