Project description:Recurrence of focal segmental glomerulosclerosis (rFSGS) after kidney transplantation is a cause of early and accelerated graft loss. Immuneadsorption can alleviate renal dysfunction and suggests that circulating antibodies (Ab) are likely implicated in disease pathogenesis. To evaluate pathogenic Ab in rFSGS, we processed 141 unique serum samples from patients with and without primary rFSGS (n=64) and 34 non-FSGS control, transplanted at five (US and EU) hospitals. 9000 antigens were screened in pre-transplant sera by protein arrays and 10 Ab targeting glomerular antigens were selected for ELISA validation. A panel of 7 Ab (CD40, PTPRO, CGB-5, FAS, P2RY11, SNRPB2 and APOL2) could predict post-transplant FSGS recurrence with 92% accuracy. Pre-transplant elevation of anti-CD40 Ab levels alone had a substantial impact (78% accuracy) on the identification of rFSGS risk after transplantation. Epitope mapping of CD40 with customized peptide arrays and rFSGS sera demonstrated altered immunogenicity of the extracellular CD40 domain in rFSGS. Immunohistochemistry of CD40 demonstrated a differential expression of these antigens in FSGS compared to non-FSGS. Anti-CD40 Ab purified from rFSGS patients were uniquely pathogenic in human podocyte cultures; injection of these Ab resulted in heightened proteinuria, independently and in combination with suPAR in a rodent model, abrogated by injection of monoclonal Ab to CD40. In conclusion, a panel of 7 Ab can identify primary FSGS patients at high risk of recurrence prior to transplantation, allowing for customized therapies and improved patient selection for transplant. Intra-renal CD40 is an important axis of disease pathogenesis, and human trials of anti-CD40 therapies are warranted to evaluate their efficacy in preventing rFSGS and improving graft survival. The purpose of the study was to identify potential auto-Abs associated with rFSGS. We used a discovery set of pre-transplant sera from 20 unique patients with biopsy confirmed diagnosis of primary FSGS as their cause of ESRD, of which 10 had progressed to rFSGS within the first post-transplant year and 10 did not have recurrence of proteinuria or histological disease after transplantation (nrFSGS).
Project description:Recurrence of focal segmental glomerulosclerosis (rFSGS) after kidney transplantation is a cause of early and accelerated graft loss. Immuneadsorption can alleviate renal dysfunction and suggests that circulating antibodies (Ab) are likely implicated in disease pathogenesis. To evaluate pathogenic Ab in rFSGS, we processed 141 unique serum samples from patients with and without primary rFSGS (n=64) and 34 non-FSGS control, transplanted at five (US and EU) hospitals. 9000 antigens were screened in pre-transplant sera by protein arrays and 10 Ab targeting glomerular antigens were selected for ELISA validation. A panel of 7 Ab (CD40, PTPRO, CGB-5, FAS, P2RY11, SNRPB2 and APOL2) could predict post-transplant FSGS recurrence with 92% accuracy. Pre-transplant elevation of anti-CD40 Ab levels alone had a substantial impact (78% accuracy) on the identification of rFSGS risk after transplantation. Epitope mapping of CD40 with customized peptide arrays and rFSGS sera demonstrated altered immunogenicity of the extracellular CD40 domain in rFSGS. Immunohistochemistry of CD40 demonstrated a differential expression of these antigens in FSGS compared to non-FSGS. Anti-CD40 Ab purified from rFSGS patients were uniquely pathogenic in human podocyte cultures; injection of these Ab resulted in heightened proteinuria, independently and in combination with suPAR in a rodent model, abrogated by injection of monoclonal Ab to CD40. In conclusion, a panel of 7 Ab can identify primary FSGS patients at high risk of recurrence prior to transplantation, allowing for customized therapies and improved patient selection for transplant. Intra-renal CD40 is an important axis of disease pathogenesis, and human trials of anti-CD40 therapies are warranted to evaluate their efficacy in preventing rFSGS and improving graft survival.
Project description:Background: Many patients with idiopathic focal segmental glomerulosclerosis (FSGS) develop recurrence of proteinuria after kidney transplantation. Several circulating permeability factors (CPFs) responsible for recurrence have been suggested, but there is no consensus about the identity of CPFs in FSGS. We aimed to find proteins involved in the mechanism of action of the CPF(s) and/or potential biomarkers for the presence of CPF(s). Methods: Cultured human podocytes were exposed to plasma from patients with FSGS with presumed CPF(s), or from (disease) controls. Podocyte proteomes were analyzed by mass spectrometry and differentially expressed proteins were validated using flow cytometry, RT-PCR, and immunofluorescence. Changes in podocyte granularity were examined using flow cytometry, electron microscopy imaging and BODIPY staining. Results: Perilipin-2 protein expression was increased in podocytes exposed to presumed CPF-containing plasmas, which was related to disease state and capacity of plasma to induce granularity in podocytes. Elevated perilipin-2 levels were confirmed at protein and mRNA level. The granules observed in podocytes actually are lipid droplets. Importantly, increased perilipin-2 staining was also detected in glomeruli of the FSGS patients whose active disease plasmas induced lipid droplets in podocytes. Conclusions: Our study demonstrates that presumably CPF-containing plasma from FSGS patients alter podocyte lipid metabolism and increase perilipin-2 protein and lipid droplet accumulation. Future research should address the mechanism underlying CPF-induced alterations in podocyte lipid metabolism in the context of the pathogenesis of (recurrent) FSGS, which ultimately may result in novel leads for treatment.
Project description:Diabetes mellitus (DM) after transplantation remains a crucial clinical problem in kidney transplantation. To obtain insights into molecular mechanisms underlying the development of post-transplant diabetes mellitus (PTDM) and its early impact on glomerular structures, here we comparatively analyze the proteome of histologically normal appearing glomeruli from patients with PTDM from normoglycemic (NG) transplant recipients, and from recipients with pre-existing type 2 DM (PTDM)
Project description:Microarray technology has evolved as a powerful tool over the last decade, to identify biomarkers and study the mechanisms of diseases. We propose a novel application of integrated genomics by combining transcriptional levels with serological antibody profiling after kidney transplantation, with the aim of uncovering the relative immunogenicity of seven different renal compartments after allo-transplantation. Thirty-six paired pre- and post-transplant serum samples were examined from eighteen transplant recipients, across 5,056 protein targets on the ProtoArray V3.0 platform. Normal renal compartment-specific gene expression data from a cDNA platform were re-analyzed and both the cDNA and the ProtoArray platforms were re-annotated to most up-to-date NCBI gene identifiers; 3,835 genes/proteins are measured on both platforms. Antibody levels were ranked for individual patients and the hypergeometric enrichment statistic was applied on mapped compartment-specific expression data. We discovered that after transplantation, in addition to HLA and MICA responses, temporal alloimmune responses are seen against non-HLA antigens specific to different compartments of the kidney, with highest level responses noted against renal pelvis and cortex specific antigens. The renal medulla is of low immunogenicity as none of the outer or inner medulla specific targets generated significant post-transplant antibody responses. Immunohistochemistry confirmed pelvis and cortex specific localizations of selected targeted antigens, supporting the robust nature of this discovery. This study provides a road map of renal compartment-specific non-HLA antigenic targets responsible for generating alloimmune responses, opening the door for clinical correlations with post-transplant dysfunctional states to be determined. Keywords: alloimmune response after kidney transplantation
Project description:Background: Plasmapheresis/rituximab-based desensitization therapy has successfully reduced anti-ABO antibody levels and suppressed antibody-mediated rejection (AMR) in ABO-incompatible (ABOi) kidney transplantation (KT). However, high titers of anti-ABO antibodies in some patients are refractory to standard desensitization, leading to loss of KT opportunities or AMR. Methods: Eculizumab-based desensitization was used to rescue high-titer ABOi KT patients refractory to plasmapheresis/rituximab-based desensitization. Results: The initial titers of anti-ABO IgG antibodies in the two patients were 1:512 and >1:1024; the final pre-transplant titers after desensitization were 1:128 and 1:64. Both patients received eculizumab from the day of KT to two or four weeks post-KT and maintained stable renal function up to one-year post-transplantation without overt infectious complications, despite early episodes of suspicious AMR or borderline T cell-mediated rejection. Molecular phenotype analysis of allograft biopsies using the Banff Human Organ Transplant gene panel revealed that gene expression patterns in the ABOi KT with eculizumab group overlapped with those in the ABOi KT with AMR group more than in the ABOi KT without AMR group, except for complement pathway-related gene expression. Anti-ABO antibody titers decreased to low levels 1–3 months post-transplant in the eculizumab group in parallel with decreasing anti-B-specific B cells at this time point. Conclusions: Short-term eculizumab-based desensitization therapy is promising for rescuing ABOi KT recipients with unacceptably high anti-ABO antibody titers refractory to plasmapheresis-based desensitization therapy.
Project description:Background: Studies recently support that non-HLA antigens could be additional targets of injury in organ transplant recipients, and MICA was associated with an increased risk of graft loss. Methods: A ProtoArray platform was used to study 37 serum samples from 22 unique patients (15 renal recipients and 7 healthy controls). Thirty paired pre- and post-transplant serum samples were analyzed for detection of de novo post-transplant antibody responses in the 15 patients (10 acute rejection (AR), 5 Stable). Probes on ProtoArray and cDNA platforms (GSE: 3931) were re-annotated and compartment specific gene lists were analyzed using the integrated genomics method. Normal and transplant kidney IHC were performed for MICA antigen localization. Results: Mean MICA-Ab (antibody) signal intensity was significantly higher in transplant patients compared with healthy controls and de novo MICA-Ab were detected in 73% transplant patients. The mean post-transplant signal intensity of MICA-Ab was the highest in C4d+AR. Detection of MICA-Ab responses did not correlate with time post-transplantation, but significantly correlated with decline in graft function over the subsequent year. Integrative genomics predicted localization of the MICA antigen to the glomerulus. IHC confirmed cytoplasmic MICA staining solely in glomerular podocytes in normal kidney. In the transplant kidney, infiltrating mononuclear lymphocytes (T, B and NK) in AR had additional MICA staining. Conclusions: MICA can be highly detected regardless of graft dysfunction or AR. The intensity signal of the MICA antibody correlates with subsequent decline in graft function. The MICA antigen localizes to the glomerulus and infiltrating mononuclear cells in AR.
Project description:Background: Studies recently support that non-HLA antigens could be additional targets of injury in organ transplant recipients, and MICA was associated with an increased risk of graft loss. Methods: A ProtoArray platform was used to study 37 serum samples from 22 unique patients (15 renal recipients and 7 healthy controls). Thirty paired pre- and post-transplant serum samples were analyzed for detection of de novo post-transplant antibody responses in the 15 patients (10 acute rejection (AR), 5 Stable). Probes on ProtoArray and cDNA platforms (GSE: 3931) were re-annotated and compartment specific gene lists were analyzed using the integrated genomics method. Normal and transplant kidney IHC were performed for MICA antigen localization. Results: Mean MICA-Ab (antibody) signal intensity was significantly higher in transplant patients compared with healthy controls and de novo MICA-Ab were detected in 73% transplant patients. The mean post-transplant signal intensity of MICA-Ab was the highest in C4d+AR. Detection of MICA-Ab responses did not correlate with time post-transplantation, but significantly correlated with decline in graft function over the subsequent year. Integrative genomics predicted localization of the MICA antigen to the glomerulus. IHC confirmed cytoplasmic MICA staining solely in glomerular podocytes in normal kidney. In the transplant kidney, infiltrating mononuclear lymphocytes (T, B and NK) in AR had additional MICA staining. Conclusions: MICA can be highly detected regardless of graft dysfunction or AR. The intensity signal of the MICA antibody correlates with subsequent decline in graft function. The MICA antigen localizes to the glomerulus and infiltrating mononuclear cells in AR. Pre- and post-transplant serum antibodies were profiled for each patient, using the Invitrogen ProtoArray® Human Protein Microarray v3.0 platform (Invitrogen, Carlsbad, CA). This platform contains 5,056 non-redundant human proteins expressed in a baculovirus system, purified from insect cells and printed in duplicate onto a nitrocellulose-coated glass slide. Each protein is spotted twice on each array, to measure the quality of the signal intensity. Details for experiment processing and analysis follow the previous publication from our group (13). Prospector software was used to retrieve the expression based on immune response profiling of the .gal files.
Project description:Kidney transplant recipients with biopsy-proven microvascular injury (MVI) have increased risk for allograft failure. MVI is often caused by antibody-mediated injury that is resistant to available treatments. Current diagnostic methods are also inadequate, with interobserver variability in traditional pathology reads, variable assessment of circulating donor-specific antibody between HLA laboratories, and peritubular capillary C4d staining. Molecular assessments of kidney biopsies can provide improved sensitivity for diagnosing MVI and other allograft pathology, while improving reproducibility and objectivity. Most molecular classifiers have been based on whole genome sequencing to develop diagnostic tests, but have provided limited therapeutic targets. In this study, we pursued a candidate gene approach to measure WNT pathway genes in residual clinical FFPE biopsies with and without MVI. We focused on the WNT pathway because of previous translational studies that implicated this pathway in chronic renal allograft injury as well as vascular injury in native chronic kidney disease. Case-control study of 95 residual FFPE biopsies with MVI (g+ptc score >= 2, n=50) or Stable (g+ptc score < 2 and no other major abnormalities, n=45). Biopsies were retrieved from a biorepository of over 500 kidney transplant biopsies. We compared expression of 180 WNT pathway genes and 30 custom skipe-in targets (derived from previous studies of endothelial injury in transplantation) between MVI and Stable groups, with correction for multiple comparisons using FDR < 5%. This dataset is part of the TransQST collection.
Project description:Focal and segmental glomerulosclerosis (FSGS) is a severe form of idiopathic nephrotic syn-drome (INS), a glomerulopathy of presumable immune origin and attributed to extrarenal path-ogenic circulating factors. FSGS recurrence (rFSGS) after transplant occurs in 30 to 50% of cases. Direct analysis of patient plasma proteome has been scarcely addressed to date, mainly due to methodological difficulties associated with plasma complexity and dynamic range. In this study, firstly we compared different methods of plasma preparation, secondly we compared the plasma proteome of rFSGS and controls using two preparation methods, and thirdly we analyzed the early proximal signaling events in podocytes subjected to patient plasma, by a combination of phosphoproteomics and lipid raft proteomics (raftomics). By combining immunodepletion and high pH fractionation, we performed a differential proteomic analysis of soluble plasma pro-teins and of extracellular vesicles (EV) obtained from healthy controls, non-INS patient controls, and rFSGS patients (n=4). In both soluble and EV protein sets from rFSGS patients we found a statistically significant increase in a cluster of proteins involved in neutrophil degranulation. A group of lipid binding proteins, generally associated with lipoproteins, was found decreased in the soluble set from rFSGS patients. In addition, three aminoacid transporters involved in mTORC1 activation were found significantly increased in EV from rFSGS. Next, we incubated human podocytes for 30min with 10% plasma from both groups of patients. Phosphoproteomics and raftomics of podocytes revealed profound differences in proteins involved in the mTOR pathway, in autophagy, and in cytoskeleton organization. We analyzed the correlation between the abundance of plasma and plasma-regulated podocyte proteins. The observed changes high-light some of the mechanisms involved in FSGS recurrence and could be used as specific early markers of circulating factor activity on podocytes.