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Cell Chemical Biology Oct 2023Targeting transcription replication conflicts, a major source of endogenous DNA double-stranded breaks and genomic instability could have important anticancer...
Targeting transcription replication conflicts, a major source of endogenous DNA double-stranded breaks and genomic instability could have important anticancer therapeutic implications. Proliferating cell nuclear antigen (PCNA) is critical to DNA replication and repair processes. Through a rational drug design approach, we identified a small molecule PCNA inhibitor, AOH1996, which selectively kills cancer cells. AOH1996 enhances the interaction between PCNA and the largest subunit of RNA polymerase II, RPB1, and dissociates PCNA from actively transcribed chromatin regions, while inducing DNA double-stranded breaks in a transcription-dependent manner. Attenuation of RPB1 interaction with PCNA, by a point mutation in RPB1's PCNA-binding region, confers resistance to AOH1996. Orally administrable and metabolically stable, AOH1996 suppresses tumor growth as a monotherapy or as a combination treatment but causes no discernable side effects. Inhibitors of transcription replication conflict resolution may provide a new and unique therapeutic avenue for exploiting this cancer-selective vulnerability.
Topics: Humans; Proliferating Cell Nuclear Antigen; Chromatin; Protein Binding; Neoplasms; DNA; DNA Replication
PubMed: 37531956
DOI: 10.1016/j.chembiol.2023.07.001 -
Nature Reviews. Immunology Jul 2023IgGs are essential soluble components of the adaptive immune response that evolved to protect the body from infection. Compared with other immunoglobulins, the role of... (Review)
Review
IgGs are essential soluble components of the adaptive immune response that evolved to protect the body from infection. Compared with other immunoglobulins, the role of IgGs is distinguished and enhanced by their high circulating levels, long half-life and ability to transfer from mother to offspring, properties that are conferred by interactions with neonatal Fc receptor (FcRn). FcRn binds to the Fc portion of IgGs in a pH-dependent manner and protects them from intracellular degradation. It also allows their transport across polarized cells that separate tissue compartments, such as the endothelium and epithelium. Further, it is becoming apparent that FcRn functions to potentiate cellular immune responses when IgGs, bound to their antigens, form IgG immune complexes. Besides the protective role of IgG, IgG autoantibodies are associated with numerous pathological conditions. As such, FcRn blockade is a novel and effective strategy to reduce circulating levels of pathogenic IgG autoantibodies and curtail IgG-mediated diseases, with several FcRn-blocking strategies on the path to therapeutic use. Here, we describe the current state of knowledge of FcRn-IgG immunobiology, with an emphasis on the functional and pathological aspects, and an overview of FcRn-targeted therapy development.
Topics: Infant, Newborn; Humans; Immunoglobulin G; Receptors, Fc; Histocompatibility Antigens Class I; Antigens
PubMed: 36726033
DOI: 10.1038/s41577-022-00821-1 -
Journal of Hematology & Oncology Jul 2023Immune cell engagers are engineered antibodies with at least one arm binding a tumor-associated antigen and at least another one directed against an activating receptor... (Review)
Review
Immune cell engagers are engineered antibodies with at least one arm binding a tumor-associated antigen and at least another one directed against an activating receptor in immune effector cells: CD3 for recruitment of T cells and CD16a for NK cells. The first T cell engager (the anti-CD19 blinatumomab) was approved by the FDA in 2014, but no other one hit the market until 2022. Now the field is gaining momentum, with three approvals in 2022 and 2023 (as of May): the anti-CD20 × anti-CD3 mosunetuzumab and epcoritamab and the anti-B cell maturation antigen (BCMA) × anti-CD3 teclistamab, and another three molecules in regulatory review. T cell engagers will likely revolutionize the treatment of hematological malignancies in the short term, as they are considerably more potent than conventional monoclonal antibodies recognizing the same tumor antigens. The field is thriving, with a plethora of different formats and targets, and around 100 bispecific T cell engagers more are already in clinical trials. Bispecific NK cell engagers are also in early-stage clinical studies and may offer similar efficacy with milder side effects. Trispecific antibodies (engaging either T cell or NK cell receptors) raise the game even further with a third binding moiety, which allows either the targeting of an additional tumor-associated antigen to increase specificity and avoid immune escape or the targeting of additional costimulatory receptors on the immune cell to improve its effector functions. Altogether, these engineered molecules may change the paradigm of treatment for relapsed or refractory hematological malignancies.
Topics: Humans; T-Lymphocytes; Antibodies, Bispecific; Immunotherapy; Hematologic Neoplasms; Killer Cells, Natural; Antigens, CD19; Antineoplastic Agents; Antigens, Neoplasm
PubMed: 37501154
DOI: 10.1186/s13045-023-01482-w -
Cell Oct 2023The CD1 system binds lipid antigens for display to T cells. Here, we solved lipidomes for the four human CD1 antigen-presenting molecules, providing a map of self-lipid...
The CD1 system binds lipid antigens for display to T cells. Here, we solved lipidomes for the four human CD1 antigen-presenting molecules, providing a map of self-lipid display. Answering a basic question, the detection of >2,000 CD1-lipid complexes demonstrates broad presentation of self-sphingolipids and phospholipids. Whereas peptide antigens are chemically processed, many lipids are presented in an unaltered form. However, each type of CD1 protein differentially edits the self-lipidome to show distinct capture motifs based on lipid length and chemical composition, suggesting general antigen display mechanisms. For CD1a and CD1d, lipid size matches the CD1 cleft volume. CD1c cleft size is more variable, and CD1b is the outlier, where ligands and clefts show an extreme size mismatch that is explained by uniformly seating two small lipids in one cleft. Furthermore, the list of compounds that comprise the integrated CD1 lipidome supports the ongoing discovery of lipid blockers and antigens for T cells.
Topics: Humans; Antigen Presentation; Antigens, CD1; Lipidomics; Lipids; T-Lymphocytes; Amino Acid Motifs
PubMed: 37725977
DOI: 10.1016/j.cell.2023.08.022 -
Science (New York, N.Y.) Jun 2023During initiation of antiviral and antitumor T cell-mediated immune responses, dendritic cells (DCs) cross-present exogenous antigens on major histocompatibility complex...
During initiation of antiviral and antitumor T cell-mediated immune responses, dendritic cells (DCs) cross-present exogenous antigens on major histocompatibility complex (MHC) class I molecules. Cross-presentation relies on the unusual "leakiness" of endocytic compartments in DCs, whereby internalized proteins escape into the cytosol for proteasome-mediated generation of MHC I-binding peptides. Given that type 1 conventional DCs excel at cross-presentation, we searched for cell type-specific effectors of endocytic escape. We devised an assay suitable for genetic screening and identified a pore-forming protein, perforin-2 (), as a dedicated effector exclusive to cross-presenting cells. Perforin-2 was recruited to antigen-containing compartments, where it underwent maturation, releasing its pore-forming domain. mice failed to efficiently prime CD8 T cells to cell-associated antigens, revealing an important role for perforin-2 in cytosolic entry of antigens during cross-presentation.
Topics: Animals; Mice; Antigen Presentation; Antigens; CD8-Positive T-Lymphocytes; Cross-Priming; Dendritic Cells; Endocytosis; Genetic Testing; Histocompatibility Antigens Class I; Pore Forming Cytotoxic Proteins; Proteolysis
PubMed: 37347855
DOI: 10.1126/science.adg8802 -
Blood Aug 2023Among the risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), ABO(H) blood group antigens are among the most recognized predictors of...
Among the risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), ABO(H) blood group antigens are among the most recognized predictors of infection. However, the mechanisms by which ABO(H) antigens influence susceptibility to COVID-19 remain incompletely understood. The receptor-binding domain (RBD) of SARS-CoV-2, which facilitates host cell engagement, bears significant similarity to galectins, an ancient family of carbohydrate-binding proteins. Because ABO(H) blood group antigens are carbohydrates, we compared the glycan-binding specificity of SARS-CoV-2 RBD with that of galectins. Similar to the binding profile of several galectins, the RBDs of SARS-CoV-2, including Delta and Omicron variants, exhibited specificity for blood group A. Not only did each RBD recognize blood group A in a glycan array format, but each SARS-CoV-2 virus also displayed a preferential ability to infect blood group A-expressing cells. Preincubation of blood group A cells with a blood group-binding galectin specifically inhibited the blood group A enhancement of SARS-CoV-2 infection, whereas similar incubation with a galectin that does not recognize blood group antigens failed to impact SARS-CoV-2 infection. These results demonstrated that SARS-CoV-2 can engage blood group A, providing a direct link between ABO(H) blood group expression and SARS-CoV-2 infection.
Topics: Humans; COVID-19; SARS-CoV-2; ABO Blood-Group System; Galectins
PubMed: 37367252
DOI: 10.1182/blood.2022018903 -
Immunity Nov 2023The accurate selection of neoantigens that bind to class I human leukocyte antigen (HLA) and are recognized by autologous T cells is a crucial step in many cancer...
The accurate selection of neoantigens that bind to class I human leukocyte antigen (HLA) and are recognized by autologous T cells is a crucial step in many cancer immunotherapy pipelines. We reprocessed whole-exome sequencing and RNA sequencing (RNA-seq) data from 120 cancer patients from two external large-scale neoantigen immunogenicity screening assays combined with an in-house dataset of 11 patients and identified 46,017 somatic single-nucleotide variant mutations and 1,781,445 neo-peptides, of which 212 mutations and 178 neo-peptides were immunogenic. Beyond features commonly used for neoantigen prioritization, factors such as the location of neo-peptides within protein HLA presentation hotspots, binding promiscuity, and the role of the mutated gene in oncogenicity were predictive for immunogenicity. The classifiers accurately predicted neoantigen immunogenicity across datasets and improved their ranking by up to 30%. Besides insights into machine learning methods for neoantigen ranking, we have provided homogenized datasets valuable for developing and benchmarking companion algorithms for neoantigen-based immunotherapies.
Topics: Humans; Antigens, Neoplasm; Neoplasms; Histocompatibility Antigens Class I; Machine Learning; Peptides; Immunotherapy
PubMed: 37816353
DOI: 10.1016/j.immuni.2023.09.002 -
Immunity Jun 2023CD4 T cells orchestrate the adaptive immune response against pathogens and cancer by recognizing epitopes presented on class II major histocompatibility complex...
CD4 T cells orchestrate the adaptive immune response against pathogens and cancer by recognizing epitopes presented on class II major histocompatibility complex (MHC-II) molecules. The high polymorphism of MHC-II genes represents an important hurdle toward accurate prediction and identification of CD4 T cell epitopes. Here we collected and curated a dataset of 627,013 unique MHC-II ligands identified by mass spectrometry. This enabled us to precisely determine the binding motifs of 88 MHC-II alleles across humans, mice, cattle, and chickens. Analysis of these binding specificities combined with X-ray crystallography refined our understanding of the molecular determinants of MHC-II motifs and revealed a widespread reverse-binding mode in HLA-DP ligands. We then developed a machine-learning framework to accurately predict binding specificities and ligands of any MHC-II allele. This tool improves and expands predictions of CD4 T cell epitopes and enables us to discover viral and bacterial epitopes following the aforementioned reverse-binding mode.
Topics: Humans; Animals; Mice; Cattle; Epitopes, T-Lymphocyte; Ligands; Peptides; Protein Binding; Chickens; Machine Learning; Histocompatibility Antigens Class II; Alleles
PubMed: 37023751
DOI: 10.1016/j.immuni.2023.03.009 -
Proceedings of the National Academy of... Jul 2023A common event upon receptor-ligand engagement is the formation of receptor clusters on the cell surface, in which signaling molecules are specifically recruited or...
A common event upon receptor-ligand engagement is the formation of receptor clusters on the cell surface, in which signaling molecules are specifically recruited or excluded to form signaling hubs to regulate cellular events. These clusters are often transient and can be disassembled to terminate signaling. Despite the general relevance of dynamic receptor clustering in cell signaling, the regulatory mechanism underlying the dynamics is still poorly understood. As a major antigen receptor in the immune system, T cell receptors (TCR) form spatiotemporally dynamic clusters to mediate robust yet temporal signaling to induce adaptive immune responses. Here we identify a phase separation mechanism controlling dynamic TCR clustering and signaling. The TCR signaling component CD3ε chain can condensate with Lck kinase through phase separation to form TCR signalosomes for active antigen signaling. Lck-mediated CD3ε phosphorylation, however, switched its binding preference to Csk, a functional suppressor of Lck, to cause the dissolvement of TCR signalosomes. Modulating TCR/Lck condensation by targeting CD3ε interactions with Lck or Csk directly affects T cell activation and function, highlighting the importance of the phase separation mechanism. The self-programmed condensation and dissolvement is thus a built-in mechanism of TCR signaling and might be relevant to other receptors.
Topics: Receptors, Antigen, T-Cell; Lymphocyte Specific Protein Tyrosine Kinase p56(lck); Signal Transduction; Phosphorylation; Antigens
PubMed: 37399423
DOI: 10.1073/pnas.2217301120 -
Nature Sep 2023Despite the considerable efficacy observed when targeting a dispensable lineage antigen, such as CD19 in B cell acute lymphoblastic leukaemia, the broader applicability...
Despite the considerable efficacy observed when targeting a dispensable lineage antigen, such as CD19 in B cell acute lymphoblastic leukaemia, the broader applicability of adoptive immunotherapies is hampered by the absence of tumour-restricted antigens. Acute myeloid leukaemia immunotherapies target genes expressed by haematopoietic stem/progenitor cells (HSPCs) or differentiated myeloid cells, resulting in intolerable on-target/off-tumour toxicity. Here we show that epitope engineering of donor HSPCs used for bone marrow transplantation endows haematopoietic lineages with selective resistance to chimeric antigen receptor (CAR) T cells or monoclonal antibodies, without affecting protein function or regulation. This strategy enables the targeting of genes that are essential for leukaemia survival regardless of shared expression on HSPCs, reducing the risk of tumour immune escape. By performing epitope mapping and library screenings, we identified amino acid changes that abrogate the binding of therapeutic monoclonal antibodies targeting FLT3, CD123 and KIT, and optimized a base-editing approach to introduce them into CD34 HSPCs, which retain long-term engraftment and multilineage differentiation ability. After CAR T cell treatment, we confirmed resistance of epitope-edited haematopoiesis and concomitant eradication of patient-derived acute myeloid leukaemia xenografts. Furthermore, we show that multiplex epitope engineering of HSPCs is feasible and enables more effective immunotherapies against multiple targets without incurring overlapping off-tumour toxicities. We envision that this approach will provide opportunities to treat relapsed/refractory acute myeloid leukaemia and enable safer non-genotoxic conditioning.
Topics: Animals; Humans; Antibodies, Monoclonal; Antigens, CD34; Bone Marrow Transplantation; Epitope Mapping; Epitopes; Gene Editing; Hematopoiesis; Hematopoietic Stem Cells; Heterografts; Immunotherapy; Leukemia, Myeloid, Acute; Receptors, Chimeric Antigen; Recurrence; T-Lymphocytes; Transplantation Conditioning; Tumor Escape; Xenograft Model Antitumor Assays
PubMed: 37648862
DOI: 10.1038/s41586-023-06496-5