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Allen CL, Wolanska K, Malhi NK, Benest AV, Wood ME, Amoaku W, Torregrossa R, Whiteman M, Bates DO, Whatmore JL. Hydrogen Sulfide Is a Novel Protector of the Retinal Glycocalyx and Endothelial Permeability Barrier. Front Cell Dev Biol 2021; 9:724905. [PMID: 34557493 PMCID: PMC8452977 DOI: 10.3389/fcell.2021.724905] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 07/29/2021] [Indexed: 12/27/2022] Open
Abstract
Significantly reduced levels of the anti-inflammatory gaseous transmitter hydrogen sulfide (H2S) are observed in diabetic patients and correlate with microvascular dysfunction. H2S may protect the microvasculature by preventing loss of the endothelial glycocalyx. We tested the hypothesis that H2S could prevent or treat retinal microvascular endothelial dysfunction in diabetes. Bovine retinal endothelial cells (BRECs) were exposed to normal (NG, 5.5 mmol/L) or high glucose (HG, 25 mmol/L) ± the slow-release H2S donor NaGYY4137 in vitro. Glycocalyx coverage (stained with WGA-FITC) and calcein-labeled monocyte adherence were measured. In vivo, fundus fluorescein angiography (FFA) was performed in normal and streptozotocin-induced (STZ) diabetic rats. Animals received intraocular injection of NaGYY4137 (1 μM) or the mitochondrial-targeted H2S donor AP39 (100 nM) simultaneously with STZ (prevention) or on day 6 after STZ (treatment), and the ratio of interstitial to vascular fluorescence was used to estimate apparent permeability. NaGYY4137 prevented HG-induced loss of BREC glycocalyx, increased monocyte binding to BRECs (p ≤ 0.001), and increased overall glycocalyx coverage (p ≤ 0.001). In rats, the STZ-induced increase in apparent retinal vascular permeability (p ≤ 0.01) was significantly prevented by pre-treatment with NaGYY4137 and AP39 (p < 0.05) and stabilized by their post-STZ administration. NaGYY4137 also reduced the number of acellular capillaries (collagen IV + /IB4-) in the diabetic retina in both groups (p ≤ 0.05). We conclude that NaGYY4137 and AP39 protected the retinal glycocalyx and endothelial permeability barrier from diabetes-associated loss of integrity and reduced the progression of diabetic retinopathy (DR). Hydrogen sulfide donors that target the glycocalyx may therefore be a therapeutic candidate for DR.
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Affiliation(s)
- Claire L Allen
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Katarzyna Wolanska
- The Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Naseeb K Malhi
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Andrew V Benest
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Mark E Wood
- Biosciences, College of Life and Environmental Science, University of Exeter, Exeter, United Kingdom
| | - Winfried Amoaku
- Academic Ophthalmology, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Roberta Torregrossa
- The Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Matthew Whiteman
- The Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - David O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Jacqueline L Whatmore
- The Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
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Bell JS, Adio AO, Pitt A, Hayman L, Thorn CE, Shore AC, Whatmore JL, Winlove CP. Microstructural Characterization of Resistance Artery Remodelling in Diabetes Mellitus. J Vasc Res 2021; 59:50-60. [PMID: 34544081 DOI: 10.1159/000517856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 05/04/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Microvascular remodelling is a symptom of cardiovascular disease. Despite the mechanical environment being recognized as a major contributor to the remodelling process, it is currently only understood in a rudimentary way. OBJECTIVE A morphological and mechanical evaluation of the resistance vasculature in health and diabetes mellitus. METHODS The cells and extracellular matrix of human subcutaneous resistance arteries from abdominal fat biopsies were imaged using two-photon fluorescence and second harmonic generation at varying transmural pressure. The results informed a two-layer mechanical model. RESULTS Diabetic resistance arteries reduced in wall area as pressure was increased. This was attributed to the presence of thick, straight collagen fibre bundles that braced the outer wall. The abnormal mechanical environment caused the internal elastic lamina and endothelial and vascular smooth muscle cell arrangements to twist. CONCLUSIONS Our results suggest diabetic microvascular remodelling is likely to be stress-driven, comprising at least 2 stages: (1) Laying down of adventitial bracing fibres that limit outward distension, and (2) Deposition of additional collagen in the media, likely due to the significantly altered mechanical environment. This work represents a step towards elucidating the local stress environment of cells, which is crucial to build accurate models of mechanotransduction in disease.
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Affiliation(s)
- James S Bell
- Department of Physics, University of Exeter, Exeter, United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom.,School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Aminat O Adio
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Andrew Pitt
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Lindsay Hayman
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Clare E Thorn
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Angela C Shore
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
| | - C Peter Winlove
- Department of Physics, University of Exeter, Exeter, United Kingdom
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Pranjol MZI, Gutowski NJ, Hannemann M, Whatmore JL. Cathepsin L Induces Proangiogenic Changes in Human Omental Microvascular Endothelial Cells via Activation of the ERK1/2 Pathway. Curr Cancer Drug Targets 2020; 19:231-242. [PMID: 30173647 DOI: 10.2174/1568009618666180831123951] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 08/09/2018] [Accepted: 08/16/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Metastasis still remains the major cause of therapeutic failure, poor prognosis and high mortality in epithelial ovarian cancer (EOC) patients. Previously, we showed that EOC cells secrete a range of factors with potential pro-angiogenic activity, in disease-relevant human omental microvascular endothelial cells (HOMECs), including the lysosomal protease cathepsin L (CathL). Thus, the aim of this study was to examine potential pro-proliferative and pro-migratory effects of CathL in HOMECs and the activated signalling pathways, and whether these proangiogenic responses are dependent on CathL-catalytic activity. METHODS HOMECs proliferation was investigated using WST-1, BrdU and CyQUANT assays. Cell migration was examined using a Cultrex Cell 96 transwell migration assay. Enzyme activity was assayed at various pHs using the CathL-specific fluorogenic substrate FY-CHO. Activation of cell signalling pathways was tested using a commercially available phosphokinase array and intact cellbased ELISAs. RESULTS We showed for the first time that CathL has a potent pro-proliferative and pro-migratory effect on HOMECs. For instance, CathL significantly increases HOMEC proliferation (134.8±14.7% vs control 100%) and migration (146.6±17.3% vs control 100%). Our data strongly suggest that these proangiogenic effects of CathL are mediated via a non-proteolytic mechanism. Finally, we show that CathL-induced activation of the ERK1/2 pathway is involved in inducing these cellular effects in HOMECs. CONCLUSION These data suggest that CathL acts as an extracellular ligand and plays an important pro-angiogenic, and thus pro-metastatic, role during EOC metastasis to the omentum, by activating the omental microvasculature, and thus can potentially be targeted therapeutically in the future.
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Affiliation(s)
- Md Zahidul I Pranjol
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon EX1 2LU, United Kingdom.,William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, United Kingdom
| | - Nicholas J Gutowski
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon EX1 2LU, United Kingdom.,Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon EX2 7JU, United Kingdom
| | - Michael Hannemann
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon EX2 7JU, United Kingdom
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon EX1 2LU, United Kingdom
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Tabish TA, Pranjol MZI, Whatmore JL, Zhang S. Status and Future Directions of Anti-metastatic Cancer Nanomedicines for the Inhibition of Cathepsin L. Front Nanotechnol 2020. [DOI: 10.3389/fnano.2020.00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Allen CL, Malhi NK, Whatmore JL, Bates DO, Arkill KP. Non-invasive measurement of retinal permeability in a diabetic rat model. Microcirculation 2020; 27:e12623. [PMID: 32352608 DOI: 10.1111/micc.12623] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 04/15/2020] [Accepted: 04/26/2020] [Indexed: 12/12/2022]
Abstract
OBJECTIVE The gold standard for measuring blood-retinal barrier permeability is the Evans blue assay. However, this technique has limitations in vivo, including non-specific tissue binding and toxicity. This study describes a non-toxic, high-throughput, and cost-effective alternative technique that minimizes animal usage. METHODS Sodium fluorescein fundus angiography was performed in non-diabetic and diabetic Brown Norway rats on days 0, 7, 14, 21, and 28. Sodium fluorescein intensity in the retinal interstitium and a main retinal vessel were measured over time. The intensity gradients were used to quantify retinal vascular permeability. Post-study eyes were fixed, dissected, and stained (isolectin B4) to measure required parameters for permeability quantification including total vessel length per retinal volume, radius, and thickness. RESULTS In the non-diabetic cohort retinal permeability remained constant over the 28-day study period. However, in the diabetic cohort there was a significant and progressive increase in retinal permeability from days 14-28 (P < .01, P < .001, P < .0001). CONCLUSIONS This novel imaging methodology in combination with mathematical quantification allows retinal permeability to be non-invasively and accurately measured at multiple time points in the same animal. In addition, this technique is a non-toxic, rapid, sensitive, and cost-effective alternative to the Evans blue assay.
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Affiliation(s)
- Claire L Allen
- Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University of Nottingham, UK
| | - Naseeb K Malhi
- Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University of Nottingham, UK
| | | | - David O Bates
- Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University of Nottingham, UK
| | - Kenton P Arkill
- Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, University of Nottingham, UK
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Aung MM, Slade K, Freeman LAR, Kos K, Whatmore JL, Shore AC, Gooding KM. Locally delivered GLP-1 analogues liraglutide and exenatide enhance microvascular perfusion in individuals with and without type 2 diabetes. Diabetologia 2019; 62:1701-1711. [PMID: 31203378 PMCID: PMC6677680 DOI: 10.1007/s00125-019-4918-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/24/2019] [Indexed: 12/19/2022]
Abstract
AIMS/HYPOTHESIS Glucagon-like peptide-1 (GLP-1) analogues reduce the risk of macrovascular disease in diabetes; however, little is known about their microvascular effects. This research examined the microvascular actions of the GLP-1 analogues liraglutide and exenatide in individuals with and without type 2 diabetes (study 1). It also explored the involvement of the GLP-1 receptor (study 2) and the nitric oxide pathway in mediating the microvascular effects of the analogues. METHODS Trial design: Studies 1 and 2 had a randomised, controlled, double-blind study design. Study 1 participants, intervention and methods: three participant groups were recruited: individuals with well-controlled type 2 diabetes, and obese and lean individuals without diabetes (21 participants per group). Liraglutide (0.06 mg), exenatide (0.5 μg) and saline (154 mmol/l NaCl; 0.9%) control were microinjected into separate sites in the dermis (forearm) in a randomised order, blinded to operator and participant. Skin microvascular perfusion was assessed by laser Doppler perfusion imaging. Outcomes were stabilised response (mean skin perfusion between 7.5 and 10 min post microinjection) and total response (AUC, normalised for baseline perfusion). Perfusion response to GLP-1 analogues was compared with saline within each group as well as between groups. Study 2 participants, intervention and methods: in healthy individuals (N = 16), liraglutide (0.06 mg) and saline microinjected sites were pretreated with saline or the GLP-1 receptor blocker, exendin-(9,39), in a randomised order, blinded to participant and operator. Outcomes were as above (stabilised response and total perfusion response). Perfusion response to liraglutide was compared between the saline and the exendin-(9,39) pretreated sites. In vitro study: the effects of liraglutide and exenatide on nitrate levels and endothelial nitric oxide synthase phosphorylation (activation) were examined using human microvascular endothelial cells. RESULTS Study 1 results: both analogues increased skin perfusion (stabilised response and total response) in all groups (n = 21 per group, p < 0.001), with the microvascular responses similar across groups (p ≥ 0.389). Study 2 results: liraglutide response (stabilised response and total response) was not influenced by pretreatment with exendin-(9,39) (70 nmol/l) (N = 15, one dataset excluded) (p ≥ 0.609). Liraglutide and exenatide increased nitrate production and endothelial nitric oxide synthase (eNOS) phosphorylation (p ≤ 0.020). CONCLUSIONS/INTERPRETATION Liraglutide and exenatide increased skin microvascular perfusion in individuals with and without well-controlled diabetes, potentially mediated, at least in part, by NO. TRIAL REGISTRATION ClinicalTrials.gov NCT01677104. FUNDING This work was supported by Diabetes UK (grant numbers: 09/0003955 and 12/0004600 [RW and JM Collins Legacy, Funded Studentship]).
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Affiliation(s)
- Myo Myo Aung
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5AX, UK
| | - Kate Slade
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5AX, UK
| | | | - Katarina Kos
- Obesity Research Group, University of Exeter Medical School, Exeter, UK
| | | | - Angela C Shore
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5AX, UK
- National Institute of Health Research Exeter Clinical Research Facility, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Kim M Gooding
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5AX, UK.
- National Institute of Health Research Exeter Clinical Research Facility, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK.
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Pranjol MZI, Zinovkin DA, Maskell ART, Stephens LJ, Achinovich SL, Los' DM, Nadyrov EA, Hannemann M, Gutowski NJ, Whatmore JL. Cathepsin L-induced galectin-1 may act as a proangiogenic factor in the metastasis of high-grade serous carcinoma. J Transl Med 2019; 17:216. [PMID: 31269957 PMCID: PMC6610868 DOI: 10.1186/s12967-019-1963-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/25/2019] [Indexed: 12/13/2022] Open
Abstract
Background New treatment options for metastasised high-grade serous carcinoma (HGSC) are urgently needed. HGSC frequently metastasises to the omentum, inducing angiogenesis in the local omental microvasculature to facilitate tumour growth. We previously showed that HGSC-secreted cathepsin L (CathL) induces pro-angiogenic changes in disease relevant human omental microvascular endothelial cells (HOMECs), suggesting a role in tumour angiogenesis. Here we investigate whether CathL acts by inducing local production of the carbohydrate-binding protein galectin-1 (Gal1), which has been reported to be involved in tumourigenesis in other tumours. Methods HOMECs were used for all experiments. Gal1 mRNA and protein levels were measured by RT-PCR and ELISA respectively. Gal1-induced cell proliferation was assessed using WST-1 assay, migration using a transwell assay and in vivo Gal1 expression by immunohistochemistry. Results CathL transcriptionally regulated HOMEC production and secretion of Gal1 via activation of NFκB (significantly inhibited by sulfasalazine). Gal1 significantly enhanced HOMEC migration (p < 0.001) and proliferation (p < 0.001), suggesting an autocrine action. The latter was significantly reduced by the MEK/ERK1/2 inhibitors U0126 and PD98059 suggesting downstream activation of this pathway. Immunohistochemical analysis of omenta from HGSC patients with or without metastatic disease demonstrated a positive correlation between Gal1 expression and number of microvessels (r = 0.8702, p < 0.001), and area of vessels (r = 0.7283, p < 0.001), supporting a proangiogenic role for Gal1 in omental metastases. Conclusion HOMEC Gal1 transcription and release in response to CathL secreted from metastasising HGSC acts in an autocrine manner on the local microvasculature to induce pro-angiogenic changes, highlighting a potential new therapeutic target. Electronic supplementary material The online version of this article (10.1186/s12967-019-1963-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Md Zahidul I Pranjol
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, EX1 2LU, UK.,William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Dmitry A Zinovkin
- Department of Pathology, Gomel State Medical University, 246000, Gomel, Belarus
| | - Annelie R T Maskell
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, EX1 2LU, UK
| | - Laura J Stephens
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, EX1 2LU, UK
| | - Sergey L Achinovich
- Department of Anatomical Pathology, Gomel Regional Clinical Oncological Dispensary, 246012, Gomel, Belarus
| | - Dmitry M Los'
- Gomel Regional Clinical Oncological Dispensary, 246012, Gomel, Belarus
| | - Eldar A Nadyrov
- Department of Pathology, Gomel State Medical University, 246000, Gomel, Belarus
| | - Michael Hannemann
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, EX2 5DW, UK
| | - Nicholas J Gutowski
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, EX1 2LU, UK.,Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, EX2 5DW, UK
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, EX1 2LU, UK.
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Abstract
Background Protein–graphene interactions have the potential to play a pivotal role in the future directions of nanomedicine. These interactions lead to diverse processes such as generation of protein coronas, nano–bio interfaces, particle wrapping, and biocatalytic processes that could determine the ultimate fate of graphene nanocomposites in biologic systems. However, such interactions and their effects on the bioavailability of graphene have not yet been widely appreciated, despite the fact that this is the primary surface in contact with cells. Methods This paper reports on the integrative physiochemical interaction between trypsin and graphene quantum dots (GQDs) to determine their potential biologic identity in enzyme engineering. This interaction was measured by a wide range of analytical methods. Results Definitive binding and modulation of trypsin–GQDs was demonstrated for the first time by use of vibrational spectroscopy and wetting transparency, which revealed that trypsin was absorbed on GQDs’ surface through its cationic and hydrophilic residues. Our findings suggested that trypsin’s active sites were stabilized and protected by the GQDs, which were likely to be responsible for the high bioavailability of GQDs in enzymes. Conclusion Our work demonstrates the efficacy of GQDs as an enzyme modulator with high specificity, and their great application potential in enzyme engineering as well as enzyme-based therapies.
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Affiliation(s)
- Tanveer A Tabish
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK.,Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Md Zahidul I Pranjol
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Ilayda Karadag
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - David W Horsell
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Shaowei Zhang
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
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Tabish TA, Pranjol MZI, Hayat H, Rahat AAM, Abdullah TM, Whatmore JL, Zhang S. In vitro toxic effects of reduced graphene oxide nanosheets on lung cancer cells. Nanotechnology 2017; 28:504001. [PMID: 29064374 DOI: 10.1088/1361-6528/aa95a8] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The intriguing properties of reduced graphene oxide (rGO) have paved the way for a number of potential biomedical applications such as drug delivery, tissue engineering, gene delivery and bio-sensing. Over the last decade, there have been escalating concerns regarding the possible toxic effects, behaviour and fate of rGO in living systems and environments. This paper reports on integrative chemical-biological interactions of rGO with lung cancer cells, i.e. A549 and SKMES-1, to determine its potential toxicological impacts on them, as a function of its concentration. Cell viability, early and late apoptosis and necrosis were measured to determine oxidative stress potential, and induction of apoptosis for the first time by comparing two lung cancer cells. We also showed the general trend between cell death rates and concentrations for different cell types using a Gaussian process regression model. At low concentrations, rGO was shown to significantly produce late apoptosis and necrosis rather than early apoptotic events, suggesting that it was able to disintegrate the cellular membranes in a dose dependent manner. For the toxicity exposures undertaken, late apoptosis and necrosis occurred, which was most likely resultant from limited bioavailability of unmodified rGO in lung cancer cells.
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Affiliation(s)
- Tanveer A Tabish
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, United Kingdom
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Pranjol MZI, Gutowski NJ, Hannemann M, Whatmore JL. Cathepsin D non-proteolytically induces proliferation and migration in human omental microvascular endothelial cells via activation of the ERK1/2 and PI3K/AKT pathways. Biochim Biophys Acta Mol Cell Res 2017; 1865:25-33. [PMID: 29024694 DOI: 10.1016/j.bbamcr.2017.10.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/04/2017] [Accepted: 10/08/2017] [Indexed: 11/18/2022]
Abstract
Epithelial ovarian cancer (EOC) frequently metastasises to the omentum, a process that requires pro-angiogenic activation of human omental microvascular endothelial cells (HOMECs) by tumour-secreted factors. We have previously shown that ovarian cancer cells secrete a range of factors that induce pro-angiogenic responses e.g. migration, in HOMECs including the lysosomal protease cathepsin D (CathD). However, the cellular mechanism by which CathD induces these cellular responses is not understood. The aim of this study was to further examine the pro-angiogenic effects of CathD in HOMECs i.e. proliferation and migration, to investigate whether these effects are dependent on CathD catalytic activity and to delineate the intracellular signalling kinases activated by CathD. We report, for the first time, that CathD significantly increases HOMEC proliferation and migration via a non-proteolytic mechanism resulting in activation of ERK1/2 and AKT. These data suggest that EOC cancer secreted CathD acts as an extracellular ligand and may play an important pro-angiogenic, and thus pro-metastatic, role by activating the omental microvasculature during EOC metastasis to the omentum.
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Affiliation(s)
- Md Zahidul I Pranjol
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon EX1 2LU, UK
| | - Nicholas J Gutowski
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon EX1 2LU, UK; Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon EX2 7JU, UK
| | - Michael Hannemann
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon EX2 7JU, UK
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon EX1 2LU, UK.
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Bell JS, Adio AO, Pitt A, Hayman L, Thorn CE, Shore AC, Whatmore JL, Winlove CP. Microstructure and mechanics of human resistance arteries. Am J Physiol Heart Circ Physiol 2016; 311:H1560-H1568. [PMID: 27663767 PMCID: PMC5206342 DOI: 10.1152/ajpheart.00002.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 09/17/2016] [Indexed: 12/26/2022]
Abstract
Vascular diseases such as diabetes and hypertension cause changes to the vasculature that can lead to vessel stiffening and the loss of vasoactivity. The microstructural bases of these changes are not presently fully understood. We present a new methodology for stain-free visualization, at a microscopic scale, of the morphology of the main passive components of the walls of unfixed resistance arteries and their response to changes in transmural pressure. Human resistance arteries were dissected from subcutaneous fat biopsies, mounted on a perfusion myograph, and imaged at varying transmural pressures using a multimodal nonlinear microscope. High-resolution three-dimensional images of elastic fibers, collagen, and cell nuclei were constructed. The honeycomb structure of the elastic fibers comprising the internal elastic layer became visible at a transmural pressure of 30 mmHg. The adventitia, comprising wavy collagen fibers punctuated by straight elastic fibers, thinned under pressure as the collagen network straightened and pulled taut. Quantitative measurements of fiber orientation were made as a function of pressure. A multilayer analytical model was used to calculate the stiffness and stress in each layer. The adventitia was calculated to be up to 10 times as stiff as the media and experienced up to 8 times the stress, depending on lumen diameter. This work reveals that pressure-induced reorganization of fibrous proteins gives rise to very high local strain fields and highlights the unique mechanical roles of both fibrous networks. It thereby provides a basis for understanding the micromechanical significance of structural changes that occur with age and disease.
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Affiliation(s)
- J S Bell
- Department of Physics, University of Exeter, Exeter, United Kingdom; .,Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
| | - A O Adio
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom; and
| | - A Pitt
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom; and
| | - L Hayman
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom; and
| | - C E Thorn
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom; and
| | - A C Shore
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Exeter, United Kingdom; and
| | - J L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
| | - C P Winlove
- Department of Physics, University of Exeter, Exeter, United Kingdom
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Gerő D, Torregrossa R, Perry A, Waters A, Le-Trionnaire S, Whatmore JL, Wood M, Whiteman M. The novel mitochondria-targeted hydrogen sulfide (H 2S) donors AP123 and AP39 protect against hyperglycemic injury in microvascular endothelial cells in vitro. Pharmacol Res 2016; 113:186-198. [PMID: 27565382 PMCID: PMC5113977 DOI: 10.1016/j.phrs.2016.08.019] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/10/2016] [Accepted: 08/14/2016] [Indexed: 01/24/2023]
Abstract
The development of diabetic vascular complications is initiated, at least in part, by mitochondrial reactive oxygen species (ROS) production in endothelial cells. Hyperglycemia induces superoxide production in the mitochondria and initiates changes in the mitochondrial membrane potential that leads to mitochondrial dysfunction. Hydrogen sulfide (H2S) supplementation has been shown to reduce the mitochondrial oxidant production and shows efficacy against diabetic vascular damage in vivo. However, the half-life of H2S is very short and it is not specific for the mitochondria. We have therefore evaluated two novel mitochondria-targeted anethole dithiolethione and hydroxythiobenzamide H2S donors (AP39 and AP123 respectively) at preventing hyperglycemia-induced oxidative stress and metabolic changes in microvascular endothelial cells in vitro. Hyperglycemia (HG) induced significant increase in the activity of the citric acid cycle and led to elevated mitochondrial membrane potential. Mitochondrial oxidant production was increased and the mitochondrial electron transport decreased in hyperglycemic cells. AP39 and AP123 (30–300 nM) decreased HG-induced hyperpolarisation of the mitochondrial membrane and inhibited the mitochondrial oxidant production. Both H2S donors (30–300 nM) increased the electron transport at respiratory complex III and improved the cellular metabolism. Targeting H2S to mitochondria retained the cytoprotective effect of H2S against glucose-induced damage in endothelial cells suggesting that the molecular target of H2S action is within the mitochondria. Mitochondrial targeting of H2S also induced >1000-fold increase in the potency of H2S against hyperglycemia-induced injury. The high potency and long-lasting effect elicited by these H2S donors strongly suggests that these compounds could be useful against diabetic vascular complications.
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Affiliation(s)
- Domokos Gerő
- University of Exeter Medical School, Exeter, UK.
| | - Roberta Torregrossa
- University of Exeter Medical School, Exeter, UK; Biosciences, College of Life and Environmental Sciences, University of Exeter, UK
| | - Alexis Perry
- Biosciences, College of Life and Environmental Sciences, University of Exeter, UK
| | | | - Sophie Le-Trionnaire
- IRSET-UMR INSERM U1085, Equipe 3-Stress, Membrane et Signalisation, Rennes Cedex, France
| | | | - Mark Wood
- Biosciences, College of Life and Environmental Sciences, University of Exeter, UK
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Rai S, Nejadhamzeeigilani Z, Gutowski NJ, Whatmore JL. Loss of the endothelial glycocalyx is associated with increased E-selectin mediated adhesion of lung tumour cells to the brain microvascular endothelium. J Exp Clin Cancer Res 2015; 34:105. [PMID: 26407999 PMCID: PMC4582832 DOI: 10.1186/s13046-015-0223-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/14/2015] [Indexed: 12/21/2022]
Abstract
Background Arrest of metastasising lung cancer cells to the brain microvasculature maybe mediated by interactions between ligands on circulating tumour cells and endothelial E-selectin adhesion molecules; a process likely to be regulated by the endothelial glycocalyx. Using human cerebral microvascular endothelial cells and non-small cell lung cancer (NSCLC) cell lines, we describe how factors secreted by NSCLC cells i.e. cystatin C, cathepsin L, insulin-like growth factor-binding protein 7 (IGFBP7), vascular endothelial growth factor (VEGF) and tumour necrosis factor-alpha (TNF-α), damage the glycocalyx and enhance initial contacts between lung tumour and cerebral endothelial cells. Methods Endothelial cells were treated with tumour secreted-proteins or lung tumour conditioned medium (CM). Surface levels of E-selectin were quantified by ELISA. Adhesion of A549 and SK-MES-1 cells was examined under flow conditions (1 dyne/cm2). Alterations in the endothelial glycocalyx were quantified by binding of fluorescein isothiocyanate-linked wheat germ agglutinin (WGA-FITC). Results A549 and SK-MES-1 CM and secreted-proteins significantly enhanced endothelial surface E-selectin levels after 30 min and 4 h and tumour cell adhesion after 30 min, 4 and 24 h. Both coincided with significant glycocalyx degradation; A549 and SK-MES-1 CM removing 55 ± 12 % and 58 ± 18.7 % of WGA-FITC binding, respectively. Inhibition of E-selectin binding by monoclonal anti-E-selectin antibody completely attenuated tumour cell adhesion. Conclusion These data suggest that metastasising lung cancer cells facilitate their own adhesion to the brain endothelium by secreting factors that damage the endothelial glycocalyx, resulting in exposure of the previously shielded adhesion molecules and engagement of the E-selectin-mediated adhesion axis. Electronic supplementary material The online version of this article (doi:10.1186/s13046-015-0223-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Srijana Rai
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's campus, Exeter, EX1 2LU, UK.
| | - Zaynab Nejadhamzeeigilani
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's campus, Exeter, EX1 2LU, UK.
| | - Nicholas J Gutowski
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's campus, Exeter, EX1 2LU, UK. .,Royal Devon and Exeter NHS Foundation Trust, Barrack road, Exeter, EX2 5DW, UK.
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, St. Luke's campus, Exeter, EX1 2LU, UK.
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Lo Faro ML, Fox B, Whatmore JL, Winyard PG, Whiteman M. Hydrogen sulfide and nitric oxide interactions in inflammation. Nitric Oxide 2014; 41:38-47. [PMID: 24929214 DOI: 10.1016/j.niox.2014.05.014] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/13/2014] [Accepted: 05/29/2014] [Indexed: 12/30/2022]
Abstract
Together with carbon monoxide (CO), nitric oxide (NO) and hydrogen sulfide (H2S) form a group of physiologically important gaseous transmitters, sometimes referred to as the "gaseous triumvirate". The three molecules share a wide range of physical and physiological properties: they are small gaseous molecules, able to freely penetrate cellular membranes; they are all produced endogenously in the body and they seem to exert similar biological functions. In the cardiovascular system, for example, they are all vasodilators, promote angiogenesis and protect tissues against damage (e.g. ischemia-reperfusion injury). In addition, they have complex roles in inflammation, with both pro- and anti-inflammatory effects reported. Researchers have focused their efforts in understanding and describing the roles of each of these molecules in different physiological systems, and in the past years attention has also been given to the gases interaction or "cross-talk". This review will focus on the role of NO and H2S in inflammation and will give an overview of the evidence collected so far suggesting the importance of their cross-talk in inflammatory processes.
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Affiliation(s)
- Maria Letizia Lo Faro
- University of Exeter Medical School, Saint Luke's Campus, Heavitree Road, EX1 2LU Exeter, UK.
| | - Bridget Fox
- University of Exeter Medical School, Saint Luke's Campus, Heavitree Road, EX1 2LU Exeter, UK.
| | - Jacqueline L Whatmore
- University of Exeter Medical School, Saint Luke's Campus, Heavitree Road, EX1 2LU Exeter, UK.
| | - Paul G Winyard
- University of Exeter Medical School, Saint Luke's Campus, Heavitree Road, EX1 2LU Exeter, UK.
| | - Matthew Whiteman
- University of Exeter Medical School, Saint Luke's Campus, Heavitree Road, EX1 2LU Exeter, UK.
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Winiarski BK, Cope N, Alexander M, Pilling LC, Warren S, Acheson N, Gutowski NJ, Whatmore JL. Clinical Relevance of Increased Endothelial and Mesothelial Expression of Proangiogenic Proteases and VEGFA in the Omentum of Patients with Metastatic Ovarian High-Grade Serous Carcinoma. Transl Oncol 2014; 7:267-276.e4. [PMID: 24913675 PMCID: PMC4101350 DOI: 10.1016/j.tranon.2014.02.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 01/07/2023] Open
Abstract
Epithelial ovarian cancer (EOC) metastasis to the omentum requires implantation and angiogenesis. We propose that prometastatic changes in the omental endothelium (for angiogenesis) and mesothelium (for implantation) are critical. We investigated the expression of angiogenic proteases [cathepsin D (CD), cathepsin L (CL), and matrix metalloproteinase 2 (MMP2) and MMP9] and vascular endothelial growth factor A (VEGFA) in the mesothelium and endothelium of omentum from patients with EOC with omental metastases and control patients with benign ovarian tumors. Endothelial expression of CL, VEGFA, and MMP9 and mesothelial expression of VEGFA, MMP9, and CD were significantly increased in patients with metastasized EOC. High expression of MMP9 and VEGFA in endothelium and mesothelium and CD in mesothelium was positively associated with poor disease-specific survival (DSS). High MMP9 expression in either endothelium or mesothelium and presence of ascites prospectively showed the greatest risk of shorter DSS [hazard ratio (HR)= 6.16, 95% confidence interval (CI) = 1.76-21.6, P = .0045; HR = 11.42, 95% CI = 2.59-50.35, P = .0013; and HR = 6.35, 95% CI = 2.01-20.1, P = .002, respectively]. High endothelial MMP9 expression and ascites were independent predictors of reduced DSS and overall survival, together resulting in worst patient prognosis. Our data show that omental metastasis of EOC is associated with increased proangiogenic protein expression in the omental endothelium and mesothelium.
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Affiliation(s)
- Boleslaw K Winiarski
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Nichola Cope
- Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | | | - Luke C Pilling
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Sophie Warren
- Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Nigel Acheson
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK; Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Nicholas J Gutowski
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK; Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Jacqueline L Whatmore
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK.
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16
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Le Trionnaire S, Perry A, Szczesny B, Szabo C, Winyard PG, Whatmore JL, Wood ME, Whiteman M. The synthesis and functional evaluation of a mitochondria-targeted hydrogen sulfide donor, (10-oxo-10-(4-(3-thioxo-3H-1,2-dithiol-5-yl)phenoxy)decyl)triphenylphosphonium bromide (AP39). Med Chem Commun 2014. [DOI: 10.1039/c3md00323j] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondrial dysfunction is observed in many diseases. Targeting H2S generation to mitochondria may be cytoprotective.
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Affiliation(s)
| | - Alexis Perry
- Biosciences
- College of Environmental and Life Sciences
- University of Exeter
- Exeter EX4 4QD, UK
| | - Bartosz Szczesny
- Department of Anesthesiology
- University of Texas Medical Branch
- Galveston, USA
| | - Csaba Szabo
- Department of Anesthesiology
- University of Texas Medical Branch
- Galveston, USA
| | - Paul G. Winyard
- University of Exeter Medical School
- St. Luke's Campus
- Exeter EX1 2LU, UK
| | | | - Mark E. Wood
- Biosciences
- College of Environmental and Life Sciences
- University of Exeter
- Exeter EX4 4QD, UK
| | - Matthew Whiteman
- University of Exeter Medical School
- St. Luke's Campus
- Exeter EX1 2LU, UK
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17
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Turner PA, Samiullah, Whatmore JL, Shipman M. Stereocontrolled synthesis of a d-amicetose functionalised tetrahydroxanthone related to kigamicin A. Tetrahedron Lett 2013. [DOI: 10.1016/j.tetlet.2013.09.091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Kendall AC, Whatmore JL, Winyard PG, Smerdon GR, Eggleton P. Hyperbaric oxygen treatment reduces neutrophil-endothelial adhesion in chronic wound conditions through S-nitrosation. Wound Repair Regen 2013; 21:860-8. [DOI: 10.1111/wrr.12108] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 07/10/2013] [Indexed: 01/19/2023]
Affiliation(s)
| | | | - Paul G. Winyard
- Exeter University School of Medicine; Exeter Devon United Kingdom
| | - Gary R. Smerdon
- Diving Diseases Research Centre; Plymouth Devon United Kingdom
| | - Paul Eggleton
- Exeter University School of Medicine; Exeter Devon United Kingdom
- Department of Biochemistry; University of Alberta; Edmonton Alberta Canada
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Whiteman M, Perry A, Trionnaire SL, Whatmore JL, Ahmed T, Fox B, Kerr P, Haigh R, Winyard PG, Wood ME. PL04 Modulation of inflammatory and vascular signalling by novel slow release and mitochondria-targeted H2S donors. Nitric Oxide 2013. [DOI: 10.1016/j.niox.2013.06.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Kendall AC, Whatmore JL, Harries LW, Winyard PG, Eggleton P, Smerdon GR. Different oxygen treatment pressures alter inflammatory gene expression in human endothelial cells. Undersea Hyperb Med 2013; 40:115-123. [PMID: 23682543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Hyperbaric oxygen has proven to be a useful treatment for chronic wounds. However, therapeutic conditions vary between treatment centers, and we wished to investigate the effects of different treatment pressures on cells under inflammatory conditions. Endothelial cells were exposed to a chronic wound model comprising hypoxia (2% O2 at 1 atmosphere absolute (atm abs); PO2 approximately 2 kPa) in the presence of 0.5 microg/ml lipopolysaccharide and 1 ng/ml TNF-alpha for 24 hours, then treated with normobaric oxygen (NBO2; 95%O2/5%CO2 at 1.0 atm abs; PO2 approximately 96.3 kPa), hyperbaric oxygen (HBO2) at 1.5 atm abs (1.5HBO2; 96.7%O2/3.3%CO2 at 1.5 atm abs; PO2 approximately 147 kPa), and HBO2 at 2.4 atm abs (2.4HBO2; 97.9%O2/2.1%CO2 at 2.4 atm abs; PO2 approximately 238 kPa). The mRNA expression of 92 inflammatory genes was then analyzed, and we identified changes in genes involved in adhesion molecule expression, angiogenesis and tissue remodeling, intracellular signaling, and cellular oxygen responses and redox signaling. We noted differences in expression between different treatment pressures, highlighting the need for further research into the use of different therapeutic protocols in the treatment of inflammatory conditions such as chronic wounds.
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21
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Gutowski N, Rai S, Whatmore JL. LUNG TUMOUR SECRETED VEGF AND TNF-α INDUCE EXPRESSION OF ADHESION MOLECULES ON CEREBRAL ENDOTHELIAL CELLS. J Neurol Psychiatry 2012. [DOI: 10.1136/jnnp-2012-304200a.94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Winiarski BK, Acheson N, Gutowski NJ, McHarg S, Whatmore JL. An improved and reliable method for isolation of microvascular endothelial cells from human omentum. Microcirculation 2012; 18:635-45. [PMID: 21854489 DOI: 10.1111/j.1549-8719.2011.00128.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Despite an increasing research demand for human microvascular endothelial cells, isolation of primary endothelial cells from human tissue remains difficult. The omentum, a highly vascular visceral adipose tissue, could provide an excellent source of these cells. METHODS A reliable method to isolate HOMECs has been developed. It consists of initial enzymatic digestion (to deplete cell contaminants), followed by further digestion, selective filtration, and immunoselection using Dynabeads coated with CD31 antibody. Cultures were characterized for expression of endothelial cell markers and their ability to undergo VEGF-dependent in vitro tube structure formation. RESULTS Omental-derived cultures of microvascular endothelial cells were achieved with <5% contamination of other cell types. The endothelial origin of cells was confirmed by the constitutive expression of a range of vascular endothelial markers (CD31, CD105, vWF) and internalization of DiI-AcLDL. Furthermore, cultures were negative for lymphatic endothelial markers, underwent in vitro angiogenesis, and exhibited typical endothelial morphology. CONCLUSIONS This isolation method produces homogeneous HOMEC cultures that can be maintained in vitro for at least six passages without loss of cellular features characterizing endothelial cells.
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Affiliation(s)
- Boleslaw K Winiarski
- Institute of Biomedical and Clinical Science, Peninsula Medical School, University of Exeter, St Luke's Campus, Exeter, Devon, UK
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23
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Kendall AC, Whatmore JL, Harries LW, Winyard PG, Smerdon GR, Eggleton P. Changes in inflammatory gene expression induced by hyperbaric oxygen treatment in human endothelial cells under chronic wound conditions. Exp Cell Res 2011; 318:207-16. [PMID: 22063471 DOI: 10.1016/j.yexcr.2011.10.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 10/07/2011] [Accepted: 10/23/2011] [Indexed: 12/15/2022]
Abstract
Hyperbaric oxygen (HBO) therapy involves the inhalation of 100% oxygen, whilst inside a chamber at greater than atmospheric pressure. It is an effective treatment for chronic diabetic wounds, although the molecular mechanisms involved remain unclear. We hypothesised that HBO could alter inflammatory gene expression in human endothelial cells via a reactive oxygen/nitrogen species-mediated pathway. Endothelial cells were exposed to a chronic wound model comprising hypoxia (2% O(2) at 1 atmosphere absolute (ATA); PO(2) ~2 kPa) in the presence of lipopolysaccharide and TNF-α for 24h, then treated with HBO for 90 min (97.5% O(2) at 2.4 ATA; PO(2) ~237 kPa). 5h post-HBO, 19 genes involved in adhesion, angiogenesis, inflammation and oxidative stress were downregulated. Notably, only angiogenin gene expression, which promotes both angiogenesis and nitric oxide production (reflected by increased eNOS protein expression in this study), was upregulated. This led to a decrease in endothelial IL-8 mRNA and protein, which could help alleviate inflammatory processes during chronic wound healing. This was no longer evident 22.5h post-HBO, demonstrating the importance of daily exposures in HBO treatment protocols. These studies indicate that elevated oxygen transiently regulates inflammatory gene expression in endothelial cells, which may enhance chronic wound healing.
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Turner PA, Griffin EM, Whatmore JL, Shipman M. Tetrahydroxanthones by Sequential Pd-Catalyzed C−O and C−C Bond Construction and Use in the Identification of the “Antiausterity” Pharmacophore of the Kigamicins. Org Lett 2011; 13:1056-9. [DOI: 10.1021/ol103103n] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Penelope A. Turner
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom, and Peninsula Medical School, University of Exeter, St Luke’s Campus, Heavitree, Exeter, EX1 2LU, United Kingdom
| | - Ellanna M. Griffin
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom, and Peninsula Medical School, University of Exeter, St Luke’s Campus, Heavitree, Exeter, EX1 2LU, United Kingdom
| | - Jacqueline L. Whatmore
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom, and Peninsula Medical School, University of Exeter, St Luke’s Campus, Heavitree, Exeter, EX1 2LU, United Kingdom
| | - Michael Shipman
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom, and Peninsula Medical School, University of Exeter, St Luke’s Campus, Heavitree, Exeter, EX1 2LU, United Kingdom
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Whiteman M, Gooding KM, Whatmore JL, Ball CI, Mawson D, Skinner K, Tooke JE, Shore AC. Adiposity is a major determinant of plasma levels of the novel vasodilator hydrogen sulphide. Diabetologia 2010; 53:1722-6. [PMID: 20414636 DOI: 10.1007/s00125-010-1761-5] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Accepted: 03/12/2010] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS Hydrogen sulphide is a recently identified endogenous endothelium-dependent vasodilator. Animal models of diabetes have shown that low plasma H(2)S levels are associated with marked endothelial dysfunction and insulin resistance. However, human studies on H(2)S and vascular function in health and disease are lacking. METHODS Plasma was obtained from male patients with type 2 diabetes (n = 11), overweight (n = 16) and lean (n = 11) volunteers. H(2)S levels were determined by zinc trap spectrophotometry. Anthropometric measurements (BMI/waist:hip ratio), lipid profile, systemic blood pressure, biochemical indices of diabetes (fasting glucose, insulin sensitivity, Hb(1Ac)) and microvascular function (minimum vascular resistance) were determined. RESULTS Median plasma H(2)S levels (25th, 75th percentiles) in age-matched lean, overweight and type 2 diabetes individuals were 38.9 (29.7, 45.1) micromol/l, 22.0 (18.6, 26.7) micromol/l and 10.5 (4.8, 22.0) micromol/l, respectively. Median plasma H(2)S levels were significantly lower in patients with type 2 diabetes compared with lean (p = 0.001, Mann-Whitney) and overweight participants (p = 0.008). Median plasma H(2)S levels in overweight participants were significantly lower than in lean controls (p = 0.003). Waist circumference was an independent predictor of plasma H(2)S (R (2) = 0.423, standardised beta: -0.650, p < 0.001). This relationship was independent of diabetes, which only contributed a further 5% to the model (R (2) = 0.477). Waist circumference or other measures of adiposity (waist:hip ratio/BMI) remained independent predictors of plasma H(2)S after adjustment for systolic blood pressure, microvascular function, insulin sensitivity, glycaemic control and lipid profile. CONCLUSIONS/INTERPRETATION Plasma H(2)S levels are reduced in overweight participants and patients with type 2 diabetes. Increasing adiposity is a major determinant of plasma H(2)S levels.
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Affiliation(s)
- M Whiteman
- Institute of Biomedical and Clinical Science, Peninsula Medical School, University of Exeter, St Luke's Campus, Magdalen Road, Exeter, Devon EX1 2LU, UK.
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Holley JE, Newcombe J, Whatmore JL, Gutowski NJ. Increased blood vessel density and endothelial cell proliferation in multiple sclerosis cerebral white matter. Neurosci Lett 2009; 470:65-70. [PMID: 20036712 DOI: 10.1016/j.neulet.2009.12.059] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 12/21/2009] [Accepted: 12/21/2009] [Indexed: 11/18/2022]
Abstract
Multiple sclerosis (MS) is primarily considered an inflammatory demyelinating disease, however the role of vasculature in MS pathogenesis is now receiving much interest. MS lesions often develop along blood vessels and alterations in blood brain barrier structure and function, with associated changes in the basement membrane, are pathological features. Nevertheless, the possibility of angiogenesis occurring in MS has received little attention. In this study we used triple label enzyme immunohistochemistry to investigate blood vessel density and endothelial cell proliferation in MS samples (n=39) compared with control tissue to explore evidence of angiogenesis in MS. The results showed that in all MS samples examined blood vessel density increased compared with controls. The greatest increase was found in subacute lesions where numbers of positively stained vessels increased from 43.9+/-8.5% in controls to 84.2+/-13.3% (P=0.001). Furthermore, using an antibody against endoglin (CD105), a specific marker of proliferating endothelial cells, which are characteristic of angiogenesis, we have shown that vessels containing proliferating endothelial cells were more pronounced in all MS tissue examined (normal-appearing white matter, acute, subacute and chronic lesions, P>or=0.027) compared with control and this was greatest in the MS normal-appearing white matter (68.8+/-19.8% versus 10.58+/-6.4%, P=0.003). These findings suggest that angiogenesis may play a role in lesion progression, failure of repair and scar formation.
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Affiliation(s)
- Janet E Holley
- Peninsula Medical School, University of Exeter, St Luke's Campus, Magdalen Road, Exeter, EX1 2LU, United Kingdom.
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Blanche EA, Maskell L, Colucci MA, Whatmore JL, Moody CJ. Synthesis of potential prodrug systems for reductive activation. Prodrugs for anti-angiogenic isoflavones and VEGF receptor tyrosine kinase inhibitory oxindoles. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.04.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Maskell L, Blanche EA, Colucci MA, Whatmore JL, Moody CJ. Synthesis and evaluation of prodrugs for anti-angiogenic pyrrolylmethylidenyl oxindoles. Bioorg Med Chem Lett 2007; 17:1575-8. [PMID: 17254788 DOI: 10.1016/j.bmcl.2006.12.108] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 12/21/2006] [Accepted: 12/26/2006] [Indexed: 11/24/2022]
Abstract
Potential prodrugs of inhibitors of VEGF-induced angiogenesis have been investigated. The prodrug systems studied were the 4-nitrobenzyl, 2-nitrophenylacetyl and 3-methyl-3-(3,6-dimethylbenzo-1,4-quinon-2-yl)butanoyl groups, readily attached to acidic OH or NH groups in drug molecules, and released upon bioreductive activation. The anti-angiogenic compounds studied were the pyrrolylmethylidenyl oxindole SU5416 (semaxanib) and its novel 6-hydroxy derivative. The potentially pro-anti-angiogenic compounds were assayed for their ability to block VEGF-induced angiogenesis in HUVECS in comparison to the free agents.
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Affiliation(s)
- Lesley Maskell
- Peninsula Medical School, St. Luke's Campus, Exeter EX1 2LU, UK
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Konopatskaya O, Shore AC, Tooke JE, Whatmore JL. A role for heterotrimeric GTP-binding proteins and ERK1/2 in insulin-mediated, nitric-oxide-dependent, cyclic GMP production in human umbilical vein endothelial cells. Diabetologia 2005; 48:595-604. [PMID: 15739119 DOI: 10.1007/s00125-004-1653-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 10/08/2004] [Indexed: 01/01/2023]
Abstract
AIMS/HYPOTHESIS Insulin is known to stimulate endothelial nitric oxide synthesis, although much remains unknown about the intracellular mechanisms involved. This study aims to examine, in human endothelial cells, the specific contribution of heterotrimeric Gi proteins and extracellular signal-regulated protein kinases 1/2 (ERK1/2) in insulin signalling upstream of nitric-oxide-dependent cyclic GMP production. METHODS Human umbilical vein endothelial cells were treated with 1 nmol/l insulin in the presence or absence of inhibitors of tyrosine kinases (erbstatin), Gi proteins (pertussis toxin) or ERK1/2 (PD098059 or U0126), and nitric oxide production was examined by quantification of intracellular cyclic GMP. Activation/phosphorylation of ERK1/2 by insulin was examined by immunoblotting with specific antibodies, and direct association of the insulin receptor with Gi proteins was examined by immunoprecipitation. RESULTS Treatment of cells with a physiological concentration of insulin (1 nmol/l) for 5 min increased nitric-oxide-dependent cyclic GMP accumulation by 3.3-fold, and this was significantly inhibited by erbstatin. Insulin-stimulated cyclic GMP production was significantly reduced by pertussis toxin and by the inhibitors of ERK1/2, PD098059 and U0126. Immunoblotting indicated that insulin stimulated the phosphorylation of ERK1/2 after 5 min and 1 h, and that this was completely abolished by pertussis toxin, but insensitive to the nitric oxide synthase inhibitor L-NAME. No direct interaction of the insulin receptor beta with Gialpha2 could be demonstrated by immunoprecipitation. CONCLUSIONS/INTERPRETATION This study demonstrates, for the first time, that nitric oxide production induced by physiologically relevant concentrations of insulin, is mediated by the post-receptor activation of a pertussis-sensitive GTP-binding protein and subsequent downstream activation of the ERK1/2 cascade.
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Affiliation(s)
- O Konopatskaya
- Institute for Biomedical and Clinical Science, Peninsula Medical School, Exeter, EX1 2LU, UK.
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Abstract
Astrocytic scar formation occurs subsequent to brain and spinal cord injury and impedes repair. The exact mechanisms of scar formation have yet to be elucidated but it is known that astrocytes within the scar have a different antigenic phenotype from normal or reactive astrocytes. Astrocyte cell culture offers a suitable system to identify factors that induce the scar phenotype as well as factors that reverse this process and that may help identify therapeutic strategies to treat astrogliosis. However, when placed in standard culture conditions, astrocytes become activated/reactive and express molecules characteristic of scar tissue in vivo. In the present study, we made use of this phenomenon to identify culture conditions that change the activated phenotype of cultured astrocytes into one characteristic of normal quiescent astrocytes. In particular, we examined the effect of extracellular matrix (ECM) proteins found in the human brain, on the phenotype of human adult astrocytes. Significantly fewer astrocytes expressed scar properties when grown on tenascin-C (TN-C) than those cultured on other ECM proteins or poly-L-lysine-coated dishes. TN-C also significantly reduced the proliferation rate of the astrocytes in vitro. In addition, further manipulation of culture conditions induced partial astrocyte reactivation. Our findings suggest that astrocytes grown on TN-C revert to a quiescent, nonactivated state that is partially reversible. This raises the possibility that therapeutic strategies aimed at manipulating TN-C levels during CNS injury may help reduce astrocytic scarring.
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Affiliation(s)
- Janet E Holley
- Institute of Biomedical and Clinical Sciences, Peninsula Medical School (Exeter), Department of Neurology, Royal Devon and Exeter Hospital, Exeter, United Kingdom.
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Davies MW, Maskell L, Shipman M, Slawin AMZ, Vidot SME, Whatmore JL. Studies Toward the Synthesis of Luminacin D: Assembly of Simplified Analogues Devoid of the Epoxide Displaying Antiangiogenic Activity. Org Lett 2004; 6:3909-12. [PMID: 15496061 DOI: 10.1021/ol048462v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] A series of structurally simplified luminacin analogues devoid of the epoxide ring are assembled in a stereocontrolled manner from 2,4-dimethoxybenzaldehyde using a syn-selective aldol reaction as the key step. The success of the approach is critically dependent on the nature and extent of the alcohol protecting groups. The synthetic analogues inhibit VEGF-stimulated angiogenesis in an in vitro assay indicating that the epoxide is not essential for biological activity in this compound class.
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Affiliation(s)
- Mark W Davies
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
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Barker AL, Konopatskaya O, Neal CR, Macpherson JV, Whatmore JL, Winlove CP, Unwin PR, Shore AC. Observation and characterisation of the glycocalyx of viable human endothelial cells using confocal laser scanning microscopy. Phys Chem Chem Phys 2004. [DOI: 10.1039/b312189e] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
AIMS Nitric oxide (NO) is an important regulator of cardiovascular homeostasis. Lysophosphatidylcholine (lyso-PC), a major constituent of oxidized low density lipoproteins (oxLDL), has been reported to impair nitric oxide-dependent vasodilatation. This study investigated the possible mechanism of the lyso-PC effect on insulin-stimulated NO-dependent of cyclic guanosine 3',5'-monophosphate (cGMP) generation in human endothelial cells. METHODS The intracellular concentration of cGMP in cultured human umbilical vein endothelial cells (HUVECs) was used to estimate NO production. The levels of endothelial nitric oxide synthase (eNOS) protein expression were assessed by Western blotting analyses. RESULTS Both insulin, at physiological concentration, and lyso-PC stimulated rapid and prolonged intracellular of cGMP production, and together induced a marked synergistic response (for short-term stimulation: 1185 +/- 285.9% over control level (100%) compared with insulin and lyso-PC alone (384.8 +/- 67.4% and 357 +/- 205%, respectively; P < 0.001), for long-term stimulation: 3495 +/- 1377%, compared with insulin and lyso-PC alone (663 +/- 131% and 487 +/- 250%, P = 0.002)). Stimulated levels of cGMP accumulation were completely abrogated by NOS inhibitor, indicating NO involvement in the effects of insulin and lyso-PC. Stimulated NO synthesis was not associated with altered eNOS protein expression. Cell subfractionation studies demonstrate that insulin and lyso-PC each alone induced translocation of eNOS from the membrane to the cytosolic compartment and together caused a synergistic translocation. CONCLUSIONS The presented data suggest that insulin and lyso-PC synergistically upregulate endothelial NO production via eNOS translocation from the membrane fraction to the cytosol. This study raises the possibility that an interplay between various factors accompanying diabetes can lead to endothelial NO overproduction or desensitization of NO-dependent responses. Appropriate rather than necessarily high levels of nitric oxide is the determinant of vascular health.
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Affiliation(s)
- O Konopatskaya
- Institute for Biomedical and Clinical Science, Peninsula Medical School, Noy Scott House, Haldon View Terrace, Exeter EX2 5EQ, UK.
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Whatmore JL, Swann E, Barraja P, Newsome JJ, Bunderson M, Beall HD, Tooke JE, Moody CJ. Comparative study of isoflavone, quinoxaline and oxindole families of anti-angiogenic agents. Angiogenesis 2003; 5:45-51. [PMID: 12549859 DOI: 10.1023/a:1021528628524] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A study designed to compare the effects on VEGF-induced angiogenesis of a number of known anti-angiogenic agents together with some novel derivatives thereof was undertaken. Thus the isoflavone biochanin A 1[structure: see text], indomethacin 2[structure: see text], the 3-arylquinoxaline SU1433 and its derivatives 3-6[structure: see text], the benzoic acid derivative 7[structure: see text], the oxindoles SU5416 8[structure: see text] and SU6668 11[structure: see text], together with their simple N-benzyl derivatives 9, 10, and 12[structure: see text] were selected for study. Using an in vitro assay the compounds were evaluated for their ability to inhibit VEGF-induced angiogenesis in HUVECs, and the cytotoxicity of representative compounds was also studied in tumour cell lines using 24-h exposure. The results indicate that the SU compounds, SU1433, SU 5416 and SU6668, are more potent inhibitors of VEGF-induced angiogenesis than indomethacin or the naturally occurring biochanin A, presumably because they inhibit VEGF receptor signalling. Blocking one of the phenolic OH groups of SU1433 reduced anti-angiogenic activity, as did blocking the NH groups of SU5416 and SU6668. Cytotoxicity studies indicate that none of the compounds examined exhibited cytotoxicity at anti-angiogenic concentrations.
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Abstract
The transbilayer distribution of phospholipids in plasma membrane vesicles derived from BHK cells by treatment with iodoacetamide or fluoride and merocyanine 540 has been examined by exposing the vesicles to bee venom phospholipase A2 (PLA2) or to Bacillus cereus sphingomyelinase. The results show that almost all of the phosphatidylserine (PS) is on the inner lipid leaflet and most of the sphingomyelin is on the outer lipid leaflet. In contrast, about 50% of the phosphatidylcholine (PC) and 30-40% of the phosphatidylethanolamine (PE) is rapidly degraded by PLA2 and thus appears to be present on the surface of the vesicles. The pools of PC and PE which are accessible only slowly to PLA2 are degraded with halftimes of about 5 h and 2 h, respectively, and it is suggested that this rate reflects the rate of transbilayer migration of these lipids. We conclude that the profound energy depletion caused by treatment with iodoacetamide or fluoride does not alter the asymmetric distribution of PS across the plasma membrane but does have a marked effect on the transbilayer distribution of PE. Residual cells after treatment with fluoride and MC540 were also exposed to PLA2. The results were broadly in agreement with those obtained with vesicles, suggesting that the vesicles were representative of the BHK cell plasma membrane in terms of phospholipid asymmetry. Fluoride or MC540 added separately caused little vesicle release but did lead to significant loss of phospholipid asymmetry. When centrifuged on a sucrose density gradient, vesicles were separated into two major fractions accounting for about two thirds and about 20%, respectively, of total phospholipid but no significant differences were seen in the transbilayer phospholipid asymmetry of the two fractions.
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Affiliation(s)
- J L Whatmore
- Department of Physiology, University College London, UK
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Abstract
An analysis was made of the rate, extent, and reversibility of the morphological transitions which were induced in human erythrocytes after loading with 150 microM or 1 mM Ca2+. The rate and extent of proteolytic cleavage of cytoskeletal proteins were monitored simultaneously, particularly those of the ankyrins and band 4.1, and were found not to reflect the rate of shape change. These observations were made when intact cells were incubated either in a buffer which supported glycolysis or in a simple isotonic Tris buffer without glucose. The composition of the buffer affected the initial morphology of the cells, the rate of morphological transition, the rate of proteolysis of cytoskeletal proteins, and the extent and kinetics of the reversal of morphology from the echinocyte to discocyte after removal of the ionophore A23187 and Ca2+. The morphology of cells transformed to spheroechinocytes by loading metabolically depleted cells for 15 min with 1 mM Ca2+, and which retained 50% band 2.1, was reversed in the presence of substrates for ATP synthesis to that of a mixture of 60% stage 1 echinocytes plus 25% discocytes, suggesting that ankyrin may not be essential for the maintenance of a disc-like morphology. Echinocytes which were depleted of greater than 50% band 4.1 were unable to undergo the transition back to discs.
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Affiliation(s)
- J L Whatmore
- Pharmaceutical Sciences Institute, Aston University, Birmingham, United Kingdom
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