Toll-like Rezeptoren (TLR) und Nod-like Rezeptoren (NLR) sind Muster-erkennende Rezeptoren des angeborenen Immunsystems, die bakterielle Zellwandbestandteile erkennen können. Interleukin (IL)-1beta ist ein streng reguliertes Zytokin. Durch eine erste Stimulation wird der TLR-Rezeptor ausgelöst und führt zur Expression des Vorläuferproteins proIL-1beta. Durch einen zweiten Stimulus wird ein zytoplasmatischer NLR-Rezeptor zur Caspase1-Aktivierung angeregt. Dies führt zur post-translationalen Reifung von proIL-1beta zu reifem IL-1beta und zur Aktivierung weiterer Mechanismen der Pathogen-Eliminierung während einer bakteriellen Meningitis. Im ersten Teil dieser Arbeit wurde die synergistische Beziehung zwischen TLRs und NOD2 in Bezug auf die IL-1beta-Sekretion in Astrozyten und Mikroglia untersucht. Primäre murine WT-Astrozyten und eine humane Zelllinie, die mit Lipopolysaccharid (LPS) oder Lipopeptid sowie Muramyldipeptid (MDP) stimuliert wurden, zeigten signfikant erhöhte IL-1beta-Werte. IL-1beta war in NOD2-/- Astrozyten nicht erhöht. NOD2 trägt demnach als MDP-ausgelöster Rezeptor in Astrozyten, vermutlich zusammen mit dem Inflammasom-Komplex, zur Caspase-1-Aktivierung bei. In Mikrogliazellen lässt sich der bei Astrozyten gezeigte Effekt nicht reproduzieren. Zum ersten Mal wurde gezeigt, dass die TLR-abhängige IL-1beta-Antwort durch NOD2-Beteiligung in murinen und humanen Astrozyten synergistisch erhöht wird. In einem weiteren Versuchsteil wurde in primären murinen Peritonealmakrophagen von adulten Mäusen der TLR/NLR-Synergismus untersucht. Es stellte sich überraschenderweise heraus, dass weibliche NOD2-/- Mäuse zu einer synergistisch erhöhten IL-1beta-Sekretion fähig waren. SiRNA-Versuche mit in Östrogen vorinkubierten RAW264.7-NOD2-/- Zellen zeigten eine eindeutige Synergie der TLR4- und NOD2-Rezeptoren in der IL-1beta-Ausschüttung. Östrogen scheint weiblichen Individuen einen protektiven Vorteil vor Infektionen bei NOD2-Defizienz zu verschaffen. / Toll-like receptors (TLR) and nod-like receptors (NLR) are pattern-recognition receptors that recognize lipopolysaccharide (LPS), lipopeptides and myramyldipeptide (MDP) derived from bacterial cell wall. We focus our question on the regulation of the pro-inflammatory cytokine interleukin (IL)-1beta during bacterial meningitis in primary murine astrocytes and microglia as well as cell lines and the synergism of TLR4 or TLR2 and NOD2 to amplify IL-1beta-expression. ProIL-1beta is expressed by TLR-stimulation and activation of NF-kB signal transduction. Through the activation of Caspase-1, possibly through NOD2 and the inflammasome, proIL-1beta is cleaved on post-translational level and obtains its activated status, leading to pathogen elimination during bacterial meningitis. Primary murine WT-astrocytes and a human cell line primed with LPS or lipopeptide and stimulated with MDP show significantly increased IL-1beta levels in the supernatant. NOD2-/- astrocytes do not show elevated IL-1beta levels. After screening of cytoplasmic proCaspase-1 and activated Caspase-1 by Western blot it became clear, that stimulation of NOD2 with MDP led to Caspase-1 activation and thus to IL-1beta maturation in primary murine WT-astrocytes. We demonstrate for the first time that the synergism between TLR4 and NOD2 leads to significantly elevated IL-1beta levels and that NOD2 is capable of activating caspase-1 in primary murine astrocytes. Another part of the work was to test the TLR/NLR-synergism on primary peritoneal macrophages from adult mice. Surprisingly, female NOD2-/- mice showed significantly elevated IL-1beta levels. SiRNA- and stimulation-experiments with RAW264.7-NOD2-/- cells pre-incubated in estrogen show a clear synergy in IL-1beta secretion through TLR4 and NOD2 receptors. Estrogen seems to protect females from infection when having a NOD2 deficiency.

Le Syndrome de Détresse Respiratoire Aiguë (SDRA) est une maladie inflammatoire courante en service de réanimation qui touche environ 10% des patients. Une augmentation pathologique de la rigidité et/ou de l'adhésion des leucocytes des patients atteints du SDRA semble être un des facteurs déclenchants majeurs de la maladie. Nous avons utilisé la microfluidique pour mimer le passage des cellules dans les capillaires pulmonaires. L'observation du passage de cellules modèles (lignée monocytaire humaine THP-1) dans des constrictions microfluidiques (H=12µm et W=6µm) a permis de mesurer leur temps d'entrée. Ensuite nous avons incubé des cellules dans des sérums issus de malades et étudié leurs caractéristiques de passage dans des constrictions microfluidiques en fonction du temps d'incubation et de la concentration en sérum. Ces résultats sont ensuite comparés à la composition des sérums en cytokines (IL-1β, IL-6, IL-8, IL-10, IL-17, TNF-α, TGF-β et INF-γ). Des corrélations entre l'IL-8, IL-1β, le TNF-α et le temps d'entrée ont été trouvés. Ces deux cytokines peuvent jouer un rôle dans la rigidité cellulaire lors de cette maladie. En incubant ainsi nos cellules avec les recombinants humains (IL-8, IL-1β et Tnf-α), nous avons constaté une augmentation de la rigidité des cellules. D'un point de vue médical nous avons montré que l'utilisation d'anticorps bloquants anti IL-8, anti IL-1β et anti TNF-α permet de protéger les cellules. / The project consists in using microfluidic devices to test human leukocyte behavior in microcirculation. Adult Respiratory Distress Syndrome (ARDS) is a disease that affects numerous patients in intense care services with a rate of death 50%. It is triggered to the sequestration of neutrophils within the lung microvasculature. There is neither diagnostic nor efficient treatment now. We study the properties of the passage of THP-1, and real neutrophils in micro-channels of width 6µm. In order to improve the understanding of SDRA, we also incubate models cells in patient's serums who are suffering from ARDS and diagnostic tools are being developed in collaboration with the hospitals of Marseille.

Melanoma, a forma mais agressiva de câncer de pele, é um tumor maligno dos melanócitos. Além dos riscos ambientais tais como a radiação UV e fenótipo de pele do indivíduo, a genética também tem sido descrita como um fator de risco para o desenvolvimento de melanoma. Recentemente foi relatado que a malignidade do melanoma está diretamente relacionada com a secreção constitutiva da citocina inflamatória IL-1? em melanócitos transformados, sugerindo o envolvimento do inflamassoma na progressão tumoral. Com a finalidade de avaliar se a genética do inflamassoma poderia contribuir para a susceptibilidade ao desenvolvimento do melanoma maligno esporádico no presente trabalho analisamos 10 polimorfismos de nucleotídeos únicos (SNPs) em cinco genes do inflamassoma (NLRP1, NLRP3, CARD8, IL1B, IL18) numa coorte brasileira caso/controle de melanoma. Além disso, a expressão de genes do inflamassoma foi avaliada em biópsias de tumores de melanomas e nevos benignos. Para tanto recrutamos 198 pacientes de melanoma e 142 doadores saudáveis. As biópsias de tumores/nevos foram obtidas de 15 dos 198 pacientes de melanoma e de cinco dos 142 controles saudáveis, respectivamente. Utilizamos a técnica de PCR em tempo real com alelo e sondas específicas em ensaios com TaqMan® para os ensaios de genotipagem de amostras de DNA dos casos/controles de melanoma e para estudos de expressão de genes específicos do inflamassoma, em amostras de biopsias de tumores e nevos, respectivamente. Verificamos que o SNP rs6509365 em CARD8 foi significativamente mais comum em controles saudáveis do que em pacientes de melanoma, sugerindo um efeito protetivo da variante para o desenvolvimento de melanoma. Corroborando com este achado, a expressão de CARD8 foi encontrada aumentada em biópsias de melanoma em comparação com a expressão em nevo. Além disso, a estratificação dos dados mostrou que a variante rs11651270 em NLRP1 associada com melanoma nodular; rs1143643 em IL1B, amplificado em níveis baixos, foi associado com invasividade (índice de Breslow) e rs5744256 em IL18 foi associado com desenvolvimento de melanoma em pessoas sensíveis ao sol. A análise em biópsias dos tumores ainda mostrou que a expressão de IL-1beta foi regulada positivamente, especialmente em amostras de indivíduos que apresentaram metástases, enquanto que IL-18 foi negativamente regulada comparada com a expressão em nevos. Em conjunto nossos resultados demonstram, pela primeira vez, a contribuição dos genes do inflamassoma CARD8, IL1B e IL18 ao melanoma / Melanoma, the most aggressive form of skin cancer, is a malignant melanocyte tumor. In addition to environmental risks such as UV radiations, individual\'s skin phenotype and genetics has also been described as potential risk factors for the development of melanoma. It has recently been reported that malignant melanoma is directly related to the constitutive secretion of the inflammatory cytokine, IL-1?, in transformed melanocytes suggesting the involvement of the inflammasome in tumor progression. In order to evaluate if the genetics of the inflammasome could contribute to the susceptibility to the development of malignant melanoma, we analyzed 10 single nucleotide polymorphisms (SNPs) in five inflammation related genes (NLRP1, NLRP3, CARD8, IL1B, IL18) in a case/control Brazilian cohort of melanoma. In addition, the expression of inflammatory genes was evaluated in biopsies of melanoma and nevus tumors. We recruited 198 melanoma patients and 142 healthy donors. Tumor/nevus biopsies were obtained from 15 of 198 melanoma patients and five of 142 healthy controls, respectively. We used the real-time PCR technique for specific allele with specific probes using TaqMan ® assays for genotyping of DNA samples from melanoma cases/controls and for studies of expression of specific genes of inflammasome from RNA samples of tumor biopsy and nevus, respectively. We have found that SNP rs6509365 in CARD8 was significantly more common in healthy controls than in melanoma patients, suggesting a protective effect of this variant for the development of melanoma. Corroborating this finding, CARD8 expression was found to be increased in melanoma biopsies compared to nevus expression. In addition, stratification of the data showed that variant rs11651270 in NLRP1 was associated with nodular melanoma; rs1143643 in IL1B at low levels was associated with invasiveness (Breslow score) and rs5744256 in IL18 was associated with melanoma development in sun sensitive individuals. Biopsy analysis of tumors further showed that IL-1? expression was up-regulated, especially in samples from individuals who had metastases, whereas IL-18 was down-regulated compared to expression in nevus. Together our results demonstrated for the first time the contribution of the inflammation related genes CARD8, IL1B and IL18 to melanoma

Melanoma, a forma mais agressiva de câncer de pele, é um tumor maligno dos melanócitos. Além dos riscos ambientais tais como a radiação UV e fenótipo de pele do indivíduo, a genética também tem sido descrita como um fator de risco para o desenvolvimento de melanoma. Recentemente foi relatado que a malignidade do melanoma está diretamente relacionada com a secreção constitutiva da citocina inflamatória IL-1? em melanócitos transformados, sugerindo o envolvimento do inflamassoma na progressão tumoral. Com a finalidade de avaliar se a genética do inflamassoma poderia contribuir para a susceptibilidade ao desenvolvimento do melanoma maligno esporádico no presente trabalho analisamos 10 polimorfismos de nucleotídeos únicos (SNPs) em cinco genes do inflamassoma (NLRP1, NLRP3, CARD8, IL1B, IL18) numa coorte brasileira caso/controle de melanoma. Além disso, a expressão de genes do inflamassoma foi avaliada em biópsias de tumores de melanomas e nevos benignos. Para tanto recrutamos 198 pacientes de melanoma e 142 doadores saudáveis. As biópsias de tumores/nevos foram obtidas de 15 dos 198 pacientes de melanoma e de cinco dos 142 controles saudáveis, respectivamente. Utilizamos a técnica de PCR em tempo real com alelo e sondas específicas em ensaios com TaqMan® para os ensaios de genotipagem de amostras de DNA dos casos/controles de melanoma e para estudos de expressão de genes específicos do inflamassoma, em amostras de biopsias de tumores e nevos, respectivamente. Verificamos que o SNP rs6509365 em CARD8 foi significativamente mais comum em controles saudáveis do que em pacientes de melanoma, sugerindo um efeito protetivo da variante para o desenvolvimento de melanoma. Corroborando com este achado, a expressão de CARD8 foi encontrada aumentada em biópsias de melanoma em comparação com a expressão em nevo. Além disso, a estratificação dos dados mostrou que a variante rs11651270 em NLRP1 associada com melanoma nodular; rs1143643 em IL1B, amplificado em níveis baixos, foi associado com invasividade (índice de Breslow) e rs5744256 em IL18 foi associado com desenvolvimento de melanoma em pessoas sensíveis ao sol. A análise em biópsias dos tumores ainda mostrou que a expressão de IL-1beta foi regulada positivamente, especialmente em amostras de indivíduos que apresentaram metástases, enquanto que IL-18 foi negativamente regulada comparada com a expressão em nevos. Em conjunto nossos resultados demonstram, pela primeira vez, a contribuição dos genes do inflamassoma CARD8, IL1B e IL18 ao melanoma / Melanoma, the most aggressive form of skin cancer, is a malignant melanocyte tumor. In addition to environmental risks such as UV radiations, individual\'s skin phenotype and genetics has also been described as potential risk factors for the development of melanoma. It has recently been reported that malignant melanoma is directly related to the constitutive secretion of the inflammatory cytokine, IL-1?, in transformed melanocytes suggesting the involvement of the inflammasome in tumor progression. In order to evaluate if the genetics of the inflammasome could contribute to the susceptibility to the development of malignant melanoma, we analyzed 10 single nucleotide polymorphisms (SNPs) in five inflammation related genes (NLRP1, NLRP3, CARD8, IL1B, IL18) in a case/control Brazilian cohort of melanoma. In addition, the expression of inflammatory genes was evaluated in biopsies of melanoma and nevus tumors. We recruited 198 melanoma patients and 142 healthy donors. Tumor/nevus biopsies were obtained from 15 of 198 melanoma patients and five of 142 healthy controls, respectively. We used the real-time PCR technique for specific allele with specific probes using TaqMan ® assays for genotyping of DNA samples from melanoma cases/controls and for studies of expression of specific genes of inflammasome from RNA samples of tumor biopsy and nevus, respectively. We have found that SNP rs6509365 in CARD8 was significantly more common in healthy controls than in melanoma patients, suggesting a protective effect of this variant for the development of melanoma. Corroborating this finding, CARD8 expression was found to be increased in melanoma biopsies compared to nevus expression. In addition, stratification of the data showed that variant rs11651270 in NLRP1 was associated with nodular melanoma; rs1143643 in IL1B at low levels was associated with invasiveness (Breslow score) and rs5744256 in IL18 was associated with melanoma development in sun sensitive individuals. Biopsy analysis of tumors further showed that IL-1? expression was up-regulated, especially in samples from individuals who had metastases, whereas IL-18 was down-regulated compared to expression in nevus. Together our results demonstrated for the first time the contribution of the inflammation related genes CARD8, IL1B and IL18 to melanoma

Das Ziel dieser Arbeit war die Darstellung der Einflüsse verschiedener Interleukine auf die HDGF-Expression in verschiedenen Kolonzelllinien. HDGF stellt einen Wachstumsfaktor dar, der nicht nur physiologisch bei der Entwicklung einiger Gewebe wie der Niere, der Leber und des Darms von Be-deutung ist, sondern auch eine wichtige Rolle in der Karzinogenese verschie-dener Tumoren spielt. Hierzu zählen unter anderem das hepatozelluläre Karzi-nom, das NSCLC und das Melanom. Von besonderer Relevanz ist seine Rolle in der Pathogenese des kolorektalen Karzinoms. Die verwendeten Interleukine (1beta, 4, 5, 8 und 13) zeigen sowohl inhibierende als auch fördernde Eigenschaften in Bezug auf die Karzinogenese von kolorektalen Tumoren. Dies steht im Einklang mit früheren Resultaten der Literatur. Die vier verschiedenen Zelllinien, eine Adenomzelllinie, zwei Adenokarzinomzelllinien sowie eine Zelllinie aus Lymphknotenmetastasenzellen wurden mit den verschiedenen Interleukinen inkubiert und mittels REAL TIME-RT-PCR analysiert. Die Ergebnisdarstellung in Blockdiagrammen zeigt semiquantitativ die relative HDGF-Expression. So lassen sich Aussagen über Anstieg oder Abfall der Expression durch den Einfluss der verschiedenen Interleukine machen. Die hier gezeigten Ergebnisse lassen, wie auch schon teilweise in der Literatur beschrieben, für alle Interleukine außer für IL 1beta, sowohl hemmende als auch tumorunterstützende Effekte beobachten. Interleukin 1beta zeigt in Kongruenz der vorbeschriebenen Studien, im Gegensatz zu den anderen Zytokinen, in allen Zelllinien tumorfördernde Eigenschaften. Für IL 4 ist zunächst in den Adenomzellen ein antitumoröser Effekt zu erkennen, dieser kehrt sich in der Metastasenzelllinie in eine förderndene Wirkung um. In den Adenokarzinomzelllinien sind weder eindeutige suppressive noch unterstützende Wirkungen zu verzeichnen. Über einen Zusammenhang zwischen dem Grad der malignen Transformation und unterschiedlichem Ansprechen auf IL 4 lässt sich jedoch bisher nur spekulieren. Für IL 5 ist ein ähnliches Verhalten zu beobachten. Eine anfängliche inhibitorische Wirkung auf die HDGF-Expression in den Adenomzellen sowie Adenokarzinomzellen kehrt sich in der Metastasenzelllinie in den gegenteiligen Effekt um. Auch hier lässt sich eine Umkehr der ausgelösten Effekte mit fortschreitender maligner Transformation vermuten. IL 8 zeigt kongruente Effekte zu IL 4 und IL 5, jedoch lassen sich für IL 8 in der Literatur bisher nur tumorunterstützende Wirkungen finden. Hier lässt sich in den Adenomzellen eine suppressive Wirkung verzeichnen, wohingegen in den beiden Adenokarzinomzelllinien fördernde Effekte beobachtet werden. In der Metastasenzelllinie lassen sich jedoch weder positive noch negative Auswirkungen feststellen. Des Weiteren spiegeln auch die Ergebnisse des Einflusses von IL 13 die Vielgestaltigkeit der Wirkweisen dieses Interleukins dar, mit tumorhemmenden Effekten in den Adenom- sowie Metastasenzellen und fördernder Wirkung in den HT29-Zellen. Über die genauen Mechanismen, inwiefern ein Interleukin die Expression von HDGF hochreguliert oder supprimiert, kann zum momentanen Zeitpunkt nur spekuliert werden. Es kann jedoch vermutet werden, dass ein gewisser Zu-sammenhang zwischen dem Grad der malignen Transformation und der Wirk-weise der Interleukine existiert. Entscheidend sind hier sicherlich klonal erwor-bene Alterationen einzelner Signalkaskaden. Festzuhalten ist zum einen, dass bis auf IL 1beta für alle Zytokine der Einfluss auf HDGF vom jeweiligen Zellsystem abhängt. Diese Ergebnisse machen eine Schlüsselrolle von HDGF eher unwahrscheinlich, vielmehr scheint seine Regulation hier in teilweise komplexe Regulationsmechanismen mit eingebunden zu sein. Dass diese Alterationen möglicherweise auch im Rahmen der Karzinogenese bzw. der Akquise der Metastasierungsfähigkeit entstehen könnten, zeigen die teilweise bestehenden Unterschiede zwischen der verwendeten Adenomzelllinie und den Karzinomzelllinien respektive zwischen Karzinom- und Metastasenzelllinie. Die beschriebenen Ergebnisse geben einen Anhaltspunkt, in welche Richtung die einzelnen Interleukine wirken, zumindest in wie weit hier ein Einfluß auf die Transkription von HDGF als Surrogatmarker der Mitogenese erfolgt. Um die Komplexität und Vielfalt der Effekte von Interleukinen in Bezug zu Tumorstadium, Invasivität sowie Metastasierungsfähigkeit in Einklang zu bringen, bedarf es jedoch weiterführender Studien. Es lies sich zeigen, dass die angewendeten Interleukine generell Einfluss auf die Expressionshöhe von HDGF in verschiedenen Kolonzelllinien haben und als exogene Faktoren in die Regulation eingreifen können. Dies könnte ein weiterer Ansatz zur Etablierung immunmodulatorischer Therapieoptionen in soliden Neoplasien in der Zukunft sein. / Hepatoma-derived growth factor (HDGF) is a growth factor which plays a role in physiological development of some organ tissues and in the carcinogensis of a few tumors like colorectal cancer, hepatocellular cancer, NSCLC. For this study especially the role of HDGF with regard to colorectal cancer is important. The main focus is set on the influences that different interleukins have on the expression of HDGF in different gut-tissues and colon cancer-tissues. To this end, five interleukins (1beta, 4, 5, 8 and 13) with different effects on the carcinogenesis of colorectal cancer (inhibition/promotion) were investigated. It is known from the literature that all five interleukins show different behavior. Four cell lines–one adenoma cell line, two different cell lines of adenoma carcinoma of intestine, one cell line of lymph node metastase of adenoma carcinoma of intestine–were incubated with the five interleukins and analyzed with Real Time-RT-PCR. This method allows for an observation of changes of the relative HDGF-expression. The results show that all interleukins have an influence on the HDGF-expression. The most pronounced effects are observed in dependency of the concentration of the interleukins under investigation. Interleukin 1beta exhibits throughout a tumor supporting behavior. In contrast to this, all other interleukins showed that their influence depends on the probed cell line. This suggests that there is a connection between the effect of the interleukin and the degree of malign differentiation. This complex interplay manifests itself, for instance, in a totally inversion of the effects, with depression of the HDGF-expression in the cell line of adenoma and a promotion in the cell line of metastasis in some experimental runs. These findings are partly concurrent with known properties described in the literature related to colorectal cancer. ln summary the results show that interleukins as exogenous factor can influence the HDGF-expression. However, the data do not allow to derive final statements on the mechanism of regulation. It is imaginable that an alteration of the signal pathways, presumably acquired clonal, determine whether an interleukin shows effects of inhibition or promotion on the cell lines. Therefore, further studies are required to clarify in how far interleukins influence the HDGF-expression.

IL-1α and IL-1β are two IL-1 agonists which signals at the same receptor complex composed of IL-1R1/IL-1RAcP. However, IL-1α and IL-1β exert differential actions. A recent CNS-specific IL-1 receptor accessory protein, called IL-1RAcPb, has been characterised but its actions are unknown. In T cell line, over expression of IL-1RAcPb negatively regulate IL-1 action (Smith et al, 2009), but over-expression of IL-1RAcPb in HEK cell line induces IL-1 signaling (Lu et al, 2008). The role of IL-1RAcPb has not been studied in primary cells. The aim of this project was to investigate the role of IL-1RAcPb in IL-1-induced actions in neurones and glia, and to determine IL-1α and IL-1β differential actions in these two cell types. The role of IL-1RAcPb in IL-1-induced protein expression and IL 1α and IL-1β differential effects were investigated by treating WT and IL 1RAcPb-/- neurones and glia with IL-1α or IL-1β in the presence or absence of IL-1RA for 24 h followed by assessment of IL-6 induction by ELISA. The mechanism of IL-1RAcPb actions were studied by examining the effects of IL-1α or IL-1β on p38, ERK1/2 and Src kinase activation in neurones and glia by Western blot analysis. SB203580 (p38 inhibitor), UO126 (ERK1/2 inhibitor), and PP2 (Src kinase inhibitor) were used to determine the contribution of p38, ERK1/2 and Src kinase activation to IL-1-induced IL-6 synthesis in neuronal cultures. In WT neurones, IL-1α and IL-1β were equipotent at inducing IL-6 synthesis and p38 activation, whilst both ligands failed to induce ERK1/2 or Src kinase activation. In IL-1RAcPb-/- neurones, IL-1α and IL-1β induced similar levels of IL-6, but IL-1β was more potent than IL-1α at inducing p38 activation. IL-1α-induced p38 activation was reduced in IL-1RAcPb-/- neurones compared to WT neurones. In contrast to WT neurones, ERK1/2 was activated in IL-1RAcPb-/- neurones in response to IL-1α, whilst Src kinase was not activated by IL-1α or IL 1β. IL-1-induced IL-6 synthesis was abolished by IL-1RA, SB203580, UO126 and PP2. Interestingly PP2, a specific Src kinase inhibitor also partially inhibited basal ERK1/2 activity. In WT glial cells, IL-1α was more potent than IL-1β at inducing IL-6 synthesis but both cytokines induced ERK1/2 activation with equal potency. In IL-1RAcPb-/- glia, IL-1α and IL-1β were equally potent at inducing IL-6 synthesis and ERK1/2 activation. However, IL-α-induced-IL-6 synthesis was reduced in IL 1RAcPb-/- glia compared to WT glia. In both WT and IL-1RAcPb-/- glia, IL-1α and IL-1β induced p38 activation but not Src kinase activation . In conclusion, this study showed that in neurones, IL-1RAcPb may contribute to IL-1α-induced p38 activation but negatively regulates IL-1-induced ERK1/2 activation, therefore IL-1RAcPb may have specific effects on different signalling pathways. The effect of IL-1RAcPb could also be cell specific, as IL 1RAcPb contributed to IL-1α-induced p38 signalling in neurones but IL-6 production in glia. The role of IL-1RAcPb remains largely unknown and more investigations are required to elucidate its role in IL-1 signalling in the brain.

The worldwide prevalence of obesity and metabolic disease is increasing at an exponential rate and current projections provide no indication of relief. This growing burden of obesity-related metabolic disorders, including type 2 diabetes mellitus (T2DM), highlights the importance of identifying how lifestyle choices, genetics and physiology play a role in metabolic disease and place obese individuals at a greater risk for obesity-related complications including insulin resistance (IR). This increased risk of IR, which is characterized by a decreased response to insulin in peripheral tissues including adipose tissue (AT) and liver, is associated with a chronic, low grade inflammatory state; however, the causative connections between obesity and inflammation remains in question. Experimental evidence suggests that adipocytes and macrophages can profoundly influence obesity-induced IR because adipocyte dysfunction leads to ectopic lipid deposition in peripheral insulin sensitive tissues, and obese AT is characterized by increased local inflammation and macrophage and other immune cell populations. Attempts to delineate the individual roles of macrophage-derived pro-inflammatory cytokines, like tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β), have demonstrated causative roles in impaired systemic insulin sensitivity, adipocyte function and hepatic glucose and lipid metabolism in obese animal models. Thus, the attenuation of macrophage-derived inflammation is an evolving area of interest to provide insight into the underlying mechanism(s) leading to obesity-induced IR. Thus, in the first chapter of this thesis, I describe experiments to refine the current paradigm of obesity-induced AT inflammation by combining gene expression profiling with computational analysis of two anatomically distinct AT depots, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) to address whether the inflammatory signature of AT is influenced by diet-induced obesity (DIO). Microarray and qRT-PCR analysis data revealed that DIO mouse SAT is resistant to high fat diet (HFD)-induced inflammation and macrophage infiltration, and our data support the current model of obesity-induced visceral adipose tissue macrophage (VATM) enrichment. Our data demonstrated robust increases in VAT pro-inflammatory cytokine expression, which are consistent with the significant increases in macrophage-specific gene expression and consistent with previous reports in which VAT inflammation is enhanced and attributed to classically activated (M1) macrophage infiltration. However, these data are only observed relative to the expression of invariant housekeeping gene expression. When M1-specific genes are expressed relative to macrophage-specific standards like F4/80 expression, these inflammatory makers are unchanged. These data indicate that the changes in the overall inflammatory profile of DIO mouse VAT is because of quantitative changes in adipose tissue macrophage (ATM) number and not qualitative changes in activation state. These observations are consistent with the idea that infiltrating ATMs may have roles other than the previously described role in mediating inflammation in obese adipose tissue. Hepatic IR occurs partly as a consequence of adipocyte dysfunction because the liver becomes a reservoir for AT-derived fatty acids (FAs), which leads to obesity-related non-alcoholic fatty liver disease (NAFLD). In the second part of my thesis, I used clodronate liposome-mediated macrophage depletion to define the role of macrophages in hepatic lipid metabolism regulation. We discovered that i.p. administration of clodronate liposomes depletes Kupffer cells (KCs) in ob/ob mice without affecting VATM content, whereas clodronate liposomes depletes both KCs and VATMs in DIO mice. To this end, we established that clodronate liposome-mediated KC depletion, regardless of VATM content in obese mice, abrogated hepatic steatosis by reducing hepatic de novo lipogenic gene expression. The observed reductions in hepatic inflammation in macrophage-depleted obese mice led to the hypothesis that IL-1β may be responsible for obesity-induced increased hepatic triglyceride (TG) accumulation. We determined that IL-1β treatment increases fatty acid synthase (Fas) protein expression and TG accumulation in primary mouse hepatocytes. Pharmacological inhibition of interleukin-1 (IL-1) signaling by interleukin-1 receptor antagonist (IL-1Ra) administration recapitulated these results by reducing hepatic TG accumulation and lipogenic gene expression in DIO mice. Thus, these data highlight the importance of the inflammatory cytokine IL-1β in obesity-driven hepatic steatosis and suggests that liver inflammation controls hepatic lipogenesis in obesity. To this end, the studies described herein provide new insight and appreciation to the multi-functional nature of macrophages and clinical implications for anti-inflammatory therapy in obesity and NAFLD treatment. We demonstrate the complexities of macrophage-mediated functions in insulin sensitive tissues and a role for obesity-induced inflammatory cytokine IL-1β in hepatic lipid metabolism modulation, which is reversed via IL-1Ra intervention. The use of anti-inflammatory therapy to ameliorate obesity-associated NAFLD was perhaps the most important contribution to this body of work and is full of promise for future clinical application. It is likely that the future of therapeutics will be multi-faceted and combine therapeutic approaches to enhance glucose tolerance and overall health in obese, IR and T2DM patients.

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