| 1. |
- Buse, Eberhard, et al.
(författare)
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The placenta in toxicology. Part I : Animal models in toxicology
- 2014
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Ingår i: Toxicologic pathology (Print). - : Sage Publications. - 0192-6233 .- 1533-1601. ; 42:2, s. 314-326
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Forskningsöversikt (refereegranskat)abstract
- The immune system represents a key defense mechanism against potential pathogens and adverse non-self materials. During pregnancy, the placenta is the point of contact between the maternal organism and non-self proteins of the fetal allograft and hence undoubtedly fulfils immune functions. In the placenta bacteria, foreign (non-self) proteins and proteins that might be introduced in toxicological studies or by medication are barred from reaching the progeny, and the maternal immune system is primed for acceptance of non-maternal fetal protein. Both immunologic protection of the fetus and acceptance of the fetus by the mother require effective mechanisms to prevent an immunologic fetomaternal conflict and to keep both organisms in balance. This is why the placenta requires toxicological consideration in view of its immune organ function. The following articles deal with placenta immune-, control-, and tolerance mechanisms in view of both fetal and maternal aspects. Furthermore, models for experimental access to placental immune function are addressed and the pathological evaluation is elucidated. "The Placenta as an Immune Organ and Its Relevance in Toxicological Studies" was subject of a continuing education course at the 2012 Society of Toxicologic Pathology meeting held in Boston, MA.
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| 2. |
- Cline, J Mark, et al.
(författare)
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The placenta in toxicology. Part III : Pathologic assessment of the placenta
- 2014
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Ingår i: Toxicologic pathology (Print). - : Sage Publications. - 0192-6233 .- 1533-1601. ; 42:2, s. 339-344
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Tidskriftsartikel (refereegranskat)abstract
- This short review is derived from the peer-reviewed literature and the experience and case materials of the authors. Brief illustrated summaries are presented on the gross and histologic normal anatomy of rodent and macaque placentas, including typical organ weights, with comments on differences from the human placenta. Common incidental findings, background lesions, and induced toxic lesions are addressed, and a recommended strategy for pathologic evaluation of placentas is provided.
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| 3. |
- Göhner, Claudia, et al.
(författare)
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The placenta in toxicology. Part IV : Battery of toxicological test systems based on human placenta
- 2014
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Ingår i: Toxicologic pathology (Print). - : Sage Publications. - 0192-6233 .- 1533-1601. ; 42:2, s. 345-351
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Tidskriftsartikel (refereegranskat)abstract
- This review summarizes the potential and also some limitations of using human placentas, or placental cells and structures for toxicology testing. The placenta contains a wide spectrum of cell types and tissues, such as trophoblast cells, immune cells, fibroblasts, stem cells, endothelial cells, vessels, glands, membranes, and many others. It may be expected that in many cases the relevance of results obtained from human placenta will be higher than those from animal models due to species specificity of metabolism and placental structure. For practical and economical reasons, we propose to apply a battery of sequential experiments for analysis of potential toxicants. This should start with using cell lines, followed by testing placenta tissue explants and isolated placenta cells, and finally by application of single and dual side ex vivo placenta perfusion. With each of these steps, the relative workload increases while the number of feasible repeats decreases. Simultaneously, the predictive power enhances by increasing similarity with in vivo human conditions. Toxic effects may be detected by performing proliferation, vitality and cell death assays, analysis of protein and hormone expression, immunohistochemistry or testing functionality of signaling pathways, gene expression, transport mechanisms, and so on. When toxic effects appear at any step, the subsequent assays may be cancelled. Such a system may be useful to reduce costs and increase specificity in testing questionable toxicants. Nonetheless, it requires further standardization and end point definitions for better comparability of results from different toxicants and to estimate the respective in vivo translatability and predictive value.
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| 4. |
- Svensson-Arvelund, Judit, 1982-, et al.
(författare)
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The placenta in toxicology. Part II : Systemic and local immune adaptations in pregnancy
- 2014
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Ingår i: Toxicologic pathology (Print). - : Sage Publications. - 0192-6233 .- 1533-1601. ; 42:2, s. 327-338
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Tidskriftsartikel (refereegranskat)abstract
- During pregnancy, the maternal immune system is challenged by the semiallogeneic fetus, which must be tolerated without compromising fetal or maternal health. This review updates the systemic and local immune changes taking place during human pregnancy, including some examples in rodents. Systemic changes are induced by contact of maternal blood with placental factors and include enhanced innate immunity with increased activation of granulocytes and nonclassical monocytes. Although a bias toward T helper (Th2) and regulatory T cell (Treg) immunity has been associated with healthy pregnancy, the relationship between different circulating Th cell subsets is not straightforward. Instead, these adaptations appear most evidently at the fetal-maternal interface, where for instance Tregs are enriched and promote fetal tolerance. Also innate immune cells, that is, natural killer cells and macrophages, are enriched, constituting the majority of decidual leukocytes. These cells not only contribute to immune regulation but also aid in establishing the placenta by promoting trophoblast recruitment and angiogenesis. Thus, proper interaction between leukocytes and placental trophoblasts is necessary for normal placentation and immune adaptation. Consequently, spontaneous maladaptation or interference of the immune system with toxic substances may be important contributing factors for the development of pregnancy complications such as preeclampsia, preterm labor, and recurrent miscarriages.
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