Sondersammlungen

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    Regulation of Klotho production by mineralocorticoid receptor signaling in renal cell lines
    (2025) Kohm, Elena; Feger, Martina; Föller, Michael; Kohm, Elena; Department of Physiology, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany; Feger, Martina; Department of Physiology, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany; Yayama, Katsutoshi; Department of Physiology, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany; Yayama, Katsutoshi
    Through the mineralocorticoid receptor, aldosterone controls extracellular volume and arterial blood pressure by stimulating Na⁺ absorption and K⁺ secretion in epithelial cells of the kidney, colon, and several glands. Hyperaldosteronism promotes fibrosis and inflammation in epithelial and non-epithelial tissues, thereby favoring loss of kidney and heart function. Mineralocorticoid receptor blockade therefore gains relevance especially in renal and cardiac disease. Kidney-derived Klotho is a powerful anti-aging protein with anti-fibrosis and anti-inflammatory effects providing cardio- and nephroprotection. We wondered whether Klotho expression and production is influenced by mineralocorticoid receptor agonists and antagonists. Using four renal cell lines, Madin-Darby canine kidney (MDCK), normal rat kidney, subtype 52E (NRK-52E), human kidney 2 (HK2) cells, and primary renal proximal tubule epithelial cells (RPTECs), and the four most frequently prescribed mineralocorticoid receptor blockers, spironolactone, eplerenone, finerenone, and esaxerenone, we assessed Klotho gene expression by qRT-PCR and Klotho protein by Western blotting. Aldosterone and eplerenone did not significantly affect Klotho expression in either cell line. Spironolactone enhanced Klotho expression in MDCK and NRK-52E cells and downregulated Klotho in HK2 cells and RPTECs. Novel non-steroidal mineralocorticoid receptor antagonist finerenone downregulated Klotho expression in MDCK, NRK-52E, and low-dose finerenone in HK2 cells. To conclude, common mineralocorticoid receptor antagonists are characterized by highly diverse effects on Klotho in four renal cell lines. Further studies are needed to define the role of mineralocorticoid receptor blockade for Klotho production.
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    Tannic acid and ethacridine lactate attenuate markers of stress-induced intestinal barrier dysfunctions in murine small intestinal organoids
    (2025) Filipe Rosa, Louisa; Gonda, Steffen; Roese, Nadine; Bischoff, Stephan C.; Kwok, Hang Fai (Henry); Alaimo, Alessandro
    (1) Background: Tannacomp® is a drug consisting of tannin albuminate, a complex of tannic acid (TA) and ethacridine lactate (Eta) used for treating acute and traveler’s diarrhea. TA is thought to modulate gastrointestinal barrier function, but the underlying mechanisms and whether Eta has similar effects remains unclear. (2) Methods: to investigate the effects of TA and Eta on the intestinal barrier, stress responses were induced in murine intestinal organoids by lipopolysaccharide (LPS) exposure or withdrawal of growth factors from cell culture medium (GFRed). Further, organoids were exposed to either TA (0.01 mg/mL) or Eta (0.002 mg/mL) and markers of inflammatory response and gut barrier function were assessed. (3) Results: TA and Eta reduced several inflammatory markers such as interleukin 6, interleukin 1β, tumor necrosis factor α, and myeloid differentiation primary response 88 in stressed organoids. In addition, TA and Eta attenuated LPS- and GFRed-mediated gut barrier dysfunctions, with normalization of tight junction, adherent junction and mucin gene expression and reduction of Nod2- and matrix metalloproteinase 7-dependent activation of antimicrobial peptides. (4) Conclusions: our data show that TA and Eta modulate markers of inflammation and the intestinal barrier and suggest novel mechanisms of action of this drug that could broaden its treatment indications.