Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Description based on contents viewed Feb. 10, 2009; title from PDF t.p. Includes bibliographical references (p. 35-36).

Thesis (Ph. D.)--University of Toronto, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Nebraska Medical Center, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Toronto, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Nebraska Medical Center, 1999. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Les IL-36α, β et γ sont des cytokines appartenant à la famille de l’IL-1. Elles sont exprimées notamment dans la peau et sont impliquées dans la pathogenèse du psoriasis. Leurs inhibiteurs connus ou hypothétiques l’IL-36Ra et l’IL-38 agissent en limitant l’inflammation. Dans la polyarthrite rhumatoïde (PR) et la maladie de Crohn, l’expression et le rôle de ces cytokines sont encore débattues. Les travaux de cette thèse se consacrent à l’étude du profil d’expression des IL-36 et de leurs inhibiteurs ainsi qu’à déterminer l’impact d’une surexpression de l’IL-38 in vivo et in vitro. La première étude a été réalisée chez les patients atteints de PR en comparaison avec les patients psoriasiques et ceux atteints de maladie de Crohn ainsi que dans les modèles murins correspondants. Cette étude a montré que ces cytokines étaient exprimées majoritairement par les kératinocytes et les macrophages mais possédaient cependant des profils d’expression distincts. Elle a également permis d’identifier un sous-groupe de patients pour lesquelles les IL-36 pourraient avoir un rôle important et pourraient représenter une cible en clinique. La seconde partie de la thèse a permis de montrer un effet anti-inflammatoire d’une surexpression de l’inhibiteur IL-38 dans différents modèles d’arthrite in vivo et dans des macrophages in vitro. Les thérapies basées sur l’inhibition de cytokines ont déjà prouvé leur efficacité en clinique et sont une cible thérapeutique très prometteuse. Cette thèse a pour objectifs d’une part de mieux comprendre la biologie des nouvelles cytokines de la famille de l’IL-1 et d’autre part de participer à la découverte de nouvelles cibles thérapeutiques dans les pathologies inflammatoires chroniques telles que la PR. / IL-36α, β and γ are cytokines belonging to the IL-1 family. IL- 36 are expressed especially in the skin and are involved in the pathogenesis of psoriasis. Their inhibitors (well-known or hypothetical) IL-36Ra and IL-38 act in reducing inflammation. In rheumatoid arthritis (RA) and Crohn's disease, the expression and role of these cytokines need to be elucidated. This thesis is dedicated to the study of IL-36 agonists and antagonists expression profile and the better understanding of in vivo and in vitro impact of IL-38 overexpression. The firts study was conducted in patients with RA in comparison with psoriasis and Crohn's disease patients as well as in the corresponding relevant murine models. This study showed that these cytokines were expressed predominantly by keratinocytes and macrophages but had distinct expression profiles. A subgroup of patients for which the IL-36 could have an important role and may represent a clinical target was also identified. In the second part of the thesis, we demonstrated an anti-inflammatory effect following overexpression of the inhibitor IL-38 in several in vivo arthritis models and in macrophages in vitro. Cytokine neutralization based therapies have already proven effective in the clinic and are still a promising therapeutic target. This thesis aims firstly to better understand the biology of new IL-1 family cytokines and also to participate in the discovery of new therapeutic targets in chronic inflammatory diseases such as RA.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg for the degree of Master of Science / The antiinflammatory effects of lnterleukin-4 (IL-4) and the synthetic glucocorticoid dexamethasone were studied in adhered monocytes and the leukaemic cells HL-60 and THP-1, with respect to the expression of interleukin-l.B (IL-l.B), the (signalling) IL-l receptor type I (JL..IRtI), and the (inhibitory) JT_,.l receptor type n (IL-lRtII). (Abbreviation abstract) / AC 2018

Cytokines activate cell surface receptors to control and regulate immunity and hematopoiesis. Despite its enormous potential, pharmaceutical use of cytokines is in most cases hampered by their pleiotropic functionality, which renders cytokine-based therapies exceptionally difficult to control. Although there is growing evidence that the functional plasticity of cytokine receptors is largely encoded in the spatiotemporal dynamics of receptor complexes, no mechanistic correlation has hitherto been achieved. Two related aspects, the spatiotemporal organization and the activation mechanism of cytokine receptors in the plasma membrane, have further remained a topic of intensive and controversial debate. To shed to light into the mechanistic principles responsible for functional selectivity, this thesis aimed to quantitatively explore the molecular and cellular determinants governing cytokine receptor assembly and signaling using the type II interleukin-4 (IL-4) receptor as model system. To this end, by taking advantage of IL-4 and interleukin 13 (IL-13) agonists binding the receptor subunits IL-4Rα and IL-13Rα1 with different affinities and rate constants, an in vitro kinetic characterization of the receptor system was combined with live cell microscopy on the single molecule level and flow cytometry as well as in silico modeling approaches. The quantification of kinetics by a dedicated solid-phase detection method with the extracellular receptor domains tethered onto artificial membranes confirmed that the affinity and stability of the two-dimensional molecular interactions determine receptor dimerization levels and dynamics. Single molecule localization microscopy at physiological cell surface expression levels, however, revealed efficient ligand-induced receptor dimerization, largely independent of the two-dimensional receptor binding affinities, in line with similar STAT6 activation potencies observed for different IL-4 variants. Detailed spatiotemporal analyses and single molecule co-tracking of receptor subunits and ligands in conjunction with spatial-stochastic modeling identified confinement by actin-dependent membrane micro-compartments as an important cellular determinant for sustaining transient receptor dimers. By correlating downstream cellular responses with various three-dimensional binding affinities and kinetics of engineered IL-13 variants, distinct roles of ligand association and dissociation kinetics were uncovered. Whereas the extent of membrane-proximal effector activation is dependent on the association rate by controlling the number of formed receptor complexes in the plasma membrane, the lifetime of receptor complexes determines the potency of a ligand for inducing more distal responses and is, due to accumulation of signaling complexes in endosomes, directly connected to the kinetics of early signaling events.

Cyclosporine is a potent immunosuppressive agent used to treat a wide range of canine inflammatory diseases. Unfortunately, optimal dosing protocols for achieving immunosuppression with cyclosporine in dogs remain unclear, and standard methods that objectively monitor effectiveness of immunosuppression have not been established. We evaluated an already established panel of biomarkers of immunosuppression in vivo with two oral dosages of cyclosporine in seven normal dogs, a high dosage known to induce immunosuppression and a lower dosage used to treat atopy, with a washout period between the two dosages. The biomarker panel included the flow cytometric evaluation of T-lymphocyte cytokine expression (IL-2, IL-4, and IFN-gamma). High dosage cyclosporine resulted in significant decreases in IL-2 and INF-gamma expression, but not IL-4 expression. Low dosage cyclosporine was associated with a significant decrease in INF-gamma expression, while IL-2 expression was not affected. The results demonstrated suppression of biomarkers in a dose-dependent manner.

Endotoxemia is responsible for severe illness in horses. Individuals can become unresponsive to the endotoxin molecule after an initial exposure; this phenomenon has been called developing a state of "endotoxin tolerance" (ET). ET has been induced in horses in vivo; however, cytokine expression associated with ET has not been investigated. The purpose of this study was to develop and validate a method for inducing ET in equine peripheral blood mononuclear cells (PBMCs) in vitro, and to describe the cytokine profile which is associated with the ET. Blood was collected from 6 healthy horses and PBMCs were isolated. ET was induced by culturing cells with three concentrations of endotoxin given to induce ET, and evaluated after a second dose of endotoxin given to challenge the cells. The relative mRNA expression of IL-10 and IL-12 was measured by use of quantitative PCR. ET was induced in all cells (n=6) exposed to the 2-step endotoxin challenge. In PBMCs treated with 1.0 ng/ml of endotoxin followed by challenge with 10 ng/ml of endotoxin, the relative mRNA expression of IL-10 in tolerized cells was not different from positive control cells. In contrast, the relative mRNA expression of IL-12 in tolerized cells was decreased by 15-fold after the second endotoxin challenge compared with positive control cells. This experiment demonstrated a reliable method for the ex vivo induction of ET in equine PBMCs. A marked suppression of IL-12 production is associated with ET. The production of IL-10 was not altered in ET in our model. / Master of Science