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"M. Merk"
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Synergistic Zinc(II) and Formate Doping of Perovskites: Thermal Phase Stabilization of α-FAPbI3 and Enhanced Photoluminescence Lifetime of FA0.8MA0.2PbI3 up to 3.7 µs
2024
Adding zinc (II) cations and formate anions improves the thermal phase stability of α-FAPbI3 materials, and the spin-coated thin films of such doped FAPbI3 (produced using MACl) show an increased emission lifetime of up to 3.7 μs on quartz (for FA0.8MA0.2PbI3). This work investigates the effects of zinc and formate on the phase stability and time-resolved photoluminescence of FAPbI3 perovskites for solar cell applications. Perovskite samples with varying concentrations of zinc and formate were made by incorporating different amounts of zinc formate and zinc iodide and were characterized with XRD. Doping levels of 1.7% Zn(II) and 1.0% formate (relative to Pb) seem optimal. The thermal phase stability of the doped perovskite powders (FAPbI3) and thin films (FA0.8MA0.2PbI3) was assessed. XRD of the thin films after 6 months shows only the alpha-phase. The time-resolved photoluminescence spectroscopy of the doped spin-coated perovskite samples (FA0.8MA0.2PbI3 produced using MACl) is reported. The results show that synergy between an anionic and a cationic dopant can take place, making the perovskite thermally more phase-stable (not converting to the yellow delta-phase) with a longer charge carrier lifetime. In order to produce good thin films by spin coating, the use of MACl was essential.
Journal Article
Human lung carcinomas synthesize immunoregulatory glucocorticoids
2023
The need for new options in lung cancer treatment inevitably leads back to basic research. The tumor itself and the tumor environment especially the interaction with the immune system need to be better understood to develop targeted therapies. In the context of lung cancer glucocorticoids (GC) are mainly known as a combination drug to attenuate side-effects of chemotherapies. However, endogenous extra-adrenal GC have been shown to substantially regulate local immune responses within various tissues, including the lung. In this study we investigated whether primary lung tumors have maintained the capacity to synthesize GC and may thereby regulate anti-tumor immune responses. We show that several non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC) cell lines express key steroidogenic enzymes and synthesize bioactive GC under steady state conditions. We also show that tumor-derived GC can inhibit splenic T cell activation, thus demonstrating their immunoregulatory potential. Moreover, steroidogenic enzymes were detected by quantitative RT-PCR and immunohistochemistry in tissue sections of different human lung tumors, further strengthening the idea that human lung carcinomas regulate their microenvironment by releasing immunoregulatory GC, which potentially contributes to immune evasion and treatment resistance.
Journal Article
Regulation of Tissue Immune Responses by Local Glucocorticoids at Epithelial Barriers and Their Impact on Interorgan Crosstalk
2021
The anti-inflammatory role of extra-adrenal glucocorticoid (GC) synthesis at epithelial barriers is of increasing interest with regard to the search for alternatives to synthetic corticosteroids in the therapy of inflammatory disorders. Despite being very effective in many situations the use of synthetic corticosteroids is often controversial, as exemplified in the treatment of influenza patients and only recently in the current COVID-19 pandemic. Exploring the regulatory capacity of locally produced GCs in balancing immune responses in barrier tissues and in pathogenic disorders that lead to symptoms in multiple organs, could provide new perspectives for drug development. Intestine, skin and lung represent the first contact zones between potentially harmful pathogens or substances and the body, and are therefore important sites of immunoregulatory mechanisms. Here, we review the role of locally produced GCs in the regulation of type 2 immune responses, like asthma, atopic dermatitis and ulcerative colitis, as well as type 1 and type 3 infectious, inflammatory and autoimmune diseases, like influenza infection, psoriasis and Crohn’s disease. In particular, we focus on the role of locally produced GCs in the interorgan communication, referred to as gut-skin axis, gut-lung axis or lung-skin axis, all of which are interconnected in the pathogenic crosstalk atopic march.
Journal Article
Local glucocorticoid synthesis regulates house dust mite-induced airway hypersensitivity in mice
by
Wiedmann, Alice
,
Brunner, Thomas
,
Merk, Verena M.
in
11β-Hydroxysteroid dehydrogenase
,
11β-hydroxysteroid dehydrogenase 1
,
airway hypersensitivity
2023
BackgroundExtra-adrenal glucocorticoid (GC) synthesis at epithelial barriers, such as skin and intestine, has been shown to be important in the local regulation of inflammation. However, the role of local GC synthesis in the lung is less well studied. Based on previous studies and the uncontentious efficacy of corticosteroid therapy in asthma patients, we here investigated the role of 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1/ Hsd11b1 )-dependent local GC reactivation in the regulation of allergic airway inflammation.MethodsAirway inflammation in Hsd11b1-deficient and C57BL/6 wild type mice was analyzed after injection of lipopolysaccharide (LPS) and anti-CD3 antibody, and in acute and chronic models of airway hypersensitivity induced by house dust mite (HDM) extract. The role of 11β-HSD1 in normal and inflammatory conditions was assessed by high dimensional flow cytometry, histological staining, RT-qPCR analysis, ex vivo tissue cultures, GC-bioassays and protein detection by ELISA and immunoblotting.ResultsHere we show that lung tissue from Hsd11b1-deficient mice synthesized significantly less GC ex vivo compared with wild type animals in response to immune cell stimulation. We further observed a drastically aggravated phenotype in Hsd11b1-deficient mice treated with HDM extract compared to wild type animals. Besides eosinophilic infiltration, Hsd11b1-deficient mice exhibited aggravated neutrophilic infiltration caused by a strong Th17-type immune response.ConclusionWe propose an important role of 11β-HSD1 and local GC in regulating Th17-type rather than Th2-type immune responses in HDM-induced airway hypersensitivity in mice by potentially controlling Toll-like receptor 4 (TLR4) signaling and cytokine/chemokine secretion by airway epithelial cells.
Journal Article
Wild Harvesting vs. Cultivation: Total Petasin Content in Petasites hybridus Rhizome Extracts Determines Spasmolytic Effects
by
Boonen, Georg
,
Merk, Verena M.
,
Drewe, Jürgen
in
Accreditation
,
Animal welfare
,
Chromatography
2025
The use of herbal medicines containing Petasites hybridus extracts has a long history in the treatment of various ailments. The observed effects are primarily due to pharmacologically active compounds such as petasin, isopetasin, and neopetasin. In evidence-based phytotherapy, extracts from leaves and rhizomes are applied for different indications. While leaf extracts are administered to treat allergic rhinitis symptoms, rhizome extracts are utilized among others in the management of gastrointestinal spasms and migraines. The quality and source of plants are critical for producing authorized herbal medicinal products. Although the preparation of P. hybridus leaf extracts from cultivated plant material is already established, the rhizomes used for preparing extracts are still derived from commercial wild collections. However, switching to cultivation is desirable to ensure consistent quality and availability. For regulatory purposes, comparative pharmacological studies are needed to assess the bioactivity of plant material from different sources. Therefore, this study analyzed rhizome extracts from wild harvesting and cultivation for their petasin composition (i.e., isopetasin, neopetasin, petasin) and spasmolytic effects on Ca2+-dependent precontracted guinea pig ileum ex vivo. The results confirm petasins as active compounds of P. hybridus rhizome extracts. Moreover, they demonstrate that the total content of petasins determines the spasmolytic effects, regardless of the individual composition of the different petasins. No significant differences in efficacy were found between cultivated and wild-collected rhizomes, demonstrating that cultivated material is a reliable, consistent, and sustainable alternative for P. hybridus rhizome extract production.
Journal Article
Immune escape of colorectal tumours via local LRH‐1/Cyp11b1‐mediated synthesis of immunosuppressive glucocorticoids
by
Menche, Constantin
,
Urwyler, Corinne
,
Karamitopoulou, Eva
in
Adrenal glands
,
Animals
,
Antigens
2023
Control of tumour development and growth by the immune system critically defines patient fate and survival. What regulates the escape of colorectal tumours from destruction by the immune system remains currently unclear. Here, we investigated the role of intestinal synthesis of glucocorticoids in the tumour development during an inflammation‐induced mouse model of colorectal cancer. We demonstrate that the local synthesis of immunoregulatory glucocorticoids has dual roles in the regulation of intestinal inflammation and tumour development. In the inflammation phase, LRH‐1/Nr5A2‐regulated and Cyp11b1‐mediated intestinal glucocorticoid synthesis prevents tumour development and growth. In established tumours, however, tumour‐autonomous Cyp11b1‐mediated glucocorticoid synthesis suppresses anti‐tumour immune responses and promotes immune escape. Transplantation of glucocorticoid synthesis‐proficient colorectal tumour organoids into immunocompetent recipient mice resulted in rapid tumour growth, whereas transplantation of Cyp11b1‐deleted and glucocorticoid synthesis‐deficient tumour organoids was characterized by reduced tumour growth and increased immune cell infiltration. In human colorectal tumours, high expression of steroidogenic enzymes correlated with the expression of other immune checkpoints and suppressive cytokines, and negatively correlated with overall patients' survival. Thus, LRH‐1‐regulated tumour‐specific glucocorticoid synthesis contributes to tumour immune escape and represents a novel potential therapeutic target. Extra‐adrenal glucocorticoid synthesis in the intestinal epithelium controls intestinal homeostasis, inflammation and colitis‐associated tumour development in a Liver Receptor Homolog‐1 (LRH‐1/NR5A2)‐regulated manner. LRH‐1 drives proliferation and tumour‐autonomous glucocorticoid synthesis, which suppresses anti‐tumour immune responses and promotes immune escape.
Journal Article
St. John's Wort for Depression: From Neurotransmitters to Membrane Plasticity
by
Boonen, Georg
,
Butterweck, Veronika
,
Merk, Verena M
in
Animals
,
Antidepressants
,
Antidepressive Agents - pharmacology
2025
Depression is a multifactorial disorder shaped by genetic, psychosocial, and biological influences, with hypotheses ranging from monoamine deficiency and neuroplasticity deficits to inflammation and stress-induced dysregulation. St. John's wort (
L.) has long been used as an herbal antidepressant and is supported by clinical evidence for efficacy and safety in mild-to-moderate depression. While its multimodal mechanisms have been linked to neurotransmitter reuptake inhibition, neuroendocrine regulation, and modulation of neuroplasticity, recent findings suggest an additional role at the membrane level. Emerging lipidomic studies highlight that Ze 117, a low-hyperforin
extract, counteracts stress- and glucocorticoid-induced increases in membrane fluidity by modulating lipid composition and cholesterol metabolism. These effects normalize receptor mobility and signal transduction, particularly of β1-adrenoceptors, and modulate glycerophospholipid metabolism in both cellular and animal models. Such membrane-stabilizing properties may represent a novel mechanistic pathway complementing classical neurochemical actions. This review revisits the mechanisms of St. John's wort with a special focus on its impact on membrane lipids, positioning lipidomics as a promising tool for elucidating antidepressant activity. These insights may open avenues toward personalized therapeutic strategies in depression.
Journal Article
Extra-adrenal glucocorticoid synthesis at epithelial barriers
by
Phan Truong San
,
Brunner, Thomas
,
Merk, Verena M
in
Anti-inflammatory agents
,
Gases
,
Glucocorticoids
2019
Epithelial barriers play an important role in the exchange of nutrients, gases, and other signals between our body and the outside world. However, they protect it also from invasion by potential pathogens. Defective epithelial barriers and associated overshooting immune responses are the basis of many different inflammatory disorders of the skin, the lung, and the intestinal mucosa. The anti-inflammatory activity of glucocorticoids has been efficiently used for the treatment of these diseases. Interestingly, epithelia in these tissues are also a rich source of endogenous glucocorticoids, suggesting that local glucocorticoid synthesis is part of a tissue-specific regulatory circuit. In this review, we summarize current knowledge about the extra-adrenal glucocorticoid synthesis at the epithelial barriers of the intestine, lung and the skin, and discuss their relevance in the pathogenesis of inflammatory diseases and as therapeutic targets.
Journal Article
Synergistic Zinc and Formate Doping of Perovskites: Thermal Phase Stabilization of α-FAPbIsub.3 and Enhanced Photoluminescence Lifetime of FAsub.0.8MAsub.0.2PbIsub.3 up to 3.7 µs
2024
Adding zinc (II) cations and formate anions improves the thermal phase stability of α-FAPbI[sub.3] materials, and the spin-coated thin films of such doped FAPbI[sub.3] (produced using MACl) show an increased emission lifetime of up to 3.7 μs on quartz (for FA[sub.0.8]MA[sub.0.2]PbI[sub.3]). This work investigates the effects of zinc and formate on the phase stability and time-resolved photoluminescence of FAPbI[sub.3] perovskites for solar cell applications. Perovskite samples with varying concentrations of zinc and formate were made by incorporating different amounts of zinc formate and zinc iodide and were characterized with XRD. Doping levels of 1.7% Zn(II) and 1.0% formate (relative to Pb) seem optimal. The thermal phase stability of the doped perovskite powders (FAPbI[sub.3]) and thin films (FA[sub.0.8]MA[sub.0.2]PbI[sub.3]) was assessed. XRD of the thin films after 6 months shows only the alpha-phase. The time-resolved photoluminescence spectroscopy of the doped spin-coated perovskite samples (FA[sub.0.8]MA[sub.0.2]PbI[sub.3] produced using MACl) is reported. The results show that synergy between an anionic and a cationic dopant can take place, making the perovskite thermally more phase-stable (not converting to the yellow delta-phase) with a longer charge carrier lifetime. In order to produce good thin films by spin coating, the use of MACl was essential.
Journal Article