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
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.
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).
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).
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.
We are proud to announce that our team ranked #1 and will be receiving the ESOT 2017StrongerTogether PRO award in Barcelona. You can read all our articles in our website.
We are looking forward to the ESOT congress 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
Circulating donor-specific anti-HLA antibodies are a major factor in premature and accelerated allograft fibrosis.
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.
Antibody-Mediated Rejection Due to Preexisting versus De Novo Donor-Specific Antibodies in Kidney Allograft Recipients
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.
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.
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.
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.
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.
Real Time Central Assessment of Kidney Transplant Indication Biopsies by Microarrays: The INTERCOMEX Study
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.
Conference Organizing Committee
Chair: Kim Solez
Secretary treasurer: Michael Mengel
2017 BANFF-CST Meeting, Scientific Committee
Website : 2017 BANFF-SCT, March 27-31, 2017 | Barcelona, Spain
Conference Organizing Committee - BANFF BOARD
2017 BANFF-CST Meeting, Scientific Committee - Executive Committee
Website : 2017 BANFF-SCT, March 27-31, 2017 | Barcelona, Spain
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).
Molecular Assessment of Microcirculation Injury in Formalin-Fixed Human Cardiac Allograft Biopsies With Antibody-Mediated Rejection.
B. Afzali, E. Chapman, M. Racapé, B. Adam, P. Bruneval, F. Gil, D. Kim, L. Hidalgo, P. Campbell, B. Sis, J. P. Duong Van Huyen, M. Mengel.
Precise diagnosis of antibody-mediated rejection (AMR) in cardiac allograft endomyocardial biopsies (EMBs) remains challenging. This study assessed molecular diagnostics in human EMBs with AMR. A set of 34 endothelial, natural killer cell and inflammatory genes was quantified in 106 formalin-fixed, paraffin-embedded EMBs classified according to 2013 International Society for Heart and Lung Transplantation (ISHLT) criteria. The gene set expression was compared between ISHLT diagnoses and correlated with donor-specific antibody (DSA), endothelial injury by electron microscopy (EM) and prognosis. Findings were validated in an independent set of 57 EMBs. In the training set (n = 106), AMR cases (n = 70) showed higher gene set expression than acute cellular rejection (ACR; n = 21, p < 0.001) and controls (n = 15, p < 0.0001). Anti-HLA DSA positivity was associated with higher gene set expression (p = 0.01). Endothelial injury by electron microscopy strongly correlated with gene set expression, specifically in AMR cases (r = 0.62, p = 0.002). Receiver operating characteristic curve analysis for diagnosing AMR showed greater accuracy with gene set expression (area under the curve [AUC] = 79.88) than with DSA (AUC = 70.47) and C4d (AUC = 70.71). In AMR patients (n = 17) with sequential biopsies, increasing gene set expression was associated with inferior prognosis (p = 0.034). These findings were confirmed in the validation set. In conclusion, biopsy-based molecular assessment of antibody-mediated microcirculation injury has the potential to improve diagnosis of AMR in human cardiac transplants.
Value of Donor-Specific Anti-HLA Antibody Monitoring and Characterization for Risk Stratification of Kidney Allograft Loss
The diagnosis system for allograft loss lacks accurate individual risk stratification on the basis of donor-specific anti-HLA antibody (anti-HLA DSA) characterization. We investigated whether systematic monitoring of DSA with extensive characterization increases performance in predicting kidney allograft loss. This prospective study included 851 kidney recipients transplanted between 2008 and 2010 who were systematically screened for DSA at transplant, 1 and 2 years post-transplant, and the time of post-transplant clinical events. We assessed DSA characteristics and performed systematic allograft biopsies at the time of post-transplant serum evaluation. At transplant, 110 (12.9%) patients had DSAs; post-transplant screening identified 186 (21.9%) DSA-positive patients. Post-transplant DSA monitoring improved the prediction of allograft loss when added to a model that included traditional determinants of allograft loss (increase in c statistic from 0.67; 95% confidence interval [95% CI], 0.62 to 0.73 to 0.72; 95% CI, 0.67 to 0.77). Addition of DSA IgG3 positivity or C1q binding capacity increased discrimination performance of the traditional model at transplant and post-transplant. Compared with DSA mean fluorescence intensity, DSA IgG3 positivity and C1q binding capacity adequately reclassified patients at lower or higher risk for allograft loss at transplant (category-free net reclassification index, 1.30; 95% CI, 0.94 to 1.67; P<0.001 and 0.93; 95% CI, 0.49 to 1.36; P<0.001, respectively) and post-transplant (category-free net reclassification index, 1.33; 95% CI, 1.03 to 1.62; P<0.001 and 0.95; 95% CI, 0.62 to 1.28; P<0.001, respectively). Thus, pre- and post-transplant DSA monitoring and characterization may improve individual risk stratification for kidney allograft loss.
The purpose of the present review is to describe how we improve the model for risk stratification of transplant outcomes in kidney transplantation by incorporating the novel insights of donor-specific anti-HLA antibody (DSA) characteristics. The detection of anti-HLA DSA is widely used for the assessment of pre- and posttransplant risks of rejection and allograft loss; however, not all anti-HLA DSA carry the same risk for transplant outcomes. These antibodies have been shown to cause a wide spectrum of effects on allografts, ranging from the absence of injury to indolent or full-blown acute antibody-mediated rejection. Consequently, the presence of circulating anti-HLA DSA does not provide a sufficient level of accuracy for the risk stratification of allograft outcomes. Enhancing the predictive performance of anti-HLA DSA is currently one of the most pressing unmet needs for facilitating individualized treatment choices that may improve outcomes. Recent advancements in the assessment of anti-HLA DSA properties, including their strength, complement-binding capacity, and IgG subclass composition, significantly improved the risk stratification model to predict allograft injury and failure. Although risk stratification based on anti-HLA DSA properties appears promising, further specific studies that address immunological risk stratification in large and unselected populations are required to define the benefits and cost-effectiveness of such comprehensive assessment prior to clinical implementation.
Gene Expression Profiling for the Identification and Classification of Antibody-Mediated Heart Rejection
Antibody-mediated rejection (AMR) contributes to heart allograft loss. However, an important knowledge gap remains in terms of the pathophysiology of AMR and how detection of immune activity, injury degree, and stage could be improved by intragraft gene expression profiling.
We prospectively monitored 617 heart transplant recipients referred from 4 French transplant centers (January 1, 2006-January 1, 2011) for AMR. We compared patients with AMR (n=55) with a matched control group of 55 patients without AMR. We characterized all patients using histopathology (ISHLT [International Society for Heart and Lung Transplantation] 2013 grades), immunostaining, and circulating anti-HLA donor-specific antibodies at the time of biopsy, together with systematic gene expression assessments of the allograft tissue, using microarrays. Effector cells were evaluated with in vitro human cell cultures. We studied a validation cohort of 98 heart recipients transplanted in Edmonton, AB, Canada, including 27 cases of AMR and 71 controls.
A total of 240 heart transplant endomyocardial biopsies were assessed. AMR showed a distinct pattern of injury characterized by endothelial activation with microcirculatory inflammation by monocytes/macrophages and natural killer (NK) cells. We also observed selective changes in endothelial/angiogenesis and NK cell transcripts, including CD16A signaling and interferon-γ-inducible genes. The AMR-selective gene sets accurately discriminated patients with AMR from those without and included NK transcripts (area under the curve=0.87), endothelial activation transcripts (area under the curve=0.80), macrophage transcripts (area under the curve=0.86), and interferon-γ transcripts (area under the curve=0.84; P<0.0001 for all comparisons). These 4 gene sets showed increased expression with increasing pathological AMR (pAMR) International Society for Heart and Lung Transplantation grade (P<0.001) and association with donor-specific antibody levels. The unsupervised principal components analysis demonstrated a high proportion of molecularly inactive pAMR1(I+), and there was significant molecular overlap between pAMR1(H+) and full-blown pAMR2/3 cases. Endothelial activation transcripts, interferon-γ, and NK transcripts showed association with chronic allograft vasculopathy. The molecular architecture and selective AMR transcripts, together with gene set discrimination capacity for AMR identified in the discovery set, were reproduced in the validation cohort.
Tissue-based measurements of specific pathogenesis-based transcripts reflecting NK burden, endothelial activation, macrophage burden, and interferon-γ effects accurately classify AMR and correlate with degree of injury and disease activity. This study illustrates the clinical potential of a tissue-based analysis of gene transcripts to refine diagnosis of heart transplant rejection.
On December 14th, 2016, Phil Halloran received the award of Doctor Honoris Causa in Paris.
The movie tells the story of renal transplantation and its most famous contributors.
The Banff 2015 Kidney Meeting Report: Current Challenges in Rejection Classification and Prospects for Adopting Molecular Pathology.
A. Loupy, M. Haas, K. Solez, L. Racusen, D. Glotz, D. Seron, B. J. Nankivell, R. B. Colvin, M. Afrouzian, E. Akalin, N. Alachkar, S. Bagnasco, J. U. Becker, L. Cornell, C. Drachenberg, D. Dragun, H. de Kort, I. W. Gibson, E. S. Kraus C. Lefaucheur, C. Legendre, H. Liapis, T. Muthukumar, V. Nickeleit, B. Orandi, W. Park, M. Rabant, P. Randhawa, E. F. Reed, C. Roufosse, S. V. Seshan, B. Sis, H. K. Singh, C. Schinstock, A. Tambur, A. Zeevi, M. Mengel.
The XIII Banff meeting, held in conjunction the Canadian Society of Transplantation in Vancouver, Canada, reviewed the clinical impact of updates of C4d-negative antibody-mediated rejection (ABMR) from the 2013 meeting, reports from active Banff Working Groups, the relationships of donor-specific antibody tests (anti-HLA and non-HLA) with transplant histopathology, and questions of molecular transplant diagnostics. The use of transcriptome gene sets, their resultant diagnostic classifiers, or common key genes to supplement the diagnosis and classification of rejection requires further consensus agreement and validation in biopsies. Newly introduced concepts include the i-IFTA score, comprising inflammation within areas of fibrosis and atrophy and acceptance of transplant arteriolopathy within the descriptions of chronic active T cell-mediated rejection (TCMR) or chronic ABMR. The pattern of mixed TCMR and ABMR was increasingly recognized. This report also includes improved definitions of TCMR and ABMR in pancreas transplants with specification of vascular lesions and prospects for defining a vascularized composite allograft rejection classification. The goal of the Banff process is ongoing integration of advances in histologic, serologic, and molecular diagnostic techniques to produce a consensus-based reporting system that offers precise composite scores, accurate routine diagnostics, and applicability to next-generation clinical trials.
Figure 1: Molecular lesions and their corresponding histologic lesions in T cell–mediated rejection and antibody‐mediated rejection in kidney allografts. cg, glomerular double contours; cv, vascular fibrous intimal thickening; i, inflammation; ptc, peritubular capillaritis; ti, total inflammation; v, intimal arteritis.
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.
M. Racapé, A. Loupy, J. Reeve, J. Venner, R. Guillemain, L. Hidalgo, C. Lefaucheur, X. Jouven, P. Bruneval, J. Duong Van Huyen, P. Halloran.
The XIIIth Banff Conference on Allograft Pathology: The Banff 2015 Heart Meeting Report: Improving Antibody-Mediated Rejection Diagnostics: Strengths, Unmet Needs, and Future Directions.
Bruneval P, Angelini A, Miller D, Potena L, Loupy A, Zeevi A, Reed EF, Dragun D, Reinsmoen N, Smith RN, West L, Tebutt S, Thum T, Haas M, Mengel M, Revelo P, Fedrigo M, Duong Van Huyen JP, Berry GJ.
The 13th Banff Conference on Allograft Pathology was held in Vancouver, British Columbia, Canada from October 5 to 10, 2015. The cardiac session was devoted to current diagnostic issues in heart transplantation with a focus on antibody-mediated rejection (AMR) and small vessel arteriopathy. Specific topics included the strengths and limitations of the current rejection grading system, the central role of microvascular injury in AMR and approaches to semiquantitative assessment of histopathologic and immunophenotypic indicators, the role of AMR in the development of cardiac allograft vasculopathy, the important role of serologic antibody detection in the management of transplant recipients, and the potential application of new molecular approaches to the elucidation of the pathophysiology of AMR and potential for improving the current diagnostic system. Herein we summarize the key points from the presentations, the comprehensive, open and wide-ranging multidisciplinary discussion that was generated, and considerations for future endeavors.
Figure 3: Spectrum of cardiac allograft vasculopathy (from epicardial arteries to myocardial capillaries). (A) Allograft epicardial coronary artery showing intimal and adventitial inflammation (hematoxylin and eosin [H&E], ×100). (B) Allograft epicardial coronary artery showing intimal fibrosis with shallow fibrin thrombus at the luminal aspect and some entrapped fibrin deeper in the intimal wall (arrows) (H&E, ×20). (C) Allograft epicardial coronary artery with less intimal thickening but dramatic adventitial lymphoid aggregate (asterisk) (H&E, ×20). (D) Allograft epicardial coronary artery showing advanced narrowing with a slit‐like lumen; there is very little outward remodeling of the vessel wall (H&E, ×40). (E) Allograft endomyocardial biopsy photomicrograph after computer‐assisted image analysis for capillary density. This case showed reduced capillaries (CD34 stain, ×200) (MVD, microvascular density). (F) Allograft endomyocardial biopsy photomicrograph after computer‐assisted image analysis for capillary density. This case showed preserved capillary density (CD34 stain, ×200). (G) and (H) Electron photomicrographs of allograft myocardium showing an interstitial capillary with basement membrane multilayering (arrows) (original ×4000 and ×10 000).
Conference Organizing Committee
2015 BAnff/CST Meeting, Organizing Corporation (MOC)
Alexandre Loupy, chair
Cinthia Beskox Drachenberg
W. Dean Wallace
Linda C cendales
2015 BANFF/CST, October 5-10, 2016 | Vancouver, BC
Kidney allograft rejection can occur in clinically stable patients, but long-term significance is unknown. We determined whether early recognition of subclinical rejection has long-term consequences for kidney allograft survival in an observational prospective cohort study of 1307 consecutive nonselected patients who underwent ABO-compatible, complement-dependent cytotoxicity-negative crossmatch kidney transplantation in Paris (2000-2010). Participants underwent prospective screening biopsies at 1 year post-transplant, with concurrent evaluations of graft complement deposition and circulating anti-HLA antibodies. The main analysis included 1001 patients. Three distinct groups of patients were identified at the 1-year screening: 727 (73%) patients without rejection, 132 (13%) patients with subclinical T cell-mediated rejection (TCMR), and 142 (14%) patients with subclinical antibody-mediated rejection (ABMR). Patients with subclinical ABMR had the poorest graft survival at 8 years post-transplant (56%) compared with subclinical TCMR (88%) and nonrejection (90%) groups (P<0.001). In a multivariate Cox model, subclinical ABMR at 1 year was independently associated with a 3.5-fold increase in graft loss (95% confidence interval, 2.1 to 5.7) along with eGFR and proteinuria (P<0.001). Subclinical ABMR was associated with more rapid progression to transplant glomerulopathy. Of patients with subclinical TCMR at 1 year, only those who further developed de novo donor-specific antibodies and transplant glomerulopathy showed higher risk of graft loss compared with patients without rejection. Our findings suggest that subclinical TCMR and subclinical ABMR have distinct effects on long-term graft loss. Subclinical ABMR detected at the 1-year screening biopsy carries a prognostic value independent of initial donor-specific antibody status, previous immunologic events, current eGFR, and proteinuria.
Rejection is one of the major causes of late cardiac allograft failure and at present can only be diagnosed by invasive endomyocardial biopsies. We sought to determine whether microRNA profiling could serve as a non-invasive biomarker of cardiac allograft rejection.
We included 113 heart transplant recipients from four referral French institutions (test cohort, n = 60, validation cohort, n = 53). In the test cohort, we compared patients with acute biopsy-proven allograft rejection (n = 30) to matched control patients without rejection (n = 30), by assessing microRNAs expression in the heart allograft tissue and patients concomitant serum using RNA extraction and qPCR analysis. Fourteen miRNAs were selected on the basis of their implication in allograft rejection, endothelial activation, and inflammation and tissue specificity.
We identified seven miRNAs that were differentially expressed between normal and rejecting heart allografts: miR-10a, miR-21, miR-31, miR-92a, miR-142-3p miR-155, and miR-451 (P < 0.0001 for all comparisons). Four out of seven miRNAs also showed differential serological expression (miR-10a, miR-31, miR-92a, and miR-155) with strong correlation with their tissular expression. The receiver-operating characteristic analysis showed that these four circulating miRNAs strongly discriminated patients with allograft rejection from patients without rejection: miR-10a (AUC = 0.975), miR-31 (AUC = 0.932), miR-92a (AUC = 0.989), and miR-155 (AUC = 0.998, P < 0.0001 for all comparisons). We confirmed in the external validation set that these four miRNAs highly discriminated patients with rejection from those without. The discrimination capability of the four miRNAs remained significant when stratified by rejection diagnosis (T-cell-mediated rejection or antibody-mediated rejection) and time post-transplant.
This study demonstrates that a differential expression of miRNA occurs in rejecting allograft patients, not only at the tissue level but also in the serum, suggesting their potential relevance as non-invasive biomarkers in heart transplant rejection.
Molecular Microscope Strategy to Improve Risk Stratification in Early Antibody-Mediated Kidney Allograft Rejection
Antibody-mediated rejection (ABMR) is the leading cause of kidney allograft loss. We investigated whether the addition of gene expression measurements to conventional methods could serve as a molecular microscope to identify kidneys with ABMR that are at high risk for failure. We studied 939 consecutive kidney recipients at Necker Hospital (2004–2010; principal cohort) and 321 kidney recipients at Saint LouisHospital (2006–2010; validation cohort) and assessed patients with ABMR in the first 1 year post-transplant. In addition to conventional features, we assessed microarray-based gene expression in transplant biopsy specimens using relevant molecular measurements: the ABMRMolecular
Score and endothelial donor-specific antibody-selective transcript set. The main outcomes were kidney transplant loss and progression to chronic transplant injury. We identified 74 patientswith ABMR in the principal cohort and 54 patients with ABMR in the validation cohort. Conventional features independently associated with failure were donor age and humoral histologic score (g+ptc+v+cg+C4d). Adjusting for conventional features, ABMR Molecular Score (hazard ratio [HR], 2.22; 95% confidence interval [95% CI], 1.37 to 3.58; P=0.001) and endothelial donor-specific antibody-selective transcripts (HR, 3.02; 95% CI, 1.00 to 9.16; P,0.05) independently associated with an increased risk of graft loss. The results were replicated in the independent validation group. Adding a gene expression assessment to a traditional risk model improved the stratification of patients at risk for graft failure (continuous net reclassification improvement, 1.01; 95% CI, 0.57 to 1.46; P,0.001; integrated discrimination improvement, 0.16; P,0.001). Compared with conventional assessment, the addition of gene expression measurement in kidney transplants with ABMR improves stratification of patients at high risk for graft loss.
AbstractAnti-HLA antibodies hamper successful transplantation, and activation of the complement cascade is involved in antibody-mediated rejection. We investigated whether the complement-binding capacity of anti-HLA antibodies plays a role in kidney-allograft failure.
We enrolled patients who received kidney allografts at two transplantation centers in Paris between January 1, 2005, and January 1, 2011, in a population-based study.
Patients were screened for the presence of circulating donor-specific anti-HLA antibodies and their complement-binding capacity. Graft injury phenotype and the time to kidney-allograft loss were assessed.
The primary analysis included 1016 patients. Patients with complement-binding donor-specific anti-HLA antibodies after transplantation had the lowest 5-year rate of graft survival (54%), as compared with patients with non–complement-binding donor-specific anti-HLA antibodies (93%) and patients without donor-specific anti-HLA antibodies (94%) (P<0.001 for both comparisons). The presence of complement-binding donor-specific anti-HLA antibodies after transplantation was associated with a risk of graft loss that was more than quadrupled (hazard ratio, 4.78; 95% confidence interval [CI], 2.69 to 8.49) when adjusted for clinical, functional, histologic, and immunologic factors. These antibodies were also associated with an increased rate of antibody-mediated rejection, a more severe graft injury phenotype with more extensive microvascular inflammation, and increased deposition of complement fraction C4d within graft capillaries. Adding complement-binding donor specific anti-HLA antibodies to a traditional risk model improved the stratification of patients at risk for graft failure (continuous net reclassification improvement, 0.75; 95% CI, 0.54 to 0.97).
Assessment of the complement-binding capacity of donor-specific anti-HLA antibodies appears to be useful in identifying patients at high risk for kidney-allograft loss.
Paris Transplant Group
Our global aim is to accelerate the translation of immunological and gene expression discoveries into the clinical field by filling the gap between basic science and applied biomedical researches.