RESUMEN
IgG antibodies mediate a diversity of immune functions by coupling of antigen specificity through the Fab domain to signal transduction via Fc-Fc receptor interactions. Indeed, balanced IgG signaling through type I and type II Fc receptors is required for the control of proinflammatory, anti-inflammatory, and immunomodulatory processes. In this review, we discuss the mechanisms that govern IgG-Fc receptor interactions, highlighting the diversity of Fc receptor-mediated effector functions that regulate immunity and inflammation as well as determine susceptibility to infection and autoimmunity and responsiveness to antibody-based therapeutics and vaccines.
Asunto(s)
Anticuerpos/uso terapéutico , Enfermedades Autoinmunes/inmunología , Inmunoglobulina G/metabolismo , Inmunoterapia/métodos , Infecciones/inmunología , Receptores Fc/metabolismo , Animales , Enfermedades Autoinmunes/terapia , Susceptibilidad a Enfermedades , Humanos , Inmunidad Humoral , Infecciones/terapia , Inflamación , Transducción de SeñalRESUMEN
Anti-programmed death-1 (anti-PD-1) immunotherapy reinvigorates CD8 T cell responses in patients with cancer but PD-1 is also expressed by other immune cells, including follicular helper CD4 T cells (Tfh) which are involved in germinal centre responses. Little is known, however, about the effects of anti-PD-1 immunotherapy on noncancer immune responses in humans. To investigate this question, we examined the impact of anti-PD-1 immunotherapy on the Tfh-B cell axis responding to unrelated viral antigens. Following influenza vaccination, a subset of adults receiving anti-PD-1 had more robust circulating Tfh responses than adults not receiving immunotherapy. PD-1 pathway blockade resulted in transcriptional signatures of increased cellular proliferation in circulating Tfh and responding B cells compared with controls. These latter observations suggest an underlying change in the Tfh-B cell and germinal centre axis in a subset of immunotherapy patients. Together, these results demonstrate dynamic effects of anti-PD-1 therapy on influenza vaccine responses and highlight analytical vaccination as an approach that may reveal underlying immune predisposition to adverse events.
Asunto(s)
Vacunas contra la Influenza , Adulto , Humanos , Inmunidad Humoral , Estaciones del Año , Linfocitos T Colaboradores-Inductores , VacunaciónRESUMEN
Broadly neutralizing antibodies (bNAbs) against the HIV-1 envelope glycoprotein (Env) suppress viremia in animal models of HIV-1 and humans. To achieve potent activity without the emergence of viral escape mutants, co-administration of different bNAbs is necessary to target distinct epitopes essential for viral fitness. Here, we report the development of bispecific anti-Env neutralizing antibodies (biNAbs) with potent activity. Synergistic activity of biNAbs was achieved by combining an engineered hinge domain of IgG3 to increase Fab domain flexibility necessary for hetero-bivalent binding to the Env trimer while retaining the functional properties of the IgG1-Fc. Compared to unmodified biNAbs, hinge domain variants exhibited substantially improved neutralization activity, with particular combinations showing evidence of synergistic neutralization potency in vitro and enhanced in vivo therapeutic activity in HIV-1-infected humanized mice. These findings suggest innovative strategies for generating biNAbs with enhanced neutralization breadth and potency, representing ideal candidate molecules for the control of HIV-1 infection.
Asunto(s)
Anticuerpos Biespecíficos/química , Proteína gp120 de Envoltorio del VIH/inmunología , VIH-1/inmunología , Animales , Anticuerpos Biespecíficos/inmunología , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/inmunología , Epítopos , Proteína gp120 de Envoltorio del VIH/química , Infecciones por VIH/prevención & control , Infecciones por VIH/terapia , Humanos , Inmunización Pasiva , Fragmentos Fab de Inmunoglobulinas/química , Fragmentos Fab de Inmunoglobulinas/inmunología , Inmunoglobulina G/química , Inmunoglobulina G/inmunología , RatonesRESUMEN
Passively administered anti-tumor monoclonal antibodies (mAbs) rapidly kill tumor targets via FcγR-mediated cytotoxicity (ADCC), a short-term process. However, anti-tumor mAb treatment can also induce a vaccinal effect, in which mAb-mediated tumor death induces a long-term anti-tumor cellular immune response. To determine how such responses are generated, we utilized a murine model of an anti-tumor vaccinal effect against a model neoantigen. We demonstrate that FcγR expression by CD11c(+) antigen-presenting cells is required to generate anti-tumor T cell responses upon ADCC-mediated tumor clearance. Using FcγR-humanized mice, we demonstrate that anti-tumor human (h)IgG1 must engage hFcγRIIIA on macrophages to mediate ADCC, but also engage hFcγRIIA, the sole hFcγR expressed by human dendritic cells (DCs), to generate a potent vaccinal effect. Thus, while next-generation anti-tumor antibodies with enhanced binding to only hFcγRIIIA are now in clinical use, ideal anti-tumor antibodies must be optimized for both cytotoxic effects as well as hFcγRIIA engagement on DCs to stimulate long-term anti-tumor cellular immunity.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Neoplasias/inmunología , Receptores de IgG/inmunología , Animales , Anticuerpos Monoclonales/administración & dosificación , Citotoxicidad Celular Dependiente de Anticuerpos , Presentación de Antígeno , Antígeno CD11c/inmunología , Vacunas contra el Cáncer/inmunología , Modelos Animales de Enfermedad , Humanos , Macrófagos/inmunología , RatonesRESUMEN
Protective vaccines elicit high-affinity, neutralizing antibodies by selection of somatically hypermutated B cell antigen receptors (BCR) on immune complexes (ICs). This implicates Fc-Fc receptor (FcR) interactions in affinity maturation, which, in turn, are determined by IgG subclass and Fc glycan composition within ICs. Trivalent influenza virus vaccination elicited regulation of anti-hemagglutinin (HA) IgG subclass and Fc glycans, with abundance of sialylated Fc glycans (sFc) predicting quality of vaccine response. We show that sFcs drive BCR affinity selection by binding the Type-II FcR CD23, thus upregulating the inhibitory FcγRIIB on activated B cells. This elevates the threshold requirement for BCR signaling, resulting in B cell selection for higher affinity BCR. Immunization with sFc HA ICs elicited protective, high-affinity IgGs against the conserved stalk of the HA. These results reveal a novel, endogenous pathway for affinity maturation that can be exploited for eliciting high-affinity, broadly neutralizing antibodies through immunization with sialylated immune complexes.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Vacunas contra la Influenza/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Complejo Antígeno-Anticuerpo/química , Glicoproteínas Hemaglutininas del Virus de la Influenza/inmunología , Humanos , Fragmentos Fc de Inmunoglobulinas , Inmunoglobulina G/inmunología , Células Plasmáticas/inmunología , Receptores de Antígenos de Linfocitos B/química , Receptores Fc/metabolismo , Ácidos Siálicos/metabolismoRESUMEN
Broadly neutralizing antibodies (bNAbs) against HIV-1 provide both effective pre-exposure prophylaxis and treatment of HIV-1 infection in murine and nonhuman primate models, suggesting their potential use in humans. Although much is known about the role of variable domains in the neutralization breadth and potency of these bNAbs, the contribution of Fc domains to their activities is, by contrast, poorly characterized. Assessment of the in vivo activity of several bNAbs revealed that FcγR-mediated effector function contributes substantially to their capacity to block viral entry, suppress viremia, and confer therapeutic activity. Enhanced in vivo potency of anti-HIV-1 bNAbs was associated with preferential engagement of activating, but not inhibitory FcγRs, and Fc domain-engineered bNAb variants with selective binding capacity for activating FcγRs displayed augmented protective activity. These findings reveal key roles for Fc effector function in the in vivo activity of anti-HIV-1 bNAbs and provide strategies for generating bNAbs with improved efficacy.
Asunto(s)
Anticuerpos Neutralizantes/uso terapéutico , Anticuerpos Antivirales/uso terapéutico , Infecciones por VIH/tratamiento farmacológico , VIH-1 , Animales , Modelos Animales de Enfermedad , Humanos , Fragmentos Fc de Inmunoglobulinas/genética , Inmunoglobulina G/inmunología , Ratones , Primates , Receptores de IgG/metabolismo , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunologíaRESUMEN
Latent reservoirs of HIV-1-infected cells are refractory to antiretroviral therapies (ART) and remain the major barrier to curing HIV-1. Because latently infected cells are long-lived, immunologically invisible, and may undergo homeostatic proliferation, a "shock and kill" approach has been proposed to eradicate this reservoir by combining ART with inducers of viral transcription. However, all attempts to alter the HIV-1 reservoir in vivo have failed to date. Using humanized mice, we show that broadly neutralizing antibodies (bNAbs) can interfere with establishment of a silent reservoir by Fc-FcR-mediated mechanisms. In established infection, bNAbs or bNAbs plus single inducers are ineffective in preventing viral rebound. However, bNAbs plus a combination of inducers that act by independent mechanisms synergize to decrease the reservoir as measured by viral rebound. Thus, combinations of inducers and bNAbs constitute a therapeutic strategy that impacts the establishment and maintenance of the HIV-1 reservoir in humanized mice.
Asunto(s)
Anticuerpos Neutralizantes/administración & dosificación , Infecciones por VIH/inmunología , VIH-1/efectos de los fármacos , Transcripción Genética/efectos de los fármacos , Latencia del Virus/efectos de los fármacos , Animales , Fármacos Anti-VIH/uso terapéutico , Anticuerpos Neutralizantes/inmunología , Linfocitos T CD4-Positivos/inmunología , Antígeno CTLA-4/administración & dosificación , Infecciones por VIH/virología , VIH-1/genética , VIH-1/fisiología , Compuestos Heterocíclicos de 4 o más Anillos/administración & dosificación , Humanos , Ácidos Hidroxámicos/administración & dosificación , Fragmentos Fc de Inmunoglobulinas/inmunología , Ratones , Receptores Fc/inmunología , VorinostatRESUMEN
Monoclonal antibodies with neutralizing activity against SARS-CoV-2 have demonstrated clinical benefits in cases of mild-to-moderate SARS-CoV-2 infection, substantially reducing the risk for hospitalization and severe disease1-4. Treatment generally requires the administration of high doses of these monoclonal antibodies and has limited efficacy in preventing disease complications or mortality among hospitalized patients with COVID-195. Here we report the development and evaluation of anti-SARS-CoV-2 monoclonal antibodies with optimized Fc domains that show superior potency for prevention or treatment of COVID-19. Using several animal disease models of COVID-196,7, we demonstrate that selective engagement of activating Fcγ receptors results in improved efficacy in both preventing and treating disease-induced weight loss and mortality, significantly reducing the dose required to confer full protection against SARS-CoV-2 challenge and for treatment of pre-infected animals. Our results highlight the importance of Fcγ receptor pathways in driving antibody-mediated antiviral immunity and exclude the possibility of pathogenic or disease-enhancing effects of Fcγ receptor engagement of anti-SARS-CoV-2 antibodies upon infection. These findings have important implications for the development of Fc-engineered monoclonal antibodies with optimal Fc-effector function and improved clinical efficacy against COVID-19 disease.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Tratamiento Farmacológico de COVID-19 , COVID-19/inmunología , Fragmentos Fc de Inmunoglobulinas/inmunología , Fragmentos Fc de Inmunoglobulinas/uso terapéutico , SARS-CoV-2/efectos de los fármacos , SARS-CoV-2/inmunología , Animales , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/farmacología , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/inmunología , Anticuerpos Neutralizantes/farmacología , Anticuerpos Neutralizantes/uso terapéutico , Cricetinae , Modelos Animales de Enfermedad , Femenino , Humanos , Fragmentos Fc de Inmunoglobulinas/química , Fragmentos Fc de Inmunoglobulinas/farmacología , Inmunoglobulina G/química , Inmunoglobulina G/inmunología , Masculino , Ratones , Profilaxis Pre-Exposición , Receptores de IgG/química , Receptores de IgG/inmunología , Resultado del TratamientoRESUMEN
Antibodies produced in response to a foreign antigen are characterized by polyclonality, not only in the diverse epitopes to which their variable domains bind but also in the various effector molecules to which their constant regions (Fc domains) engage. Thus, the antibody's Fc domain mediates diverse effector activities by engaging two distinct classes of Fc receptors (type I and type II) on the basis of the two dominant conformational states that the Fc domain may adopt. These conformational states are regulated by the differences among antibody subclasses in their amino acid sequence and by the complex, biantennary Fc-associated N-linked glycan. Here we discuss the diverse downstream proinflammatory, anti-inflammatory and immunomodulatory consequences of the engagement of type I and type II Fc receptors in the context of infectious, autoimmune, and neoplastic disorders.
Asunto(s)
Inmunidad Adaptativa , Inmunidad Innata , Fragmentos Fc de Inmunoglobulinas/inmunología , Receptores de IgG/inmunología , Secuencia de Aminoácidos , Anticuerpos/inmunología , Presentación de Antígeno/inmunología , Enfermedades Autoinmunes/inmunología , Glicosilación , Humanos , Fragmentos Fc de Inmunoglobulinas/química , Fragmentos Fc de Inmunoglobulinas/clasificación , Inmunoglobulina G/inmunología , Neoplasias/inmunología , Conformación Proteica , Estructura Terciaria de Proteína , Receptores de IgG/química , Receptores de IgG/clasificación , VacunaciónRESUMEN
Through specific interactions with distinct types of Fcγ receptors (FcγRs), the Fc domain of immunoglobulin G (IgG) mediates a wide spectrum of immunological functions that influence both innate and adaptive responses. Recent studies indicate that IgG Fc-FcγR interactions are dynamically regulated during an immune response through the control of the Fc-associated glycan structure and Ig subclass composition on the one hand and selective FcγR expression on immune cells on the other, which together determine the capacity of IgG to interact in a cell-type-specific manner with specific members of the FcγR family. Here, we present a framework that synthesizes the current understanding of the contribution of FcγR pathways to the induction and regulation of antibody and T cell responses. Within this context, we discuss vaccination strategies to elicit broad and potent immune responses based on the immunomodulatory properties of Fc-FcγR interactions.
Asunto(s)
Fragmentos Fc de Inmunoglobulinas/metabolismo , Isotipos de Inmunoglobulinas/metabolismo , Receptores de IgG/metabolismo , Linfocitos T Reguladores/inmunología , Vacunas/inmunología , Animales , Humanos , Isotipos de Inmunoglobulinas/inmunología , Inmunomodulación , Receptores de IgG/inmunología , Transducción de Señal , VacunaciónRESUMEN
CD25 is expressed at high levels on regulatory T (Treg) cells and was initially proposed as a target for cancer immunotherapy. However, anti-CD25 antibodies have displayed limited activity against established tumors. We demonstrated that CD25 expression is largely restricted to tumor-infiltrating Treg cells in mice and humans. While existing anti-CD25 antibodies were observed to deplete Treg cells in the periphery, upregulation of the inhibitory Fc gamma receptor (FcγR) IIb at the tumor site prevented intra-tumoral Treg cell depletion, which may underlie the lack of anti-tumor activity previously observed in pre-clinical models. Use of an anti-CD25 antibody with enhanced binding to activating FcγRs led to effective depletion of tumor-infiltrating Treg cells, increased effector to Treg cell ratios, and improved control of established tumors. Combination with anti-programmed cell death protein-1 antibodies promoted complete tumor rejection, demonstrating the relevance of CD25 as a therapeutic target and promising substrate for future combination approaches in immune-oncology.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Fragmentos Fc de Inmunoglobulinas/inmunología , Subunidad alfa del Receptor de Interleucina-2/inmunología , Neoplasias/inmunología , Receptor de Muerte Celular Programada 1/inmunología , Linfocitos T Reguladores/inmunología , Animales , Anticuerpos Monoclonales/metabolismo , Anticuerpos Monoclonales/uso terapéutico , Línea Celular Tumoral , Citometría de Flujo , Humanos , Inmunoterapia/métodos , Células K562 , Estimación de Kaplan-Meier , Depleción Linfocítica , Ratones , Neoplasias/patología , Neoplasias/terapia , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Receptor de Muerte Celular Programada 1/metabolismo , Unión Proteica/inmunología , Receptores de IgG/inmunología , Receptores de IgG/metabolismo , Linfocitos T Reguladores/metabolismoRESUMEN
Antibodies against viral pathogens represent promising therapeutic agents for the control of infection, and their antiviral efficacy has been shown to require the coordinated function of both the Fab and Fc domains1. The Fc domain engages a wide spectrum of receptors on discrete cells of the immune system to trigger the clearance of viruses and subsequent killing of infected cells1-4. Here we report that Fc engineering of anti-influenza IgG monoclonal antibodies for selective binding to the activating Fcγ receptor FcγRIIa results in enhanced ability to prevent or treat lethal viral respiratory infection in mice, with increased maturation of dendritic cells and the induction of protective CD8+ T cell responses. These findings highlight the capacity for IgG antibodies to induce protective adaptive immunity to viral infection when they selectively activate a dendritic cell and T cell pathway, with important implications for the development of therapeutic antibodies with improved antiviral efficacy against viral respiratory pathogens.
Asunto(s)
Anticuerpos Antivirales/química , Anticuerpos Antivirales/inmunología , Linfocitos T CD8-positivos/inmunología , Fragmentos Fc de Inmunoglobulinas/química , Gripe Humana/inmunología , Orthomyxoviridae/inmunología , Animales , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Linfocitos T CD8-positivos/citología , Diferenciación Celular , Células Dendríticas/citología , Células Dendríticas/inmunología , Femenino , Glicoproteínas Hemaglutininas del Virus de la Influenza/inmunología , Humanos , Fragmentos Fc de Inmunoglobulinas/inmunología , Inmunoglobulina G/química , Inmunoglobulina G/inmunología , Gripe Humana/tratamiento farmacológico , Gripe Humana/mortalidad , Gripe Humana/prevención & control , Activación de Linfocitos , Ratones , Neuraminidasa/inmunología , Receptores de IgG/química , Receptores de IgG/inmunologíaRESUMEN
Antibody responses against highly conserved epitopes on the stalk domain of influenza virus hemagglutinin (HA) confer broad protection; however, such responses are limited. To effectively induce stalk-specific immunity against conserved HA epitopes, sequential immunization strategies have been developed based on chimeric HA (cHA) constructs featuring different head domains but the same stalk regions. Immunogenicity studies in small animal models, as well as in humans, revealed that cHA immunogens elicit stalk-specific IgG responses with broad specificity against heterologous influenza virus strains. However, the mechanisms by which these antibodies confer in vivo protection and the contribution of their Fc effector function remain unclear. To characterize the role of Fc-FcγR (Fcγ receptor) interactions to the in vivo protective activity of IgG antibodies elicited in participants in a phase I trial of a cHA vaccine candidate, we performed passive transfer studies of vaccine-elicited IgG antibodies in mice humanized for all classes of FcγRs, as well as in mice deficient for FcγRs. IgG antibodies elicited upon cHA vaccination completely protected FcγR humanized mice against lethal influenza virus challenge, while no protection was evident in FcγR-deficient mice, suggesting a major role for FcγR pathways in the protective function of vaccine-elicited IgG antibodies. These findings have important implications for influenza vaccine development, guiding the design of vaccination approaches with the capacity to elicit IgG responses with optimal Fc effector function.
Asunto(s)
Vacunas contra la Influenza , Gripe Humana , Infecciones por Orthomyxoviridae , Orthomyxoviridae , Humanos , Animales , Ratones , Hemaglutininas , Receptores de IgG/genética , Receptores de IgG/metabolismo , Anticuerpos Antivirales , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Orthomyxoviridae/metabolismo , Gripe Humana/prevención & control , Vacunación , Inmunoglobulina G , EpítoposRESUMEN
CD40 is a central costimulatory receptor implicated in productive antitumor immune responses across multiple cancers, including bladder cancer. Despite strong preclinical rationale, systemic administration of therapeutic agonistic antibodies targeting the CD40 pathway has demonstrated dose-limiting toxicities with minimal clinical activity, emphasizing an important need for optimized CD40-targeted approaches, including rational combination therapy strategies. Here, we describe a role for the endogenous IL-15 pathway in contributing to the therapeutic activity of CD40 agonism in orthotopic bladder tumors, with upregulation of transpresented IL-15/IL-15Rα surface complexes, particularly by cross-presenting conventional type 1 DCs (Dendritic Cells), and associated enrichment of activated CD8 T cells. In bladder cancer patient samples, we identify DCs as the primary source of IL-15, although they lack high levels of IL-15Rα at baseline. Using humanized immunocompetent orthotopic bladder tumor models, we demonstrate the ability to therapeutically augment this interaction through combined treatment with anti-CD40 agonist antibodies and exogenous IL-15, including the fully-human Fc-optimized antibody 2141-V11 currently in clinical development for the treatment of bladder cancer. Collectively, these data reveal an important role for IL-15 in mediating antitumor CD40 agonist responses in bladder cancer and provide key proof-of-concept for combined use of Fc-optimized anti-CD40 agonist antibodies and agents targeting the IL-15 pathway. These data support expansion of ongoing clinical studies evaluating anti-CD40 agonist antibodies and IL-15-based approaches to develop combinations of these promising therapeutics for the treatment of patients with bladder cancer.
Asunto(s)
Interleucina-15 , Neoplasias de la Vejiga Urinaria , Humanos , Neoplasias de la Vejiga Urinaria/tratamiento farmacológico , Vejiga Urinaria , Anticuerpos Monoclonales/farmacología , Anticuerpos Monoclonales/uso terapéutico , Terapia Combinada , Antígenos CD40 , Fragmentos Fc de InmunoglobulinasRESUMEN
Therapeutic human IgG antibodies are routinely tested in mouse models of oncologic, infectious, and autoimmune diseases. However, assessing the efficacy and safety of long-term administration of these agents has been limited by endogenous anti-human IgG immune responses that act to clear human IgG from serum and relevant tissues, thereby reducing their efficacy and contributing to immune complexmediated pathologies, confounding evaluation of potential toxicity. For this reason, human antibody treatment in mice is generally limited in duration and dosing, thus failing to recapitulate the potential clinical applications of these therapeutics. Here, we report the development of a mouse model that is tolerant of chronic human antibody administration. This model combines both a human IgG1 heavy chain knock-in and a full recapitulation of human Fc receptor (FcγR) expression, providing a unique platform for in vivo testing of human monoclonal antibodies with relevant receptors beyond the short term. Compared to controls, hIgG1 knock-in mice mount minimal anti-human IgG responses, allowing for the persistence of therapeutically active circulating human IgG even in the late stages of treatment in chronic models of immune thrombocytopenic purpura and metastatic melanoma.
Asunto(s)
Anticuerpos Monoclonales Humanizados/administración & dosificación , Inmunoglobulina G/inmunología , Animales , Anticuerpos Monoclonales Humanizados/uso terapéutico , Anticuerpos Monoclonales Humanizados/toxicidad , Formación de Anticuerpos/genética , Enfermedad Crónica , Humanos , Tolerancia Inmunológica , Inmunoglobulina G/administración & dosificación , Inmunoglobulina G/genética , Cadenas Pesadas de Inmunoglobulina/genética , Melanoma Experimental/inmunología , Melanoma Experimental/terapia , Ratones , Ratones Transgénicos , Modelos Animales , Púrpura Trombocitopénica Idiopática/inmunología , Púrpura Trombocitopénica Idiopática/terapiaRESUMEN
Protein glycosylation is a crucial mediator of biological functions and is tightly regulated in health and disease. However, interrogating complex protein glycoforms is challenging, as current lectin tools are limited by cross-reactivity while mass spectrometry typically requires biochemical purification and isolation of the target protein. Here, we describe a method to identify and characterize a class of nanobodies that can distinguish glycoforms without reactivity to off-target glycoproteins or glycans. We apply this technology to immunoglobulin G (IgG) Fc glycoforms and define nanobodies that specifically recognize either IgG lacking its core-fucose or IgG bearing terminal sialic acid residues. By adapting these tools to standard biochemical methods, we can clinically stratify dengue virus and SARS-CoV-2 infected individuals based on their IgG glycan profile, selectively disrupt IgG-Fcγ receptor binding both in vitro and in vivo, and interrogate the B cell receptor (BCR) glycan structure on living cells. Ultimately, we provide a strategy for the development of reagents to identify and manipulate IgG Fc glycoforms.
Asunto(s)
COVID-19 , Anticuerpos de Dominio Único , Humanos , Inmunoglobulina G/metabolismo , SARS-CoV-2 , Fragmentos Fc de Inmunoglobulinas/metabolismo , Polisacáridos/metabolismoRESUMEN
Understanding of how persistent viral infection impacts humoral immunity is incomplete. In this issue of Immunity, Wieland et al. (2015) and Yamada et al. (2015) find that high amounts of IgG-antigen complexes formed during chronic lymphocytic choriomeningitis infection can interfere with Fcγ-receptor-mediated effector activities, potentially contributing to immune dysfunction.
Asunto(s)
Anticuerpos Antivirales/inmunología , Complejo Antígeno-Anticuerpo/inmunología , Evasión Inmune/inmunología , Depleción Linfocítica , Coriomeningitis Linfocítica/inmunología , Receptores de IgG/antagonistas & inhibidores , Receptores de IgG/inmunología , AnimalesRESUMEN
Given the role of myeloid cells in T cell activation and in the antitumor response, targeting checkpoint molecules expressed on this population represents a promising strategy to augment antitumor immunity. However, myeloid checkpoints that can be effectively used as immunotherapy targets are still lacking. Here, we demonstrate the therapeutic potential of targeting the myeloid receptors Siglec-7 and Siglec-9 in vivo. By using a humanized immunocompetent murine model, we demonstrate that human Siglec-7 and Siglec-9, in addition to the murine homolog Siglec-E, inhibit the endogenous antitumor immune response, as well as the response to tumor-targeting and immune checkpoint inhibiting antibodies in vivo. The impact of these Siglecs on tumor progression is highly dependent on the anatomical distribution of the tumor and, as a consequence, the local tumor microenvironment, as tumors with a more immune-suppressive tumor microenvironment are less sensitive to Siglec perturbation. Finally, to assess the potential of these two receptors as targets for immunotherapy, we developed Fc engineered blocking antibodies to Siglec-7 and Siglec-9 and demonstrate that Siglec-7 and Siglec-9 blockade can significantly reduce tumor burden in vivo, demonstrating the therapeutic potential of targeting these two receptors.
Asunto(s)
Antígenos CD/metabolismo , Inhibidores de Puntos de Control Inmunológico/metabolismo , Inmunidad , Neoplasias/inmunología , Lectinas Similares a la Inmunoglobulina de Unión a Ácido Siálico/metabolismo , Animales , Anticuerpos/farmacología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Progresión de la Enfermedad , Humanos , Inmunidad/efectos de los fármacos , Ratones Endogámicos C57BL , Ratones Noqueados , Modelos Biológicos , Neoplasias/patología , Fenotipo , Microambiente TumoralRESUMEN
The IgG Fc domain has the capacity to interact with diverse types of receptors, including the neonatal Fc receptor (FcRn) and Fcγ receptors (FcγRs), which confer pleiotropic biological activities. Whereas FcRn regulates IgG epithelial transport and recycling, Fc effector activities, such as antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis, are mediated by FcγRs, which upon cross-linking transduce signals that modulate the function of effector leukocytes. Despite the well-defined and nonoverlapping functional properties of FcRn and FcγRs, recent studies have suggested that FcγRs mediate transplacental IgG transport, as certain Fc glycoforms were reported to be enriched in fetal circulation. To determine the contribution of FcγRs and FcRn to the maternal-fetal transport of IgG, we characterized the IgG Fc glycosylation in paired maternal-fetal samples from patient cohorts from Uganda and Nicaragua. No differences in IgG1 Fc glycan profiles and minimal differences in IgG2 Fc glycans were noted, whereas the presence or absence of galactose on the Fc glycan of IgG1 did not alter FcγRIIIa or FcRn binding, half-life, or their ability to deplete target cells in FcγR/FcRn humanized mice. Modeling maternal-fetal transport in FcγR/FcRn humanized mice confirmed that only FcRn contributed to transplacental transport of IgG; IgG selectively enhanced for FcRn binding resulted in enhanced accumulation of maternal antibody in the fetus. In contrast, enhancing FcγRIIIa binding did not result in enhanced maternal-fetal transport. These results argue against a role for FcγRs in IgG transplacental transport, suggesting Fc engineering of maternally administered antibody to enhance only FcRn binding as a means to improve maternal-fetal transport of IgG.
Asunto(s)
Sangre Fetal/inmunología , Antígenos de Histocompatibilidad Clase I/metabolismo , Inmunoglobulina G/metabolismo , Intercambio Materno-Fetal/inmunología , Circulación Placentaria/inmunología , Receptores Fc/metabolismo , Animales , Femenino , Antígenos de Histocompatibilidad Clase I/genética , Humanos , Inmunoglobulina G/inmunología , Ratones , Ratones Transgénicos , Embarazo , Ensayos Clínicos Controlados Aleatorios como Asunto , Receptores Fc/genética , Receptores de IgG/genética , Receptores de IgG/metabolismoRESUMEN
An essential mechanism for severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection begins with the viral spike protein binding to the human receptor protein angiotensin-converting enzyme II (ACE2). Here, we describe a stepwise engineering approach to generate a set of affinity optimized, enzymatically inactivated ACE2 variants that potently block SARS-CoV-2 infection of cells. These optimized receptor traps tightly bind the receptor binding domain (RBD) of the viral spike protein and prevent entry into host cells. We first computationally designed the ACE2-RBD interface using a two-stage flexible protein backbone design process that improved affinity for the RBD by up to 12-fold. These designed receptor variants were affinity matured an additional 14-fold by random mutagenesis and selection using yeast surface display. The highest-affinity variant contained seven amino acid changes and bound to the RBD 170-fold more tightly than wild-type ACE2. With the addition of the natural ACE2 collectrin domain and fusion to a human immunoglobulin crystallizable fragment (Fc) domain for increased stabilization and avidity, the most optimal ACE2 receptor traps neutralized SARS-CoV-2-pseudotyped lentivirus and authentic SARS-CoV-2 virus with half-maximal inhibitory concentrations (IC50s) in the 10- to 100-ng/mL range. Engineered ACE2 receptor traps offer a promising route to fighting infections by SARS-CoV-2 and other ACE2-using coronaviruses, with the key advantage that viral resistance would also likely impair viral entry. Moreover, such traps can be predesigned for viruses with known entry receptors for faster therapeutic response without the need for neutralizing antibodies isolated from convalescent patients.