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INTRODUCTION: Specialized pro-resolving lipid mediators (SPM) such as resolvin-D1 (RvD1) act to resolve vascular inflammation and may guard against the progression of restenosis following cardiovascular interventions. Stimulating synthesis of these mediators directly in vascular cells may increase their local availability, and thus, protect against restenotic injury. However, the ability of endothelial (EC) and vascular smooth muscle cells (VSMC) to produce SPMs from their polyunsaturated fatty acid precursor decosahexaenoic acid (DHA) via lipoxygenase (LO) enzymatic transformation remains unknown. We sought to determine whether vascular cells produce SPMs from DHA and, if they do, how inflammation and mechanical injury of the vasculature alter biosynthesis. METHODS: Primary cultures of human saphenous vein endothelial and smooth muscle cells were treated with DHA in cell culture media (+ 10% serum) for 4h-24h. Freshly dissected rabbit aorta was incubated intact or following gentle endothelial denudation in cell culture media (+10% serum) with or without DHA for 48h. SPM levels in media were quantified by LC-MS/MS and ELISA and lipoxygenase expression and localization were assessed by western blotting and immunofluorescence staining, respectively. RESULTS: EC and SMC receiving media without DHA did not synthesize SPMs within the detection limits of the assay, whereas DHA treatment produced 17-HDHA, 14-HDHA, Mar1, RvD5, RvD2, and a dose and time-dependent increase in RvD1 production in EC (10.1 ±1.0 pg for 1000nM at 24h) and SMC (7.4 ± 0.2 pg for 1000nM at 24h). Intact rabbit aorta incubated in DHA+ media produced 0.24 ± 0.05 pg RvD1/mg tissue whereas aorta incubated in DHA− media produced 0.13 ± 0.007 pg RvD1/mg tissue. Moreover, EC-denuded aortas produced less RvD1/mg tissue than intact aortas. 5-LO was expressed in both cell types, however DHA induced 5-LO expression in EC (1.3 fold -DHA) but not in SMC. DHA promoted a nuclear to cytoplasmic shift of 5-LO in both EC and SMC. Finally, TNF-α stimulated an increase in RvD1 production in EC. CONCLUSIONS: Human vascular cells and rabbit vascular tissue can biosynthesize SPMs de novo from their precursor DHA, signifying a new source of SPMs in the vasculature.

Carboxylesterases (CEs) are nonspecific hydrolytic enzymes and responsible for the metabolism of xenobiotics and endobiotics that contain ester bonds. There are two human CE isoforms found in liver, CES1 and CES2. In this study it is shown that the mere abundance of CES1 protein expression in human liver does not predict its biochemical activity. The human interindividual variation in CES1 activities may attribute to several mechanisms. One possibility is the presence of endogenous inhibitors in liver, arachidonic acid (AA) and 27-hydroxycholesterol (27-HC). CES1 is also expressed in human monocytes/macrophages and is proposed to catalyze the rate-limiting step of cholesterol ester mobilization in macrophages. It is of interest to determine whether CES1 can degrade the lipid mediators, 2-arachidonoylglycerol (2-AG), prostaglandin E2-1-glyceryl ester (PGE2-G), and prostaglandin F2α-1-glyceryl ester (PGF2α-G), in monocytes/macrophages and to determine if this metabolism is inhibited by organophosphate pesticide exposure.

Rheumatoid arthritis (RA) is a chronic disease characterized by cycles of inflammation and resolution. Previously, it was believed that the resolution of inflammation is simply dissipation of pro-inflammatory signals, although current research indicates that resolution is an active process. Acute inflammation follows defined phases of induction, inflammation and resolution, and resolution occurs by an active process that requires COX-2 activity. This study aims to address whether this paradigm extends to a recognized model of chronic inflammation. We demonstrated in murine collageninduced arthritis that chronic inflammation follows the same sequential course. While there is the normal production of pro-inflammatory cytokines during inflammation and anti-inflammatory mediators such as 15-deoxyΔ12,14PGJ2 (15d-PGJ2) during resolution, interestingly there is sustained production of both COX-2 and the presumably proinflammatory PGE2 during both phases. Blocking COX-2 activity and therefore production of PGE2 during the resolution phase perpetuated instead of attenuated inflammation. Repletion with PGE2 analogs restored homeostasis, and this function is mediated by the pro-resolving lipoxygenase metabolite, lipoxin A4 (LXA4), which is a potent stop signal. Thus, the study provided in vivo evidence for a natural, endogenous link between the cyclooxygenase-lipoxygenase pathways and showed that PGE2 serves as a feedback inhibitor essential for limiting chronic inflammation in autoimmune arthritis. These findings may explain the enigma regarding why COX-2 inhibitors are palliative rather than curative in humans because blocking resolution may mitigate the benefit of preventing induction. / Microbiology and Immunology

No / Because of confounding factors, the effects of dietary n-3 polyunsaturated fatty acids (PUFA) on type 1 diabetes remain to be clarified. We therefore evaluated whether fat-1 transgenic mice, a well-controlled experimental model endogenously synthesizing n-3 PUFA, were protected against streptozotocin (STZ)-induced diabetes. We then aimed to elucidate the in vivo response at the pancreatic level. Beta-Cell destruction was produced by multiple low-doses STZ (MLD-STZ). Blood glucose level, plasma insulin level, and plasma lipid analysis were then performed. Pancreatic mRNA expression of cytokines, the monocyte chemoattractant protein, and GLUT2 were evaluated as well as pancreas nuclear factor (NF)-kB p65 and inhibitor of kB (IkB) protein expression. Insulin and cleaved caspase-3 immunostaining and lipidomic analysis were performed in the pancreas. STZ-induced fat-1 mice did not develop hyperglycemia compared with wild-type mice, and Beta-cell destruction was prevented as evidenced by lack of histological pancreatic damage or reduced insulin level. The prevention of Beta-cell destruction was associated with no proinflammatory cytokine induction (tumor necrosis factor-alpha, interleukin-1Beta, inducible nitric oxide synthase) in the pancreas, a decreased NF-kB, and increased IkB pancreatic protein expression. In the fat-1-treated mice, proinflammatory arachidonic-derived mediators as prostaglandin E2 and 12-hydroxyeicosatetraenoic acid were decreased and the anti-inflammatory lipoxin A4 was detected. Moreover, the 18-hydroxyeicosapentaenoic acid, precursor of the anti-inflammatory resolvin E1, was highly increased. Collectively, these findings indicate that fat-1 mice were protected against MLD-STZ-induced diabetes and pointed out for the first time in vivo the beneficial effects of n-3 PUFA at the pancreatic level, on each step of the development of the pathology-inflammation, Beta-cell damage-through cytokine response and lipid mediator production.

Achromobacter xylosoxidans (A. xylosoxidans) é um bacilo gram negativo, aeróbio, móvel, não fermentador de glicose e oxidase positivo, que coloniza habitualmente o trato digestivo e auditivo de humanos. Este bacilo tem sido associado a infecções oportunistas graves, especialmente pneumonia, em indivíduos imunossuprimidos, que em geral, são de difícil controle devido principalmente a fatores de virulência, mecanismos de escape e mutirresistência a antibióticoterapia. Dentre as condições que predispõem o desenvolvimento de infecção pulmonar por A. xylosoxidans, o câncer, a fibrose cística (FC) e a doença pulmonar obstrutiva crônica (DPOC) são as mais comuns. Essas doenças apresentam produção aumentada de vários mediadores lipídicos, como LTB4 e PGE2. A PGE2 é um lipídeo imunossupressor atuante no sistema imune inato e adaptativo que regula, por exemplo, a liberação de citocinas e quimiocinas, a ativação de células T, além de inibir as funções efetoras dos macrófagos. O LTB4, por outro lado, está associado ao recrutamento de células para o foco infeccioso, a ativação dos mecanismos efetores dos macrófagos, e aumento de mediadores inflamatórios. Neste trabalho, nosso objetivo foi investigar se, esses mediadores são liberados durante a infecção pulmonar por A. xylosoxidans e o possível papel dos mesmos. Nossos resultados demonstram que os tratamentos com celecoxibe, inibidor da síntese de prostaglandinas (PGs), nas doses de 1mg/kg ou 5mg/kg, não alteram a sobrevida dos animais infectados com inóculo letal ou subletal de A. xylosoxidans. No entanto, o tratamento com MK886, um inibidor da produção de leucotrienos (LTs), resultou em aumento da mortalidade dos animais infectados com inóculos letal ou subletal, redução do recrutamento de neutrófilos no dia 1 após infecção, redução de IL-6 do dia 14 e aumento de TNF-, IL-1 e MIP-1 no dia 7, KC no dia 14 e PGE2, em todos os períodos estudados. Este tratamento também induziu no lavado broncoalveolar, a diminuição não significativa do extravasamento de proteínas no dia 1, mas aumento significativo no dia 3. Com base nesses dados, podemos sugerimos que o tratamento com MK886 aumenta a mortalidade dos animais, devido ao aumento da permeabilidade vascular, com consequente edema, que leva os animais a insuficiência respiratória. Outros experimentos serão realizados para determinar o papel das prostaglandinas (PGs) e/ou metabolitos do ácido araquidônico neste fenômeno. / Achromobacter xylosoxidans (A. xylosoxidans) is a gram negative bacilli, aerobic, mobile, glucose non fermenter and oxidase positive, which normally colonizes the digestive and auditory tract of humans. This bacillus has been associated with severe opportunistic infections, especially pneumonia, in immunocompromised individuals, which are generally difficult to control mainly due to virulence factors, mechanisms and exhaust multidrug resistance to antibiotic therapy. Among the conditions that predispose the development of pulmonary infection by A. xylosoxidans, cancer, cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) are the most common. These diseases have increased production of various lipid mediators, such as LTB4 and PGE2. PGE2 is an immunosuppressive lipid active in the innate and adaptive immune system that regulates, for example, the release of cytokines and chemokines, activation of T cells and inhibits the effector functions of macrophages. LTB4, on the other hand, is associated with the recruitment of cells to the infection, and the activation of effector mechanisms of macrophages, and increased production of inflammatory mediators. In this study, our aim was to investigate whether these mediators are released during pulmonary infection by A. xylosoxidans and the possible role of the same. Our results demonstrate that treatment with celecoxib, prostaglandin synthesis inhibitor (PGs), at doses of 1mg/kg or 5mg/kg not alter the survival of animals infected with lethal or sublethal inoculum of A. xylosoxidans. However, treatment with MK886, an inhibitor of the production of leukotrienes (LTs) resulted in an increased mortality of the animals infected with lethal or sublethal inoculum, reduce the recruitment of neutrophils on day 1 after infection, reduction in IL-6 day 14 and increased TNF-, IL-1 and MIP-1 at day 7, KC in day 14 and PGE2 in all periods. This treatment also induced in the bronchoalveolar lavage, no significant decrease protein extravasation in the day 1, but significantly increased on day 3. Based on these data, we suggest that treatment with MK886 increases the mortality of animals due to increased vascular permeability, with consequent edema, which leads the animals to respiratory failure. Other experiments will be conducted to determine the role of prostaglandins (PGs) and/or metabolites of arachidonic acid in this phenomenon.

Leucotrienos e prostaglandinas são metabólitos do ácido araquidônico que, além de mediadores da inflamação são importantes imunomoduladores da liberação de citocinas, nas respostas imune inata e adquirida. Embora estes mediadores apresentem potencial para serem utilizados como adjuvantes ou imunomoduladores da resposta imune, eles são altamente instáveis, dificultando o uso in vivo. Por esta razão, estas substâncias foram incorporadas em um sistema polimérico microestruturado. Este foi constituído de microesferas de quatro a seis micrômetros de diâmetro, contendo leucotrieno B4 (LTB4) ou prostaglandina E2 (PGE2) incorporados na matriz polimérica (PLGA). A caracterização in vitro das microesferas de PLGA, contendo LTB4 ou PGE2, foi feita através da determinação da morfologia e medida dos diâmetros médios, taxa de encapsulação e perfil de liberação in vitro dos mediadores. Além disso, foi avaliada a preservação da atividade biológica do LTB4 liberado das microesferas, através do efeito do mesmo sobre a expressão de moléculas de adesão Mac-1 por citometria de fluxo. Também foram avaliadas a preservação da atividade biológica do LTB4 e da PGE2 liberados do interior das microesferas, através de estudos com microscopia intravital e a ativação de células endoteliais humanas (HUVECs e HUAECs). Realizamos ainda, ensaio de fagocitose com as microesferas contendo os dois mediadores encapsulados, utilizando macrófagos peritoneais murinos, além da avaliação da sobrevivência dos animais tratados intranasalmente com microesferas contendo LTB4 ou PGE2 durante a infecção pelo H. capulatum. Nestes animais, avaliamos a reação inflamatória pulmonar, o número de UFCs recuperadas dos pulmões e a modulação da resposta imune, através da quantificação de citocinas inflamatórias. Os estudos abordados neste trabalho revelaram achados interessantes e importantes quanto ao uso de microesferas biodegradáveis contendo mediadores lipídicos em situação de terapia, especialmente quando estes estão envolvidos em processos inflamatórios e/ou infecciosos. / Leukotrienes and prostaglandins are arachidonic acid metabolites, which participate in the inflammatory response and modulate cytokines release in both adaptive and innate immune responses. However, some physicochemical characteristics of these mediators, such as poor solubility in water and chemical instability, make them difficult to administer in vivo. In this sudy, we developed a polymeric microparticulate system for the encapsulation of lipid mediators. Regarding the in vitro characterization of the microspheres, we determined their diameters, evaluated the in vitro release of the mediators and the microspheres uptake by peritoneal macrophages. To assess the preservation of the biological activities of these mediators, we conducted intravital microscopy studies and determined the effect of LTB4 and PGE2-loaded biodegradable microspheres on inflammatory mediators release by murine peritoneal macrophages and human endothelial cells. In mice infected by H. capsulatum, we investigated the effects of intranasal administration of the microspheres on pulmonary inflammatory response. In this context, we analyzed the inflammatory cells recruited to the bronchoalveolar space, the mice survival and the number of CFUs recovered from the lungs after the administrations. We also assessed the cytokines release by the lung cells after the treatment with microspheres during the course of the infection. In conclusion, our findings showed that biodegradable microspheres could preserve the biological activity of the encapsulated mediators indicating their use as a new strategy to modulate cell activation, especially in the innate immune response.

A tuberculose é responsável por mais de 2 milhões de mortes ao ano. A imunidade protetora contra a tuberculose está relacionada com a ativação de linfócitos CD4+ e CD8+ produtores de IFN-g, citocina que potencializa os mecanismos microbicidas dos macrófagos para eliminação dos bacilos. Nos últimos anos, o leucotrieno B4 (LTB4) destacou-se como mediador lipídico que participa da imunidade protetora contra diversas infecções, incluindo a tuberculose. Dessa forma, o objetivo desse estudo foi avaliar o papel dos leucotrienos na proteção induzida pela imunização homóloga com DNA-HSP65 ou heteróloga com BCG/DNA-HSP65. Para isso, inicialmente, nós confirmamos a participação dos leucotrienos no controle da infecção por M. tuberculosis ao mostrar que animais C57BL/6, que controlam a replicação dos bacilos, secretam mais LTB4; e ao bloquear a síntese de leucotrienos com a droga MK-886, estes animais ficaram suscetíveis à infecção. Em seguida, nós passamos a avaliar se os leucotrienos participavam da proteção conferida pela imunização homóloga com DNA-HSP65 ou heteróloga (prime-boost) com BCG/DNA-HSP65. Nossos resultados mostraram que animais deficientes para a síntese de LT (5-LO KO) infectados foram mais suscetíveis à infecção em relação aos animais WT. A maior suscetibilidade dos animais 5-LO KO foi associada à redução na secreção de IFN-g, nitrito e IL-17, aumento na secreção de PGE2, defeitos no recrutamento de células inflamatórias e aumento no influxo de células Foxp3+ para os pulmões. A imunização homóloga perdeu completamente seu efeito protetor na ausência de leucotrienos, enquanto a imunização heteróloga induziu proteção parcial. Animais 5-LO KO imunizados pelo esquema prime-boost secretaram concentrações mais elevadas de IL-17 e tiveram menor influxo de células Foxp3+ para os pulmões quando comparados aos animais 5-LO KO não imunizados e infectados. A inibição da síntese de prostaglandinas durante o protocolo de imunização pela estratégia prime-boost reduziu a capacidade protetora da vacina tanto em animais WT como nos 5-LO KO, sugerindo que as prostaglandinas podem desempenhar papel no processo de imunização. Em conjunto, nossos resultados reforçam a importância dos leucotrienos na imunidade protetora contra tuberculose, sugerindo sua atuação indireta, uma vez que, além de contribuírem para síntese de IFN-g e nitrito, também parecem colaborar na síntese de IL-17. / Tuberculosis is responsible for more than 2 millions of death for year. The immune response against tuberculosis is related to activation of IFN-g-producing CD4+ and CD8+ cells. IFN-g increases the microbicidal mechanisms of macrophages to kill intracellular bacilli. Recently, the lipid mediator leukotriene B4 (LTB4) has been related to protection against several diseases, including tuberculosis. In this sense, the aim of this study was to evaluate the role of leukotrienes in the protection induced by homologous immunization with DNA-HSP65 or heterologous with BCG/DNA-HSP65 (prime-boost). Firstly, we confirmed the role of leukotrienes to control the replication of M. tuberculosis when we showed that C57BL/6 mice, which are able to contain bacilli growth, secreted high levels of LTB4; and when we blocked leukotrienes synthesis by treatment with MK-886, C57BL/6 mice became more susceptible to infection. Then, we evaluated the role of leukotrienes in the protection induced by homologous or heterologous (prime-boost) immunization. Our data showed that animals deficient in leukotrienes synthesis (5-LO KO) infected with M. tuberculosis were more susceptible to infection than WT mice. The higher susceptibility of 5-LO KO was related to the decreasing of IFN-g, nitrite and IL-17 production, increasing of PGE2 secretion, defective recruitment of inflammatory cells and increased influx of Foxp3+ cells to the lungs. Homologous immunization has lost completely its protector effect in the absence of leukotrienes, while heterologous immunization induced only partial protection. Prime-boost-immunized 5-LO KO mice secreted higher levels of IL-17 and had lower influx of Foxp3+ cells to the lungs, when compared to non-immunized infected 5-LO KO. The abrogation of the synthesis of prostaglandins during the immunization by prime-boost reduced the protector effect of the vaccine either in WT and 5-LO KO mice, suggesting that prostaglandins may be important to the process of immunization. Together, our data reinforce the key role of leukotrines in immune response against tuberculosis, suggesting that these lipid mediators may act indirectly to induce IFN-g, nitrite and IL-17 synthesis.

Leucotrienos e prostaglandinas são metabólitos do ácido araquidônico que, além de mediadores da inflamação são importantes imunomoduladores da liberação de citocinas, nas respostas imune inata e adquirida. Embora estes mediadores apresentem potencial para serem utilizados como adjuvantes ou imunomoduladores da resposta imune, eles são altamente instáveis, dificultando o uso in vivo. Por esta razão, estas substâncias foram incorporadas em um sistema polimérico microestruturado. Este foi constituído de microesferas de quatro a seis micrômetros de diâmetro, contendo leucotrieno B4 (LTB4) ou prostaglandina E2 (PGE2) incorporados na matriz polimérica (PLGA). A caracterização in vitro das microesferas de PLGA, contendo LTB4 ou PGE2, foi feita através da determinação da morfologia e medida dos diâmetros médios, taxa de encapsulação e perfil de liberação in vitro dos mediadores. Além disso, foi avaliada a preservação da atividade biológica do LTB4 liberado das microesferas, através do efeito do mesmo sobre a expressão de moléculas de adesão Mac-1 por citometria de fluxo. Também foram avaliadas a preservação da atividade biológica do LTB4 e da PGE2 liberados do interior das microesferas, através de estudos com microscopia intravital e a ativação de células endoteliais humanas (HUVECs e HUAECs). Realizamos ainda, ensaio de fagocitose com as microesferas contendo os dois mediadores encapsulados, utilizando macrófagos peritoneais murinos, além da avaliação da sobrevivência dos animais tratados intranasalmente com microesferas contendo LTB4 ou PGE2 durante a infecção pelo H. capulatum. Nestes animais, avaliamos a reação inflamatória pulmonar, o número de UFCs recuperadas dos pulmões e a modulação da resposta imune, através da quantificação de citocinas inflamatórias. Os estudos abordados neste trabalho revelaram achados interessantes e importantes quanto ao uso de microesferas biodegradáveis contendo mediadores lipídicos em situação de terapia, especialmente quando estes estão envolvidos em processos inflamatórios e/ou infecciosos. / Leukotrienes and prostaglandins are arachidonic acid metabolites, which participate in the inflammatory response and modulate cytokines release in both adaptive and innate immune responses. However, some physicochemical characteristics of these mediators, such as poor solubility in water and chemical instability, make them difficult to administer in vivo. In this sudy, we developed a polymeric microparticulate system for the encapsulation of lipid mediators. Regarding the in vitro characterization of the microspheres, we determined their diameters, evaluated the in vitro release of the mediators and the microspheres uptake by peritoneal macrophages. To assess the preservation of the biological activities of these mediators, we conducted intravital microscopy studies and determined the effect of LTB4 and PGE2-loaded biodegradable microspheres on inflammatory mediators release by murine peritoneal macrophages and human endothelial cells. In mice infected by H. capsulatum, we investigated the effects of intranasal administration of the microspheres on pulmonary inflammatory response. In this context, we analyzed the inflammatory cells recruited to the bronchoalveolar space, the mice survival and the number of CFUs recovered from the lungs after the administrations. We also assessed the cytokines release by the lung cells after the treatment with microspheres during the course of the infection. In conclusion, our findings showed that biodegradable microspheres could preserve the biological activity of the encapsulated mediators indicating their use as a new strategy to modulate cell activation, especially in the innate immune response.

Achromobacter xylosoxidans (A. xylosoxidans) é um bacilo gram negativo, aeróbio, móvel, não fermentador de glicose e oxidase positivo, que coloniza habitualmente o trato digestivo e auditivo de humanos. Este bacilo tem sido associado a infecções oportunistas graves, especialmente pneumonia, em indivíduos imunossuprimidos, que em geral, são de difícil controle devido principalmente a fatores de virulência, mecanismos de escape e mutirresistência a antibióticoterapia. Dentre as condições que predispõem o desenvolvimento de infecção pulmonar por A. xylosoxidans, o câncer, a fibrose cística (FC) e a doença pulmonar obstrutiva crônica (DPOC) são as mais comuns. Essas doenças apresentam produção aumentada de vários mediadores lipídicos, como LTB4 e PGE2. A PGE2 é um lipídeo imunossupressor atuante no sistema imune inato e adaptativo que regula, por exemplo, a liberação de citocinas e quimiocinas, a ativação de células T, além de inibir as funções efetoras dos macrófagos. O LTB4, por outro lado, está associado ao recrutamento de células para o foco infeccioso, a ativação dos mecanismos efetores dos macrófagos, e aumento de mediadores inflamatórios. Neste trabalho, nosso objetivo foi investigar se, esses mediadores são liberados durante a infecção pulmonar por A. xylosoxidans e o possível papel dos mesmos. Nossos resultados demonstram que os tratamentos com celecoxibe, inibidor da síntese de prostaglandinas (PGs), nas doses de 1mg/kg ou 5mg/kg, não alteram a sobrevida dos animais infectados com inóculo letal ou subletal de A. xylosoxidans. No entanto, o tratamento com MK886, um inibidor da produção de leucotrienos (LTs), resultou em aumento da mortalidade dos animais infectados com inóculos letal ou subletal, redução do recrutamento de neutrófilos no dia 1 após infecção, redução de IL-6 do dia 14 e aumento de TNF-, IL-1 e MIP-1 no dia 7, KC no dia 14 e PGE2, em todos os períodos estudados. Este tratamento também induziu no lavado broncoalveolar, a diminuição não significativa do extravasamento de proteínas no dia 1, mas aumento significativo no dia 3. Com base nesses dados, podemos sugerimos que o tratamento com MK886 aumenta a mortalidade dos animais, devido ao aumento da permeabilidade vascular, com consequente edema, que leva os animais a insuficiência respiratória. Outros experimentos serão realizados para determinar o papel das prostaglandinas (PGs) e/ou metabolitos do ácido araquidônico neste fenômeno. / Achromobacter xylosoxidans (A. xylosoxidans) is a gram negative bacilli, aerobic, mobile, glucose non fermenter and oxidase positive, which normally colonizes the digestive and auditory tract of humans. This bacillus has been associated with severe opportunistic infections, especially pneumonia, in immunocompromised individuals, which are generally difficult to control mainly due to virulence factors, mechanisms and exhaust multidrug resistance to antibiotic therapy. Among the conditions that predispose the development of pulmonary infection by A. xylosoxidans, cancer, cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) are the most common. These diseases have increased production of various lipid mediators, such as LTB4 and PGE2. PGE2 is an immunosuppressive lipid active in the innate and adaptive immune system that regulates, for example, the release of cytokines and chemokines, activation of T cells and inhibits the effector functions of macrophages. LTB4, on the other hand, is associated with the recruitment of cells to the infection, and the activation of effector mechanisms of macrophages, and increased production of inflammatory mediators. In this study, our aim was to investigate whether these mediators are released during pulmonary infection by A. xylosoxidans and the possible role of the same. Our results demonstrate that treatment with celecoxib, prostaglandin synthesis inhibitor (PGs), at doses of 1mg/kg or 5mg/kg not alter the survival of animals infected with lethal or sublethal inoculum of A. xylosoxidans. However, treatment with MK886, an inhibitor of the production of leukotrienes (LTs) resulted in an increased mortality of the animals infected with lethal or sublethal inoculum, reduce the recruitment of neutrophils on day 1 after infection, reduction in IL-6 day 14 and increased TNF-, IL-1 and MIP-1 at day 7, KC in day 14 and PGE2 in all periods. This treatment also induced in the bronchoalveolar lavage, no significant decrease protein extravasation in the day 1, but significantly increased on day 3. Based on these data, we suggest that treatment with MK886 increases the mortality of animals due to increased vascular permeability, with consequent edema, which leads the animals to respiratory failure. Other experiments will be conducted to determine the role of prostaglandins (PGs) and/or metabolites of arachidonic acid in this phenomenon.