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.

no / Dendritic cells (DCs) are central players in coordinating immune responses, both innate and adaptive. While the role of lipid mediators in the immune response has been the subject of many investigations, the precise role of prostaglandins has often been plagued by contradictory studies. In this study, we examined the role of PGE2 on human DC function. Although studies have suggested that PGE2 specifically plays a role in DC motility and cytokine release profile, the precise receptor usage and signaling pathways involved remain unclear. In this report we found that irrespective of the human donor, monocyte-derived dendritic cells (MoDCs) express three of the four PGE2 receptor subtypes (EP2–4), although only EP2 and EP4 were active with respect to cytokine production. Using selective EP receptor antagonists and agonists, we demonstrate that PGE2 coordinates control of IL-23 release (a promoter of Th17, an autoimmune associated T cell subset) in a dose-dependent manner by differential use of EP2 and EP4 receptors in LPS-activated MoDCs. This is in contrast to IL-12, which is dose dependently inhibited by PGE2 through both receptor subtypes. Low concentrations (∼1–10 nM) of PGE2 promoted IL-23 production via EP4 receptors, while at higher (>50 nM), but still physiologically relevant concentrations, IL-23 is suppressed by an EP2 dependent mechanism. These results can be explained by differential regulation of the common subunit, IL-12p40, and IL-23p19, by EP2 and EP4. By these means, PGE2 can act as a regulatory switch of immune responses depending on its concentration in the microenvironment. In addition, we believe these results may also explain why seemingly conflicting biological functions assigned to PGE2 have been reported in the literature, as the concentration of ligand (PGE2) fundamentally alters the nature of the response. This finding also highlights the potential of designing therapeutics which differentially target these receptors.

No / The skin produces bioactive lipids that participate in physiological and pathological states, including homeostasis, induction, propagation, and resolution of inflammation. However, comprehension of the cutaneous lipid complement, and contribution to differing roles of the epidermal and dermal compartments, remains incomplete. We assessed the profiles of eicosanoids, endocannabinoids, N-acyl ethanolamides, and sphingolipids, in human dermis, epidermis, and suction blister fluid. We identified 18 prostanoids, 12 hydroxy-fatty acids, 9 endocannabinoids and N-acyl ethanolamides, and 21 non-hydroxylated ceramides and sphingoid bases, several demonstrating significantly different expression in the tissues assayed. The array of dermal and epidermal fatty acids was reflected in the lipid mediators produced, whereas similarities between lipid profiles in blister fluid and epidermis indicated a primarily epidermal origin of suction blister fluid. Supplementation with omega-3 fatty acids ex vivo showed that their action is mediated through perturbation of existing species and formation of other anti-inflammatory lipids. These findings demonstrate the diversity of lipid mediators involved in maintaining tissue homeostasis in resting skin and hint at their contribution to signaling, cross-support, and functions of different skin compartments. Profiling lipid mediators in biopsies and suction blister fluid can support studies investigating cutaneous inflammatory responses, dietary manipulation, and skin diseases lacking biomarkers and therapeutic targets.

Receptor-Interacting Serine/Threonine Protein Kinase 2 (RIP2) is a kinase which modulates signaling downstream of the bacterial peptidoglycan sensors NOD1 and NOD2. It is known that activation of RIP2 by engaging NOD receptors increases the production of pro-inflammatory cytokine and lipid mediators. We have some data indicating that RIP2 may also be involved in specialized pro-resolution lipid mediator (SPM) production. However, the molecular mechanisms by which RIP2 is involved in lipid mediator biosynthesis, are currently unknown. Understanding this process may have significant implications for RIP2-targeted therapies, which may not only inhibit pro-inflammatory cytokine and lipid mediator production but may also disrupt SPM production and resolution programs. This thesis aims to demonstrate that RIP2 is involved in promoting the activation of ALOX5 in a transient overexpression setting but also in an endogenous setting using relevant bacterial stimuli. These aims were accomplished through the optimization of a fluorescent assay to assess ALOX5 enzymatic activity, by optimization of ALOX5 enzyme purification and through molecular cloning of ALOX5 into a retroviral vector followed by viral transduction of the THP-1 human monocytic cell line. We find that co-expression of RIP2 with ALOX5 significantly enhances the enzymatic activity of ALOX5. We have successfully cloned NTAP-tagged ALOX5 into the pBABE retroviral vector and are currently selecting transduced cells so that we might test if this effect also occurs endogenously. Understanding the mechanisms underlying the production and regulation of SPMs would provide greater insight into potential new therapeutic approaches to promote resolution in chronic inflammatory diseases.

La maladie d’Alzheimer (MA) est une démence progressive caractérisée dans ses stades précoces par une perte synaptique et une dégénérescence neuronale. Aucun traitement efficace n’est disponible à ce jour et les mécanismes moléculaires impliqués sont encore mal connus. Des études récentes, menées notamment par notre équipe, indiquent que les oligomères de peptide amyloïde-ß (Aß) interagissent avec la membrane plasmique et y induisent un stress cellulaire impliquant des cascades apoptotiques. Ce travail a été consacré à l’étude de l’influence du statut lipidique sur la sensibilité des neurones au peptide Aß soluble et sur la signalisation pro-apoptotique. Nous avons montré que ce peptide induit un remodelage membranaire conduisant à la mort neuronale en activant des voies pro-apoptotiques et en inhibant des voies de survie. Par contre, la supplémentation du milieu en acide docosahexaénoïque (DHA), acide gras polyinsaturé de type ?3, protège les neurones de la mort induite par le peptide Aß. Cet effet préventif semble dépendre d’une incorporation du DHA pouvant localement induire un remodelage membranaire discret capable de préserver des voies de croissance et de survie cellulaire. Le DHA n’agit toutefois pas en inhibant l’activation de la phospholipase A2 cytosolique (cPLA2) et le stress oxydant induits par le peptide Aß, mécanismes que nous avons observés être impliqués dans la voie pro-apoptotique menant à la production de céramides suite à l’activation des sphingomyélinases. Ces enzymes occupent une position essentielle dans la toxicité du peptide Aß, puisqu’un prétraitement par le DHA ou par la sphingosine-1-phosphate, connue pour son potentiel antiapoptotique, protège les neurones en inhibant la sphingomyélinase acide. Les travaux de cette thèse ont donc montré que les lipides, molécules structurales mais aussi médiateurs de signalisation, sont des acteurs essentiels à considérer pour le développement de stratégies préventives ou thérapeutiques contre la MA / Alzheimer’s disease (AD) is a progressive dementia characterised in the early stages by synaptic loss and neurodegeneration. Currently, no effective treatments are available and the molecular mechanisms implicated are still unknown. Recent studies, including ours, indicate that the direct interaction between soluble amyloid-ß (Aß) oligomers and the plasma membrane initiates a cellular stress involving apoptotic cascades. The present work focuses on the impact of lipid status on neuronal susceptibility to the toxicity of soluble Aß peptide and on the pro-apoptotic signalling pathways. We showed that this peptide induces membrane remodelling, thereby activating pro-apoptotic pathways and inhibiting survival signalling, which leads to neuronal cell death. This was however prevented in neurons cultured in a medium supplemented with docosahexaenoic acid (DHA), an ?3 polyunsaturated fatty acid. This protective effect seems to rely on subtle local membrane remodelling due to DHA incorporation, which maintains active survival and growth pathways. DHA did not prevent either cytosolic phospholipase A2 (cPLA2) or oxidative stress upon soluble Aß peptide exposure. These two events have already been reported by our team to be implicated in a pro-apoptotic cascade leading to ceramide production due to the activation of sphingomyelinases. These enzymes very likely play a central role in Aß peptide toxicity, as pretreatments with DHA or sphingosine-1-phosphate, a well-known anti-apoptotic compound, lead to neuronal protection through the inhibition of acid sphingomyelinase. This PhD thesis demonstrates that lipids, as structural molecules as well as signalling mediators, are essential players that could be used to develop strategies for the prevention or treatment of AD

In Acute Myocardial Infarction (AMI), inflammation is a prerequisite for healing but it can paradoxically extend tissue injury; hence it needs to be modulated. Here, we investigated the role of the pro resolving GPCR FPR2/ALX and its agonist Annexin A1 (AnxA1) in AMI using mice lacking of the Fpr2/3 genes and with an in-frame GFP gene ‘knocked-in’. We developed protocols aimed to determine GFP expression as an indication of Fpr2 gene activity. Also, the Left Anterior Descending Coronary Artery of male Fpr2/3 KO and littermate controls (WT) was occluded for 30min and re-opened for 90min. At the end tissue injury and inflammatory response were studied. A significant proportion of Fpr2/3 KO perished during the procedure. The rest survived up to 90 min and exhibited a larger infarct size, with higher troponin I and inflammation markers (KC, TNFα) than WT animals. At the end of reperfusion, Fpr2/3 KO displayed an unbalanced production of pro and anti-inflammatory lipids (higher PGE2, PGI2, LTB4 and attenuated PGA1, RvD2, LXA4) and a deregulated activation of the cardioprotective IL-6/JAK/STAT3 signalling. Administration of AnxA1 afforded cardioprotection (reduction of infarct size; Troponin I, Caspase3 activity and TNFα) in WT but not in Fpr2/3 KO. A parallel in vitro investigation on the functional FPR2/ALX domains required by AnxA1 and other agonists was also conducted. HEK-293 cells transfected with FPR1, FPR2/ALX and FPR1/FPR2 chimeric receptor were used and calcium flux, 4 pERK and gene modulation analysed. AnxA1 required the N-terminus and the II and III extracellular loops of FPR2/ALX to evoke canonical responses. SAA interacted/activated the I and the II extracellular loops of FPR2/ALX, whereas the compound 43 suffices the I extracellular loop. In summary, the FPR2/AnxA1 pathway exerts a protective role in AMI. AnxA1 mimetic that activated selective FPR2/ALX domains can be synthetize to prevent tissue damage caused by AMI.

As leishmanias são parasitas intracelulares obrigatórios que utilizam fagócitos (em especial os macrófagos), para sua sobrevivência e propagação. Estes parasitas são interiorizados via interação com diversos receptores da superfície celular, como o receptor CR3 (MAC-1; CD18/CD11b), componente da família das 2-integrinas. As B2-integrinas são importantes em diferentes mecanismos imunológicos, como a adesão e migração de células, fagocitose e modulação de vias de sinalização intracelulares. Estudos demonstram que a molécula CD18 (constituinte de todas as B2-integrinas) está envolvida na resposta imune na leishmaniose experimental, mas há controvérsias quanto a sua importância na defesa contra esta infecção. Leucotrienos e prostaglandinas são mediadores lipídicos envolvidos em diversos mecanismos da resposta imune inata e adaptativa. Na leishmaniose, os leucotrienos são considerados cruciais para a defesa do organismo por induzir mecanismos efetores celulares, como fagocitose e atividade microbicida. Por outro lado, as prostaglandinas (em especial PGE2) exercem efeito imunossupressor sobre estes mecanismos, podendo favorecer o desenvolvimento da doença. Entretanto, não há conhecimento sobre a relação entre a expressão das B2-integrinas e a produção destes mediadores lipídicos na leishmaniose e a importância destas moléculas na resposta imune contra esta infecção. Assim, o objetivo desta tese foi investigar o efeito da redução da expressão das B2-integrinas na produção de citocinas, quimiocinas e de medidores lipídicos, em modelo de infecção experimental por L. amazonensis. Para isso, camundongos da linhagem C57BL/6 selvagens (WT) e com baixa expressão de CD18 (CD18 Low), foram infectados com promastigotas de L. amazonensis na pata posterior, e o desenvolvimento da infecção foi acompanhado por 5 e 8 semanas após a inoculação. Com base nos resultados obtidos, os animais CD18 Low apresentaram maior carga parasitária nas patas, em comparação com os camundongos selvagens. Além disso, a maior suscetibilidade dos camundongos CD18 Low foi independente da produção de NO e de IL-10 e da redução de IL-12 mediada por IL-4. Estes animais também apresentaram reduzida produção de IFN-gama. Além disso, os camundongos CD18 Low tiveram alterações na produção de LTB4 e de PGE2 ,as quais podem ter reduzido as respostas efetoras das células no sítio da infecção. Também demonstramos que a migração de neutrófilos e de eosinófilos para o sítio de infecção ocorreu de modo independente da expressão de CD18. O maior edema e recrutamento de eosinófilos nas patas dos camundongos CD18 Low foi independente da produção de MCP-1 e parcialmente dependente de RANTES. Entretanto, a produção de LTC4 pareceu ter sido o principal responsável por estes efeitos, em conjunto com PGD2. Deste modo, nossos resultados mostram que a baixa expressão de CD18 favorece o desenvolvimento da infecção por L. amazonensis. / Leishmania are obligate intracellular parasites that use phagocytes (especially macrophages) for their survival and propagation. These parasites are internalized through interaction with several receptors of cellular surface, such as the CR3 receptor (Mac-1; CD18/CD11b), component of the B2-integrins family. B2- integrins are involved in important immune mechanisms, such as cell adhesion, cell migration, phagocytosis and modulation of intracellular signaling pathways. Studies have shown that the CD18 molecule (component of all B2-integrins), is involved in the immune response in experimental leishmaniasis, but its importance in the host defense against this infection is still controversial. Leukotrienes and prostaglandins are lipid mediators involved in various mechanisms of innate and adaptive immune response. In leishmaniasis, leukotrienes are considered critical for the host defense, once it induces cellular effector mechanisms such as phagocytosis and microbicide activity. On the other hand, prostaglandins (in particular PGE2), lead to immunosuppressive effects on these mechanisms and may favor development of disease. However, it is unknown whether there is an interaction between the B2 integrins expression and the production of these mediators in leishmaniasis and the role of these molecules in host defense against this disease. Thus, the aim of this thesis was to verify the effect of reduced expression of B2-integrins in cytokines, chemokines and lipid mediators production, in experimental model of L. amazonensis infection. For this purpose, wild type mice (WT) and mice with reduced CD18 expression (CD18Low) from C57BL/6 strain were infected with L. amazonensis promastigotes in the hind footpad. The development of the infection was assessed for 5 and 8 weeks after inoculation. Our results showed that the CD18Low mice had higher parasite load in footpad, compared to wild-type mice. Moreover, the higher susceptibility of CD18Low mice was independent of NO and IL-10 production and independent of IL-12 reduction mediated by IL-4. These mice also showed reduced IFN- gamma production. CD18Low mice had alterations in LTB4 and PGE2 levels in site of infection, which may have altered the effector cell responses. We also demonstrated that the migration of neutrophils and eosinophils to the site of infection was CD18-independent. Moreover, the higher edema and eosinophils recruitment in CD18Low mice was MCP-1-independent and partially dependent of RANTES. However, LTC4 production seemed to be the main factor for edema and migration of eosinophils, together with PGD2. Thus, our results show that the reduction on CD18 expression favors the development of L. amazonensis infection.

As leishmanias são parasitas intracelulares obrigatórios que utilizam fagócitos (em especial os macrófagos), para sua sobrevivência e propagação. Estes parasitas são interiorizados via interação com diversos receptores da superfície celular, como o receptor CR3 (MAC-1; CD18/CD11b), componente da família das 2-integrinas. As B2-integrinas são importantes em diferentes mecanismos imunológicos, como a adesão e migração de células, fagocitose e modulação de vias de sinalização intracelulares. Estudos demonstram que a molécula CD18 (constituinte de todas as B2-integrinas) está envolvida na resposta imune na leishmaniose experimental, mas há controvérsias quanto a sua importância na defesa contra esta infecção. Leucotrienos e prostaglandinas são mediadores lipídicos envolvidos em diversos mecanismos da resposta imune inata e adaptativa. Na leishmaniose, os leucotrienos são considerados cruciais para a defesa do organismo por induzir mecanismos efetores celulares, como fagocitose e atividade microbicida. Por outro lado, as prostaglandinas (em especial PGE2) exercem efeito imunossupressor sobre estes mecanismos, podendo favorecer o desenvolvimento da doença. Entretanto, não há conhecimento sobre a relação entre a expressão das B2-integrinas e a produção destes mediadores lipídicos na leishmaniose e a importância destas moléculas na resposta imune contra esta infecção. Assim, o objetivo desta tese foi investigar o efeito da redução da expressão das B2-integrinas na produção de citocinas, quimiocinas e de medidores lipídicos, em modelo de infecção experimental por L. amazonensis. Para isso, camundongos da linhagem C57BL/6 selvagens (WT) e com baixa expressão de CD18 (CD18 Low), foram infectados com promastigotas de L. amazonensis na pata posterior, e o desenvolvimento da infecção foi acompanhado por 5 e 8 semanas após a inoculação. Com base nos resultados obtidos, os animais CD18 Low apresentaram maior carga parasitária nas patas, em comparação com os camundongos selvagens. Além disso, a maior suscetibilidade dos camundongos CD18 Low foi independente da produção de NO e de IL-10 e da redução de IL-12 mediada por IL-4. Estes animais também apresentaram reduzida produção de IFN-gama. Além disso, os camundongos CD18 Low tiveram alterações na produção de LTB4 e de PGE2 ,as quais podem ter reduzido as respostas efetoras das células no sítio da infecção. Também demonstramos que a migração de neutrófilos e de eosinófilos para o sítio de infecção ocorreu de modo independente da expressão de CD18. O maior edema e recrutamento de eosinófilos nas patas dos camundongos CD18 Low foi independente da produção de MCP-1 e parcialmente dependente de RANTES. Entretanto, a produção de LTC4 pareceu ter sido o principal responsável por estes efeitos, em conjunto com PGD2. Deste modo, nossos resultados mostram que a baixa expressão de CD18 favorece o desenvolvimento da infecção por L. amazonensis. / Leishmania are obligate intracellular parasites that use phagocytes (especially macrophages) for their survival and propagation. These parasites are internalized through interaction with several receptors of cellular surface, such as the CR3 receptor (Mac-1; CD18/CD11b), component of the B2-integrins family. B2- integrins are involved in important immune mechanisms, such as cell adhesion, cell migration, phagocytosis and modulation of intracellular signaling pathways. Studies have shown that the CD18 molecule (component of all B2-integrins), is involved in the immune response in experimental leishmaniasis, but its importance in the host defense against this infection is still controversial. Leukotrienes and prostaglandins are lipid mediators involved in various mechanisms of innate and adaptive immune response. In leishmaniasis, leukotrienes are considered critical for the host defense, once it induces cellular effector mechanisms such as phagocytosis and microbicide activity. On the other hand, prostaglandins (in particular PGE2), lead to immunosuppressive effects on these mechanisms and may favor development of disease. However, it is unknown whether there is an interaction between the B2 integrins expression and the production of these mediators in leishmaniasis and the role of these molecules in host defense against this disease. Thus, the aim of this thesis was to verify the effect of reduced expression of B2-integrins in cytokines, chemokines and lipid mediators production, in experimental model of L. amazonensis infection. For this purpose, wild type mice (WT) and mice with reduced CD18 expression (CD18Low) from C57BL/6 strain were infected with L. amazonensis promastigotes in the hind footpad. The development of the infection was assessed for 5 and 8 weeks after inoculation. Our results showed that the CD18Low mice had higher parasite load in footpad, compared to wild-type mice. Moreover, the higher susceptibility of CD18Low mice was independent of NO and IL-10 production and independent of IL-12 reduction mediated by IL-4. These mice also showed reduced IFN- gamma production. CD18Low mice had alterations in LTB4 and PGE2 levels in site of infection, which may have altered the effector cell responses. We also demonstrated that the migration of neutrophils and eosinophils to the site of infection was CD18-independent. Moreover, the higher edema and eosinophils recruitment in CD18Low mice was MCP-1-independent and partially dependent of RANTES. However, LTC4 production seemed to be the main factor for edema and migration of eosinophils, together with PGD2. Thus, our results show that the reduction on CD18 expression favors the development of L. amazonensis infection.

Background: A significant portion of lactating women in less developed countries have vitamin A (VA) deficiency. Lactation has substantial effects on a mother’s metabolism and VA is known to be needed in multiple biological processes, including growth, vision, immunity, and reproduction. Objective: The objective of this pilot study was to utilize metabolomics profiling to conduct a broad, exploratory assessment of differences in plasma metabolites associated with low VA status versus adequacy in lactating women. Methods: Plasma samples from lactating women who participated in a survey in Samar, Philippines, were selected from a cross-sectional study based on plasma retinol concentrations indicating low (VA-; n=5) or adequate (VA+; n=5) VA status (plasma retinol <0.7 or >1.05 µmol/L). The plasma results collected from six metabolomics assays (oxylipins, endocannabinoids, bile acids, primary metabolomics, aminomics, and lipidomics) were compared by group, using liquid chromatography mass spectrometry. Results: Twenty-eight metabolites were significantly different in the VA- versus VA+ status, with 24 being lipid mediators (p<0.05). The lipid mediators demonstrated lower concentrations of the arachidonic acid- and eicosapentaenoic acid-derived oxylipins, as well as lysophospholipids and sphingolipids, in the VA- group (p<0.05). Chemical similarity enrichment analysis identified HETEs, HEPEs, and DiHETEs as significantly different oxylipin clusters (p<0.0001, false discovery rate (FDR) p<0.0001), as well as sphingomyelins, saturated lysophosphatidylcholines, phosphatidylcholines, and phosphatidylethanolamines (p<0.001, FDR p<0.01). Conclusions: The multi-assay nutritional metabolomics profiling of low VA status compared with adequacy in lactating women demonstrated reduced lipid mediator concentrations. Future studies with stronger study designs and a large and more diverse population are needed to validate these preliminary results.

Lipids are important for structural and physiological functions of neuronal cell membranes. They exhibit a range of biological effects many are bioactive lipid mediators derived from polyunsaturated fatty acids such as sphingolipids, fatty acid ethanolamides (FA-EA) and endocannabinoids (EC). These lipid mediators and oxysterols elicit potent bioactive functions in many physiological and pathological processes of the brain and neuronal tissues. They have been investigated for biomarker discovery of ageing, neuroinflammation and neurodegenerative disorders. The n-3 fatty acids EPA and DPA are thought to exhibit a range of neuroprotective effects many of which are mediated through production of such lipid mediators. The aims of this study were to evaluate the effects of n-3 EPA and n-3 DPA supplementation on RBC membranes and in this way assess dietary compliance and to investigate brain sphingomyelin species of adult and aged rats supplemented with n-3 EPA and n-3 DPA to evaluate the effects and benefits on age-related changes in the brain. Furthermore, to study the effects of lithium on the brain FA-EAs and ECs to further understand the neuroprotective effects of lithium neuroprotective action on neuroinflammation as induced by LPS. Finally to examine if circulating oxysterols are linked to the prevalence of ALS and whether RBC fatty acids are markers of this action in relation to age and disease stages. These analytes were extracted from tissue samples and analysed with GC, LC/ESI-MS/MS and GC-MS. It was found that aged rats exhibited a significant increase in brain AA and decrease in Σn-3 and Σn-6 PUFAs when compared to adult animals. The observed increase of brain AA was reversed following n-3 EPA and n-3 DPA supplementation. Sphingomyelin was significantly increased when aged animals were supplemented with n-3 DPA. LPS treatment following lithium supplementation increased LA-EA and ALA-EA, while it decreased DHA-EA. Both oxysterols 24-OH and 27-OH increased in ALS patients and SOD1-mice. Eicosadienoic acid was different in ASL-patients compared to aged SOD1-mice. These studies demonstrated that dietary intake of n-3 EPA and n-3DPA significantly altered RBC fatty acids and sphingolipids in rat brain. They suggest that n-3 DPA can be a potential storage form for EPA, as shown by retro-conversion of n-3 DPA into EPA in erythrocyte membranes, ensuring supply of n-3 EPA. Also, n-3 EPA and n-3 DPA supplementation can contribute to an increase in brain sphingomyelin species with implications for age effects and regulation of brain development. Effects of lithium highlight novel anti-neuroinflammatory treatment pathways. Both 24-hydroxycholesterol and eicosadienoic acid may be used as biomarkers in ALS thereby possibly helping to manage the progressive stages of disease.