abstract: Antibodies are naturally occurring proteins that protect a host during infection through direct neutralization and/or recruitment of the innate immune system. Unfortunately, in some infections, antibodies present unique hurdles that must be overcome for a safer and more efficacious antibody-based therapeutic (e.g., antibody dependent viral enhancement (ADE) and inflammatory pathology). This dissertation describes the utilization of plant expression systems to produce N-glycan specific antibody-based therapeutics for Dengue Virus (DENV) and Chikungunya Virus (CHIKV). The Fc region of an antibody interacts with Fcγ Receptors (FcγRs) on immune cells and components of the innate immune system. Each class of immune cells has a distinct action of neutralization (e.g., antibody dependent cell-mediated cytotoxicity (ADCC) and antibody dependent cell-mediated phagocytosis (ADCP)). Therefore, structural alteration of the Fc region results in novel immune pathways of protection. One approach is to modulate the N-glycosylation in the Fc region of the antibody. Of scientific significance, is the plant’s capacity to express human antibodies with homogenous plant and humanized N-glycosylation (WT and GnGn, respectively). This allows to study how specific glycovariants interact with other components of the immune system to clear an infection, producing a tailor-made antibody for distinct diseases. In the first section, plant-produced glycovariants were explored for reduced interactions with specific FcγRs for the overall reduction in ADE for DENV infections. The results demonstrate a reduction in ADE of our plant-produced monoclonal antibodies in in vitro experiments, which led to a greater survival in vivo of immunodeficient mice challenged with lethal doses of DENV and a sub-lethal dose of DENV in ADE conditions. In the second section, plant-produced glycovariants were explored for increased interaction with specific FcγRs to improve ADCC in the treatment of the highly inflammatory CHIKV. The results demonstrate an increase ADCC activity in in vitro experiments and a reduction in CHIKV-associated inflammation in in vivo mouse models. Overall, the significance of this dissertation is that it can provide a treatment for DENV and CHIKV; but equally importantly, give insight to the role of N-glycosylation in antibody effector functions, which has a broader implication for therapeutic development for other viral infections. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2019

Antibodies are the defining characteristic of the humoral immune response. Their functions are diverse, including direct neutralization of pathogens and recruitment of other immune molecules or cells. While most successful vaccines induce protective neutralizing antibody responses, effective vaccine-elicited neutralizing antibodies against some pathogens, including HIV, HCV, malaria, and TB, remain elusive. Thus, researchers have begun to focus on how vaccines can elicit strong non-neutralizing antibody functions, including recruitment of innate immune factors for antibody-dependent cellular cytotoxicity, complement deposition, and anti\-body-dependent phagocytosis. The antibody's constant region (Fc) mediates most effector functions through isotype and subclass selection or alteration of the structure of the Fc-attached N-glycan, which controls function with exquisite specificity. Glycan modifications are naturally induced during inflammatory conditions such as autoimmune disease and natural infection however, the specific signals that regulate Fc-glycosylation remain unknown. This dissertation sought to understand how antibody glycosylation is regulated and how it can be programmed through vaccination. To do this, we first developed a technique to analyze antibody glycan structures both of bulk Fc and antigen-specific antibodies. Using this technique, we observed significant modulation of antibody glycans during viral infection as well as in vaccine-elicited antibodies. To identify specific signals important for altering the antibody glycan, we transcriptionally profiled stimulated B cells and identified a set of innate and adaptive stimuli that regulate the genes responsible for antibody glycosylation. The results described in this dissertation begin to define the specific mechanism(s) by which infection and vaccination modulate antibody glycosylation to elicit functional antibodies that can ultimately provide effective and sustained protection from infection.

No description available.

No description available.

Thy-1 is a glycosylphosphatidylinositol-anchored protein that is expressed on murine T lymphocytes and is involved in T cell-mediated immune responses. In the presence of costimulatory signals, monoclonal antibody (mAb)-induced signaling through Thy-1 is associated with hallmarks of T cell activation, including IL-2 production and T cell proliferation. Thy-1-induced signaling promotes cytotoxic effector molecule expression, but is unable to trigger delivery of the lethal hit to target cells, suggesting that Thy-1 provides an incomplete T cell receptor (TcR)-like signal. However, the effect of Thy-1 signaling on cytokine production and the development of T helper (Th) cell phenotypes (Th1, Th2, Th17) remains unclear. The purpose of this work was to further our understanding of Thy-1-mediated signal transduction and the role that Thy-1 plays in the development of effector T cell responses. I found that, in the context of costimulatory signals, anti-Thy-1 mAb induced significantly less IL-2 production, CD25 expression and T cell proliferation than anti-TcR? mAb. Several key signaling molecules, including protein tyrosine kinases, zeta chain-associated protein-70 and extracellular signal-regulated kinase were activated with delayed kinetics during Thy-1-mediated T cell activation. The delayed signaling kinetics resulted in the delayed acquisition of cytotoxic effector function and also delayed delivery of the lethal hit to target cells. Interestingly, Thy-1-mediated signaling induced significantly more IL-17 and IL-4 synthesis and less IFN-? synthesis in comparison to TcR-mediated signaling. Moreover, Thy-1-activated CD4+ T cells produced high levels of IL-17 and IL-4 but minimal IFN? when restimulated with anti-Thy-1 mAb or anti-TcR? mAb with or without costimulatory signals. The unique ability of Thy-1 signaling to induce IL-17 production correlated with the expression of the Th17 lineage-specific transcription factor, retinoic orphan receptor gamma t. These observations show that Thy-1 signaling differs from TcR signaling in its ability to induce Th cell cytokines. Taken together, my findings show that Thy-1 signaling can provide the full TcR-like signal required for both the differentiation and triggering of Th cells and cytotoxic T lymphocytes, albeit with delayed kinetics in comparison to TcR signaling. They also suggest that Thy-1 signaling may be important in the development of Th2 and Th17 responses.

(english) Natural Killers - NK cells play an important role in immune surveilance and regulation either by direct cytotoxicity towards infected, transformed or otherwise damaged cells, or by production of cytokines and chemokines. The resulting response of NK cells is given by the sum of stimulating and inhibiting signals, tranduced by a wide array of receptors. Killer Ig-like receptors KIR2DL4 and LILRB1, which recognize self HLA-G molecules in pregnancy, as well as NKR-P1 receptors, which differ in the number of isotypes, are species-dependent and reduced during phylogenesis. NKG2D, reacting to stress-inducible proteins, and adenosine receptors (AR), which supress the inflamatory reaction, remain evolutionary conserved. The aim of this work was to study the involvement of NK cells and their receptors in several immune disorders and in various species, to provide new insights into their function and posisible immune modulation. We have shown here, that the choice of species in the study of NK cell effector functions may be crucial in some cases. The reaction to glycans, using synthetic GlcNAc-terminated glycomimetics GN8P, exerted opposing effects on NK cell function in humans and C57Bl/6 mice. In humans, the glycomimetic decreased cytotoxic activity of high NKR-P1A expressing NK cells, while in...

Os neutrófilos são os leucócitos circulantes mais abundantes. Apesar de serem importantes no combate às infecções, o intenso recrutamento e a consequente ativação dessas células levam à liberação de mediadores inflamatórios que estão relacionados com o agravamento do quadro clínico de inúmeras doenças. Dessa forma, nos últimos anos tem-se intensificado a procura por substâncias terapêuticas que minimizem os danos teciduais ocasionados pela infiltração neutrofílica. Estudos prévios do grupo de pesquisa mostraram que as 3-fenilcumarinas, que constituem uma classe de produtos naturais de origem vegetal, são substâncias promissoras como moduladores do metabolismo oxidativo de neutrófilos. Em continuidade a essas investigações, o derivado sintético 3-fenilcumarínico 6,7-diidroxi-3-[3\',4\'- metilenodioxifenil]-cumarina (C13) foi selecionado, por apresentar o grupo substituinte ortodiidroxi nas posições C-6 e C-7 do esqueleto cumarínico e a metilenodioxila ligada ao anel fenílico, no intuito de avaliar o seu efeito nas demais funções efetoras dos neutrófilos, como também em um modelo animal de inflamação articular. Foi avaliado o efeito modulatório in vitro da C13 sobre a quimiotaxia, a produção de ERO e interação com o sítio ativo da mieloperoxidase (MPO), a fagocitose de imunocomplexos (IC), a desgranulação da enzima elastase, a atividade microbicida sobre Candida albicans, a mobilização e o influxo de cálcio, a polimerização do citoesqueleto, e a formação e liberação das NETs em neutrófilos humanos. A C13 inibiu, de forma dependente da concentração, o metabolismo oxidativo de neutrófilos estimulados via receptores de IgG (Fc?R) e/ou de complemento (CR), utilizando-se diferentes tipos de IC e foi capaz de interagir com o sítio ativo da MPO. Nas concentrações próximas da necessária para inibir 50% do metabolismo oxidativo (~ 2µmol/L), a C13 não interferiu nas demais funções efetoras dos neutrófilos avaliadas. No entanto, na maior concentração avaliada (20 µmol/L), a C13 inibiu cerca de: 30% da capacidade das células de migrar a favor dos agentes quimiotáticos n-formil-metionil-leucil-fenilalanina (fMLP) e leucotrieno B4; 70% da fagocitose de IC mediada por CR; 40% e 80% da desgranulação estimulada por fMLP e IC imobilizados, respectivamente; 50% do processo de formação e liberação das NETs. Esta concentração de C13 também interferiu na polimerização do citoesqueleto de actina, mas não inibiu: a quimiotaxia de neutrófilos frente à interleucina (IL) 8; a capacidade fagocítica de IC estimulada via Fc?R e Fc?R+CR; e a atividade microbicida sobre C. albicans. Na segunda parte deste trabalho, foi avaliada a toxicidade da C13 sobre neutrófilos mantidos em condições de cultura celular por 6 e 12 h. Nos períodos avaliados, essa substância não alterou a viabilidade dos neutrófilos. Por último, a C13 foi incorporada em vesículas lipossomais e sua atividade biológica foi avaliada em ratos Wistar com inflamação articular induzida por zimosan. O tratamento dos animais com a C13 lipossomal (1mg/Kg) reduziu a formação do edema e a infiltração de leucócitos e neutrófilos na sinóvia inflamada, mas não alterou a concentração sinovial das citocinas inflamatórias fator de necrose tumoral ?, IL-1? e IL-6. Portanto, o derivado 3-fenilcumarínico C13 pode servir de protótipo para o desenvolvimento de novos agentes terapêuticos com aplicação no tratamento de doenças onde há intensa participação dos neutrófilos. / Neutrophils are the most abundant circulating leukocytes. Although neutrophils are important to fight against infections, the massive recruitment and consequent activation of these cells result in the release of inflammatory mediators that are associated with worsening of the clinical condition in many diseases. In this sense, the search for new therapeutic compounds that minimize tissue damage caused by neutrophil infiltration has been intensified in the past few years. Previous studies have demonstrated that 3-phenylcoumarins, a class of plantderived natural compounds, are promising modulators of neutrophil oxidative metabolism. To continue these investigations, we selected the 3-phenylcoumarin derivative 6,7-dihydroxy-3- [3?,4?-methylenedioxyphenyl]-coumarin (C13), bearing the 6,7-dihydroxyl and the 3?,4?- methylenedioxyl groups, to further assess its effects on the other effector functions of neutrophils, as well as on in an animal model of articular inflammation. We examined the in vitro modulator effect of C13 on the human neutrophil chemotaxis, production of ROS and interaction with active site of myeloperoxidase (MPO), phagocytosis of immune complexes (IC), degranulation, killing of Candida albicans, calcium mobilization and influx, cytoskeleton polymerization, and the formation and release of NETs. C13 inhibited, in a concentration-dependent manner, the neutrophil ROS generation elicited via IgG (Fc?R) and/ or complement (CR) receptors using different types of IC and it interacted with active site of MPO. At concentrations near to that required to suppress the ROS production by 50% (~ 2µmol/L), C13 did not modulate the other neutrophil effector functions assessed. However, at the highest concentration tested (20 µmol/L), C13 inhibited nearly: 30% of the cell ability to migrate towards n-formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4; 70% of CR-mediated phagocytosis of IC; 40% and 80% of cell degranulation triggered by fMLP and immobilized IC, respectively; and 50% of the NETs formation and release process. Such C13 concentration also interfered in the actin cytoskeleton polymerization, but it did not suppress the neutrophil: chemotaxis towards interleukin (IL) 8; capacity to phagocytose IC elicited via Fc?R and Fc?R+CR; and killing of C. albicans. In the second part of this study, we examined whether C13 was toxic towards neutrophils maintained in culture for 6 and 12 h. At the time points assessed, this compound did not change the viability of neutrophils. Finally, we incorporated C13 into liposomes and examined its biological activity in Wistar rats of zymosan-induced articular inflammation. Treatment of animals with liposomal C13 reduced edema formation, and leukocyte and neutrophil infiltration in the inflamed synovia, but it did not change the synovial concentration of the inflammatory cytokines tumor necrosis factor ?, IL-1?, and IL-6. Therefore, the 3-phenylcoumarin derivative C13 can be a prototype for the development of novel therapeutic agents to be used in the treatment of diseases where neutrophils have intense participation.

Os neutrófilos são os leucócitos circulantes mais abundantes. Apesar de serem importantes no combate às infecções, o intenso recrutamento e a consequente ativação dessas células levam à liberação de mediadores inflamatórios que estão relacionados com o agravamento do quadro clínico de inúmeras doenças. Dessa forma, nos últimos anos tem-se intensificado a procura por substâncias terapêuticas que minimizem os danos teciduais ocasionados pela infiltração neutrofílica. Estudos prévios do grupo de pesquisa mostraram que as 3-fenilcumarinas, que constituem uma classe de produtos naturais de origem vegetal, são substâncias promissoras como moduladores do metabolismo oxidativo de neutrófilos. Em continuidade a essas investigações, o derivado sintético 3-fenilcumarínico 6,7-diidroxi-3-[3\',4\'- metilenodioxifenil]-cumarina (C13) foi selecionado, por apresentar o grupo substituinte ortodiidroxi nas posições C-6 e C-7 do esqueleto cumarínico e a metilenodioxila ligada ao anel fenílico, no intuito de avaliar o seu efeito nas demais funções efetoras dos neutrófilos, como também em um modelo animal de inflamação articular. Foi avaliado o efeito modulatório in vitro da C13 sobre a quimiotaxia, a produção de ERO e interação com o sítio ativo da mieloperoxidase (MPO), a fagocitose de imunocomplexos (IC), a desgranulação da enzima elastase, a atividade microbicida sobre Candida albicans, a mobilização e o influxo de cálcio, a polimerização do citoesqueleto, e a formação e liberação das NETs em neutrófilos humanos. A C13 inibiu, de forma dependente da concentração, o metabolismo oxidativo de neutrófilos estimulados via receptores de IgG (Fc?R) e/ou de complemento (CR), utilizando-se diferentes tipos de IC e foi capaz de interagir com o sítio ativo da MPO. Nas concentrações próximas da necessária para inibir 50% do metabolismo oxidativo (~ 2µmol/L), a C13 não interferiu nas demais funções efetoras dos neutrófilos avaliadas. No entanto, na maior concentração avaliada (20 µmol/L), a C13 inibiu cerca de: 30% da capacidade das células de migrar a favor dos agentes quimiotáticos n-formil-metionil-leucil-fenilalanina (fMLP) e leucotrieno B4; 70% da fagocitose de IC mediada por CR; 40% e 80% da desgranulação estimulada por fMLP e IC imobilizados, respectivamente; 50% do processo de formação e liberação das NETs. Esta concentração de C13 também interferiu na polimerização do citoesqueleto de actina, mas não inibiu: a quimiotaxia de neutrófilos frente à interleucina (IL) 8; a capacidade fagocítica de IC estimulada via Fc?R e Fc?R+CR; e a atividade microbicida sobre C. albicans. Na segunda parte deste trabalho, foi avaliada a toxicidade da C13 sobre neutrófilos mantidos em condições de cultura celular por 6 e 12 h. Nos períodos avaliados, essa substância não alterou a viabilidade dos neutrófilos. Por último, a C13 foi incorporada em vesículas lipossomais e sua atividade biológica foi avaliada em ratos Wistar com inflamação articular induzida por zimosan. O tratamento dos animais com a C13 lipossomal (1mg/Kg) reduziu a formação do edema e a infiltração de leucócitos e neutrófilos na sinóvia inflamada, mas não alterou a concentração sinovial das citocinas inflamatórias fator de necrose tumoral ?, IL-1? e IL-6. Portanto, o derivado 3-fenilcumarínico C13 pode servir de protótipo para o desenvolvimento de novos agentes terapêuticos com aplicação no tratamento de doenças onde há intensa participação dos neutrófilos. / Neutrophils are the most abundant circulating leukocytes. Although neutrophils are important to fight against infections, the massive recruitment and consequent activation of these cells result in the release of inflammatory mediators that are associated with worsening of the clinical condition in many diseases. In this sense, the search for new therapeutic compounds that minimize tissue damage caused by neutrophil infiltration has been intensified in the past few years. Previous studies have demonstrated that 3-phenylcoumarins, a class of plantderived natural compounds, are promising modulators of neutrophil oxidative metabolism. To continue these investigations, we selected the 3-phenylcoumarin derivative 6,7-dihydroxy-3- [3?,4?-methylenedioxyphenyl]-coumarin (C13), bearing the 6,7-dihydroxyl and the 3?,4?- methylenedioxyl groups, to further assess its effects on the other effector functions of neutrophils, as well as on in an animal model of articular inflammation. We examined the in vitro modulator effect of C13 on the human neutrophil chemotaxis, production of ROS and interaction with active site of myeloperoxidase (MPO), phagocytosis of immune complexes (IC), degranulation, killing of Candida albicans, calcium mobilization and influx, cytoskeleton polymerization, and the formation and release of NETs. C13 inhibited, in a concentration-dependent manner, the neutrophil ROS generation elicited via IgG (Fc?R) and/ or complement (CR) receptors using different types of IC and it interacted with active site of MPO. At concentrations near to that required to suppress the ROS production by 50% (~ 2µmol/L), C13 did not modulate the other neutrophil effector functions assessed. However, at the highest concentration tested (20 µmol/L), C13 inhibited nearly: 30% of the cell ability to migrate towards n-formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4; 70% of CR-mediated phagocytosis of IC; 40% and 80% of cell degranulation triggered by fMLP and immobilized IC, respectively; and 50% of the NETs formation and release process. Such C13 concentration also interfered in the actin cytoskeleton polymerization, but it did not suppress the neutrophil: chemotaxis towards interleukin (IL) 8; capacity to phagocytose IC elicited via Fc?R and Fc?R+CR; and killing of C. albicans. In the second part of this study, we examined whether C13 was toxic towards neutrophils maintained in culture for 6 and 12 h. At the time points assessed, this compound did not change the viability of neutrophils. Finally, we incorporated C13 into liposomes and examined its biological activity in Wistar rats of zymosan-induced articular inflammation. Treatment of animals with liposomal C13 reduced edema formation, and leukocyte and neutrophil infiltration in the inflamed synovia, but it did not change the synovial concentration of the inflammatory cytokines tumor necrosis factor ?, IL-1?, and IL-6. Therefore, the 3-phenylcoumarin derivative C13 can be a prototype for the development of novel therapeutic agents to be used in the treatment of diseases where neutrophils have intense participation.

No description available.