Introdução: O envolvimento hepático na doença celíaca (DC) é amplamente reconhecido e atualmente é uma das manifestações extra-intestinais mais freqüentes. Com o advento de marcadores sorológicos de elevada especificidade e sensibilidade, sobretudo o anticorpo antiendomísio (EMA), a DC tem sido descrita em associação a várias hepatopatias. Objetivos: caracterizar as formas de triagem de DC em portadores de hepatopatia crônica; caracterizar e estudar os pacientes cujo diagnóstico de DC foi realizado durante a investigação de uma doença hepática; pesquisar a reatividade do antiendomísio em pacientes com hepatite auto-imune, cirrose biliar primária, colangite esclerosante primária e hipertensão portal não cirrótica; avaliar o comportamento da doença hepática na vigência de dieta sem glúten. Métodos: Os pacientes foram triados pela detecção dos anticorpos anti-reticulina e anticorpo antimatriz extracelular durante a rotina de imunofluorescência de pesquisa dos auto-anticorpos hepáticos; pela presença de manifestações de DC em hepatopatas crônicos, pelo aspecto endoscópico sugestivo de DC e pela pesquisa sistemática do EMA nas patologias referidas anteriormente. Todos os pacientes foram submetidos à pesquisa do EMA, anti-reticulina IgG ou antimatriz de fibroblastos IgG na presença de deficiência de IgA. Em caso de positividade desses marcadores, foram submetidos à endoscopia digestiva alta para biópsia intestinal e caracterizados do ponto de vista clínico, laboratorial e histopatológico. A evolução desses dados permitiu a caracterização da evolução da doença hepática e da doença celíaca a partir da introdução da dieta sem glúten. Resultados: Foram identificados 43 pacientes com auto-anticorpos relacionados à DC (em 42 o EMA IgA e em um o antimatriz extracelular IgG em associação com deficiência de IgA). A rotina de pesquisa de auto-anticorpos hepáticos identificou 31 pacientes; seis apresentavam hepatopatia crônica e manifestação de DC; em três o exame endoscópico foi sugestivo de DC e a pesquisa sistemática do EMA foi positiva em três casos. O diagnóstico de DC foi confirmado em 37 de 40 pacientes (92,5%) em que a biópsia intestinal foi realizada. A idade dos pacientes variou de 2 a 68 anos, com mediana de 35 anos. Houve maior prevalência de acometimento no sexo feminino (65%). A DC foi mais prevalente na raça branca (87%), mais foi identificada em quatro mulatos e um negro. As doenças hepáticas mais freqüentes foram hipertransaminasemia criptogênica, hepatite auto-imune, hiperplasia nodular regenerativa e hepatite pelo vírus C. Conclusões: 1) A reatividade do anti-reticulina, a presença de diarréia inexplicada e a análise endoscópica da mucosa duodenal foram as formas de seleção mais efetivas de se identificar a DC em hepatopatas crônicos. 2) A ausência de manifestações clínicas de DC nesse grupo de pacientes foi bastante expressiva. 3) A pesquisa sistemática do EMA em cirrose biliar primaria, hepatite auto-imune, colangite esclerosante primária não contribuiu para o diagnóstico de DC em um número significativo de pacientes, ao contrário do observado no grupo de hipertensão portal não cirrótica, especialmente hiperplasia nodular regenerativa 4) As doenças hepáticas em que mais freqüentemente foi diagnosticada a DC foram a hiperplasia nodular regenerativa, hepatite auto-imune, hipertransaminasemia criptogênica, hepatite pelo vírus C e cirrose biliar primária antimitocôndria negativo. 5) A retirada do glúten da dieta contribuiu de maneira efetiva para normalização das enzimas hepáticas nos casos de hipertransaminasemia criptogênica. Nos grupos de hiperplasia nodular regenerativa, hepatite B e C, cirrose biliar primária, álcool e hepatite auto-imune, o papel da dieta foi de difícil avaliação em razão da interferência da instituição do tratamento específico e da evolução natural da doença hepática de base. / Introduction: The hepatic involvement in Celiac Disease (CD) is well known and widely regarded as a frequent extra-intestinal manifestation. With the advent of highly specific and sensitive serological markers, especially the antiendomysial antibody (EMA), CD has been described in association with several liver conditions. Objectives: To characterize ways for screening patients with chronic liver conditions in order to diagnose CD, to characterize and study patients whose CD diagnoses were performed when investigating hepatic diseases, to test the reactivity of EMA in patients with autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis and non-cirrhotic portal hypertension, to evaluate the course of the hepatic disease in gluten-free diet. Methods: Patients were selected by the detection of antireticulin and anti-extracellular matrix antibodies during routine immunoflourescence determination for hepatic autoantibodies, by the presence of CD manifestations in chronic patients with liver diseases, by the endoscopic aspects suggestive of CD and by systematic search for EMA in the above mentioned pathologies. All patients were submitted to tests for EMA, antireticulin IgG or antimatrix of IgG fibroblasts in IgA deficiency. When testing positive for these markers, patients were submitted to upper digestive endoscopy for intestinal biopsy, and were also characterized from the clinical, laboratorial and histological point of view. The assessment of these data enabled the characterization of the hepatic condition as well as the CD from the onset of a gluten-free diet. Results: 43 patients with autoantibodies related to CD were identified (42 tested positive for IgA EMA and 1 for IgG extracellular antimatrix in the presence of IgA deficiency). Routine determination of hepatic autoantibodies identified 31 patients. Of those, 6 presented chronic liver diseases and CD manifestations. In 3 patients, the endoscopic exam was suggestive of CD; systematic EMA determination was positive in all three cases. The CD diagnosis was confirmed in 37 out of 40 patients (92.5%) that performed intestinal biopsy. Patients aged between 2 and 68 years (median: 35 years). Female patients were most affected (65%). CD was more prevalent in white patients (87%), but was also found in four mulattoes and 1 black person. The most common liver disorders were cryptogenic hypertransaminasemia, autoimmune hepatitis, nodular regenerative hyperplasia and chronic hepatitis C. Conclusions: 1) The reactivity of antireticulin, the presence of unexplained diarrhea and the endoscopic analysis of the duodenal mucous were the most effective ways to identify CD in chronic liver diseases. 2) The absence of CD clinical manifestations in this group of patients was impressive. 3) Contrary to what was observed in the group with non-cirrhotic portal hypertension, especially regenerative nodular hyperplasia, the systematic determination of EMA in primary biliary cirrhosis, autoimmune hepatitis and primary sclerosing cholangitis did not contribute to CD diagnosis in a significant number of patients. 4) CD was most frequently diagnosed in the following liver diseases: cryptogenic hypertransaminasemia, autoimmune hepatitis, nodular regenerative hyperplasia and chronic hepatitis C and negative antimitochondrial primary biliary cirrhosis. 5) The removal of gluten from the diet contributed effectively to bring the hepatic enzymes levels back to normal in cases of cryptogenic hypertransaminasemia. However, the role of diet was difficult to evaluate in nodular regenerative hyperplasia, autoimmune hepatitis, alcohol disease and primary biliary cirrhosis groups due to the nature of the specific treatments and the natural course of the hepatic conditions.

Introdução: Os pênfigos vulgar (PV) e foliáceo (PF) são dermatoses autoimunes vésico-bolhosas que apresentam anticorpos da classe IgG dirigidos contra desmogleínas 1 (Dsg) 1 e 3, cuja consequência é a clivagem intraepitelial (acantólise). Objetivo: Caracterizar o perfil clínico e imunológico dos doentes de PF ou PV com envolvimento umbilical. Métodos: Dez pacientes de pênfigo (vulgar ou foliáceo) com manifestação umbilical, acompanhados no Hospital das Clínicas, Departamento de Dermatologia da Faculdade de Medicina da Universidade de São Paulo foram analisados no período entre agosto de 2008 e janeiro de 2010, segundo suas características clínicas, histopatológicas e imunológicas (imunofluorescência direta, indireta e ELISA utilizando Dsg1 e Dsg3 recombinantes). Resultados: Os dados demográficos identificaram que, dos 10 pacientes incluídos, sete eram mulheres, e três homens; a idade variou entre 2470 anos, e a duração da enfermidade entre três e 16 anos. Cinco pacientes foram diagnosticados como PV e cinco como PF. Eritema, erosões, crostas e lesões vegetantes foram as características clínicas mais relevantes presentes nas regiões umbilicais. A imunofluorescência direta (IFD) da região umbilical mostrou depósitos de IgG e C3 intercelulares intraepiteliais em oito doentes, e IgG isolada em dois indivíduos. A imunofluorescência indireta (IFI) com conjugado IgG mostrou padrão típico intercelular de pênfigo em todos os 10 pacientes, com títulos variando entre 1 : 160 e 1:2560. ELISA Dsg1 recombinante mostrou índices de 24 a 266 no PF, e de 0 a 270 no PV. A reatividade contra Dsg3 recombinante foi positiva em todos os pacientes com PV (ELISA 2298), e mostrou-se negativa em todos os soros de PF. Conclusões: Todos os 10 pacientes com pênfigo com manifestação umbilical demonstraram perfil clínico e imunológico compatíveis com PF ou PV. Esta apresentação peculiar, ainda não bem elucidada, é raramente descrita na literatura. Uma possível explicação para esta apresentação distinta pode ser atribuída à presença de novos epítopos, ou uma associação com vestígios embrionários ou de cicatrizaçào, localizados na região do cordão umbilical / Background: Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune vesicobullous disorders with IgG autoantibodies directed against desmoglein (Dsg)1 and 3, which lead to intraepidermal acantholysis. Aim: To characterize the clinical and immunological profile of patients with PF or PV with umbilical involvement. Methods: Ten patients from the Outpatient Clinic, Hospital das Clínicas, Departamento de Dermatologia da Faculdade de Medicina da Universidade de São Paulo, diagnosed with either PV (n = 5) or mucocutaneous PF (n = 5) with umbilical lesions were assessed according to their clinical features, histopathology and immunological findings [direct and indirect immunofluorescence (DIF and IIF) and ELISA with recombinant Dsg1 and Dsg3]. Patients were evaluated from August 2008 to January 2010. Results: Demographic data showed that from 10 patients, seven were women, and three men; age ranged from24 to70 years-old, disease duration was from 3 to 16 years). Erythema, erosions, crusts and vegetating skin lesions were the main clinical features of the umbilical region. DIF of the umbilical lesion gave positive results for intercellular epidermal IgG and C3 deposits in eight patients and for IgG alone in the other two. Indirect immunofluorescence with IgG conjugate showing the typical pemphigus pattern was positive in all 10 patients, with titres varying from 1: 160 to 1:2560. ELISA with recombinant Dsg1 gave scores of 24266 in PF and 0 270 in PV. Reactivity to recombinant Dsg3 was positive in all five patients with PV (ELISA 2298) and was negative in all PF sera. Conclusions: All 10 patients diagnosed as pemphigus with umbilical presentation had the clinical and immunopathological features of either PF or PV. This peculiar presentation, not yet completely elucidated, has been rarely reported in the literature. A possible explanation for this unique presentation may be the presence of either novel epitopes or an association with embryonic or scar tissue located in the umbilical-cord region

Glaucoma is the leading cause of irreversible blindness, estimated to affect more than 79 million people by the year 2020. It is a group of optic neuropathies that is found to be associated with autoimmunity. One of its types is exfoliative glaucoma which is more prevalent in certain areas of the world including Scandinavia. It is more aggressive and often resistant to conventional therapy. The best treatment options for glaucoma lies at the early detection of the disease. The aim of the study was to identify serum biomarkers in patients of exfoliative glaucoma in the Scandinavian population. Serum samples of 30 patients of exfoliative glaucoma and 10 control subjects were profiled on epoxy coated protein microarrays expressing immobilized His-tagged human antigens. 3072 antigens were selected after a literature review which included the ones expressed in eye and retina. Protein-microarrays were incubated with sera, and occurring immunoreactivities were visualized with fluorescence labelled secondary antibodies. To detect changes, spot intensities were digitized and analysed with different statistical methods. Binary logistic regression was used to classify diseased and controls. A significant increase of antibodies against IRAK4 antigen was detected among serum samples of the controls (p = 0.002) as compared to the exfoliative glaucoma patients. Antibodies against four other antigens were found to be more prevalent in serum samples of exfoliative glaucoma patients although not significantly. These included FUT2, VAV2, and GPATCH8 and PFKFB1. The logistic regression was able to classify diseased and controls with 100 percent accuracy depending on 11 selected reactive antigens. Out of the 3072 antigens, IRAK4 was found to be the only significant antigen with increased reactivity in controls as compared to exfoliative glaucoma patients. IRAK4 has a role in innate immunity and signal transduction, antibodies against it may have a neuroprotective effect in glaucoma. However, this is an initial exploratory study based on only 40 samples and further experiments with a larger sample size needs to be performed. / None

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 115-127.

Thyroid dysfunction is one of the most common endocrine disorders in women of childbearing age and the obstetric consequences of abnormal thyroid hormone levels during pregnancy have been established. Less understood is the implication of the presence of maternal thyroid autoantibodies on infant outcomes among women who are euthyroid during pregnancy. The objective of this study was two-fold: 1) to examine the influence of antenatal thyroperioxidase (TPO) status on fetal/infant brain and body growth measurements at delivery and 2) to explore the relationship of antenatal TPO status and maternal postpartum thyroid dysfunction (PPTD) on early infant growth and neurocognitive development. Six-hundred thirty-one (631) euthyroid pregnant women were recruited from prenatal clinics in Tampa Bay, Florida and the surrounding area between November 2007 and December 2010. TPO status was determined during pregnancy and fetal/infant brain and body growth variables were assessed at delivery. A subsample of forty-one (41) mother-infant dyads participated in a 6-month longitudinal supplemental study. Infant growth assessments were conducted at 3, 4, 5 and 6 months postpartum. Regression analysis revealed maternal TPO positivity was significantly associated with smaller head circumference, reduced brain weight and lower brain-body-ratio; however maternal race/ethnicity was identified as an effect modifier in the relationship. No significant differences were noted in birth weight, birth length, abdominal circumference or chest circumference measurements among infants born to TPO positive mothers of any racial/ethnic group as compared to their negative counterparts. Mixed model analysis of the smaller subset (n=41) revealed infants of TPO+ mothers were smaller at birth but experienced accelerated growth between birth to 3 months when compared to infants born to TPO- mothers. This acceleration led to their catch-up in growth to their TPO negative counterparts by 3 months of age. No significant differences were noted in neurocognitive outcomes between infants born to TPO+ mothers compared to those born to TPO- mothers. The findings in this dissertation indicate that maternal/race ethnicity modifies the relationship between TPO positivity and reduced fetal/infant brain growth. Additionally, the analyses suggest that maternal autoantibody status could lead to variations in early infant growth and development. The end-result of these variations is unclear. Further research is needed to determine the potential impact of reduced head circumference and accelerated growth as it relates to long-term neurocognitive consequences. Currently, TPO antibody status is not assessed as part of the standard prenatal care laboratory work-up, but findings from this study suggest that fetal brain growth may be impaired by TPO positivity among certain populations, therefore autoantibody screening among high-risk sub-groups may be useful for clinicians to determine whether prenatal thyroid treatment is warranted.

No description available.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by production of a wide range of autoantibodies, multiple organ involvement and by local formation or tissue deposition of immune complexes (ICs) in the inflamed organs. In contrast to most systemic inflammatory conditions, and despite raised levels of pro-inflammatory cytokines, SLE flares are rarely reflected by elevated C-reactive protein (CRP), an important acute-phase reactant in man with homologs in vertebrates and several invertebrates. As a part of the innate immune system, CRP binds certain molecules exposed on the surface of dying cells/apoptotic bodies and on the surface of pathogens and mediates their elimination by uptake in the reticuloendothelial system. CRP also interacts with IgG-containing immune complexes, binds Fc receptors and activates the complement system via C1q. The aims of this thesis were to investigate the complement activation properties of CRP; to elucidate if anti-CRP antibodies occur in SLE and, if so, whether anti-CRP antibody levels correlate with disease activity in SLE; to test the hypothesis that autoantibodies to pro-inflammatory cytokines prevent rise of CRP; and to survey if autoantibodies to certain nuclear antigens or to CRP correlate with cytokine-inducing properties of ICs from SLE sera. We have demonstrated that CRP bound to phosphorylcholine is a powerful activator of the classical complement pathway already in the CRP concentration range 4 to 10 mg/L, but with a marked inhibition at CRP levels above 150 mg/L. Autoantibodies to the monomeric form of CRP were found in approximately 40 percent of SLE patients and in a few sera from patients with primary Sjögren’s syndrome, but not in rheumatoid arthritis or in inflammatory bowel disease. The anti-CRP antibody levels showed significant correlations to several laboratory and clinical measurements, and anti-CRP positivity was associated with renal involvement in SLE. Native CRP levels were not correlated with anti-CRP or anti-cytokine antibody levels. Hence, the presence of antibodies to monomeric CRP or to CRP-inducing cytokines is an unlikely explanation to the relative failure of CRP response in patients with active lupus. However, antibodies to TNFα were found in subnormal levels at disease flares, whereas antibodies to TGFβ were found in supranormal levels as compared to healthy subjects. In contrast to antibodies against CRP and DNA, anti-SSA and anti-SSB antibodies may regulate the inflammatory process in SLE by enhancing IC formation and subsequent production of cytokines such as IL-6, IL-10 and IL-12p40. Hypothetically, anti-CRP autoantibodies may be of pathogenic importance, for instance by binding to monomeric CRP on cell and tissue surfaces and thereby increasing the risk of extrahepatic deposition of apoptotic material and in situ formation of ICs. / On the day of the defence data the status of article I was Submitted and the tile was "C-reactive protein activates or inhibits the classical complement pathway in a concentration dependent manner" and the status of article V was: Submitted.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Μελετήθηκαν επιδηµιολογικές, κλινικές, βιοχηµικές, ιολογικές και ανοσολογικές παράµετροι σε ασθενείς αιµοκαθαιρόµενους για χρόνια νεφρική ανεπάρκεια µε HCV λοίµωξη και συγκρίθηκαν µε τις αντίστοιχες παραµέτρους HCV µολυνθέντων ασθενών µε φυσιολογική νεφρική λειτουργία. 1) Η µελέτη µας έδειξε ότι οι αιµοκαθαιρόµενοι ασθενείς µε HCV λοίµωξη είχαν σηµαντικά µικρότερες τιµές αµινοτρανσφερασών από αυτούς που είχαν φυσιολογική νεφρική λειτουργία. Από αυτό συµπεραίνεται ότι στους αιµοκαθαιρόµενους, για να εκτιµηθούν οι αµινοτρανσφεράσες σαν βιοχηµικοί δείκτες της ηπατίτιδας C θα πρέπει να διορθώνονται όσον αφορά την υποαµινοτρανσφερασαιµία των αιµοδιυλιζοµένων. 2) Οι αιµοδιυλιζόµενοι είχαν χαµηλότερο ιικό φορτίο από τους ασθενείς µε φυσιολογική νεφρική λειτουργία, σε αντίθεση µε άλλους ανοσοκατεσταλµένους ασθενείς που παρουσιάζουν υψηλότερο ιικό φορτίο από τους ανοσοϊκανούς µε HCV λοίµωξη. Με το χαµηλότερο ιικό φορτίο πιθανώς συσχετίζεται ο µικρότερος βαθµός νεκροφλεγµονώδους δραστηριότητας που ανευρέθη στην βιοψία του ήπατος αυτών των ασθενών. 3) Η συχνότητα κρυοσφαιριναιµίας των αιµοκαθαιροµένων ασθενών δεν διέφερε από αυτών µε φυσιολογική νεφρική λειτουργία, αλλά οι αιµοκαθαιρόµενοι παρουσίαζαν µικρότερες τιµές κρυοκρίτη και κανείς εξ αυτών δεν εµφάνισε κλινικό σύνδροµο κρυοσφαιριναιµίας. Επίσης η συχνότητα ανευρέσεως θετικού ρευµατοειδούς παράγοντος ήταν µικρότερη ενώ τα επίπεδα του C4 κλάσµατος του συµπληρώµατος ήταν υψηλότερα στους αιµοκαθαιρόµενους ασθενείς. Αυτά τα ευρήµατα υποδηλώνουν σχετική ανεπάρκεια του µηχανισµού δηµιουργίας αυτοαντισωµάτων και ανοσοσυµπλεγµάτων στους αιµοκαθαιρόµενους ασθενείς. 4) Οι αιµοδιυλιζόµενοι ασθενείς µε HCV λοίµωξη παρουσίαζαν ξηρά κερατοεπιπεφυκίτιδα σε παρόµοιο ποσοστό µε τους HCV ασθενείς µε φυσιολογική νεφρική λειτουργία, αλλά η ανοσολογική αντίδραση των δακρυικών αδένων έναντι του ιού της ηπατίτιδας C ήταν µάλλον µικρότερη. Η ξηρά κερατοεπιπεφυκίτιδα στους ασθενείς µε HCV λοίµωξη έδειξε να συνδυάζεται µε µεγάλη ηλικία και µεγαλύτερο στάδιο ηπατικής ίνωσης. 5) Τέλος, οι αιµοκαθαιρόµενοι ασθενείς ανευρέθησαν να έχουν µικρότερο βαθµό νεκροφλεγµονώδους δραστηριότητας και ίνωσης από τους ασθενείς µε φυσιολογική νεφρική λειτουργία και πιθανώς µάλιστα ηπιώτερη νόσο όσον αφορά όλες τις παραµέτρους αυτής. / We studied epidemiological, clinical, biochemical, virological and immunological characteristics of HCV infected patients on chronic hemodialysis for end stage renal failure and we compared them to those of otherwise normal patients with chronic HCV infection. 1) Our study showed that the mean values of aminotransferases were significantly lower in hemodialysis patients compared to patients with normal renal function. Our data suggest that in patients undergoing hemodialysis aminotransferases levels should be interpreted, for evaluation of hepatitis C activity, after correction for hypoaminotransferasemia of the hemodialysis population. 2) HCV viral load was found significantly lower in patients on maintenance hemodialysis than in the group with normal renal function. This contrasts with the high HCV viral load that is usually found in other immunocompromised patients. The lower grading of necroinflammatory activity, which was found in liver biopsy samples of hemodialysis patients, is possibly related to the lower viral load in these patients. 3) Prevalence of cryoglobulinemia in HCV-infected hemodialysis patients was not different from that of patients with normal renal function, but hemodialysis patients had lower cryocrit values and none of them presented a cryoglobulinemic syndrome. Rheumatoid factor positivity rate was also lower in hemodialysis group, while complement C4 levels were higher in these patients. These findings denote less efficient mechanism of creating autoantibodies and immune complexes in this population. 4) Patients on hemodialysis infected with HCV have a similar percentage of keratoconjunctivitis sicca with normal renal function HCV patients. Nevertheless hepatitis C virus appears to incite lower immunologic response to lacrimal glands in uremic as opposed to otherwise normal patients. Keratoconjunctivitis sicca in patients with chronic HCV infection was associated with older age and higher staging score of fibrosis in liver biopsy. 5) Finally, hemodialysis patients were found to have lower grading and staging score than those with normal renal function and possibly less severe disease from every aspect.

Οι υποδοχείς της ακετυλοχολίνης (AChRs) είναι διαμεμβρανικές πρωτεΐνες ενεργοποιούμενες με τη δέσμευση της ακετυλοχολίνης (ACh). Με κριτήρια, όπως η χημική συγγένεια που εμφανίζουν για σηματοδότικά μόρια και οι φαρμακολογικές τους ιδιότητες, ταξινομούνται στην ομάδα των νικοτινικών AChRs και στην ομάδα των μουσκαρινικών AChRs. Οι νικοτινικού τύπου υποδοχείς δημιουργούνται από τη συναρμογή πέντε ομόλογων υπομονάδων και υποδιαιρούνται σε μυϊκού τύπου, ευρισκόμενους κυρίως στους σκελετικούς μύες των σπονδυλωτών και σε νευρικού τύπου, απαντώμενους κατά κύριο λόγο στο κεντρικό και περιφερικό νευρικό σύστημα. Οι AChRs σχετίζονται με σειρά παθολογικών καταστάσεων, μεταξύ των οποίων και η βαρειά μυασθένεια (Myasthenia Gravis-MG). Η μυασθένεια χαρακτηρίζεται από χρόνια μυϊκή αδυναμία, προκαλούμενη από τη δράση αντισωμάτων υψηλής συγγένειας έναντι του μυϊκού τύπου AChR. Με απώτερο σκοπό τη διερεύνηση της παθογονικότητας των αυτοαντισωμάτων έναντι μεμονωμένων υπομονάδων του AChR, προχωρήσαμε στην παραγωγή ανασυνδυασμένων πολυπεπτιδικών τμημάτων των υπομονάδων στο ζυμομύκητα Pichia pastoris. Τα πολυπεπτίδια χρησιμοποιήθηκαν στην παρασκευή χρωματογραφικών-ανοσοπροσροφητικών στηλών, που εφαρμόστηκαν ακολούθως για την απομόνωση αυτοαντισωμάτων από επιλεγμένους ορούς μυασθενικών ατόμων. Η παθογόνος δράση των απομονωμένων αυτοαντισωμάτων ελέχθηκε μέσω της προκαλούμενης απώλειας υποδοχέων (αντιγονική τροποποίηση-antigenic modulation) σε κυτταρική σειρά (ΤΕ671) που εκφράζει τον AChR και μέσω της χορήγησή τους σε πειραματόζωα και τον έλεγχο της εμφάνισης χαρακτηριστικών συμπτωμάτων της νόσου. Εκτενής συγκριτική μελέτη μεταξύ τεσσάρων επιλεγμένων ορών και αντισωμάτων έναντι της α1 και της β υπομονάδας του υποδοχέα, που απομονώθηκαν από τους συγκεκριμένους ορούς, έδειξαν πως τα αυτοαντισώματα ευθύνονται για δράση των ορών στους υποδοχείς των κυττάρων. Τόσο οι ολικοί οροί όσο και τα απομονωμένα-καθαρά αυτοαντισώματα έναντι των υπομονάδων α1 και β, προκάλεσαν δοσοεξαρτώμενη απώλεια υποδοχέων στα κύτταρα και μάλιστα τα αντι-α1 αντισώματα εμφανίστηκαν περίπου τέσσερις φορές δραστικότερα από τα αντι-β. Η ικανότητα των μερικώς απαλλαγμένων από αυτοαντισώματα έναντι του υποδοχέα ορών να προκαλούν απώλεια υποδοχέων στα κύτταρα, φάνηκε να ποικίλλει και να συσχετίζεται άμεσα με το είδος των αντισωμάτων που έχουν παραμείνει στον ορό, υποστηρίζοντας μια διαφορετικότητα στην παθογονικότητα των επιμέρους αντισωμικών κλασμάτων. Με σκοπό την επιβεβαίωση και ενίσχυση των αποτελεσμάτων που προκύπτουν από τα in vitro πειράματα, ακολούθησαν προσπάθειες για την πρόκληση πειραματικής μυασθένειας σε πειραματόζωα, με τη χορήγηση ορών μυασθενικών και καθαρών αυτοαντισωμάτων έναντι διαφόρων υπομονάδων του υποδοχέα. Η χορήγηση σε ζώα τόσο του ολικού ορού, όσο και καθαρών αντισωμάτων έναντι της α1-υπομονάδας του υποδοχέα, προκάλεσαν σημαντική απώλεια βάρους και εμφάνιση έντονων συμπτωμάτων μυϊκής αδυναμίας, μέχρι και το θάνατο. Πειραματόζωα που ενέθηκαν με το κλάσμα του ορού από το οποίο έχουν απομακρυνθεί τα συγκεκριμένα αντισώματα εμφάνισαν πολύ ηπιότερα ή και καθόλου συμπτώματα, ενώ απουσία συμπτωμάτων καταγράφηκε και κατά τη χορήγηση ορού που περιείχε αποκλειστικά αντισώματα έναντι της β υπομονάδας, αλλά και απομονωμένων αντι-β αντισωμάτων. Η παρούσα μελέτη υπέδειξε τα αυτοαντισώματα έναντι του AChR ως τον μοναδικό παθογόνο παράγοντα στον ορό μυασθενικών ατόμων, συμβάλλοντας στην κατανόηση της παθοφυσιολογίας της νόσου. Επιβεβαίωσε την υπεροχή των αντι-α1 αντισωμάτων έναντι των αντι-β, ως πρός την παθογονικότητά τους, τόσο in vitro όσο και in vivo, με την επιφύλαξη βέβαια που επιβάλλει ο μικρός αριθμός δειγμάτων που μελετήθηκαν. Η δυνατότητα λήψης αντισωμάτων που στοχεύουν σε συγκεκριμένη υπομονάδα μπορεί να συμβάλλει στη λεπτομερή μελέτη της δραστικότητας του κλάσματος και να οδηγήσει στη συσχέτισή του με την εμφάνιση συγκεκριμένων συμπτωμάτων της νόσου. / Acetylcholine receptors (AChRs) are integral membrane proteins that respond to the binding of acetylcholine (ACh), which is synthesized, stored and finally released by cholinergic neurons. Like other transmembrane receptors, AChRs have been classified according to either their pharmacological properties or their relative affinities for various molecules, and can therefore be further divided into: i) nicotinic AChRs, which are particularly responsive to nicotine and ii) muscarinic AChRs, which are particularly responsive to muscarine. AChRs are involved in myasthenia gravis (MG) and many other physiological disorders, mainly affecting the central and peripheral nervous system. In MG, autoantibodies are directed against the nicotinic AChR at the neuromuscular junction. The disease is characterized by various symptoms, including muscle weakness and fatigability, due to defective neuromuscular transmission. To obtain an insight into the role of the various anti-AChR antibody specificities in MG, we isolated and studied the in vitro and in vivo activity of autoantibodies targeting individual AChR subunits. Using recombinant proteins corresponding to extracellular domains (ECDs) of individual AChR subunits as immunoadsorbents; we isolated autoantibodies which specifically bind to these subunits. We then used the well established TE671 human muscle cell line to examine the in vitro functions of subunit-specific autoantibody populations through their ability to induce nAChR antigenic modulation. Isolated subunit-specific autoantibodies were also used to determine their capacity to passively transfer experimental MG into lab animals. Our results clearly demonstrated that autoantibodies against the α1 or β subunit can cause AChR loss via antigenic modulation in a dose-dependent manner, the anti-α1 autoantibodies being much more effective than the anti-β autoantibodies. Furthermore, we showed that the autoantibody-depleted sera were much less effective, or were completely inactive, at causing AChR loss. In in vivo experiments, the administration of MG sera derivatives to lab animals showed that sera enriched in anti-α1 autoantibodies, as well as the corresponding pure anti-α1 autoantibodies from two individuals, are efficient in inducing MG like symptoms to the animals. A single serum contained almost 100% anti-β antibodies and the corresponding purified antibodies did not cause any clinical MG symptoms. The depleted fraction of MG sera tested, induced mild symptoms or no symptoms were observed, and this is in agreement with the in vitro results, strongly suggesting that the anti-AChR autoantibodies in MG sera and mainly the anti-α1 specificities are the sole pathogenic factor in anti-AChR antibody-seropositive MG.