4Three Pathways to Antibody-Mediated Injury Antibody AloneComplementMediatedCell Mediated (FcR)Farkash and Colvin, Nat Rev Nephrol 8:255, 2012
5Role of C4d in antibody-mediated rejection Classical complement pathway activation:Antibody + AntigenC1C C4a + C4bMannose binding lectin/MASP1Tx 1377C4dbinds covalently to local siteHelmut Feucht Clin Exp Immunol 86:464, 1991
6Detection of C4d is crucial for diagnosing antibody mediated rejection
7Microcirculation inflammation in AMR KidneyHeartCD68CD3
8Phenotype of glomerulits CD15 – early AMRCD68 – late AMR
9Diagnosis of AMRMengel M et al. Transpl Int Jun;25(6):611-22
10Follow up of C4d positive biopsies and the development of TX-Glomerulopathy Significant more often associated with Transplant Glomerulopathy (53% vs. 14%)Significant more often associated with Transplant Capillaropathy (71% vs. 13%)Significantly associated with progression of Transplant Glomerulopathy in follow-up biopsy (82% vs. 27%, median after 23 months)Regele et al.
13antibody-mediated injury and microcirculation inflammation glomerulitisglomerulopathy
14Sequential development of CHR in non-human primates No CHR Stage I Stage II Stage III Stage IVDays post-transplantSmith et al (Boston) AJT 8:1662, 2008
15C4d versus microcirculation inflammation in biopsies prior to AMR treatment (1996-2001) Verghese et al. Clin. Transplant 2013 in press
16Biopsies for late graft dysfunction DeKAF StudyBiopsies for late graft dysfunctionC4d-DSA-C4d-DSA+C4d+DSA-C4d+DSA+Months post-bxN=173Gaston et al Transplant 90:68,20101616
17Graft SurvivalBanff lesionsunsupervised Principal Component Analysis
18Limited specificity of microcirculation inflammation Fahim et al. Am J Transplant. 2007 Feb;7(2):% cases with capillaritisGibson et al. Am J Transplant Apr;8(4):
19The association of TG (D) (n=44) with antibody (A), PTCBMML (B), and C4d (C). TG phenotype*ABCDn (%)“ABCD”+10 (27)“ABD”-12 (32)“ACD”2 (5)“AD”1 (3)“BCD”“BD”9 (24)“CD”“D”73% of Tg cases show some signs of humoral rejectionSis et al. AJT 2007; 7:
20Loupy et al: Subclinical progressive microcirculation injury in presensitized patients, despite C4d negativity20
21Potential causes for C4d negativity Complement activationComplement dependent cell injuryEndothelial activationRecruitment and activation of leukocytesC4d+ ABMRIs C4d deposited in low amounts(Thus not detectable by current methods)Treatment effects??C4d negative ABMR?Do HLA antibodies in a complement-independent way causeEC activation andsubsequent inflammation andFc receptor mediated graft injury?
22Three Pathways to Antibody-Mediated Injury Antibody AloneComplementMediatedCell Mediated (FcR)Farkash and Colvin, Nat Rev Nephrol 8:255, 2012
23endothelial genes are increased in AMR Also not in our strictdefinition of ENDAT list,but increased in ABMR:CDH13Duffy blood groupSOX7THBDMALLWelch t testFDR 0.05Red arrows indicate genes that are known to beinvolved in endothelial cell activationSis et al. AJT 2009;9:
24Endothelial Transcripts Peritubular capillaritis Endothelial Cell-Associated Transcripts correlate with pathologic features of AMR (in 173 biopsies)Endothelial TranscriptsCorrelation coefficientpC4d deposition.376p<0.001Peritubular capillaritis.2520.002PTCBMML.2660.004g.2480.001i.358t.135NSv.092cg.261mm.1730.02ci.330ct.286cv.014ah-.050Sis et al. AJT 2009;9:
25C4d is negative in 60% of chronic active ABMR biopsies with no En=21with ETransplantGlomerulopathyscore ( cg, mean + 95% CI)n=81p=0.01p=0.53Cumulative SurvivalPost-biopsy time (months)p=0.001or60%C4d negativen=81Incidence of transplant glomerulopathy (*%)No Abn=30Ab with no En=21Ab with EC4d+ Transplant GlomerulopathyC4d Negative Transplant Glomerulopathy6.7%19%43%Sis et al. Am J Transplant Oct;9(10):
26Transcripts selectively associated with DSA: Endothelial and NK cell transcripts Hidalgo et al. AJT 2010; 10: 1812–1822
27NK cells and macrophages in antibody mediated peritubular capillaritis C4d+ ABMRC4d- ABMRTCMRMean number of positive cellsin five peritubular capillariesCD CD CD3+C.CD56D.CD68E.CD3Hidalgo et al. AJT 2010; 10: 1812–1822
28Role of complement and NK cells in antibody mediated rejection AMRAMR + anti NKNK cell stainAkiyoshi and Colvin at al. Human Immunology Volume 73, IssueHirohashi and Colvin et al. Am J Transplant Feb;12(2):
29A molecular classifier for diagnosing AMR Classifier score correlates with:Pathology (ptc, g, cg, I, cv, ah, ct, ci)Consensus amongst pathologistsPresence of DSAoutcomeSellares et al. Am J Transplant Apr;13(4):
30Sellares et al. Am J Transplant. 2013 Apr;13(4):971-83.
32SummaryDonor-specific antibody acting on the allograft is associated with endothelial cell and local complement activation [ in most cases]DSA acting on the allograft is associated with microcirculation inflammation as the morphological correlate [notion: the antigen is expressed in the microcirculation]DSA acting on the allograft is associated with increased expression of inflammation (T cells, macrophages, g-interferon), endothelial, and NK cell associated transcripts as the molecular correlate
34ObjectiveTo review the current knowledge of mechanisms, diagnostics and clinical management of patients with antibody-mediated rejection.Since the vast majority of experience in this area has been accumulated in renal transplant patients, this group of patients will be the main focus of the presentation, but relevant lessons applicable to other types of organ transplants will be discussed as well.
35Intragraft gene expression in positive crossmatch kidney allografts Class – Comparisons:A and B: no significant differences in gene expressionC and D: over-expression of inflammatory transcripts (T cells, macrophages, g-interferon) in XM+ biopsiesBlack error indicate class comparisons of gene expression.All cases are living donors.Dean et al. Am J Transplant 2012; 12:
36Limited specificity of capillaritis % cases with capillaritisGibson et al. Am J Transplant Apr;8(4):