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Abstract
Recent research activities have provided new insights in vitamin D metabolism in various conditions. Furthermore, substantial progress has been made in the analysis of vitamin D metabolites and related biomarkers, such as vitamin D binding protein. Liquid chromatography tandem mass spectrometric (LC-MS/MS) methods are capable of accurately measuring multiple vitamin D metabolites in parallel. Nevertheless, only 25(OH)D and the biologically active form 1,25(OH)2D are routinely measured in clinical practice. While 25(OH)D remains the analyte of choice for the diagnosis of vitamin D deficiency, 1,25(OH)2D is only recommended in a few conditions with a dysregulated D metabolism. 24,25(OH)2D, free and bioavailable 25(OH)D, and the vitamin D metabolite ratio (VMR) have shown promising results, but technical pitfalls in their quantification, limited clinical data and the lack of reference values, impede their use in clinical practice. LC-MS/MS is the preferred method for the measurement of all vitamin D related analytes as it offers high sensitivity and specificity. In particular, 25(OH)D and 24,25(OH)2D can accurately be measured with this technology. When interpreted together, they seem to provide a functional measure of vitamin D metabolism beyond the analysis of 25(OH)D alone. The determination of VDBP, free and bioavailable 25(OH)D is compromised by unresolved analytical issues, lacking reference intervals and insufficient clinical data. Therefore, future research activities should focus on analytical standardization and exploration of their clinical value. This review provides an overview on established and new vitamin D related biomarkers including their pathophysiological role, preanalytical and analytical aspects, expected values, indications and influencing conditions.
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Affiliation(s)
- N Alonso
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - S Zelzer
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - G Eibinger
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - M Herrmann
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria.
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Üllen A, Nusshold C, Glasnov T, Saf R, Cantillo D, Eibinger G, Reicher H, Fauler G, Bernhart E, Hallstrom S, Kogelnik N, Zangger K, Oliver Kappe C, Malle E, Sattler W. Covalent adduct formation between the plasmalogen-derived modification product 2-chlorohexadecanal and phloretin. Biochem Pharmacol 2015; 93:470-81. [PMID: 25576489 PMCID: PMC4321883 DOI: 10.1016/j.bcp.2014.12.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/23/2014] [Accepted: 12/24/2014] [Indexed: 12/02/2022]
Abstract
Hypochlorous acid added as reagent or generated by the myeloperoxidase (MPO)-H2O2-Cl− system oxidatively modifies brain ether-phospholipids (plasmalogens). This reaction generates a sn2-acyl-lysophospholipid and chlorinated fatty aldehydes. 2-Chlorohexadecanal (2-ClHDA), a prototypic member of chlorinated long-chain fatty aldehydes, has potent neurotoxic potential by inflicting blood–brain barrier (BBB) damage. During earlier studies we could show that the dihydrochalcone-type polyphenol phloretin attenuated 2-ClHDA-induced BBB dysfunction. To clarify the underlying mechanism(s) we now investigated the possibility of covalent adduct formation between 2-ClHDA and phloretin. Coincubation of 2-ClHDA and phloretin in phosphatidylcholine liposomes revealed a half-life of 2-ClHDA of approx. 120 min, decaying at a rate of 5.9 × 10−3 min−1. NMR studies and enthalpy calculations suggested that 2-ClHDA-phloretin adduct formation occurs via electrophilic aromatic substitution followed by hemiacetal formation on the A-ring of phloretin. Adduct characterization by high-resolution mass spectroscopy confirmed these results. In contrast to 2-ClHDA, the covalent 2-ClHDA-phloretin adduct was without adverse effects on MTT reduction (an indicator for metabolic activity), cellular adenine nucleotide content, and barrier function of brain microvascular endothelial cells (BMVEC). Of note, 2-ClHDA-phloretin adduct formation was also observed in BMVEC cultures. Intraperitoneal application and subsequent GC–MS analysis of brain lipid extracts revealed that phloretin is able to penetrate the BBB of C57BL/6J mice. Data of the present study indicate that phloretin scavenges 2-ClHDA, thereby attenuating 2-ClHDA-mediated brain endothelial cell dysfunction. We here identify a detoxification pathway for a prototypic chlorinated fatty aldehyde (generated via the MPO axis) that compromises BBB function in vitro and in vivo.
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Affiliation(s)
- Andreas Üllen
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Christoph Nusshold
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Toma Glasnov
- Christian Doppler Laboratory for Flow Chemistry, Institute of Chemistry, University of Graz, Graz, Austria
| | - Robert Saf
- Institute of Chemistry and Technology of Materials, Graz University of Technology, Graz, Austria
| | - David Cantillo
- Institute of Chemistry, University of Graz, Graz, Austria
| | - Gerald Eibinger
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Helga Reicher
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Günter Fauler
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Eva Bernhart
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Seth Hallstrom
- Institute of Physiological Chemistry, Medical University of Graz, Graz, Austria
| | - Nora Kogelnik
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Klaus Zangger
- Institute of Chemistry, University of Graz, Graz, Austria
| | - C Oliver Kappe
- Institute of Chemistry, University of Graz, Graz, Austria
| | - Ernst Malle
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Wolfgang Sattler
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.
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Eibinger G, Fauler G, Bernhart E, Frank S, Hammer A, Wintersperger A, Eder H, Heinemann A, Mischel PS, Malle E, Sattler W. On the role of 25-hydroxycholesterol synthesis by glioblastoma cell lines. Implications for chemotactic monocyte recruitment. Exp Cell Res 2013; 319:1828-1838. [PMID: 23541792 DOI: 10.1016/j.yexcr.2013.03.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 03/18/2013] [Accepted: 03/20/2013] [Indexed: 12/21/2022]
Abstract
Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor and is invariably fatal to affected patients. Oxysterols belong to a class of bioactive lipids that are implicated in neurological disease and are associated with various types of cancer. Here, we investigated expression and transcriptional regulation of cholesterol 25-hydroxylase (CH25H) in human U87MG and GM133 glioblastoma cell lines. We demonstrate that in both cell lines transcription and translation of CH25H are increased in response to TNFα and IL1β. In parallel, both cell lines upregulate 25-hydroxycholesterol (25-OHC) synthesis and secretion to levels comparable to bone marrow-derived mouse macrophages under inflammatory conditions. To determine whether 25-OHC acts as chemoattractant for tumor-associated macrophages, the human THP-1 monoblastic leukemia cell line was treated with varying amounts of the oxysterol. Experiments revealed that 25-OHC and lipid extracts isolated from GM133-conditioned medium (containing 7-fold higher 25-OHC concentrations than U87MG medium) induce chemotactic migration of THP-1 cells. Of note, 25-OHC also induced the migration of primary human peripheral blood monocytes. In response to exogenously added 25-OHC, THP-1 cells reorganized intermediate filament-associated vimentin to more cortical and polarized structures. Chemotactic migration of monocytes in response to 25-OHC was pertussis toxin-sensitive, indicating the involvement of G protein-coupled receptors. Using RNA interference we demonstrated that G protein-coupled receptor 183 (EBI2) contributes to 25-OHC-mediated chemotactic migration of THP-1 cells. These in vitro data indicate that GBM-derived and secreted 25-OHC may be involved in the recruitment of immune-competent cells to a tumor via EBI2.
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Affiliation(s)
- Gerald Eibinger
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | - Günter Fauler
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz 8010, Austria
| | - Eva Bernhart
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | - Sasa Frank
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | - Astrid Hammer
- Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz 8010, Austria
| | - Andrea Wintersperger
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | - Hans Eder
- Department of Neurosurgery, Medical University of Graz, Graz 8010, Austria
| | - Akos Heinemann
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz 8010, Austria
| | - Paul S Mischel
- Ludwig Institute for Cancer Research, La Jolla, California, CA 92093, USA
| | - Ernst Malle
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | - Wolfgang Sattler
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria.
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Waltl S, Patankar JV, Fauler G, Nusshold C, Ullen A, Eibinger G, Wintersperger A, Kratky D, Malle E, Sattler W. 25-Hydroxycholesterol regulates cholesterol homeostasis in the murine CATH.a neuronal cell line. Neurosci Lett 2013; 539:16-21. [PMID: 23347841 PMCID: PMC3610018 DOI: 10.1016/j.neulet.2013.01.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 01/03/2013] [Accepted: 01/08/2013] [Indexed: 12/20/2022]
Abstract
Aberrant oxysterol biosynthesis is implicated in the pathogenesis of neurodegenerative diseases. During the present study we have investigated the effects of exogenously added 25-hydroxycholesterol (25-HC) on transcription of cholesterol biosynthetic genes, sterol-regulatory element binding protein (SREBP) processing and cholesterol biosynthesis in the murine CATH.a neuronal cell line. A single i.p. injection of lipopolysaccharide resulted in robust induction of cholesterol 25-hydroxylase mRNA and protein levels in brains of treated mice. In vitro, 25-HC upregulated the transcription of ATP-binding cassette transporter A1 (ABCA1) and (to a lesser extent) apolipoprotein E (apoE) in CATH.a neurons. Cholesterol biosynthetic gene expression (squalene synthase, HMG-CoA synthase, HMG-CoA reductase, and SREBP2) was downregulated by 25-HC. 25-HC also significantly attenuated proteolytic processing of SREBP2. Finally, 25-HC downregulated cholesterol biosynthesis in CATH.a neurons. Our results demonstrate that 25-HC is a potent effector oxysterol of neuronal cholesterol homeostasis.
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Affiliation(s)
- Sabine Waltl
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
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