Publications
131 results found
Mazi SI, Ahmetaj-Shala B, Warner TD, et al., 2019, Omic profiling in healthy volunteers taking celecoxib reveals novel biomarkers regulated by cyclooxygenase-2, British-Pharmacology-Society Meeting (Pharmacology), Publisher: WILEY, Pages: 1628-1628, ISSN: 0306-5251
Akhmedov D, Kirkby NS, Mitchell JA, et al., 2019, Imaging of Tissue-Specific and Temporal Activation of GPCR Signaling Using DREADD Knock-In Mice., Pages: 361-376
Engineered G protein-coupled receptors (DREADDs, designer receptors exclusively activated by designer drugs) are convenient tools for specific activation of GPCR signaling in many cell types. DREADDs have been utilized as research tools to study numerous cellular and physiologic processes, including regulation of neuronal activity, behavior, and metabolism. Mice with random insertion transgenes and adeno-associated viruses have been widely used to express DREADDs in individual cell types. We recently created and characterized ROSA26-GsDREADD knock-in mice to allow Cre recombinase-dependent expression of a Gαs-coupled DREADD (GsD) fused to GFP in distinct cell populations in vivo. These animals also harbor a CREB-activated luciferase reporter gene for analysis of CREB activity by in vivo imaging, ex vivo imaging, or biochemical reporter assays. In this chapter, we provide detailed methods for breeding GsD animals, inducing GsD expression, stimulating GsD activity, and measuring basal and stimulated CREB reporter bioluminescence in tissues in vivo, ex vivo, and in vitro. These animals are available from our laboratory for non-profit research.
Mitchell J, Kirkby NS, 2019, Eicosanoids, prostacyclin and cyclooxygenase in the cardiovascular system, British Journal of Pharmacology, Vol: 176, Pages: 1038-1050, ISSN: 1476-5381
Eicosanoids represent a diverse family of lipid mediators with fundamental roles in controlling physiology and disease. Within the eicosanoid super family are prostanoids, which are specifically derived from arachidonic acid by the enzyme cyclooxygenase(COX). COX has two isoforms; COX-1 and COX-2. COX-2 is the therapeutic target for the nonsteroidal anti-inflammatory drug (NSAID) class of pain medications. Of the prostanoids,prostacyclin, first discovered by Sir Professor John Vane in 1976,remains amongst the best studied and retains an impressive pedigree as onethe bodies fundamental cardiovascular protective pathways. Since this time, we have learnt much about how eicosanoids, COXenzymes and prostacyclin function in the cardiovascular system which has allowed us to, for example, harness the power of prostacyclin as therapy to treat pulmonary arterial hypertension and peripheral vascular disease. However, there remain many unanswered questions in our basic understanding of the pathways and how they can be usedto improve human health. Perhaps the most importantand controversial outstanding question in the field remains;‘how do NSAIDsproduce their much publicized cardiovascular side effects?’This review summarises the history, biology and cardiovascular function of key eicosanoids with particular focus on prostacyclin and other COXproducts and discusses how our knowledge of these pathways can applied in future drug discovery and be used to explain the cardiovascular side effects of NSAIDs.
Mitchell JA, Shala F, Elghazouli Y, et al., 2018, Renal or Vascular Deletion of COX-2 Increases Thrombotic Tone: Relevance to Cardiovascular Side Effects of Non-Steroidal Anti-Inflammatory Drugs, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Kirkby NS, Akhmedov D, Shala F, et al., 2018, The Right Heart is Specifically Targeted by Intravenous Administration of Treprostinil: Implications for Our Understanding of How Prostacyclin Drugs Work to Treat Pulmonary Arterial Hypertension, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Kirkby NS, Akhmedov D, Berdeaux R, et al., 2018, Bioluminescent Imaging of Tissue From Creb Reporter Mice Reveals the Endothelium as the Principle Site of Vascular Prostacyclin Sensing, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Mitchell JA, Shala F, Elghazouli Y, et al., 2018, Systemic Anti-Thrombotic Protection by a Non-Endothelial COX-1 / Prostacyclin Pathway, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Kawai R, Ahmetaj-Shala B, Shih CC, et al., 2018, Development of a human autologous 3-cell cytokine release assay that models the vascular wall <i>in vitro</i>, 54th Congress of the European-Societies-of-Toxicology (EUROTOX) - Toxicology Out of the Box, Publisher: ELSEVIER IRELAND LTD, Pages: S114-S114, ISSN: 0378-4274
Ahmetaj-Shala B, Olanipekun M, Tesfai A, et al., 2018, Development of a novel UPLC-MS/MS-based platform to quantify amines, amino acids and methylarginines for applications in human disease phenotyping, Scientific Reports, Vol: 8, ISSN: 2045-2322
Amine quantification is an important strategy in patient stratification and personalised medicine. This is because amines, including amino acids and methylarginines impact on many homeostatic processes. One important pathway regulated by amine levels is nitric oxide synthase (NOS). NOS is regulated by levels of (i) the substrate, arginine, (ii) amino acids which cycle with arginine and (iii) methylarginine inhibitors of NOS. However, biomarker research in this area is hindered by the lack of a unified analytical platform. Thus, the development of a common metabolomics platform, where a wide range of amino acids and methylarginines can be measured constitutes an important unmet need. Here we report a novel high-throughput ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) platform where ≈40 amine analytes, including arginine and methylarginines can be detected and quantified on a molar basis, in a single sample of human plasma. To validate the platform and to generate biomarkers, human plasma from a well-defined cohort of patients before and after coronary artery bypass surgery, who developed systemic inflammatory response syndrome (SIRS), were analysed. Bypass surgery with SIRS significantly altered 26 amine analytes, including arginine and ADMA. Consequently, pathway analysis revealed significant changes in a range of pathways including those associated with NOS.
Mitchell JA, Knowles RB, Kirkby NS, et al., 2018, Letter by Mitchell et al Regarding Article, "Urinary Prostaglandin Metabolites: An Incomplete Reckoning and a Flush to Judgment"., Circulation Research, Vol: 122, Pages: e84-e85, ISSN: 0009-7330
Mitchell JA, Knowles RB, Kirkby NS, et al., 2018, Kidney transplantation in a patient lacking cytosolic phospholipase A2Proves renal origins of urinary PGI-M and TX-M, Circulation Research, Vol: 122, Pages: 555-559, ISSN: 0009-7330
RATIONALE: The balance between vascular prostacyclin, which is antithrombotic, and platelet thromboxane A2, which is prothrombotic, is fundamental to cardiovascular health. Prostacyclin and thromboxane A2are formed after the concerted actions of cPLA2α (cytosolic phospholipase A2) and COX (cyclooxygenase). Urinary 2,3-dinor-6-keto-PGF1α(PGI-M) and 11-dehydro-TXB2(TX-M) have been taken as biomarkers of prostacyclin and thromboxane A2formation within the circulation and used to explain COX biology and patient phenotypes, despite concerns that urinary PGI-M and TX-M originate in the kidney. OBJECTIVE: We report data from a remarkable patient carrying an extremely rare genetic mutation in cPLA2α, causing almost complete loss of prostacyclin and thromboxane A2, who was transplanted with a normal kidney resulting in an experimental scenario of whole-body cPLA2α knockout, kidney-specific knockin. By studying this patient, we can determine definitively the contribution of the kidney to the productions of PGI-M and TX-M and test their validity as markers of prostacyclin and thromboxane A2in the circulation. METHODS AND RESULTS: Metabolites were measured using liquid chromatography-tandem mass spectrometry. Endothelial cells were grown from blood progenitors. Before kidney transplantation, the patient's endothelial cells and platelets released negligible levels of prostacyclin (measured as 6-keto-prostaglandin F1α) and thromboxane A2(measured as TXB2), respectively. Likewise, the urinary levels of PGI-M and TX-M were very low. After transplantation and the establishment of normal renal function, the levels of PGI-M and TX-M in the patient's urine rose to within normal ranges, whereas endothelial production of prostacyclin and platelet production of thromboxane A2remained negligible. CONCLUSIONS: These data show that PGI-M and TX-M can be derived exclusively from the kidney without contribution from prostacyclin made by endothelial cells or thromb
Kirkby NS, Sampaio W, Etelvino G, et al., 2018, Cyclooxygenase-2 selectively controls renal blood flow through a novel PPARβ/δ-dependent renal vasodilator pathway, Hypertension, Vol: 71, Pages: 297-305, ISSN: 0194-911X
Cyclooxygenase-2 (COX-2) is an inducible enzyme expressed in inflammation and cancer targeted by nonsteroidal anti-inflammatory drugs. COX-2 is also expressed constitutively in discreet locations where its inhibition drives gastrointestinal and cardiovascular/renal side effects. Constitutive COX-2 expression in the kidney regulates renal function and blood flow; however, the global relevance of the kidney versus other tissues to COX-2–dependent blood flow regulation is not known. Here, we used a microsphere deposition technique and pharmacological COX-2 inhibition to map the contribution of COX-2 to regional blood flow in mice and compared this to COX-2 expression patterns using luciferase reporter mice. Across all tissues studied, COX-2 inhibition altered blood flow predominantly in the kidney, with some effects also seen in the spleen, adipose, and testes. Of these sites, only the kidney displayed appreciable local COX-2 expression. As the main site where COX-2 regulates blood flow, we next analyzed the pathways involved in kidney vascular responses using a novel technique of video imaging small arteries in living tissue slices. We found that the protective effect of COX-2 on renal vascular function was associated with prostacyclin signaling through PPARβ/δ (peroxisome proliferator-activated receptor-β/δ). These data demonstrate the kidney as the principle site in the body where local COX-2 controls blood flow and identifies a previously unreported PPARβ/δ-mediated renal vasodilator pathway as the mechanism. These findings have direct relevance to the renal and cardiovascular side effects of drugs that inhibit COX-2, as well as the potential of the COX-2/prostacyclin/PPARβ/δ axis as a therapeutic target in renal disease.
Lee S-Y, Chang W-L, Li Z-X, et al., 2018, Astragaloside VI and cycloastragenol-6-O-beta-D-glucoside promote wound healing in vitro and in vivo, PHYTOMEDICINE, Vol: 38, Pages: 183-191, ISSN: 0944-7113
BackgroundAstragalus genus includes most of the common, historical herbal medicines that have various applications in Asian countries. However, clinical data and mechanistic insights into their actions are still lacking.PurposeIn this study, we aimed to examine the effects of astragalosides on wound healing in vitro and in vivo, as well as the underlying mechanisms of these actions.MethodsThe wound healing activity of astragalosides was investigated in human HaCaT keratinocytes, human dermal fibroblast (HDF) cells, and murine models of wound healing.ResultsAll eight astragalosides studied enhanced epidermal growth factor receptor (EGFR) activity in HaCaT cells. Among them, astragaloside VI (AS-VI) showed the strongest EGFR activation. Consistently, AS-VI and cycloastragenol-6-O-beta-D-glucoside (CMG), which is the major metabolite of astragalosides, enhanced extracellular signal-regulated kinase (ERK) activity in a concentration-dependent manner. In agreement, both compounds induced EGFR-dependent cell proliferation and migration in HaCaT and HDF cells. In addition, we showed that AS-VI and CMG accelerated the healing of both sterile and infected wounds in vivo. These effects were associated with increased angiogenesis in the scar tissue.ConclusionAS-VI and CMG increased the proliferation and migration of skin cells via activation of the EGFR/ERK signalling pathway, resulting in the improvement of wound healing in vitro and in vivo. These findings indicate the therapeutic potential of AS-VI and CMG to accelerate wound healing; additionally, they suggest the mechanistic basis of this activity.
Mitchell JA, Shala F, Ahmetaj-Shala B, et al., 2017, Novel Tissue-specific Cyclooxygenase-1 Knockout Mice Demonstrate a Dominant Role for Endothelial Cyclooxygenase-1 in Prostacyclin Production, Scientific Sessions of the American-Heart-Association / Resuscitation Science Symposium, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Kirkby NS, Morris AP, Lytton J, et al., 2017, Genome-Wide Association Study Links Variants With Occurrence of Cardiovascular Events in People Taking the COX-2 Inhibitor Celecoxib: Identification of NCKX2 as a Novel Protective Pathway in Renal Vessels, Scientific Sessions of the American-Heart-Association / Resuscitation Science Symposium, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
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Kirkby NS, Jiao J, Herschman HR, et al., 2017, Production of High Levels of PGI-M in the Kidney and Bladder Explains the Renal Origin of Urinary Markers of Prostacyclin, Scientific Sessions of the American-Heart-Association / Resuscitation Science Symposium, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
Mitchell JA, Benson J, Shala F, et al., 2017, Vascular Prostanoids Paradoxically Amplify Vasoconstriction During Platelet Activation, Scientific Sessions of the American-Heart-Association / Resuscitation Science Symposium, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
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Lee S-Y, Chen P-Y, Lin J-C, et al., 2017, Melaleuca alternifolia Induces Heme Oxygenase-1 Expression in Murine RAW264.7 Cells through Activation of the Nrf2-ARE Pathway, AMERICAN JOURNAL OF CHINESE MEDICINE, Vol: 45, Pages: 1631-1648, ISSN: 0192-415X
Melaleuca alternifolia concentrate (MAC) is the refined essential oil of the Australian native plant Melaleuca alternifolia. MAC has been reported to suppress the production of pro-inflammatory cytokines in both murine RAW264.7 macrophages and human monocytes stimulated with lipopolysaccharide (LPS). However, the mechanisms involved in this effect remain unclear. This study aims to delineate the molecular mechanisms that drive the anti-inflammatory activity of MAC and its active component, terpinen-4-ol, in macrophages. The effects of MAC on RAW264.7 cells were studied using western blotting, real-time PCR, an electrophoretic mobility shift assay (EMSA), and NF-κB luciferase reporter assays. Our results showed that MAC significantly increased both the mRNA and protein levels of heme oxygenase-1 (HO-1) via p38 and JNK MAPK activation. In addition, we showed that MAC significantly increased the activation and nuclear translocation of NF-E2-related factor 2 (Nrf2), a key transcription factor regulating HO-1 induction. MAC was also associated with significant inhibition of iNOS expression, NO production, and NF-κB activation. HO-1 was required for these anti-inflammatory effects as tin protoporphyrin IX (SnPPIX), an HO-1 inhibitor, abolished the effects of MAC on LPS-induced iNOS, NO, and NF-κB activation. Our results indicate that MAC induces HO-1 expression in murine macrophages via the p38 MAPK and JNK pathways and that this induction is required for its anti-inflammatory activity.
Slingsby MHL, Nyberg M, Egelund J, et al., 2017, Aerobic exercise training lowers platelet reactivity and improves platelet sensitivity to prostacyclin in pre- and postmenopausal women, Journal of Thrombosis and Haemostasis, Vol: 15, Pages: 2419-2431, ISSN: 1538-7836
BackgroundThe risk of atherothrombotic events increases after the menopause. Regular physical activity has been shown to reduce platelet reactivity in younger women, but it is unknown how regular exercise affects platelet function after the menopause.ObjectivesTo examine the effects of regular aerobic exercise in late premenopausal and recent postmenopausal women by testing basal platelet reactivity and platelet sensitivity to prostacyclin and nitric oxide.MethodsTwenty-five sedentary, but healthy, late premenopausal and 24 matched recently postmenopausal women, mean (95% confidence interval) 49.1 (48.2–49.9) and 53.7 (52.5–55.0) years old, participated in an intervention study: 3-month high-intensity supervised aerobic spinning-cycle training (1 h, × 3/week). Basal platelet reactivity was analyzed in platelet-rich plasma from venous blood as agonist-induced % aggregation. In a subgroup of 13 premenopausal and 14 postmenopausal women, platelet reactivity was tested ex vivo after femoral arterial infusion of prostacyclin, acetylcholine, a cyclooxygenase inhibitor, and after acute one-leg knee extensor exercise.ResultsBasal platelet reactivity (%aggregation) to TRAP-6 (1 μm) was higher in the postmenopausal, 59% (50–68), than the premenopausal women, 45% (35–55). Exercise training reduced basal platelet reactivity to collagen (1 μg mL−1) in the premenopausal women only: from 63% (55–71%) to 51% (41–62%). After the training intervention, platelet aggregation was more inhibited by the arterial prostacyclin infusion and the acute exercise in both premenopausal and postmenopausal women.ConclusionsThese results highlight previously unknown cardioprotective aspects of regular aerobic exercise in premenopausal and postmenopausal women, improving their regulation of platelet reactivity through an increased platelet sensitivity to prostacyclin, which may counterbalance the increased atherothrombotic risk associated with the
Tesfai A, MacCallum N, Kirkby NS, et al., 2017, Metabolomic profiling of amines in sepsis predicts changes in NOS canonical pathways, PLoS ONE, Vol: 12, ISSN: 1932-6203
RationaleNitric oxide synthase (NOS) is a biomarker/target in sepsis. NOS activity is driven by amino acids, which cycle to regulate the substrate L-arginine in parallel with cycles which regulate the endogenous inhibitors ADMA and L-NMMA. The relationship between amines and the consequence of plasma changes on iNOS activity in early sepsis is not known.ObjectiveOur objective was to apply a metabolomics approach to determine the influence of sepsis on a full array of amines and what consequence these changes may have on predicted iNOS activity.Methods and measurements34 amino acids were measured using ultra purification mass spectrometry in the plasma of septic patients (n = 38) taken at the time of diagnosis and 24–72 hours post diagnosis and of healthy volunteers (n = 21). L-arginine and methylarginines were measured using liquid-chromatography mass spectrometry and ELISA. A top down approach was also taken to examine the most changed metabolic pathways by Ingenuity Pathway Analysis. The iNOS supporting capacity of plasma was determined using a mouse macrophage cell-based bioassay.Main resultsOf all the amines measured 22, including L-arginine and ADMA, displayed significant differences in samples from patients with sepsis. The functional consequence of increased ADMA and decreased L-arginine in context of all cumulative metabolic changes in plasma resulted in reduced iNOS supporting activity associated with sepsis.ConclusionsIn early sepsis profound changes in amine levels were defined by dominant changes in the iNOS canonical pathway resulting in functionally meaningful changes in the ability of plasma to regulate iNOS activity ex vivo.
Mohamed NA, Davies RP, Lickiss PD, et al., 2017, Chemical and biological assessment of metal organic frameworks (MOFs) in pulmonary cells and in an acute in vivo model: relevance to pulmonary arterial hypertension therapy, Pulmonary Circulation, Vol: 7, Pages: 1-11, ISSN: 2045-8940
Pulmonary arterial hypertension (PAH) is a progressive and debilitating condition. Despite promoting vasodilation, current drugs have a therapeutic window within which they are limited by systemic side effects. Nanomedicine uses nanoparticles to improve drug delivery and/or reduce side effects. We hypothesize that this approach could be used to deliver PAH drugs avoiding the systemic circulation. Here we report the use of iron metal organic framework (MOF) MIL-89 and PEGylated MIL-89 (MIL-89 PEG) as suitable carriers for PAH drugs. We assessed their effects on viability and inflammatory responses in a wide range of lung cells including endothelial cells grown from blood of donors with/without PAH. Both MOFs conformed to the predicted structures with MIL-89 PEG being more stable at room temperature. At concentrations up to 10 or 30 µg/mL, toxicity was only seen in pulmonary artery smooth muscle cells where both MOFs reduced cell viability and CXCL8 release. In endothelial cells from both control donors and PAH patients, both preparations inhibited the release of CXCL8 and endothelin-1 and in macrophages inhibited inducible nitric oxide synthase activity. Finally, MIL-89 was well-tolerated and accumulated in the rat lungs when given in vivo. Thus, the prototypes MIL-89 and MIL-89 PEG with core capacity suitable to accommodate PAH drugs are relatively non-toxic and may have the added advantage of being anti-inflammatory and reducing the release of endothelin-1. These data are consistent with the idea that these materials may not only be useful as drug carriers in PAH but also offer some therapeutic benefit in their own right.
Crescente M, Armstrong PC, Chan MV, et al., 2017, PLATELET COX-1 KNOCKOUT MOUSE AS A MODEL OF THE EFFECTS OF ASPIRIN IN THE CARDIOVASCULAR SYSTEM, Annual Conference of the British-Cardiovascular-Society (BCS), Publisher: BMJ PUBLISHING GROUP, Pages: A108-A109, ISSN: 1355-6037
Parzych K, Zetterqvist A, Wright WR, et al., 2017, Differential role of the pannexin-1/ATP/P2X7 axis in IL-1β release by human monocytes, The FASEB Journal, Vol: 31, Pages: 2439-2445, ISSN: 0892-6638
IL-1βrelease is integral to the innateimmune system. The release of mature IL-1β depends on two regulated events; (i) the denovoinduction of pro-IL-1β, generally via NFκB-dependenttransduction pathwaysand (ii) the assembly and activation of the NLRP3 inflammasome. This latter step is reliant on active capase-1, pannexin-1 and P2X7receptor activation. Pathogen associated molecular patterns in Gram-positive and Gram-negative bacteria activate IL-1β release from immune cells via TLR2 and TLR4 receptors respectively. Here,we show that pro-IL-1β and mature IL-1β release from human monocytes is stimulated by the TLR2 agonists,Pam3CSK4 or FSL-1,and the TLR4 agonist,LPS, in the absence of additional ATP. TLR2 agonists required pannexin-1 and P2X7receptor activationto stimulate IL-1βrelease. By contrast, IL-1β release stimulated by the TLR4 agonist,LPS,is independent of both pannexin-1 and P2X7activation. In the absence of exogenous ATP,P2X7activation requires endogenous ATP release, which occurs in some cells via pannexin-1. In line with this,we found that LPS-stimulated human monocytes released relatively low levels of ATP,whereas cells stimulated with TLR2 agonists released high levels of ATP. These findings suggest that,in human monocytes, TLR2 and TLR4 signalling bothinduce pro-IL-1β expression,but the mechanism by which they activate caspase-1 diverges at the level of the pannexin-1/ATP/P2X7axis.
Ahmetaj-Shala B, Tesfai A, Constantinou C, et al., 2017, Pharmacological assessment of ibuprofen arginate on platelet aggregation and colon cancer cell killing, Biochemical and Biophysical Research Communications, Vol: 484, Pages: 762-766, ISSN: 1090-2104
Nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen, are amongst the most commonly used medications and produce their anti-inflammatory and analgesic benefits by blocking cyclooxygenase (COX)-2. These drugs also have the potential to prevent and treat cancer and some members of the class including ibuprofen can produce anti-platelet effects. Despite their utility, all NSAIDs are associated with increased risk of cardiovascular side effects which our recent work suggests could be mediated by increased levels of the endogenous NO synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) leading to reduced endothelial NOS activity and associated endothelial cell dysfunction. ADMA is a cardiotoxic hormone and biomarker of cardiovascular risk whose effects can be prevented by l-arginine. The ibuprofen salt, ibuprofen arginate (Spididol®) was created to increase drug solubility but we have previously established that it not only effectively blocks COX-2 but also provides an arginine source able to reverse the effects of ADMA in vitro and in vivo. Here we have gone on to explore whether the formulation of ibuprofen with arginine influences the potency and efficacy of the parent molecule using a range of simple in vitro assays designed to test the effects of NSAIDs on (i) platelet aggregation and (iii) colon cancer cell killing. Our findings demonstrate that ibuprofen arginate retains these key functional effects of NSAIDs with similar or increased potency compared to ibuprofen sodium, further illustrating the potential of ibuprofen arginate as an efficacious drug with the possibility of improved cardiovascular safety.
Tesfai A, Shala BA, Shala F, et al., 2017, Plasma Taurine Levels At Early Diagnosis Predict Survival, International Conference of the American-Thoracic-Society (ATS), Publisher: AMER THORACIC SOC, ISSN: 1073-449X
Miller E, Czopek A, Duthie KM, et al., 2016, Smooth muscle endothelin B receptors regulate blood pressure but not vascular function or neointimal remodeling, Hypertension, Vol: 69, Pages: 275-285, ISSN: 1524-4563
The role of smooth muscle endothelinB (ETB) receptors in regulating vascular function, blood pressure (BP), and neointimal remodeling has not been established. Selective knockout mice were generated to address the hypothesis that loss of smooth muscle ETB receptors would reduce BP, alter vascular contractility, and inhibit neointimal remodeling. ETB receptors were selectively deleted from smooth muscle by crossing floxed ETB mice with those expressing cre-recombinase controlled by the transgelin promoter. Functional consequences of ETB deletion were assessed using myography. BP was measured by telemetry, and neointimal lesion formation induced by femoral artery injury. Lesion size and composition (day 28) were analyzed using optical projection tomography, histology, and immunohistochemistry. Selective deletion of ETB was confirmed by genotyping, autoradiography, polymerase chain reaction, and immunohistochemistry. ETB-mediated contraction was reduced in trachea, but abolished from mesenteric veins, of knockout mice. Induction of ETB-mediated contraction in mesenteric arteries was also abolished in these mice. Femoral artery function was unaltered, and baseline BP modestly elevated in smooth muscle ETB knockout compared with controls (+4.2±0.2 mm Hg; P<0.0001), but salt-induced and ETB blockade–mediated hypertension were unaltered. Circulating endothelin-1 was not altered in knockout mice. ETB-mediated contraction was not induced in femoral arteries by incubation in culture medium or lesion formation, and lesion size was not altered in smooth muscle ETB knockout mice. In the absence of other pathology, ETB receptors in vascular smooth muscle make a small but significant contribution to ETB-dependent regulation of BP. These ETB receptors have no effect on vascular contraction or neointimal remodeling.
Ingles M, Crowfoot G, Smelaya TV, et al., 2016, Sepsis 2016 Paris, ISSN: 1364-8535
Mitchell JA, Knowles R, Kirkby NS, et al., 2016, Kidney Transplantation in a Patient Lacking Cytosolic Phospholipase A<sub>2</sub> Leads to Urinary Prostacyclin and Thromboxane A<sub>2</sub> Metabolites Within Normal Ranges, Scientific Sessions of the American-Heart-Association / Resuscitation Science Symposium, Publisher: LIPPINCOTT WILLIAMS & WILKINS, ISSN: 0009-7322
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Rauzi F, Kirkby NS, Edin ML, et al., 2016, Aspirin inhibits the production of proangiogenic 15(S)-HETE by platelet cyclooxygenase-1, Faseb Journal, Vol: 30, Pages: 4256-4266, ISSN: 1530-6860
Regular consumption of low-dose aspirin reduces the occurrence of colorectal, esophageal, stomach, and gastrointestinal cancers. The underlying mechanism is unknown but may be linked to inhibition of angiogenesis. Because the effective doses of aspirin are consistent with the inhibition of cyclooxygenase-1 in platelets, we used liquid chromatography with tandem mass spectrometry analyses and immunoassays of human platelet releasates coupled with angiogenesis assays to search for the mediator(s) of these effects. Blood or platelet-rich plasma from healthy volunteers stimulated with platelet activators produced a broad range of eicosanoids. Notably, preincubation of platelets with aspirin, but not with a P2Y12 receptor antagonist, caused a marked reduction in the production of 11-hydroxyeicosatetraenoic acid (HETE) and 15(S)-HETE, in addition to prostanoids such as thromboxane A2 Releasates from activated platelets caused cell migration and tube formation in cultured human endothelial cells and stimulated the sprouting of rat aortic rings in culture. These proangiogenic effects were absent when platelets were treated with aspirin but returned by coincubation with exogenous 15(S)-HETE. These results reveal 15(S)-HETE as a major platelet cyclooxygenase-1 product with strong proangiogenic effects. Thus, 15(S)-HETE represents a potential target for the development of novel antiangiogenic therapeutics, and blockade of its production may provide a mechanism for the anticancer effects of aspirin.-Rauzi, F., Kirkby, N. S., Edin, M. L., Whiteford, J. Zeldin, D. C., Mitchell, J. A., Warner, T. D. Aspirin inhibits the production of proangiogenic 15(S)-HETE by platelet cyclooxygenase-1.
Mohamed NA, Ahmetaj-Shala B, Duluc L, et al., 2016, A New NO-Releasing Nanoformulation for the Treatment of Pulmonary Arterial Hypertension., Journal of Cardiovascular Translational Research, Vol: 9, Pages: 162-164, ISSN: 1937-5395
Pulmonary arterial hypertension (PAH) is a chronic and progressive disease which continues to carry an unacceptably high mortality and morbidity. The nitric oxide (NO) pathway has been implicated in the pathophysiology and progression of the disease. Its extremely short half-life and systemic effects have hampered the clinical use of NO in PAH. In an attempt to circumvent these major limitations, we have developed a new NO-nanomedicine formulation. The formulation was based on hydrogel-like polymeric composite NO-releasing nanoparticles (NO-RP). The kinetics of NO release from the NO-RP showed a peak at about 120 min followed by a sustained release for over 8 h. The NO-RP did not affect the viability or inflammation responses of endothelial cells. The NO-RP produced concentration-dependent relaxations of pulmonary arteries in mice with PAH induced by hypoxia. In conclusion, NO-RP drugs could considerably enhance the therapeutic potential of NO therapy for PAH.
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