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1.
J Immunol ; 213(6): 876-885, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-39093013

RESUMEN

The central immunological role of HLA class I (HLA-I) in presenting peptide Ags to cellular components of the immune system has been the focus of intense study for >60 y. A confounding factor in the study of HLA-I has been the extreme polymorphism of these molecules. The mAb W6/32 has been a fundamental reagent bypassing the issue of polymorphism by recognizing an epitope that is conserved across diverse HLA-I allotypes. However, despite the widespread use of W6/32, the epitope of this Ab has not been definitively mapped. In this study, we present the crystal structure of the Fab fragment of W6/32 in complex with peptide-HLA-B*27:05. W6/32 bound to HLA-B*27:05 beneath the Ag-binding groove, recognizing a discontinuous epitope comprised of the α1, α2, and α3 domains of HLA-I and ß2-microglobulin. The epitope comprises a region of low polymorphism reflecting the pan-HLA-I nature of the binding. Notably, the W6/32 epitope neither overlaps the HLA-I binding sites of either T cell Ag receptors or killer cell Ig-like receptors. However, it does coincide with the binding sites for leukocyte Ig-like receptors and CD8 coreceptors. Consistent with this, the use of W6/32 to block the interaction of NK cells with HLA-I only weakly impaired inhibition mediated by KIR3DL1, but impacted HLA-LILR recognition.


Asunto(s)
Anticuerpos Monoclonales , Humanos , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/química , Cristalografía por Rayos X , Antígenos HLA-B/inmunología , Antígenos HLA-B/química , Antígenos HLA-B/genética , Unión Proteica , Epítopos/inmunología , Fragmentos Fab de Inmunoglobulinas/inmunología , Fragmentos Fab de Inmunoglobulinas/química , Antígenos de Histocompatibilidad Clase I/inmunología , Antígenos de Histocompatibilidad Clase I/química , Antígeno HLA-B27
2.
J Immunol ; 206(4): 849-860, 2021 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-33441440

RESUMEN

HLA class I molecules that represent ligands for the inhibitory killer cell Ig-like receptor (KIR) 3DL1 found on NK cells are categorically defined as those HLA-A and HLA-B allotypes containing the Bw4 motif, yet KIR3DL1 demonstrates hierarchical recognition of these HLA-Bw4 ligands. To better understand the molecular basis underpinning differential KIR3DL1 recognition, the HLA-ABw4 family of allotypes were investigated. Transfected human 721.221 cells expressing HLA-A*32:01 strongly inhibited primary human KIR3DL1+ NK cells, whereas HLA-A*24:02 and HLA-A*23:01 displayed intermediate potency and HLA-A*25:01 failed to inhibit activation of KIR3DL1+ NK cells. Structural studies demonstrated that recognition of HLA-A*24:02 by KIR3DL1 used identical contacts as the potent HLA-B*57:01 ligand. Namely, the D1-D2 domains of KIR3DL1 were placed over the α1 helix and α2 helix of the HLA-A*24:02 binding cleft, respectively, whereas the D0 domain contacted the side of the HLA-A*24:02 molecule. Nevertheless, functional analyses showed KIR3DL1 recognition of HLA-A*24:02 was more sensitive to substitutions within the α2 helix of HLA-A*24:02, including residues Ile142 and Lys144 Furthermore, the presence of Thr149 in the α2 helix of HLA-A*25:01 abrogated KIR3DL1+ NK inhibition. Together, these data demonstrate a role for the HLA class I α2 helix in determining the hierarchy of KIR3DL1 ligands. Thus, recognition of HLA class I is dependent on a complex interplay between the peptide repertoire, polymorphisms within and proximal to the Bw4 motif, and the α2 helix. Collectively, the data furthers our understanding of KIR3DL1 ligands and will inform genetic association and immunogenetics studies examining the role of KIR3DL1 in disease settings.


Asunto(s)
Antígenos HLA-A , Células Asesinas Naturales , Receptores KIR3DL1 , Antígenos HLA-A/química , Antígenos HLA-A/inmunología , Humanos , Células Asesinas Naturales/química , Células Asesinas Naturales/inmunología , Conformación Proteica en Hélice alfa , Dominios Proteicos , Receptores KIR3DL1/química , Receptores KIR3DL1/inmunología
3.
Proc Natl Acad Sci U S A ; 117(21): 11636-11647, 2020 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-32404419

RESUMEN

Micropolymorphisms within human leukocyte antigen (HLA) class I molecules can change the architecture of the peptide-binding cleft, leading to differences in peptide presentation and T cell recognition. The impact of such HLA variation on natural killer (NK) cell recognition remains unclear. Given the differential association of HLA-B*57:01 and HLA-B*57:03 with the control of HIV, recognition of these HLA-B57 allomorphs by the killer cell immunoglobulin-like receptor (KIR) 3DL1 was compared. Despite differing by only two polymorphic residues, both buried within the peptide-binding cleft, HLA-B*57:01 more potently inhibited NK cell activation. Direct-binding studies showed KIR3DL1 to preferentially recognize HLA-B*57:01, particularly when presenting peptides with positively charged position (P)Ω-2 residues. In HLA-B*57:01, charged PΩ-2 residues were oriented toward the peptide-binding cleft and away from KIR3DL1. In HLA-B*57:03, the charged PΩ-2 residues protruded out from the cleft and directly impacted KIR3DL1 engagement. Accordingly, KIR3DL1 recognition of HLA class I ligands is modulated by both the peptide sequence and conformation, as determined by the HLA polymorphic framework, providing a rationale for understanding differences in clinical associations.


Asunto(s)
Antígenos de Histocompatibilidad Clase I/genética , Células Asesinas Naturales/fisiología , Polimorfismo Genético/genética , Antígenos de Histocompatibilidad Clase I/química , Antígenos de Histocompatibilidad Clase I/fisiología , Humanos , Activación de Linfocitos/genética , Modelos Moleculares , Polimorfismo Genético/fisiología , Receptores KIR/genética
4.
Eur J Immunol ; 51(2): 331-341, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32920841

RESUMEN

Immune checkpoint inhibitors (antibodies that block the T cell co-inhibitory receptors PD-1/PD-L1 or CTLA-4) have revolutionized the treatment of some forms of cancer. Importantly, combination approaches using drugs that target both pathways have been shown to boost the efficacy of such treatments. Subsequently, several other T cell inhibitory receptors have been identified for the development of novel immune checkpoint inhibitors. Included in this list is the co-inhibitory receptor lymphocyte activation gene-3 (LAG-3), which is upregulated on T cells extracted from tumor sites that have suppressive or exhausted phenotypes. However, the molecular rules that govern the function of LAG-3 are still not understood. Using surface plasmon resonance combined with a novel bead-based assay (AlphaScreenTM ), we demonstrate that LAG-3 can directly and specifically interact with intact human leukocyte antigen class II (HLA-II) heterodimers. Unlike the homologue CD4, which has an immeasurably weak affinity using these biophysical approaches, LAG-3 binds with low micromolar affinity. We further validated the interaction at the cell surface by staining LAG-3+ cells with pHLA-II-multimers. These data provide new insights into the mechanism by which LAG-3 initiates T cell inhibition.


Asunto(s)
Antígenos CD/inmunología , Receptores Coestimuladores e Inhibidores de Linfocitos T/inmunología , Antígenos HLA/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/inmunología , Antígenos CD4/inmunología , Línea Celular Tumoral , Humanos , Inhibidores de Puntos de Control Inmunológico/inmunología , Células Jurkat , Neoplasias/inmunología , Proteína del Gen 3 de Activación de Linfocitos
5.
J Biol Chem ; 294(52): 20246-20258, 2019 12 27.
Artículo en Inglés | MEDLINE | ID: mdl-31619516

RESUMEN

CD4+ T-cells recognize peptide antigens, in the context of human leukocyte antigen (HLA) class II molecules (HLA-II), which through peptide-flanking residues (PFRs) can extend beyond the limits of the HLA binding. The role of the PFRs during antigen recognition is not fully understood; however, recent studies have indicated that these regions can influence T-cell receptor (TCR) affinity and pHLA-II stability. Here, using various biochemical approaches including peptide sensitivity ELISA and ELISpot assays, peptide-binding assays and HLA-II tetramer staining, we focused on CD4+ T-cell responses against a tumor antigen, 5T4 oncofetal trophoblast glycoprotein (5T4), which have been associated with improved control of colorectal cancer. Despite their weak TCR-binding affinity, we found that anti-5T4 CD4+ T-cells are polyfunctional and that their PFRs are essential for TCR recognition of the core bound nonamer. The high-resolution (1.95 Å) crystal structure of HLA-DR1 presenting the immunodominant 20-mer peptide 5T4111-130, combined with molecular dynamic simulations, revealed how PFRs explore the HLA-proximal space to contribute to antigen reactivity. These findings advance our understanding of what constitutes an HLA-II epitope and indicate that PFRs can tune weak affinity TCR-pHLA-II interactions.


Asunto(s)
Epítopos/inmunología , Antígeno HLA-DR1/metabolismo , Secuencia de Aminoácidos , Sitios de Unión , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Cristalografía por Rayos X , Epítopos/química , Epítopos/metabolismo , Antígeno HLA-DR1/química , Antígeno HLA-DR1/inmunología , Humanos , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/metabolismo , Simulación de Dinámica Molecular , Péptidos/química , Péptidos/metabolismo , Unión Proteica , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína
6.
Biochem Soc Trans ; 48(6): 2625-2641, 2020 12 18.
Artículo en Inglés | MEDLINE | ID: mdl-33258925

RESUMEN

The race to identify a successful treatment for COVID19 will be defined by fundamental research into the replication cycle of the SARS-CoV-2 virus. This has identified five distinct stages from which numerous vaccination and clinical trials have emerged alongside an innumerable number of drug discovery studies currently in development for disease intervention. Informing every step of the viral replication cycle has been an unprecedented 'call-to-arms' by the global structural biology community. Of the 20 main SARS-CoV-2 proteins, 13 have been resolved structurally for SARS-CoV-2 with most having a related SARS-CoV and MERS-CoV structural homologue totalling some 300 structures currently available in public repositories. Herein, we review the contribution of structural studies to our understanding of the virus and their role in structure-based development of therapeutics.


Asunto(s)
Antivirales/química , Antivirales/uso terapéutico , COVID-19/terapia , Descubrimiento de Drogas/métodos , SARS-CoV-2 , Antivirales/síntesis química , COVID-19/inmunología , Desarrollo de Medicamentos/métodos , Genoma Viral , Humanos , Modelos Moleculares , Elementos Estructurales de las Proteínas , SARS-CoV-2/química , SARS-CoV-2/efectos de los fármacos , SARS-CoV-2/inmunología , SARS-CoV-2/fisiología , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/fisiología , Relación Estructura-Actividad , Proteínas Estructurales Virales/química , Proteínas Estructurales Virales/fisiología , Replicación Viral/efectos de los fármacos , Replicación Viral/fisiología , Tratamiento Farmacológico de COVID-19
7.
Cancer Immunol Immunother ; 68(2): 247-256, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30406375

RESUMEN

The oncofoetal antigen 5T4 is a promising T cell target in the context of colorectal cancer, as demonstrated by a recent clinical study where 5T4-specific T cell responses, induced by vaccination or cyclophosphamide, were associated with a significantly prolonged survival of patients with metastatic disease. Whilst Th1-type (IFN-γ+) responses specific to 5T4, and other oncofoetal antigens, are often readily detectable in early stage CRC patients and healthy donors, their activity is suppressed as the cancer progresses by CD4+CD25hiFoxp3+ regulatory T cells (Treg) which contribute to the immunosuppressive environment conducive to tumour growth. This study mapped the fine specificity of Th1 and Treg cell responses to the 5T4 protein. Surprisingly, both immunogenic peptides and those recognised by Tregs clustered in the same HLA-DR transcending epitope-rich hotspots within the 5T4 protein. Similarly, regions of low Th1-cell immunogenicity also did not contain peptides capable of stimulating Tregs, further supporting the notion that Treg and Th1 cells recognise the same peptides. Understanding the rules which govern the balance of Th1 and Treg cells responding to a given peptide specificity is, therefore, of fundamental importance to designing strategies for manipulating the balance in favour of Th1 cells, and thus the most effective anti-cancer T cell responses.


Asunto(s)
Antígenos de Neoplasias/inmunología , Vacunas contra el Cáncer/inmunología , Neoplasias Colorrectales/inmunología , Linfocitos T Reguladores/inmunología , Linfocitos T/inmunología , Antígenos de Neoplasias/metabolismo , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Células Cultivadas , Neoplasias Colorrectales/metabolismo , Diseño de Fármacos , Epítopos/inmunología , Epítopos/metabolismo , Antígenos HLA-DR/inmunología , Humanos , Interferón gamma/inmunología , Interferón gamma/metabolismo , Péptidos/inmunología , Péptidos/metabolismo , Linfocitos T/metabolismo , Linfocitos T Reguladores/metabolismo , Células TH1/inmunología , Células TH1/metabolismo
8.
FEBS J ; 291(7): 1530-1544, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38158698

RESUMEN

The heterodimeric natural killer cells antigen CD94 (CD94)-NKG2-A/NKG2-B type II integral membrane protein (NKG2A) receptor family expressed on human and mouse natural killer (NK) cells monitors global major histocompatibility complex (MHC) class I cell surface expression levels through binding to MHC class Ia-derived leader sequence peptides presented by HLA class I histocompatibility antigen, alpha chain E (HLA-E; in humans) or H-2 class I histocompatibility antigen, D-37 (Qa-1b; in mice). Although the molecular basis underpinning human CD94-NKG2A recognition of HLA-E is known, the equivalent interaction in the murine setting is not. By determining the high-resolution crystal structure of murine CD94-NKG2A in complex with Qa-1b presenting the Qa-1 determinant modifier peptide (QDM), we resolved the mode of binding. Compared to the human homologue, the murine CD94-NKG2A-Qa-1b-QDM displayed alterations in the distribution of interactions across CD94 and NKG2A subunits that coincide with differences in electrostatic complementarity of the ternary complex and the lack of cross-species reactivity. Nevertheless, we show that Qa-1b could be modified through W65R + N73I mutations to mimic HLA-E, facilitating binding with both human and murine CD94-NKG2A. These data underscore human and murine CD94-NKG2A cross-species heterogeneity and provide a foundation for humanising Qa-1b in immune system models.


Asunto(s)
Antígenos HLA-E , Señales de Clasificación de Proteína , Animales , Humanos , Ratones , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/metabolismo , Antígenos HLA/genética , Antígenos HLA/metabolismo , Células Asesinas Naturales , Subfamília C de Receptores Similares a Lectina de Células NK/genética , Subfamília C de Receptores Similares a Lectina de Células NK/metabolismo , Subfamília D de Receptores Similares a Lectina de las Células NK/genética , Subfamília D de Receptores Similares a Lectina de las Células NK/química , Péptidos/metabolismo , Receptores de Células Asesinas Naturales/metabolismo
9.
Cell Rep ; 43(6): 114259, 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38819988

RESUMEN

CD4+ T cells are central to adaptive immunity. Their role in cross-protection in viral infections such as influenza and severe acute respiratory syndrome (SARS) is well documented; however, molecular rules governing T cell receptor (TCR) engagement of peptide-human leukocyte antigen (pHLA) class II are less understood. Here, we exploit an aspect of HLA class II presentation, the peptide-flanking residues (PFRs), to "tune" CD4+ T cell responses within an in vivo model system of influenza. Using a recombinant virus containing targeted substitutions at immunodominant HLA-DR1 epitopes, we demonstrate limited weight loss and improved clinical scores after heterosubtypic re-challenge. We observe enhanced protection linked to lung-derived influenza-specific CD4+ and CD8+ T cells prior to re-infection. Structural analysis of the ternary TCR:pHLA complex identifies that flanking amino acids influence side chains in the core 9-mer peptide, increasing TCR affinity. Augmentation of CD4+ T cell immunity is achievable with a single mutation, representing a strategy to enhance adaptive immunity that is decoupled from vaccine modality.


Asunto(s)
Linfocitos T CD4-Positivos , Virus de la Influenza A , Mutación , Receptores de Antígenos de Linfocitos T , Animales , Femenino , Humanos , Ratones , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Epítopos/inmunología , Virus de la Influenza A/inmunología , Virus de la Influenza A/genética , Gripe Humana/inmunología , Gripe Humana/virología , Gripe Humana/prevención & control , Activación de Linfocitos/inmunología , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/virología , Receptores de Antígenos de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Receptores de Antígenos de Linfocitos T/genética
10.
Cell Rep ; 42(8): 112827, 2023 08 29.
Artículo en Inglés | MEDLINE | ID: mdl-37471227

RESUMEN

CD4+ T cells recognize a broad range of peptide epitopes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which contribute to immune memory and limit COVID-19 disease. We demonstrate that the immunogenicity of SARS-CoV-2 peptides, in the context of the model allotype HLA-DR1, does not correlate with their binding affinity to the HLA heterodimer. Analyzing six epitopes, some with very low binding affinity, we solve X-ray crystallographic structures of each bound to HLA-DR1. Further structural definitions reveal the precise molecular impact of viral variant mutations on epitope presentation. Omicron escaped ancestral SARS-CoV-2 immunity to two epitopes through two distinct mechanisms: (1) mutations to TCR-facing epitope positions and (2) a mechanism whereby a single amino acid substitution caused a register shift within the HLA binding groove, completely altering the peptide-HLA structure. This HLA-II-specific paradigm of immune escape highlights how CD4+ T cell memory is finely poised at the level of peptide-HLA-II presentation.


Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , Antígeno HLA-DR1 , Epítopos de Linfocito T , Péptidos , Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos
11.
Discov Immunol ; 1(1): kyac001, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-38566908

RESUMEN

The intracellular proteome of virtually every nucleated cell in the body is continuously presented at the cell surface via the human leukocyte antigen class I (HLA-I) antigen processing pathway. This pathway classically involves proteasomal degradation of intracellular proteins into short peptides that can be presented by HLA-I molecules for interrogation by T-cell receptors (TCRs) expressed on the surface of CD8+ T cells. During the initiation of a T-cell immune response, the TCR acts as the T cell's primary sensor, using flexible loops to mould around the surface of the pHLA-I molecule to identify foreign or dysregulated antigens. Recent findings demonstrate that pHLA-I molecules can also be highly flexible and dynamic, altering their shape according to minor polymorphisms between different HLA-I alleles, or interactions with different peptides. These flexible presentation modes have important biological consequences that can, for example, explain why some HLA-I alleles offer greater protection against HIV, or why some cancer vaccine approaches have been ineffective. This review explores how these recent findings redefine the rules for peptide presentation by HLA-I molecules and extend our understanding of the molecular mechanisms that govern TCR-mediated antigen discrimination.

12.
Immunother Adv ; 2(1): ltab025, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35265944

RESUMEN

Despite three decades of research to its name and increasing interest in immunotherapies that target it, LAG-3 remains an elusive co-inhibitory receptor in comparison to the well-established PD-1 and CTLA-4. As such, LAG-3 targeting therapies have yet to achieve the clinical success of therapies targeting other checkpoints. This could, in part, be attributed to the many unanswered questions that remain regarding LAG-3 biology. Of these, we address: (i) the function of the many LAG-3-ligand interactions, (ii) the hurdles that remain to acquire a high-resolution structure of LAG-3, (iii) the under-studied LAG-3 signal transduction mechanism, (iv) the elusive soluble form of LAG-3, (v) the implications of the lack of (significant) phenotype of LAG-3 knockout mice, (vi) the reports of LAG-3 expression on the epithelium, and (vii) the conflicting reports of LAG-3 expression (and potential contributions to pathology) in the brain. These mysteries which surround LAG-3 highlight how the ever-evolving study of its biology continues to reveal ever-increasing complexity in its role as an immune receptor. Importantly, answering the questions which shroud LAG-3 in mystery will allow the maximum therapeutic benefit of LAG-3 targeting immunotherapies in cancer, autoimmunity and beyond.

13.
Nat Commun ; 12(1): 2173, 2021 04 12.
Artículo en Inglés | MEDLINE | ID: mdl-33846289

RESUMEN

The closely related inhibitory killer-cell immunoglobulin-like receptors (KIR), KIR2DL2 and KIR2DL3, regulate the activation of natural killer cells (NK) by interacting with the human leukocyte antigen-C1 (HLA-C1) group of molecules. KIR2DL2, KIR2DL3 and HLA-C1 are highly polymorphic, with this variation being associated with differences in the onset and progression of some human diseases. However, the molecular bases underlying these associations remain unresolved. Here, we determined the crystal structures of KIR2DL2 and KIR2DL3 in complex with HLA-C*07:02 presenting a self-epitope. KIR2DL2 differed from KIR2DL3 in docking modality over HLA-C*07:02 that correlates with variabilty of recognition of HLA-C1 allotypes. Mutagenesis assays indicated differences in the mechanism of HLA-C1 allotype recognition by KIR2DL2 and KIR2DL3. Similarly, HLA-C1 allotypes differed markedly in their capacity to inhibit activation of primary NK cells. These functional differences derive, in part, from KIR2DS2 suggesting KIR2DL2 and KIR2DL3 binding geometries combine with other factors to distinguish HLA-C1 functional recognition.


Asunto(s)
Antígenos HLA-C/metabolismo , Simulación del Acoplamiento Molecular , Receptores KIR2DL2/química , Receptores KIR2DL2/metabolismo , Receptores KIR2DL3/química , Receptores KIR2DL3/metabolismo , Células HEK293 , Humanos , Células Asesinas Naturales/inmunología , Ligandos , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Péptidos/química , Unión Proteica , Mapeo de Interacción de Proteínas
14.
Mol Ther Oncolytics ; 18: 443-456, 2020 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-32913893

RESUMEN

Immuno-oncology approaches that utilize T cell receptors (TCRs) are becoming highly attractive because of their potential to target virtually all cellular proteins, including cancer-specific epitopes, via the recognition of peptide-human leukocyte antigen (pHLA) complexes presented at the cell surface. However, because natural TCRs generally recognize cancer-derived pHLAs with very weak affinities, efforts have been made to enhance their binding strength, in some cases by several million-fold. In this study, we investigated the mechanisms underpinning human TCR affinity enhancement by comparing the crystal structures of engineered enhanced affinity TCRs with those of their wild-type progenitors. Additionally, we performed molecular dynamics simulations to better understand the energetic mechanisms driving the affinity enhancements. These data demonstrate that supra-physiological binding affinities can be achieved without altering native TCR-pHLA binding modes via relatively subtle modifications to the interface contacts, often driven through the addition of buried hydrophobic residues. Individual energetic components of the TCR-pHLA interaction governing affinity enhancements were distinct and highly variable for each TCR, often resulting from additive, or knock-on, effects beyond the mutated residues. This comprehensive analysis of affinity-enhanced TCRs has important implications for the future rational design of engineered TCRs as efficacious and safe drugs for cancer treatment.

15.
Cell Rep ; 32(2): 107885, 2020 07 14.
Artículo en Inglés | MEDLINE | ID: mdl-32668259

RESUMEN

T cell recognition of peptides presented by human leukocyte antigens (HLAs) is mediated by the highly variable T cell receptor (TCR). Despite this built-in TCR variability, individuals can mount immune responses against viral epitopes by using identical or highly related TCRs expressed on CD8+ T cells. Characterization of these TCRs has extended our understanding of the molecular mechanisms that govern the recognition of peptide-HLA. However, few examples exist for CD4+ T cells. Here, we investigate CD4+ T cell responses to the internal proteins of the influenza A virus that correlate with protective immunity. We identify five internal epitopes that are commonly recognized by CD4+ T cells in five HLA-DR1+ subjects and show conservation across viral strains and zoonotic reservoirs. TCR repertoire analysis demonstrates several shared gene usage biases underpinned by complementary biochemical features evident in a structural comparison. These epitopes are attractive targets for vaccination and other T cell therapies.


Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Epítopos/inmunología , Región Variable de Inmunoglobulina/genética , Virus de la Influenza A/inmunología , Adulto , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Aves/virología , Regiones Determinantes de Complementariedad/química , Secuencia Conservada , Epítopos/química , Femenino , Células Germinativas/metabolismo , Antígeno HLA-DR1/inmunología , Humanos , Epítopos Inmunodominantes/química , Epítopos Inmunodominantes/inmunología , Masculino , Persona de Mediana Edad , Péptidos/química , Péptidos/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Porcinos/virología , Donantes de Tejidos , Proteínas Virales/inmunología , Adulto Joven , Zoonosis/inmunología , Zoonosis/virología
16.
Front Immunol ; 9: 674, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29696015

RESUMEN

T-cell immunity is controlled by T cell receptor (TCR) binding to peptide major histocompatibility complexes (pMHCs). The nature of the interaction between these two proteins has been the subject of many investigations because of its central role in immunity against pathogens, cancer, in autoimmunity, and during organ transplant rejection. Crystal structures comparing unbound and pMHC-bound TCRs have revealed flexibility at the interaction interface, particularly from the perspective of the TCR. However, crystal structures represent only a snapshot of protein conformation that could be influenced through biologically irrelevant crystal lattice contacts and other factors. Here, we solved the structures of three unbound TCRs from multiple crystals. Superposition of identical TCR structures from different crystals revealed some conformation differences of up to 5 Å in individual complementarity determining region (CDR) loops that are similar to those that have previously been attributed to antigen engagement. We then used a combination of rigidity analysis and simulations of protein motion to reveal the theoretical potential of TCR CDR loop flexibility in unbound state. These simulations of protein motion support the notion that crystal structures may only offer an artifactual indication of TCR flexibility, influenced by crystallization conditions and crystal packing that is inconsistent with the theoretical potential of intrinsic TCR motions.


Asunto(s)
Regiones Determinantes de Complementariedad , Receptores de Antígenos de Linfocitos T/química , Simulación por Computador , Cristalización , Cristalografía por Rayos X , Conformación Proteica
17.
J Vis Exp ; (120)2017 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-28287509

RESUMEN

Human CD8+ cytotoxic T lymphocytes (CTLs) are known to play an important role in tumor control. In order to carry out this function, the cell surface-expressed T-cell receptor (TCR) must functionally recognize human leukocyte antigen (HLA)-restricted tumor-derived peptides (pHLA). However, we and others have shown that most TCRs bind sub-optimally to tumor antigens. Uncovering the molecular mechanisms that define this poor recognition could aid in the development of new targeted therapies that circumnavigate these shortcomings. Indeed, present therapies that lack this molecular understanding have not been universally effective. Here, we describe methods that we commonly employ in the laboratory to determine how the nature of the interaction between TCRs and pHLA governs T-cell functionality. These methods include the generation of soluble TCRs and pHLA and the use of these reagents for X-ray crystallography, biophysical analysis, and antigen-specific T-cell staining with pHLA multimers. Using these approaches and guided by structural analysis, it is possible to modify the interaction between TCRs and pHLA and to then test how these modifications impact T-cell antigen recognition. These findings have already helped to clarify the mechanism of T-cell recognition of a number of cancer antigens and could direct the development of altered peptides and modified TCRs for new cancer therapies.


Asunto(s)
Antígenos de Neoplasias/análisis , Biofisica/métodos , Cristalografía por Rayos X/métodos , Inmunidad Celular , Neoplasias/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Humanos , Neoplasias/diagnóstico
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