Human cytomegalovirus (HCMV) is a betaherpesvirus that infects up to 80% of the population worldwide, and establishes latency in monocytes and bone marrow cells. Reactivated HCMV can become an opportunistic pathogen in individuals who are immunocompromised, such as those with acquired immunodeficiency syndrome (AIDS). HCMV infection of AIDS patients causes a sight-threatening retinitis that leads to vision loss and blindness in up to 46% of this population without antiretroviral treatment. Because untreated HIV-infected individuals exhibit the loss of cell-mediated immunity and alterations in CD4+ T-helper (Th) cell cytokines, including elevation of interleukin-4 (IL-4), IL-10, and IL-17, we sought to test the hypothesis that these cytokines play key roles in governing the susceptibility to AIDS-related HCMV retinitis. This hypothesis was tested utilizing a clinically relevant mouse model of experimental murine cytomegalovirus (MCMV) retinitis that occurs in C57BL/6 mice immunosuppressed by mouse retroviruses (MAIDS). Studies revealed that MAIDS progression was associated with increased levels of IL-4 and IL-10, cytokines whose production has been associated with diminished CD8+ T-cell-mediated immunity during HIV infection. However, MCMV–infected eyes of retinitis-susceptible IL-4-/- or IL-10-/- MAIDS mice exhibited frequency and severity of retinitis and viral titers equivalent to MCMV-infected eyes of wild-type MAIDS animals. These studies indicated that neither IL-4 nor IL-10 alone play key roles in increased susceptibility to MCMV retinitis. In comparison, IL-17, an inflammatory cytokine associated with the ocular autoimmune disease uveitis, was systemically increased during the progression of MAIDS, but MCMV-infected eyes of retinitis-susceptible MAIDS mice exhibited a significant reduction in IL-17. These findings suggested that IL-17 plays no direct role in the pathogenesis of experimental MCMV retinitis. However, these results also suggested the remarkable possibility that MCMV downregulates IL-17 production, a hypothesis supported by the observation that systemic MCMV infection of healthy and MAIDS mice resulted in the downregulation of IL-17. Mechanistic studies revealed that knockdown of IL-10 resulted in a partial recovery IL-17 levels during MCMV infection. We conclude that MCMV-induced IL-17 downregulation occurs via the stimulation of IL-10 and the suppressor of cytokine signaling (SOCS)-3. Taken together, our results add new information to the immunobiology of HCMV and to our basic understanding of the pathogenesis of AIDS-related HCMV retinitis.

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2009. / Härtill 5 uppsatser.

Orientador: Lício Augusto Velloso / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-27T15:03:00Z (GMT). No. of bitstreams: 1 Silva_CarinaSolon_D.pdf: 1769268 bytes, checksum: b8a449a504bd2aa54bb737ba42860093 (MD5) Previous issue date: 2015 / Resumo: / Resumo: A interleucina-17 (IL17) está envolvida na resposta imune contra agentes patogénicos intestinais, e a sua expressão anómala no intestino pode ocorrer em condições tais como diabetes do tipo 1 (DM1), encefalomielite auto-imune e doença de Crohn. Fatores dietéticos podem alterar a microbiota intestinal desencadeando doenças metabólicas. Nossa hipótese é de que IL17 poderia ser diretamente modulada por nutrientes e pode desempenhar um papel na obesidade e diabetes tipo 2 (DM2). Aqui, nós demonstramos que as gorduras da dieta induzem a expressão IL17, predominantemente no íleo. In vivo, ilhotas pancreáticas isoladas estimuladas com IL17 apresentaram um aumento na secreção de insulina quando comparado a ilhotas não estimuladas, enquanto que a sua inibição sistémica resultou em intolerância à glicose. Animais knockout para o receptor de IL17 (IL17RA) eram intolerantes à glucose devido ao desenvolvimento embrionário anómalo das ilhotas pancreáticos, que eram menores e foram depletados de células produtoras de insulina. Nos seres humanos, os níveis circulantes de IL17 aumentaram após uma refeição. Este aumento foi significativamente maior nos indivíduos obesos normoglicêmicos do que em indivíduos obesos com diabetes. Semelhantes aos roedores, as ilhotas humanos também foram estimulados a secretarem insulina na presença de IL17. Assim nós identificamos a IL17 como um sensor intestinal de gorduras alimentares, que exerceram um efeito semelhante a hormônios incretínicos. Além disso, a presença IL17RA é importante para o desenvolvimento normal das ilhotas pancreáticas. / Abstract: / Abstract: Interleukin-17 (IL17) is involved in the immune response against intestinal pathogens, and its anomalous expression in the gut can occur in conditions such as type 1 diabetes (T1D) 1, autoimmune encephalomyelitis 2 and Crohn¿sdisease 3. Because dietary factors can change the gut microbiota, impacting metabolic diseases 4, we hypothesized that IL17 could be directly modulated by nutrients and might play a role in obesity and type 2 diabetes (T2D). Here, we show that dietary fats induced IL17 expression, predominantly in the ileum. Both in vivo and in isolated pancreatic islets, IL17 stimulated insulin secretion, while its systemic inhibition resulted in glucose intolerance. Mice KO for the main IL17 receptor (IL17RA) were glucose intolerant due to anomalous embryonic development of the pancreatic islets, which were smaller and were depleted of insulin-producing cells. In humans, blood IL17 increased following a meal. This increase was significantly higher in obese normoglycemic individuals than in obese subjects with diabetes. Similar to those of rodents, human islets were also stimulated to secrete insulin in the presence of IL17. Thus, we identified IL17 as a gut sensor of dietary fats, which exerted an incretin-like effect. In addition, the presence IL17RA was important for normal development of the pancreatic islets / Doutorado / Fisiopatologia Médica / Doutora em Ciências

Diabetes mellitus Typ 1 ist eine chronische Autoimmunerkrankung, die über eine Zerstörung pankreatischer Beta-Zellen der Langerhans-Inseln zu einem absoluten Insulinmangel führt. Ursächlich für die Zerstörung des Pankreasgewebes sind autoreaktive T-Zellen, die eine Entzündungsreaktion (Insulitis) im Pankreas bewirken. Zentrales Thema der Promotionsarbeit ist die Erforschung grundlegender quantitativer und qualitativer Eigenschaften von T-Zellen von Diabetikern im Vergleich zu gesunden, alters-gleichen Kontrollpersonen. Der Fokus der Arbeit liegt dabei auf der Analyse von naiven T-Zellen und ihrer Polarisierbarkeit in proinflammatorische Th17 (Interleukin-17-produzierende) Zellen und regulatorische T-Zellen (Tregs), die die Inflammation unterdrücken können. Voruntersuchungen der Arbeitsgruppe zeigten tendenziell eine proportionale Vermehrung von proinflammatorischen T-Zellen (Th17 Zellen) im peripheren Blut von Typ1 Diabetikern. Aus dem Vollblut wurden mittels Ficoll-Dichtezentrifugation periphere mononukleäre Zellen des Blutes (PBMC) gewonnen. Über magnetisch aktivierte Zell-Separation (MACS) wurden naive T-Zellen (CD4+CD45RA+CD27+) aus den PBMCs isoliert. Diese naiven Zellen wurden angeregt sich zu adulten, immunkompetenten Zellen zu differenzieren. Die Antigenstimulation der T-Zellen wurde imitiert durch Aktivierung mit Antikörpern gegen die Moleküle CD3 und CD28 oder einem C. albicans-Antigen. Die Stimulation wurde unter Co-Kultivierung mit autologen antigenpräsentierenden Zellen durchgeführt. Die Richtung der Differenzierung wurde durch Zugabe verschiedener Zytokin-Cocktails beeinflusst. Nach Abschluss der Kultivierung wurde sowohl der Phänotyp der Zellen als auch deren Fähigkeit bestimmte Zytokine zu produzieren mittels Durchflusszytometrie (FACS) bestimmt. Weiterhin wurden Suppressionsassays durchgeführt, bei denen die Suppressionsfähigkeit von aus naiven T-Zellen induzierten Tregs auf autologe PBMCs von Typ 1 Diabetes Patienten überprüft wurde. In dem zunächst durchgeführten Vergleich von Kindern mit einer Erstmanifestation mit gesunden Kontrollen konnte eine stärkere IFN-Produktion gezeigt werden mit signifikanten Unterschieden innerhalb der Ki67+ Zellen. Interessanterweise zeigte sich diese stärkere IFN Sekretion der T-Zellen der Diabetiker unter Bedingungen, die die Expression von TH17-Zellen fördern sollten. Zusätzlich konnten T-Zellen nachgewiesen werden, die für IFN und IL17 doppelt positiv waren. In weiteren Versuchen wurden auch Vergleiche zwischen längere Zeit an Diabetes erkrankten Kindern und erwachsenen Diabetikern mit gesunden Kontrollen durchgeführt. Bei den erwachsenen Diabetikern konnten dabei mehr IFN+/IL17+ T Zellen innerhalb der Ki67+ T-Zellen nachgewiesen werden als bei den Kontrollen. Die Zellkulturexperimente wurden im Weiteren mit C. albicans-Antigen als einem spezifischen Stimulus des Immunsystems durchgeführt. Die Untersuchung zeigte zunächst einmal, dass das C. albicans-Antigen bezüglich Proliferation und T-Zell-Differenzierung ein deutlich schwächerer Stimulus im Vergleich zur Stimulation mit aCD3/aCD28 war. Beobachtet werden konnte allerdings, dass es durch Stimulation mit dem C. albicans-Antigen insgesamt zu einer stärkeren Aktivierung des TH17-Zell-Systems kam mit Ausnahme der längere Zeit an einem Diabetes erkrankten Kinder, die eine geringere IL17-Produktion im Vergleich zu den Kontrollen aufwiesen. Insgesamt zeigten sich teils deutliche Unterschiede zwischen den Gruppen der Diabetiker, so dass von einer Beeinflussung der Ergebnisse durch Krankheitsdauer, Krankheitsaktivität, Alter der Probanden und Therapiedauer ausgegangen werden muss. Die Untersuchung des Proliferationsverhaltens ergab sowohl bei den proinflammatorischen T-Zellen als auch bei den Tregs keine Unterschiede zwischen den Diabetikern und den Kontrollpatienten, ebenso wie die quantitative Untersuchung der Ausbildung von CD25+FOXP3+ Tregs aus den naiven T-Zellen unter unspezifischer Stimulation. Unter spezifischer Stimulation hingegen zeigten sich mehr Tregs bei den Kindern mit einer Erstmanifestation und den erwachsenen Diabetikern. Ebenfalls unter Stimulation mit dem C. albicans-Antigen zeigten sich unter proinflammatorischen Bedingungen bei den Kindern mit einer Erstmanifestation und unter antiinflammatorischen Bedingungen bei den erwachsenen Diabetikern ein signifikant höherer Anteil CD127- Tregs (CD25+FOXP3+) im Vergleich zu den Kontrollprobanden. Interessanterweise zeigte sich bei den erwachsenen Diabetikern sowohl bei spezifischer als auch bei unspezifischer Stimulation eine stärkere Produktion von IL17 durch die Tregs. Die Untersuchung der Expression des Homing-Rezeptors CD62L auf den Tregs ergab keine signifikanten Unterschiede, aber eine höhere Expression bei allen Diabetikern im Vergleich zu den jeweiligen Kontrollgruppen und die Untersuchung des IFN-Rezeptors erbrachte keine signifikanten Unterschiede zwischen den Gruppen, allerdings zeigten sich die Mediane und Mittelwerte bei den Kindern mit einer Erstmanifestation im Vergleich zu den Kontrollen bei unspezifischer Stimulation erhöht. Zur Ergänzung der Zellkulturexperimente wurden im Weiteren Suppressionsversuche mit aus naiven T-Zellen induzierten Tregs durchgeführt. Die Suppressionsversuche konnten eine geringere Hemmung der Proliferation durch die induzierten Tregs der Diabetiker zeigen und damit auf eine mögliche Dysfunktion der Tregs deuten. Um Möglichkeiten der Beeinflussung des Immunsystems zu untersuchen wurden die Zellkulturen erneut unter Blockade von IFNy und Zugabe von TGFb durchgeführt. Die Blockade von IFNy führte zu einer geringer ausgeprägten Differenzierung und Proliferation der T-Zellen. Weiterhin konnten in der intrazellulären Färbung weniger IFN positive T-Zellen gefunden werden und es zeigte sich eine stärkere Expression des IFN-Rezeptors. Bei den Kindern mit einer Erstmanifestation zeigte sich zusätzlich auch eine geringere Ausprägung der IL17+ T-Zellen. Hier ergaben sich keine Unterschiede in der Quantität der Tregs. Die erwachsenen Diabetiker zeigten hier weniger Tregs, dafür aber eine stärkere Proliferation innerhalb der Tregs. Bei den Kindern mit einem längere Zeit bestehenden Diabetes hingegen zeigten sich keine quantitativen Unterschiede. Die Beeinflussung durch Zugabe von TGFb bei den erwachsenen Diabetikern und den Kindern mit einer Erstmanifestation führte zu einer geringeren T-Zell Differenzierung mit mehr naiven T-Zellen und weniger Memory-T-Zellen sowie zu einer geringeren IFNy Expression. Bei den Erwachsenen zeigte sich ebenso eine geringere Proliferation, geringe Anzahlen für Tregs sowie eine geringe Ausprägung der Expression von CD62L und der Produktion von IL17 durch Tregs. Insgesamt konnte gezeigt werden, dass es Unterschiede zwischen den proinflammatorischen T-Zellen sowie den induzierten Tregs der Diabetiker im Vergleich zu den gesunden Kontrollen gibt. Insbesondere die Bedeutung von IFNy bei den Erstmanifestation konnte gezeigt werden. Aber auch die Sekretion von IL17 oder die Expression von CD62L auf den Tregs stellen interessante Ansatzpunkte zur weiteren Erforschung des Diabetes dar. Weiterhin zeigten die Suppressionsversuche eine gestörte Regulation durch die induzierten Tregs bei den Diabetikern. Sowohl die Blockade von IFNy als auch die Zugabe von TGFb zeigten inflammationshemmende Wirkung bei den Lymphozyten der Diabetiker in vitro und stellen interessante Ansatzpunkt für eine mögliche Therapie dar. / Type 1 diabetes mellitus is a chronic autoimmune disease which causes a destruction of pancreatic beta cells and results in an absolute lack of insulin. Autoreactive T-cells cause an inflammation in the pancreas (insulitis) and are responsible for the destruction of the beta cells. Main topic of this thesis is the investigation of fundamental quantitatively and qualitatively features of T-cells in humans with type 1 diabetes mellitus in comparison to healthy, age-matched controls. The main point of view is directed on the analysis of naive T-cells and their ability to polarize in proinflammatory TH17-cells (Interleukin 17 producing T-cells) and regulatory T-cells (Tregs) which are able to suppress an inflammatory reaction. Earlier studies in our work group suggested a proportional increase of proinflammatory T-cells in the peripheral blood of patients with type 1 diabetes mellitus. A density centrifugation with Ficoll was performed to isolate peripheral blood mononuclear cells (PBMC). Magnetic activated cell sorting (MACS) was used to extract naive T-cells (CD4+CD45RA+CD27+) out of the PBMC-group. These isolated naive T-cells were stimulated to differentiate into mature, immunocompetent T-cells. The stimulation was imitated by T-cell activation with antibodies against CD3 and CD28 or with a C. albicans-antigen. The activated T-cells were co-cultured with autologous, antigen presenting cells (APC). The direction of differentiation was influenced by supplementation of various cytokine-cocktails. After finishing the cultivation, the phenotype of the T-cells as well as their ability to produce distinct cytokines was determined by fluorescent activated cell sorting (FACS). Furthermore, suppression assays were performed in which the ability of (out of naive T-cells induced) Tregs to suppress autologous PBMC of humans with type 1 diabetes mellitus was investigated. First there was a comparison between children with a new-onset of type 1 diabetes mellitus (T1DM) and healthy controls. This investigation showed a stronger production of interferon gamma (IFN) with significant differences in the Ki67 positive subgroup in T1DM children. Interestingly this was found under culture conditions which should promote the expression of an TH17-phenotype. Additionally, T-cells were discovered which were double positive for IFN and IL17. In further experiments the T-cells of children and adults with a long-standing diabetes mellitus were compared to healthy donors. In the adult group it was possible to show more IFN/IL17 positive T-cells in the Ki67 positive subgroup in comparison to the controls. For further experiments an C. albicans-antigen was used as a T-cell activator. Primarily it was obvious that the C. albicans-antigen was a much weaker stimulus concerning proliferation and T-cell differentiation. But overall there was a stronger activation of the TH17-cell system except for the children with long-standing diabetes mellitus who had a lower amount of IL17 in comparison to the healthy controls. All together there were clear differences between the different groups of humans with type 1 diabetes mellitus so that the results are probably influenced by activity und duration of disease as well as patients age and duration of therapy. The research concerning the proliferation as well as the quantity of CD25+FOXP3+ Tregs showed neither differences for the proinflammatory Tcells nor the Tregs under unspecific stimulation. When specific stimulation was performed, the children with a new-onset of diabetes mellitus and the adults with diabetes mellitus showed an increased number of Tregs. Additionally, under stimulation with C. albicans under proinflammatory culture conditions there was a higher proportion of CD127 negative Tregs (CD25+FOXP3+CD127-) in the children with a new-onset diabetes and the adult diabetics in comparison to the healthy controls. Surprisingly there was a stronger IL17-production among the Tregs in the adult diabetics under specific as well as under unspecific stimulation. Although investigations on expression of the homing receptor CD62L on the surface of Tregs yield no significant differences, there was a non significant higher expression in every diabetic group in comparison to the controls. Similar the expression of the IFN-receptor shows no significant differences but the consideration of the values for median and average showed higher values in the children with newly onset diabetes than in the healthy controls under unspecific stimulation. Furthermore, suppression assays were performed with induced Tregs which were induced out of naive T-cells. In this investigation a weaker ability to inhibit the proliferation of T-cells by the induced Tregs of the diabetics were found. This is a possible hint for a dysfunction of Tregs in humans with type 1 diabetes mellitus. To investigate possibilities for influencing the immune system the earlier performed cell cultures were repeated now with blocking IFN or supplement TGFb. The blocking of IFNy leads to a weaker differentiation and proliferation of Tcells. Furthermore, the intracellular staining showed decreased numbers of IFNy positive T-cells but a higher expression rate of the IFNy-receptor. The children with a new-onset of diabetes mellitus showed additionally lower values for IL17 positive T-cells but therefore a greater proliferation rate among the Tregs. On the other hand there were no quantitative differences noted in the children with long-standing diabetes. Supplementation of TGFb leads to a weaker T-cell differentiation with greater numbers of naive T-cells und lower numbers of memory T-cells as well as a lower IFNy-expression rate in the T-cells of the children with a new-onset diabetes and the adult diabetics. The adult diabetics showed furthermore a weaker T-cell proliferation, decreased Treg numbers and a lower expression of CD62L as well as a lower production of IL17 by Tregs. All together it was possible to show differences between the proinflammatory T-cells and the induced Tregs of humans with diabetes mellitus in comparison to healthy controls. Especially the meaning of IFNy for the disease in children with new-onset diabetes mellitus was shown. Furthermore, the secretion of IL17 or the expression of CD62L on Tregs are interesting starting points for further investigations. Additionally, it was possible to show that the ability to inhibit the proliferation of inflammatory T-cells by the induced Tregs of the diabetics is disturbed. The blocking of IFNy as well as the supplementation of TGFb showed inflammation inhibiting effects in the T-cells of the diabetics in vitro and is an interesting starting point as a potential future therapy.

No description available.

Antibodies, as forerunners in the field of biological drugs, are originally an organism’s answer to the invasion of different pathogens. Today, antibodies are a common treatment for many chronic diseases such as the immune-mediated inflammatory diseases rheumatoid arthritis or psoriasis. It is suspected that the cytokines interleukin 17a (IL17a) and interleukin 17c (IL17c) are involved in those diseases and are commonly treated with antibodies that inhibit the cytokines. Even though antibodies have been a huge success as biological drugs they also have downsides when it comes to their production, size and stability. In quest of finding alternatives to antibodies in diagnostics and therapy, a novel class of biologics has been developed. So-called alternative scaffold proteins are small polypeptide chains that can be engineered to show affinity towards different biomarkers. ABD-Derived Affinity ProTeins or ADAPTs are one example of these alternative scaffolds that can be modified to bind a biomarker as target and keep their affinity to Human Serum Albumin (HSA) at the same time, making them bispecific. In this project, twenty-four previously selected ADAPT binder candidates that have shown good prospects towards IL17a and IL17c in previous experiments were cloned, produced, purified and characterized to determine if they show potential as tools in diagnostics or therapy of autoimmune diseases. The proteins were produced in E. coli, purified by affinity chromatography and characterized using Surface Plasmon Resonance (SPR), Circular Dichroism (CD) and Size Exclusion Chromatography (SEC). All candidates were successfully cloned into E. coli and out of these, 10 could be produced and 5 showed affinity towards their target using SPR. Examination by SEC and CD showed that the protein variants did not seem to be structurally stable and hints of impurities in the samples could be detected. This and a low yield could be further confirmed via SDS-PAGE. In conclusion, binders were produced that could theoretically be promising candidates as tools in diagnostics or therapy of chronic diseases were IL17a and/or IL17c are important. Nevertheless, in order to support these claims further investigations and developments are necessary. / Antikroppar, som föregångare inom området biologiska läkemedel, är ursprungligen en organisms svar på invasionen av olika patogen. Idag är antikroppar en vanlig behandling för många kroniska sjukdomar, såsom de immunmedierade inflammatoriska sjukdomarna reumatoid artrit eller psoriasis. Cytokinerna interleukin 17a (IL17a) och interleukin 17c (IL17c) tros vara involverade i dessa sjukdomar och behandlas vanligtvis med antikroppar som hämmar cytokinerna. Trots att antikroppar har varit en stor framgång som biologiska läkemedel har de också nackdelar när det gäller deras produktion, storlek och stabilitet. För att hitta alternativ till antikroppar inom diagnostik och terapi har en ny klass av biologiska läkemedel utvecklats. Så kallade alternative scaffold proteins är små polypeptidkedjor som kan manipuleras för att visa affinitet gentemot olika biomarkörer. ABD-Derived Affinity ProTeins eller ADAPTs är ett exempel på dessa alternative scaffolds som kan modifieras för att binda en biomarkör som mål utan att påverka affiniteten till Humant Serum Albumin (HSA), vilket gör dem bispecifika. I detta projekt klonades, producerades, renades och karakteriserades tjugofyra tidigare utvalda ADAPT-bindarkandidater som har visat goda förutsättningar gentemot IL17a och IL17c i tidigare experiment. Proteinerna producerades i E. coli, renades genom affinitetskromatografi och karakteriserades med användning av Surface Plasmon Resonance (SPR), Circular Dichroism (CD) och Size Exclusion Chromatography (SEC). Alla kandidater klonades framgångsrikt i E. coli och av dessa kunde 10 produceras. Fem bindare visade affinitet till deras mål med SPR. Undersökning med SEC och CD visade dock att proteinvarianterna inte var strukturellt stabila och antydan till föroreningar kunde detekteras i proverna. Detta och ett lågt utbyte kunde ytterligare bekräftas via SDS-PAGE. Sammanfattningsvis kunde bindare producerades och dessa kan teoretiskt vara lovande kandidater till diagnostik eller terapi av kroniska sjukdomar där IL17a och/eller IL17c är viktiga. För att stödja dessa påståenden krävs dock ytterligare experiment och utveckling av bindarna.

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In der nicht vollständig geklärten Pathogenese der juvenilen idiopathischen Arthritis (JIA) spielen insbesondere Effektor-T-Zellen und regulatorische T-Zellen (Tregs), sowie das Kontinuum ihrer plastischen Zelltypen eine wichtige Rolle. Im arthritischen Milieu, das auch Interleukin-17 (IL-17) beinhaltet, verschiebt sich das Gleichgewicht dieser Zellen hin zur Inflammation. Ziel dieser Arbeit war es, die T-Zellbalance im peripheren Blut von JIA-Patienten mit gesunden Kontrollen (HC) zu vergleichen, sowie den Einfluss von IL-17, anti-IL-17 und eines Th17-stimulierenden, proinflammatorischen Zytokinmilieus auf Phänotyp und Funktion der Tregs zu untersuchen. Es erfolgte die durchflusszytometrische Analyse des Lymphozytenpools von 16 JIA- und 10 HC-Probanden. Isolierte CD25+CD127-CD4+ Tregs wurden mit den genannten Stimuli kultiviert und danach durchflusszytometrisch phänotypisch sowie in Co-Kultur mit peripheren mononukleären Zellen (PBMCs) auf ihre Suppressionsfunktion untersucht. Wir stellten erhöhte Proportionen von Th17-Zellen, Tregs und effector-like Tregs in JIA-Patienten fest. Bei Stimulation mit dem Th17-Cocktail zeigte sich eine verminderte Suppression der Effektor-Zellen durch Tregs bei zeitgleich vermehrter FoxP3-Expression insbesondere in JIA-Tregs. Secukinumab bewirkte eine Anpassung der FoxP3-Expression der Tregs in der Patientengruppe auf etwa das Niveau der gesunden Kontrollen. Insgesamt bestätigt diese Arbeit eine proinflammatorische Dysbalance bei JIA-Patienten mit Shift zu Th17-like Tregs als möglicherweise pathologischen Phänotyp. Ursache für die verminderte Suppression ist vermutlich eine gesteigerte Resistenz der Effektor-Zellen durch das Inflammationsmilieu. Die vermehrte FoxP3-Expression der JIA-Tregs ist am ehesten durch eine gesteigerte Zellaktivierung zu erklären. Diese erhöhte Sensitivität der Tregs für inflammatorische Stimuli mit vermehrter Aktivierung ist ein möglicher Ansatzpunkt für zukünftige Therapien. Die Adjustierung der FoxP3-Expression unter Secukinumab in der JIA-Gruppe auf Niveau der Kontrollen bildet daher einen denkbaren zusätzlichen therapeutischen Effekt der IL-17A Blockade durch potenzielle intrinsische Stabilisierung des Phänotyps der Tregs bei der JIA ab. / Background and Objective: As the exact pathophysiology of juvenile idiopathic arthritis (JIA) is yet not fully resolved, an important focus of research lays nowadays in the delicate balance between regulatory T cells (Tregs) and effector T-cells. In an arthritic milieu, involving interleukin-17 (IL-17), plasticity towards proinflammatory cell types is seen. The aim of the study was to analyze the distribution of Tregs and effector T-cells in the peripheral blood of JIA patients and healthy controls (HC). Besides that, the influence of IL-17, of anti-IL-17 and of a Th17-stimulating environment on phenotype and function of Tregs was investigated to determine a possible drift away from or towards an antiinflammatory immune status. Methods: Peripheral blood mononuclear cells (PBMCs) were obtained from blood samples of 16 JIA patients and 10 HC and compared for differences in the lymphocytes’ characteristics. Isolated CD25+CD127-CD4+ Tregs were analyzed with flow cytometry after cultivation with the above-mentioned stimulating agents. Furthermore, suppression assays were performed to assess the Treg-mediated inhibition on proliferation of autologous PBMC proliferation after co-culture. Results: A shift towards pro-inflammatory T cells with elevated Th17-levels and concomitant increased amount of Tregs and Th17-like Tregs in JIA patients was detected. A diminished suppression of PBMC proliferation by Tregs in the Th17-stimulation environment was determined. This environment also promoted an increased FoxP3-expression on Tregs, especially in JIA. Secukinumab lead to adjustment of FoxP3-expression in JIA-Tregs to levels found in HC. Conclusion: Our results implicate that the increased proportions of Th17 cells and Th17-like Tregs might play an important part in the pathophysiology of JIA mediating the proinflammatory dysbalance. The mitigated inhibition of PBMC-proliferation in the Th17-environment is most likely the result of an effector cell resistance. The augmented FoxP3-expression in Th17-environment may be due to an increased cell activation, which especially JIA Tregs were prone to. This increased sensitivity of Tregs to inflammation might open new therapeutic approaches. The difference of FoxP3-activation was less pronounced after cultivation with Secukinumab, suggesting an adjustment of Treg activation in JIA to levels found in HC. This could demonstrate an additional benefit in IL-17A-inhibition in JIA possibly via intrinsically stabilizing the Treg phenotype.

Endothelial cell (EC) activation is a change of the endothelium from a quiescent state to one that is involved in immune reactions. Activation of ECs is associated with the inception of atherosclerosis. Atherosclerosis is a chronic inflammatory disease that involves adaptive and innate immunity. There are many pro-inflammatory stimuli which activate the endothelium. The pro-inflammatory cytokine interleukin-17 (IL-17) has been shown to activate lung microvascular ECs. Enhanced expression of the IL-17 receptor by synovial ECs is associated with rheumatoid arthritis. These studies suggest that IL-17 plays an important role in EC biology. Nevertheless, the role of IL-17 in EC activation and endothelial dysfunction in the context of hyperlipidemia-induced atherosclerosis has not been studied. In the current study, we investigated the role of IL-17 in EC activation in vitro with mouse aortic ECs and human aortic ECs. In addition, we used the IL-17/ApoE double knock-out mouse to determine the role of IL-17 in vessel function and atherosclerosis development. First, we found that hyperlipidemia increased the number of IL-17-producing cells in the spleens from wild type mice and ApoE-/- mice that were fed a Western diet when compared to their respective normal chow diet controls. We also found that after treatment with the pro-atherogenic factor, oxidized LDL, there was an increase in the expression of IL-17 receptor by ECs. Using an EC specific array, we found that IL-17 induced significant up-regulation of four genes that are associated with EC activation in mouse aortic ECs. The four genes induced in IL-17-treated mouse aortic ECs were Cxcl1, Cxcl2, Il6, and Csf2. Moreover, we also found that IL-17 induced these four genes in human aortic ECs, and we showed that enhanced monocyte adhesion to ECs was dependent on these four genes. It was previously observed that a Western diet induced vessel dysfunction in the aortas of ApoE-/- mice. Thus, we sought to determine whether IL-17-deficiency rescues impaired endothelium-dependent relaxation in ApoE-/- mice that were fed a Western diet with the Wire Myograph System. We found that ApoE-/- mice on a 3-week Western diet had impaired endothelium-dependent relaxation when compared to IL-17-/-ApoE-/- mice. Endothelium-independent relaxation in response to sodium nitroprusside (SNP) and contraction responses induced by potassium chloride (KCl) and phenylephrine (PE) were not different in ApoE-/- mice and IL-17-/-ApoE-/- mice. Since our in vitro studies and vessel function assay pointed to a pro-atherogenic role for IL-17, we investigated lesion formation in ApoE-/- mice and IL-17-/-ApoE-/- mice. Lesion formation was assessed with Sudan IV staining of the whole aorta and Oil red O staining of aortic sinus cross sections. IL-17 deficiency in ApoE-/- mice did not affect atherosclerotic lesion formation in our study. Hyperlipidemia is a well-established risk factor for atherosclerosis so we investigated whether the pro-atherogenic role of IL-17 may have been compromised by lipid levels in vivo. The lipid profiles of mice which measured the levels of LDL, HDL, triglyceride, non-esterified free fatty acid, and total cholesterol were determined. The lipid profiles showed that IL-17 deficiency in ApoE-/- mice modulated the levels of the lipids in the plasma. Taken together, our data suggest that IL-17 is up-regulated in hyperlipidemia and IL-17 induces aortic EC activation. IL-17 also contributes to endothelial dysfunction in ApoE-/- mice induced by a Western diet. Moreover, IL-17 may modify lipid metabolism in mice. The effects of IL-17 on lipid levels may weaken its pro-atherogenic potential and contribute to the lack of an atherosclerotic phenotype in our atherosclerosis study. Our current work has shed light on the role of IL-17 on EC biology and has provided insights into the effects of IL-17 on EC activation, lipid modification, and vascular function. These important findings may serve as the stepping stone to the development of therapeutics that target vascular inflammation and its underlying mechanisms. The studies in this dissertation were supported by grants from the National Institutes of Health (NIH) and a fellowship from the American Heart Association (AHA). / Pharmacology