In this work the involved mechanisms between Ro/SSA complex, composed also by the tripartite motif 21 (TRIM21alpha) and trove domain 2 (TROVE2) proteins, with respect to systemic lupus erythematosus (SLE) autoantibodies is studied. The work is divided in three chapters: I- In vitro and in silico analysis of the molecular recognition between lupus autoantibodies and TRIM21alpha Fc Receptor ; II- In vitro evidence of bipolar-bridged immune TROVE2 complexes in the pathogenesis of systemic lupus erythematosus and III- Label-free piezoelectric biosensor for prognosis and diagnosis of Systemic Lupus Erythematosus. Samples of lupic patients and health subjects were kindly provided by La Fe hospital, accordingly the required protocols. After its extraction and purification, the immunoglobulin samples were obtained to study in vitro protein interactions and the involved mechanism by using a quartz crystal microbalance with dissipation factor attributions, and dual polarization interferometry. Techniques such, polarization modulation infrared interferometry, x-ray photoelectron interferometry and contact angle measurement were used in order to characterize surfaces. Pre-steady-state analysis revealed an antibody bipolar bridging involved in both TRIM21alpha and TROVE2 proteins. Identification of the main immunodominant human linear epitope for TRIM21alpha was finely mapped using a series of overlapping synthetic polypeptides with a size of 21 amino acids. The epitopes recognised by autoantibodies for this protein spanned the linear sequence from the aminoacid 151 to 183, and a conformational epitope for SLE patients and healthy subjects, respectively. Autoantibodies from lupic patients targeted protein epitopes, allowing health subjects to be discriminated. Major Histocompatibility Complex Class-II binding peptide prediction results corroborated the sequence as the immunodominant linear epitope, mostly coded as the HLA DRB1*1304 allele for SLE patients, and HLA DRB1*0806 for controls. The subdominant epitope corresponded to the PRY-SPRY domain, recently known as mammalian Fc receptor. Finally, the TRIM21alpha protein structure was modeled by a new homology modeling, never before presented. From the TROVE2 protein, the major linear epitope recognized by autoantibodies correspond to the sequence from the aminoacid 160 to 210 for healthy subjects. However, the major epitope in SLE serum is undiscovered. We suggest that the difference between epitopes could correspond to a majority necrosis-induced specificity in SLE patients, and an apoptotic via in healthy subjects. TROVE2 showed the ability to bind to Fcs, depending on alkaline earth cations in solution. The results suggest that the TROVE2-TRIM21alpha binding is a calcium-dependent protein interaction linked through the MIDAS-like motif in the vWFA-like domain. Finally, a pratical consequence of all study was the development of label-free biosensing method, based in microbalance technology, for in vitro diagnostics of systemic lupus erythematosus patients, allowing the premature sensing of autoantibodies against TRIM21alpha and TROVE2 protein, in advance of the clinical illness symptoms appear. / En este trabajo se ha estudiado el mecanismo involucrado entre el complejo Ro/SSA, compuesto también por las proteínas tripartite motif 21 alpha(TRIM21alpha;) y trove domain 2 (TROVE2) con respecto a autoanticuerpos de pacientes que tienen lupus eritematoso sistémico, en comparación con autoanticuerpos de personas sanas. El estudio comprende tres capítulos: I- Análisis in vitro e in silico del reconocimiento molecular entre autoanticuerpos de lupus y receptor TRIM21alpha; Fc; II- Evidencias in vitro de complejos inmunes TROVE2 bipolares con puentes en la patogénesis del lupus eritematoso sistémico y III- Biosensor piezoeléctrico libre de marcaje para el pronóstico y el diagnóstico del lupus eritematoso sistémico. Las muestras de pacientes lúpicos y personas sanas fueron proporcionadas por el hospital La Fe de acuerdo con los protocolos establecidos. Tras una etapa de extracción y purificación de las inmunoglobulinas fueron estudiadas la interacción de proteínas in vitro utilizando una microbalanza de cristal de cuarzo con atribución de factor de disipación e interferometria de polarización dual. Técnicas de caracterización como espectroscopía infrarroja de reflexión-absorción por modulación de la polarización, espectroscopía fotoelectrónica de rayos-x y análisis de ángulo de contacto fueron utilizadas con la finalidad de caracterizar superficies. El análisis del estado pre estacionario ha revelado un mecanismo de puente bipolar para las dos proteínas, TRIM21alpha; y TROVE2. Tras su identificación, el epítopo linear inmunodominante fue mapeado para TRIM21alpha;, utilizando una serie de polipéptidos sintéticos superpuestos de 21 aminoácidos. Los epitopos reconocidos por autoanticuerpos para esta proteína abarca la secuencia lineal a partir del aminoácido 151 hasta el 183 para epitopos de pacientes lúpicos y sujetos sanos, respectivamente. Autoanticuerpos de pacientes lúpicos reconocieron epítopos de proteínas, permitiendo la discriminación de pacientes sanos. Los resultados de la unión del Complejo Mayor de Histocompatibilidad clase II con el péptido de unión corroboraron la secuencia cómo el epítopo lineal inmunodominante, codificado como el alelo HLA DRB1 * 1304 para pacientes con LES y HLA DRB1 * 0806 para los controles. El epitopo subdominante corresponde al dominio PRY-SPRY, recientemente conocido receptor Fc de mamífero. Finalmente, la estructura de la proteína TRIM21alpha; fue determinada utilizando un nuevo modelo de homología no presentado antes. De la proteína TROVE2, el epitopo lineal immunodominante reconocido por los autoanticuerpos corresponde a la secuencia que pudiera corresponder del aminoácido 160 hasta 210 para sujetos sanos. Sin embargo, el epitopo mayoritario en sueros lúpicos no fue determinado. Se sugiere que la diferencia entre los epitopos se corresponde mayoritariamente a una necrosis-inducida en pacientes lúpicos, y a una vía apoptótica en pacientes sanos. TROVE2 presentó la habilidad de unirse a Fcs dependiendo de los cationes alcalinos presentes en la disolución. Los resultados sugieren que la unión TROVE2-TRIM21alpha; es dependiente de la interacción con calcio vinculada a través del motivo MIDAS en el dominio vWFA. Finalmente, una consecuencia práctica de todo el estudio fue el desarrollo de un biosensor libre de marcaje para diagnóstico in vitro de lupus eritematoso sistémico, permitiendo la detección prematura de autoanticuerpos anti TRIM21alpha; y anti TROVE2, varios años antes de la aparición de los síntomas clínicos de la enfermedad. / En aquest treball s'ha estudiat el mecanisme involucrat en el complex Ro/SSA, compost per les proteïnes tripartite motif 21 (TRIM21alpha;) i trove domain 2 (TROVE2) respecte a autoanticossos de pacients que tenen lupus eritematós sistèmic, en comparació amb autoanticossos de persones sanes. L'estudi es divideix en tres capítols: : I- Anàlisi in vitro i in silico del reconeixement molecular entre autoanticossos de lupus i receptor TRIM21alpha; Fc; II- Evidències in vitro de complexos immunes TROVE2 bipolars amb ponts en la patogènesi del lupus eritematós sistèmic i III-Biosensor piezoelèctric lliure de marcatge per al pronòstic i el diagnòstic del lupus eritematós sistèmic. Les mostres de pacients lúpics y persones sanes van ser amablement proporcionades per l'hospital La Fe d'acord amb els protocols establerts. Després d'una etapa de purificació adequada, el pool de mostres de immunoglobulines va ser estudiat les interaccions in vitro de les proteïnes utilitzant una microbalança de cristall de quars amb atribució de factor de dissipació i interferometria de polarització dual. Tècniques de caracterització, como ara espectroscòpia de infraroja de reflexió-absorció per modulació de la polarització, espectroscòpia fotoelèctrica de rajos X i anàlisi d'angle de contacte van ser emprades amb per tal de caracteritzar les superfícies. L¿anàlisi de l`estat preestacionari ha revelat un mecanisme de pont bipolar que involucra les dos proteïnes, TRIM21alpha; i TROVE2. Una vegada identificat, va ser mapat l'epítop immunodominant lineal per a TRIM21alpha; emprant una sèrie de polipèptids sintètics superposats de 21 aminoàcids. Els epítops reconeguts per autoanticossos per a aquesta proteïna engloben la seqüència lineal a partir de l'aminoàcid 151 fins al 183 per a epítops de pacients lúpics y subjectes sans, respectivament. Autoanticossos de pacients lúpicos van reconèixer epítops de proteïnes, fet que va permetre la discriminació de pacients sans. Els resultats de la unió del Complexe Major de Histocompatibilitat classe II amb el pèptid de unió van corroborar la seqüència com l'epítop lineal immunodominant, codificat com l'al·lel HLA DRB1 * 1304 per a pacients amb LES i HLA DRB1 * 0806 per als controls. L'epítop subdominant correspon al domini PRY-SPRY, recentment conegut receptor Fc de mamífer. Finalment, l'estructura de la proteïna TRIM21alpha; va ser determinada utilitzant un nou model d'homologia no presentat abans. De la proteïna TROVE2, l'epítop lineal immunodominant reconegut pels autoanticossos correspon a la seqüència que pogués correspondre l'aminoàcid 160 fins al 210 per a subjectes sans. No obstant això, l'epítop majoritari en sèrums lúpics no va ser determinat. Es suggereix que la diferència entre els epítops es correspon majoritàriament a una necrosis induïda en pacients lúpics i a una via apoptòtica en pacients sans. TROVE2 va mostrar l'habilitat de unir-se a Fcs en funció dels cations alcalins presents en la dissolució. Els resultats suggereixen que la unió TROVE2-TRIM21alpha; depèn de la interacció amb calci vinculada a través del motiu MIDAS en el domini vWFA. Finalment, la conseqüència pràctica de tot l'estudi va ser el desenvolupament d'un biosensor sense marcatge per al diagnòstic in vitro de lupus eritematós sistèmic, el qual permet la detecció prematura d'autoanticossos cap a les proteïnes TRIM21alpha; i TROVE2 anys abans de l'aparició dels símptomes clínics de la malaltia. / Do Nascimento, NM. (2017). The Ro/SSA Complex in Systemic Lupus Erythematosus Patients [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80534

La prolongation de l’intervalle électrocardiographique QT est un facteur de risque d’arythmie ventriculaire et de mort subite. Cette anomalie, retrouvée chez certains patients atteints de lupus érythémateux disséminé, pourrait contribuer à la mortalité cardiovasculaire élevée dans cette population. L’anti-Ro/SSA, un auto-anticorps retrouvé chez environ 30% des patients atteints de lupus, est associé à la présence de blocs cardiaques chez le nouveau-né et pourrait aussi augmenter le risque de prolongation pathologique de l’intervalle QT chez l’adulte. Le présent mémoire est constitué de cinq chapitres traitant de l’association potentielle entre l’anticorps anti-Ro/SSA et la prolongation de l’intervalle QT. Le premier chapitre constitue une introduction permettant de mettre en contexte les éléments essentiels à la compréhension du projet d’étude. Le deuxième chapitre constitue une revue de l’état des connaissances actuelles sur le lien potentiel entre anti-Ro/SSA et intervalle QT. Le troisième chapitre présente le projet d’étude par l’intermédiaire d’un article publié dans Arthritis Care and Research. Dans cette étude, les patients de la cohorte de lupiques du Centre Universitaire de santé McGill ont subi des électrocardiogrammes dans l’objectif d’estimer l’association entre l’anti-Ro/SSA et les anomalies électrocardiographiques, en tenant compte d’autres facteurs démographiques et cliniques. L’association entre la prolongation de l’intervalle QT et la présence de l’anti-Ro/SSA a été démontrée (rapports de cotes ajustés de 5.1 à 12.6) et les patients porteurs de l’anti-Ro/SSA pourraient donc bénéficier de dépistage électrocardiographique systématique. Les points faibles et forts de cet article sont discutés dans le quatrième chapitre et des perspectives de recherches futures sont finalement abordées. / QT interval prolongation on the electrocardiogram is a risk factor for ventricular arrhythmias and sudden cardiac death. This abnormality is found in patients with systemic lupus erythematosus and could contribute to the high cardiovascular mortality rate in this population. Anti-Ro/SSA is an auto-antibody presents in about 30% of lupus patients and is associated with congenital cardiac block. This auto-antibody could also increase the risk of pathologic prolongation of the QT interval in adults. This master’s thesis is comprised of five chapters discussing the potential association between anti-Ro/SSA antibody and QT interval prolongation. The first chapter is an introduction to the essential elements for the understanding of the study project. The second chapter is a literature review of the potential link between anti-Ro/SSA and QT interval prolongation. The third chapter presents the study project through an article published in Arthritis Care and Research. In this study, patients from the McGill lupus cohort were invited to undergo electrocardiograms in order to estimate the association between anti-Ro/SSA antibody and electrocardiographic abnormalities, while taking into account the other potentially associated demographic and clinical factors. This study shows an association between anti-Ro/SSA and prolonged QT interval (Odds ratios: 5.1 to 12.6) and patients positive for anti-Ro/SSA may thus benefit from electrocardiographic testing. Strengths and weaknesses of this article are discussed in the fourth chapter and future research areas are finally explored.

La prolongation de l’intervalle électrocardiographique QT est un facteur de risque d’arythmie ventriculaire et de mort subite. Cette anomalie, retrouvée chez certains patients atteints de lupus érythémateux disséminé, pourrait contribuer à la mortalité cardiovasculaire élevée dans cette population. L’anti-Ro/SSA, un auto-anticorps retrouvé chez environ 30% des patients atteints de lupus, est associé à la présence de blocs cardiaques chez le nouveau-né et pourrait aussi augmenter le risque de prolongation pathologique de l’intervalle QT chez l’adulte. Le présent mémoire est constitué de cinq chapitres traitant de l’association potentielle entre l’anticorps anti-Ro/SSA et la prolongation de l’intervalle QT. Le premier chapitre constitue une introduction permettant de mettre en contexte les éléments essentiels à la compréhension du projet d’étude. Le deuxième chapitre constitue une revue de l’état des connaissances actuelles sur le lien potentiel entre anti-Ro/SSA et intervalle QT. Le troisième chapitre présente le projet d’étude par l’intermédiaire d’un article publié dans Arthritis Care and Research. Dans cette étude, les patients de la cohorte de lupiques du Centre Universitaire de santé McGill ont subi des électrocardiogrammes dans l’objectif d’estimer l’association entre l’anti-Ro/SSA et les anomalies électrocardiographiques, en tenant compte d’autres facteurs démographiques et cliniques. L’association entre la prolongation de l’intervalle QT et la présence de l’anti-Ro/SSA a été démontrée (rapports de cotes ajustés de 5.1 à 12.6) et les patients porteurs de l’anti-Ro/SSA pourraient donc bénéficier de dépistage électrocardiographique systématique. Les points faibles et forts de cet article sont discutés dans le quatrième chapitre et des perspectives de recherches futures sont finalement abordées. / QT interval prolongation on the electrocardiogram is a risk factor for ventricular arrhythmias and sudden cardiac death. This abnormality is found in patients with systemic lupus erythematosus and could contribute to the high cardiovascular mortality rate in this population. Anti-Ro/SSA is an auto-antibody presents in about 30% of lupus patients and is associated with congenital cardiac block. This auto-antibody could also increase the risk of pathologic prolongation of the QT interval in adults. This master’s thesis is comprised of five chapters discussing the potential association between anti-Ro/SSA antibody and QT interval prolongation. The first chapter is an introduction to the essential elements for the understanding of the study project. The second chapter is a literature review of the potential link between anti-Ro/SSA and QT interval prolongation. The third chapter presents the study project through an article published in Arthritis Care and Research. In this study, patients from the McGill lupus cohort were invited to undergo electrocardiograms in order to estimate the association between anti-Ro/SSA antibody and electrocardiographic abnormalities, while taking into account the other potentially associated demographic and clinical factors. This study shows an association between anti-Ro/SSA and prolonged QT interval (Odds ratios: 5.1 to 12.6) and patients positive for anti-Ro/SSA may thus benefit from electrocardiographic testing. Strengths and weaknesses of this article are discussed in the fourth chapter and future research areas are finally explored.

<p>Patients with systemic lupus erythematosus (SLE) have elevated levels of interferon (IFN)-α in blood and IFN-α-producing cells in tissues. In the present thesis, we investigate the mechanisms behind the upregulated IFN-α-production in SLE and also show that the IFN-α system is activated in primary Sjögren’s syndrome (pSS), with IFN-α-producing cells in the major affected organ, the salivary glands. The IFN-α is a type I IFN, a family of cytokines counteracting especially viral infections, by acting directly on infected cells, and via many immunomodulatory effects. The latter may also contribute to autoimmune processes.</p><p>The type I IFNs are usually produced upon recognition of microbial structures. In SLE, however, DNA-containing immune complexes (ICs) that induce IFN-α production are found. Many autoantibodies in SLE and pSS are directed to nucleic acids or to DNA/RNA-binding proteins. We show that also RNA in complex with autoantibodies from SLE or pSS patients (RNA-IC) induces IFN-α-production. The RNA could be either in the form of RNA-containing material released from apoptotic or necrotic cells or as a pure RNA-containing autoantigen, the U1 small nuclear ribonucleoprotein particle. </p><p>The IFN-α-production induced by RNA-IC occurred in plasmacytoid dendritic cells (PDCs), also termed natural IFN-producing cells (NIPCs), via binding to Fcγ-receptor IIa, endocytosis and triggering of Toll-like receptors (TLRs), probably TLR7 and TLR9. The RNA-IC may also have other effects, and we found that they induce prostaglandin E2 (PGE2) production in monocytes and tumor necrosis factor (TNF)-α in both monocytes and NIPC/PDC. The PGE2 downregulated the IFN-α induction in NIPC/PDC, and the IFN-α induction was increased in monocyte-depleted cell cultures. </p><p>The findings presented in this thesis aids in the understanding of the mechanisms behind the activated IFN-α system in SLE and other autoimmune diseases, and shows that also pSS is one of these diseases.</p>

Patients with systemic lupus erythematosus (SLE) have elevated levels of interferon (IFN)-α in blood and IFN-α-producing cells in tissues. In the present thesis, we investigate the mechanisms behind the upregulated IFN-α-production in SLE and also show that the IFN-α system is activated in primary Sjögren’s syndrome (pSS), with IFN-α-producing cells in the major affected organ, the salivary glands. The IFN-α is a type I IFN, a family of cytokines counteracting especially viral infections, by acting directly on infected cells, and via many immunomodulatory effects. The latter may also contribute to autoimmune processes. The type I IFNs are usually produced upon recognition of microbial structures. In SLE, however, DNA-containing immune complexes (ICs) that induce IFN-α production are found. Many autoantibodies in SLE and pSS are directed to nucleic acids or to DNA/RNA-binding proteins. We show that also RNA in complex with autoantibodies from SLE or pSS patients (RNA-IC) induces IFN-α-production. The RNA could be either in the form of RNA-containing material released from apoptotic or necrotic cells or as a pure RNA-containing autoantigen, the U1 small nuclear ribonucleoprotein particle. The IFN-α-production induced by RNA-IC occurred in plasmacytoid dendritic cells (PDCs), also termed natural IFN-producing cells (NIPCs), via binding to Fcγ-receptor IIa, endocytosis and triggering of Toll-like receptors (TLRs), probably TLR7 and TLR9. The RNA-IC may also have other effects, and we found that they induce prostaglandin E2 (PGE2) production in monocytes and tumor necrosis factor (TNF)-α in both monocytes and NIPC/PDC. The PGE2 downregulated the IFN-α induction in NIPC/PDC, and the IFN-α induction was increased in monocyte-depleted cell cultures. The findings presented in this thesis aids in the understanding of the mechanisms behind the activated IFN-α system in SLE and other autoimmune diseases, and shows that also pSS is one of these diseases.