RESUMEN

Introduction. The international consensus and the American Society of Hematology guidelines from 2019 established thrombopoietin analogues as the second-line therapy for primary immune thrombocytopenia cases. Objectives. To describe romiplostim usefulness in patients with immune thrombocytopenia in a third-level hospital in Cuenca, Ecuador. Materials and methods. We conducted a descriptive and retrospective study in patients with immune thrombocytopenia treated with romiplostim. We evaluated the following variables: age, gender, previous therapies to romiplostim, dose, frequency, complications, change of thrombopoietin analogue, and treatment discontinuation. Results. We included 21 patients with immune thrombocytopenia treated with romiplostim, with a median age of 49 years. All patients received corticosteroids as first-line treatment. Three patients required longer administration intervals (over a week), with weekly doses lower than those recommended (< 1 µg/kg). Due to lack of efficacy, six patients replaced elthrombopag with romiplostim. Of the total, three suffered thrombotic complications: two had portal venous thrombosis, and one had pulmonary thromboembolism; five of the patients discontinued romiplostim scheme without resuming it. Conclusions. Romiplostim constitutes a convenient second-line therapy in immune thrombocytopenia. Despite the small sample size, romiplostim early use can minimize toxicities and infectious risks.

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Introducción: El consenso internacional y la guía del 2019 de la American Society of Hematology, establecieron a los análogos de la trombopoyetina como medicamentos de segunda línea para tratar la trombocitopenia inmunitaria primaria. En Ecuador, se comercializan dos trombomiméticos: romiplostim y eltrombopag OBJETIVOS: Describir el uso de romiplostim en pacientes con trombocitopenia inmunitaria, en un hospital de tercer nivel en Cuenca (Ecuador). Materiales y métodos. Se adelantó un estudio descriptivo y retrospectivo en pacientes con trombocitopenia inmunitaria y tratamiento con romiplostim. Se evaluaron las siguientes variables: edad, sexo, tratamientos previos a romiplostim, dosis, frecuencia, complicaciones, cambio de análogo de trombopoyetina y discontinuación de la terapia. RESULTADOS: Veintiún pacientes con trombocitopenia inmunitaria fueron tratados con romiplostim, con una mediana de 49 años. Todos recibieron corticoides como tratamiento de primera línea. Tres precisaron de intervalos más prolongados que el semanal, con dosis semanales menores de las recomendadas (< 1 µg/kg). Por falta de eficacia, en seis pacientes se reemplazó la terapia con eltrombopag por romiplostim. Tres pacientes padecieron complicaciones trombóticas: dos, trombosis venosa portal, y uno, tromboembolia pulmonar. En cinco, se discontinuó el tratamiento con romiplostim, sin necesidad de reanudarlo. CONCLUSIONES: Romiplostim constituye un tratamiento de segunda línea para la trombocitopenia inmunitaria primaria. A pesar del reducido tamaño de la muestra, se observó que la administración temprana del medicamento puede minimizar toxicidades y riesgos infecciosos.

Asunto(s)

Benzoatos , Púrpura Trombocitopénica Idiopática , Pirazoles , Receptores Fc , Proteínas Recombinantes de Fusión , Trombopoyetina , Humanos , Proteínas Recombinantes de Fusión/uso terapéutico , Proteínas Recombinantes de Fusión/administración & dosificación , Trombopoyetina/uso terapéutico , Trombopoyetina/administración & dosificación , Persona de Mediana Edad , Estudios Retrospectivos , Femenino , Masculino , Receptores Fc/uso terapéutico , Púrpura Trombocitopénica Idiopática/tratamiento farmacológico , Adulto , Anciano , Pirazoles/uso terapéutico , Benzoatos/uso terapéutico , Benzoatos/administración & dosificación , Hidrazinas/uso terapéutico , Adulto Joven , Receptores de Trombopoyetina/agonistas , Corticoesteroides/uso terapéutico

RESUMEN

The development of specific, safe, and potent monoclonal antibodies (Abs) has led to novel therapeutic options for infectious disease. In addition to preventing viral infection through neutralization, Abs can clear infected cells and induce immunomodulatory functions through engagement of their crystallizable fragment (Fc) with complement proteins and Fc receptors on immune cells. Little is known about the role of Fc effector functions of neutralizing Abs in the context of encephalitic alphavirus infection. To determine the role of Fc effector function in therapeutic efficacy against Venezuelan equine encephalitis virus (VEEV), we compared the potently neutralizing anti-VEEV human IgG F5 (hF5) Ab with intact Fc function (hF5-WT) or containing the loss of function Fc mutations L234A and L235A (hF5-LALA) in the context of VEEV infection. We observed significantly reduced binding to complement and Fc receptors, as well as differential in vitro kinetics of Fc-mediated cytotoxicity for hF5-LALA compared to hF5-WT. The in vivo efficacy of hF5-LALA was comparable to hF5-WT at -24 and + 24 h post infection, with both Abs providing high levels of protection. However, when hF5-WT and hF5-LALA were administered + 48 h post infection, there was a significant decrease in the therapeutic efficacy of hF5-LALA. Together these results demonstrate that optimal therapeutic Ab treatment of VEEV, and possibly other encephalitic alphaviruses, requires neutralization paired with engagement of immune effectors via the Fc region.

Asunto(s)

Anticuerpos Antivirales , Virus de la Encefalitis Equina Venezolana , Animales , Caballos , Humanos , Virus de la Encefalitis Equina Venezolana/genética , Anticuerpos Neutralizantes/farmacología , Receptores Fc , Inmunoglobulina G

RESUMEN

BACKGROUND: RTXM83 is a rituximab biosimilar with proven clinical safety and efficacy. It is the first rituximab biosimilar developed and approved in South America and is currently marketed in several Latin American, Middle Eastern and African countries. OBJECTIVE: The aim of this study was to present the physicochemical and biological characterization studies utilized to demonstrate the similarity between RTXM83 and its reference product. METHODS: Primary and higher order protein structures were analysed using peptide mapping with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), fluorescence spectroscopy and circular dichroism, and micro-differential scanning calorimetry, among other techniques. Charge variants were determined by cation-exchange chromatography (CEX) and capillary isoelectric focusing (cIEF). Glycosylation and glycoforms distribution were analysed using MS, normal phase high-performance liquid chromatography (NP-HPLC) and high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD). Size variants were evaluated by size-exclusion chromatography (SEC), sedimentation velocity analytical ultracentrifugation (SV-AUC), dynamic light scattering (DLS), and capillary electrophoresis-sodium dodecyl sulfate (CE-SDS). Biological characterization included binding assays for complement C1q, CD20, and several Fc receptors (FcRs), as well as potency determination for in vitro apoptosis induction, complement-dependent cytotoxicity (CDC), and antibody-dependent cell-mediated cytotoxicity (ADCC). RESULTS: RTXM83 and the reference product showed identical primary sequences and disulfide bridge patterns, and similarity at higher order protein structures, post-translational modification profiles (amino acid modifications, charge variants, and glycosylation) and levels of purity and process-related impurities. Functional studies demonstrated that RTXM83 is similar to the reference product regarding the three known mechanisms of action of rituximab: CDC, ADCC, and apoptosis induction. Binding affinities to CD20, complement component C1q, and different FcRs were also equivalent. CONCLUSION: RTXM83 is similar to its reference product in all critical quality attributes.

Asunto(s)

Biosimilares Farmacéuticos/química , Biosimilares Farmacéuticos/uso terapéutico , Rituximab/química , Rituximab/uso terapéutico , Citotoxicidad Celular Dependiente de Anticuerpos/fisiología , Antígenos CD20/metabolismo , Cromatografía Líquida de Alta Presión/métodos , Dicroismo Circular/métodos , Complemento C1q/metabolismo , Dispersión Dinámica de Luz/métodos , Electroforesis Capilar/métodos , Glicosilación , Humanos , Mapeo Peptídico/métodos , Receptores Fc/metabolismo , Espectrometría de Masas en Tándem/métodos , Ultracentrifugación/métodos

RESUMEN

Selection from a phage display library derived from human Interleukin-2 (IL-2) yielded mutated variants with greatly enhanced display levels of the functional cytokine on filamentous phages. Introduction of a single amino acid replacement selected that way (K35E) increased the secretion levels of IL-2-containing fusion proteins from human transfected host cells up to 20-fold. Super-secreted (K35E) IL-2/Fc is biologically active in vitro and in vivo, has anti-tumor activity and exhibits a remarkable reduction in its aggregation propensity- the major manufacturability issue limiting IL-2 usefulness up to now. Improvement of secretion was also shown for a panel of IL-2-engineered variants with altered receptor binding properties, including a selective agonist and a super agonist that kept their unique properties. Our findings will improve developability of the growing family of IL-2-derived immunotherapeutic agents and could have a broader impact on the engineering of structurally related four-alpha-helix bundle cytokines.

Asunto(s)

Sustitución de Aminoácidos , Antineoplásicos/farmacología , Interleucina-2/genética , Receptores Fc/efectos de los fármacos , Proteínas Recombinantes de Fusión/farmacología , Animales , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Técnicas de Visualización de Superficie Celular , Supervivencia Celular/efectos de los fármacos , Evolución Molecular , Humanos , Interleucina-2/metabolismo , Ratones , Ratones Endogámicos C57BL , Ingeniería de Proteínas , Receptores Fc/genética

RESUMEN

RESUMEN: Los receptores Fcγ947; (FcγR), específicos para la inmunoglobulina G, les confieren a las células donde se expresan funciones en la respuesta inmunoinflamatoria. La heterogeneidad interindividual en la eficiencia de la función de los FcγR se ha explicado por polimorfismos en los genes que codifican 3 de estos receptores, FcγRIIa, FcγRIIIa y FcγRIIIb, los cuales han sido asociados con susceptibilidad y/o severidad en enfermedades infecciosas y autoinmunes en diferentes poblaciones. En este trabajo se analizan las características clínicas de 94 pacientes chilenos con evidencia de daño periodontal y se establece la frecuencia alélica/genotípica del polimorfismo H131R en el gen FCGR2A que codifica para el receptor FcγRIIa, así como su posible asociación con periodontitis. El polimorfismo G>A (H131R) en el gen FCGR2A se estudió por PCR en tiempo real utilizando sondas TaqMan. En el grupo estudiado se encontró un alto porcentaje de pacientes con periodontitis (86, 2%) y una asociación significativa a edad y sexo. No se observó una asociación a los alelos H o R, ni a los genotipos encontrados (H/R y R/R). Este es el primer trabajo en que se estudia el polimorfismo H131R en el FcγRIIa en población chilena en una muestra de pacientes adecuadamente caracterizados; sin embargo, creemos que es necesario estudiar un mayor número de sujetos para determinar si los polimorfismos de los genes FcγR constituyen o no posibles factores de susceptibilidad a enfermedad periodontal en población chilena.

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ABSTRACT: The Fcγ receptors (FcγR) specific for the immunoglobulin G, expresses for the immune inflammatory response function. The inter individual heterogeneity in the efficiency of the FcγR function has been explained by polymorphisms in genes that encode for 3 of these receptors, FcγRIIa, FcγRIIIa and FcγRIIIb, which have been associated with susceptibility or severity in autoimmune and infectious diseases in different populations. This paper discusses the clinical characteristics of 94 Chilean patients with evidence of periodontal damage and establishes the allelic/genotypic frequency of polymorphism H131R in the FCGR2A gene, which encodes for the receptor FcγRIIa, as well as their possible association with periodontitis. Polymorphism G>A (H131R) in the gene FCGR2A was studied via real time PCR using TaqMan probes. In the study group, a high percentage of patients with periodontitis was found (86, 2%) with a significant association with age and gender. No determination could be reached as to whether the allele H or R or the genotypes found (H/R and R/R) were a factor of genetic susceptibility. This is the first study to determine the polymorphisms of the FcγR gene in a Chilean population adequately characterized; nevertheless, we believe that it is necessary to study a greater number of subjects in order to determine if the polymorphisms of the FcγR gene are a possible factors of susceptibility to periodontal disease in the Chilean population.

Asunto(s)

Humanos , Masculino , Femenino , Enfermedades Periodontales , Periodontitis , Polimorfismo Genético , Receptores Fc , Frecuencia de los Genes , Chile , Estudios Transversales

RESUMEN

PROBLEM: IgG is the only antibody class, that is, actively transferred from the mother to the fetus across the placenta by an active, neonatal Fc receptor (FcRn) mediated process during pregnancy, conferring passive immunity and protection against infections to the newborn during the first months of life. Preterm infants may not receive sufficient titers of protective antibodies, as most of them are transferred only after the 34th week of gestation. Because of the great importance of this process, we investigated in a clinical setting the placental transmission of IgG antibodies in term and preterm newborns. METHOD OF STUDY: This work was conducted in 85 woman and their newborns, divided into four groups according to their clinical gestational age (≤37 weeks were considered as preterm). Blood samples were collected from the mothers and their newborns' umbilical cords to analyze total serum IgG concentrations, and a subgroup of 32 placentas was analyzed by immunohistochemistry to quantify the expression of the FcRn receptor. RESULTS: Total IgG levels in both mothers and neonates increased significantly through the third trimester of gestation. Regarding the newborns, in all groups, IgG levels exceeded their mother's values by a ~2.4%. A higher expression of FcRn was detected in placentas from newborns at week 36 of gestation onwards. CONCLUSION: Our results obtained from clinical samples, were in line with previous descriptions in model systems and confirmed that the IgG transfer from maternal serum to the fetus is positively correlated with FcRn expression in placental tissue throughout gestation.

Asunto(s)

Antígenos de Histocompatibilidad Clase I/metabolismo , Inmunoglobulina G/sangre , Intercambio Materno-Fetal , Placenta/metabolismo , Nacimiento Prematuro/inmunología , Receptores Fc/metabolismo , Adulto , Femenino , Humanos , Inmunohistoquímica , Recién Nacido , Recien Nacido Prematuro , Embarazo

RESUMEN

This study investigated the expression of the neonatal Fc receptor (FcRn) in maternal blood, cord blood and placental cells and determined IgG levels in maternal blood and cord blood from diabetic mothers. Peripheral blood, cord blood and placenta samples were collected from 26 mothers with normoglycaemia (non-diabetic, ND group) and 52 with hyperglycaemia (26 with mild gestational hyperglycaemia, MGH group, and 26 with type 2 diabetes mellitus, DM-2 group). Cells expressing CD19(+) and FcRn were identified by flow cytometry. Total IgG and its subclasses were quantified by ELISA. Maternal blood from DM-2 and cord blood from MGH exhibited a higher proportion of CD19(+) expression by B cells. DM-2 showed a lower proportion of CD19(+) cells in placenta. FcRn expression increased in cells from cord blood and placenta from MGH. Maternal blood, cord blood and placenta cells from DM-2 showed lower FcRn expression. Blood IgG levels were lower in DM-2, and cord blood IgG levels were higher in MGH. The highest levels of IgG4 were detected in the blood of hyperglycaemic mothers. The highest IgG3 and IgG4 levels in cord blood were detected in MGH, and the lowest IgG2 and IgG3 levels in DM-2. Maternal hyperglycaemia compromised placental transfer of IgG1, IgG3 and IgG4. The results suggest that regardless of hyperglycaemia degree, it decreases FcRn expression in placenta and blood cells and compromises the production and transfer of antibodies from maternal blood to newborns.

Asunto(s)

Diabetes Mellitus Tipo 2/inmunología , Diabetes Gestacional/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Intercambio Materno-Fetal/inmunología , Placenta/inmunología , Receptores Fc/inmunología , Adulto , Antígenos CD19/genética , Antígenos CD19/inmunología , Estudios Transversales , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patología , Diabetes Gestacional/sangre , Diabetes Gestacional/genética , Diabetes Gestacional/patología , Femenino , Sangre Fetal/inmunología , Feto , Expresión Génica , Antígenos de Histocompatibilidad Clase I/genética , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina G/genética , Recién Nacido , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/patología , Placenta/patología , Embarazo , Receptores Fc/genética

RESUMEN

Immunoglobulin G (IgG) Fc N-glycosylation affects antibody-mediated effector functions and varies with inflammation rooted in both communicable and non-communicable diseases. Worldwide, communicable and non-communicable diseases tend to segregate geographically. Therefore, we studied whether IgG Fc N-glycosylation varies in populations with different environmental exposures in different parts of the world. IgG Fc N-glycosylation was analysed in serum/plasma of 700 school-age children from different communities of Gabon, Ghana, Ecuador, the Netherlands and Germany. IgG1 galactosylation levels were generally higher in more affluent countries and in more urban communities. High IgG1 galactosylation levels correlated with low total IgE levels, low C-reactive protein levels and low prevalence of parasitic infections. Linear mixed modelling showed that only positivity for parasitic infections was a significant predictor of reduced IgG1 galactosylation levels. That IgG1 galactosylation is a predictor of immune activation is supported by the observation that asthmatic children seemed to have reduced IgG1 galactosylation levels as well. This indicates that IgG1 galactosylation levels could be used as a biomarker for immune activation of populations, providing a valuable tool for studies examining the epidemiological transition from communicable to non-communicable diseases.

Asunto(s)

Enfermedades Transmisibles/inmunología , Inmunoglobulina G/química , Polisacáridos/química , Receptores Fc/química , Schistosoma/inmunología , Esquistosomiasis/inmunología , Adolescente , Animales , Biomarcadores/química , Proteína C-Reactiva/metabolismo , Niño , Preescolar , Ecuador , Femenino , Gabón , Alemania , Ghana , Glicosilación , Humanos , Inmunoglobulina E/sangre , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Inflamación/inmunología , Masculino , Países Bajos , Esquistosomiasis/parasitología

RESUMEN

Transforming growth factor ß1 (TGFß1) plays a key role in T cell homeostasis and peripheral tolerance. We evaluated the influence of a novel human mutant TGFß1/Fc (human IgG4 Fc) fusion protein on memory CD4+ and CD8+ T cell (Tmem) responses in vitro and their recovery following antithymocyte globulin (ATG)-mediated lymphodepletion in monkeys. TGFß1/Fc induced Smad2/3 protein phosphorylation in rhesus and human peripheral blood mononuclear cells and augmented the suppressive effect of rapamycin on rhesus Tmem proliferation after either alloactivation or anti-CD3/CD28 stimulation. In combination with IL-2, the incidence of CD4+ CD25hi Foxp3hi regulatory T cells (Treg) and Treg:Th17 ratios were increased. In lymphodepleted monkeys, whole blood trough levels of infused TGFß1/Fc were maintained between 2 and 7 µg/mL for 35 days. Following ATG administration, total T cell numbers were reduced markedly. In those given TGFß1/Fc infusion, CD8+ T cell recovery to predepletion levels was delayed compared to controls. Additionally, numbers of CD4+ CD25hi CD127lo Treg increased at 4-6 weeks after depletion but subsequently declined to predepletion levels by 12 weeks. In all monkeys, CD4+ CD25hi Foxp3hi Treg/CD4+ IL-17+ cell ratios were reduced, particularly after stopping TGFß1/Fc infusion. Thus, human TGFß1/Fc infusion may delay Tmem recovery following lymphodepletion in nonhuman primates. Combined (low-dose) IL-2 infusion may be required to improve the Treg:Th17 ratio following lymphodepletion.

Asunto(s)

Homeostasis/inmunología , Memoria Inmunológica/inmunología , Depleción Linfocítica/efectos adversos , Receptores Fc/metabolismo , Linfocitos T Reguladores/inmunología , Factor de Crecimiento Transformador beta1/metabolismo , Animales , Humanos , Leucocitos Mononucleares/inmunología , Macaca mulatta , Masculino , Receptores Fc/genética , Factor de Crecimiento Transformador beta1/genética

RESUMEN

Insulin resistance is a key feature of obesity and type 2 diabetes mellitus (T2DM). Interaction of insulin with the insulin receptor (IR) leads to both its auto-phosphorylation and phosphorylation of tyrosine residues on the IR substrate (IRS) proteins, initiating the activation of intracellular signaling cascades. The metabolic effects of IRS are known to be mediated through pathways involving phosphatidyl-inositol 3-kinase (PI-3K), which result in the activation of Akt signaling. The C-terminal region of the IR ectodomain is required to facilitate the conformational changes that are required for high-affinity binding to insulin. Furthermore, the CH2 and CH3 domains in the Fc fragments of immunoglobulins are responsible for their binding to the Fc receptor, which triggers transcytosis. In this study, we created a fusion peptide of the C-terminal end of the human IR ectodomain with the IgG4 Fc fragment, including an intervening polyG fragment to ensure enough space for insulin binding. We named this new peptide "Yiminsu", meaning an insulin sensitizer. The results of our analyses show that Yiminsu significantly facilitates insulin signaling via the activation of Akt in hepatocytes in a dose- and time-dependent manner. Further studies are required to determine whether Yiminsu can act as an insulin sensitizer.

Asunto(s)

Diabetes Mellitus Tipo 2/tratamiento farmacológico , Fragmentos Fab de Inmunoglobulinas/farmacología , Inmunoglobulina G/farmacología , Insulina/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Recombinantes de Fusión/farmacología , Animales , Células CHO , Línea Celular , Clonación Molecular/métodos , Cricetulus , Diabetes Mellitus Tipo 2/metabolismo , Relación Dosis-Respuesta a Droga , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Humanos , Fragmentos Fab de Inmunoglobulinas/química , Fragmentos Fab de Inmunoglobulinas/genética , Inmunoglobulina G/química , Inmunoglobulina G/genética , Resistencia a la Insulina , Fosfatidilinositol 3-Quinasa/metabolismo , Fosforilación/efectos de los fármacos , Ingeniería de Proteínas , Estructura Terciaria de Proteína , Receptor de Insulina/metabolismo , Receptores Fc/metabolismo , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Transducción de Señal/efectos de los fármacos , Tirosina/metabolismo

RESUMEN

The neonatal Fc receptor (FcRn) plays an important role in regulating IgG homeostasis in the body and passive protection to the offspring. Changes in FcRn expression levels caused by genetic polymorphisms of Fcgrt, which encodes FcRn, may lead to inter-individual differences in colostrum IgG levels in sheep. In this study, we sequenced the FcRn partial heavy chain from 179 sheep from Xinjiang Province, China, and detected the differences in colostrum IgG levels and Fcgrt genotypes to identify the correlation between the Fcgrt genotype and colostrum IgG levels in 4 sheep breeds. The DNA sequencing of a 680-bp fragment of the Fcgrt gene revealed various patterns depending on the single-strand conformation in the Suffolk breed. Sequencing analysis revealed a total of 3 patterns, AA, BB, AB, in this fragment, among which the absence of AB and BB genotype acted as a marker for breed identification and characterization, while the AA genotype was shared by Suffolk and 3 other breeds. The only allele found in all 4 breeds was allele A, indicating that natural selection may be favoring the AB and BB genotypes in general and B allele in particular, as the colostrum IgG concentration was relatively higher in the Suffolk breed compared to the other 3 breeds.

Asunto(s)

Calostro/inmunología , Antígenos de Histocompatibilidad Clase I/genética , Inmunoglobulina G/metabolismo , Polimorfismo Genético , Receptores Fc/genética , Oveja Doméstica/genética , Oveja Doméstica/inmunología , Alelos , Animales , Secuencia de Bases , Femenino , Datos de Secuencia Molecular , Embarazo , Análisis de Secuencia de ADN

RESUMEN

Introdução: Sepse é uma síndrome complexa definida por resposta inflamatória sistêmica, de origem infecciosa e caracterizada por manifestações múltiplas que podem determinar disfunção ou falência de um ou mais órgãos ou sistemas. É a principal causa de morte em unidades de terapia intensiva em pacientes críticos e tem representado uma fonte constante de preocupação para os sistemas de saúde em todo o mundo, devido, principalmente, às taxas elevadas de morbimortalidade. O tratamento da sepse é um desafio e continua a ser uma tarefa difícil devido a inúmeros fatores interferentes. Um estudo do nosso grupo demonstrou que a Escherichia coli (E. coli) é capaz de se ligar CD16 de um modo independente de opsonina, levando a um aumento na resposta inflamatória e a inibição da sua própria fagocitose, por conseguinte, procurou-se identificar os peptídeos no proteoma da E. coli envolvidos neste cenário. Metodologia: Utilizando a metodologia de Phage Display, que consiste numa técnica de clonagem, que permite a expressão de diversas sequências de peptídeos na superfície de bacteriófagos, nós identificamos 2 peptídeos que obtiveram interação com CD16. Após a seleção dos peptídeos identificamos uma proteína de membrana de E.coli que possui alta similaridade com um de nossos peptídeos selecionados. Nós acreditamos que esta proteína de membrana possa estar envolvida no processo de evasão imune desenvolvida pela E.coli e parece ser um forte candidato como uma nova opção terapêutica para controlar infecções por E. coli. Conclusão: A identificação de proteínas capazes de induzir inibição de fagocitose, através do receptor CD16, pode ser usada como uma nova forma de tratamento da sepse, assim como explorada no tratamento de doenças autoimunes.

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Introduction: Sepsis is a complex syndrome defined by a systemic inflammatory response of infectious origin and characterized by multiple manifestations that can determine dysfunction/failure of one or more organs and systems. It is the leading cause of death in intensive care units and represents a major health problem around the world, mainly due to its high mortality and morbidity rates. The treatment of sepsis is challenging and remains a difficult task due to numerous interfering factors. A study from our group demonstrated that Escherichia coli (E. coli) is able to bind CD16 in an opsoninindependent manner, leading to an increase in the inflammatory response and inhibition of its own phagocytosis, therefore we sought to identify the peptides in the E. coli proteome involved in this scenario. Methods and Results: Using the Phage Display technique, which is a cloning technique that allows the expression of various peptide sequences on the surface of bacteriophages (phages) and selecting these on the basis of affinity for a target molecule, we identified two peptides that interact with CD16. Next, using bioinformatic tools, we found an E. coli membrane protein that has high similarity with one of our selected peptides. We believe this membrane protein is involved in the process of immune evasion developed by E. coli and it is a strong candidate as a new therapeutic option to control E. coli infections. Conclusion: The identification of proteins capable of inducing inhibition of phagocytosis through the CD16 receptor, can be used as a new treatment of sepsis, as well as exploited in the treatment of autoimmune diseases.

Asunto(s)

Escherichia coli , Inmunoglobulina G , Inflamación , Biblioteca de Péptidos , Fagocitosis , Receptores Fc , Receptores de IgG , Sepsis , Síndrome de Respuesta Inflamatoria Sistémica

Asunto(s)

Benzoatos/uso terapéutico , Hidrazinas/uso terapéutico , Púrpura Trombocitopénica Idiopática/tratamiento farmacológico , Pirazoles/uso terapéutico , Receptores Fc/uso terapéutico , Proteínas Recombinantes de Fusión/uso terapéutico , Trombopoyetina/uso terapéutico , Femenino , Humanos , Masculino

RESUMEN

OBJECTIVES: To determine the safety, tolerability, or efficacy of 2 licensed thrombopoietic agents in children with persistent and chronic immune thrombocytopenia (ITP). STUDY DESIGN: Retrospective analysis approved by the institutional review board of children with ITP not on-study who received thrombopoietin (TPO) therapy; 21 received romiplostim (11 at Children's Hospital of Orange County, 10 at Weill Cornell Medical Center) and 12 received eltrombopag (all at Weill Cornell Medical Center). Primary response measures were platelet counts ≥ 50 × 10(9)/L or ≥ 20 × 10(9)/L above baseline for 2 consecutive weeks and 50% of platelet counts ≥ 50 × 10(9)/L. Duration of treatment and adverse events, including bone marrow myelofibrosis (MF) consensus grades, were tabulated. RESULTS: Twenty-seven of 33 (82%) patients responded to TPO agents, 18 of 21 to romiplostim, and 9 of 12 to eltrombopag, after an average of 3.6 previous ITP therapies. These 27 patients had platelet counts ≥ 50 × 10(9)/L and ≥ 20 × 10(9)/L above baseline for 2 consecutive weeks; 26 had 50% of platelet counts ≥ 50 × 10(9)/L. Duration of romiplostim use ranged from 6 to 44 months (11/18 ongoing) and of eltrombopag 23 to 53 months (7/12 ongoing). One patient on eltrombopag experienced a provoked deep-vein thrombosis at site of ankle fracture. No other serious drug-related adverse events occurred. Among 24 bone marrows, 10 after greater than 2 years of therapy, 23 were normal (MF grades 0-1); 1 was MF-2. CONCLUSION: Retrospective analysis of off-study use of TPO agents in children with mainly chronic ITP showed increases in platelet counts in more than 4 of 5 children. The long-term use of TPO agents, up to 53 months, without tachyphylaxis supports their efficacy. These agents appear safe, effective, and tolerable in children with chronic ITP.

Asunto(s)

Benzoatos/uso terapéutico , Hidrazinas/uso terapéutico , Púrpura Trombocitopénica Idiopática/tratamiento farmacológico , Pirazoles/uso terapéutico , Receptores Fc/uso terapéutico , Proteínas Recombinantes de Fusión/uso terapéutico , Trombopoyetina/uso terapéutico , Adolescente , Niño , Preescolar , Enfermedad Crónica , Femenino , Humanos , Masculino , Estudios Retrospectivos , Adulto Joven

RESUMEN

Today, dengue viruses are the most prevalent arthropod-borne viruses in the world. Since the 1960s, numerous reports have identified a second heterologous dengue virus (DENV) infection as a principal risk factor for severe dengue disease (dengue hemorrhagic fever/dengue shock syndrome, DHF/DSS). Modifiers of dengue disease response include the specific sequence of two DENV infections, the interval between infections, and contributions from the human host, such as age, ethnicity, chronic illnesses and genetic background. Antibody-dependent enhancement (ADE) of dengue virus infection has been proposed as the early mechanism underlying DHF/DSS. Dengue cross-reactive antibodies raised following a first dengue infection combine with a second infecting virus to form infectious immune complexes that enter Fc-receptor-bearing cells. This results in an increased number of infected cells and increased viral output per cell. At the late illness stage, high levels of cytokines, possibly the result of T cell elimination of infected cells, result in vascular permeability, leading to shock and death. This review is focused on the etiological role of secondary infections (SI) and mechanisms of ADE.

Asunto(s)

Acrecentamiento Dependiente de Anticuerpo , Virus del Dengue/inmunología , Virus del Dengue/patogenicidad , Dengue Grave/patología , Dengue Grave/virología , Complejo Antígeno-Anticuerpo/metabolismo , Permeabilidad Capilar , Humanos , Receptores Fc/metabolismo , Factores de Riesgo , Dengue Grave/inmunología , Choque , Internalización del Virus

RESUMEN

A 58-year-old woman presented with rheumatoid arthritis-associated Evans syndrome (simultaneous autoimmune hemolytic anemia and autoimmune thrombocytopenic purpura); she was treated unsuccessfully with steroids, romiplostin, rituximab, immunoglobulin G, and splenectomy. The platelet count responded to the combined use of prednisone, eltrombopag, and romiplostin. It may be more reasonable to use combined treatments than sequential monotherapies.

Asunto(s)

Anemia Hemolítica Autoinmune/terapia , Benzoatos/uso terapéutico , Hidrazinas/uso terapéutico , Prednisona/uso terapéutico , Pirazoles/uso terapéutico , Receptores Fc/uso terapéutico , Proteínas Recombinantes de Fusión/uso terapéutico , Trombocitopenia/terapia , Trombopoyetina/uso terapéutico , Enfermedad Aguda , Anemia Hemolítica Autoinmune/patología , Anticuerpos Monoclonales de Origen Murino/uso terapéutico , Combinación de Medicamentos , Femenino , Humanos , Hidrocortisona/uso terapéutico , Inmunoglobulinas Intravenosas/uso terapéutico , Persona de Mediana Edad , Rituximab , Esplenectomía , Trombocitopenia/patología , Resultado del Tratamiento

RESUMEN

Immunoglobulin G (IgG) has covalently linked a sugar chain in the crystallizable fragment (Fc). This structure consists of double stranded glycosidic complexes with a high degree of heterogeneity that contribute to define the affinity to their specific receptors, and partly determine their biological activity. Recently was identified an anti-inflammatory mechanism mediated by IgG based on their different alternatives of Fc glycosylation and their interaction with the specific adhesion receptor of dendritic cells (DC-SIGN). This mechanism has clinical and therapeutic implications in autoimmune diseases. The objective of this review is to describe the biochemical structure of sugars associated to the Fc of IgG and its variants in relation to specific functions and pathogenicity, particularly in tuberculosis, in which may also have therapeutic implication.

Asunto(s)

Anticuerpos/química , Glicoproteínas/química , Procesamiento Proteico-Postraduccional , Anticuerpos/inmunología , Anticuerpos/metabolismo , Afinidad de Anticuerpos , Citotoxicidad Celular Dependiente de Anticuerpos , Reacciones Antígeno-Anticuerpo , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/metabolismo , Secuencia de Carbohidratos , Moléculas de Adhesión Celular/metabolismo , Glicoproteínas/inmunología , Glicoproteínas/metabolismo , Glicosilación , Humanos , Fragmentos Fc de Inmunoglobulinas/química , Fragmentos Fc de Inmunoglobulinas/metabolismo , Inmunoglobulina G/química , Inmunoglobulina G/inmunología , Inmunoglobulina G/metabolismo , Infecciones/inmunología , Lectinas Tipo C/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Polisacáridos/química , Conformación Proteica , Mapeo de Interacción de Proteínas , Receptores de Superficie Celular/metabolismo , Receptores Fc/química , Receptores Fc/metabolismo , Relación Estructura-Actividad

RESUMEN

Clinical benefits of probiotics have been clearly reported in different gastrointestinal disorders, many of them caused by enterobacteria. The oral cavity is a port of entry and can be an important reservoir of these microorganisms. This work evaluated whether consumption of probiotics was able to influence the presence of enterobacteria in the oral cavity and the specific secretory response against these microorganisms. Saliva samples of healthy individuals were collected and plated in MacConkey agar. Carriers of Gram-negative, rod-shaped microorganisms in the oral cavity were selected and instructed to use the probiotic Yakult LB for 20 days. Saliva was then collected and enterobacteria species were identified using the API 20 E system and by ELISA using anti-enterobacteria IgA. The results showed reduction in the prevalence of enterobacteria, but no significant changes in enterobacterial counts (log CFU/mL; p = 0.3457). The species most frequently isolated were Enterobacter cloacae and Klebsiella oxytoca, both before and after probiotic consumption. No significant changes were observed in anti-enterobacteria IgA levels. In conclusion, probiotic consumption had some influence on enterobacterial presence in the oral cavity, but did not affect enterobacterial counts or the specific immune secretory response against them.

Asunto(s)

Enterobacteriaceae/aislamiento & purificación , Boca/microbiología , Probióticos/administración & dosificación , Análisis de Varianza , Recuento de Colonia Microbiana , Ensayo de Inmunoadsorción Enzimática , Humanos , Boca/inmunología , Receptores Fc/análisis , Saliva/microbiología , Factores de Tiempo

RESUMEN

Clinical benefits of probiotics have been clearly reported in different gastrointestinal disorders, many of them caused by enterobacteria. The oral cavity is a port of entry and can be an important reservoir of these microorganisms. This work evaluated whether consumption of probiotics was able to influence the presence of enterobacteria in the oral cavity and the specific secretory response against these microorganisms. Saliva samples of healthy individuals were collected and plated in MacConkey agar. Carriers of Gram-negative, rod-shaped microorganisms in the oral cavity were selected and instructed to use the probiotic Yakult LB for 20 days. Saliva was then collected and enterobacteria species were identified using the API 20 E system and by ELISA using anti-enterobacteria IgA. The results showed reduction in the prevalence of enterobacteria, but no significant changes in enterobacterial counts (log CFU/mL; p = 0.3457). The species most frequently isolated were Enterobacter cloacae and Klebsiella oxytoca, both before and after probiotic consumption. No significant changes were observed in anti-enterobacteria IgA levels. In conclusion, probiotic consumption had some influence on enterobacterial presence in the oral cavity, but did not affect enterobacterial counts or the specific immune secretory response against them.

Asunto(s)

Humanos , Enterobacteriaceae/aislamiento & purificación , Boca/microbiología , Probióticos/administración & dosificación , Análisis de Varianza , Recuento de Colonia Microbiana , Ensayo de Inmunoadsorción Enzimática , Boca/inmunología , Receptores Fc/análisis , Saliva/microbiología , Factores de Tiempo

RESUMEN

The effects of secretory immunoglobulin A (SIgA) interaction with its specific Fcα receptors on colostral phagocytes needs further investigation, especially with respect to diabetic women. Accordingly, we studied the colostrum of hyperglycemic women to assess SIgA interactions with Fcα receptors of macrophages as well as the functional activity of these cells. The women were divided for colostrum sampling according to their glycemic status: normoglycemia (N = 51), mild hyperglycemia (N = 23), and diabetes (N = 25) groups. We determined the FcαR expression, the IgA on the surface and the surface-bound IgA in colostrum macrophages. We also evaluated the superoxide release and bactericidal killing of these cells. Colostral phagocytes expressed FcαR, contained IgA on the surface and are able to bind to purified SIgA. The bactericidal activity of colostral phagocytes from the hyperglycemic women was similar to that of normoglycemic only when SIgA was used as opsonin. Addition of a MoAb anti-human Fcα receptor resulted in a significant decrease of superoxide release and bacterial killing by macrophages when bacteria were opsonized with purified SIgA, suggesting an interaction between SIgA and FcαR. The stimulatory effects of SIgA on the functional activity of phagocytes therefore protect infants, especially of diabetic women, against intestinal infections.

Asunto(s)

Calostro/inmunología , Diabetes Mellitus/inmunología , Inmunoglobulina A Secretora/inmunología , Fagocitosis/inmunología , Embarazo en Diabéticas/inmunología , Receptores Fc/inmunología , Adolescente , Calostro/citología , Calostro/microbiología , Estudios Transversales , Diabetes Mellitus/microbiología , Escherichia coli/inmunología , Infecciones por Escherichia coli/inmunología , Infecciones por Escherichia coli/microbiología , Infecciones por Escherichia coli/prevención & control , Femenino , Citometría de Flujo , Humanos , Inmunoglobulina A Secretora/farmacología , Recién Nacido , Macrófagos/citología , Macrófagos/inmunología , Persona de Mediana Edad , Embarazo , Adulto Joven