Determinação dos genótipos para o polimorfismo dos receptores de IgG, FcγRlla (H/R131) e FcγRIIIb (NA1/NA2), e estudo do burst oxidativo dos neutrófilos em indivíduos infectados pelo HIV e/ou Mycobacterium tuberculosis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identificação de peptídeos de Escherichia coli capazes de inibir a própria fagocitose em sepse

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

Burst oxidativo dos neutrófilos humanos: estudo da influência do polimorfismo do receptor para IgG FeyRIIIb na cooperação com os receptores para complemento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

HtrA, RseP, and Tsp do not elicit a pathology related serum IgG response during sexually transmitted infection with Chlamydia trachomatis

Chlamydia trachomatis sexually transmitted infection can cause serious reproductive morbidities. This study determined the prevalence of serum IgG response to C. trachomatis putative stress response proteins in females to test for an association with genital tract pathology. There was no significant association of serum IgG to HtrA, Tsp, or RseP with infection or pathology. cHSP60 serum IgG prevalence was significantly associated with infection compared to negative (infertile) controls (p = 0.002), but not with upper genital tract pathology. Serum IgG1-4 antibody subclasses reactive with the antigens was not significantly different between cohorts, although different responses to each antigen were detected.

Transport of IgG across the blood-luminal barrier of the male reproductive tract of the rat and the effect of estradiol administration on reabsorption of fluid and IgG by the epididymal ducts

In rats immunized systemically with tetanus toxoid the concentration of specific anti-tetanus-toxoid-specific IgG in fluid from the rete testis and cauda epididymidis were respectively 0.6% and 1.4% the concentration in blood serum. The extratesticular duct system reabsorbed 97% of the IgG and 99% of the fluid leaving the rete, but estradiol administration affected the site of reabsorption. In untreated rats, the ductuli efferentes reabsorbed 94% of the IgG and 96% of the fluid leaving the rete, whereas estradiol-treated rats reabsorbed 83% of the IgG and 86% of the fluid, and the ductus epididymidis fully compensated for these different effects of estradiol on the ductuli efferentes. The concentrations of IgG in secretions of the seminal vesicles and prostate gland were lower (0.1% and 0.3% respectively of the titers in blood serum) than in fluids from the extratesticular ducts, and were not affected by the administration of estradiol. RT-PCR showed that Fcgrt (neonatal Fc receptor, also known as FcRn) is expressed in the reproductive ducts, where IgG is probably transported across epithelium, being particularly strong in the ductuli efferentes (where most IgG was reabsorbed) and distal caput epididymidis. It is concluded that IgG enters the rete testis and is concentrated only 2.5-fold along the extratesticular duct system, unlike spermatozoa, which are concentrated 95-fold. Further, the ductus epididymidis can recognize and compensate for changes in function of the ductuli efferentes.

Divergent outcomes following transcytosis of IgG targeting intracellular and extracellular chlamydial antigens

Antibodies can play a protective but non-essential role in natural chlamydial infections dependent on antigen specificity and antibody isotype. IgG is the dominant antibody in both male and female reproductive tract mucosal secretions, and is bi-directionally trafficked across epithelia by the neonatal Fc receptor (FcRn). Using physiologically relevant pH-polarized epididymal epithelia grown on Transwells®, IgG specifically targeting an extracellular chlamydial antigen; the Major Outer Membrane Protein (MOMP), enhanced uptake and translocation of infection at pH 6-6.5 but not at neutral pH. This was dependent on FcRn expression. Conversely, FcRn-mediated transport of IgG targeting the intracellular chlamydial inclusion membrane protein A (IncA), induced aberrant inclusion morphology, recruited autophagic proteins independent of lysosomes, and significantly reduced infection. Challenge of female mice with MOMP-specific IgG-opsonized C. muridarum delayed infection clearance but exacerbated oviduct occlusion. In male mice, MOMP-IgG elicited by immunization afforded no protection against testicular chlamydial infection, whereas; the transcytosis of IncA-IgG significantly reduced testicular chlamydial burden. Together these data show that the protective and pathological effects of IgG are dependent on FcRn-mediated transport as well as the specificity of IgG for intracellular or extracellular antigens.

Allergen capture by IgE and IgG enhanced cell-binding by allergen multimers: How complex is it?

Allergic diseases are the most common chronic disease of the western world, costing $7.8 billion per year in lost productivity and medical care in Australia alone.1 IgE is central to the immunopathogenesis of allergic diseases and important advances are now being made on multiple fronts of IgE research. In particular, two groups independently invested in the generation of IgE reporter mice to address the vexing question of the route of development of the elusive IgE+ B cell.2, 3 Two new anti-IgE mAb targeting membrane IgE and cell-bound IgE have the potential to deplete the cellular source of IgE.4, 5 These could be candidates for alternative anti-IgE treatment options with advantages over current anti-IgE therapy (OmalizumAb), which depletes free serum IgE. Researchers are still intrigued by the modes of interaction of IgE with allergen, and with both its receptors; the high affinity FcεR1 on mast cells and basophils, and the low affinity, C-type lectin, IgE receptor, CD23,6 on B cells and monocytes (Figure 1a and b). A new approach to the study of the complexity of these interactions was recently reported by Reginald et al.7 on page 167 of this issue.

DC-SIGN and alpha 2,6-sialylated IgG Fc interaction is dispensable for the anti-inflammatory activity of IVIg on human dendritic cells

Intravenous immunoglobulin (IVIg) is widely used to treat autoimmune diseases. Several mutually nonexclusive mechanisms are proposed to explain the beneficial effects of IVIg in patients (1, 2). Lately, Ravetch and colleagues (3) demonstrate that anti-inflammatory activity of IVIg is mediated mainly by antibodies that contain terminal _2,6-sialic acid linkages at the Asn297-linked glycan of Fc region.

Factor VIII-hydrolyzing IgG in acquired and congenital hemophilia

Anti-factor VIII (FVIII) inhibitory IgG may arise as alloantibodies to therapeutic FVIII in patients with congenital hemophilia A, or as autoantibodies to endogenous FVIII in individuals with acquired hemophilia. We have described FVIII-hydrolyzing IgG both in hemophilia A patients with anti-FVIII IgG and in acquired hemophilia patients. Here, we compared the properties of proteolytic auto- and allo-antibodies. Rates of FVIII hydrolysis differed significantly between the two groups of antibodies. Proline-phenylalanine-arginine-methylcoumarinamide was a surrogate substrate for FVIII-hydrolyzing autoantibodies. Our data suggest that populations of proteolytic anti-FVIII IgG in acquired hemophilia patients are different from that of inhibitor-positive hemophilia A patients.

Induction of allergen-specific IgE and IgG responses by anti-idiotypic antibodies

In order to explore idiotypic, anti-idiotypic, and anti-anti-idiotypic responses to allergens, BALB/c mice were immunized with affinity- purified human idiotypic antibodies directed against a highly purified shrimp allergen. This resulted in the production of anti-idiotypic antibodies which were quantitated by using rabbit idiotypic antibodies raised against the same purified allergen. The mouse anti-idiotypic antibodies recognized shrimp-specific human idiotypic antibodies of the IgE isotype from 18 of 20 individuals, and IgG antibodies from 14 of 20 shrimp-sensitive patients. Immunization of BALB/c mice with affinity- purified, allergen-specific anti-idiotypic antibodies induced anti- allergen IgE and IgG responses in the absence of the allergen. This paper thus presents evidence that anti-idiotypic antibodies raised against allergen-specific idiotypic antibodies may substitute for the original allergen in the induction of allergen-specific idiotypic antibodies. The demonstration of shared idiotopes on IgG and IgE antibodies in the sera of shrimp-sensitive patients supports the use of allergen-specific anti-idiotypic antibodies as surrogate allergens.

Detection of IgG, IgA, IgM and IgE Antibodies in Invasive Amoebiasis in Endemic Areas

Entamoeba histolytica-specific serum IgG, IgA, IgM and IgE antibodies were assayed in cases of amoebiasis in an endemic area. Patient groups consisted of amoebic liver abscess (n=18), pre-abscess hepatic amoebiasis (n=22) and amoebic colitis (n=30). Control subjects comprised 26 asymptomatic cyst passers, 13 giardiasis cases, 20 typhoid patients and 24 non-amoebic individuals. Serum IgG was assayed by ELISA, using a monoclonal anti IgG β- galactosidase (IgG β-gal) conjugate, a polyclonal avidin biotin horse radish peroxidase (AB-HRP), and a polyclonal anti IgG horse radish peroxidase (IgG HRP) conjugate. IgA and IgM were assayed by the β-gal ELISA and IgE by AB-HRP. Diagnostically significant IgG and IgA while lower IgM and IgE antibody levels were seen in extraintestinal cases. About 40% of suspected pre-abscess hepatic amoebiasis cases were confirmed by antibody estimation. All isotype levels in most dysentery cases were in the range of the controls.

Estudio de la mejora de la precisión en los receptores GPS

El presente proyecto analiza la tecnología utilizada por los sistemas GNSS, su funcionamiento y composición. Estudia varios sistemas GPS comerciales sus características y protocolos utilizados y diferentes programas, para el análisis, gestión y visualización de los datos asociados. El proyecto se centra en estudiar posibles métodos que mejoran la precisión de posicionamiento obtenida por los receptores GPS y propone, después de las correspondientes pruebas, dos métodos basados en DGPS con los que se han obtenido precisiones de unos pocos centímetros.

Análisis de pruebas de campo con canales de multitrayecto severo para determinar los límites de funcionamiento de los receptores DRM

[ES]Mediante el presente documento se realiza el análisis del límite de funcionamiento de los receptores DRM (Digital Radio Mondiale) en el canal de propagación NVIS en particular, que se caracteriza por ser afectado por el multitrayecto severo. Para ello se estudian los valores teóricos y las máscaras de funcionamiento hallados en un proyecto previo llamado “Análisis de los límites de funcionamiento de los receptores DRM en canales con multitrayecto severo”, que se compararán con los valores prácticos que se analizan en este proyecto. A partir de dicha comparativa se obtendrán unos estadísticos que indicarán los puntos de fallo frecuentes así como las razones de los mismos. Además a partir de dichos datos se realizarán unas nuevas máscaras que indican los límites de funcionamiento prácticos debido a las importantes diferencias que se dan entre los datos teóricos y los hallados en este proyecto.

PLASTICIDAD DE LOS RECEPTORES DE LA SEROTONINA EN LAS ASTAS POSTERIORES DE LA MÉDULA ESPINAL DE LA RATA: INTERACCIÓN CON LA NEUROTRANSMISIÓN OPIOIDÉRGICA Y GLUTAMATÉRGICA EN UN MODELO DE DOLOR PERSIST

Una de las principales características de las vías descendentes provenientes de la RVMMes su capacidad para modular la transmisión nociceptiva en la médula espinal de manerabidireccional, es decir su capacidad tanto de facilitarla como de inhibirla. En este trabajomostramos que la activación de los receptores de la serotonina presentes en neuronas dela médula espinal puede tanto aumentar como disminuir los potenciales evocados porfibras C, o bien no producir cambio alguno en los mismos, dependiendo del subtipo dereceptor que se reclute. Demostramos también que la modulación de la nocicepción pormedio de los subtipos 5-HT1A, -2A, -2B, y -4 se modifica profundamente por efecto dela LNR.Datos previos que documentan mecanismos de interacción entre receptores del glutamatoy de la serotonina en otras regiones del SNC nos han conducido a plantear la hipótesis desu posible existencia en neuronas de las astas posteriores y su función en el dolorpersistente. Hemos hallado que la activación del receptor 5-HT2A induce cambiosplásticos de mGluR1 en las astas posteriores a través de un mecanismo intracelulardependiente de PKC. Esta modulación adquiere un papel clave en los signos desensibilización inducidos por la LNR a partir del quinto día posterior a la lesión. Por suparte, la activación del receptor 5-HT2B induce la fosforilación del receptor NMDA en ladensidad sináptica de las neuronas de las astas posteriores tras la LNR. Este mecanismoes mediado por la translocación de la isoforma ¿ de la PKC al espacio sináptico. El papelde 5-HT2B en la sensibilización central predomina en los primeros 2 días post-ligadura, ypierde relevancia en los días sucesivos.Además, la neurotransmisión serotoninérgica mediada por los receptores 5-HT2A y5-HT2B en animales sometidos a ligadura de L5 tiene un impacto negativo sobre laactividad antinociceptiva de los receptores opioides ¿ y ¿ en la médula espinal. Estosresultados sugieren que la intervención sobre los receptores 2A y 2B podría servir de basepara mejorar la eficacia de la analgesia por opioides en personas con dolor crónico.