No / The interleukin-2-deficient (IL-2¿/¿) mouse model of ulcerative colitis was used to test the hypothesis that colonic epithelial cells (CEC) directly respond to bacterial antigens and that alterations in Toll-like receptor (TLR)-mediated signaling may occur during the development of colitis. TLR expression and activation of TLR-mediated signaling pathways in primary CEC of healthy animals was compared with CEC in IL-2¿/¿ mice during the development of colitis. In healthy animals, CEC expressed functional TLR, and in response to the TLR4 ligand LPS, proliferated and secreted the cytokines IL-6 and monocyte chemoattractant protein-1 (MCP-1). However, the TLR-responsiveness of CEC in IL-2¿/¿ mice was different with decreased TLR4 responsiveness and augmented TLR2 responses that result in IL-6 and MCP-1 secretion. TLR signaling in CEC did not involve NF-B (p65) activation with the inhibitory p50 form of NF-B predominating in CEC in both the healthy and inflamed colon. Development of colitis was, however, associated with the activation of MAPK family members and upregulation of MyD88-independent signaling pathways characterized by increased caspase-1 activity and IL-18 production. These findings identify changes in TLR expression and signaling during the development of colitis that may contribute to changes in the host response to bacterial antigens seen in colitis.

BACKGROUND:Active HIV infection within the central nervous system (CNS) is confined primarily to microglia. The glial cell compartment acts as a viral reservoir behind the blood-brain barrier. It provides an additional roadblock to effective pharmacological treatment via expression of multiple drug efflux transporters, including P-glycoprotein. HIV/AIDS patients frequently suffer bacterial and viral co-infections, leading to deregulation of glial cell function and release of pro-inflammatory mediators including cytokines, chemokines, and nitric oxide.METHODS:To better define the role of inflammation in decreased HIV drug accumulation into CNS targets, accumulation of the antiretroviral saquinavir was examined in purified cultures of rodent microglia exposed to the prototypical inflammatory mediator lipopolysaccharide (LPS).RESULTS:3H]-Saquinavir accumulation by microglia was rapid, and was increased up to two-fold in the presence of the specific P-glycoprotein inhibitor, PSC833. After six or 24 hours of exposure to 10 ng/ml LPS, saquinavir accumulation was decreased by up to 45%. LPS did not directly inhibit saquinavir transport, and did not affect P-glycoprotein protein expression. LPS exposure did not alter RNA and/or protein expression of other transporters including multidrug resistance-associated protein 1 and several solute carrier uptake transporters.CONCLUSIONS:The decrease in saquinavir accumulation in microglia following treatment with LPS is likely multi-factorial, since drug accumulation was attenuated by inhibitors of NF-kappabeta and the MEK1/2 pathway in the microglia cell line HAPI, and in primary microglia cultures from toll-like receptor 4 deficient mice. These data provide new pharmacological insights into why microglia act as a difficult-to-treat viral sanctuary site.

Thesis (MScMedSc)--Stellenbosch University, 2012. / Includes bibliography / ENGLISH ABSTRACT: Infection is a major cause of morbidity and mortality in infants within the first few months of life. Susceptibility to infectious disease in this vulnerable population is more prevalent in resource-limited regions, with a higher disease burden. Due to certain deficiencies in their adaptive immune system, neonates rely predominantly on their innate immune system for protection against infection, a vital component in the early host defence against pathogens. Several studies have described differences in neonatal innate toll-like receptor-mediated responses compared to adult counterparts, though very little is known about these receptor responses within resource-limited settings. To address this issue, we assessed the longitudinal development of cytokine-specific responses of TLR4 and TLR7/8 in monocytes, myeloid dendritic cells and plasmacytoid dendritic cells in infants from a resource-limited setting, South Africa, within the first 12 months of life and compared it to adults. Contrary to previously published literature, we observed heightened production of TH-1 cytokines: we showed increased responsiveness to TLR4 and TLR7/8 stimulation in infants at two and six weeks of age, which may be due to vaccination administered at birth. Unexpectedly, the hyper-inflammatory response persisted at six months in response to the LPS (TLR4) stimulus. This increased response at six months may be attributed to decreased passive immunity through infant weaning as well as increased exposure to microbial pathogens in this setting. Maturation of most cytokine responses was reached at twelve months for the TLR4 receptor, and at six months for the TLR7/8 receptor. The first year of life represents a critical period for maturation of the immune response. Data from this study point towards an elevated response within the first six months of life. This heightened response reflects both an ability to mount a sufficient TH-1 response in infancy, but more likely, the increased exposure to microbial stimuli in the environment. Thus, we speculate that these age-specific inflammatory responses may influence the outcome of immune responses to various vaccines administered, which may result in altered responsiveness to immunisation in infancy. / AFRIKAANSE OPSOMMING: Die hoof oorsaak vir morbiditeit en mortaliteit in babas binne die eerste paar maande van hul lewe word toegeskryf aan infeksie. In hulpbron beperkte gebiede, gekenmerk deur `n groter siektelas, is daar `n verhoogde vatbaarheid vir infeksie in hierdie kwesbare populasie. As gevolg van sekere gebreke in die verworwe immuunstelsel, maak pasgebore babas hoofsaaklik staat op hul aangebore immuunstelsel vir beskerming teen infeksie, ’n belangrike komponent vir die vroeë verdediging teen patogene. Verskeie studies het al die verskille in toll-tipe reseptor (TTR) bemiddelde reaksies tussen pasgebore babas en volwassenes vergelyk, maar nie veel is bekend oor hierdie reaksies in areas waar hulpbronne beperk is nie. Om hierdie kwessie aan te spreek is die longitudinale ontwikkeling van sitokien-spesifieke reaksies van die TTR4 en TTR7/8 reseptore van monosiete, miëloïede en plasmasitoïede dendritiese selle van babas in die hulpborn beperkte land Suid-Afrika, oor die eerste 12 maande geëvalueer en dit vergelyk met volwassenes. In teenstelling met vorige literatuur, het hierdie studie ’n polarisasie tot TH-1-sitokien produksie gevind: verhoogde reaktiwiteit van die TTR4 en TTR7/8 is gevind in babas van twee en ses weke oud, wat gedeeltelik as gevolg van die inenting kan wees wat toegedien was na geboorte. Hierdie hiper-inflammatoriese reaksie teen die TTR4 stimulus (Lipopolisakkaried (LPS), het teen verwagting voortgeduur tot op ses maande en kan toegeskryf word aan die vermindering van passiewe immuniteit deur spening, sowel as die toenemende blootstelling aan mikrobiese patogene in die omgewing. Maturasie vir die meerderheid van die sitokiene reaksies, is bereik op 12 maande vir TTR4, en op ses maande vir TTR7/8. Die eerste lewensjaar is ‘n kritiese periode vir die ontwikkeling van die immuunstelsel. Data van hierdie studie dui op ‘n verhoogde reaksie binne die eerste ses maande van ‘n baba se lewe. Hierdie verhoogde reaksie dui op die vermoë om `n voldoende TH-1 reaksie te ontlok, maar meer waarskynlik, verhoogde blootstelling aan mikrobiese stimuli in die omgewing. Dus spekuleer ons dat hierdie ouderdom-spesifieke reaksies dalk die uitkoms van die immuunreaksie teen verskeie entstof toediening kan beïnvloed in babas.

La polyarthrite rhumatoïde (PR) est la maladie auto-immune la plus fréquente d'une prévalence de 1%. Les cellules résidentes de la cavité synoviale, les fibroblast-like synoviocytes (FLS), sont des acteurs majeurs de la PR. Leur activation par des récepteurs de l'immunité innée participe à l'acquisition d'un phénotype agressif menant à la destruction ostéo-articulaire. Dans cette étude, nous avons évalué le rôle régulateur de miARN sur les voies de signalisation des Toll-like receptors (TLR). L'activation de TLR2 et de TLR4 dans les FLS induit la diminution de l'expression de plusieurs miARN, dont miR-19a et b (miR-19), alors que TLR2 est surexprimé. Nous avons pu ainsi montrer que miR-19 régule Tlr2 et que la transfection de mir-19 dans les FLS activés induit une diminution de l'expression de TLR2 et de la synthèse d'IL-6 et de MMP-3. Mir-19 appartient au cluster miR-17~92, dont l'expression est abaissée dans les FLS. Il code pour 6 miARN dont miR-20a. miR-20a est également sous-régulé après activation de TLR2 et TLR4 dans les FLS et les THP-1. Nous avons montré que miR-20a régule directement l'expression d'Ask1, impliquée et surexprimée après activation de TLR4. La transfection de miR-20a in vitro nous a permis de montrer que miR-20a contrôle l'expression d'ASK1 et induit une inhibition de la synthèse de cytokines majeures de la PR dans les FLS et les THP-1. Des résultats équivalents ont été obtenus ex vivo chez la souris. Ces travaux ont permis d'identifier dans les FLS rhumatoïdes des miARN anti-inflammatoires dont la baisse d'expression permet une augmentation de l'expression de TLR2 et d'ASK1. Ces miARN pourraient donc constituer de nouvelles cibles thérapeutiques.

Grâce aux nombreuses études sur le sujet, nous savons qu’une stimulation inflammatoire vasculaire excessive entraîne un débalancement des fonctions homéostatiques de l’endothélium. Ce débalancement est à l’origine d’une dysfonction endothéliale définie comme étant l’étape clé contribuant au développement de l’athérosclérose. Le Toll-like receptor-2 (TLR2) est impliqué dans l’activation cellulaire via la transcription des gènes liés à l’inflammation. Il reconnaît des molécules microbiennes mais également des facteurs endogènes non-infectieux tels que sécrétés par les tissus endommagés provenant de la dysfonction endothéliale. Ainsi, l’activation et la signalisation du TLR2 sont en étroite relation avec le développement de l’athérosclérose. Les études épidémiologiques ont confirmé le rôle athéroprotecteur de l’œstrogène via de nombreux mécanismes d’action. Ainsi, nous avons cherché à identifier de nouvelles cibles moléculaires permettant de mieux interpréter les bénéfices potentiels de l’œstrogène sur le système cardiaque. Pour la première fois chez les cellules endothéliales (CE) vasculaires de souris, nos travaux ont confirmé l’effet anti-inflammatoire de l’œstrogène via la diminution de l’expression et de l’activité du TLR2. Nous avons également déterminé l’influence de l’œstrogène sur le profil de la réponse inflammatoire de ce récepteur en mesurant les potentiels endothéliaux de migration et d’adhésion. De plus, nous avons caractérisé les voies de signalisation impliquées en démontrant l’influence négative de l’œstrogène sur la phosphorylation des kinases activées par le TLR2; illustrant l’interaction entre l’œstrogène et la signalisation de ce récepteur. Nos travaux amènent ainsi de nouvelles connaissances sur la régulation endothéliale du TLR2 et mettent en lumière les effets anti-inflammatoires et vasculaires rapides de l’œstrogène. / Evidence supports the contribution of immune responses in atherosclerosis development in part by alterations in the endothelium activation status and by the recruitment of inflammatory cells triggered by cardiovascular risk factors. These alterations are the principal cause of endothelial dysfunction defined as the key step contributing to the development of atherosclerosis. Via the transcription of genes related to inflammation, the Toll-like receptor-2 (TLR2) is involved in endothelial cell activation. It generally recognizes microbial molecules but also non-infectious endogenous factors such as those secreted by damaged tissues from the endothelial dysfunction. Thus, activation and signalization of the TLR2 are closely linked with the development of atherosclerosis. Epidemiological studies have confirmed the atheroprotective role of estrogen through multiple mechanisms of action. Thus, to better interpret the potential benefits of estrogen on the cardiovascular system, we sought to identify new molecular targets such as TLR2 regulation. For the first time in mouse vascular endothelial cells (EC), our results have confirmed the anti-inflammatory effect of estrogen via the decreased expression and activity of TLR2. We also determined the influence of estrogen on the profile of the inflammatory response triggered through this receptor by measuring endothelial migration and adhesion potentials. Furthermore, we demonstrated the interaction between estrogen and TLR2 signalling pathways with a negative influence of estrogen on the phosphorylation level of kinases activated by this receptor. Thus, our study brings new insights into the endothelial regulation of TLR2 and highlights rapid anti-inflammatory and cardioprotective effects from estrogen.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Alžbeta Horvátová Supervisor: prof. PharmDr. Petr Pávek PhD. Title of diploma thesis: Anti-inflammatory effects of ursodeoxycholyl lysophosphatidylethanolamide on THP-1 human macrophages via Toll-like receptor 4 Nonalcoholic steatohepatitis (NASH) became the most common liver disease in developed countries. It is well-known that the level of protectant phosphatidylcholine (PC) is decreased in NASH. The bile acid-phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE) was designed in order to specifically deliver PC to hepatocytes. However, previous studies have proved that UDCA-LPE possesses its proper hepatoprotectant capacity and exhibits anti-apoptotic, anti-inflammatory, anti-fibrotic properties and also improved steatosis and hyperlipidaemia in various models in vivo. These effects may be mediated secondary through modulation of immune system. Therefore, in order to dissect if UDCA-LPE directly influences immune cells in vitro, release of pro-inflammatory cytokines TNFα, IL-6 and IL-1β in LPS-induced THP-1-derived human macrophages was measured by ELISA. Moreover, effects of UDCA-LPE on MAPK signalling pathways and nuclear translocation of NFκB were...

Toll-like receptors (TLRs) are a major group of pattern recognition receptors expressed on the surface of immune cells that recognize molecular patterns associated with all classes of pathogenic microorganisms. TLR4 recognizes the lipopolysaccharide component of Gram-negative bacterial cell walls and is the only TLR known to induce signaling through both the MyD88 and TRIF pathways. Basigin, a ubiquitous cell adhesion molecule, is a member of the immunoglobulin superfamily that has the ability to influence cell signaling mediated by the MyD88 and TRIF pathways, the same signaling pathways induced by the TLR4 receptor protein. Analysis of the Basigin protein sequence indicates the presence of a hydrophilic glutamate residue within the hydrophobic transmembrane domain, but no consensus binding sites for MyD88 or TRIF. The purpose of this study was to determine if Basigin uses TLR4 for signal transduction. It is hypothesized that Basigin interacts with TLR4 and that the glutamate residue plays a role in the interaction. Enzyme-linked immunosorbent binding assays were performed using endogenous TLR4 and recombinant Basigin proteins. These analyses demonstrated that binding of Basigin to TLR4 was significantly greater than that of the control protein and that the glutamate residue in the Basigin transmembrane domain does play a role in the interaction between Basigin and TLR4 as well as many hydrophobic residues in the Basigin transmembrane domain. The data suggest that Basigin interacts with TLR4 to influence signaling cascades using MyD88 and TRIF.

A imaturidade do sistema imune adaptativo ao nascimento envolve alterações funcionais das células apresentadoras de antígenos. O objetivo foi avaliar a ativação via TLR-4 e resposta de monócitos de sangue de cordão umbilical de recém-nascidos (RN) pré-termo <34 semanas (Grupo 1), <font face=\"Symbol\">&#179;34 e <37 semanas (Grupo 2) e a termo (Grupo 3). Os resultados mostraram alta produção de IL-8, TNF-a, IL-1b e IL-6 e significativa menor produção de IL-10 por monócitos neonatais. O fator NF-kB apresentou ativação semelhante entre os neonatos e adultos. As moléculas p38, ERK-1/2 e IRAK-4 apresentaram-se mais ativadas em monócitos dos RN do Grupo 1 quando comparados aos RN do Grupo 3 e adultos. A capacidade fagocitária de monócitos e neutrófilos dos RN mostrou competência reduzida. A produção de H2O2 foi reduzida em monócitos e neutrófilos apenas dos RN pré-termo. Os resultados sugerem um perfil imunológico neonatal funcionalmente distinto, revelando um desequilíbrio da resposta imune inata, com uma menor eficiência no controle desta resposta, o que pode levar a uma predisposição à sepse. / The immaturity of the adaptive immune system at birth involves functional changes in antigen-presenting cells. The objective was to evaluate the activation via TLR-4 and response of monocytes from umbilical cord blood of preterm newborns (NB) < 34 weeks (Group 1), preterm NB <font face=\"Symbol\">&#179;34 and < 37 weeks (Group 2) and term NB (Group 3). The results show high production of IL-8, TNF-a, IL-1b and IL-6 and a significantly lower production of IL-10 by neonatal monocytes. NF-kB factor presented similar activation among neonates and adults. p38, ERK-1/2 and IRAK-4 molecules were more activated in monocytes of newborns from Group 1 as compared to newborns from Group 3 and adults. The phagocytic ability of monocytes and neutrophils from newborns showed a reduced competence. The H2O2 production was reduced in monocytes and neutrophils only in preterm newborns. The results suggest a functionally distinct neonatal immune profile, revealing an imbalance of the innate immune response, with a lower efficiency in the control of this response, which could lead to a predisposition to sepsis.

Die Infektion mit Schistosoma mansoni resultiert in einer Th2-Immunantwort mit Eosinophilie und erhöhtem IgE-Titer, wobei der wasserlösliche Extrakt der S. mansoni Eier (SEA) ausreicht um diese Reaktion auszulösen. In der vorliegenden Arbeit konnte demonstriert werden, dass sich IL-4-produzierende CD4+ T-Lymphozyten in Zellkulturen mit SEA-konditionierten Dendritischen Zellen (DCs) trotz gleichzeitig vorkommenden IFN-gamma entwickeln und SEA die Expression von Faktoren in DCs, die üblicherweise mit einer Th1-Antwort einhergehen, auf Transkriptions- und Proteinebene selektiv hemmt. Um den Faktor aus S. mansoni Eiern zu isolieren, der zur Expression von IL-4 in CD4+ Zellen und zur Inhibition von IL-12 in DCs führt, wurde eine Gelfiltrationschromatographie der exkretorisch/sekretorischen Ei-antigene (ES) durchgeführt und die Fraktionen in vitro getestet. Darin wurde gezeigt, dass Fraktionen mit einer Proteinbande von 30 kD die Expression von IL-4 in CD4+ Zellen induzieren. Dieses ES-Protein wurde durch N-terminale Sequenzierung als hepatotoxische Ribonuclease Omega-1 identifiziert, welches ebenfalls die Expression von IL-12 in DCs inhibiert und die Produktion von IL-4 in CD4+ Zellen bei einer 10-fach geringeren Proteinkonzentration als mit dem Kontrollansatz SEA induziert. Zudem sollte untersucht werden, inwieweit Toll-like Rezeptoren in der Generierung einer Th2 Antwort gegen schistosomale Antigene involviert sind. Dazu wurden TLR2-, TLR3-, TLR4- und MyD88-defiziente Mäuse mit S. mansoni infiziert und immunologische und pathologische Daten in der akuten und chronischen Phase der Infektion analysiert. Demnach sind TLR2, TLR3, TLR4 und MyD88-abhängige Signaltransduktionswege nicht für eine-Th2 Antwort notwendig, jedoch ist letzteres Molekül in der Ausprägung der typischen Leberfibrose involviert. / Infection with Schistosoma mansoni results in the induction of a Th2 immune response, eosinophilia and increased levels of IgE. The water-soluble extract of S. mansoni eggs (SEA) is sufficient to promote TH2 polarization in a dendritic cell-dependent manner. In this thesis, it was demonstrated that IL-4+ CD4+ cells emerge in cultures with SEA-conditioned dendritic cells (DCs) in the presence of IFN-gamma and that SEA inhibits selectively the expression of IL-12 and co-stimulatory markers in DCs on the transcriptional and protein level. To identify the putative protein in S. mansoni eggs mediating a Th2 induction, a gel filtration chromatography of the excretory/secretory egg antigens (ES) was conducted and the fractions tested in vitro. Fractions containing a single band of 30 kD were sufficient to promote IL-4 induction in naïve CD4+ cells. Using N-terminal sequencing this ES-protein was identified as the hepatotoxic S. mansoni ribonuclease omega-1 which displayed both biological functions observed with SEA: inhibition of IL-12 in LPS-stimulated DCs and induction of IL-4+ CD4 cells at a 10 fold lower protein concentration than SEA. In order to understand, if the innate immune receptors TLR2, TLR3, TLR4 or the TLR adaptor molecule MyD88 are involved in the generation of the Th2 response against schistosomal antigens, the respective knock out mice were infected and immunological and pathological parameters were analyzed during acute and chronic phase of infection. This study showed that during S. mansoni infection TLR2, TLR3, TLR4 and TLR activation through the MyD88-dependent pathway are neither required for the induction (priming and polarization) nor for the down-regulation of Th2 responses, however, the fibrotic response against S. mansoni eggs was significantly reduced in MyD88-deficient mice suggesting a detrimental role of this pathway in liver pathology.

La carence en donneurs de méthyle (acide folique et vitamine B12) (MDD) pendant la gestation et la lactation produit une stéato-hépatite non alcoolique (NASH) chez les animaux soumis au régime riche en graisses (HE) pendant l'âge adulte, en dépit d’une normalisation histologique et métabolique par un régime normal entre le sevrage (J21) et l’âge de puberté (J50). Le microbiote peut déclencher l'inflammation par les lipopolysaccharides (LPS) par inadaptation de l’activation de récepteur Toll-like 4(TLR4). Notre hypothèse de base est que le régime MDD, le régime HE, les LPS du microbiote et l’inflammation intestinale (modèle Dextran Sodium Sulfate (DSS) comme déclencheurs et l'immunité innée en tant que modulateur font partie d’un même scénario conduisant à la NASH. Des rats carencés (MDD), soumis ou non au régime riche en graisse à l’âge adulte (HE) et exposés ou non à deux inducteurs de l’inflammation locale et systémique, le DSS (inflammation intestinale) et les LPS (effets systémiques de l’inflammation intestinale) ont été étudiés. Nous n’observons pas d’altération de l’immunité innée (TLR4) dans les groupes MDD/DSS, MDD/HE et MDD/HE/LPS. L’inflammation observée au niveau intestinal chez les rats MDD/DSS est également observée au niveau hépatique, avec de stéatose et activation de l’inflammasome et de la chimiokine MCP-1 et IL-1beta. De façon surprenante, cet effet systémique ne met pas en jeu la voie TLR4 et son ligand LPS même quand les rats étaient exposés au LPS directement au niveau péritonéal.Notre étude permet de conclure que la NASH favorisée par les effets systémiques de l’inflammation intestinale est médiée par MCP-1/IL-1β, mais pas par l'activation de TLR4 par translocation de LPS. L’immunité innée n’ étant pas impliquée même par l’injection directe du LPS, les effets respectifs et synergiques de régime MDD, du régime HE et du LPS restent à décrypter par la suite. / Deficiency of methyl donors (folic acid and vitamin B12) (MDD) during pregnancy and lactation produces non-alcoholic steatohepatitis (NASH) in animals fed high fat (HE) diet, despite histological and metabolic normalization by a normal diet between weaning (J21) and puberty (J50). The microbiota can trigger inflammation by lipopolysaccharides (LPS) by inadaptation of Toll-like receptor activation 4 (TLR4). Our basic assumption is that MDD, HE diet, microbiota LPS and intestinal inflammation (Dextran Sodium Sulfate (DSS) model) as triggers and innate immunity as a modulator are part of the same scenario leading to NASH. Deficient rats (MDD), whether or not exposed to the high-fat diet in adulthood (HE) and whether or not exposed to two inducers of local and systemic inflammation, DSS (intestinal inflammation) or LPS (systemic effects intestinal inflammation) were studied. We did not observe alterations in innate immunity (TLR4) in the MDD/DSS, MDD/HE and MDD/HE/LPS groups. Inflammation observed in the intestines in MDD/DSS rats is also observed in the liver, with steatosis and activation of the inflammasome and chemokine MCP-1 and IL-1beta. Surprisingly, this systemic effect does not involve the TLR4 pathway and its ligand LPS even when the rats were exposed to LPS directly at the peritoneal level. Our study conclude that NASH favored by the systemic effects of Intestinal inflammation is mediated by MCP-1/IL-1β, but not by activation of TLR4 by translocation of LPS. Since innate immunity is not involved even by the direct injection of LPS, the respective and synergistic effects of MDD diet, HE diet and LPS remain to be decribed thereafter.