Browsing by Author "Duarte, E.L."
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- Aflatoxin B1 and early life gut microbiota: preliminary results under earlyMYCO projectPublication . Silva, I.; Duarte, E.L.; Bastos-Amador, P.; Ferreira, M.; Alvito, P.; Assunção, R.; Salvador, C.; Caldeira, A.TAflatoxin B1 (AFB1) produces acute or chronic deleterious health effects in humans and animals. Still, long-term effects derived from initial exposure in early-life, a critical period for colonization and development of gut microbiota, has not been fully evaluated, . particularly, effects on gut microbiota and immunity system. This study, performed under the earlyMYCO project, investigated the impact of maternal exposure to AFB1 on early-life microbiota in a mouse model. Females were fed jelly pellets containing 400 µg/kg AFB1 diluted in DMSO (treated animals n=6) or DMSO vehicle alone (control group n=6) during pregnancy and lactation. Faeces from the offspring were collected immediately after weaning and faecal DNA was extracted and purified. Bacterial taxa diversity and relative abundance were assessed by High-Throughput Sequencing performed in an Illumina Miseq® sequencer, targeting the V3 and V4 regions of the 16S rRNA gene. Operational taxonomic units (OTUs) were determined by clustering reads to 16S reference databases. A hundred and twenty-four (N=124) bacterial genera were found in both groups, 5 were only present in AFB1 treated group and 27 exclusively in control groups. A hundred and fifty-one (N=151) bacterial species were common to both groups, 15 species exclusively found in AFB1 litters and 34 species were exclusively found in control litters. Although present in both groups, Akkermansia muciniphila and Bacteroides acidifaciens were significantly higher in controls. A. muciniphila colonizes the intestinal tract in childhood and regulates mucus thickness, intestinal barrier integrity and is involved in immune modulation. B. acidifaciens participates in the metabolism of lipids and sugars and activates some cytokines and immune cell receptors. Sulfidogenic bacteria, recently related to inflammatory bowel disease, such as Desulfovibrio piger and Bilophila wadsworthia were exclusivly found in the treated litters. Early-life gut microbiome triggers the gut immune defences, but is far less stable than the adult microbiome. These preliminary results open an extensive field to further investigate the association between mycotoxins and microbiome, as the latest is increasingly recognized as a major player in a wide spectrum of diseases.
- Children Exposure to Multiple Mycotoxins through Food Consumption: A Holistic Approach for Risk AssessmentPublication . Assunção, Ricardo; Vasco, Elsa; Duarte, E.L.; Alvito, PaulaHumans can be exposed to multiple chemicals at once from a variety of sources, and human risk assessment of multiple chemicals poses several challenges to scientists, risk assessors and risk managers and opens new avenues for research. Ingestion of food is considered a major route of exposure to many contaminants, namely mycotoxins. Mycotoxins are natural contaminants produced by fungi and its common occurrence in food poses a threat to human health, mainly to vulnerable population groups as children. Nowadays, there is an increasing evidence that mycotoxins co-contamination of food matrices is the rule, not the exception. Likewise, the growing concern about the combined effects of mycotoxins and their potential impact on human health has been reflected by the increasing number of toxicological studies on the combined toxicity of these compounds. Nevertheless, risk assessment of these toxins, still follows the conventional paradigm of single exposure and single effects, incorporating only the possibility of additivity but not taking into account the complex dynamics associated to interactions between different mycotoxins or between mycotoxins and other food contaminants. The intestinal mucosa is the first biological barrier encountered by natural toxins, and consequently, it could be exposed to high amounts of dietary toxins as mycotoxins, and consequently the assessment of the toxic effects resulting from exposure to these compounds constitutes a crucial step within mycotoxins risk assessment. The present PhD project aimed to study Portuguese children exposure to multiple mycotoxins through food consumption applying a holistic approach for risk assessment. Additionally, the present study intended to assess the impact of multiple mycotoxins exposure on intestinal mucosa. To attain these objectives, some first-line approaches were developed/applied, namely 1) development and application of new analytical techniques on mycotoxin multiple detection and quantification, 2) understand the toxicity responses upon multiple mycotoxin exposures, with especial focus on intestinal mucosa, and 3) implement new methodologies to characterize hazard and risk for children exposure to mycotoxins. The holistic approach gathered data obtained through different approaches, including the application of deterministic and probabilistic tools to the calculation of mycotoxin daily intake values, the integration of children (under 3 years old) food consumption (3-days food diary), mycotoxins occurrence in food intended for children consumption, bioaccessibility and toxicological data. Main results showed that children exposure to ochratoxin A (OTA), fumonisins, trichothecenes and zearalenone indicate no health concern for individuals exposed to these mycotoxins through consumption of breakfast cereals, processed cereal-based products and biscuits. Contrary to other, aflatoxins exposure suggested a potential health concern for the high percentiles of intake. When analysed the combined toxic effect of patulin (PAT) and OTA in the intestinal membrane integrity, the results suggested a dose level deviation with synergism at low doses and antagonism at higher doses. Given that mycotoxin concentrations in real scenarios are generally low, especial attention should be dedicated to the mixture PAT and OTA, especially for the potential consequences of loss of membrane integrity and the potential contribution to the development of intestinal diseases. The present work underlines the need to adopt a holistic approach for multiple mycotoxins risk assessment integrating data from exposure, bioaccessibility and toxicity domains in order to contribute to a more accurate risk assessment.
- How maternal exposure to aflatoxin B1 impacts the development of progeny intestinal immune system?Publication . Bastos-Amador, P.; Duarte, E.L.; Alvito, P.; Assunção, R.; Ferreira, M.
- How maternal exposure to aflatoxin B1 impacts the development of progeny intestinal immune system?Publication . Bastos-Amador, P.; Duarte, E.L.; Alvito, P.; Assunção, R.; Ferreira, M.Exposure to toxic contaminants during early-life is associated with the development of diseases. Individuals are exposed to mycotoxins since early stages of life[1]. However how maternal exposure to mycotoxins influences the development and function of the offspring’s immune system remains largely unexplored. Recently, we showed that in utero maternal exposure to micronutrients is critical for the development of the immune system, which sets long term immunity if the progeny[2]. Here we show that presence of aflatoxin B1 in the diet of pregnant murine females affects the development and function of the intestinal immune system. Notably, maternal exposure to AFB1 promoted an increase of overall T cell population, while it also resulted in a selective reduction of cytokine-producing innate lymphoid cells group 2 (ILC2) population in intestine of the progeny. These alterations were associated with decreased expression of Reg3b, Reg3g and Fut2 by the intestinal mucosa of progeny. Thus, these results indicate that maternal exposure to mycotoxins impacts the development of offspring intestinal immune system. ILC2 are critical in intestinal epithelial repair, whether mice exposed to AFB1 display defective tissue damage response needs to be investigated. Also FUT2-dependent fucosylation is key in host–commensal symbiosis suggesting alterations in the intestinal microbiota. Our work reveals that maternal exposure to dietary contaminants such as mycotoxins alters the normal development of intestinal immune system framework of the progeny and may have impact in their immune function.
- Screening of mosquitoes as vectors of Francisella tularensis in PortugalPublication . Carvalho, C.L.; Zé-Zé, Líbia; Duarte, E.L.; Núncio, M.S.; Carvalho, I.L.
- Tularaemia: a challenging zoonosisPublication . Carvalho, C.L.; Lopes de Carvalho, I.; Zé-Zé, Líbia; Núncio, M.S.; Duarte, E.L.In recent years, several emerging zoonotic vector-borne infections with potential impact on human health have been identified in Europe, including tularaemia, caused by Francisella tularensis. This remarkable pathogen, one of the most virulent microorganisms currently known, has been detected in increasingly new settings and in a wide range of wild species, including lagomorphs, rodents, carnivores, fish and invertebrate arthropods. Also, a renewed concern has arisen with regard to F. tularensis: its potential use by bioterrorists. Based on the information published concerning the latest outbreaks, the aim of this paper is to review the main features of the agent, its biology, immunology and epidemiology. Moreover, special focus will be given to zoonotic aspects of the disease, as tularaemia outbreaks in human populations have been frequently associated with disease in animals.