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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

En 1967, Philippa Foot formule une expérience de pensée tellement populaire qu'elle deviendra une véritable sous-discipline de l'éthique. Le dilemme du tramway et plusieurs de ses variantes permettent de formuler et d'illustrer plusieurs critiques à l'encontre d'une théorie normative importante, l'utilitarisme. Ces critiques peuvent être regroupées sous deux problèmes principaux : le sacrifice des autres et le sacrifice de soi. Les partisans de l'utilitarisme répondent néanmoins à ces critiques de plusieurs façons. Certains soutiennent que des erreurs d'interprétations de la théorie utilitariste sont à l'origine des critiques. D'autres rejettent les intuitions à la base de ces problèmes. Finalement, certains profitent des critiques pour développer une variante de l'utilitarisme qui répond aux commentaires. Nous soutenons dans le mémoire qu'aucune de ces stratégies ne constitue une réponse finale aux critiques soulevées.

Asthma is a common chronic respiratory disease where patients suffer from restricted airways and airway inflammation (mainly eosinophilic type 2 (T2) inflammation). Inhaled (ICS)/oral corticosteroids (OCS) and, more recently T2-targeting biologics, are prescribed as mainstay therapies for asthma. Despite these therapies, a subset of asthma patients continues to have symptoms and airway inflammation, suggesting an underlying additional asthma pathology. We have observed multiple airway autoantibodies in 55% of moderate-to-severe asthma patients associated with inadequate response to corticosteroids and anti-T2 biologics. Increased airway degranulation (eosinophilic and/or infective) together with lymphopenia (low lymphocyte counts) underlie these self-reactive/autoimmune-like events. In healthy individuals, regulatory lymphocytes limit the development and activity of self-reactive cells, including those capable of producing autoantibodies. Lymphopenia can lead to skewed non-regulatory to regulatory lymphocyte subsets that support a microenvironment with reduced ability to limit self-reactivity. In this study, wanted to measure B cell subsets by flow cytometry and non-regulatory to regulatory B cell ratios in asthma patients and healthy controls. To understand B cell compartmentalization, we analyzed peripheral and sputum B cells. We identified decreased regulatory B cells (Bregs), in particular CD5+ Bregs, and skewed non-regulatory to regulatory B cell ratios in both circulation and airways of asthma patients. Compared to healthy controls, only patients requiring daily OCS had significantly lower CD5+ Bregs, suggesting a reduced regulatory component in more severe patients. Further, CD5+ Bregs, capable of producing immunomodulatory interleukin-10, were significantly lower in patients with a history of multiple lymphopenic events (70% requiring daily OCS). Together, this supports the need to investigate lymphopenia-induced dysregulation of Bregs, increase in autoreactive B cells and airway autoreactivities, and subsequent progression into a more-severe therapy refractory autoimmune pathology. This opens a new avenue for asthma treatment, particularly for the severe population with airway autoimmune responses often not targeted/controlled by current anti-inflammatory therapies. / Thesis / Master of Science (MSc) / Asthma is a common respiratory disease where patients have difficulty breathing and airway inflammation. Corticosteroids and/or targeting biologic therapies are prescribed to reduce inflammation. Despite these treatments, some patients still have inflammation. In patients that don’t respond well to treatment, we have found evidence of self-attacking antibodies that can further lead to disease severity. These antibodies are produced by self-attacking B cells normally suppressed by regulatory B cells (Bregs). We wanted to measure if asthma patients have reduced ability to limit self-attacking B cells because of reduced Bregs. We found that asthma patients have lower Bregs and an imbalance of non-regulatory to regulatory B cells in the blood and airways. Together, we show B cell subsets that suggest a self-attacking asthma component, not targeted by current asthma treatments. Understanding the involvement of Bregs in asthma opens a new therapeutic option in those that don’t respond well to current treatment.

DKD is the leading cause of kidney failure in Canada and its patients suffer the highest morbidity and mortality rates of any kidney failure patient group. Current interventions including strict glycemic control only delay DKD. Thus, there is a major need to identify new therapeutic targets. High glucose (HG) is identified as a major pathogenic factor, inducing the release of growth factors leading to kidney fibrosis. Although treatments have been developed to target these factors, their effectiveness is accompanied by adverse effects due to the lack of specificity. Recently, activins have been suggested to have a prominent role in promoting renal fibrosis and developing a specific anti-activin therapy can avoid potential side effects. Although there is evidence supporting an important role for activin A (ActA) in the induction of fibrosis in DKD, whether ActB also contributes is unknown. In this study, we aim to determine the potential contribution of ActB to promoting fibrosis. Our results show that ActA and ActB are upregulated in rodent and human DKD. We show that hyperglycemia leads to the secretion of ActA and ActB by mesangial cells (MC), whereas only ActB is secreted by renal fibroblasts (RF). Similar to HG, treatment with ActA or ActB leads to Smad2/3 activation and upregulation of extracellular matrix proteins, whereas specific inhibition of either ActA or ActB attenuates these effects. We show that ActA and ActB regulate HG-induced activation of MRTF-A/SRF in MC, leading to an activated phenotype characterized by increased α-SMA expression and ECM production. Lastly, we confirm the specificity and functionality of the activin propeptides in vitro, providing evidence for their effectiveness in vivo. This study will help further our knowledge of the role activins in DKD, potentially providing an alternative therapy. / Thesis / Master of Science (MSc) / As the leading cause of end stage renal disease, diabetic kidney disease (DKD) is described as the reduction in renal function due to chronic exposure to diabetes. This thesis is aimed to understand the pathways and mechanisms that contribute to the development and progression of DKD to help identify novel therapeutic options. This project identified activin B (ActB) as a contributor to the disease and gives evidence that blocking the actions of ActB can prevent profibrotic effects in cells, similar to the profibrotic effects seen in DKD. Furthermore, this thesis demonstrates preliminary evidence for the beneficial effects of anti-ActB therapy, providing a potential alternative therapeutic option for DKD patients.

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No description available.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Problem: Herpes simplex virus type-2 (HSV-2) is one of the most prevalent sexually transmitted infections in the world, and rates of infection are higher in women compared to men. Furthermore, vaccines developed against HSV-2 have failed at various stages of clinical trials, due to their inability to induce protective mucosal immunity. In animal models, intranasal (IN) immunization with attenuated HSV-2 (TK−) virus has been shown to confer protection against wildtype HSV-2 challenge. Since IN immunization serves as a more practical and less intrusive vaccination strategy, further studies are warranted to characterize optimal immune responses following IN immunization. We have previously demonstrated that estradiol (E2) treatment promotes enhanced protection against HSV-2 through enhanced anti-viral T cells responses. However, the effect of E2 on B cell responses, which were recently shown to be critical in protecting the host following IN immunization, remain poorly understood. Therefore, in this study we aimed to examine if following IN immunization, E2 enhances the memory B cell (MBC) and antibody-secreting plasma cell populations within the secondary lymphoid tissues and nasal effector sites, and whether this enhancement leads to an overall better protection against intravaginal IVAG WT-HSV-2 challenge. Methodology: Ovariectomized (OVX) mouse model of HSV-2 were pre-treated with E2 or placebo pellets. Subsequently, both groups were immunized intranasally with TK- HSV-2. Four weeks later nasal associated lymphoid tissues, nasal mucosa, cervical and iliac lymph nodes, spleen and vaginal tract were collected and processed and MBC and antibody-secreting plasma cells were characterized by flow cytometric analysis. HSV-2 specific IgM and IgG antibody responses in serum and vaginal secretions were measured by ELISA. In parallel experiments, animals were IVAG challenged with WT-HSV-2 and the B cell subsets were characterized as above. Results: The formation of MBC subsets, as seen by the presence of CD19+ IgD- cells and the heterogenous expression of CD73, CD80, and PD-L2, were observed four-weeks post immunization within the cervical and iliac lymph nodes and spleen, which were further enhanced in the presence of E2. Additionally, E2-treated mice had increased number of B220- CD138+ IgG2c+ plasma cells within the nasal mucosa following immunization. These enhancements translated into increased levels of HSV-2 specific IgG2b and IgG2c antibodies within the serum and vaginal secretions of E2-treated mice at four-weeks post IN immunization. Upon IVAG challenge, E2-treated mice, but not control mice, were protected. Since the antibody isotypes that were enhanced in E2 treated mice are correlated with Th17 responses, E2 mediated antibody enhancement was tested in IL-17 knockout mice. E2 treatment in IL-17-knockout mice failed to induce similar responses observed in WT mice, indicating that the enhancement of B cells and antibodies seen following E2 treatment was mediated in an IL-17 dependent manner. Conclusion: This study highlights the importance of sex-dependent differences in vaccine-induced immunity. Specifically, the findings from this study will provide valuable information for the design of a potentially efficacious mucosal vaccine strategy, whereby immunization in the context of E2 could significantly enhance antigen-specific antibody responses in the genital tract. / Thesis / Master of Science (MSc)

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