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Viitanen R, Virtanen H, Liljenbäck H, Moisio O, Li XG, Nicolini V, Richard M, Klein C, Nayak T, Jalkanen S, Roivainen A. [68Ga]Ga-DOTA-Siglec-9 Detects Pharmacodynamic Changes of FAP-Targeted IL2 Variant Immunotherapy in B16-FAP Melanoma Mice. Front Immunol 2022; 13:901693. [PMID: 35874707 PMCID: PMC9298541 DOI: 10.3389/fimmu.2022.901693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 06/14/2022] [Indexed: 11/29/2022] Open
Abstract
Vascular adhesion protein-1 (VAP-1) is an inflammation-inducible adhesion molecule, which supports contact between leukocytes and inflamed endothelium. There is evidence that VAP-1 is involved in the recruitment of leukocytes to melanoma tumors. Interleukin-2 (IL-2)-based immunotherapy is an efficient therapy that promotes immune system activity against cancers but is associated with toxicity. In the present study, we evaluated the feasibility of PET/CT imaging using the radiotracer [68Ga]Ga-DOTA-Siglec-9, which is targeted to VAP-1, to monitor pharmacodynamic effects of a novel FAP-IL2v immunocytokine (a genetically engineered variant of IL-2 fused with fibroblast activation protein) in the B16-FAP melanoma model. At 9 days after the inoculation of B16-FAP melanoma cells, mice were studied with [68Ga]Ga-DOTA-Siglec-9 PET/CT as a baseline measurement. Immediately after baseline imaging, mice were treated with FAP-IL2v or vehicle, and treatment was repeated 3 days later. Subsequent PET/CT imaging was performed 3, 5, and 7 days after baseline imaging. In addition to in vivo PET imaging, ex vivo autoradiography, histology, and immunofluorescence staining were performed on excised tumors. B16-FAP tumors were clearly detected with [68Ga]Ga-DOTA-Siglec-9 PET/CT during the follow-up period, without differences in tumor volume between FAP-IL2v-treated and vehicle-treated groups. Tumor-to-muscle uptake of [68Ga]Ga-DOTA-Siglec-9 was significantly higher in the FAP-IL2v-treated group than in the vehicle-treated group 7 days after baseline imaging, and this was confirmed by tumor autoradiography analysis. FAP-IL2v treatment did not affect VAP-1 expression on the tumor vasculature. However, FAP-IL2v treatment increased the number of CD8+ T cells and natural killer cells in tumors. The present study showed that [68Ga]Ga-DOTA-Siglec-9 can detect B16-FAP tumors and allows monitoring of FAP-IL2v treatment.
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Affiliation(s)
| | | | - Heidi Liljenbäck
- Turku PET Centre, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - Olli Moisio
- Turku PET Centre, University of Turku, Turku, Finland
| | - Xiang-Guo Li
- Turku PET Centre, University of Turku, Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, Turku, Finland
- Department of Chemistry, University of Turku, Turku, Finland
| | - Valeria Nicolini
- Roche Pharma Research and Early Development, Roche Innovation Center Zurich, Schlieren, Switzerland
| | - Marine Richard
- Roche Pharma Research and Early Development, Roche Innovation Center Zurich, Schlieren, Switzerland
| | - Christian Klein
- Roche Pharma Research and Early Development, Roche Innovation Center Zurich, Schlieren, Switzerland
| | - Tapan Nayak
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Sirpa Jalkanen
- InFLAMES Research Flagship Center, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Anne Roivainen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku Center for Disease Modeling, University of Turku, Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
- *Correspondence: Anne Roivainen,
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Mergemeier K, Galster F, Lehr M. HPLC-UV assay for the evaluation of inhibitors of plasma amine oxidase using crude bovine plasma. J Enzyme Inhib Med Chem 2019; 34:144-149. [PMID: 30427224 PMCID: PMC6237158 DOI: 10.1080/14756366.2018.1524890] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/04/2018] [Accepted: 09/13/2018] [Indexed: 11/21/2022] Open
Abstract
Recently, we have described a method for evaluation of plasma amine oxidase (PAO) inhibitors, which monitors the formation of 6-(5-phenyl-2H-tetrazol-2-yl)hexanal from the corresponding amine substrate by HPLC with UV-detection using purified bovine PAO. We now investigated, whether crude bovine plasma can be used as enzyme source in this assay instead of the purified enzyme. With the aid of specific inhibitors, it was ensured that there was no detectable activity of other important amine oxidases in the plasma, namely monoamine oxidase (MAO) A and B and diamine oxidase (DAO). For a series of ω-(5-phenyl-2H-tetrazol-2-yl)alkan-1-amine substrates similar conversion rates were measured for both the purified PAO and crude plasma. The inhibition values determined for the PAO inhibitor 2-(4-phenylphenyl)acetohydrazide (16) under different conditions also corresponded. Additionally, inhibition data of the known PAO inhibitor 2-amino-N-(3-phenylbenzyl)acetamide (17) and a newly synthesised meta-substituted derivative of 16 were determined, which together reflect the two-step inhibition mechanism of these covalent inhibitors.
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Affiliation(s)
- Kira Mergemeier
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Florian Galster
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Matthias Lehr
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
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3
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Abstract
Significance: Vascular adhesion protein-1 (VAP-1) is an ectoenzyme that oxidates primary amines in a reaction producing also hydrogen peroxide. VAP-1 on the blood vessel endothelium regulates leukocyte extravasation from the blood into tissues under physiological and pathological conditions. Recent Advances: Inhibition of VAP-1 by neutralizing antibodies and by several novel small-molecule enzyme inhibitors interferes with leukocyte trafficking and alleviates inflammation in many experimental models. Targeting of VAP-1 also shows beneficial effects in several other diseases, such as ischemia/reperfusion, fibrosis, and cancer. Moreover, soluble VAP-1 levels may serve as a new prognostic biomarker in selected diseases. Critical Issues: Understanding the contribution of the enzyme activity-independent and enzyme activity-dependent functions, which often appear to be mediated by the hydrogen peroxide production, in the VAP-1 biology will be crucial. Similarly, there is a pressing need to understand which of the VAP-1 functions are regulated through the modulation of leukocyte trafficking, and what is the role of VAP-1 synthesized in adipose and smooth muscle cells. Future Directions: The specificity and selectivity of new VAP-1 inhibitors, and their value in animal models under therapeutic settings need to be addressed. Results from several programs studying the therapeutic potential of VAP-1 inhibition, which now are in clinical trials, will reveal the relevance of this amine oxidase in humans.
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Affiliation(s)
- Marko Salmi
- 1 MediCity , Turku, Finland .,2 Institute of Biomedicine, University of Turku, Turku, Finland
| | - Sirpa Jalkanen
- 1 MediCity , Turku, Finland .,2 Institute of Biomedicine, University of Turku, Turku, Finland
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Mergemeier K, Lehr M. HPLC-UV assays for evaluation of inhibitors of mono and diamine oxidases using novel phenyltetrazolylalkanamine substrates. Anal Biochem 2018; 549:29-38. [PMID: 29550344 DOI: 10.1016/j.ab.2018.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/05/2018] [Accepted: 03/12/2018] [Indexed: 10/17/2022]
Abstract
Recently, we have described an HPLC-UV assay for the evaluation of inhibitors of plasma amine oxidase (PAO) using 6-(5-phenyl-2H-tetrazol-2-yl)hexan-1-amine (4) as a new type of substrate. Now we studied, whether this compound or homologues of it can also function as substrate for related amine oxidases, namely diamine oxidase (DAO), monoamine oxidase A (MAO A) and monoamine oxidase B (MAO B). Among these substances, 4 was converted by DAO with the highest rate. The best substrate for MAO A and B was 4-(5-phenyl-2H-tetrazol-2-yl)butan-1-amine (2). To validate the new assays, the inhibition values of known enzyme inhibitors were determined and the data were compared with those obtained with the substrate benzylamine, which is often used in amine oxidase assays. For the DAO inhibitor 2-(4-phenylphenyl)acetohydrazide an about 10fold lower IC50-value against DAO was obtained when benzylamine was applied instead of 4, indicating that 4 binds to the enzyme with higher affinity than benzylamine. The IC50-values of clorgiline and selegiline against MAO A and B, respectively, also decreased (two- and 30fold) replacing 2 by benzylamine. The discrepancies largely disappeared, when the enzymes were pre-incubated with the inhibitors for 15 min. This can be explained with the covalent inhibition mechanism of the inhibitors.
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Affiliation(s)
- Kira Mergemeier
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstrasse 48, 48149 Münster, Germany
| | - Matthias Lehr
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstrasse 48, 48149 Münster, Germany.
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Mapping the interaction site and effect of the Siglec-9 inflammatory biomarker on human primary amine oxidase. Sci Rep 2018; 8:2086. [PMID: 29391504 PMCID: PMC5794975 DOI: 10.1038/s41598-018-20618-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/22/2018] [Indexed: 12/21/2022] Open
Abstract
Human primary amine oxidase (hAOC3), also known as vascular adhesion protein 1, mediates leukocyte rolling and trafficking to sites of inflammation by a multistep adhesion cascade. hAOC3 is absent on the endothelium of normal tissues and is kept upregulated during inflammatory conditions, which is an applicable advantage for imaging inflammatory diseases. Sialic acid binding immunoglobulin like-lectin 9 (Siglec-9) is a leukocyte ligand for hAOC3. The peptide (CARLSLSWRGLTLCPSK) based on the region of Siglec-9 that interacts with hAOC3, can be used as a specific tracer for hAOC3-targeted imaging of inflammation using Positron Emission Tomography (PET). In the present study, we show that the Siglec-9 peptide binds to hAOC3 and triggers its amine oxidase activity towards benzylamine. Furthermore, the hAOC3 inhibitors semicarbazide and imidazole reduce the binding of wild type and Arg/Ala mutated Siglec-9 peptides to hAOC3. Molecular docking of the Siglec-9 peptide is in accordance with the experimental results and predicts that the R3 residue in the peptide interacts in the catalytic site of hAOC3 when the topaquinone cofactor is in the non-catalytic on-copper conformation. The predicted binding mode of Siglec-9 peptide to hAOC3 is supported by the PET studies using rodent, rabbit and pig AOC3 proteins.
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Sahlgren C, Meinander A, Zhang H, Cheng F, Preis M, Xu C, Salminen TA, Toivola D, Abankwa D, Rosling A, Karaman DŞ, Salo-Ahen OMH, Österbacka R, Eriksson JE, Willför S, Petre I, Peltonen J, Leino R, Johnson M, Rosenholm J, Sandler N. Tailored Approaches in Drug Development and Diagnostics: From Molecular Design to Biological Model Systems. Adv Healthc Mater 2017; 6. [PMID: 28892296 DOI: 10.1002/adhm.201700258] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 05/04/2017] [Indexed: 12/13/2022]
Abstract
Approaches to increase the efficiency in developing drugs and diagnostics tools, including new drug delivery and diagnostic technologies, are needed for improved diagnosis and treatment of major diseases and health problems such as cancer, inflammatory diseases, chronic wounds, and antibiotic resistance. Development within several areas of research ranging from computational sciences, material sciences, bioengineering to biomedical sciences and bioimaging is needed to realize innovative drug development and diagnostic (DDD) approaches. Here, an overview of recent progresses within key areas that can provide customizable solutions to improve processes and the approaches taken within DDD is provided. Due to the broadness of the area, unfortunately all relevant aspects such as pharmacokinetics of bioactive molecules and delivery systems cannot be covered. Tailored approaches within (i) bioinformatics and computer-aided drug design, (ii) nanotechnology, (iii) novel materials and technologies for drug delivery and diagnostic systems, and (iv) disease models to predict safety and efficacy of medicines under development are focused on. Current developments and challenges ahead are discussed. The broad scope reflects the multidisciplinary nature of the field of DDD and aims to highlight the convergence of biological, pharmaceutical, and medical disciplines needed to meet the societal challenges of the 21st century.
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Affiliation(s)
- Cecilia Sahlgren
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
- Turku Centre for Biotechnology; Åbo Akademi University and University of Turku; FI-20520 Turku Finland
- Department of Biomedical Engineering; Technical University of Eindhoven; 5613 DR Eindhoven Netherlands
| | - Annika Meinander
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
| | - Hongbo Zhang
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Fang Cheng
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
| | - Maren Preis
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Chunlin Xu
- Faculty of Science and Engineering; Natural Materials Technology; Åbo Akademi University; FI-20500 Turku Finland
| | - Tiina A. Salminen
- Faculty of Science and Engineering; Structural Bioinformatics Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Diana Toivola
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
- Turku Center for Disease Modeling; University of Turku; FI-20520 Turku Finland
| | - Daniel Abankwa
- Department of Biomedical Engineering; Technical University of Eindhoven; 5613 DR Eindhoven Netherlands
| | - Ari Rosling
- Faculty of Science and Engineering; Polymer Technologies; Åbo Akademi University; FI-20500 Turku Finland
| | - Didem Şen Karaman
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Outi M. H. Salo-Ahen
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
- Faculty of Science and Engineering; Structural Bioinformatics Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Ronald Österbacka
- Faculty of Science and Engineering; Physics; Åbo Akademi University; FI-20500 Turku Finland
| | - John E. Eriksson
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
- Turku Centre for Biotechnology; Åbo Akademi University and University of Turku; FI-20520 Turku Finland
| | - Stefan Willför
- Faculty of Science and Engineering; Natural Materials Technology; Åbo Akademi University; FI-20500 Turku Finland
| | - Ion Petre
- Faculty of Science and Engineering; Computer Science; Åbo Akademi University; FI-20500 Turku Finland
| | - Jouko Peltonen
- Faculty of Science and Engineering; Physical Chemistry; Åbo Akademi University; FI-20500 Turku Finland
| | - Reko Leino
- Faculty of Science and Engineering; Organic Chemistry; Johan Gadolin Process Chemistry Centre; Åbo Akademi University; FI-20500 Turku Finland
| | - Mark Johnson
- Faculty of Science and Engineering; Structural Bioinformatics Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Jessica Rosenholm
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Niklas Sandler
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
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7
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Sahlgren C, Meinander A, Zhang H, Cheng F, Preis M, Xu C, Salminen TA, Toivola D, Abankwa D, Rosling A, Karaman DŞ, Salo-Ahen OMH, Österbacka R, Eriksson JE, Willför S, Petre I, Peltonen J, Leino R, Johnson M, Rosenholm J, Sandler N. Tailored Approaches in Drug Development and Diagnostics: From Molecular Design to Biological Model Systems. Adv Healthc Mater 2017. [DOI: 10.1002/adhm.201700258 10.1002/adhm.201700258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Affiliation(s)
- Cecilia Sahlgren
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
- Turku Centre for Biotechnology; Åbo Akademi University and University of Turku; FI-20520 Turku Finland
- Department of Biomedical Engineering; Technical University of Eindhoven; 5613 DR Eindhoven Netherlands
| | - Annika Meinander
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
| | - Hongbo Zhang
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Fang Cheng
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
| | - Maren Preis
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Chunlin Xu
- Faculty of Science and Engineering; Natural Materials Technology; Åbo Akademi University; FI-20500 Turku Finland
| | - Tiina A. Salminen
- Faculty of Science and Engineering; Structural Bioinformatics Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Diana Toivola
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
- Turku Center for Disease Modeling; University of Turku; FI-20520 Turku Finland
| | - Daniel Abankwa
- Department of Biomedical Engineering; Technical University of Eindhoven; 5613 DR Eindhoven Netherlands
| | - Ari Rosling
- Faculty of Science and Engineering; Polymer Technologies; Åbo Akademi University; FI-20500 Turku Finland
| | - Didem Şen Karaman
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Outi M. H. Salo-Ahen
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
- Faculty of Science and Engineering; Structural Bioinformatics Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Ronald Österbacka
- Faculty of Science and Engineering; Physics; Åbo Akademi University; FI-20500 Turku Finland
| | - John E. Eriksson
- Faculty of Science and Engineering; Cell Biology; Åbo Akademi University; FI-20520 Turku Finland
- Turku Centre for Biotechnology; Åbo Akademi University and University of Turku; FI-20520 Turku Finland
| | - Stefan Willför
- Faculty of Science and Engineering; Natural Materials Technology; Åbo Akademi University; FI-20500 Turku Finland
| | - Ion Petre
- Faculty of Science and Engineering; Computer Science; Åbo Akademi University; FI-20500 Turku Finland
| | - Jouko Peltonen
- Faculty of Science and Engineering; Physical Chemistry; Åbo Akademi University; FI-20500 Turku Finland
| | - Reko Leino
- Faculty of Science and Engineering; Organic Chemistry; Johan Gadolin Process Chemistry Centre; Åbo Akademi University; FI-20500 Turku Finland
| | - Mark Johnson
- Faculty of Science and Engineering; Structural Bioinformatics Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Jessica Rosenholm
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
| | - Niklas Sandler
- Faculty of Science and Engineering; Pharmaceutical Sciences Laboratory; Åbo Akademi University; FI-20520 Turku Finland
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Multivalent Interactions of Human Primary Amine Oxidase with the V and C22 Domains of Sialic Acid-Binding Immunoglobulin-Like Lectin-9 Regulate Its Binding and Amine Oxidase Activity. PLoS One 2016; 11:e0166935. [PMID: 27893774 PMCID: PMC5125647 DOI: 10.1371/journal.pone.0166935] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 11/07/2016] [Indexed: 11/20/2022] Open
Abstract
Sialic acid-binding immunoglobulin-like lectin-9 (Siglec-9) on leukocyte surface is a counter-receptor for endothelial cell surface adhesin, human primary amine oxidase (hAOC3), a target protein for anti-inflammatory agents. This interaction can be used to detect inflammation and cancer in vivo, since the labeled peptides derived from the second C2 domain (C22) of Siglec-9 specifically bind to the inflammation-inducible hAOC3. As limited knowledge on the interaction between Siglec-9 and hAOC3 has hampered both hAOC3-targeted drug design and in vivo imaging applications, we have now produced and purified the extracellular region of Siglec-9 (Siglec-9-EC) consisting of the V, C21 and C22 domains, modeled its 3D structure and characterized the hAOC3–Siglec-9 interactions using biophysical methods and activity/inhibition assays. Our results assign individual, previously unknown roles for the V and C22 domains. The V domain is responsible for the unusually tight Siglec-9–hAOC3 interactions whereas the intact C22 domain of Siglec-9 is required for modulating the enzymatic activity of hAOC3, crucial for the hAOC3-mediated leukocyte trafficking. By characterizing the Siglec-9-EC mutants, we could conclude that R120 in the V domain likely interacts with the terminal sialic acids of hAOC3 attached glycans whereas residues R284 and R290 in C22 are involved in the interactions with the active site channel of hAOC3. Furthermore, the C22 domain binding enhances the enzymatic activity of hAOC3 although the sialic acid-binding capacity of the V domain of Siglec-9 is abolished by the R120S mutation. To conclude, our results prove that the V and C22 domains of Siglec-9-EC interact with hAOC3 in a multifaceted and unique way, forming both glycan-mediated and direct protein-protein interactions, respectively. The reported results on the mechanism of the Siglec-9–hAOC3 interaction are valuable for the development of hAOC3-targeted therapeutics and diagnostic tools.
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HPLC-UV method for evaluation of inhibitors of plasma amine oxidase using derivatization of an aliphatic aldehyde product with TRIS. Anal Bioanal Chem 2016; 408:4799-807. [DOI: 10.1007/s00216-016-9572-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/13/2016] [Accepted: 04/15/2016] [Indexed: 12/29/2022]
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Finney J, Moon HJ, Ronnebaum T, Lantz M, Mure M. Human copper-dependent amine oxidases. Arch Biochem Biophys 2014; 546:19-32. [PMID: 24407025 DOI: 10.1016/j.abb.2013.12.022] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 12/24/2013] [Accepted: 12/26/2013] [Indexed: 12/11/2022]
Abstract
Copper amine oxidases (CAOs) are a class of enzymes that contain Cu(2+) and a tyrosine-derived quinone cofactor, catalyze the conversion of a primary amine functional group to an aldehyde, and generate hydrogen peroxide and ammonia as byproducts. These enzymes can be classified into two non-homologous families: 2,4,5-trihydroxyphenylalanine quinone (TPQ)-dependent CAOs and the lysine tyrosylquinone (LTQ)-dependent lysyl oxidase (LOX) family of proteins. In this review, we will focus on recent developments in the field of research concerning human CAOs and the LOX family of proteins. The aberrant expression of these enzymes is linked to inflammation, fibrosis, tumor metastasis/invasion and other diseases. Consequently, there is a critical need to understand the functions of these proteins at the molecular level, so that strategies targeting these enzymes can be developed to combat human diseases.
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Affiliation(s)
- Joel Finney
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA
| | - Hee-Jung Moon
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA
| | - Trey Ronnebaum
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA
| | - Mason Lantz
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA
| | - Minae Mure
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045, USA.
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Bligt-Lindén E, Pihlavisto M, Szatmári I, Otwinowski Z, Smith DJ, Lázár L, Fülöp F, Salminen TA. Novel pyridazinone inhibitors for vascular adhesion protein-1 (VAP-1): old target-new inhibition mode. J Med Chem 2013; 56:9837-48. [PMID: 24304424 DOI: 10.1021/jm401372d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vascular adhesion protein-1 (VAP-1) is a primary amine oxidase and a drug target for inflammatory and vascular diseases. Despite extensive attempts to develop potent, specific, and reversible inhibitors of its enzyme activity, the task has proven challenging. Here we report the synthesis, inhibitory activity, and molecular binding mode of novel pyridazinone inhibitors, which show specificity for VAP-1 over monoamine and diamine oxidases. The crystal structures of three inhibitor-VAP-1 complexes show that these compounds bind reversibly into a unique binding site in the active site channel. Although they are good inhibitors of human VAP-1, they do not inhibit rodent VAP-1 well. To investigate this further, we used homology modeling and structural comparison to identify amino acid differences, which explain the species-specific binding properties. Our results prove the potency and specificity of these new inhibitors, and the detailed characterization of their binding mode is of importance for further development of VAP-1 inhibitors.
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Affiliation(s)
- Eva Bligt-Lindén
- Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University , FI-20520 Turku, Finland
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12
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Mechanisms and mediators of inflammation: potential models for skin rejection and targeted therapy in vascularized composite allotransplantation. Clin Dev Immunol 2012; 2012:757310. [PMID: 23049603 PMCID: PMC3459345 DOI: 10.1155/2012/757310] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 08/09/2012] [Indexed: 02/07/2023]
Abstract
Vascularized composite allotransplantation (VCA) is an effective treatment option for patients suffering from limb loss or severe disfigurement. However, postoperative courses of VCA recipients have been complicated by skin rejection, and long-term immunosuppression remains a necessity for allograft survival. To widen the scope of this quality-of-life improving procedure minimization of immunosuppression in order to limit risks and side effects is needed. In some aspects, the molecular mechanisms and dynamics of skin allograft rejection seem similar to inflammatory skin conditions. T cells are key players in skin rejection and are recruited to the skin via activation of adhesion molecules, cytokines, and chemokines. Blocking these molecules has not only shown success in the treatment of inflammatory dermatoses, but also prolonged graft survival in various models of solid organ transplantation. In addition to T cell recruitment, ectopic lymphoid structures within the allograft associated with chronic rejection in solid organ transplantation might contribute to the strong alloimmune response towards the skin. Selectively targeting the molecules involved offers exciting novel therapeutic options in the prevention and treatment of skin rejection after VCA.
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13
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Shen SH, Wertz DL, Klinman JP. Implication for functions of the ectopic adipocyte copper amine oxidase (AOC3) from purified enzyme and cell-based kinetic studies. PLoS One 2012; 7:e29270. [PMID: 22238597 PMCID: PMC3251558 DOI: 10.1371/journal.pone.0029270] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/23/2011] [Indexed: 12/23/2022] Open
Abstract
AOC3 is highly expressed in adipocytes and smooth muscle cells, but its function in these cells is currently unknown. The in vivo substrate(s) of AOC3 is/are also unknown, but could provide an invaluable clue to the enzyme's function. Expression of untagged, soluble human AOC3 in insect cells provides a relatively simple means of obtaining pure enzyme. Characterization of enzyme indicates a 6% titer for the active site 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor and corrected k(cat) values as high as 7 s(-1). Substrate kinetic profiling shows that the enzyme accepts a variety of primary amines with different chemical features, including nonphysiological branched-chain and aliphatic amines, with measured k(cat)/K(m) values between 10(2) and 10(4) M(-1) s(-1). K(m)(O(2)) approximates the partial pressure of oxygen found in the interstitial space. Comparison of the properties of purified murine to human enzyme indicates k(cat)/K(m) values that are within 3 to 4-fold, with the exception of methylamine and aminoacetone that are ca. 10-fold more active with human AOC3. With drug development efforts investigating AOC3 as an anti-inflammatory target, these studies suggest that caution is called for when screening the efficacy of inhibitors designed against human enzymes in non-transgenic mouse models. Differentiated murine 3T3-L1 adipocytes show a uniform distribution of AOC3 on the cell surface and whole cell K(m) values that are reasonably close to values measured using purified enzymes. The latter studies support a relevance of the kinetic parameters measured with isolated AOC3 variants to adipocyte function. From our studies, a number of possible substrates with relatively high k(cat)/K(m) have been discovered, including dopamine and cysteamine, which may implicate a role for adipocyte AOC3 in insulin-signaling and fatty acid metabolism, respectively. Finally, the demonstrated AOC3 turnover of primary amines that are non-native to human tissue suggests possible roles for the adipocyte enzyme in subcutaneous bacterial infiltration and obesity.
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Affiliation(s)
- Sam H. Shen
- Department of Chemistry, University of California, Berkeley, California, United States of America
| | - Diana L. Wertz
- Department of Chemistry, University of California, Berkeley, California, United States of America
| | - Judith P. Klinman
- Department of Chemistry, University of California, Berkeley, California, United States of America
- Department of Molecular and Cell Biology and the California Institute for Quantitative Biosciences, University of California, Berkeley, California, United States of America
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Characterization of the in vitro binding and inhibition kinetics of primary amine oxidase/vascular adhesion protein-1 by glucosamine. Biochim Biophys Acta Gen Subj 2011; 1820:482-7. [PMID: 22202180 DOI: 10.1016/j.bbagen.2011.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 11/15/2011] [Accepted: 12/09/2011] [Indexed: 02/07/2023]
Abstract
BACKGROUND Primary-amine oxidase (PrAO) catalyzes the oxidative deamination of endogenous and exogenous primary amines and also functions, in some tissues, as an inflammation-inducible endothelial factor, known as vascular adhesion protein-1. VAP-1 mediates the slow rolling and adhesion of lymphocytes to endothelial cells in a number of inflammatory conditions, including inflammation of the synovium. METHODS Glucosamine binding to the enzyme was assessed spectrofluorometrically and the kinetics of inhibition of PrAO were determined spectrophotometrically through the use of direct or coupled assays, in the presence of different substrates. RESULTS Glucosamine is not a substrate for PrAO, but acts as a time-dependent inhibitor of PrAO activity, displaying mixed inhibition kinetics. The observed inhibition and binding were augmented in the presence of H(2)O(2). CONCLUSIONS Significant in vitro effects on PrAO require glucosamine in the millimolar concentration range and it is not clear at this stage whether a low but persistent level of PrAO inhibition might contribute to the anti-arthritic response. GENERAL SIGNIFICANCE This work was aimed at characterizing the interactions of PrAO/VAP-1 with glucosamine, a widely used "over-the-counter" supplement for the treatment of osteoarthritis.
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15
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Weston CJ, Adams DH. Hepatic consequences of vascular adhesion protein-1 expression. J Neural Transm (Vienna) 2011; 118:1055-64. [DOI: 10.1007/s00702-011-0647-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 04/10/2011] [Indexed: 01/09/2023]
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16
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Ernberg K, McGrath AP, Peat TS, Adams TE, Xiao X, Pham T, Newman J, McDonald IA, Collyer CA, Guss JM. A new crystal form of human vascular adhesion protein 1. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:1572-8. [PMID: 21139198 PMCID: PMC2998357 DOI: 10.1107/s1744309110041515] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/14/2010] [Indexed: 11/10/2022]
Abstract
Human vascular adhesion protein 1 (VAP-1) is involved in lymphocyte-endothelial cell adhesion and has been implicated in many human inflammatory diseases. VAP-1 is a member of the copper amine oxidase family of enzymes with a trihydroxyphenylalanine quinone (TPQ) cofactor. Previously characterized crystals of VAP-1 suffered from anisotropy and contained disordered regions; in addition, one form was consistently twinned. In an effort to grow crystals that diffracted to higher resolution for inhibitor-binding studies, a construct with an N-terminal deletion was made and expressed in the Chinese hamster ovary (CHO) glycosylation mutant cell line Lec8. Screening produced crystals that displayed some anisotropy and contained seven molecules per asymmetric unit. These crystals belonged to space group C2, with unit-cell parameters a=394.5, b=115.8, c=179.3 Å, β=112.3°. The structure was refined to a resolution of 2.9 Å, with Rcryst and Rfree values of 0.250 and 0.286, respectively.
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Affiliation(s)
- Karin Ernberg
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Aaron P. McGrath
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Thomas S. Peat
- Molecular and Health Technologies, CSIRO, Parkville, Victoria, Australia
| | - Timothy E. Adams
- Molecular and Health Technologies, CSIRO, Parkville, Victoria, Australia
| | - Xiaowen Xiao
- Molecular and Health Technologies, CSIRO, Parkville, Victoria, Australia
| | - Tam Pham
- Molecular and Health Technologies, CSIRO, Parkville, Victoria, Australia
| | - Janet Newman
- Molecular and Health Technologies, CSIRO, Parkville, Victoria, Australia
| | - Ian A. McDonald
- Pharmaxis Ltd, 20 Rodborough Road, Frenchs Forest, NSW 2086, Australia
| | - Charles A. Collyer
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - J. Mitchell Guss
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
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17
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McGrath AP, Hilmer KM, Collyer CA, Shepard EM, Elmore BO, Brown DE, Dooley DM, Guss JM. Structure and inhibition of human diamine oxidase. Biochemistry 2009; 48:9810-22. [PMID: 19764817 DOI: 10.1021/bi9014192] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Humans have three functioning genes that encode copper-containing amine oxidases. The product of the AOC1 gene is a so-called diamine oxidase (hDAO), named for its substrate preference for diamines, particularly histamine. hDAO has been cloned and expressed in insect cells and the structure of the native enzyme determined by X-ray crystallography to a resolution of 1.8 A. The homodimeric structure has the archetypal amine oxidase fold. Two active sites, one in each subunit, are characterized by the presence of a copper ion and a topaquinone residue formed by the post-translational modification of a tyrosine. Although hDAO shares 37.9% sequence identity with another human copper amine oxidase, semicarbazide sensitive amine oxidase or vascular adhesion protein-1, its substrate binding pocket and entry channel are distinctly different in accord with the different substrate specificities. The structures of two inhibitor complexes of hDAO, berenil and pentamidine, have been refined to resolutions of 2.1 and 2.2 A, respectively. They bind noncovalently in the active-site channel. The inhibitor binding suggests that an aspartic acid residue, conserved in all diamine oxidases but absent from other amine oxidases, is responsible for the diamine specificity by interacting with the second amino group of preferred diamine substrates.
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Affiliation(s)
- Aaron P McGrath
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006, Australia
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18
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Kaitaniemi S, Elovaara H, Grön K, Kidron H, Liukkonen J, Salminen T, Salmi M, Jalkanen S, Elima K. The unique substrate specificity of human AOC2, a semicarbazide-sensitive amine oxidase. Cell Mol Life Sci 2009; 66:2743-57. [PMID: 19588076 PMCID: PMC11115939 DOI: 10.1007/s00018-009-0076-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 06/08/2009] [Accepted: 06/12/2009] [Indexed: 12/01/2022]
Abstract
Semicarbazide-sensitive amine oxidases (SSAOs) catalyze oxidative deamination of primary amines, but the true physiological function of these enzymes is still poorly understood. Here, we have studied the functional and structural characteristics of a human cell-surface SSAO, AOC2, which is homologous to the better characterized family member, AOC3. The preferred in vitro substrates of AOC2 were found to be 2-phenylethylamine, tryptamine and p-tyramine instead of methylamine and benzylamine, the favored substrates of AOC3. Molecular modeling suggested structural differences between AOC2 and AOC3, which provide AOC2 with the capability to use the larger monoamines as substrates. Even though AOC2 mRNA was expressed in many tissues, the only tissues with detectable AOC2-like enzyme activity were found in the eye. Characterization of AOC2 will help in evaluating the contribution of this enzyme to the pathological processes attributed to the SSAO activity and in designing specific inhibitors for the individual members of the SSAO family.
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Affiliation(s)
- Sam Kaitaniemi
- MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland
| | - Heli Elovaara
- MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland
| | - Kirsi Grön
- MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland
| | - Heidi Kidron
- Department of Biochemistry and Pharmacy, Åbo Akademi University, 20520 Turku, Finland
| | - Janne Liukkonen
- Department of Ophthalmology, Turku University Hospital, 20521 Turku, Finland
| | - Tiina Salminen
- Department of Biochemistry and Pharmacy, Åbo Akademi University, 20520 Turku, Finland
| | - Marko Salmi
- MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland
| | - Sirpa Jalkanen
- MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland
| | - Kati Elima
- MediCity Research Laboratory, University of Turku, and National Institute for Health and Welfare, Tykistökatu 6, 20520 Turku, Finland
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19
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Jalkanen S, Salmi M. VAP-1 and CD73, Endothelial Cell Surface Enzymes in Leukocyte Extravasation. Arterioscler Thromb Vasc Biol 2008; 28:18-26. [DOI: 10.1161/atvbaha.107.153130] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Leukocyte extravasation from the blood into tissues is crucial for normal immune surveillance and in inflammation. Traditionally molecules belonging to selectin, chemokine, integrin, and immunoglobulin super families are thought to mediate the multiple adhesive and activation events needed for a successful emigration cascade. Recently, emerging evidence suggests that enzymes expressed on the surface of endothelial cells and leukocytes also contribute to the leukocyte extravasation cascade. Here we briefly review the role of vascular adhesion protein-1 (VAP-1) and CD73, 2 cell surface enzymes, in leukocyte migration form the blood into the tissues. Importantly, specific enzyme inhibitors, gene-deficient mice, and recombinant enzymes have recently unambiguously shown that the catalytic activity of these enzymes regulates the leukocyte traffic. The concept of enzymatic regulation of leukocyte extravasation provides new insight into the multi-step adhesion cascade and opens new possibilities for inhibiting inappropriate inflammatory reaction through the use of small molecule enzyme inhibitors.
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Affiliation(s)
- Sirpa Jalkanen
- From the MediCity Research Laboratory, and the Department of Microbiology and Immunology, University of Turku, and the Department of Bacterial and Inflammatory Diseases, National Public Health Institute, Turku, Finland
| | - Marko Salmi
- From the MediCity Research Laboratory, and the Department of Microbiology and Immunology, University of Turku, and the Department of Bacterial and Inflammatory Diseases, National Public Health Institute, Turku, Finland
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20
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O'Rourke AM, Wang EY, Miller A, Podar EM, Scheyhing K, Huang L, Kessler C, Gao H, Ton-Nu HT, Macdonald MT, Jones DS, Linnik MD. Anti-inflammatory effects of LJP 1586 [Z-3-fluoro-2-(4-methoxybenzyl)allylamine hydrochloride], an amine-based inhibitor of semicarbazide-sensitive amine oxidase activity. J Pharmacol Exp Ther 2007; 324:867-75. [PMID: 17993604 DOI: 10.1124/jpet.107.131672] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Semicarbazide-sensitive amine oxidase (SSAO, amine oxidase, copper-containing 3, and vascular adhesion protein-1) is a copper-containing enzyme that catalyzes the oxidative deamination of primary amines to an aldehyde, ammonia, and hydrogen peroxide. SSAO is also involved in leukocyte migration to sites of inflammation, and the enzymatic activity of SSAO is essential to this role. Thus, inhibition of SSAO enzyme activity represents a target for the development of small molecule anti-inflammatory compounds. Here, we have characterized the novel SSAO inhibitor, Z-3-fluoro-2-(4-methoxybenzyl)allylamine hydrochloride (LJP 1586), and assessed its anti-inflammatory activity. LJP 1586 is a potent inhibitor of rodent and human SSAO activity, with IC(50) values between 4 and 43 nM. The selectivity of LJP 1586 was confirmed with a broad panel of receptors and enzymes that included the monoamine oxidases A and B. Oral administration of LJP 1586 resulted in complete inhibition of rat lung SSAO, with an ED(50) between 0.1 and 1 mg/kg, and a pharmacodynamic half-life of greater than 24 h. In a mouse model of inflammatory leukocyte trafficking oral dosing with LJP 1586 resulted in significant dose-dependent inhibition of neutrophil accumulation, with an effect comparable to that of anti-leukocyte function-associated antigen-1 antibody. In a rat model of LPS-induced lung inflammation, administration of 10 mg/kg LJP 1586 resulted in a 55% significant reduction in transmigrated cells recovered by bronchoalveolar lavage. The results demonstrate that a selective, orally active small molecule inhibitor of SSAO is an effective anti-inflammatory compound in vivo and provide further support for SSAO as a therapeutic anti-inflammatory target.
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Affiliation(s)
- Anne M O'Rourke
- La Jolla Pharmaceutical Company, 6455 Nancy Ridge Drive, San Diego, CA 92121, USA.
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Zollner TM, Asadullah K, Schön MP. Targeting leukocyte trafficking to inflamed skin - still an attractive therapeutic approach? Exp Dermatol 2007; 16:1-12. [PMID: 17181631 DOI: 10.1111/j.1600-0625.2006.00503.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Research into leukocyte trafficking and its therapeutic exploitation appears to be a multistep process, just like the trafficking cascade itself. The initial euphoria evoked by an early understanding of the trafficking steps was followed by considerable disappointment following the clinical failure of the first selectin antagonist Cylexin (CY-1503), a sialyl Lewis(X) mimetic. The research area recovered and identified additional attractive pharmacological targets such as chemokine receptors and integrins. However, after lack of efficacy in anti-chemokine trials and the fatalities associated with anti VLA-4 therapy (Tysabri), the question arose again whether targeting leukocyte trafficking is really promising or whether such a complex, multistep process with many redundant and/or functionally overlapping molecules is simply too challenging to deal with. In this article, we delineate some pros and cons of this approach followed by a brief update on where we stand in the field and where we might move in the future.
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22
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Airenne TT, Nymalm Y, Kidron H, Smith DJ, Pihlavisto M, Salmi M, Jalkanen S, Johnson MS, Salminen TA. Crystal structure of the human vascular adhesion protein-1: unique structural features with functional implications. Protein Sci 2005; 14:1964-74. [PMID: 16046623 PMCID: PMC2279308 DOI: 10.1110/ps.051438105] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The expression of human vascular adhesion protein-1 (hVAP-1) is induced at sites of inflammation where extravasation of lymphocytes from blood to the peripheral tissue occurs. We have solved the X-ray structure of hVAP-1, a human copper amine oxidase (CAO), which is distinguished from other CAOs in being membrane-bound. The dimer structure reveals some intriguing features that may have fundamental roles in the adhesive and enzymatic functions of hVAP-1, especially regarding the role of hVAP-1 in inflammation, lymphocyte attachment, and signaling. Firstly, Leu469 at the substrate channel may play a key role in controlling the substrate entry; depending on its conformation, it either blocks or gives access to the active site. Secondly, sugar units are clearly observed at two of the six predicted N-glycosylation sites. Moreover, mutagenesis analysis showed that all of the predicted sites were glycosylated in the protein used for crystallization. Thirdly, the existence of a solvent-exposed RGD motif at the entrance to each active site in hVAP-1 suggests that it may have a functional role.
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Affiliation(s)
- Tomi T Airenne
- Department of Biochemistry and Pharmacy, Abo Akademi University, FIN-20520 Turku, Finland
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