Στην παρούσα εργασία μελετάται η κυτταρική ανοσοαπόκριση σε ασθενείς με ιδιοπαθή θρομβοπενική πορφύρα. Αναλυτικότερα εξετάζονται οι επιμέρους υποπληθυσμοί λεμφοκυττάρων και οι κυτταροκινές που αυτά εκκρίνουν με την τεχνολογία της κυτταρομετρίας ροής. Ιδιαίτερη έμφαση έχει δοθεί στον υποπληθυσμό των ρυθμιστικών των λεμφοκυττάρων / In the present study we examine the immune response in patients with immune thrombocytopenic purrura. Using flow cytometry we examined the subpopulation of lymphocytes and cytokines they produce. We also examined the subpopulation of regulatory the cells who seems to play a crucial role in autoimmunity.

This thesis investigates the relationship between quantitative correlates of diffuse brain damage and neurological and psychiatric manifestations in Systemic Lupus Erythematosus (SLE). A group of 37 patients with a primary diagnosis of SLE (mean age 43.97±12.SS) were compared to 29 matched healthy controls. The SLE group were subdivided into those who had experienced neuropsychiatric (NP) manifestations (NPSLE - n=lS) and those who had never had NP manifestations (non-NPSLE). Participants completed a broad cognitive test battery, neuropsychological measures and quantitative MRI (magnetisation transfer (MTI) and diffusion tensor imaging (OTI)). From MTI the magnetisation transfer ratio (MTR) was measured, which can be a marker for demyelination. Using OTI the extent (apparent diffusion coefficient) and directionality (fractional anisotropy) of diffusion were assessed, which are sensitive measures of brain structural integrity. Results indicate that both SLE groups had significantly higher scores on depression and anxiety and lower quality of life compared to healthy controls. The only difference between the NPSLE and non-NPSLE groups was lower physical health related quality of life in the former group. On cognitive tasks the NPSLE group scored significantly worse than controls on multiple domains, and worse than the non-NPSLE group on memory and speed of processing. There were no differences between the non-NPSLE patients and controls. On OTI measures the NPSLE group showed increased white matter ADC and a non significant decrease in FA, changes which are consistent with subtle brain damage in this group. The non-NPSLE group had higher ADC than controls if measured in the whole brain. There were no differences on MTI and few differences on measures of brain volume, suggesting demyelination and atrophy were not noteworthy in this cohort. Correlations were assessed between cognition and the other factors. In the NPSLE group cognitive function correlated with white matter FA suggesting this was driven by changes in brain parenchyma. Cognitive function also correlated with pain, fatigue, physical health, disease activity and anxiety scores suggesting general health related factors also play a role in cognitive dysfunction. In the non-NPSLE group processing speed correlated with depression scores, but no other relationships were evident. The role of anti-phospholipid antibodies, anti- Ro antibodies, corticosteroid dose and confounds such as renal involvement in SLE, hypertension and motor speed differences were considered. None of these factors could explain cognitive dysfunction in the patient group. These findings are interpreted as indicating that cognitive performance in NPSLE is unlikely to be driven by emotional health. Instead performance related to white matter integrity and general illness, two factors which may be interlinked.

Background: Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease characterised by autoantibody production and variable clinical features, ranging from mild to severe disease. Patients with SLE are at increased risk of developing accelerated atherosclerosis. Biomarkers have potential utility in SLE as markers of disease or predictors of future clinical events and mortality. Objective The aim of this thesis was to identify serological biomarkers predictive for erosive arthritis (EA), cardiovascular events (CVEs), mortality and subclinical atherosclerosis in SLE. Methods: In chapters 2 to 4, study subjects were SLE patients from Bath. Anti-cyclic citrullinated peptide antibodies (ACPA) and HLA-DR and -DQ were studied for markers of EA, and anticardiolipin (aCL) and lipoprotein profiles for markers of CVEs and mortality. In chapters 5 and 6, study subjects were women with SLE from Manchester. B-mode ultrasound scans of subjects' carotid arteries were performed at baseline and follow-up time-points to detect atherosclerotic plaque. Baseline IgG and IgM antiphospholipid (aPL) antibodies and CV risk factors were studied for markers of subclinical atherosclerosis. Clinical data collected for all studies included SLE features and auto-antibody profiles. Results: ACPA was identified as a marker of a SLE phenotype with EA - "rhupus". Patients with major erosive arthritis were HLA-DQB1*0302 carriers. Increased aCL GPL levels and total cholesterol : high density lipoprotein-C (TC : HDL-C) ratio were markers for future CVEs, and increased TC : HDL ratio, aCL GPL and lipoprotein(a) concentrations were markers for increased mortality. Lower HDL-C concentrations and anti-annexin A5 (anti-AnxA5) GPL were markers of carotid plaque progression. Conclusion: This thesis identified new markers for EA, subclinical atherosclerosis and future CVE and mortality risk in SLE. Strategies to incorporate these new CV markers into clinical CV risk assessments may assist in distinguishing the subset of SLE patients most at risk of developing accelerated atherosclerosis.

Η παρούσα διατριβή είχε ως στόχο τη μελέτη των Th1 και Th2 τύπου κυτταροκινών σε αυτοάνοσες νόσους και τη διερεύνηση του τρόπου με τον οποίο η έκφρασή τους επηρεάζεται από παράγοντες όπως πεπτιδικά ανάλογα της βασικής πρωτείνης της μυελίνης και ανοσοτροποποιητικοί παράγοντες όπως το μόριο της λεπτίνης. Η μελέτη αυτών των παραγόντων εστιάστηκε στη νόσο της Σκλήρυνσης Κατά Πλάκας, επειδή πρόκειται για οργανοειδικό CD4+ Τ κυτταρομεσολαβούμενο αυτοάνοσο νόσημα με χαρακτηριστικό Th1 κυτταροκινικό προφίλ. Αυτά τα χαρακτηριστικά, σε συνδυασμό με το γεγονός ότι διαθέτει το καλύτερα μελετημένο αντίστοιχο ζωικό μοντέλο, την Επαγόμενη Αλλεργική Εγκεφαλομυελίτιδα, καθιστούν τη νόσο αυτή ένα ιδανικό πειραματικό σύστημα για την επίτευξη του στόχου της παρούσας εργασίας. / -

Le syndrome des anticorps antiphospholipides (SAPL) est caractérisé par une atteinte auto-immune systémique à l’origine d’événements cliniques thrombotiques ou obstétricaux en présence d’anticorps antiphospholipides (aPL) persistants sur 2 prélèvements. Ce travail de thèse s’est intéressé à des manifestations cliniques et des tests biologiques dont le but est d’évaluer le risque thrombotique dans ce syndrome. En premier lieu, le risque de valvulopathie associé aux aPL chez les patients lupiques a été étudié. L’existence d’une telle association faisait l’objet d’une controverse non résolue. En ayant recours à une revue systématique de la littérature et à une méta-analyse d’études observationnelles, les fréquences des valvulopathies chez les patients lupiques en fonction de la présence ou non d’aPL ont été comparées. Le résultat principal est, qu’en présence d’aPL chez les patients lupiques, ce risque est multiplié par 3. En second lieu, la valeur pronostique sur le risque de thrombose des thromboses veineuses superficielles (TVS) a été étudiée chez les patients atteints d’un SAPL. Une étude de cohorte prospective monocentrique a montré que la présence d’un antécédent de TVS était prédictive du risque de thrombose ultérieure. D’autre part, l’apport de nouveaux marqueurs biologiques, les anticorps spécifiquement dirigés contre le domaine I de la [bêta]2-Glycoprotéine I ainsi que les paramètres de thrombinographie prenant en compte la sensibilité à la protéine C activée ont été étudiés. Les résultats montrent que ces 2 tests sont prédictifs du risque thrombotique incident. Enfin, les données de qualité de vie d’une cohorte multicentrique de patients atteints de lupus et/ou porteurs d’aPL, ont été analysées. Les résultats montrent que la présence d’un antécédent de thrombose artérielle était associée à une altération de toutes les dimensions de la qualité de vie évaluée par un auto-questionnaire généraliste (MOS-SF36) en comparaison à des patients atteints de maladie auto-immune sans ce type de thrombose. Ces résultats pourront avoir un impact significatif dans la réflexion sur l’évolution des critères de classification de ce syndrome / Antiphospholipid syndrome (APS) is characterized by an auto-immune disorder with thrombotic and obstetrical morbidity in the presence of persistant antiphospholipid antibodies (aPL). This work studied clinical manifestations and laboratory assays for the determination of thrombotic risk in APS patients. Firstly, the risk of heart valve disease associated with aPL in systemic lupus erythematosus (SLE) patients was studied. Since 20 years, data regarding this association yielded conflicting results. A systematic review and a meta-analysis were performed to compare frequencies of heart valve disease in SLE patients with and without aPL. Main result concluded that the presence of aPL in SLE patients is associated with a 3-fold increased risk for heart valve disease in comparison with SLE patients without these antibodies. Secondly, prognostic significance of superficial vein thrombosis (SVT) was studied in APS patients. A prospective cohort study was performed and showed that SVT was predictive of thrombotic events overtime in this population. Moreover, the contribution of new laboratory assays were studied (antibodies directed against the domain I of [beta]2-Glycoprotein I and thrombin generation assay assessing sensitivity to activated protein C). Results demonstrated that these two assays were predictive of thrombotic events in APS patients. Finally, health-related quality of life was assessed in a multicentric cohort study of patients with aPL and/or SLE. Results showed that the presence of a history of arterial thrombosis was significantly associated with an impairment of all dimensions scores assessed by the MOS-SF36 questionnaire in comparison with patients with an auto-immune disease but without arterial thrombosis. This work provides new insights in the field of APS and may have an impact in the evolution leading to new classification criteria for definite APS.

The Major Histocompatibility Complex (MHC) is a genomic region in chromosome 6 which has been consistently found to be associated with the risk of developing virtually all common autoimmune diseases. Although its importance in disease pathogenesis has been known for decades, efforts to disentangle the roles of the classical human leukocyte antigens (HLA) and other variants responsible for the susceptibility to disease have often met with limited success, owing to the complex structure and extreme heterogeneity of the region. In this thesis, I interrogate the MHC for association with three common autoimmune diseases, ankylosing spondylitis, psoriasis and multiple sclerosis, with the aim of confirming the previously-reported associations and of identifying novel ones. To do so, I employ a systematic, joint analysis of single nucleotide polymorphism (SNP) and HLA allele data, in a logistic regression framework, using a recently developed algorithm to predict the HLA alleles for samples where such information is unavailable. To ensure the reliability of the analysis, I apply stringent quality control procedures and integrate over the uncertainty of the HLA allele predictions. Moreover, I resolve the haplotype phase of individuals from the HapMap project to create reliable reference panels, used in both HLA prediction and in quality control procedures. By directly testing HLA subtypes for association with the disease, the power to detect such associations is increased. I present the results of the analysis on the three disease phenotypes and discuss the evidence for important novel findings amongst both SNPs and HLA alleles in two of the diseases. In the final part of this thesis, I introduce a novel, model-based approach to detect inconsistencies in the data and show how it can be used to flag problematic SNPs which conventional quality control procedures may fail to identify.