Introdução: a proteína mitocondrial codificada pelo gene Nicotinamide Nucleotide Transidrogenase (NNT) regula o processo intramitocondrial de desintoxicação de espécies reativas de oxigênio (EROs). Defeitos na homeostase desse sistema (sistema Redox) podem comprometer a esteroidogênese adrenal. Objetivo: caracterizar o impacto funcional da nova variante missense NNT p.G866D (c.2597G>A) e sua associação com o fenótipo de deficiência familiar de glicocorticoide (DFG). Indivíduos e Métodos: Caso índice: lactente com DFG diagnosticada aos 18 meses, seus pais e irmão assintomáticos e controles saudáveis. O ácido desoxirribonucleico (DNA) genômico do caso índice foi submetido a sequenciamento exômico que revelou, entre algumas variantes gênicas-candidatas, a variante (c.2597G> A; p.G866D) em homozigose no exon 17 do gene NNT. Avaliou-se a segregação familiar dessa variante com o fenótipo de DFG. A análise funcional in vitro dessa variante foi realizada em cultura transitória de células mononucleares sanguíneas do paciente, heterozigotos e controles em condição basal e após a indução do estresse oxidativo com 100?m de H2O2 por cinco horas. A expressão do RNAm do gene NNT nessas células foi realizada por meio de qPCR. Os parâmetros mitocondriais avaliados foram: a produção intracelular de espécies reativas de oxigênio (EROS) detectadas por CMDCFDA, a concentração de glutationa reduzida (GSH) e ATP celular medidos ensaios luminescentes, , além da massa e potencial de membrana mitocondrial avaliados com o probe MitoTracker. Resultados: A análise de segregação familiar confirmou a segregação desta variante em homozigose com o fenótipo de DFG. A expressão do NNT RNAm foi semelhante entre paciente, heterozigotos e controles. Em homozigose a variante p.G866D no gene NNT causa aumento na produção de EROs, diminuição de GSH e diminuição da massa e potencial de membrana mitocondrial, tanto em condições basais, quanto após a indução de estresse oxidativo. Após a indução de estresse oxidativo as concentrações de ATP foram menores no homozigoto NNT p.G866D do que nos controles. Conclusão: este estudo confirma a associação da variante NNT em homozigose com o fenótipo de DFG Tipo quatro. In vitro o mutante homozigoto NNT p.G866D reduz significativamente os mecanismos de defesas antioxidantes, comprometendo o sistema da glutationa redutase, levando ao acúmulo de EROs. / Background: mitochondrial Nicotinamide Nucleotide Transidrogenase (NNT) is essential in the intracellular reactive oxygen species (ROS) detox process. Defects in this system may impair adrenal steroidogenesis by yet not fully understood mechanism. Aim: we sought to characterize the functional impact of the new NNT p.G866D (c.2597G>A) variant and its association with familial glucocorticoid deficiency (FGD). Subjects and Methods: evaluated subjects included the index case diagnosed with FGD at the age of 18 months, his asymptomatic parents and young brother and healthy controls. The Index case genomic DNA was evaluated by whole exome sequencing, which revealed several potential candidate variants, including the homozygous NNT p.G866D. We then analyzed the family pedigree to confirm the segregation of this variant with FDG phenotype. To prove the genotype-phenotype association, this new variant was comprehensive evaluated in vitro. Transient mononuclear cell cultures from the patient, family members and controls were performed both in basal conditions and after oxidative stress induced by 5-hours treatment with 100?m de H2O2. We analyzed NNT RNAm expression by qPCR and mitochondrial parameters including ROS intracellular production by 20, 70-diacetate dichlorodihydrofluorescein, reduced glutathione (GSH) and cellular ATP levels by luminescence, and mitochondrial mass and mitochondrial membrane potential by Mitotraker Probe system. Results: family pedigree analysis confirmed the segregation of the homozygous NNT p.G866D variant with FGD. In vitro, no differences in RNAm expression was found among patients, heterozygous carriers and healthy controls. Both in basal and under stress conditions, the homozygous p.G866D NNT variant exhibited significantly increased ROS production, decreased GSH levels and decreased mitochondrial parameters. In addition, under H2O2 oxidative stress, the homozygous p.G866D NNT also leaded in decreased ATP intracellular . Conclusion: this study clearly confirms the association of the homozygous NNT p.G866D variant with the phenotype of FGD. In vitro, this variant significantly impairs anti-oxidants mechanisms and affects the glutathione reductase systems resulting in increased ROS accumulation.

Dans le système nerveux central (SNC), l'hippocampe est une structure majeure pour les fonctions cognitives et comportementales. Le Brain-Derived Neurotrophic Factor (BDNF), un acteur clé dans ces fonctions neuronales, est fortement exprimé dans l'hippocampe. La structure du gène Bdnf murin est complexe, comportant 8 exons non codants (I à VIII), chacun avec un promoteur spécifique (1 à 8) et un exon IX codant commun. Les glucocorticoïdes (GC) exercent des actions pleiotropes sur ces processus neuronaux en se liant et en activant le récepteur des glucocorticoïdes (GR), et le récepteur des minéralocorticoïdes (MR). Le GR est un facteur de transcription, modulant la transcription de ses gènes cibles, en se liant directement aux éléments de réponse des glucocorticoïdes ou en interagissant indirectement sur d’autres facteurs de transcription. Il a été suggéré que l'expression de Bdnf est régulée par le stress et les concentrations élevées de GC. Cependant, il reste à définir si BDNF est un gène cible du GR et quels sont les mécanismes moléculaires impliqués. Dans ce travail, nous avons démontré que les fortes concentrations de GC diminuent l'expression de l'ARNm de Bdnf via le GR dans divers modèles cellulaires neuronaux. Dans des cultures primaires de neurones hippocampiques de souris et dans les cellules BZ, les transcrits de BDNF contenant l’exon IV et VI sont reprimés par le GR. Par ailleurs les transfections transitoires démontrent que l’activité du promoteur 4 est diminuée par GR. Les expériences de mutagenèse et de ChIP ont révélé que la répression induite par le GR sur l'expression et l’activité transcriptionnelle de Bdnf implique un petit fragment de 74 bp situé dans le promoteur en amont de l'exon IV. La localisation précise de l’interaction génomique du GR et les facteurs de transcription potentiels mis en jeu restent à identifier. Ce travail a contribué à une meilleure compréhension des mécanismes impliqués dans la régulation de l’expression de Bdnf par GR. Il apporte de nouveaux éléments sur les interactions moléculaires et fonctionnelles entre la signalisation GC et celle de BDNF dans les neurones, d’importance majeure dans la physiopathologie du SNC. / In the central nervous system (CNS), the hippocampus is a structure of major importance for cognitive and behavioral functions. The brain-derived neurotrophic factor (BDNF), a key player in such neuronal functions is highly expressed in the hippocampus. Rodent Bdnf gene structure is relatively complex, composed of 8 noncoding exons (I to VIII), each one with a specific promoter (1 to 8), and one common coding exon IX. Glucocorticoids (GC) exert pleiotropic actions on neuronal processes by binding to and activating the glucocorticoid receptor (GR), as well as the mineralocorticoid receptor (MR). GR functions as a transcription factor, directly by interacting to glucocorticoid response elements or indirectly by interacting with other transcription factors, leading to the regulation of target gene transcription. It has been suggested that Bdnf expression is regulated by stress and high GC concentrations. However, it remains to define whether Bdnf is a GR target gene and what are the underlying molecular mechanisms. Herein, we demonstrate that high GC levels downregulate total Bdnf mRNA expression via GR in various in vitro neuron-like cellular models. In primary cultures of mouse hippocampal neurons and BZ cells, BDNF IV- and VI-containing transcripts are involved in this regulatory mechanism. Moreover, in transient transfections, promoter 4 activity was reduced by activated GR. Furthermore, ChIP analysis and mutagenesis experiments demonstrate that the GR-induced repression on Bdnf expression and transcriptional activities occurs through GR binding to a small 74 bp promoter sequence upstream of exon IV. The exact GR binding site on DNA and its putative transcription factor partners are currently under investigation. Altogether, these findings contribute to a better understanding of the mechanisms by which GR represses BDNF expression. Our study brings new insights into the molecular interactions between GC signaling and BDNF signaling in neurons, both important pathways in the pathophysiology of the CNS.

Rheumatoid arthritis (RA) is a common chronic inflammatory disease that affects about 1% of the Western population. Glucocorticoids (GC) are widely used for the treatment of RA and other immune-mediated diseases, such as asthma, but their use is associated with adverse effects on bone metabolism. Because of that, new selective GC receptor (GR) agonists (SEGRAs) with the potential for an improved risk/benefit profile have been developed. Compound A (CpdA) is a novel SEGRA, which showed an improved risk/benefit profile concerning glucose metabolism, however the effects on bone are not well investigated yet. Initial in vitro studies of our group showed bone-sparing potential of CpdA. The aim of this study was to investigate whether CpdA also possesses beneficial effects on bone in vivo. Therefore, the first step was to explore the effects of CpdA on healthy bone metabolism, followed by the analysis of the anti-inflammatory potential in a murine model of RA. To mimic the effects of continuous therapy, bone loss was induced in FVB/N mice by implanting slow-release pellets containing placebo, prednisolone (PRED; 3.5 mg), or CpdA (3.5 mg). After four weeks, mice were killed and the effects on the skeleton were examined. By performing in vitro studies with human bone marrow stromal cells (BMSC) and murine osteocyte-like cells (MLO-Y4 cells), the underlying mechanisms were assessed. Here, we focused on the RANKL/OPG ratio as a marker for the osteoclastogenic potential as well as on the Wnt signaling pathway. Whereas PRED reduced the total and trabecular bone density in the femur and in the spine, CpdA did not influence these parameters. These results were confirmed by histomorphometry as the mineral apposition rate was decreased by PRED whereas the number of osteoclasts was increased. Reduced bone formation was furthermore paralleled by a decline in the serum bone formation marker pro-collagen type 1 N-terminal peptide (P1NP) and decreased skeletal expression of osteoblast markers, as well as increased serum levels of the osteoblast inhibitor dickkopf-1 (Dkk-1). Additionally, serum CTX-1 and the RANKL/OPG ratio in the bone tissue were increased by PRED. None of these effects were observed with CpdA. Moreover, CpdA did not increase the RANKL/OPG ratio in MLO-Y4 cells and failed to transactivate Dkk-1 expression in bone tissue, BMSC, and osteocytes. To analyze the anti-inflammatory properties of CpdA, arthritis was induced in DBA/1 mice by injection of type II collagen. After disease onset, mice were treated for ten days with PBS (placebo), dexamethasone (DEX; 100 µg/mouse), or CpdA (300 µg/mouse). The latter was able to decrease disease activity, paw swelling, and paw temperature, but was less potent compared to DEX. In addition, T cells isolated from CpdA- and DEX-treated animals were less active based on proliferation rates after stimulation with type II collagen and produced smaller amounts of interferon-γ as compared to T cells from PBS-treated mice. The weaker potency of CpdA as compared to DEX in preventing infiltration of inflammatory cells, induction of osteoclastogenesis, and destruction of articular cartilage was confirmed by histological assessment of the joints. While CpdA was unable to prevent inflammation-induced bone loss, it did not aggravate bone loss or alter bone density in healthy control mice. In conclusion, this study underlines the bone-sparing potential of CpdA compared to conventional GC in a murine model of GC-induced bone loss. Even though a moderate anti-inflammatory potential of CpdA was demonstrated, it was unable to prevent inflammation-induced bone loss. Despite the bone-sparing effects of CpdA in healthy mice, its narrow therapeutic window limits its use in clinical practice. Nevertheless, this study highlights important molecular mechanisms of GC-induced bone loss showing that by avoiding increases in the RANKL/OPG ratio or Dkk-1 in osteoblast lineage cells, GC-induced bone loss may be improved. / Rund 1% der westlichen Bevölkerung leidet an rheumatoider Arthritis, einer chronischen Entzündung der Gelenke. Für deren Behandlung werden häufig Glukokortikoide (GC) eingesetzt. Trotz ihrer potenten entzündungshemmenden Wirkung ist ihr Einsatz aufgrund der negativen Auswirkungen auf den Knochenstoffwechsel eingeschränkt. Um ein besseres Risiko/Nutzen-Profil zu erzielen, wurden selektive GC-Rezeptoragonisten (SEGRAs) entwickelt, die weiterhin potent anti-inflammatorisch wirken, während negative metabolische Effekte ausbleiben. Compound A (CpdA) ist ein Vertreter dieser Gruppe, der in Mäusen ein verbessertes Behandlungsprofil hinsichtlich des Glukosestoffwechsels zeigte. Die Wirkung auf den Knochen wurde bisher nur unzureichend untersucht. Erste in vitro Ergebnisse unserer Gruppe zeigten knochenfördernde Eigenschaften von CpdA. Ziel dieser Arbeit war es zu untersuchen, ob CpdA auch in vivo ein knochenschonendes Potenzial besitzt. Dafür wurden zunächst die Effekte von CpdA auf den gesunden Knochenstoffwechsel untersucht, um anschließend seine Wirkung in einem Mausmodell der rheumatoiden Arthritis zu testen. Um die Effekte einer Dauertherapie mit CpdA nachzustellen, wurden Slow-release-Pellets mit Plazebo, Prednisolon (PRED; 3,5 mg) beziehungsweise CpdA (3,5 mg) in FVB/N-Mäuse implantiert. Nach vier Wochen wurden die Effekte der Substanzen auf den Knochen untersucht. Um mögliche zugrundeliegende Mechanismen zu eruieren, wurden humane Knochenmarkszellen und murine Osteozyten-ähnliche Zellen (MLO-Y4-Zellen) genutzt. In diesen wurde der Einfluss der Substanzen auf das RANKL/OPG-Verhältnis, als einen Marker der Osteoklastenfunktion, sowie auf Dickkopf-1, einen Inhibitor des Wnt-Signalwegs, getestet. Während PRED die totale und trabekuläre Knochendichte im Femur und der Wirbelsäule verminderte, zeigte CpdA keinen Einfluss auf diese Parameter. Diese Ergebnisse wurden durch die histomorphometrische Analyse bestätigt und zeigten des Weiteren, dass PRED die Mineralanbaurate reduzierte während es die Anzahl der Osteoklasten erhöhte. Die verminderte Osteoblastenfunktion ging mit einer Abnahme der Knochenformationsmarker im Serum und im Knochengewebe einher. Außerdem wurden der Resorptionsmarker im Serum und das RANKL/OPG-Verhältnis im Knochengewebe von PRED erhöht. Bei CpdA-behandelten Tieren wurden keine dieser Effekte beobachtet. Zudem wurde das RANKL/OPG-Verhältnis in vitro in MLO-Y4-Zellen durch CpdA nicht beeinflusst und auch die Transaktivierung von Dkk-1 im Knochengewebe, in Knochenmarkszellen und Osteozyten blieb aus, was somit eine mögliche Erklärung für die knochenschonende Wirkung von CpdA darstellen könnte. Um die entzündungshemmenden Eigenschaften von CpdA zu untersuchen, wurde mittels einer Kollageninjektion Arthritis in DBA/1-Mäusen induziert. Nachdem die Mäuse eine Arthritis entwickelt hatten, wurden sie jeden zweiten Tag über eine Dauer von zehn Tagen mit PBS (Vehikel), Dexamethason (DEX; 100 µg/Maus) oder CpdA (300 µg/Maus) behandelt. CpdA war in der Lage die Krankheitsaktivität, die Pfotendicke und die Pfotentemperatur zu senken. Dabei war es aber nicht so effektiv wie DEX. Außerdem konnte gezeigt werden, dass T-Zellen, die aus CpdA- und DEX- behandelten Tieren isoliert und mit Kollagen stimuliert wurden, basierend auf ihrer Proliferationsrate weniger aktiv waren und geringere Mengen an Interferon-γ produzierten, als T-Zellen, die aus PBS-behandelten Tieren entnommen wurden. Das schwächere entzündungshemmende Potenzial von CpdA, verglichen mit DEX, wurde mittels der histologischen Analyse der Gelenke bestätigt. Es konnte eine höhere Infiltration von Entzündungszellen, sowie eine erhöhte Osteoklastogenese und Knorpelzerstörung in CpdA-behandelten Tieren beobachtet werden. Obwohl CpdA nicht in der Lage war, vor dem entzündungsbedingten Knochenverlust zu schützen, verschlimmerte es weder den Knochenverlust, noch veränderte es die Knochendichte in gesunden Kontrollmäusen. Diese Studie zeigt das knochenschonende Potenzial von CpdA in einem Mausmodell des GC-induzierten Knochenverlustes und bestätigt die moderaten entzündungshemmenden Eigenschaften von CpdA in vivo. Trotz der knochenschonenden Effekte von CpdA in gesunden Mäusen wird sein Einsatz in der klinischen Praxis durch die schmale therapeutische Breite erschwert. Trotz alledem deutet unsere Studie mit CpdA auf wichtige molekulare Mechanismen hin. Somit könnte durch das Verhindern der Erhöhung des RANKL/OPG-Quotienten oder von Dkk-1 in osteogenen Zellen, der durch GC verursachte Knochenverlust möglicherweise verhindert werden.

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Ziel: Gewinnung neuer Erkenntnisse auf dem Gebiet der Glucocorticoidforschung. Die Arbeit gliedert sich in zwei Teile: 1. Klinische Studie zu Wirkungen und Nebenwirkungen einer niedrig bis mittelhoch dosierten Methylprednisolon(MP)-Therapie bei Patienten mit entzündlich-rheumatischen Erkrankungen. 2. Durchflusszytometrische Untersuchungen mit humanen PBMC mit dem Ziel, membranständige Glucocorticoidrezeptoren (mGCR) nachzuweisen. Methodik: 1. In einer klinischen Studie wurden zwei Patientengruppen mit jeweils 20 Patienten miteinander verglichen. Alle Patienten hatten entzündlich-rheumatische Erkrankungen und bekamen eine MP-Therapie über mindestens ein Jahr. Die Dosierungen in der ersten Gruppen entsprachen einer low-dose GC-Therapie, die Patienten in der zweiten Gruppe bekamen eine medium-dose GC-Therapie. Erwünschte, unerwünschte Wirkungen sowie die Lebensqualität der Patienten wurden erhoben. 2. Humane PBMC wurden durchflusszytometrisch untersucht. Es wurden konventionelle Färbemethoden sowie eine hoch-sensitive Liposomenfärbung zur Detektion spezifischer membranständiger Antigene angewandt. Ergebnisse: 1. In den meisten Fällen waren die relativ niedrigen Dosierungen von MP geeignet, die Krankheitsaktivität der entzündlich-rheumatischen Erkrankung wirksam zu kontrollieren. Einzelne Exazerbationen waren allerdings zu verzeichnen. Bei den meisten unerwünschten Wirkungen zeigten sich keine Unterschiede zwischen den Dosisgruppen. Osteoporosetypische Rückenschmerzen traten signifikant höher in der oberen Dosisgruppe auf (p=0,04), bei dem erhöhten Augeninnendruck zeigte sich eine Tendenz (p=0,1). Häufige Nebenwirkungen auch bei niedrigen Dosierungen waren: Unterblutungen der Haut und Pergamenthaut (76,2 % bzw. 73,8 % aller Patienten) bzw. eine Cushing-Symptomatik (61,9 % aller Patienten). 2. Mit der Liposomen-Färbetechnik ließen sich erstmals mGCR auf humanen PBMC systematisch nachweisen. Bis zu 5 % der B-Lymphozyten und bis zu 7 % der Monozyten exprimierten mGCR bei Gesunden. Stimulationen des Immunsystems durch Impfungen oder eine aktive rheumatoide Arthritis führten zu einer deutlichen Erhöhung des Anteils mGCR-positiver Monozyten auf über 20 %. Schlussfolgerungen: 1. Niedrig bis mittelhoch dosierte Therapien mit MP können effektiv die Aktivität von entzündlich-rheumatischen Erkrankungen kontrollieren. Die unerwünschten Effekte sind vermutlich dosisabhängig, für die meisten ist jedoch nicht relevant, ob mit einer low-dose oder einer medium-dose Therapie behandelt wird. 2. mGCR werden auf humanen PBMC unter physiologischen Bedingungen exprimiert. Unter bestimmten immunologischen Bedingungen werden sie hochreguliert. Herkunft und Funktion der Rezeptoren müssen noch genauer geklärt werden. / Purpose: Gaining new knowledge in glucocorticoid research. The dissertation consists of two parts: 1. Clinical study on effects and side-effects of a low-dose / medium-dose therapy with methylprednisolone (MP) in patients with inflammatory rheumatic diseases. 2. Flowcytometric investigation of human PBMC in order to detect membrane-bound glucocorticoid-receptors (mGCR). Methods: 1. In a clinical study two groups of patients - 20 patients each - were compared. All patients had inflammatory rheumatic diseases and recieved MP-therapy for at least one year. The first group recieved a low-dose GC-therapy, the second group a medium-dose GC-therapy. 2. Human PBMC were examined. We used conventional and high-sensitive liposome staining technique for the detection of specific membrane-bound antigens. Results: 1. In most cases rather low dosages of MP were able to control the disease activitiy of inflammatory rheumatic diseaeses. However, we observed disease exacerbation in some cases. Most side-effects showed the same characteristics in both groups. There was a significant higher appearance of typical osteoporotic back pain in the higher dosage group (p=0,04) and a tendency to higher intraophtalmic pressure in this group (p=0,1). Common side effects with even low dosages were: skin hematoma and thin skin (76,2 % and 73,8 % respective) and a Cushing-Syndrome (61,9 % of all patients). 2. With the liposome staining technique we showed for the first time systematically mGCR on human PBMC. Up to 5 % of B-lymphocytes and 7 % of monocytes presented mGCR in healthy blood donors. Stimulation of the immunological system by vaccination or in case of an active rheumatoid arthritis led to a marked increase of mGCR-positive monocytes to more than 20 %. Conclusions: 1. Low-dose and medium-dose methylprednisolone therapy can effectivly control the activity of inflammatory rheumatic diseases. The side effects are probably dose-dependent. However, for most side effects it doesn''t matter if patients are treated with a low-dose or a medium-dose therapy. 2. mGCR are expressed on human PBMC under physiological conditions and are up-regulated under certain immunological conditions. The function of these receptors has to be examined more profoundly.

Abstract Glucocorticoids are the most important and widely used treatment modality in dermatology. A large variety of topical as well as systemic preparations is available. Most patients treated with glucocorticoids respond quickly to the treatment, but some are considered insensitive or even resistant to glucocorticoid therapy. Currently, there is no known measurable variable, through which the response can be predicted. Glucocorticoids mediate their actions through glucocorticoid receptors (GR). Several isoforms of GR exist, but the α (GRα) and β (GRβ) isoforms are clinically the most important. Based on previous studies, it has been proposed that the abundance of GR isoforms or the GRβ: GRα –ratio could affect individual responsiveness to corticosteroid treatment. In particular, up-regulation of GRβ expression has been shown to be linked to resistance to corticosteroid treatment. This thesis comprises three sub-studies. Firstly, we wanted to determine whether GRα and GRβ are expressed in inflammatory skin diseases. Secondly, we examined if the expression is altered by corticosteroid treatment in eczema atopicum, bullous pemphigoid and psoriasis. Finally, we measured the effects of a topical vitamin D3 analogue (calcipotriol) combined with betamethasone compared with betamethasone monotherapy on inflammatory biomarkers of psoriasis. Our studies provide detailed novel data about the expression of GRα and GRβ. GRα and GRβ were shown to be expressed in the blood lymphocytes and lesional skin of patients with eczema atopicum, bullous pemphigoid and psoriasis, as well as in the skin of patients with eczema nummulare, lichen simplex chronicus and lichen ruber planus. Systemic corticosteroid treatment was shown to affect the expression of GRα and GRβ in eczema atopicum and bullous pemphigoid, but the inconsistent variation in their expression between patients prevented us from drawing firm conclusions. Neither GRα nor GRβ as a single marker were found to be a suitable predictor of corticosteroid responsiveness. Clinical and laboratory analyses showed that topical treatment of psoriasis with calcipotriol/betamethasone combination ointment is more beneficial measured by both than betamethasone monotherapy. / Tiivistelmä Glukokortikoideja (”kortisoni”) käytetään tulehduksellisten ihotautien hoidossa paikallisesti tai systeemisenä lääkkeenä. Suurin osa potilaista reagoi hoitoon nopeasti, mutta osalla hoitovaste on heikompi tai ilmenee hitaasti. Tällä hetkellä ei tunneta keinoja ennustaa luotettavasti kortisonihoidon vastetta. Glukokortikoidit vaikuttavat elimistössä glukokortikoidireseptorien (GR) kautta. Glukokortikoidireseptorista tunnetaan useita alatyyppejä, joista tärkeimmät ovat α (GRα) ja β (GRβ). Aiemman tiedon pohjalta on pidetty mahdollisena, että GR-alatyyppien suhteella tai määrällä on merkitystä kortisonivasteen syntymisessä. Erityisesti on arveltu, että ylimäärä GRβ:aa voisi estää kortisonihoidon vaikutusta. Tässä väitöskirjassa tavoitteena on ollut selvittää, tapahtuuko GR-alatyyppien ilmenemisessä muutoksia tulehduksellisia ihosairauksia sairastavilla potilailla sekä tutkia, miten kortisonihoito vaikuttaa GR-tasoihin atooppista ihottumaa, pemfigoidia ja psoriaasia sairastavilla potilailla. Lisäksi olemme verranneet paikallishoitoa pelkällä kortisonivoiteella D-vitamiinijohdos kalsipotriolin ja kortisonin yhdistelmähoitoon psoriaatikoilla. Tutkimus on antanut uutta yksityiskohtaista tietoa GRα:n ja GRβ:n esiintymisestä ihossa ja tulehdussoluissa ihosairauksia sairastavilla potilailla. Tutkimustulosten perusteella voidaan todeta, että GRα ja GRβ esiintyvät atooppista ihottumaa, pemfigoidia ja psoriaasia sairastavien potilaiden ihossa ja veren tulehdussoluissa sekä nummulaari-ihottumaa, neurodermatiittia ja punajäkälää sairastavien potilaiden ihossa. Suun kautta annettu kortisonihoito vaikuttaa GRα- ja GRβ–lähetti-RNA:n ilmenemiseen, mutta potilaskohtaiset erot ovat suuret, eikä kumpikaan, GRα tai GRβ, sovellu yksinään ennustamaan kortisonihoidon vastetta. Paikallisella kortisonihoidolla D-vitamiinijohdos kalsipotrioliin yhdistettynä on suotuisampi vaikutus psoriaasin tulehduksellisiin välittäjäaineisiin ja tulehdussoluihin kuin pelkällä paikallisella kortisonihoidolla.

BACKGROUND:The widespread utilization of organic compounds in modern society and their dispersion through wastewater have resulted in extensive contamination of source and drinking waters. The vast majority of these compounds are not regulated in wastewater outfalls or in drinking water while trace amounts of certain compounds can impact aquatic wildlife. Hence it is prudent to monitor these contaminants in water sources until sufficient toxicological data relevant to humans becomes available. A method was developed for the analysis of 36 trace organic contaminants (TOrCs) including pharmaceuticals, pesticides, steroid hormones (androgens, progestins, and glucocorticoids), personal care products and polyfluorinated compounds (PFCs) using a single solid phase extraction (SPE) technique with ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The method was applied to a variety of water matrices to demonstrate method performance and reliability.RESULTS:UHPLC-MS/MS in both positive and negative electrospray ionization (ESI) modes was employed to achieve optimum sensitivity while reducing sample analysis time (<20min) compared with previously published methods. The detection limits for most compounds was lower than 1.0 picogram on the column while reporting limits in water ranged from 0.1 to 15ng/L based on the extraction of a 1L sample and concentration to 1mL. Recoveries in ultrapure water for most compounds were between 90-110%, while recoveries in surface water and wastewater were in the range of 39-121% and 38-141% respectively. The analytical method was successfully applied to analyze samples across several different water matrices including wastewater, groundwater, surface water and drinking water at different stages of the treatment. Among several compounds detected in wastewater, sucralose and TCPP showed the highest concentrations.CONCLUSION:The proposed method is sensitive, rapid and robust / hence it can be used to analyze a large variety of trace organic compounds in different water matrixes.

Numerous epidemiological studies show a strong association between low birth weight and later life hypertension and metabolic disease. Excessive in utero exposure to glucocorticoids (‘stress hormones’) has been hypothesized to be important in such developmental ‘programming’, acting via crucial physiological, gene expression or structural changes in the developing fetus. Normally, the fetus is protected from the high levels of maternal glucocorticoids by an enzymic placental barrier, 11 betahydroxysteroid dehydrogenase type 2 (11β-HSD2). In the placenta, 11β-HSD2 efficiently converts active maternal glucocorticoids (cortisol in humans; corticosterone in rodents) to physiologically inactive 11-keto forms. In previous studies in rats, maternal administration of dexamethasone, a synthetic glucocorticoid which is minimally metabolized by 11β-HSD2, or carbenoxolone, a potent inhibitor of 11 β-hydroxysteroid dehydrogenase, increased glucocorticoid load to the fetus. This resulted in lower offspring birthweight and later life hypertension and hyperglycemia — important components of the metabolic syndrome. These programming effects were seen when dexamethasone was administered selectively during the third week of gestation. We have used this well-validated model of programming to dissect the molecular mechanisms that mediate the programming of hypertension. In accord with previous observations, administration of dexamethasone (100μg/kg/day) to pregnant rats during the last week of pregnancy significantly reduced offspring birthweight by 10%. Moreover, the 9 month-old adult offspring had systolic hypertension (9% rise) accompanied by significant hypokalemia (10% fall K+). The coexistence of hypertension and hypokalemia suggested that prenatal overexposure to dexamethasone might increase mineralocorticoid activity in the kidney. Intriguingly, although offspring of dexamethasone-treated dams had 46% lower plasma renin concentrations (consistent with intravascular fluid volume expansion), 24-hour total urinary aldosterone levels were significantly reduced compared to controls (reduction of 56%). Maternal dexamethasone treatment was associated with a permanent decrease in 11β- HSD2 mRNA and activity in the kidney of the offspring (45% and 36% respectively). 11β-HSD2 plays an important role in regulation of renal sodium reabsorption (and thereby blood pressure) by acting as a pre-receptor barrier to MR access, preventing glucocorticoids from activating MR in the distal nephron. Thus, the decrease in renal 11β-HSD2 activity would allow greater endogenous glucocorticoids to activate MR, likely accounting for the low-renin, low-aldosterone hypokalemic hypertensive phenotype observed in these offspring. Other components of mineralocorticoid or glucocorticoid signaling pathways, including mineralocorticoid receptor (MR), glucocorticoid receptor (GR) and 11-beta hydroxysteroid dehydrogenase type 1 (11β-HSD1) were not altered in the offspring kidney by prenatal glucocorticoid exposure. Dexamethasone-programmed offspring also showed exaggerated mineralocorticoid activity with increased kalliuresis in response to exogenously administered corticosterone, suggesting that the decrease in renal 11β-HSD2 is functionally important. In this respect, our rat model resembles the syndrome of apparent mineralocorticoid excess where reduced 11β-HSD2 allows illicit activation of MR by glucocorticoids, resulting in excessive sodium reabsorption, hypertension and hypokalemia. We also studied the effects of maternal dexamethasone on offspring erythropoietin expression in the kidney. This followed from previous observations that identified the hepatocyte nuclear factor 4 alpha (HNF4α) as a key gene up-regulated in dexamethasone-programmed offspring liver, where it might be involved in mediating hyperglycemia. HNF4α is also expressed in the kidney. The role of HNF4α in the kidney is not fully understood, but has been implicated in regulation of erythropoietin synthesis. As in the liver, prenatal exposure to dexamethasone caused a significant increase (64% increase) in renal HNF4α expression. The increase in renal HNF4α mRNA was observed early (in one week old offspring) and persisted into adulthood. This was associated with significantly elevated levels of erythropoietin in circulation (110% increase). Moreover, animals that were exposed to prenatal dexamethasone had significantly increased red blood cell mass (7% increase), presumably as a result of upregulation of erythropoietin.

L'axe hypothalamo-hypophyso-surrénalien (HPA) permet de maintenir l'homéostasie de l'organisme face à divers stress. Qu'ils soient de nature psychologique, physique ou inflammatoire/infectieux, les stress provoquent la synthèse et la libération de CRH par l'hypothalamus. Les cellules corticotropes hypophysaires perçoivent ce signal et en réaction, produisent et sécrètent l'ACTH. Ceci induit la synthèse des glucocorticoïdes (Gc) par le cortex surrénalien; ces stéroïdes mettent le système métabolique en état d’alerte pour la réponse au stress et à l’agression. Les Gc ont le rôle essentiel de contrôler les défenses de l'organisme, en plus d'exercer une rétro-inhibition sur l'axe HPA. L'ACTH est une petite hormone peptidique produite par le clivage d'un précurseur: la pro-opiomélanocortine (POMC). À cause de sa position critique dans la normalisation de l'homéostasie, le contrôle transcriptionnel du gène Pomc a fait l'objet d'études approfondies au cours des dernières décennies. Nous savons maintenant que la région promotrice du gène Pomc permet une expression ciblée dans les cellules POMC hypophysaires. L'étude du locus Pomc par des technologies génomiques m'a permis de découvrir un nouvel élément de régulation qui est conservé à travers l'évolution des mammifères. La caractérisation de cet enhancer a démontré qu'il dirige une expression restreinte à l'hypophyse, et plus particulièrement dans les cellules corticotropes. De façon intéressante, l'activité de cet élément dépend d'un nouveau site de liaison recrutant un homodimère du facteur de transcription Tpit, dont l'expression est également limitée aux cellules POMC de l'hypophyse. La découverte de cet enhancer ajoute une toute nouvelle dimension à la régulation de l'expression de POMC. Les cytokines pro-inflammatoires IL6/LIF et les Gc sont connus pour leur antagonisme sur la réaction inflammatoire et sur le promoteur Pomc via l'action des facteurs de transcription Stat3 et GR respectivement. L'analyse génomique des sites liés ii par ces deux facteurs nous a révélé une interrelation complexe et a permis de définir un code transcriptionnel entre ces voies de signalisation. En plus de leur action par interaction directe avec l’ADN au niveau des séquences régulatrices, ces facteurs interagissent directement entre eux avec des résultats transcriptionnels différents. Ainsi, le recrutement de GR par contact protéine:protéine (tethering) sur Stat3 étant lié à l'ADN provoque un antagonisme transcriptionnel. Inversement, le tethering de Stat3 sur GR supporte une action synergique, tout comme leur co-recrutement à l'ADN sur des sites contigus ou composites. Lors d'une activation soutenue, ce synergisme entre les voies IL6/LIF et Gc induit une réponse innée de défense cellulaire. Ainsi lors d'un stress majeur, ce mécanisme de défense est mis en branle dans toutes les cellules et tissus. En somme, les travaux présentés dans cette thèse définissent les mécanismes transcriptionnels engagés dans le combat de l'organisme contre les stress. Plus particulièrement, ces mécanismes ont été décrits au niveau de la réponse globale des corticotropes et du gène Pomc. Il est essentiel pour l'organisme d'induire adéquatement ces mécanismes afin de faire face aux stress et d'éviter des dérèglements comme les maladies inflammatoires et métaboliques. / The hypothalamo-pituitary-adrenal (HPA) axis regulates homeostasis in various conditions of stress contributing to both the stress response and its termination. Psychological, physical or inflammatory/infectious stresses all prompt the synthesis and secretion of hypothalamic CRH. The pituitary corticotrope cells receive this signal and in turn, secrete ACTH which triggers the synthesis of glucocorticoids (Gc) by the adrenal cortex; these steroids induce a general state of alertness in order to fight or flight aggressions and stresses. Glucocorticoids have the critical role to restrict the stress response by exerting a negative feedback on the HPA axis. ACTH is a small peptidic hormone produced after cleavage of a precursor protein: pro-opiomelanocortin (POMC). Due to its critical role in homeostasis, transcriptional control of the Pomc gene has been intensely studied during the last decades. Previous investigations identified a promoter region that is sufficient for expression of Pomc in the appropriate pituitary cells. Genome-wide studies of the Pomc locus led me to discover a novel regulatory element that is conserved throughout mammalian evolution. The activity of this enhancer is restricted to the pituitary, and more precisely to the corticotrope lineage. Interestingly, its activity depends on a novel transcription factor binding motif that binds homodimers of Tpit, a transcription factor that is only found in pituitary POMC cells. The discovery of this enhancer adds a new dimension in the control of pituitary Pomc expression. The IL6/LIF pro-inflammatory cytokines and the glucocorticoids are well known for their antagonism in control of the inflammatory response; at the Pomc promoter, their action is mediated by the transcription factors Stat3 and GR, respectively. The analysis of genomic sites bound by these two factors revealed a complex relationship and led us to define a transcription regulatory code linking these signalling pathways. In addition to their direct DNA interaction with cognate regulatory sequences, these factors iv interact with each other with different outcomes. Thus, the recruitment of GR on DNAbound Stat3 through protein:protein contacts (tethering) results in transcriptional antagonism. Conversely, Stat3 tethering to GR produces synergism; this is also the case when the two factors are co-recruited to DNA on contiguous or composite binding sites. Prolonged activation of the IL6/LIF and Gc pathways elicits a synergistic innate cell defense response in all cells and tissues. In summary, this doctoral work has defined transcriptional mechanisms that mediate and control the stress response. In particular, pituitary components of the stress response were defined at the level of the Pomc gene and as a global response of corticotrope cells. This response is critical for appropriate organism defense during stresses such as those produced in inflammatory and metabolic diseases.