<p>Within the field of immunology, the existence of autoimmune diseases presents a unique set of challenges. The immune system typically protects the host by identifying foreign pathogens and mounting an appropriate response to eliminate them. Great strides have been made in understanding how foreign pathogens are identified and responded to, leading to the development of powerful immunological tools, such as vaccines and a myriad of models used to study infectious diseases and processes. However, it is occasionally possible for host tissues themselves to be inappropriately identified as foreign, prompting an immune response that attempts to eliminate the host tissue. The immune system has processes in place, referred to as selection, designed to prevent the development of cells capable of recognizing the self as foreign. While a great deal of work has been invested in understanding these processes, many concrete answers remain elusive. </p><p>Our laboratory, which focuses on understanding the roles of E and Id proteins in lymphocyte development, has established the Id3 knockout mouse as a model of autoimmune disease. Id3 knockout mice develop a disease reminiscent of human Sj&#1255;gren's Syndrome, an autoimmune disease that progressively damages the salivary and lachrymal glands. Continued study of this model has yielded interesting results. These include the identification of CD4+ T cells as initiators of disease as well as the identification of the cytokine Interleukin 13 (IL-13) as a potential causative agent. However, the source of IL-13, its true role as a causative agent of disease, as well as the developmental basis for its elevated expression remained elusive. </p><p>To this end, I utilized a reporter gene that enabled me to detect cells producing IL-13 as well as test the effects of IL-13 deletion on disease progression. Using this system, I was able to identify both CD4+ T cells and &#947;&#948; T cells as major sources of IL-13. I was also able to determine that elimination of IL-13 in Id3 knockout mice was sufficient to block the development of disease symptoms, reinforcing the hypothesis that IL-13 is a causative agent in disease initiation. Finally, I attempted to better characterize the phenotype of cells producing IL-13. These experiments indicated that the T cell receptor (TCR) repertoire of Id3 knockout mice is markedly different than that of wild-type (WT) mice. Furthermore, cells bearing certain TCRs appeared to express IL-13 at dramatically different rates, indicating that certain TCRs may be predisposed to IL-13 particular effector fates.</p> / Dissertation

Introduction: Asthma is a disease that occurs worldwide and approximately 300 million people carry this disease. It is characterized by chronic inflammation, airway obstruction and airway hyper-responsiveness (AHR). This T-lymphocyte controlled disease has symptoms such as coughing, wheezing, and chest tightness. In addition to chronic inflammation, asthma is also caused by overproduction of mucus and airway wall remodelling. The chronic inflammation and airway wall remodelling are suggested to contribute to the AHR and airway obstruction. AHR is a way to measure the reactivity in the airways in asthmatics. IL-13 has been shown to play an important role in the development of AHR, and biopsies from bronchial submucosa and air way smooth muscle (ASM) in humans have shown an increased concentration of IL-13 in severe asthma. Aim: The aim of this work was to evaluate if IL-13 is able to enhance the 5-HT response in mouse tracheal segments, which had been cultured for 2 days and, if so, try to unravel the underlying mechanism for this phenomenon. Literature reports that IL-13 enhanced contractions in mouse trachea in presence of KCl and CCH. Earlier work within this project did not find any clear proof for this observation. However, in this work this observation will be evaluated in a more controlled fashion by correcting for size and location of the trachea. Methods: The trachea was removed from Balp/c mice and cultured in small wells for two days in DMEM medium and various additions were performed to the medium for understanding the effect of e.g. IL-13 on the cells. The contractility change due to IL-13 and various additions in segments challenged with KCL, CCH and 5-HT were measured in a tissue-organ bath. Results and Conclusion: A more enhanced CCH induced contraction of IL-13 treated segments was obtained for the lower part compared to the upper part of the trachea. IL-13 enhanced the response in the ASM to 5-HT after two days of culturing. An increased concentration of the cytokine IL-13 in the airways from TH2-cells enhances the reactivity to 5-HT in the ASM. The underlying mechanism might involve JNK and ERK but more experiments are needed to statistically ensure this claim.

While numerous studies have linked family routines to pediatric asthma outcomes, it remains unclear how family routines come to be associated with these outcomes on a biological level. The current study investigated whether longitudinal trajectories of inflammatory markers of asthma could be predicted by levels of family routines in youth with asthma. Family routines were assessed at baseline through parent questionnaires and peripheral blood samples obtained from youth every 6 months (total number of assessments = 4) over the course of an 18 month study period. Youth with more family routines in their home environment showed decreases in mitogen-stimulated production of a cytokine implicated in asthma, IL-13, over the course of the study period. In turn, within-person analyses indicated that at times when stimulated production of IL-13 was high, asthma symptoms were also high, pointing to the clinical relevance of changes in IL-13 over time. A variety of potential explanations for this effect were probed. Parental depression, stress, and general family functioning could not explain these effects, suggesting that family routines are not just a proxy for parent psychological traits or family relationship quality. However, medication use eliminated the relationship between family routines and stimulated production of IL-13. This suggests that family routines do impact asthma outcomes at the biological level, possibly through influencing medication adherence. Considering daily family behaviors when treating asthma may help improve both biological and clinical profiles in youth with asthma.

While numerous studies have linked family routines to pediatric asthma outcomes, it remains unclear how family routines come to be associated with these outcomes on a biological level. The current study investigated whether longitudinal trajectories of inflammatory markers of asthma could be predicted by levels of family routines in youth with asthma. Family routines were assessed at baseline through parent questionnaires and peripheral blood samples obtained from youth every 6 months (total number of assessments = 4) over the course of an 18 month study period. Youth with more family routines in their home environment showed decreases in mitogen-stimulated production of a cytokine implicated in asthma, IL-13, over the course of the study period. In turn, within-person analyses indicated that at times when stimulated production of IL-13 was high, asthma symptoms were also high, pointing to the clinical relevance of changes in IL-13 over time. A variety of potential explanations for this effect were probed. Parental depression, stress, and general family functioning could not explain these effects, suggesting that family routines are not just a proxy for parent psychological traits or family relationship quality. However, medication use eliminated the relationship between family routines and stimulated production of IL-13. This suggests that family routines do impact asthma outcomes at the biological level, possibly through influencing medication adherence. Considering daily family behaviors when treating asthma may help improve both biological and clinical profiles in youth with asthma.

While numerous studies have linked family routines to pediatric asthma outcomes, it remains unclear how family routines come to be associated with these outcomes on a biological level. The current study investigated whether longitudinal trajectories of inflammatory markers of asthma could be predicted by levels of family routines in youth with asthma. Family routines were assessed at baseline through parent questionnaires and peripheral blood samples obtained from youth every 6 months (total number of assessments = 4) over the course of an 18 month study period. Youth with more family routines in their home environment showed decreases in mitogen-stimulated production of a cytokine implicated in asthma, IL-13, over the course of the study period. In turn, within-person analyses indicated that at times when stimulated production of IL-13 was high, asthma symptoms were also high, pointing to the clinical relevance of changes in IL-13 over time. A variety of potential explanations for this effect were probed. Parental depression, stress, and general family functioning could not explain these effects, suggesting that family routines are not just a proxy for parent psychological traits or family relationship quality. However, medication use eliminated the relationship between family routines and stimulated production of IL-13. This suggests that family routines do impact asthma outcomes at the biological level, possibly through influencing medication adherence. Considering daily family behaviors when treating asthma may help improve both biological and clinical profiles in youth with asthma. / Arts, Faculty of / Psychology, Department of / Graduate

Background: IL-4 and IL-13 are related cytokines with similar functional properties. Differential regulation of IL-4 and IL-13 has not been described. Objective: We have examined the effects of IFN-α on antigen-driven proliferation, IL-4 generation, and IL-13 generation from human PBMCs and T-cell clones. Methods: Proliferation was assessed by 3H-thymidine incorporation. Cytokine generation was assessed by reverse transcription PCR and ELISA. Messenger RNA stability was assessed in the presence of actinomycin D. Results: IFN-α induced a concentration-dependent inhibition of antigen-driven proliferation of TH1 and TH2 clones (median effective concentration, 150 to 200 U/mL); the sensitivity of TH1 and TH2 clones to IFN-α was not significantly different (P = .6). IFN-α induced an analogous concentration-dependent inhibition of antigen-driven IL-13 generation from TH1 and TH2 clones (median effective concentration, 100 U/mL); this effect was evident by 12 hours of culture and persisted beyond 48 hours. However, IL-4 generation from TH2 clones was insensitive to IFN-α at all concentrations and times tested (1 to 10,000 U/mL). A similar inhibitory effect of IFN-α on mitogen-driven proliferation and IL-13 generation from PBMCs was demonstrated; once again, IL-4 generation from PBMCs was insensitive to IFN-α. IL-13 mRNA stability was unaffected by IFN-α, suggesting transcriptional regulation. Conclusion: IFN-α differentially regulates antigen-stimulated IL-4 and IL-13 generation.

Interleukin-33 (IL-33) is a multifunctional cytokine that mediates local inflammation upon tissue damage. IL-33 is known to act on multiple cell types including group 2 innate lymphoid cells (ILC2s), Th2 cells, and mast cells to drive production of Th2 cytokines including IL-5 and IL-13. IL-33 signaling activity through transmembrane ST2L can be inhibited by soluble ST2 (sST2), which acts as a decoy receptor. Previous findings suggested that modulation of IL-13 levels in mice lacking decoy IL-13Rα2, or mice lacking IL-13, impacted responsiveness to IL-33. In this study, we used Il13-/- mice to investigate whether IL-13 regulates IL-33 activity by modulating the transmembrane and soluble forms of ST2. In Il13-/- mice, the effects of IL-33 administration were exacerbated relative to wild type (WT). Il13-/- mice administered IL-33 i.p. had heightened splenomegaly, more immune cells in the peritoneum including an expanded ST2L+ ILC2 population, increased eosinophilia in the spleen and peritoneum, and reduced sST2 in the circulation and peritoneum. In the spleen, lung, and liver of mice given IL-33, gene expression of both isoforms of ST2 was increased in Il13-/- mice relative to WT. Because IL-13 and IL-4 signal through a shared receptor complex IL-13Rα1/IL-4Rα, we also studied the combined deficiency of IL-4 and IL-13 using Il4rα-/- mice which are defective in both IL-4 and IL-13 signaling. Responses of Il4rα-/- mice were indistinguishable from those of Il13-/- mice in our model system of IL-33-induced inflammation, suggesting that IL-4 does not play a distinct role separate from IL-13 in regulation of IL-33 activity. Through in vitro experiments, we confirmed fibroblasts to be an IL-13-responsive cell type that can regulate IL-33 activity through production of sST2. This study elucidates the important regulatory activity that IL-13 exerts on IL-33 through induction of IL-33 decoy receptor sST2 and through modulation of ST2L+ ILC2s.

No description available.

Les prostaglandines sont de petites molécules qui jouent d'importants rôles immunomodulateurs au niveau du système immunitaire. Elles contribuent notamment à l'établissement de l'inflammation et à la résolution de celle-ci. La prostaglandine J 2 (15d-PGJ2 ) est d'ailleurs l'une des prostaglandines les plus étudiées en vertu de ses activités anti-inflammatoires. En effet, il a été démontré que celle-ci peut inhiber plusieurs molécules dont plusieurs cytokines et le facteur de transcription NF-?B. D'un autre côté, l'effet de la 15d-PGJ 2 sur l'interleukine-13 (IL-13) est encore inconnu à ce jour. L'IL-13 est une cytokine produite principalement par les cellules T et qui module plusieurs types de cellules immunitaires, tant au niveau de leur différentiation que de leur activation. De plus, cette cytokine contribue à l'établissement de certaines pathologies telles que l'asthme et la colite ulcéreuse lorsqu'elle est surexprimée. L'objectif principal de ce mémoire est de vérifier l'effet de la 15d-PGJ 2 sur l'expression et la production de l'IL-13 par les cellules T. Les résultats obtenus dans ce projet démontrent que la I 5d-PGJ2 inhibe la production de l'IL-13 par les cellules T. En effet, autant la lignée cellulaire de lymphocytes T CD4+ Jurkat E6.1 que les cellules mononucléaires circulant dans le sang (de l'anglais PBMCs ) stimulés par des agents mimant l'activation des cellules T tels que le PMA et la ionomycine, puis traités à la 15d-PGJ 2 ont montré une inhibition dans l'expression et la production de l'IL-13. Les résultats ont également révélé un effet similaire lorsque les cellules étaient pré-traitées à I 5d-PGJ2 , puis stimulées avec PMA/ionomycine. Par ailleurs, plusieurs éléments sont essentiels pour activer la transcription de l'IL-13, dont le facteur de transcription NF-?B. D'un autre côté, il est connu que la 15d-PGJ2 inhibe la cascade de signalisation de NF-?B. Ainsi, nous avons voulu vérifier si NF-?B était impliqué dans le mécanisme d'inhibition de l'IL-13 par la 15d-PGJ2 . Pour ce faire, des extraits nucléaires ont été réalisés avec les Jurkat E6.1 et les PBMCs traitées à la 15dPGJ2 puis un essai de retard sur gel (de l'anglais EMSA, Electromobility shift assay ) a été fait avec une sonde NF-?B consensus ou une sonde d'un site de liaison putatif de NF-?B dans le promoteur IL-13. Les résultats ont révélé que le facteur de transcription NF-?B était effectivement activé lors de la transcription de l'IL-13 et inhibé lors d'un traitement à la 15d-PGJ 2 . Par la suite, puisqu'il a déjà été démontré que la 15d-PGJ2 active le récepteur nucléaire PPAR-?, nous avons voulu vérifier si le mécanisme d'inhibition de l'IL-13 dépendait ou non de ce dernier. Un antagoniste irréversible de PPAR-? a donc été utilisé dans les expériences, et l'essai a permis d'établir que le mécanisme d'inhibition de l'IL-13 parla 15d-PGJ 2 était indépendant de PPAR-?. Finalement, ces résultats dévoilent que la 15d-PGJ 2 inhibe l'expression et la production de l'IL-13, que cet effet serait indépendant de PPAR-?, et qu'il impliquerait probablement une inhibition du facteur de transcription NF-xB. Ces résultats pourraient avoir des implications cliniques où l'IL-13 joue un rôle d'importance, tels que l'asthme et la colite ulcéreuse. L'utilisation de cette prostaglandine en combinaison avec les traitements habituels, par exemple les corticostéroïdes, pourrait être envisagée.

No description available.