During the event, a specific symposium is held for the EU Train-ESOT that highlights the methodological and statistical risks clinical researchers can face in the field of transplantation. Carmen Lefaucheur, Olivier Aubert, Alexandre Loupy and Yassine Bouatou are invited to speak during this event to present the future of patient care in transplantation.
You can follow the event through social media with the hashtag #ESOT2019 and @ParisTxGroup.
New research conducted by the Paris Translational Research Center for Organ Transplantation team could help clinicians determine which patients will have a disease that usually occurs after a kidney transplant and which are at high risk of transplant failure. The results are published today in the prestigious Journal of the American Society of Nephrology (JASN).
Transplant glomerulopathy was first described and characterized 50 years ago. It is a disease associated with the loss of a kidney transplant and common after a transplant. It affects the functional units (i. e. glomeruli) of the transplanted kidney. There is currently no treatment for this heterogeneous disease.
Sunday September 24, 2017 1/ MOLECULAR CORRELATES OF ENDOTHELIAL MTOR ACTIVATION IN HEART TRANSPLANT RECIPIENTS
Session: “ Basic and translational immunology” (17:45 to 18:45) Location: Room 118 + 119 – 18:29 M Racapé, A Loupy, J Reeve, J Venner , R Guillemain, L Hidalgo, C Lefaucher, X Jouven, P Bruneval, J Duaong Van Huyen, P Halloran Background The detection of phosphorylated effectors of the mTOR pathway such as phosphorylated-S6RP in endothelial cells by immunohistochemistry (IHC) has been associated with Antibody-Mediated allograft Rejection (AMR). The aim of this study was to evaluate the molecular phenotype related to the endothelial detection of pS6RP in heart transplant recipients. Methods This case-control study included 41 heart transplant patients from four French referral centers with biopsy proven antibody-mediated rejection (pAMR+) and a matched control group of 30 patients without rejection (pAMR0) based on the updated ISHLT classification. From these patients, 94 endomyocardial biopsies (EMB) had adequate material for microarray analysis and endothelial expression analysis of pS6RP by IHC. We also determined the allograft gene expression profile using the ABMR molecular score in addition to pathogenesis-based transcripts reflecting endothelial activation (DSAST and ENDAT), macrophage burden (QCMAT), gamma-interferon response (GRIT) and NK-cell burden (NKB) (http://atagc.med.ualberta.ca). Results Among the 94 EMBs included in the main analyses, 50 were pAMR+ (53.2%) and 44 (46.8%) were pAMR0 normal EMBs. Endothelial expression of pS6RP was observed in 27/50 (54%) of pAMR+ biopsies and 12 out of 44 normal biopsies (27.3%, Fischer's exact: p=0.012). As compared with biopsies without pS6RP labeling, biopsies with pS6RP staining showed increased expression of DSAST (Mann-Whitney: p<0.0001), ENDAT (p=0.0009), QCMAT (p=0.0046), NKB (p=0.0001), GRIT (p=0.0008) and increased ABMR molecular score reflecting AMR injury (p=0.0001). Conclusion Endothelial activation of mTOR pathway is associated with AMR and increased expression in transcripts reflecting endothelial activation, macrophage burden, microcirculation and NK burden. Our results suggest the importance of the mTOR pathway activation in AMR injury and the potential interest of using mTOR inhibitors in this setting. Dr Olivier Aubert was granted by the French National Research Institute for Scientific Excellence9/12/2017
 Dr Olivier Aubert was among the 4 young MD investigators to be granted by the French National Research Institute for Scientific Excellence (INSERM-Bettencourt)
More details in: https://www.fondationbs.org/fr/la-fondation/les-actualites/jeunes-medecins-chercheurs-le-temps-retrouve  Abstract Addressing the causes of kidney allograft-accelerated aging is an important challenge for improving long-term transplant outcomes. Here we investigated the role of circulating donor-specific anti-HLA antibodies (HLA-DSAs) in the development and the progression of kidney allograft fibrosis with inclusion of traditional risk factors for allograft fibrosis. We prospectively enrolled 1539 consecutive kidney recipients transplanted in two centers and assessed interstitial fibrosis and tubular atrophy (IF/TA) in biopsies performed at one year post-transplantation. The HLA-DSAs and all traditional determinants of IF/TA were recorded at transplantation and within the first year post-transplantation, including histological diagnoses in 2260 "for cause" biopsies. This identified 498 (32%) patients with severe IF/TA (Banff IF/TA grade 2 or more). HLA-DSAs were significantly associated with severe IF/TA (adjusted odds ratio, 1.53; 95% confidence interval 1.16-2.01) after including 37 determinants. HLA-DSAs remained significantly associated with severe IF/TA in patients without antibody-mediated rejection (adjusted odds ratio 1.54; 1.11-2.14). HLA-DSAs were the primary contributor, being involved in 11% of cases, while T cell-mediated rejection, calcineurin-inhibitor toxicity, acute tubular necrosis, pyelonephritis, and BK virus-associated nephropathy were involved in 9%, 8%, 6%, 5%, and 4% of cases, respectively. One hundred fifty-four patients with HLA-DSA-associated severe IF/TA showed significantly increased microvascular inflammation, transplant glomerulopathy, C4d deposition in capillaries, and decreased allograft survival compared to 344 patients with severe IF/TA without HLA-DSAs. Three hundred seventy-eight patients with post-transplant HLA-DSAs exhibited significantly accelerated progression of IF/TA compared to 1161 patients without HLA-DSAs in the biopsies performed at one year post-transplant and beyond. Thus, circulating HLA-DSAs are major determinants of premature and accelerated allograft fibrosis acting independently of traditional risk factors and antibody-mediated rejection. Authors: Gosset C, Viglietti D, Rabant M, Vérine J, Aubert O, Glotz D, Legendre C, Taupin JL, Duong Van-Huyen JP, Loupy A, Lefaucheur C.
Abstract Antibody-mediated rejection (ABMR) can occur in patients with preexisting anti-HLA donor-specific antibodies (DSA) or in patients who develop de novo DSA. However, how these processes compare in terms of allograft injury and outcome has not been addressed. From a cohort of 771 kidney biopsy specimens from two North American and five European centers, we performed a systematic assessment of clinical and biologic parameters, histopathology, circulating DSA, and allograft gene expression for all patients with ABMR (n=205). Overall, 103 (50%) patients had preexisting DSA and 102 (50%) had de novo DSA. Compared with patients with preexisting DSA ABMR, patients with de novo DSA ABMR displayed increased proteinuria, more transplant glomerulopathy lesions, and lower glomerulitis, but similar levels of peritubular capillaritis and C4d deposition. De novo DSA ABMR was characterized by increased expression of IFNγ-inducible, natural killer cell, and T cell transcripts, but less expression of AKI transcripts compared with preexisting DSA ABMR. The preexisting DSA ABMR had superior graft survival compared with the de novo DSA ABMR (63% versus 34% at 8 years after rejection, respectively; P<0.001). After adjusting for clinical, histologic, and immunologic characteristics and treatment, we identified de novo DSA ABMR (hazard ratio [HR], 1.82 compared with preexisting DSA ABMR; 95% confidence interval [95% CI], 1.07 to 3.08; P=0.03); low eGFR (<30 ml/min per 1.73 m2) at diagnosis (HR, 3.27; 95% CI, 1.48 to 7.23; P<0.001); ≥0.30 g/g urine protein-to-creatinine ratio (HR, 2.44; 95% CI, 1.47 to 4.09; P<0.001); and presence of cg lesions (HR, 2.25; 95% CI, 1.34 to 3.79; P=0.002) as the main independent determinants of allograft loss. Our findings support the transplant of kidneys into highly sensitized patients and should encourage efforts to monitor patients for de novo DSA.   2017 American Transplant Congress (ATC) April 29-May 3, 2017 in Chicago, IL, USA Sunday April 30, 2017
1/ Long-term outcome of antibody-mediated rejection due to pre-existing vs. de novo DSA in kidney allograft recipients. Session : « Concurrent Session : Assessing Risk for Antibody-Mediated Rejection in Kidney Transplant Recipients » (2:30 PM-4:00 PM) Location : E354a – 3:42 pm O Aubert, C Lefaucheur, S Higgins, L Hidalgo, J-P Duong van Huyen, D Viglietti, X Jouven, D Glotz, C Legendre, P Halloran and A Loupy. Background Antibody-mediated rejection (ABMR) can occur in patients with pre-existing anti-HLA donor-specific antibodies (DSA) or in patients who develop de novo DSA. However, how these processes compare in terms of kidney allograft outcome has not been addressed. The paucity of data is related to the heterogeneity between cohorts and the absence of systematic graft assessment that permits to adjust on the potential confounders between diseases. Methods From a cohort of 771 kidney biopsies from two North-American and five European centers, we included all patients with a diagnosis of ABMR. We used an integrative analysis strategy comprising a systematic assessment of clinical-biological parameters, transplant characteristics, histopathology, immunohistochemistry, type of treatment and circulating anti-HLA DSA assessment at day of transplant and at the time of ABMR for all patient using Luminex SA assay. Results Among the 205 patients with ABMR, 103 (50%) were related to pre-existing DSA while 102 (50%) were related to de novo DSA. ABMR due to de novo DSA displayed increased proteinuria and transplant glomerulopathy lesions, lower glomerulitis, but similar peritubular-capillaritis Banff scores and C4d-deposition than patients with ABMR due to pre-existing DSA. Graft survival was superior in the group of patients with pre-existing DSA ABMR compared to patients with de novo DSA ABMR (graft survival at 8 years post ABMR of 63% vs 35% respectively, p<0.001). After adjusting for clinical, histological, immunological characteristics and treatment, we identified de novo DSA ABMR (HR=1.82 compared to pre-existing DSA ABMR); low (<30mL/min/1.73m2) eGFR at diagnosis (HR=3.273; p<0.001); ≥0.30g/g proteinuria/creatinine ratio (HR=2.44; p<0.001); and presence of cg-lesions (HR=2.25; p=0.002) as the main independent determinants of allograft loss. The inferior graft survival of patients with de novo DSA ABMR compared to pre-existing remained significant irrespective of type of treatment (ST/PP/IVIG), time of diagnosis and degree of allograft injury and atrophy scarring at the time of diagnosis. Conclusion This study is the first to assess combined cohorts of ABMR due to pre-existing DSA and de novo DSA. We found that these diseases have distinct prognosis with an acceptable and superior allograft survival in patients with preexisting/persisting DSA related ABMR compared to ABMR due to de novo DSA. This supports the transplantation of highly-sensitized patients but also encouraging efforts to monitor patients for de novo DSA and avoidance of minimization strategies. Monday, May 1, 2017 2/ Gene Expression Profiling For The Identification And Classification of Antibody-Mediated Heart Rejection Session : “Concurrent Session: Heart Transplantation: Antibodies and Outcomes” (2:30 PM-4:00 PM) Location : E271b – 2:30 pm A Loupy, JP Duong Van Huyen, L Hidalgo, J Reeve, M Racapé, O Aubert, J Venner, D Viglietti, P Bruneval, C Lefaucheur, PF Halloran Antibody-mediated rejection is a major determinant of heart allograft loss. However, the specific effects of anti-HLA antibodies on heart allograft injury have not been addressed at a population level. We prospectively monitored 617 heart transplant recipients referred from four French heart transplant centers (January 1st 2006 - January 1st 2011) for antibody-mediated rejection. We compared patients with antibody-mediated rejection (n=50) to a matched control group of 50 patients without antibody-mediated rejection. We characterized all patients using histopathology (ISHLT 2013), immunostaining, and circulating anti-HLA DSA at the time of biopsy, together with systematic gene expression assessments of their allografts using microarrays. The principal effector cells were also evaluated by in vitro human cell cultures. We studied an additional external validation cohort of 98 heart recipients transplanted in Edmonton, Alberta Canada including 27 pAMR cases and 71 controls. A total of 240 heart transplant EMB were assessed. Antibody-mediated heart rejection showed a distinct pattern of injury characterized by endothelial activation with microcirculation inflammation by monocytes / macrophages and NK-cells, as well as very selective changes in endothelial/angiogenesis and NK cell transcripts, including CD16A signaling and select IFNG-inducible genes. The antibody-mediated heart rejection selective gene sets discriminated with great accuracy patients with antibody-mediated rejection from those without and included NK transcripts (AUC=0.87), endothelial activation transcripts (AUC=0.80), macrophage transcripts (AUC=0.86) and transcripts involved in the IFNG response (AUC=0.84, p<0.0001 for all comparisons). These 4 gene sets showed increased expression with increasing antibody-mediated heart rejection ISHLT grades (p<0.001) and association with class I and class II circulating anti-HLA DSA levels. The unsupervised PCA analysis projected the antibody-mediated rejection gene sets and demonstrated a high proportion of molecular inactive pAMRI+ compared with a significant molecular overlap between pAMR1H+ and full-blown pAMR2-3 cases reclassifying 25% of antibody-mediated heart rejection cases. Endothelial activation transcripts, interferon gamma transcripts and NK transcripts showed association with chronic allograft vasculopathy. We further confirmed that the molecular architecture and selective antibody-mediated rejection transcripts together with gene set discrimination capacity for antibody-mediated rejection were highly conserved in the external validation cohort. Antibody-mediated heart rejection is mainly driven by the NK burden, endothelial activation, macrophage burden and IFNG effects. Molecular intragraft measurements for these specific pathogenesis-based transcripts classify antibody-mediated rejection with great accuracy and correlate with the degree of injury and disease activity. This study illustrates the clinical potential of a molecular microscope approach in heart transplant rejection. 3/ Circulating Donor-Specific Anti-HLA Antibodies Accelerate the Progression of Interstitial Fibrosis in Kidney Allografts Session : “Concurrent Session: Long Term Kidney Graft Survival I” (2:30 PM-4:00 PM) Location E450a – 2:30 pm C Gosset, D Viglietti, M Rabant, E Pillebout, A Bouquegneau, JL Taupin, D Glotz, C Legendre, JP Duong Van-Huyen, A Loupy, C Lefaucheur Interstitial fibrosis represents a major cause of kidney allograft failure. Addressing the causes of accelerated ageing of kidney allografts represents an important challenge to improve long-term transplant outcomes. We investigated the role of donor-specific anti-HLA antibodies (DSA) in the progression of kidney allograft interstitial fibrosis. We prospectively enrolled 913 kidney recipients transplanted between 2004 and 2010 in two centers in Paris. All patients were assessed for allograft interstitial fibrosis on biopsies performed at Day 0 and at 1 year after transplantation using the IF/TA Banff grade. We also integrated all the “for cause” biopsies performed in the first year post transplant (N=1035) and after the first year (N=784, median time of biopsies 18.4 months; IQR, 13.3-40.4). All patients were systematically screened for DSA by Luminex SAB at the time of transplantation (Day 0) and within the first year post-transplantation. The progression of IF/TA within the first year post-transplantation was evaluated by the difference between the 1-year and Day-0 IF/TA grades (∆IF/TA). The progression of IF/TA over the long term was modelled using mixed-effect regression model. The distribution of IF/TA on pre-implantatory biopsies (N=913) was: 726 (80%) patients had IF/TA0, 145 (15%) IF/TA1, 36 (4%) IF/TA2 and 6 (1%) IF/TA3 as compared to 325 (35%), 263 (29%), 173 (19%), and 152 (17%) on 1-year biopsies (N=913), respectively (P<0.001). Over the first year, 507 (56%) patients presented progression of IF/TA (∆IF/TA>0). Patients with Day-0 DSA (N=198) showed increased progression of fibrosis within the first year (∆IF/TA of 1.08±1.15) as compared to patients without Day-0 DSA (N=715, 0.86±1.12) (P=0.016). Patients with post-transplant DSA (preformed or de novo) (N=236) exhibited accelerated progression of IF/TA as compared to patients without post-transplant DSA (N=677) (P for interaction between DSA and time=0.0078) when integrating the biopsies performed at 1-year post transplant and beyond. Pre-transplant circulating anti-HLA DSA increase premature allograft fibrosis and post-transplant DSA accelerate the progression of allograft fibrosis over the long term. 4/ Composite Prognostic Score Improves Clinical Benefit in Kidney Recipients Receiving Standard of Care Therapy For Antibody-Mediated Rejection Session : “Concurrent Session: Treatment of Antibody Mediated Rejection in Kidney Transplant Recipients” (2:30 PM-4:00 PM) Location : E354a – 2:42 pm D Viglietti, A Loupy, O Aubert, E Pillebout, C Gosset, C Legendre, D Glotz, C Lefaucheur The current strategy (SOC) for antibody-mediated rejection (AMR) treatment is based on plasma exchange (PE) and intravenous immunoglobulins (IVIG). However, there is a substantial heterogeneity in AMR patients’ prognosis after SOC with wide variations being observed in the rates and patterns of progression to allograft failure. We investigated whether the use of a prognostic score in kidney recipients receiving AMR SOC therapy provides improvement in clinical-decision making. We prospectively enrolled 2666 consecutive kidney recipients transplanted between 2004 and 2012 in two Paris centers and we included in the present study all of the patients diagnosed with active AMR who received standardized treatment including PE (x4-5) and high-dose IVIG (2 g/kg) repeated every 3 weeks for 3-4 rounds. Patients were systematically assessed at the time of diagnosis and 3 months post-treatment for clinical data (eGFR and proteinuria), histological characteristics (allograft biopsy) and circulating anti-HLA DSA by Luminex SAB. An AMR prognostic score was derived from multivariate Cox model including the most relevant clinical, histological and immunological parameters for allograft loss assessed at the time of AMR diagnosis or related to the response to SOC therapy. The net clinical benefit of the AMR prognostic score was assessed by decision curve analysis. We included 284 patients with biopsy-proven acute or chronic active AMR who received SOC treatment. The 6-year death-censored kidney allograft survival after antibody-mediated rejection was 69.2% (95%CI=61.3-75.9). The independent predictors of allograft loss were: eGFR at AMR diagnosis (HR, 0.93; 95%CI, 0.90-0.95; P<0.001), presence of IF/TA at AMR diagnosis (HR, 2.44; 1.36-4.37; P=0.003), change in eGFR after treatment (HR, 0.24; 95%CI, 0.16-0.35; P<0.001), change in ptc Banff score after treatment (HR, 1.50; 95%CI, 1.16-1.93; P=0.002) and change in donor-specific anti-HLA antibody MFI level after treatment (HR,1.30; 95%CI, 1.11-1.52; P=0.001). The AMR prognostic score derived from the multivariate Cox model for allograft loss showed good discrimination (C-statistic, 0.84; 95% bootstrap percentile CI, 0.80-0.89). Decision-making after AMR SOC based on the AMR prognostic score provided greater net clinical benefit to patients (across a range of risks of allograft loss from 1% to 96%) than considering patients on the same level of risk. The initiation of a second-line therapy based on the AMR prognostic score (for a risk threshold of allograft loss of 20% at 6 years after AMR) would lead to treat 11 patients who will lose their graft in the absence of clinical intervention per 100 patients receiving AMR SOC while not treating patients who will not lose their graft. The use of an accurate composite prognostic score based on clinical, histological and immunological parameters in kidney recipients receiving SOC therapy for AMR improved clinical decision-making. Further studies are needed to define the efficacy and the safety of second-line strategies in patients with AMR at high risk of allograft. 5/ Complement Activating Anti-HLA Antibodies: Identification of Specific Histo-molecular Phenotype of Rejection for Complement-Targeting Therapy Session : “Concurrent Session: Treatment of Antibody Mediated Rejection in Kidney Transplant Recipients” (2:30 PM-4:00 PM) Location : E354a – 2:54 pm C Lefaucheur, B Sis, D Viglietti, L Hidalgo, O Aubert, C Gosset, D Glotz, C Legendre, A Zeevi, P Halloran, A Loupy Addressing the heterogeneity of antibody-mediated allograft rejection by identifying phenotypes based on pathophysiology is critical for personalized care and improving outcomes in transplantation. Complement-binding anti-HLA antibodies (DSA) have been associated with impaired transplant outcome. We investigated whether circulating complement-binding DSA induce specific rejection phenotype and influence response to complement-targeting treatment. We prospectively enrolled 931 consecutive kidney recipients transplanted between 2011 and 2014 in two Paris centers, with systematic screening for the presence of circulating in the first year post-transplantation. All patients underwent allograft biopsy at the time of detection of post-transplant anti-HLA DSA. The allograft rejection phenotypes were assessed by histopathology, immunochemistry, and allograft gene expression analyses using microarray. A model of fully MHC-mismatched male CBA (H-2k) kidneys transplanted into B6.RAG1-/- (H-2b) immunodeficient mice with adoptive transfer of complement and non-complement-binding DSA was studied. The effect of complement inhibition therapy (Eculizumab) on allograft injury phenotype was assessed in two prospective studies (N=70). The histo-molecular phenotype of complement-activating DSA allograft rejection (N=44, 28% of DSA patients) was characterized by increased microvascular infiltration by NK cells (3.9±1.5 vs. 0.4±0.2 NK cells per 10 consecutive high-power fields; P<0.001), monocyte/macrophages (5.8±2.7 vs. 2.4±1.9 monocytes/macrophages per peritubular capillary and 2.2±1.5 vs. 0.9±0.7 monocytes/macrophages per glomeruli; P<0.001 for both comparisons), greater prevalence of complement deposition (63% vs. 19%; P<0.001), and selective changes in allograft gene expression including interferon-gamma and endothelial activation (CXCL11; FC, 2.48; P=0.01; CCL4; FC, 1.94; P=0.01; MS4A6A; FC, 1.89; P=0.002; MS4A7; FC, 1.87; P=0.002; GBP1; FC 2.13; P=0.002) as compared with patients with non-complement binding DSA (N=113; 72% of DSA patients). This phenotype was distinct from that of patients with non-complement binding DSA and patients without DSA in unsupervised hierarchical clustering and principal component analysis. Mice receiving complement-binding DSA reproduced the human complement activating antibody-mediated histo-molecular allograft rejection phenotype. Eculizumab specifically abrogated the histo-molecular phenotype induced by complement-binding DSAs and showed no effect on allograft injury in patients with non-complement-binding DSA. Circulating complement-binding anti-HLA DSA induce a distinct histo-molecular phenotype of kidney allograft rejection that can be specifically reversed by complement inhibition therapy. 6/ Meta-Analysis of Clinical Significance of Complement Activating Anti-HLA DSA in Kidney Transplantation Session : «Concurrent Session: Antibody Mediated Rejection in Kidney Transplant Recipients: Pathophysiology and Epidemiology» (4:30 PM- 6:00PM) Location : E354a – 4:42pm A. Bouquegneau, C. Loheac, C. Ulloa, O. Aubert, D. Viglietti, JP. Empana, P. Jabre, X. Jouven, C. Lefaucheur and A. Loupy Donor-specific anti-HLA antibodies (DSA) are currently recognized as the major limitation to access transplantation and the first cause of late transplant failures. The effect of complement activating DSA on allograft rejection and graft loss has been diversely reported with varying amplitudes between studies. We report the results of a systematic review and meta-analysis of complement activating DSA and their association with graft outcomes in renal transplant recipients. We searched on PubMed, Elsevier Science Direct, Cochrane and EMBASE databases using the following search terms “kidney transplantation, complement-activating DSA, IgG subclass, C1q, C4d, C3d, graft survival and antibody-mediated rejection”. A total of 825 records published between 2004 and 2016 were identified by the search procedure. Duplicate records were removed. We also eliminated case-reports, abstracts, reviews and studies including less than 10 patients. We included studies using single–antigen flow bead techniques. Studies focusing on non-DSA were excluded. The primary outcome was graft survival and the secondary outcome was antibody-mediated rejection rate. The search identified 34 cohort studies comprising a total of 7.293 kidney transplant patients. Studies with available data on primary and secondary outcomes were finally used in the complete meta-analysis, summing up 21 studies and 5.592 patients. Together, these studies demonstrate that patients with post transplant circulating complement activating anti-HLA DSA defined by C1q, C4d, C3d binding capacity or IgG3 subclass show an increased risk of antibody-mediated rejection with a pooled HR of 8.40 (95%CI: 5.21–13.56) and an increase risk of graft loss with a pooled HR of 4.88 (95%CI: 4.03–5.91) and i2 of 58.5%. [Figure 1] Complement activating DSA are strongly associated with increased risk of antibody-mediated graft rejection and impaired long term allograft survival. Future studies are needed to define the place of complement activating DSA in the clinical-decision making for kidney transplant recipients. Tuesday, May 2, 2017 7/ Specific Gene Expression Signature of Complement-Activating Donor Specific Anti-HLA Antibody-Mediated Rejection in Kidney Allografts Session : “Concurrent Session: Diagnosis of Antibody Mediated Rejection in Kidney Transplant Recipients” (2:30 PM-4:00 PM) Location : E354a – 3:06 pm C Lefaucheur, D Viglietti, L Hidalgo, O Aubert, C Gosset, A Zeevi, P Halloran, A Loupy Complement-binding donor-specific anti-HLA antibodies (DSA) have demonstrated higher rejection rate and decreased allograft outcome. However, their specific effects on antibody-mediated rejection pathogenesis have not been identified. We investigated whether the complement binding capacity of circulating DSA is associated with specific gene expression signature in the allograft. We prospectively enrolled 931 consecutive kidney recipients transplanted between 2011 and 2014 in two Paris centers, with systematic screening for the presence of circulating DSA in the first year post-transplantation. We assessed DSA characteristics, including specificity, mean fluorescence intensity (MFI), C1q-binding capacity and IgG1-4 subclasses using Luminex SAB assays. All patients underwent allograft biopsy at the time of detection of post-transplant anti-HLA DSA to assess allograft gene expression using unsupervised microarray analysis. We compared the intragraft gene expression in patients with C1q-binding and non-C1q-binding DSA for 9954 genes after IQR filtering. The relative importance of the top 50 genes for discriminating DSA C1q-binding status with respect to conventional histology parameters was determined using random forests. We identified 157 (17%) patients with circulating anti-HLA DSA detected in the first year after transplantation, 44 (28%) with complement-binding anti-HLA DSA, and 113 (72%) with non-complement-binding anti-HLA DSA. Patients with complement-binding anti-HLA DSA showed higher MFI levels (9483±747 vs. 2978±278; P<0.001) and greater prevalence of IgG1 (96% vs. 62%; P<0.001) and IgG3 (57% vs 17%; P<0.001) subclasses than patients with non-complement-binding anti-HLA DSAs. Among the 9954 inter-quartile range filtered transcripts that were most significantly expressed in the C1q-binding anti-HLA DSA patients, the transcripts most associated with C1q-binding anti-HLA DSAs were composed primarily of NK selective transcripts and NK genes; endothelial genes; interferon gamma genes; macrophage genes; and effector T cell genes. We defined a highly discriminative set of 5 individual genes for C1q-binding anti-HLA DSA status: CXCL11, CCL4, MS4A6A, GBP1 and MS4A7. The 5-gene set capacity to predict the C1q-binding status of anti-HLA DSA outperformed that of conventional histology: AUC of 0.85 vs. 0.76, respectively, P=0.006. The 5-gene set was associated with the C1q-binding capacity of DSA independently of DSA MFI level and IgG subclass composition. The integration of the 5-gene set to conventional histology parameters in unsupervised hierarchical clustering and principal component analysis allowed identifying a distinct pattern of allograft injury reflecting the complement-binding capacity of DSA. We identified a specific gene expression signature of kidney allograft injury related to the complement-binding capacity of circulating DSA that outperformed the conventional histology evaluation. 8/ Absence of independent and additional predictive ability of preimplantation kidney allograft biopsies for long-term outcome: Population based study Session : “Concurrent Session: Kidney Optimizing Donor/Recipient Selection and Matching” (2:30 PM-4:00 PM) Location : E450a – 3:06 pm O Aubert, D Viglietti, C Loheac, M Rabant, C Gosset, J-P Duong van Huyen, D Glotz, C Legendre, C Lefaucheur and A Loupy. Background A significant number of kidneys are discarded worldwide due to the suboptimal use of large kidney resources. The mean cause is the result of the preimplantation biopsy without clear evidence that its results are associated with long-term allograft survival. Methods We included patients who underwent kidney transplantations from a deceased donor in 2 French referral centers between January 1, 2004 and January 1, 2011 where preimplantation are routinely performed and graded by nephro-pathologists. All the patients with preimplantation biopsy were included. A systematic assessment of donor, recipient, and transplant clinical characteristics, a preimplantation biopsy and an evaluation of baseline circulating donor-specific anti-HLA antibody (DSA) levels were performed. Results: A total of 882 patients were included in the study. A total of 352/882 (40%) transplantations were performed using ECD kidneys and a total of 143/882 (16%) had an anti-HLA DSA at the day of transplantation. The mean recipient age was 49.98 ± 13.08 years. The mean follow-up time after transplantation was 6.56 ± 2.37 years. After adjusting for donor, recipient, and transplant characteristics as well as for preimplantation biopsy findings (including the atrophy-fibrosis (IFTA), percentage of sclerotic glomeruli, arteriosclerosis (cv Banff score) and arteriolar hyalinosis scores (ah Banff score) and baseline immunological parameters, we identified the KDRI score (hazard ratio (HR)=2.17; 95% confidence interval (CI), (1.31 to 3.46); p=0.002) and the presence of circulating anti-HLA DSA on the day of transplantation (HR=2.89; 95% CI, (1.95 to 4.27); p<0.0001) as the main independent determinants of long-term allograft loss. None of the preimplantation biopsy findings showed independent association with the kidney allograft survival. Conclusions Preimplantation biopsy assessment does not provide independent and additional predictive ability for long-term allograft outcome at a population level in deaceased donor program. The current practice of discarding kidneys based on preimplantation biopsy findings may not be optimal for decision-making and is a barrier to the decrease in the rate of discarded kidneys. 9/ Identifying the specific causes and the determinants of outcome in kidney recipients with Transplant Glomerulopathy: a multicenter study. Session : “Concurrent Session : Kidney General Outcomes” (4 :30 PM-6:00 PM) Location : E354a – 4 :54 pm O Aubert, S Higgins, P Campbell, C Loheac, D Viglietti, D Glotz, Ch Legendre,B Sis, C Lefaucheur, JP Duong and A Loupy. Background Understanding the specific causes of TG and its long-term consequences at population scale is lacking. Methods This study includes all kidney allograft biopsies performed between January 2004 and January 2014 in three French referral centers and one Canadian center showing TG (Banff cg score≥1 by light microscopy). All TG cases were extensively phenotyped and systematically assessed using light microscopy, immunohistochemistry (IH), immunofluorescence (IF), together with circulating anti-HLA-DSA at the time of biopsy. Results Among the 8207 post-transplant allograft biopsies performed during the inclusion period, 559 (6.8%) had double contours and corresponded to 392 patients. Three overlapping etiologies accounted for 467 (84%) cases. 417 biopsies showed alloantibodies-mediated injury (75%), 91 biopsies showed TMA (16%), 65 showed MPGN (12%), while 92 cases (17%) remained equivocal with no specific lesions identified by the pathologist (Figure 1). The median time to first cg lesion occurrence after transplantation was 32.7 months (IQR: 12.0–77.9). Kidney allograft survival after TG diagnosis was 70% at 3 years, 59% at 5 years and 41% at 8 years. The median time of allograft loss after TG diagnosis was was 3.3 years (IQR: 1.5-5.5) (figure 2). After adjusting for donor, recipient and transplant characteristics, immunological and histological parameters, we identified the following independent factors associated with long-term allograft survival in patients with TG: eGFR (HR:0.96; IC95%(1.10-0.98); p<0.0001) and proteinuria level (HR:2.17; IC95%(1.78-2.66); p<0.0001) at the time of biopsy, deceased donor (HR:1.64; IC95%(1.11-2.42); p=0.0139), delay between transplantation and TG diagnosis (HR:1.34; IC95%(1.18-1.51); p<0.0001) and endarteritis Banff scores (HR:1.82; IC95%(1.15-2.88); p=0.0018). Conclusion Using a large cohort of kidney recipients with a diagnosis of TG and a systematic phenotyping, we identify three overlapping pathways in TG: ABMR, TMA and MPGN. The identification of the main independent determinants of TG prognosis may help improving risk stratification and define specific causes and disease process in patients with TG. 10/ Determinants of Severe Interstitial Fibrosis in Kidney Allografts: Major Impact of Circulating Donor-Specific Anti-HLA Antibodies Session : “Concurrent Session: Long Term Kidney Graft Survival II” (4:30 PM-6:00 PM) Location : E450a – 4:54 pm C Gosset, D Viglietti, M Rabant, E Pillebout, JL Taupin, D Glotz, C Legendre, JP Duong Van-Huyen, A Loupy, C Lefaucheur Interstitial fibrosis represents a major cause of kidney allograft failure. We investigated the independent contribution of circulating donor-specific anti-HLA antibodies (DSA) in the development of severe kidney allograft fibrosis with integration of traditional risk factors for allograft fibrosis. We prospectively enrolled 1539 consecutive kidney recipients transplanted between 2004 and 2010 in two Paris centers, with systematic assessment of allograft fibrosis using the IF/TA Banff score on biopsies performed at 1-year post-transplantation. We considered all of the traditional determinants of allograft fibrosis reported in the literature, recorded at the time of transplantation and in the first year after transplantation. We also integrated DSA assessment and all the histologic diagnoses (“for cause” biopsies; N=1804) performed in the first year after transplantation. We identified 498 (32%) patients with severe IF/TA (Banff grade≥2). DSA were associated with severe IF/TA at 1-year post transplant (adjusted OR, 1.53; 95%CI, 1.16-2.01; P=0.002), independently of the traditional determinants, including: T cell-mediated rejection, antibody-mediated rejection, BK virus-associated nephropathy, calcineurin inhibitor toxicity, initial disease recurrence, pyelonephritis, acute tubular necrosis, donor and recipient baseline parameters, and transplant characteristics. DSA remained associated with severe IF/TA even in patients without episode of antibody-mediated rejection (OR, 1.47; 95%CI, 1.10-1.96; P=0.008). Patients with DSA-associated severe IF/TA (N=154) showed increased microvascular inflammation (P<0.001), transplant glomerulopathy (P<0.001), C4d deposition in capillaries (P<0.001) and decreased allograft survival (P<0.001) as compared to patients with severe IF/TA without DSA. Among the modifiable risk factors for severe IF/TA, DSA were found to be the first contributor, being involved in 11% of cases while T cell-mediated rejection, calcineurin inhibitor toxicity, acute tubular necrosis, pyelonephritis and BK virus-associated nephropathy were involved in 9%, 8%, 6%, 5%, and 4% of cases, respectively. Circulating anti-HLA DSA are major contributor to severe allograft interstitial fibrosis independent of traditional risk factors and of antibody-mediated rejection.
Abstract
Halloran PF, Reeve J, Akalin E, Aubert O, Bohmig GA, Brennan D, Bromberg J, Einecke G, Eskandary F, Gosset C, Duong Van Huyen JP, Gupta G, Lefaucheur C, Malone A, Mannon RB, Seron D, Sellares J, Weir M, Loupy A. The authors conducted a prospective trial to assess the feasibility of real time central molecular assessment of kidney transplant biopsy samples from 10 North American or European centers. Biopsy samples taken 1 day to 34 years posttransplantation were stabilized in RNAlater, sent via courier overnight at ambient temperature to the central laboratory, and processed (29 h workflow) using microarrays to assess T cell- and antibody-mediated rejection (TCMR and ABMR, respectively). Of 538 biopsy samples submitted, 519 (96%) were sufficient for microarray analysis (average length, 3 mm). Automated reports were generated without knowledge of histology and HLA antibody, with diagnoses assigned based on Molecular Microscope Diagnostic System (MMDx) classifier algorithms and signed out by one observer. Agreement between MMDx and histology (balanced accuracy) was 77% for TCMR, 77% for ABMR, and 76% for no rejection. A classification tree derived to provide automated sign-outs predicted the observer sign-outs with >90% accuracy. In 451 biopsy samples where feedback was obtained, clinicians indicated that MMDx more frequently agreed with clinical judgment (87%) than did histology (80%) (p = 0.0042). In 81% of feedback forms, clinicians reported that MMDx increased confidence in management compared with conventional assessment alone. The authors conclude that real time central molecular assessment is feasible and offers a useful new dimension in biopsy interpretation. ClinicalTrials.gov NCT#01299168.  Kidney rejection initiated by antibodies that were present before transplantation is linked with a better outcome that rejection due to antibodies that arise after transplantation New research provides insights on transplant recipients’ antibody responses against donor kidneys and how the timing of those responses can have important implications. The findings appear in an upcoming issue of the Journal of the American Society of Nephrology (JASN).   2016 American Transplant Congress (ATC) June 11-15, 2016 in Boston, MA Sunday June 12, 2016
1/ Complement-Binding Donor-Specific Anti-HLA Antibodies Are Associated with Severe Kidney Allograft Arteriosclerosis Concurrent Session: Novel Markers of Long Term Kidney Transplant Outcomes (2:30 PM-4:00 PM) Ballroom A - 2:30 pm A. Loupy, D. Viglietti, J. Duong Van Huyen, D. Glotz, C. Legendre, A. Zeevi, C. Lefaucheur. Necker Hospital, Paris, France; Saint-Louis Hospital, Paris, France; University of Pittsburgh Medical Center, Pittsburgh The role of circulating donor-specific anti-HLA antibodies (DSA) in the development of accelerated arteriosclerosis have been recently reported in kidney transplant recipients. This study investigated the characteristics of DSA that are associated with the severity of allograft arteriosclerosis. We enrolled 744 consecutive kidney transplantation performed between January 1, 2004 and January 1, 2010 at Necker Hospital (Paris, France), with systematic assessment of injury phenotype and arteriosclerotic lesions using the vascular fibrous intimal thickening (cv) Banff score on allograft biopsies performed at one year after transplantation. We assessed circulating DSA and their characteristics (specificity, HLA class, mean fluorescence intensity [MFI] and C1q-binding) at six months after transplantation. We identified 281 patients with cv0 score, 213 patients with cv1 score, 189 patients with cv2 score and 61 patients with cv3 score. The distribution of DSA according to cv score was the following: 47/281 (17%) in cv0 patients, 39/213 (18%) in cv1 patients, 63/189 (33%) in cv2 patients and 28/61 (46%) in cv3 patients. Immunodominant DSA (iDSA) MFI level was positively correlated with the severity of arteriosclerosis (Spearman's rho=0.23, p=0.002), with a mean MFI of 3204.0±3725.2 in cv0 patients, 3760±3598 in cv1 patients, 4892±4676 in cv2 patients and 5541±3892 in cv3 patients. C1q-binding DSA prevalence increased with the severity of allograft arteriosclerosis: 8/281 (3%) in cv0 patients, 6/213 (3%) in cv1 patients, 25/189 (13%) in cv2 patients and 9/61 (15%) in cv3 patients (p<0.001). Patients with C1q-binding iDSA had a higher cv score compared with patients with non-C1q-binding DSA (1.7±1.0 versus 1.3±1.1, respectively, p=0.01). The C1q-binding capacity of DSA was associated with increased microvascular inflammation (p<0.001) and C4d deposition in peritubular capillaries or arteries (p<0.001). This study shows a biological gradient between DSA MFI level and the severity of allograft arteriosclerosis. The complement-binding capacity of DSA is associated with an increased severity of arteriosclerosis and complement deposition in allograft. |
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