Project description:CD163 macrophages, which can be identified in different tissues of individuals such as the colon and tumor tissues, possessed markedly immunosuppressive functions on immune cells, especially effective cells such as CD8 cells. However, the mechanism(s) by which CD163 macrophages inhibit immune responses remains to be illusive. Using single cell-sequence techniques, we identified CD163+ macrophage subset in the colon tissues. Meanwhile, we also characterized CD163+ macrophage associated immune cell populations and subpopulations in mouse colon tissues. Deletion of CD163+ macrophage subset could markedly increase the proportions of CD8 and NK cells. Mechanistically, CD163+ macrophage subpopulations can inhibit the proliferation of CD8 and NK cells through inhibitory molecules CD94/NKG2a (KLRD1/KLRC1 in mice) and their ligand HLA-E /H2-T23 (Human/mice) on the surface of CD163+ macrophages. Importantly, CD163 in macrophages could promote the expression of HLA-E/H2-T23 expression through inducing the expression of signal peptide peptidase (SPP), offering a target for immunotherapy in CD8 and NK cells associated immunosuppressive diseases such as tumor. Taken together, we demonstrate that CD163+macrophage subpopulation plays a critical role in suppressing CD8 and NK cells through CD163 mediated HLA-E/H2-T23.
Project description:Analysis of the peptide repertoires eluted from different HLA-DP molecules expressed in HeLa cells co-expressing Invariant chain either with or without HLA-DM as components of the HLA class II processing machinery. Divergence of the immunopeptidomes and the impact of HLA-DM were investigated in relation to the capacity of HLA-DP molecules to elicit alloreactive T-cell responses.
Project description:In the context of HLA-DP-mismatched allogeneic stem cell transplantation, mismatched HLA-DP alleles can provoke profound allo-HLA-DP-specific immune responses from the donor T-cell repertoire leading to graft-versus-leukemia effect and/or graft-versus-host disease in the patient. The magnitude of allo-HLA-DP-specific immune responses has been shown to depend on the specific HLA-DP disparity between donor and patient and the immunogenicity of the mismatched HLA-DP allele(s). HLA-DP peptidome clustering (DPC) was developed to classify the HLA-DP molecules based on similarities and differences in their peptide-binding motifs. To investigate a possible categorization of HLA-DP molecules based on overlap of presented peptides, we identified and compared the peptidomes of the thirteen most frequently expressed HLA-DP molecules. Our categorization based on shared peptides was in line with the DPC classification. We found that the HLA-DP molecules within the previously defined groups DPC-1 or DPC-3 shared the largest numbers of presented peptides. However, the HLA-DP molecules in DPC-2 segregated into two subgroups based on the overlap in presented peptides. Besides overlap in presented peptides within the DPC groups, a substantial number of peptides was also found to be shared between HLA-DP molecules from different DPC groups, especially for groups DPC-1 and -2. The functional relevance of these findings was illustrated by demonstration of cross-reactivity of allo-HLA-DP-reactive T-cell clones not only against HLA-DP molecules within one DPC group, but also across different DPC groups. The promiscuity of peptides presented in various HLA-DP molecules and the cross-reactivity against different HLA-DP molecules demonstrate that these molecules cannot be strictly categorized in immunogenicity groups.
Project description:Nasopharyngeal carcinoma (NPC) is prevalent in East and Southeast Asia, with genetic factors playing a significant role in its occurrence. The HLA gene region on chromosome 6 is linked to NPC susceptibility, but the mechanisms remain unclear. Epstein-Barr virus (EBV) infection is a well-established cause, with 95% of NPC patients being EBV-positive. Three key variations in the EBV genome (162215_C, 162476_C, 163364_T) in the BALF2 gene are strongly associated with NPC risk. This study finds that the high-risk BALF2 variant (BALF2-HR) upregulates HLA class II molecules, such as HLA-DP, which interacts with LAG-3 on CD8⁺ T cells, inhibiting cytokine secretion and promoting T cell exhaustion, leading to immune evasion and reduced anti-PD-1 efficacy. BALF2-HR also enhances HLA-DP transcription by binding to KPNA2 and facilitating CIITA nuclear translocation. Conjunctive immunotherapy with anti-LAG-3 and anti-PD-1 antibodies significantly improves NPC treatment. This work introduces a new therapeutic strategy for NPC and insights into infection-associated cancers.
Project description:The development of neutralizing antibodies (inhibitors) against coagulation factor VIII (FVIII) poses a major challenge in hemophilia A (HA) treatment. The formation of FVIII inhibitors is a CD4+ T-cell-dependent mechanism which includes anti- gen presenting cells (APC), B- and T-helper lymphocytes. APC present FVIII-derived peptides on major histocompatibility complex class II (MHC-II) to CD4+ T cells. We previously established a mass spectrometry-based approach to delineate the FVIII repertoire presented on HLA-DR and HLA-DQ. In this study, specific attention was directed towards the identification of FVIII peptides presented on HLA-DP. A data-set of naturally processed FVIII peptides was generated by incubating human FVIII with immature monocyte-derived dendritic cells (moDC) from HLA-typed healthy donors. Using this method, we iden- tified 176 to 1,352 different HLA-DP presented peptides per donor, including 26 different FVIII-derived peptides. The most frequently presented peptides derived from the A3 and C2 domains of FVIII. Comparison of the FVIII repertoire presented on HLA-DP with that presented on HLA-DR revealed considerable overlap but also suggested preferential presentation of specific peptides on either HLA-DR or HLA-DP. Fourteen FVIII peptides presented on HLA-DP were synthesized and evalu- ated for their binding ability to the commonly expressed HLA-DP4 molecule which is highly prevalent in the Caucasian population. Peptide binding studies showed that 7 of 14 peptides competed with a reference peptide to HLA-DP4. Interest- ingly, an A3 domain-derived peptide bound with high affinity to HLA-DP4, positioning this peptide as a prime candidate for the development of novel peptide-based tolerogenic strategies for FVIII inhibitors.
Project description:A high-throughput mass spectrometry analysis was used to identify more than 16,000 cell peptides bound to several HLA-DR and -DP class II molecules isolated from large amounts of two human cell lines (HOM-2 and JY).
Project description:Despite great success in certain cancers, immunotherapy made little progress in treating immune “cold” tumors, like prostate cancer, largely attributed to an immunesuppressive tumor microenvironment with elusive mechanisms. Here, we report in prostate cancer cells a positive feed-back loop driven by PSAT1 that could be targeted to render effective cytotherapy by NK cells. In the loop, PSAT1 increases YBX1 phosphorylation by MARK2, promoting its nuclear translocation to upregulate PSAT1 transcription. Meanwhile, YBX1 also promotes HLA-E transcription, a ligand for inhibitory KIRs inactivating NK cells. As a result, the PSAT1 loop serves as a buff to sustain YBX1 and HLA-E expression, suppressing NK killing of prostate cancer cells.