Type 1 diabetes (T1D) is a chronic autoimmune disease targeted against the pancreatic β-cells. Proinflammatory cytokines are considered to play a major role in the destruction of the insulin-producing β-cells. This thesis studied strategies to counteract proinflammatory cytokines in experimental T1D. Both animal models for T1D as well as β-cell preparations exposed in vitro to putative noxious conditions were examined. In the first study we observed that cytokine treatment of mouse pancreatic islets lacking inducible nitric oxide synthase (iNOS) induced a prolongation of the early stimulatory phase of glucose stimulated insulin secretion. Various experiments led to the conclusion that this prolonged stimulatory effect may involve the DAG/PLD/PKC pathway. Next, we transplanted mouse islets deficient in iNOS to spontaneously diabetic NOD mice. We observed a normalization of hyperglycemia but not a delayed allograft rejection compared to transplanted wild type islets. Thus, absence of iNOS in the graft was not sufficient to prolong allograft survival. In paper III we found that sustained glucose stimulation of rat pancreatic islets was coupled to a decreased conversion of proinsulin to insulin. Islet treatment with IL-1β was also coupled to a decreased proinsulin conversion. Islet proconvertase activity may be a target in islet damage. In paper IV prolactin (PRL) was administered to mice in the multiple low dose streptozotocin model and we observed that PRL enhanced a Th2 response. This may contribute to the protective action by PRL in this model of autoimmune T1D. Finally, by examining β-cells overexpressing Suppressor of cytokine signalling 3 (SOCS-3) it was found that this could inhibit IL-1β induced signalling through the NF-κB and MAPK pathways. SOCS-3 overexpression also inhibited apoptosis induced by cytokines in primary β-cells. Lastly, we demonstrated that SOCS-3 transgenic islets were protected in an allogeneic transplantation model.

Autoantikörper gegen Proteinase 3 (cANCA) stellen einen hochsensitiven und spezifischen Seromarker für das Krankheitsbild der Wegenersche Granulomatose dar. Während die Ätiologie dieser systemischen Vaskulitis unbekannt ist, weisen zahlreiche klinische und experimentelle Daten darauf hin, daß cANCA an der Entstehung und Chronifizierung dieser Erkrankung beteiligt sind. Insbesondere die Konsequenzen einer cANCA-Ligation an Proteinase 3 (PR3)-exprimierende Neutrophile wurden intensiv untersucht und man geht davon aus, daß Anti-PR3-Antikörper über die Aktivierung inflammatorischer, neutrophiler Zellfunktionen die Vaskulitis fördern. Über die Auswirkungen von cANCA auf Monozyten, die eine wichtige Rolle in der Regulation der Immunantwort spielen und weitere Zielzellen dieser Antikörper darstellen, ist hingegen bisher wenig bekannt. Aktivierte Monozyten sind nicht nur ein wesentlicher Bestandteil der Granulome, sondern sind auch entscheidend an den vaskulären Entzündungsinfiltraten beteiligt. Ziel der vorliegenden Studie war es daher, die Effekte von cANCA auf inflammatorische Zellfunktionen PR3-exprimierender Monozyten zu charakterisieren. Dabei war insbesondere ihr Einfluß auf die transendotheliale Migration und die Sekretion proinflammatorischer Mediatoren von Interesse. Die Isolation humaner Monozyten erfolgte mittels Gegenstromzentrifugation. Die monozytäre Transmigration wurde in mit humanen Endothelzellen bewachsenen Filtereinsätzen untersucht und mittels eines chemotaktischen Gradienten und/oder TNF-Stimulation der Endothelzellen gefördert. Die transendotheliale Migration von mit murinen, monoklonalen Anti-PR3-Antikörpern vorinkubierten Monozyten war, unabhängig vom Aktivierungszustand der Endothelzellen, deutlich vermindert. Dieser Effekt konnte sowohl durch vier von fünf cANCA-IgG-Fraktionen von Patienten mit aktiver WG als auch durch F(ab´)2-Fragmente der Autoantikörper reproduziert werden. Da bekannt ist, daß cANCA die proteolytische Aktivität von PR3 inhibieren und membrangebundenen Formen der leukozytären Serinproteasen PR3, humaner leukozytärer Elastase (HLE) und Cathepsin G (CathG) eine Rolle bei der Extravasion von Leukozyten zugesprochen wird, wurde daraufhin überprüft, ob PR3 für die monozytäre Transmigration von Bedeutung ist. Der physiologische Inhibitor dieser Serinproteasen, 1-Antitrypsin, und ein synthetischer Inhibitor von PR3 und HLE, CE-2072, verminderten die Anzahl migrierender Monozyten in gleichem Maße wie der vollständige Anti-PR3-Antikörper bzw. dessen F(ab´)2-Fragmente. Dahingegen hatte SLPI, ein Serpin, das lediglich CathG und HLE inhibiert, keinen Effekt auf die Anzahl migrierender Zellen. Dabei waren die Effekte von Anti-PR3-Antikörpern und 1-Antitrypsin nicht additiv, wodurch die Annahme, daß die Anti-PR3-mediierte Reduktion der monozytären Transmigration auf einer funktionellen Inhibition von PR3 beruht, untermauert wird. Die Reduktion der monozytären Transmigration ging nicht mit einer modifizierten endothelialen Adhäsion der Monozyten einher, wie unter dynamischen und statischen Bedingungen gezeigt werden konnte. Weder die rollende noch die feste Adhäsion der Monozyten wurde durch Anti-PR3-Antikörper oder Serinproteaseinhibitoren beeinträchtigt. Auch die durchflußzytometrisch quantifizierte Expression monozytärer ß1- und ß2-Integrine wurde durch die Autoantikörper nicht beeinflußt. Diese Ergebnisse zeigen erstmals, daß PR3 an der transendothelialen Migration, nicht aber der Adhäsion von Monozyten teilhat. Ein weiteres, wesentliches Ergebnis der vorliegenden Studie ist die, im Vergleich zu entsprechenden IgG-Kontrollen, massive Freisetzung proinflammatorischer Mediatoren aus Monozyten in Gegenwart muriner Anti-PR3-Antikörper bzw. humaner cANCA, die mittels ELISA ermittelt wurde. Die Sekretion war zeitabhängig, wobei die Sekretion von TNF- und IL-1ß der von Thromboxan A2, IL-6 und IL-8 vorausging. Im Gegensatz zu den Auswirkungen von cANCA auf die monozytäre Transmigration, konnten diese Effekte nicht durch die alleinige Ligation des Antikörpers an das Antigen PR3 reproduziert werden, sondern waren von einer simultanen Ligation der Autoantikörper an PR3 und FcR auf der monozytären Oberfläche abhängig. Eine cANCA-mediierte Retention adhärenter Monozyten im Gefäßbett bei gleichzeitiger Aktivierung der monozytären Freisetzung inflammatorischer Zytokine und Prostanoide durch cANCA, könnte nicht nur die Entstehung der extra- und perivaskulären, granulomatösen Entzündung, sondern auch die Aufrechterhaltung der nekrotisierenden Vaskulitis fördern. Insgesamt weisen die Ergebnisse dieser Studie erstmals auf eine funktionelle Rolle von PR3 bei der transendothelialen Migration von Monozyten hin. Außerdem liefern sie weitere wesentliche Hinweise darauf, wie die Interaktion von cANCA mit Monozyten an der Pathogenese der Wegenerschen Granulomatose beteiligt sein könnten.

Orientador: Iracilda Zeppone Carlos / Banca: Iracilda Zeppone Carlos / Banca: Jayro Kenupp Bastos / Banca: Angela Maria Victoriano de Campos Soares / Banca: Beatriz Marica Machado de Medeiros / Banca: Luis Carlos Spolidorio / Resumo: Produtos naturais têm contribuído intensamente para o desenvolvimento da terapêutica moderna. As plantas produzem um vasto número de substâncias, que em estado natural ou após sofrerem transformações químicas, possuem diversas atividades farmacológicas. Fungos endofíticos, organismos que vivem no interior das plantas, também podem representar novas fontes de produtos biologicamente ativos. Atualmente, a relação causal entre inflamação, imunidade inata e câncer é largamente aceita. O envolvimento de mediadores inflamatórios, como óxido nítrico (NO) e citocinas, gerados por macrófagos ativados, na patogênese das doenças inflamatórias já está bem estabelecido. Além disso, a inibição da angiogênese tem sido reconhecida como uma promissora abordagem terapêutica para o controle do crescimento tumoral, das metástases e das doenças inflamatórias crônicas. Alchornea glandulosa Poepp & Endl. (Euphorbiaceae) é uma planta com conhecida atividade antiinflamatória que está distribuída do sudeste ao sul do Brasil, principalmente na Mata Atlântica e no Cerrado. O potencial antiinflamatório, antitumoral e antiangiogênico dos compostos obtidos a partir da planta (fração acetato de etila e os compostos puros isoquercitrina, afzelina, ácido gálico, pteroginina e pteroginidina) e de fungos endofíticos presentes no interior das suas folhas (extratos acetato de etila ALG-A, ALG-02 e ALG-03) foram estudados por meio de experimentos utilizando-se culturas de macrófagos murinos, linhagens tumorais murinas de câncer de mama (LM2) e pulmão (LP07) e culturas de células endoteliais de veia umbilical humana (HUVEC). Ensaios de determinação de óxido nítrico (reagente de Griess), citocinas pró-inflamatórias TNF-α, IL-1β, IL-6 e IL-12 (ELISA), atividade citotóxica (MTT) e avaliação da taxa de inibição do crescimento de tumores tratados com injeção... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Natural products have contributed enormously to the development of important therapeutic drugs used currently in modern medicine. Plants produce a vast number of compounds that, either directly or after chemical modifications, exert pharmacological activities. Endophytic fungi, organisms which live in plants, are also being recognized as new sources of biological active substances. Nowadays, the relationship among inflammation, innate immunity and cancer are widely accepted. Inflammatory mediators as nitric oxide (NO) and cytokines produced by activated macrophages are involved in the pathogenesis of inflammatory diseases. Besides that, angiogenesis inhibition has been accepted as a promising therapy for the control of tumor growth, metastasis and also chronic inflammatory conditions. Alchornea glandulosa Poepp & Endl. (Euphorbiaceae) is a plant that demonstrates anti-inflammatory activity. It can be found in Brazil, distributed from southeast to south, mainly in the Atlantic Forest and Cerrado. The anti-inflammatory, antitumor and antiangiogenic potential of the compounds obtained from this plant (ethyl acetate fraction and the pure compounds isoquercitrin, afzelin, gallic acid, pterogynine and pterogynidine) and from the endophytic fungi present in its leaves (ALG-A, ALG-02 and ALG-03 ethyl acetate extracts) were studied using macrophage cultures, tumor cell lines (LM2 and LP07) and human umbilical vein endothelial cells (HUVEC). To evaluate anti-inflammatory and antitumor activity, in vitro assays were utilized to determine NO (Griess reagent), TNF-α, IL-1β, IL-6 and IL-12 proinflammatory cytokines (ELISA) and cytotoxicity (MTT). Tumor growth inhibition rate was also studied in vivo. Apoptosis (TUNEL assay), proliferation (bromodeoxiuridine - BrdU), invasion (double-chamber assay), capillary-like structures formation (matrigel) and NFκB activity (ELISA) were realized to study... (Complete abstract click electronic access below) / Doutor

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A glycosylated lectin (CTL) with specificity for mannose and glucose has been detected and purified from seeds of Centrolobium tomentosum, a legume plant from the Dalbergieae tribe. CTL was isolated by mannose-Sepharose affinity chromatography. The primary structure was determined by tandem mass spectrometry and consists of 245 amino acids and one N-glycosylation site, possessing high similarity with the lectin Platypodium elegans (PELa) and Pterocarpus angolensis (PAL) derived from the same tribe. Two crystal structures of CTL, with monoclinic and tetragonal forms, both complexed with methyl dimanosÃdeo has been solved at 2.25 and 1.9 Ã, respectively, with high similarity. The lectin adopts a typical canonical dimeric organization of legume lectins. The carbohydrate recognition domain (CRD), metal binding site, and glycosylation site have been characterized and the structural basis for interaction with carbohydrate been elucidated. CTL showed acute inflammatory effect in a paw edema model. The protein structure was subjected to ligand screening (dimannosides and trimannoside) by molecular docking, revealing a higher affinity for trimannosides and their interactions were compared with similar lectins, which have the same binding specificity. This is the first report of a crystal structure of a native mannose lectin / specific glucose Dalbergieae tribe with pro-inflammatory activity / Uma lectina glicosilada (CTL) com especificidade a manose e glucose foi detectada e purificada a partir de sementes de Centrolobium Tomentosum, uma leguminosa pertencente à tribo Dalbergieae. CTL foi isolada por cromatografia de afinidade de Sepharose-Manose. A estrutura primÃria foi determinada por espectrometria de massas e consiste em 245 aminoÃcidos e um sitio de ÂNÂ-glicosilaÃÃo, demonstrando similaridade com a lectina de Platypodium elegans (PELa), Pterocarpus angolensis (PAL), dentre outras, oriundas da mesma tribo. Duas estruturas cristalinas de CTL, de formas monoclÃnica e tetragonal, ambas complexadas com metil-dimanosÃdeo, foram resolvidas a 2,25 e 1,9 Ã, respectivamente, apresentando alta similaridade entre si. A lectina mostrou adotar uma organizaÃÃo dimÃrica canÃnica tÃpica de lectinas de leguminosas. O domÃnio de reconhecimento de carboidratos (CRD), local de ligaÃÃo do metal e local de glicosilaÃÃo foram caracterizados e a base estrutural para a interaÃÃo com carboidratos foi elucidado. CTL mostrou efeito inflamatÃrio agudo em um modelo de edema de pata. A estrutura da proteÃna foi submetida a uma anÃlise de interaÃÃes com dimanosÃdeos e trimanosÃdeos por Docking Molecular, revelando sua maior afinidade por trimanosÃdeos e suas interaÃÃes foram comparadas com lectinas similares que possuam a mesma especificidade de ligaÃÃo. Esse à o primeiro relato de estrutura cristalina de uma lectina nativa manose/glucose especÃfica da tribo Dalbergieae com atividade prÃ-inflamatÃria

Nos últimos anos, inúmeros avanços têm sido alcançados no que diz respeito aos mecanismos moleculares que participam na indução e manutenção da dor crônica, incluindo ativação glial. Já foi demonstrado que alguns receptores de reconhecimento padrão (PRRs), como os receptores do tipo Toll (TLRs) participam desse processo e, que em modelos de inflamação/infecção do Sistema Nervoso Central, os TLRs e os receptores do tipo NOD (NLRs) cooperam na ativação das células da glia, o que nos levou a hipotetizar que os receptores NOD1 e NOD2 também possam desempenhar um papel importante no processo de dor crônica. O NOD2 é responsável pela detecção intracelular do muramil dipeptídeo (MDP) enquanto que NOD1 reconhece o ácido diaminopimélico (iE-DAP), ambos padrões moleculares associados a patógenos (PAMPs) encontrados no peptideoglicano de bactérias. Após o reconhecimento, NLRs recrutam diretamente RIPK2 (proteína 2 de interação com o receptor RICK), uma serina-treonina quinase importante na ativação do fator nuclear kB (NF-kB). Assim, o objetivo do presente estudo foi avaliar a participação de NOD1 e NOD2, via RIPK2, no desenvolvimento da hipersensibilidade mecânica neuropática focando principalmente nos mecanismos espinais envolvidos. Dessa maneira, foi observado que os animais NOD1-/-, NOD2-/- e RIPK2-/- apresentaram redução significativa da hipersensibilidade nociceptiva mecânica quando comparado aos animais selvagens após indução de neuropatia periférica pelo modelo experimental de lesão limitada do nervo isquiático (SNI, Spared Nerve Injury). Ao contrário, a hipersensibilidade inflamatória induzida pelo adjuvante completo de Freud (CFA) não foi reduzida nesses animais. A redução da dor neuropática em NOD1-/-, NOD2-/- e RIPK2-/- foi associada a uma diminuição da expressão de IBA-1, GFAP, IL-1, TNF- e P2X4 na medula espinal quando comparado ao grupo WT. In vitro, foi observado que culturas primárias de micróglia não induziram liberação de IL-1, TNF-, IL-6 em resposta ao MDP (10g/mL) e iE-DAP (100ng/mL). No entanto, quando o MDP foi administrado juntamente com uma baixa concentração de lipopolissacarídeo (LPS) (0,1ng/mL), apresentou uma forte produção destas citocinas. Além disso, também foi demonstrado que células periféricas que infiltram na medula espinal podem expressar NOD1 e NOD2 e portanto serem capazes de induzir hipersensibilidade mecânica e ativação microglial após a indução de neuropatia. Dessa maneira, os resultados sugerem que NOD1 e NOD2, via RIPK2, contribuem para a gênese da dor neuropática, possivelmente mediando a liberação de citocinas pró-nociceptivas e a ativação de células gliais. Além disso, os resultados apontam ação potencial de NOD2 com TLR4 no intuito de estimular a ativação glial. Estes mecanismos representam uma nova abordagem para elucidar os mecanismos envolvidos na fisiopatologia da dor crônica e um possível alvo para o desenvolvimento de drogas para o tratamento da dor neuropática. / In the last years, many advances have been made related to the molecular mechanisms involved in the induction and maintenance of chronic pain, including glial activation. It has been shown that some pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) are involved in this process, and that in inflammation/infection models of the CNS, the TLRs and Nod-like receptors (NLRs) cooperate in activation of glial cells, which led us to hypothesize that NOD1 and NOD2 receptors may also play an important role in chronic pain process. NOD2 are responsible by intracellular detection of muramyl dipeptide (MDP) and NOD1 detects meso-diaminopimelic acid (iE-DAP), pathogen-associated molecular patterns (PAMPs) found in the peptidoglycan from bacteria. Upon recognition, NLRs recruit directly RIPK2, an adaptor protein, important in NLRs-mediated NFB activation. In the present study, we aimed to evaluate the participation of NOD1 and NOD2, via RIPK2, in the development of neuropathic mechanical hypersensitivity focusing mainly on spinal mechanisms involved. The results demonstrate that NOD1-/-, NOD2-/-, RIPK2-/- showed a significant reduction in mechanical hypersensitivity when compared to WT mice, after submitted to an experimental model of neuropathic pain Spared Nerve Injury (SNI). Interestingly, CFA-induced chronic inflammatory hypersensitivity was not decreased in these mice. The reduction in neuropathic pain in NOD1-/-, NOD2-/- and RIPK2-/- mice was associated with a decrease in the expression of IBA-1, GFAP, IL-1, TNF- and P2X4 in spinal cord when compared with WT. In vitro, it was observed that primary cultures of microglia did not produce IL-1, TNF-, IL-6 in response to MDP (3g/mL) or iE-DAP (100ng/mL). However, MDP, together with an ineffective concentration of LPS (0.1ng/mL), produced a robust production of these cytokines. Moreover, it was also demonstrated that peripheral cells infiltrating the spinal cord could express NOD1 and NOD2 and thus, be able to induce mechanical hypersensitivity and microglial activation after induction of peripheral neuropathy. The results suggest that NOD1 and NOD2, via RIPK2, contribute to the genesis of neuropathic pain, possibly by mediating the release of pronociceptive cytokines and increased glial cells activation. Moreover, the results indicate potential action of NOD2 with TLR4 in attempt to stimulate glial cells activation. These mechanisms represent a novel approach for elucidating the pathophysiology of chronic pain, and a target for the development of drugs for the treatment of neuropathic pain.

No description available.

! BACKGROUND: Exposure to Environmental Tobacco Smoke (ETS) is elevating blood levels of inflammatory mediators and chemoattractants which seem to play an important role in the development of several diseases (e.g. Chronic Obstructive Pulmonary Disease). First evidences showed that men and women might differ in their proneness for these diseases. The aim of this study was to investigate whether there are effects of ETS during pregnancy on inflammatory cytokines in cord blood and in mother’s blood and if there are any differences between male and female newborns. METHODS: Within the LiNA (Lifestyle and environmental factors and their influence on Newborn Allergy Risk) study, whole blood samples of 460 mother-child pairs were analyzed for the concentrations of IL-6, IL-8, IL-10, IL-12, IL-4, IL-5, INF-gamma, TNF-alpha and MCP-1 using cytrometic bead asseys. The association between ETS exposure and cytokines was calculated using the Mann-Whitney-U-test and adjusted with a multiple regression model for parental atopy, parental education status and cat ownership. The exposure assessment is based on questionnaire data on smoking behaviour of the parents and measurement of indoor benzene concentration. RESULTS: Female newborn, being exposed in utero to 10 cigarettes a day or more, had significantly higher blood concentrations of IL-8, IL-6 and MCP-1 whereas there have been no elevations in male newborn being exposed to the same amount of cigarettes. Furthermore a significantly decreased amount of INF-gamma was found in cord blood of male newborns but not in female newborns. General increasing levels of TNF-alpha in cord blood where found for daily smoke exposure without relating it to the exact number of cigarettes. CONCLUSION: The data of this study refer to gender-specific differences in the susceptibility to ETS exposure. The induction of inflammatory signals in cord blood in response to cigarette smoke exposure is stronger in female than in male newborn. / Die vorliegende Arbeit ist Teil einer umweltepidemiologischen Kohortenstudie (LiNA), in der der Einfluss von Umwelt- und Lebensbedingungen auf die Entwicklung von Immunsystem und Allergien bei Neugeborenen unter Einbezug der vorgeburtlichen Zeit untersucht wird. In welchem Maße sich eine Rauchbelastung während der Schwangerschaft auf die Zytokinmuster der Neugeborenen im Nabelschnurblut auswirkt und inwiefern dies mit dem Zytokinmuster der Mutter korreliert, sollte das Ziel dieser Dissertation sein. Dafür wurden Daten von insgesamt 629 Mutter-Kind-Paaren erhoben, Zytokin- und Chemokinbestimmungen, sowie die des Gesamt-IgE aus den Blutproben der 34. SSW und denen der Nabelschnur vorgenommen. Interessanterweise konnten geschlechterspezifische Unterschiede im Zytokinspektrum der Neugeborenen gefunden werden. Bei den weiblichen Neugeborenen zeigte sich eine deutliche Erhöhung proinflammatorischer Marker, wenn deren Mütter dem Rauch von mehr als 10 Zigaretten pro Tag ausgesetzt waren. Dieser Anstieg war weder im Blut der männlichen Neugeborenen noch im Blut der Schwangeren in der 34. SSW zu beobachten. Zusätzlich konnte beobachtet werden, dass auch einzig die männlichen Neugeborenen stark negativ mit ihrer IFN-gamma-Produktion auf die passive Rauchbelastung reagieren. Die mit dieser Arbeit ermittelten Daten, dass das Immunsystem beim Neugeborenen geschlechterspezifisch unterschiedlich auf Tabakrauch zu reagieren scheint, sind erstmals in der Literatur zu finden. Die Erforschung des Immunsystems und dessen Beteiligung an zahlreichen Erkrankungen, besonders den chronisch Inflammatorischen, ist durchaus relevant im medizinischen Alltag. Diese Arbeit trägt einen weiteren Baustein dazu bei und gibt Anstoß für weitere Studien.

No description available.

Increasing evidence implicates the presence of bacteria in intrauterine tissues as an important risk factor for spontaneous preterm labor. Epigenetic alterations of innate immunity genes may increase the mother’s sensitivity to subclinical levels of bacteria. This study examined the presence of TET2, TLR-2, and TLR-9 in intrauterine tissue, and evaluated whether epigenetic alterations of these genes, as well as IL-8, changed their expression in human decidual tissue and a macrophage cell culture. Immunohistochemicalstaining was used to detect the presence of these proteins in intrauterine tissue. Gene expression changes were evaluated in stimulated monocytes and macrophages. Fluorescence immunohistochemistry was used to track translocation of TET2 in stimulated monocytes and macrophages. Secreted IL-8 concentration was detected with ELISA. Decidual expression of TET2, TLR-2, and TLR-9 increased in the order TNL < TL < sPTL < iPTL. This study found that TET2, TLR-2, TLR-9, and IL-8 are regulated by epigenetic mechanisms. This study was the first to report activation of TET2 involves its translocation from the cytosol to the nucleus in macrophages.

Les glucocorticoïdes sont les médicaments les plus efficaces pour le contrôle de l'obstruction respiratoire chez les chevaux atteints du souffle, et de l'asthme humain. Toutefois, les neutrophiles persistent dans les voies respiratoires suite à ce traitement. Nous avons précédemment rapporté que les neutrophiles sanguins humains et équins sont sensibles à l'action des glucocorticoïdes. Comme elle contribue à l'insensibilité des cellules épithéliales pulmonaires humaines aux glucocorticoïdes, nous avons émis l'hypothèse que l'IL-17 a un effet similaire sur les neutrophiles et qu’elle contribue à leur persistance dans les voies respiratoires asthmatiques. Objectifs : Évaluer 1. L’expression des deux sous-unités du récepteur de l’IL-17 (l'IL-17RA/IL-17RC) chez les neutrophiles équins hautement purifiés. 2. Si l'IL-17 active directement les neutrophiles et si cette réponse est sensible à l'action des glucocorticoïdes. 3. L'effet de l'IL-17 sur la viabilité et l'apoptose des neutrophiles. Résultats: 1. Les neutrophiles expriment l’IL-17RA/IL-17RC aux niveaux translationnel et protéique. 2. L’IL-17 induit une activation sélective des neutrophiles (surrégulation de l’IL-8), qui n’est pas atténuée par dexaméthasone et 3. l’IL-17 augmente la viabilité des neutrophiles stimulés (LPS) par une diminution de l'apoptose. Nos résultats indiquent que l'IL-17 active directement le neutrophile équin, et que l’augmentation de l’IL-8 (puissant chimioatractant des neutrophiles) qui en résulte n’est pas contrôlée par la dexaméthasone. L'IL-17 pourrait aussi contribuer à la persistance de neutrophiles dans les voies respiratoires chez les chevaux atteints du souffle, en diminuant l'apoptose. / Glucocorticoids are the most potent drugs for the control of the airway obstruction present in heaves and asthma, although the airway neutrophilia persist with these agents. It was previously reported that human and equine’s peripheral blood neutrophils are sensitive to glucocorticoid. Interleukin-17 (IL-17) is a cytokine contributing to glucocorticoid insensitivity airway epithelial cells in human. We therefore hypothesized that IL-17 has a similar effect on neutrophils and contributes to the persistence of these cells in the airways in response to glucocorticoid therapy. In this study, we evaluated: 1. The expression of both subunits of IL-17 receptor (IL-17RA/ IL-17RC) in highly purified neutrophils. 2. The gene expression of proinflammatory cytokines in neutrophils to assess their activation by IL-17 and their effect in these cells treated with glucocorticoids. 3. The effects of IL-17 on the viability and apoptosis in neutrophils were performed. Results showed that 1. Equine neutrophils express IL-17RA and IL-17RC at transcriptional at protein level. 2. IL-17 induces a selective activation in neutrophils, which results in an upregulation of IL-8, not attenuated by dexamethasone and finally, 3. IL-17 increases the viability of neutrophils stimulated with LPS by a decrease in apoptosis. Our results indicate that IL-17 directly activates neutrophils to upregulate IL-8, a potent neutrophils chemoattractant, and that this response is not prevented by glucocorticoids. They also suggest a possible role of IL-17 in the persistence of neutrophils in the asthmatic airways by decreasing apoptosis.