Enhanced B Cell Alloantigen Presentation and Its Epigenetic Dysregulation in Liver Transplant Rejection

Abstract

T-cell suppression prevents acute cellular rejection but causes life-threatening infections and malignancies. Previously, liver transplant (LTx) rejection in children was associated with the SNP rs9296068 upstream of the HLA-DOA gene. HLA-DOA inhibits B-cell presentation of antigen, a potentially novel anti-rejection drug target. Using archived samples from 122 Caucasian pediatric LTx (including 77 described previously), we now confirm the association between rs9296068 and LTx rejection (p=0.001, OR=2.55). Next-generation sequencing reveals that the putative transcription-factor-(CTCF)-binding SNP locus rs2395304, in linkage disequilibrium with rs9296068 (D’=0.578, r2=0.4), also associates with LTx rejection (p=0.008, OR=2.34). Further, LTx rejection is associated with enhanced B-cell presentation of donor antigen relative to HLA-non-identical antigen in a novel cell-based assay, and with a downregulated HLA-DOA gene in a subset of these children. In lymphoblastoid B-(Raji) cells, rs2395304 co-immunoprecipitates with CTCF, and CTCF knockdown with morpholino antisense oligonucleotides enhances alloantigen presentation and downregulates the HLA-DOA gene, reproducing observations made with HLA-DOA knockdown and clinical rejection. Alloantigen presentation is suppressed by inhibitors of methylation and histone deacetylation, reproducing observations made during resolution of rejection. Enhanced donor antigen presentation by B-cells and its epigenetic dysregulation via the HLA-DOA gene represent novel opportunities for surveillance and treatment of transplant rejection.

The Immunological Basis of Liver Allograft Rejection

“…Potential mechanisms include the activation of T-cells by B-cells via costimulatory pathways and cytokine release and promoting T-cell differentiation into memory T-cells ( 60 ). B-cell presentation of donor antigen is enhanced during liver allograft rejection and may provide a novel target for immunosuppression ( 61 ). The main role of B-cells is however, the production of antibody which is of key importance for antibody mediated rejection.…”

Operational tolerance in intestinal transplantation

“…Functional T cell assays revealed that he was otherwise immunocompetent with normal antiviral CD3 + T cell reactivity against CMV antigen pp65 and Epstein‐Barr virus (EBV) lysate (Figure 2A,B). Functional assessment of alloreactivity and antigen presentation with mixed lymphocyte culture and antigen presentation assays, 5‐7 demonstrated that he had evidence of donor‐specific hyporesponsiveness at both a T cell and antigen presentation level. Specifically, he showed a hyporesponsive CD154‐expression response of his CD8 + CD45RO + memory T cells against donor‐HLA matched stimulation when compared to stimulation with HLA mismatched third‐party (Figure 3A).…”

“…The P value for the Poisson test between background and donor‐induced CD154 + T‐cytotoxic memory cells was .0002 and the P value for the Poisson test between background and third‐party reference was 2.20E‐16. B,C, Flow cytometry scatterplots show frequencies of B cells (B) and monocytes (C) that present fluorochrome‐labeled antigenic lysate prepared from donor and reference PBL, as described previously referenced 6,7 . The antigen‐presenting index (API) is the ratio of B cell or monocyte frequencies that present donor‐ and reference antigen.…”

Two histologically colorectal carcinomas subsets from the serrated pathway show different methylome signatures and diagnostic biomarkers

“…Very few articles correlated HLA-DOA with immune response features. Wang et al reported that hypomethylation of CpGs in 6p21.3, where HLA-DOA is located, was associated with increased CD8 T cell tumour infiltration in serous ovarian cancer [ 26 ] whereas Ningappa et al and Sindhi et al demonstrated that HLA-DOA inhibits B cell presentation of antigen and consequently these authors proposed a potentially novel antirejection drug target [ 27 , 28 ]. Our results are in line with these latter works; as transcription of major histocompatibility genes is silenced by DNA methylation [ 29 ] of upstream promoters, it would not be surprising that higher HLA-DOA methylation in hmMSI-H might have an effect on enhancing antigen presentation by B cells and generate a more prominent immune response.…”