Biology subjects

Zeevi, A.

Publications and source records attributed to Zeevi, A..

4 recordsLinked to original sources

bioRxiv2025

Liver transplant rejection features memory cell priming, spatially differentiated networks and novel drug targets.

Acute T-cell-mediated transplant rejection, the earliest contributor to immunological graft failure responds variably to T-cell suppression. Early rejection can co-exist with donor-specific antibodies which also shorten graft survival, without affecting graft histology visibly. Here, during early liver transplant rejection, blood leukocytes manifest primed T-cells with heat shock protein (HSP) signaling and transcriptional programs for memory cell expansion. Corresponding biopsies demonstrate upregulated immune synapse and proteasomal genes in T-cell-infiltrated portal and central regions of the liver lobule. With donor-specific antibodies, the intervening intralobular region demonstrates a germinal-center-like allograft response with upregulated CD40, chemokine, T-follicular and complement signaling, which intensifies along the direction of sinusoidal blood flow from portal to central regions. Proteasomal and HSP90 inhibitors suppress donor-specific alloresponses of T- and B-cells in blood samples from patients with early rejection. The molecular injury spectrum of early rejection is complex, spatially differentiated and reveals novel early immunosuppressive strategies to extend graft survival.

immunology↗

bioRxiv2024

Donor HLA DQ reactive B cells clonally expand under chronic immunosuppression and include atypical CD21lowCD27- B cells with high avidity germline B cell receptors.

Long-term allograft survival is limited by humoral-associated chronic allograft rejection, suggesting inadequate constraint of humoral alloimmunity by contemporary immunosuppression. Heterogeneity in alloreactive B cells and the incomplete definition of which B cells participate in chronic rejection in immunosuppressed transplant recipients limits our ability to develop effective therapies. Using a double-fluorochrome single-HLA tetramer approach combined with single-cell in vitro culture, we investigated the B-cell receptor (BCR) repertoire characteristics, avidity, and phenotype of donor HLA-DQ reactive B cells in a transplant recipient with end-stage donor specific antibody (DSA)-associated cardiac allograft vasculopathy while receiving maintenance immunosuppression (tacrolimus, mycophenolate mofetil, prednisone). Donor DQB1*03:02/DQA1*03:01 (DQ8)-reactive IgG+ B cells were enriched for minimally mutated and germline encoded high avidity BCRs (median KD 4.26x10-09) with an atypical, antigen-experienced and proliferative phenotype (CD27-CD21lowCD71+CD11c+/-). These B cells coexisted with a smaller subset of more highly mutated, affinity matured IgG+CD27+ B cells. Circulating donor-reactive B cells and DSA remained detectable after rituximab, contrasting with the marked reduction in DSA after allograft explant and retransplant. Together, these findings define the persistence of germline high-avidity HLA-DQ alloreactive B cells and their co-existence with affinity matured clones that were both driven by the allograft despite conventional immunosuppression.

immunology↗

bioRxiv2022

Enhanced donor antigen presentation by B-cells predicts acute cellular rejection and late outcomes after transplantation.

PurposeEnhanced B-cell presentation of donor alloantigen relative to presentation of HLA-mismatched reference alloantigen is associated with acute cellular rejection (ACR), when expressed as a ratio called the antigen presenting index (API) in an exploratory cohort of liver and intestine transplant (LT, IT) recipients. MethodsTo test clinical performance, we measured the API using the previously described 6-hour assay in 84 LT and 54 IT with median age 3.3 years (0.05-23.96). Recipients experiencing ACR within 60 days after testing were termed rejectors. ResultsWe first confirmed that B-cell uptake and presentation of alloantigen induced and thus reflected the alloresponse of T-helper cells, which were incubated without and with cytochalasin and primaquine to inhibit antigen uptake and presentation, respectively. Transplant recipients included 76 males and 62 females. Rejectors were tested at median 3.6 days before diagnosis. The API was higher among rejectors compared with non-rejectors (2.2 {+/-} 0.2 vs 0.6 {+/-} 0.04, p-value=1.7E-09). In logistic regression and ROC analysis, API [≥] 1.1 achieved sensitivity, specificity, positive and negative predictive values for predicting ACR in 99 training set samples. Corresponding metrics ranged from 80-88% in 32 independent post-transplant samples, and 73-100% in 20 independent pre-transplant samples. In time-to-event analysis, API [≥] 1,1 predicted higher incidence of late DSA after API measurements in LT (p=0.011) and graft loss in IT recipients (p=0.008), compared with recipients with API<1.1, respectively. ConclusionEnhanced donor antigen presentation by circulating B-cells predicts rejection after liver or intestine transplantation as well as higher incidence of DSA and graft loss late after transplantation

immunology↗

bioRxiv2022

The role of dynamic DNA methylation in liver transplant rejection in children

BackgroundTranscriptional regulation of liver transplant (LT) rejection may reveal novel predictive and therapeutic targets. PurposeTo test the role of differential DNA methylation in children with biopsy-proven acute cellular rejection (rejectors, R) after LT. MethodsPaired peripheral blood DNA samples were obtained before and after LT from 17 children, including 4R and 13 non-rejector (NR), and assayed with MethylC capture sequencing (MCC-Seq) approach covering 5 million CpGs in immune-cell specific regulatory elements. Differentially methylated CpGs (DMCs) were identified using generalized linear regression models adjusting for sex and age and merged into differentially methylated regions (DMR) comprising 3 or more DMCs. ResultsContrasting R vs NR, we identified 2238 DMCs in post-LT and 2620 DMCs in pre-LT samples, which clustered in 216 and 282 DMRs respectively. DMCs associated with R were enriched in enhancers and depleted in promoters. The proportion of hypomethylated versus hypermethylated DMRs increased from 22% to 48% (p<0.0001) in pre-LT vs. post-LT DMCs, respectively. The highest-ranked biological processes enriched in post-LT DMCs were antigen processing and presentation via MHC class I, MHC class I complex, and peptide binding (p<7.92E-17), respectively. Top-ranked DMRs mapped to genes which mediate B-cell receptor signaling (ADAP1) or regulate several immune cells (ARRB2) (p<3.75E-08). DMRs in MHC class I genes were enriched for SNPs which bind TFs, affect gene expression and splicing, or alter peptide-binding amino acid sequences. ConclusionsDynamic methylation in distal regulatory regions reveals known transplant-relevant MHC-dependent rejection pathways, and identifies novel loci for future mechanistic evaluations in pediatric transplant subcohorts.

genomics↗