Browsing by Author "Knigge, Thomas"
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- Developmental immunotoxicology: What underlies the critical windows of exposure?Publication . Moreira, Catarina; Paiola, Matthieu; Duflot, Aurelie; del Pozo, Raquel; Carla Piazzon, M.; Fouz, Belen; Varo, Inma; Sitja-Bobadilla, Ariadna; Knigge, Thomas; Pinto, Patricia IS; Monsinjon, TiphaineEndocrine disruptors in general and oestrogenic compounds in particular have been widely investigated in view of their effects on several physiological processes and, therefore, their ecotoxicologic relevance. The modulation of the immune system by oestrogens has increasingly sparked interest in the research community, that previously had been mainly centered on the reproductive effects of these hormones. In fact, since the industrialization an increasing variety of endocrine disruptors, such as oestrogenic endocrine disruptors, are retrieved in the environment. These oestrogenic endocrine disrupting chemicals (EEDCs) have also been suggested to increase the prevalence of autoimmune diseases and cancer. With regard to the high degree of similarities in the immune system of jawed vertebrates as well as the conserved immunomodulatory roles of oestrogen, environmental EEDCs possibly have the capacity to alter immune system functions of teleost fish, which may impair their capacity to fight infectious diseases and eventually may contribute, together with overfishing, to wild stock losses. Importantly, the most deleterious effects of EEDCs, both in mammals and teleosts, appear to arise when the exposure occurs during specific periods of the immune system ontogenesis, commonly referred as critical windows of exposure. However, in mammals and especially in teleost fish, these stages of the immune system development as well as the EEDC-action remain to be fully identified and characterised. The concept and the importance of developmental immunotoxicity is presented by addressing the mechanisms of oestrogenic regulation and the mode of action of EEDCs from an immunological perspective. Emphasis is given to the critical windows of development of the immune system during which EEDCs may alter the immune system development and function with long-term consequences on immunocompetence. Results from different classes of vertebrates are compiled, highlighting studies on teleost fish and their relevance for the human immune system. Additionally, new results on the effects of environmentally relevant concentration of exogenous estradiol exposure during European sea bass (Dicentrarchus labrax) development will be presented with regard to oestrogen's ability to trigger effects on immunocompetence, contributing to fill the gaps on vertebrate immunotoxicology.
- Evolutionary history and functional characterization of duplicated G protein-coupled estrogen receptors in European sea bassPublication . Zapater, Cinta; Moreira, Catarina; Knigge, Thomas; Monsinjon, Tiphaine; Gómez, Ana; Pinto, Patricia I. S.Across vertebrates, the numerous estrogenic functions are mainly mediated by nuclear and membrane receptors, including the G protein-coupled estrogen receptor (GPER) that has been mostly associated with rapid non-genomic responses. Although Gper-mediated signalling has been characterized in only few fish species, Gpers in fish appear to present more mechanistic functionalities as those of mammals due to additional gene duplicates. In this study, we ran a thorough investigation of the fish Gper evolutionary history in light of available genomes, we carried out the functional characterization of the two gper gene duplicates of European sea bass (Dicentrarchus labrax) using luciferase reporter gene transactivation assays, validated it with natural and synthetic estrogen agonists/antagonists and applied it to other chemicals of aquaculture and ecotoxicological interest. Phylogenetic and synteny analyses of fish gper1 and gper1-like genes suggest their duplication may have not resulted from the teleost-specific whole genome duplication. We confirmed that both sbsGper isoforms activate the cAMP signalling pathway and respond differentially to distinct estrogenic compounds. Therefore, as observed for nuclear estrogen receptors, both sbsGpers duplicates retain estrogenic activity although they differ in their specificity and potency (Gper1 being more potent and more specific than Gper1-like), suggesting a more conserved role for Gper1 than for Gper1-like. In addition, Gpers were able to respond to estrogenic environmental pollutants known to interfere with estrogen signalling, such as the phytoestrogen genistein and the anti-depressant fluoxetine, a point that can be taken into account in aquatic environment pollution screenings and chemical risk assessment, complementing previous assays for sea bass nuclear estrogen receptors.
- Oestrogen receptor distribution related to functional thymus anatomy of the European sea bass, Dicentrarchus labraxPublication . Paiola, Matthieu; Knigge, Thomas; Picchietti, Simona; Duflot, Aurelie; Guerra, Laura; Pinto, Patricia IS; Scapigliati, Giuseppe; Monsinjon, TiphaineIn jawed vertebrates, the crosstalk between immune and endocrine system as well as many fundamental mechanisms of T cell development are evolutionary conserved. Oestrogens affect mammalian thymic function and plasticity, but the mechanisms of action and the oestrogen receptors involved remain unclear. To corroborate the oestrogenic regulation of thymic function in teleosts and to identify the implicated oestrogen receptor subtypes, we examined the distribution of nuclear and membrane oestrogen receptors within the thymus of the European Sea bass, Dicentrarchus labrax, in relation to its morpho-functional organisation. Immunohistological analysis specified thymus histology and organisation in teleosts and described, for the first time, Hassall's corpuscle like structures in the medulla of sea bass. All oestrogen receptors were expressed at the transcript and protein level, both in T cells and in stromal cells belonging to specific functional areas. These observations suggest complex regulatory actions of oestrogen on thymic function, notably through the stromal microenvironment, comprising both, genomic and non-genomic pathways that are likely to affect T cell maturation and trafficking processes. Comparison with birds, rodents and humans supports the thymic localization of oestrogen receptors and suggests that oestrogens modulate T cell maturation in all gnathostomes. (C) 2017 Elsevier Ltd. All rights reserved.
- Oestrogen, an evolutionary conserved regulator of T cell differentiation and immune tolerance in jawed vertebrates?Publication . Paiola, Matthieu; Knigge, Thomas; Duflot, Aurélie; Pinto, Patricia IS; Farcy, Emilie; Monsinjon, TiphaineIn teleosts, as in mammals, the immune system is tightly regulated by sexual steroid hormones, such as oestrogens. We investigated the effects of 17β-oestradiol on the expression of several genes related to T cell development and resulting T cell subpopulations in sea bass, Dicentrarchus labrax, for a primary lymphoid organ, the thymus, and two secondary lymphoid organs, the head-kidney and the spleen. In parallel, the oxidative burst capacity was assessed in leucocytes of the secondary lymphoid organs. Apoptosis- and proliferation-related genes, indicative of B and T cell clonal selection and lymphoid progenitor activity, were not affected by elevated oestrogen-levels. Sex-related oestrogen-responsiveness in T cell and antigen-presenting cell markers was observed, the expression of which was differentially induced by oestrogen-exposure in the three lymphoid organs. Remarkably, in the spleen, oestrogen increased regulatory T cell-related gene expression was associated with a decrease in oxidative burst capacity. To the best of our knowledge, this study indicates for the first time that physiological levels of oestrogen are likely to promote immune tolerance by modulating thymic function (i.e., T cell development and output) and peripheral T cells in teleosts, similar to previously reported oestrogenic effects in mammals.
- Prepubertal gonad investment modulates thymus function: evidence in a teleost fishPublication . Paiola, Matthieu; Moreira, Catarina; Hétru, Julie; Duflot, Aurélie; Pinto, Patrícia; Scapigliati, Giuseppe; Knigge, Thomas; Monsinjon, TiphaineThymus plasticity following gonadectomy or sex hormone replacement has long since exemplified sex hormone effects on the immune system in mammals and, to a lesser extent, in 'lower vertebrates', including amphibians and fish. Nevertheless, the underlying physiological significances as well as the ontogenetic establishment of this crosstalk remain largely unknown. Here, we used a teleost fish, the European sea bass, Dicentrarchus labrax, to investigate: (1) whether the regulation of thymus plasticity relies on resource trade-off with somatic growth and reproductive investment and (2) if the gonad-thymus interaction takes place during gonadal differentiation and development. Because gonadal development and, supposedly, thymus function in sea bass depend on environmental changes associated with the winter season, we evaluated thymus changes (foxn1 expression, and thymocyte and T cell content) in juvenile D. labrax raised for 1 year under either constant or fluctuating photoperiod and temperature. Importantly, in both conditions, intensive gonadal development following sex differentiation coincided with a halt of thymus growth, while somatic growth continued. To the best of our knowledge, this is the first study showing that gonadal development during prepuberty regulates thymus plasticity. This finding may provide an explanation for the initiation of the thymus involution related to ageing in mammals. Comparing fixed and variable environmental conditions, our work also demonstrates that the extent of the effects on the thymus, which are related to reproduction, depend on ecophysiological conditions, rather than being directly related to sexual maturity and sex hormone levels.
- Proteomic changes in the extracellular environment of sea bass thymocytes exposed to 17α-ethinylestradiol in vitroPublication . Moreira, Catarina; Hétru, Julie; Paiola, Matthieu; Duflot, Aurélie; Chan, Philippe; Vaudry, David; Monsinjon, Tiphaine; Knigge, Thomas; Pinto, Patricia ISThe thymus is an important immune organ providing the necessary microenvironment for the development of a diverse, self-tolerant T cell repertoire, which is selected to allow for the recognition of foreign antigens while avoiding self-reactivity. Thymus function and activity are known to be regulated by sex steroid hormones, such as oestrogen, leading to sexual dimorphisms in immunocompetence between males and females. The oestrogenic modulation of the thymic function provides a potential target for environmental oestrogens, such as 17α-ethynylestradiol (EE2), to interfere with the cross-talk between the endocrine and the immune system. Oestrogen receptors have been identified on thymocytes and the thymic microenvironment, but it is unclear how oestrogens regulate thymic epithelial and T cell communication including paracrine signalling. Much less is known regarding intrathymic signalling in fish. Secretomics allows for the analysis of complex mixtures of immunomodulatory signalling factors secreted by T cells. Thus, in the present study, isolated thymocytes of the European sea bass, Dicentrarchus labrax, were exposed in vitro to 30 nM EE2 for 4 h and the T cell-secretome (i.e., extracellular proteome) was analysed by quantitative label-free mass-spectrometry. Progenesis revealed a total of 111 proteins differentially displayed between EE2-treated and control thymocytes at an α-level of 5% and a 1.3- fold change cut off (n = 5-6). The EE2-treatment significantly decreased the level of 90 proteins. Gene ontology revealed the proteasome to be the most impacted pathway. In contrast, the abundance of 21 proteins was significantly increased, with cathepsins showing the highest level of induction. However, no particular molecular pathway was significantly altered for these upregulated proteins. To the best of our knowledge, this work represents the first study of the secretome of the fish thymus exposed to the environmental oestrogen EE2, highlighting the impact on putative signalling pathways linked to immune surveillance, which may be of crucial importance for fish health and defence against pathogens.
- The influence of 17β-oestradiol on lymphopoiesis and immune system ontogenesis in juvenile sea bass, Dicentrarchus labraxPublication . Moreira, Catarina; Paiola, Matthieu; Duflot, Aurélie; Varó, Inma; Sitjà-Bobadilla, Ariadna; Knigge, Thomas; Pinto, P; Monsinjon, TiphaineThe female sex steroid 17β-oestradiol (E2) is involved in the regulation of numerous physiological functions, including the immune system development and performance. The role of oestrogens during ontogenesis is, however, not well studied. In rodents and fish, thymus maturation appears to be oestrogen-dependent. Never theless, little is known about the function of oestrogen in immune system development. To further the under standing of the role of oestrogens in fish immune system ontogenesis, fingerlings of European sea bass (Dicentrarchus labrax) were exposed for 30 days to 20 ng E2⋅L− 1 , at two ages tightly related to thymic maturation, i.e., 60 or 90 days post hatch (dph). The expression of nuclear and membrane oestrogen receptors was measured in the thymus and spleen, and the expression of several T cell-related gene markers was studied in both immune organs, as well as in the liver. Waterborne E2-exposure at 20.2 ± 2.1 (S.E.) ng⋅L− 1 was confirmed by radioimmunoassay, leading to significantly higher E2-contents in the liver of exposed fish. The majority of gene markers presented age-dependent dynamics in at least one of the organs, confirming thymus maturation, but also suggesting a critical ontogenetic window for the implementation of liver resident γδ and αβ T cells. The oestrogen receptors, however, remained unchanged over the age and treatment comparisons with the exception of esr2b, which was modulated by E2 in the younger cohort and increased its expression with age in the thymus of the older cohort, as did the membrane oestrogen receptor gpera. These results confirm that oestrogen-signalling is involved in thymus maturation in European sea bass, as it is in mammals. This suggests that esr2b and gpera play key roles during thymus ontogenesis, particularly during medulla maturation. In contrast, the spleen expressed low or non-detectable levels of oestrogen receptors. The E2-exposure decreased the expression of tcrγ in the liver in the cohort exposed from 93 to 122 dph, but not the expression of any other immune-related gene analysed. These results indicate that the proliferation/migration of these innate-like T cell populations is estrogensensitive. In regard to the apparent prominent role of oestrogen-signalling in the late thymus maturation stage, the thymic differentiation of the corresponding subpopulations of T cells might be regulated by oestrogen. To the best of our knowledge, this is the first study investigating the dynamics of both nuclear and membrane oestrogen receptors in specific immune organs in a teleost fish at very early stages of immune system development as well as to examine thymic function in sea bass after an exposure to E2 during ontogenesis.