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1.
Nature ; 577(7791): 543-548, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31915378

RESUMO

Although maternal antibodies protect newborn babies from infection1,2, little is known about how protective antibodies are induced without prior pathogen exposure. Here we show that neonatal mice that lack the capacity to produce IgG are protected from infection with the enteric pathogen enterotoxigenic Escherichia coli by maternal natural IgG antibodies against the maternal microbiota when antibodies are delivered either across the placenta or through breast milk. By challenging pups that were fostered by either maternal antibody-sufficient or antibody-deficient dams, we found that IgG derived from breast milk was crucial for protection against mucosal disease induced by enterotoxigenic E. coli. IgG also provides protection against systemic infection by E. coli. Pups used the neonatal Fc receptor to transfer IgG from milk into serum. The maternal commensal microbiota can induce antibodies that recognize antigens expressed by enterotoxigenic E. coli and other Enterobacteriaceae species. Induction of maternal antibodies against a commensal Pantoea species confers protection against enterotoxigenic E. coli in pups. This role of the microbiota in eliciting protective antibodies to a specific neonatal pathogen represents an important host defence mechanism against infection in neonates.


Assuntos
Anticorpos/imunologia , Escherichia coli Enterotoxigênica/imunologia , Infecções por Escherichia coli/imunologia , Infecções por Escherichia coli/prevenção & controle , Imunidade Materno-Adquirida/imunologia , Recém-Nascido/imunologia , Microbiota/imunologia , Leite Humano/imunologia , Animais , Anticorpos/sangue , Anticorpos/metabolismo , Aleitamento Materno , Reações Cruzadas/imunologia , Infecções por Escherichia coli/microbiologia , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Masculino , Camundongos , Mães , Pantoea/imunologia , Receptores Fc/imunologia , Receptores Fc/metabolismo , Simbiose/imunologia
2.
Viruses ; 12(1)2020 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-31936476

RESUMO

Porcine deltacoronavirus (PDCoV) is a porcine enteropathogenic coronavirus that causes watery diarrhea, vomiting, and frequently death in piglets, causing serious economic losses to the pig industry. The strain CHN-JS-2017 was isolated and identified by cytopathology, immunofluorescence assays, transmission electron microscopy, and sequence analysis. A nucleotide sequence alignment showed that the whole genome of CHN-JS-2017 is 97.4%-99.6% identical to other PDCoV strains. The pathogenicity of the CHN-JS-2017 strain was investigated in orally inoculated five-day-old piglets; the piglets developed acute, watery diarrhea, but all recovered and survived. CHN-JS-2017 infection-induced microscopic lesions were observed, and viral antigens were detected mainly by immunohistochemical staining in the small intestine. The neonatal Fc receptor (FcRn) and polymeric immunoglobulin receptor (pIgR) are crucial immunoglobulin (Ig) receptors for the transcytosis ofimmunoglobulin G (IgG), IgA, or IgM. Importantly, CHN-JS-2017 infected five-day-old piglets could significantly down-regulate the expression of FcRn, pIgR, and nuclear factor-kappa B (NF-κB)in the intestinal mucosa. Note that the level of FcRn mRNA in the intestinal mucosa of normal piglets is positively correlated with pIgR and NF-κB. At the same time, the expressions of FcRn, pIgR, and NF-κB mRNA are also positively correlated in infected piglets. These results may help explain the immunological and pathological changes associated with porcine deltacorononirus infection.


Assuntos
Infecções por Coronavirus/veterinária , Coronavirus/classificação , Antígenos de Histocompatibilidade Classe I/imunologia , Mucosa Intestinal/imunologia , Receptores Fc/imunologia , Receptores de Imunoglobulina Polimérica/imunologia , Doenças dos Suínos/virologia , Animais , Antígenos Virais/análise , Coronavirus/isolamento & purificação , Infecções por Coronavirus/imunologia , Diarreia/veterinária , Diarreia/virologia , Regulação da Expressão Gênica , Mucosa Intestinal/virologia , Intestino Delgado/imunologia , Intestino Delgado/virologia , NF-kappa B/imunologia , Filogenia , RNA Viral/análise , Alinhamento de Sequência , Análise de Sequência de DNA , Suínos , Doenças dos Suínos/imunologia , Eliminação de Partículas Virais
3.
PLoS Pathog ; 15(12): e1008064, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31841557

RESUMO

Broadly neutralizing antibodies (bNAbs) protect against HIV infection in non-human primates and their efficacy may be enhanced through interaction with Fc receptors on immune cells. Antibody isotype is a modulator of this binding with the IgG3 subclass mediating potent Fc effector function and is associated with HIV vaccine efficacy and HIV control. BNAb functions are typically assessed independently of the constant region with which they are naturally expressed. To examine the role of natural isotype in the context of a bNAb lineage we studied CAP256, an HIV-infected individual that mounted a potent V2-specific bNAb response. CAP256 expressed persistently high levels of plasma IgG3 which we found mediated both broad neutralizing activity and potent Fc function. Sequencing of germline DNA and the constant regions of V2-directed bNAbs from this donor revealed the expression of a novel IGHG3 allele as well as IGHG3*17, an allele that produces IgG3 antibodies with increased plasma half-life. Both allelic variants were used to generate CAP256-VRC26.25 and CAP256-VRC26.29 IgG3 bNAbs and these were compared to IgG1 versions. IgG3 variants were shown to have significantly higher phagocytosis and trogocytosis compared to IgG1 versions, which corresponded to increased affinity for FcγRIIa. Neutralization potency was also significantly higher for IgG3 bNAbs, particularly against viruses lacking the N160 glycan. By exchanging hinge regions between subclass variants, we showed that hinge length modulated both neutralization potency and Fc function. This study showed that co-operation between the variable and natural IgG3 constant regions enhanced the polyfunctionality of antibodies, indicating the value of leveraging genetic variation which could be exploited for passive immunity.


Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Amplamente Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Imunoglobulina G/imunologia , Isotipos de Imunoglobulinas/imunologia , Adulto , Feminino , Infecções por HIV/imunologia , Humanos , Receptores Fc/imunologia
4.
Autoimmun Rev ; 18(10): 102366, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31404703

RESUMO

In recent years, there has been a surge in the research and development of novel molecules as potential therapeutic alternatives to traditional treatments (such as intravenous immunoglobulins) for autoimmune disorders. The aim of this review is to describe different drug development strategies and evaluate how various molecules have performed in clinical trials to date. Broadly, three main approaches have been pursued. Recombinant fragment crystallisable (rFc) multimers primarily target Fcγ receptors (FcγRs) but may also affect the complement system. These include PF-06755347 (GL-2045), CSL730 (M230), CSL777 and Pan Fc Receptor Interacting Molecule (PRIM). Neonatal Fc receptor (FcRn)-targeting therapeutics block the FcRn receptor and are represented by candidate drugs such as the Fc fragment efgartigimod and the monoclonal antibodies rozanolixizumab (UCB7665), M281 and SYNT001. Finally, Fc and FcγR-targeting therapeutics, comprise molecules that target the Fc of IgG, such as the recombinant soluble FcγIIb receptor valziflocept (SM101/SHP652) and various monoclonal antibodies directed against the receptors. The developmental status of these three classes of molecules ranges from preclinical to ongoing phase 3 clinical studies. Efgartigimod and rozanolixizumab are the most advanced and have demonstrated encouraging results from phase 2 trials in immune thrombocytopenia and myasthenia gravis. Although initial results are promising, further long-term data and a better understanding of the unique mechanisms of action of the different molecules are needed. The efficacy, safety, convenience of administration, duration of effects, and cost will all contribute to determining which of the molecules will be successful in the clinic.


Assuntos
Doenças Autoimunes/terapia , Produtos Biológicos/uso terapêutico , Fragmentos Fc das Imunoglobulinas/imunologia , Terapia de Alvo Molecular , Receptores Fc/antagonistas & inibidores , Animais , Doenças Autoimunes/imunologia , Humanos , Receptores Fc/imunologia
5.
Blood ; 134(17): 1430-1440, 2019 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-31383641

RESUMO

Antibodies that bind CD47 on tumor cells and prevent interaction with SIRPα on phagocytes are active against multiple cancer types including T-cell lymphoma (TCL). Here we demonstrate that surface CD47 is heterogeneously expressed across primary TCLs, whereas major histocompatibility complex (MHC) class I, which can also suppress phagocytosis, is ubiquitous. Multiple monoclonal antibodies (mAbs) that block CD47-SIRPα interaction promoted phagocytosis of TCL cells, which was enhanced by cotreatment with antibodies targeting MHC class I. Expression levels of surface CD47 and genes that modulate CD47 pyroglutamation did not correlate with the extent of phagocytosis induced by CD47 blockade in TCL lines. In vivo treatment of multiple human TCL patient-derived xenografts or an immunocompetent murine TCL model with a short course of anti-CD47 mAb markedly reduced lymphoma burden and extended survival. Depletion of macrophages reduced efficacy in vivo, whereas depletion of neutrophils had no effect. F(ab')2-only fragments of anti-CD47 antibodies failed to induce phagocytosis by human macrophages, indicating a requirement for Fc-Fcγ receptor interactions. In contrast, F(ab')2-only fragments increased phagocytosis by murine macrophages independent of SLAMF7-Mac-1 interaction. Full-length anti-CD47 mAbs also induced phagocytosis by Fcγ receptor-deficient murine macrophages. An immunoglobulin G1 anti-CD47 mAb induced phagocytosis and natural killer cell-mediated cytotoxicity of TCL cells that was augmented by cotreatment with mogamulizumab, an anti-CCR4 mAb, or a mAb blocking MHC class I. These studies help explain the disparate activity of monotherapy with agents that block CD47 in murine models compared with patients. They also have direct translational implications for the deployment of anti-CD47 mAbs alone or in combination.


Assuntos
Antígenos de Diferenciação/imunologia , Antineoplásicos Imunológicos/farmacologia , Antígeno CD47/imunologia , Linfoma de Células T/tratamento farmacológico , Receptores de IgG/imunologia , Receptores Imunológicos/imunologia , Animais , Antineoplásicos Imunológicos/uso terapêutico , Antígeno CD47/antagonistas & inibidores , Linhagem Celular Tumoral , Humanos , Linfoma de Células T/imunologia , Linfoma de Células T/patologia , Camundongos , Receptores Fc/imunologia
6.
Nat Commun ; 10(1): 3020, 2019 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-31289263

RESUMO

Human cytomegalovirus (HCMV) can persistently infect humans, but how HCMV avoids humoral immunity is not clear. The neonatal Fc receptor (FcRn) controls IgG transport from the mother to the fetus and prolongs IgG half-life. Here we show that US11 inhibits the assembly of FcRn with ß2m and retains FcRn in the endoplasmic reticulum (ER), consequently blocking FcRn trafficking to the endosome. Furthermore, US11 recruits the ubiquitin enzymes Derlin-1, TMEM129 and UbE2J2 to engage FcRn, consequently initiating the dislocation of FcRn from the ER to the cytosol and facilitating its degradation. Importantly, US11 inhibits IgG-FcRn binding, resulting in a reduction of IgG transcytosis across intestinal or placental epithelial cells and IgG degradation in endothelial cells. Hence, these results identify the mechanism by which HCMV infection exploits an ER-associated degradation pathway through US11 to disable FcRn functions. These results have implications for vaccine development and immune surveillance.


Assuntos
Infecções por Citomegalovirus/imunologia , Citomegalovirus/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Evasão da Resposta Imune , Imunidade Humoral , Proteínas de Ligação a RNA/metabolismo , Receptores Fc/metabolismo , Proteínas Virais/metabolismo , Linhagem Celular , Citomegalovirus/patogenicidade , Infecções por Citomegalovirus/virologia , Degradação Associada com o Retículo Endoplasmático/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutagênese Sítio-Dirigida , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Receptores Fc/imunologia , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Virais/genética , Proteínas Virais/imunologia
7.
Vet Immunol Immunopathol ; 213: 109889, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31307671

RESUMO

Blocking immunoglobulin G (IgG) binding receptors on leukocytes is an established and highly recommended preventive procedure for immunological assays. Failing to prevent such nonspecific binding can lead to erroneous results. Several studies testing different blocking reagents have been performed in murine or human cells, however, there are no specific studies on bovine cells. Our study aimed to investigate the efficiency of blocking reagents to inhibit the nonspecific binding of mouse monoclonal antibodies (mAbs) to bovine peripheral blood cells. We observed nonspecific interactions of IgG2a and IgG2b negative isotypes with bovine leukocytes, but not IgG1. We found that these nonspecific bindings could be eliminated by blocking with purified mouse IgG, whereas little or no blocking effect was observed when bovine serum or Mouse Seroblock FcR were applied. Moreover, in the absence of an efficient blocking reagent, the percentage of CD335 positive cells was significantly higher than in the group previously blocked with mouse IgG. Based on these results, and due to the lack of specific commercial blocking reagents for bovine cells, our recommendation is to use purified mouse IgG as a blocking reagent for immune assays targeting bovine leukocytes in order to enhance the accuracy of the results.


Assuntos
Anticorpos Monoclonais/imunologia , Imunofenotipagem/métodos , Leucócitos Mononucleares/imunologia , Receptores Fc/imunologia , Erro Experimental , Animais , Bovinos , Epitopos/imunologia , Citometria de Fluxo , Imunoglobulina G/imunologia , Imunoglobulina G/isolamento & purificação , Imunofenotipagem/normas , Camundongos , Ligação Proteica
8.
MAbs ; 11(6): 996-1011, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31156033

RESUMO

Agonism of members of the tumor necrosis factor receptor superfamily (TNFRSF) with monoclonal antibodies is of high therapeutic interest due to their role in immune regulation and cell proliferation. A major hurdle for pharmacologic activation of this receptor class is the requirement for high-order clustering, a mechanism that imposes a reliance in vivo on Fc receptor-mediated crosslinking. This extrinsic dependence represents a potential limitation of virtually the entire pipeline of agonist TNFRSF antibody drugs, of which none have thus far been approved or reached late-stage clinical trials. We show that tetravalent biepitopic targeting enables robust intrinsic antibody agonism for two members of this family, OX40 and DR5, that is superior to extrinsically crosslinked native parental antibodies. Tetravalent biepitopic anti-OX40 engagement co-stimulated OX40low cells, obviated the requirement for CD28 co-signal for T cell activation, and enabled superior pharmacodynamic activity relative to native IgG in a murine vaccination model. This work establishes a proof of concept for an engineering approach that addresses a major gap for the therapeutic activation of this important receptor class.


Assuntos
Anticorpos Monoclonais/imunologia , Capeamento Imunológico , Ligante OX40/agonistas , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/agonistas , Transdução de Sinais/imunologia , Linfócitos T/imunologia , Animais , Antígenos CD28/imunologia , Células CHO , Cricetulus , Humanos , Células Jurkat , Camundongos , Camundongos SCID , Camundongos Transgênicos , Ligante OX40/imunologia , Receptores Fc/imunologia , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/imunologia , Linfócitos T/citologia
9.
PLoS Pathog ; 15(6): e1007797, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31220194

RESUMO

During viral infection, tight regulation of CD8+ T-cell functions determines the outcome of the disease. Recently, others and we determined that the natural killer (NK) cells kill hyperproliferative CD8+ T cells in the context of viral infection, but molecules that are involved in shaping the regulatory capability of NK cells remain virtually unknown. Here we used mice lacking the Fc-receptor common gamma chain (FcRγ, FcεRIγ, Fcer1g-/- mice) to determine the role of Fc-receptor and NK-receptor signaling in the process of CD8+ T-cell regulation. We found that the lack of FcRγ on NK cells limits their ability to restrain virus-specific CD8+ T cells and that the lack of FcRγ in Fcer1g-/- mice leads to enhanced CD8+ T-cell responses and rapid control of the chronic docile strain of the lymphocytic choriomeningitis virus (LCMV). Mechanistically, FcRγ stabilized the expression of NKp46 but not that of other killer cell-activating receptors on NK cells. Although FcRγ did not influence the development or activation of NK cell during LCMV infection, it specifically limited their ability to modulate CD8+ T-cell functions. In conclusion, we determined that FcRγ plays an important role in regulating CD8+ T-cell functions during chronic LCMV infection.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Ativação Linfocitária , Coriomeningite Linfocítica/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Receptores Fc/imunologia , Doença Aguda , Animais , Antígenos Ly/genética , Antígenos Ly/imunologia , Linfócitos T CD8-Positivos/patologia , Doença Crônica , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/patologia , Coriomeningite Linfocítica/genética , Coriomeningite Linfocítica/patologia , Camundongos , Camundongos Knockout , Receptor 1 Desencadeador da Citotoxicidade Natural/genética , Receptor 1 Desencadeador da Citotoxicidade Natural/imunologia , Receptores Fc/genética
10.
PLoS One ; 14(5): e0217061, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31120944

RESUMO

In this study we compared the pharmacokinetic profile of four unrelated antibodies, which do not bind to mammalian antigens, in IgG1 and IgG2 frameworks in both rats and non-human primates (NHP). This allowed for extensive cross comparison of the impact of antibody isotype, complementarity determining regions (CDR) and model species on pharmacokinetics without the confounding influence of antigen binding in the hosts. While antibody isotype had no significant impact on the pharmacokinetics, the CDRs do alter the profile, and there is an inverse correlation between the neonatal Fc receptor (FcRn) affinity and pharmacokinetic performance. Faster clearance rates were also associated with higher isoelectric points; however, although this panel of antibodies all possess basic isoelectric points, ranging from 8.44 to 9.18, they also have exceptional in vivo half-lives, averaging 369 hours, and low clearance rates, averaging 0.18 ml/h/kg in NHPs. This pattern of pharmacokinetic characteristics was conserved between rats and NHPs.


Assuntos
Anticorpos/metabolismo , Imunoglobulina G/metabolismo , Animais , Anticorpos Monoclonais/imunologia , Células CHO , Regiões Determinantes de Complementaridade/imunologia , Cricetinae , Cricetulus , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Masculino , Camundongos , Farmacocinética , Primatas/imunologia , Ligação Proteica , Ratos , Ratos Sprague-Dawley , Receptores Fc/imunologia
11.
Am J Health Syst Pharm ; 76(11): 789-794, 2019 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-30951590

RESUMO

PURPOSE: The pharmacology, pharmacokinetics, efficacy, safety, dosing and administration, and place in therapy of fostamatinib, a novel spleen tyrosine kinase inhibitor for the treatment of adult immune thrombocytopenia that has had an insufficient response to a previous treatment are summarized. SUMMARY: Fostamatinib is an oral inhibitor of spleen tyrosine kinase that is expressed on hematopoietic cells and plays a key role in the accelerated destruction of platelets through Fc-receptor activation. Fostamatinib is indicated for the treatment of adults with immune thrombocytopenia that has had an insufficient response to a previous treatment. In 2 parallel, identically designed, placebo-controlled Phase III trials, patients with persistent and chronic immune thrombocytopenia treated with fostamatinib demonstrated clinically meaningful responses in platelet counts with lower rates of moderate and severe bleeding-related adverse events. Overall, fostamatinib therapy is generally well tolerated; the most common adverse events reported in clinical trials were diarrhea, nausea, hypertension, liver function test elevations, and infection. Being primarily metabolized through the CYP3A4 pathway, fostamatinib is subject to drug-drug interactions and concomitant administration with strong CYP3A4 inhibitors or inducers can affect fostamatinib exposure. CONCLUSION: Fostamatinib is a first-in-class spleen tyrosine kinase inhibitor approved for the treatment of adults with immune thrombocytopenia that has had an insufficient response to a previous treatment.


Assuntos
Plaquetas/efeitos dos fármacos , Oxazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Púrpura Trombocitopênica Idiopática/tratamento farmacológico , Piridinas/farmacologia , Quinase Syk/antagonistas & inibidores , Administração Oral , Plaquetas/imunologia , Ensaios Clínicos Fase III como Assunto , Relação Dose-Resposta a Droga , Humanos , Oxazinas/uso terapêutico , Contagem de Plaquetas , Inibidores de Proteínas Quinases/uso terapêutico , Púrpura Trombocitopênica Idiopática/imunologia , Piridinas/uso terapêutico , Receptores Fc/imunologia , Receptores Fc/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/imunologia , Quinase Syk/metabolismo , Resultado do Tratamento
12.
MAbs ; 11(5): 942-955, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30982394

RESUMO

A cell-based assay employing Madin-Darby canine kidney cells stably expressing human neonatal Fc receptor (FcRn) heavy chain and ß2-microglobulin genes was developed to measure transcytosis of monoclonal antibodies (mAbs) under conditions relevant to the FcRn-mediated immunoglobulin G (IgG) salvage pathway. The FcRn-dependent transcytosis assay is modeled to reflect combined effects of nonspecific interactions between mAbs and cells, cellular uptake via pinocytosis, pH-dependent interactions with FcRn, and dynamics of intracellular trafficking and sorting mechanisms. Evaluation of 53 mAbs, including 30 marketed mAb drugs, revealed a notable correlation between the transcytosis readouts and clearance in humans. FcRn was required to promote efficient transcytosis of mAbs and contributed directly to the observed correlation. Furthermore, the transcytosis assay correctly predicted rank order of clearance of glycosylation and Fv charge variants of Fc-containing proteins. These results strongly support the utility of this assay as a cost-effective and animal-sparing screening tool for evaluation of mAb-based drug candidates during lead selection, optimization, and process development for desired pharmacokinetic properties.


Assuntos
Anticorpos Monoclonais Humanizados/farmacocinética , Antígenos de Histocompatibilidade Classe I/imunologia , Receptores Fc/imunologia , Transcitose/imunologia , Animais , Anticorpos Monoclonais Humanizados/imunologia , Anticorpos Monoclonais Humanizados/metabolismo , Bioensaio/métodos , Cães , Glicosilação , Humanos , Imunoglobulina G/metabolismo , Células Madin Darby de Rim Canino , Camundongos
13.
Am J Obstet Gynecol ; 220(5): 498.e1-498.e9, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30849355

RESUMO

BACKGROUND: The transfer of pathogenic immunoglobulin G antibodies from mother to fetus is a critical step in the pathophysiology of alloimmune and autoimmune diseases of the fetus and neonate. Immunoglobulin G transfer across the human placenta to the fetus is mediated by the neonatal Fc receptor, and blockade of the neonatal Fc receptor may provide a therapeutic strategy to prevent or minimize pathological events associated with immune-mediated diseases of pregnancy. M281 is a fully human, aglycosylated monoclonal immunoglobulin G1 antineonatal Fc receptor antibody that has been shown to block the neonatal Fc receptor with high affinity in nonclinical studies and in a phase 1 study in healthy volunteers. OBJECTIVE: The objective of the study was to determine the transplacental transfer of M281 and its potential to inhibit transfer of immunoglobulin G from maternal to fetal circulation. STUDY DESIGN: To determine the concentration of M281 required for rapid cellular uptake and complete saturation of the neonatal Fc receptor in placental trophoblasts, primary human villous trophoblasts were incubated with various concentrations of M281 in a receptor occupancy assay. The placental transfer of M281, immunoglobulin G, and immunoglobulin G in the presence of M281 was studied using the dually perfused human placental lobule model. Immunoglobulin G transfer was established using a representative immunoglobulin G molecule, adalimumab, a human immunoglobulin G1 monoclonal antibody, at a concentration of 270 µg/mL. Inhibition of immunoglobulin G transfer by M281 was determined by cotransfusing 270 µg/mL of adalimumab with 10 µg/mL or 300 µg/mL of M281. Concentrations of adalimumab and M281 in sample aliquots from maternal and fetal circuits were analyzed using a sandwich enzyme-linked immunosorbent assay and Meso Scale Discovery assay, respectively. RESULTS: In primary human villous trophoblasts, the saturation of the neonatal Fc receptor by M281 was observed within 30-60 minutes at 0.15-5.0 µg/mL, suggesting rapid blockade of neonatal Fc receptor in placental cells. The transfer rate of adalimumab (0.23% ± 0.21%) across dually perfused human placental lobule was significantly decreased by 10 µg/mL and 300 µg/mL of M281 to 0.07 ± 0.01% and 0.06 ± 0.01%, respectively. Furthermore, the transfer rate of M281 was 0.002% ± 0.02%, approximately 100-fold lower than that of adalimumab. CONCLUSION: The significant inhibition of immunoglobulin G transfer across the human placental lobule by M281 and the minimal transfer of M281 supports the development of M281 as a novel agent for the treatment of fetal and neonatal diseases caused by transplacental transfer of alloimmune and autoimmune pathogenic immunoglobulin G antibodies.


Assuntos
Anticorpos Monoclonais/farmacologia , Imunoglobulina G/metabolismo , Troca Materno-Fetal/imunologia , Placenta/imunologia , Receptores Fc/imunologia , Adalimumab , Transporte Biológico , Feminino , Humanos , Imunoglobulina G/imunologia , Modelos Biológicos , Placenta/metabolismo , Gravidez , Trofoblastos/imunologia
14.
Curr Top Microbiol Immunol ; 423: 1-11, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30739161

RESUMO

Immunoglobulins (Ig), a critical component of the adaptive immune system, are present in all jawed vertebrates and through sophisticated diversification mechanisms are able to recognize antigens of almost infinite diversity. During mammalian evolution, IgG has emerged as the predominant Ig isotype that is elicited upon antigenic challenge, representing the most abundant isotype present in circulation. Along with the IgG molecule, a family of specialized receptors has evolved in mammalian species that specifically recognize the Fc domain of IgG. These receptors, termed Fcγ receptors (FcγRs), are expressed on the surface of effector leukocytes and upon crosslinking by the IgG Fc domain mediate diverse immunomodulatory processes with profound impact on several aspects of innate and adaptive immunity. FcγRs share a high degree of sequence homology among mammalian species and the ancestral locus, where the genes that encode for FcγRs are mapped, can be traced back early in mammalian evolution. FcγRs also share a number of common structural and functional properties among mammalian species and utilize highly conserved motifs for transducing signals upon engagement. Despite the high homology of FcγRs in diverse mammalian species, human FcγRs exhibit unique features relating to the gene organization, expression pattern in the various leukocyte populations, as well as affinity for human IgGs. Such inter-species differences in FcγRs biology between humans and other mammalian species represents a major limitation for the interpretation of in vivo studies on human IgG function using conventional animal models.


Assuntos
Receptores Fc/imunologia , Receptores de IgG/imunologia , Animais , Humanos , Imunoglobulina G/química , Imunoglobulina G/imunologia , Modelos Animais
15.
Curr Top Microbiol Immunol ; 423: 119-150, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30790076

RESUMO

Antibodies are the key effector molecules of the humoral immune system providing long-term protective immunity against a wide range of pathogens and regulating immune responses. Traditionally, antibody-mediated protection against microbes was thought to be mainly a result of neutralizing Fab-antigen interaction; however, an increasing number of studies show the importance of proper FcR engagement for the protective capacity of antimicrobial antibodies. In this chapter, we review FcR-mediated effector functions contributing to antimicrobial protection in a direct and indirect manner. Furthermore, we highlight recent findings about the important role of Fc-FcR interactions for antimicrobial protection in vivo and provide examples demonstrating the crucial role of proper FcR engagement for antibody-mediated protection against viruses, bacteria, fungi, and parasites.


Assuntos
Anti-Infecciosos/imunologia , Receptores Fc/imunologia , Antibacterianos/imunologia , Anticorpos/imunologia , Humanos , /parasitologia , /virologia
16.
Curr Top Microbiol Immunol ; 423: 13-34, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30790079

RESUMO

Monoclonal antibodies can mediate antitumor activity by multiple mechanisms. They can bind directly to tumor receptors resulting in tumor cell death, or can bind to soluble growth factors, angiogenic factors, or their cognate receptors blocking signals required for tumor cell growth or survival. Monoclonal antibodies, upon binding to tumor cell, can also engage the host's immune system to mediate immune-mediated destruction of the tumor. The Fc portion of the antibody is essential in engaging the host immune system by fixing complement resulting in complement-mediated cytotoxicity (CDC) of the tumor, or by engaging Fc receptors for IgG (FcγR) expressed by leukocytes leading to antibody-dependent cellular cytotoxicity (ADCC) or antibody-dependent cellular phagocytosis (ADCP) of tumor cells. Antibodies whose Fc portion preferentially engage activating FcγRs have shown greater inhibition of tumor growth and metastasis. Monoclonal antibodies can also stimulate the immune system by binding to targets expressed on immune cells. These antibodies may stimulate antitumor immunity by antagonizing a negative regulatory signal, agonizing a costimulatory signal, or depleting immune cells that are inhibitory. The importance of Fc:FcγR interactions in antitumor therapy for each of these mechanisms have been demonstrated in both mouse models and clinical trials and will be the focus of this chapter.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/uso terapêutico , Neoplasias/tratamento farmacológico , Neoplasias/imunologia , Receptores Fc/imunologia , Receptores de IgG/imunologia , Animais , Citotoxicidade Celular Dependente de Anticorpos/imunologia , Humanos , Neoplasias/patologia
17.
Cell Mol Life Sci ; 76(6): 1041-1055, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30498997

RESUMO

The prevailing concept regarding the immunological function of immunoglobulin A (IgA) is that it binds to and neutralizes pathogens to prevent infection at mucosal sites of the body. However, recently, it has become clear that in humans IgA is also able to actively contribute to the initiation of inflammation, both at mucosal and non-mucosal sites. This additional function of IgA is initiated by the formation of immune complexes, which trigger Fc alpha Receptor I (FcαRI) to synergize with various other receptors to amplify inflammatory responses. Recent findings have demonstrated that co-stimulation of FcαRI strongly affects pro-inflammatory cytokine production by various myeloid cells, including different dendritic cell subsets, macrophages, monocytes, and Kupffer cells. FcαRI-induced inflammation plays a crucial role in orchestrating human host defense against pathogens, as well as the generation of tissue-specific immunity. In addition, FcαRI-induced inflammation is suggested to be involved in the pathogenesis of various chronic inflammatory disorders, including inflammatory bowel disease, celiac disease, and rheumatoid arthritis. Combined, IgA-induced inflammation may be used to either promote inflammatory responses, e.g. in the context of cancer therapy, but may also provide new therapeutic targets to counteract chronic inflammation in the context of various chronic inflammatory disorders.


Assuntos
Antígenos/imunologia , Imunoglobulina A/imunologia , Inflamação/imunologia , Membrana Mucosa/imunologia , Antígenos/metabolismo , Antígenos CD/imunologia , Antígenos CD/metabolismo , Citocinas/imunologia , Citocinas/metabolismo , Humanos , Imunoglobulina A/metabolismo , Modelos Imunológicos , Membrana Mucosa/metabolismo , Células Mieloides/imunologia , Células Mieloides/metabolismo , Ligação Proteica , Receptores Fc/imunologia , Receptores Fc/metabolismo
18.
J Pathol ; 247(3): 371-380, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30426510

RESUMO

Immunoglobulins (Igs) consist of two antigen-binding regions (Fab) and one constant region (Fc). Protein A and protein G are bacterial proteins used for the purification of IgG by virtue of their high affinities for the Fc fragment. Rheumatoid factors are autoantibodies against IgG Fc fragments, which are present in the body under physiological conditions. Little is known about the influence of Fc-binding proteins on the pathogenicity of antibody-induced autoimmune diseases. Pemphigoid diseases are a group of autoimmune subepidermal blistering disorders that includes bullous pemphigoid and mucous membrane pemphigoid. IgGs targeting the non-collagenous NC16A domain of the 180-kDa bullous pemphigoid antigen (BP180) are known to induce skin fragility in mice and the depletion of BP180 in keratinocytes. In this study, mAb against NC16A in combination with Fc-binding proteins was found to enhance BP180 depletion. Although mAb against the C-terminus of BP180 does not show pathogenicity in vivo or in vitro, mAb treatment with Fc-binding proteins clearly induced skin fragility in mice and BP180 depletion in keratinocytes. Anti-BP180 mAbs and Fc-binding proteins were colocalized in the cytoplasm and at the basement membrane zone. Cell adhesion strengths were decreased in parallel with BP180 amounts. Clinically, bullous pemphigoid patients had higher rheumatoid factor titers than controls. Anti-BP180 mAb in combination with high-titer rheumatoid factor serum was found to enhance BP180 depletion. Furthermore, saliva from mucous membrane pemphigoid patients contained larger quantities of bacteria and Fc-binding proteins than controls. Our results suggest that Fc-binding proteins (rheumatoid factor or protein G) may enhance the pathogenicity of autoantibodies in pemphigoid diseases. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Assuntos
Autoantígenos/metabolismo , Doenças Autoimunes/imunologia , Colágenos não Fibrilares/metabolismo , Penfigoide Bolhoso/imunologia , Receptores Fc/imunologia , Animais , Anticorpos Monoclonais/imunologia , Autoanticorpos/imunologia , Doenças Autoimunes/patologia , Proteínas de Transporte/imunologia , Células Cultivadas , Feminino , Humanos , Imunoglobulina G/imunologia , Queratinócitos/metabolismo , Masculino , Camundongos Transgênicos , Penfigoide Mucomembranoso Benigno/imunologia , Penfigoide Mucomembranoso Benigno/patologia , Penfigoide Bolhoso/patologia , Fator Reumatoide/sangue , Saliva/imunologia
19.
Int Immunopharmacol ; 66: 362-365, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30529500

RESUMO

Primary immune thrombocytopenia (ITP) is an autoimmune disease characterized by pathogenic immunoglobulin G (IgG) autoantibodies that bind to platelets, causing their phagocytic removal and leading to reductions in platelet number. The neonatal Fc receptor (FcRn) selectively salvages and recycles IgG, including pathogenic IgG, thereby extending the half-life of IgG in plasma. Two anti-mouse FcRn monoclonal antibodies (mAb) (4470 and 4464) were generated to evaluate the effect of inhibiting IgG recycling. Statistically significant reductions in plasma IgG concentration were observed upon administration of 4470 (10, 30 and 100 mg/kg) in wild-type mice. In a passive mouse model of ITP, 4464 alleviated the reduction in platelet number and/or preserved newly produced platelets when dosed prophylactically as well as in a therapeutic dosing regimen once platelet numbers had already been reduced. These results support the investigation of anti-FcRn therapy as a potential treatment for ITP.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Plaquetas/imunologia , Imunoglobulina G/sangue , Imunoglobulinas Intravenosas/uso terapêutico , Imunoterapia/métodos , Anticorpos de Cadeia Única/uso terapêutico , Trombocitopenia/terapia , Animais , Anticorpos Monoclonais/genética , Autoanticorpos/metabolismo , Linhagem Celular , Modelos Animais de Doenças , Feminino , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Imunidade Humoral , Camundongos , Camundongos Endogâmicos C57BL , Contagem de Plaquetas , Receptores Fc/imunologia , Anticorpos de Cadeia Única/genética , Trombocitopenia/imunologia
20.
Int Immunol ; 31(2): 81-90, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30535055

RESUMO

The development of a universal influenza vaccine that can provide a robust and long-lasting protection against a broader range of influenza virus strains is a global public health priority. One approach to improve vaccine efficacy is to use an adjuvant to boost immune responses to the target antigens; nevertheless, the role of adjuvants in the context of influenza vaccines is not fully understood. We have previously developed the K3-schizophyllan (SPG) adjuvant, which is composed of nanoparticulated oligodeoxynucleotides K3, a TLR9 agonist, with SPG, a non-agonistic ß-glucan ligand of Dectin-1. In this study, K3-SPG given with conventional influenza hemagglutinin (HA) split vaccine (K3-SPG HA) conferred protection against antigenically mismatched heterologous virus challenge. While K3-SPG HA elicited robust cross-reactive HA-specific IgG2c and CD8 T-cell responses, CD8 T-cell depletion had no impact on this cross-protection. In contrast, K3-SPG HA was not able to confer protection against heterologous virus challenge in FcRγ-deficient mice. Our results indicated that FcγR-mediated antibody responses induced by the HA antigen and K3-SPG adjuvant were important for potent protection against antigenically mismatched influenza virus infection. Thus, we demonstrated that the K3-SPG-adjuvanted vaccine strategy broadens protective immunity against influenza and provides a basis for the development of next-generation influenza vaccines.


Assuntos
Hemaglutininas Virais/imunologia , Vacinas contra Influenza/imunologia , Influenza Humana/imunologia , Nanopartículas/química , Infecções por Orthomyxoviridae/imunologia , Receptores Fc/imunologia , Animais , Feminino , Humanos , Vacinas contra Influenza/química , Camundongos , Camundongos Endogâmicos C57BL , Receptor Toll-Like 9/agonistas , Receptor Toll-Like 9/imunologia
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