Phospholipase D in brain function and Alzheimer's disease

Alzheimer's disease is the most common neurodegenerative disorder. Although lipids are major constituents of brain, their role in Alzheimer's disease pathogenesis is poorly understood. Much attention has been given to cholesterol, but growing evidence suggests that other lipids, such as phospholipids, might play an important role in this disorder. In this review, we will summarize the evidence linking phospholipase D, a phosphatidic acid-synthesizing enzyme, to multiple aspects of normal brain function and to Alzheimer's disease. The role of phospholipase D in signaling mechanisms downstream of beta-amyloid as well as in the trafficking and processing of amyloid precursor protein will be emphasized.We would like to thank Robin Chan, Samuel Frere, KimberlyRobinson, and Zachary Freyberg for critical reading of the manuscript.Work from T.G.O. is supported by the Portuguese Foundation forScience and Technology SFRH/BD/33237/2007 and the Luso-Amer-ican Development Foundatio

The role of phospholipase D2 in Alzheimer's disease

Tese de doutoramento em Ciências da Saúde (ramo do conhecimento em Medicina)Growing evidence implicates aberrant lipid signaling in Alzheimer‟s disease (AD). While phospholipases A2 and C have been recently shown to mediate key actions of amyloid β-peptide (Aβ) through a dysregulation of arachidonic acid and phosphatidylinositol-4,5-bisphosphate metabolism, respectively, the role of phospholipase D (PLD) has so far remained elusive. PLD produces phosphatidic acid (PA), a bioactive lipid involved in multiple aspects of cell physiology, including signaling and membrane trafficking processes. Here we show that oligomeric Aβ enhances PLD activity in cultured neurons and that this stimulatory effect does not occur upon ablation of PLD2 via gene targeting. Aβ fails to suppress long-term potentiation in PLD2-deficient hippocampal slices, suggesting that PLD2 is required for the synaptotoxic action of this peptide. In vivo PLD activity, as assessed by detection of phosphatidylethanol levels using mass spectrometry (MS) following ethanol injection, is also increased in the brain of a transgenic mouse model of AD (SwAPP). Furthermore, Pld2 ablation rescues memory deficits and confers synaptic protection in SwAPP mice despite a significant Aβ load. MS-based lipid analysis of Pld2 mutant brains in the presence or absence of the SwAPP transgene unmasks striking crosstalks between different PA species. This lipid analysis shows an exquisite acyl chain specificity and plasticity in the perturbation of PA metabolism, with the notable elevation in SwAPP brains of a pool of PA previously linked to degeneration. Collectively, our results point to specific molecular species of PA as key modulators of AD pathogenesis and identify PLD2 as a novel potential target for therapeutics. Moreover we expanded our MS analysis of the Pld2/SwAPP mice to other lipid groups, other than PA. We found that overexpression of the SwAPP transgene leads to significant increase in the ganglioside, GM3. Remarkably, Pld2 ablation leads to a decrease in GM3 in the non-transgenic background and to a rescue to normals in the SwAPP background. This lipidomic analysis uncovered interesting lipid signaling crosstalks that are modulated by PLD2 in the context of AD models.Trabalhos anteriores indicam que distúrbios no metabolismo dos lípidos estão relacionados com a doença de Alzheimer (AD). Enquanto que as fosfolipases A2 e C foram demonstradas como mediadoras das acções do péptido, amilóide beta (Aβ), através da desregulação do metabolismo do ácido araquidónico e fosfoinositol-4,5-bifosfato, respectivamente, o papel da fosfolipase D (PLD) permanence por esclarecer. A PLD produz ácido fosfatídico (PA), um lípido envolvido em múltiplos aspectos da fisiologia cellular, como vias de sinalização e tráfico membranar. Neste trabalho, mostramos que oligómeros de Aβ levam a um aumento da actividade da PLD em culturas primárias de neurónios e que esse efeito estimulatório não ocorre após a delecção genética da PLD2. A Aβ perde o seu efeito suppressor de potenciação de longo termo em fatias de hipocampo de ratinhos Pld2--/-, sugerindo que a PLD2 é necessária para o efeito sinaptotóxico deste péptido. A actividade da PLD in vivo, medida através da detecção dos níveis de fosfatidiletanol, por espectrometria de massa (MS) após injecção de etanol, também está aumentada no cérebro de um modelo transgénico de AD (SwAPP). Para além disso a ablação da Pld2 recupera os défices de memória e leva a uma protecção sináptica em ratinhos SwAPP, apesar dos altos níveis de Aβ. Análise de lípidos por MS de cérebros de ratinhos mutantes para a Pld2 na presença ou ausência do transgene SwAPP revela haver uma intensa intraregulação nas espécies de PA. Esta análise lipídica mostra uma especificidade e plasticidade no modo como o metabolismo do PA está alterado, com uma marcada elevação nos cérebros SwAPP de uma espécie de PA previamente ligado a processos neurodegenerativos. Em suma, os nossos resultados apontam para espécies específicas de PA como moduladores da patogénese da AD e identificam a PLD2 como um novo alvo potencial terapêutico. Além disso, expandimos a nossa análise por MS para outros lípidos, para além de PA. Observámos que a sobreexpressão do transgene SwAPP leva a um aumento do gangliosídeo, GM3. A ablação genética de Pld2 leva a um decréscimo de GM3 nos animais não-transgénicos e a uma renormalização dos valores nos animais SwAPP. Em conclusão, esta análise lipidómica revelou ligações mecanísticas interessantes reguladas pela PLD2, no contexto da AD

Brain MRI in a patient with classical galactosemia: acute event of unilateral hemispheric cerebral edema

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A quick and low-intensity method for oral administration to large numbers of mice: A possible alternative to oral gavage

Oral administration of medication to experimental animals is a cause of significant stress. When coupled to animals who are already under strenuous circumstances due to the disease being modelled, there is a significant risk for increased morbidity and mortality, thus influencing the results. Faced with these con- straints, a low-intensity method for oral administration was developed, based solely on the natural behaviour of the animals and minimal conditioning, in which precise doses of medication were administered in a locally available, standard wheat cookie fragment, providing both a palatable vehicle and an absorbent matrix for the medication. Fast administration to large numbers of animals was thus achieved, safeguarding the animals’ welfare and ensuring ease of handling. This method is a promising alternative to oral gavage in pre-clinical drug studies with laboratory mice

Phospholipase D functional ablation has a protective effect in an Alzheimer's disease Caenorhabditis elegans model

Phospholipase D (PLD) is a key player in the modulation of multiple aspects of cell physiology and has been proposed as a therapeutic target for Alzheimer's disease (AD). Here, we characterize a PLD mutant, pld-1, using the Caenorhabditis elegans animal model. We show that pld-1 animals present decreased phosphatidic acid levels, that PLD is the only source of total PLD activity and that pld-1 animals are more sensitive to the acute effects of ethanol. We further show that PLD is not essential for survival or for the normal performance in a battery of behavioral tests. Interestingly, pld-1 animals present both increased size and lipid stores levels. While ablation of PLD has no important effect in worm behavior, its ablation in an AD-like model that overexpresses amyloid-beta (Aβ), markedly improves various phenotypes such as motor tasks, prevents susceptibility to a proconvulsivant drug, has a protective effect upon serotonin treatment and reverts the biometric changes in the Aβ animals, leading to the normalization of the worm body size. Overall, this work proposes the C. elegans model as a relevant tool to study the functions of PLD and further supports the notion that PLD has a significant role in neurodegeneration.We would like to thank members of the Oliveira and Maciel labs for discussions, for critical analysis of data and discussions on the manuscript. Ricardo Rosa for his technical assistance in lifespan assays and Carlos Bessa for his technical suggestions. Thanks to the Caenorhabditis Genetics Center (CGC), which is funded by the National Institutes of Health – National Center for Research Resources, for some of the nematode strains. Costs with acquisition and transfer of genetic C. elegans models were covered by Tiago Gil Oliveira. This work was supported by grants from the Portuguese North Regional Operational Program (ON.2 – O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER), the Portuguese Foundation for Science and Technology PD/BD/52286/2013 (Francisca Vaz Bravo) as well as NIH ADRC grant P50 AG008702 to Scott A. Small (project G.D.P.) and NIH grant R21 AG045020 to G.D.P.info:eu-repo/semantics/publishedVersio

Interplay between Depressive-Like Behavior and the Immune System in an Animal Model of Prenatal Dexamethasone Administration

Glucocorticoids, namely dexamethasone, are prescribed during late gestation in pregnancies at risk of originating premature newborns, to promote fetal lung maturation. However, adverse early life events have been reported to induce long-lasting changes in the immune and central nervous systems. The accumulating evidence on bidirectional interactions between both systems in psychiatric disorders like depression, prompted us to further investigate the long-term impact of prenatal dexamethasone administration in depressive-like behavior, the immune system and in the ability to mount an immune response to acute infection. The adult male offspring of pregnant dams treated with dexamethasone present depressive-like behavior concomitant with a decrease in CD8+ T lymphocytes and an increase in B and CD4+ regulatory T cells. This is accompanied by lower levels of serum interleukin-6 (IL-6) and IL-10. Despite of these differences, when spleen cells are stimulated, in vitro, with lipopolysaccharide, those from adult rats prenatally treated with dexamethasone display a stronger pro-inflammatory cytokine response. However, this immune system profile does not hamper the ability of rats prenatally treated with dexamethasone to respond to acute infection by Listeria monocytogenes. Of notice, L. monocytogenes infection triggers depressive-like behavior in control animals but does not worsen that already present in dexamethasone-treated animals. In summary, prenatal administration of dexamethasone has long-lasting effects on the immune system and on behavior, which are not further aggravated by acute infection with L. monocytogenes

Aeromonas spp. prevalence, virulence and antimicrobial resistance in an ex situ program for threatened freshwater fish – a pilot study with protective measures

This research was supported by CIISA - Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade de Lisboa, Project UIDB/00276/2020 (funded by FCT - Fundação para a Ciência e Tecnologia IP), by MARE (MARE-ISPA), MARE/UIDB/MAR/04292/2020 and strategic project MARE/UIDP/MAR/04292/2020 (also funded by FCT) and by the Zebra Foundation for Veterinary Zoological Education, Grant “A. hydrophila in Iberochondrostoma lusitanicum”. MLG thanks funding by the University of Lisbon (PhD fellowship C10571K). TAM and CM thank partial support by CEAUL (funded by FCT, Portugal, through the project UIDB/00006/2020).Ex situ breeding programs are important conservation tools for endangered freshwater fish. However, developing husbandry techniques that decrease the likelihood of disease, antimicrobial resistance, and virulence determinants acquisition during this process is challenging. In this pilot study, we conducted a captivity experiment with Portuguese nase (Iberochondrostoma lusitanicum), a critically endangered leuciscid species, to investigate the influence of simple protective measures (i.e., material disinfection protocols and animal handling with gloves) on the dynamics of a potential pathogenic genus, Aeromonas, as well as its virulence profiles and antimicrobial resistance signatures. Our findings show that antimicrobial resistance in Aeromonas spp. collected from I. lusitanicum significantly increased during the extent of the assay (5 weeks), with all isolates collected at the end of the study classified as multidrug-resistant. Additionally, humans handling fishes without protective measures were colonized by Aeromonas spp. The use of protective measures suggested a decreasing trend in Aeromonas spp. prevalence in I. lusitanicum, while bacterial isolates displayed significantly lower virulence index values when virulence phenotypical expression was tested at 22 °C. Despite this study representing an initial trial, which needs support from further research, protective measures tested are considered a simple tool to be applied in ex situ breeding programs for aquatic animals worldwide. Furthermore, current results raise concern regarding antimicrobial resistance amplification and zoonotic transmission of Aeromonas spp. in aquatic ex situ programs.Publisher PDFPeer reviewe

Gadolinium ecotoxicity is enhanced in a warmer and acidified changing ocean as shown by the surf clam Spisula solida through a multibiomarker approach

Funding Information: This work was supported by Fundação para a Ciência e Tecnologia (FCT) , through the project Climatoxeel ( PTDC/AAG-GLO/3795/2014 ), by the Junior Researcher contract ( CEECIND/03517/2017 ), both awarded to Tiago F. Grilo, and the strategic project UIDB/04292/2020 granted to MARE and through project LA/P/0069/2020 granted to the Associate Laboratory ARNET . The work was also supported by the European Union's operation program Mar 2020 through the research project CEIC ( MAR-01.04.02-FEAMP-0012 ) awarded to Joana Raimundo. The Applied Molecular Biosciences Unit UCIBIO was financed by national funds from FCT ( UIDP/04378/2020 ). This work was also supported by the European Union through the grant ERC-2016-COG-725034 -ecotox awarded to Inês João Ferreira. Cátia Figueiredo acknowledges the FCT-PhD grant SFRH/BD/130023/2017 and the Early Career Research Grant awarded by National Geographic Society. Publisher Copyright: © 2022 The Author(s)Humans have exhaustively combusted fossil fuels, and released pollutants into the environment, at continuously faster rates resulting in global average temperature increase and seawater pH decrease. Climate change is forecasted to exacerbate the effects of pollutants such as the emergent rare earth elements. Therefore, the objective of this study was to assess the combined effects of rising temperature (Δ = + 4 °C) and decreasing pH (Δ = − 0.4 pH units) on the bioaccumulation and elimination of gadolinium (Gd) in the bioindicator bivalve species Spisula solida (Surf clam). We exposed surf clams to 10 µg L−1 of GdCl3 for seven days, under warming, acidification, and their combination, followed by a depuration phase lasting for another 7 days and investigated the Gd bioaccumulation and oxidative stress-related responses after 1, 3 and 7 days of exposure and the elimination phase. Gadolinium accumulated after just one day with values reaching the highest after 7 days. Gadolinium was not eliminated after 7 days, and elimination is further hampered under climate change scenarios. Warming and acidification, and their interaction did not significantly impact Gd concentration. However, there was a significant interaction on clam's biochemical response. The augmented total antioxidant capacity and lipid peroxidation values show that the significant impacts of Gd on the oxidative stress response are enhanced under warming while the increased superoxide dismutase and catalase values demonstrate the combined impact of Gd, warming & acidification. Ultimately, lipid damage was greater in clams exposed to warming & Gd, which emphasizes the enhanced toxic effects of Gd in a changing ocean.publishersversionpublishe

Ocean warming, acidification, and rare earth elements exposure triggers a superior antioxidant response and pigment production in the adaptable Ulva rigida

European Union's operation program Mar 2020 through the research project CEIC (MAR-01.04.02-FEAMP-0012). Inês João Ferreira acknowledges the European Union research grant ERC-2016-COG-725034-ecotox. Publisher Copyright: © 2022 The Author(s)Anthropogenic increased atmospheric CO2 concentrations will lead to a drop of 0.4 units of seawater pH and ocean warming up to 4.8°C by 2100. Contaminant's toxicity is known to increase under a climate change scenario. Rare earth elements (REE) are emerging contaminants, that until now have no regulation regarding maximum concentration and discharge into the environment and have become vital to new technologies such as electric and hybrid-electric vehicle batteries, wind turbine generators and low-energy lighting. Studies of REE, namely Lanthanum (La) and Gadolinium (Gd), bioaccumulation, elimination, and toxicity in a multi-stressor environment (e.g., warming and acidification) are lacking. Hence, we investigated the algae phytoremediation capacity, the ecotoxicological responses and total chlorophyll and carotenoid contents in Ulva rigida during 7 days of co-exposure to La or Gd (15 µg L−1 or 10 µg L−1, respectively), and warming and acidification. Additionally, we assessed these metals elimination, after a 7-day phase. After one day of experiment La and Gd clearly showed accumulation/adsorption in different patterns, at future conditions. Unlikely for Gd, Warming and Acidification contributed to the lowest La accumulation, and increased elimination. Lanthanum and Gd triggered an adequate activation of the antioxidant defence system, by avoiding lipid damage. Nevertheless, REE exposure in a near-future scenario triggered an overproduction of ROS that requested an enhanced antioxidant response. Additionally, an increase in total chlorophyll and carotenoids could also indicate an unforeseen energy expense, as a response to a multi-stressor environment.publishersversionpublishe