Imperial College London

ProfessorJaneMitchell

Faculty of MedicineNational Heart & Lung Institute

Professor of Pharmacology in Critical Care Medicine
 
 
 
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Contact

 

+44 (0)20 7351 8137j.a.mitchell

 
 
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Location

 

Guy Scadding BuildingRoyal Brompton Campus

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Summary

 

Publications

Publication Type
Year
to

389 results found

Mitchell J, Shala F, Elghazouli Y, Warner T, Gaston-Massuet C, Crescente M, Armstrong P, Herschman H, Kirkby Net al., Cell-specific gene deletion reveals the anti-thrombotic function of COX1 and explains the vascular COX1/prostacyclin paradox, Circulation Research, ISSN: 0009-7330

Journal article

Marei I, Mongey R, Gashaw H, Mitchell JAet al., 2019, Isolation of blood outgrowth endothelial cells under shear conditions: A move towards a more physiological vascular cell platform, British-Pharmacology-Society Meeting (Pharmacology), Publisher: WILEY, Pages: 3033-3033, ISSN: 0007-1188

Conference paper

Ahmetaj-Shala B, Kawai R, Marei I, Bhatti F, Gashaw H, Kirkby NS, Mitchell JAet al., 2019, A bioassay system of autologous human endothelial and smooth muscle cells for use in cardiovascular drug discovery and patient phenotyping, British-Pharmacology-Society Meeting (Pharmacology), Publisher: WILEY, Pages: 3040-3041, ISSN: 0007-1188

Conference paper

Mohamed NA, Davies RP, Lickiss PD, Kameno Y, Marei I, Kirkby NS, Mitchell JA, Abou Saleh Het al., 2019, Mil-89 nanoformulation as a platform to improve pulmonary arterial hypertension treatment, British-Pharmacology-Society Meeting (Pharmacology), Publisher: WILEY, Pages: 3075-3075, ISSN: 0007-1188

Conference paper

Marei I, Al Shammari H, Latif N, Ahmetaj-Shala B, Yacoub MH, Chester AH, Mitchell JAet al., 2019, Effect of toll-like receptor antagonists on side specific aortic valve endothelial cells, British-Pharmacology-Society Meeting (Pharmacology), Publisher: WILEY, Pages: 2999-3000, ISSN: 0007-1188

Conference paper

Mazi SI, Ahmetaj-Shala B, Warner TD, Mitchell JA, Kirkby NSet 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

Conference paper

Ciano M, Mantellato G, Connolly M, Paul-Clark M, Mitchell J, Wilson-Owen S, Cookson W, Moffatt M, Hughes S, Polkey M, Kemp P, Natanek Set al., EGF receptor (EGFR) inhibition promotes a slow-twitch oxidative, over a fast-twitch, muscle phenotype, Scientific Reports, ISSN: 2045-2322

A low quadriceps slow-twitch (ST), oxidative (relative to fast-twitch) fiber proportion is prevalent in chronic diseases such Chronic Obstructive Pulmonary Disease (COPD) and is associated with exercise limitation and poor outcomes. Benefits of an increased ST fiber proportion are demonstrated in genetically modified animals. Pathway analysis of published data of differentially expressed genes in mouse ST and FT fibers, mining of our microarray data and a qPCR analysis of quadriceps specimens from COPD patients and controls were performed. ST markers were quantified in C2C12 myotubes with EGF-neutralizing antibody, EGFR inhibitor or an EGFR-silencing RNA added. A zebrafish egfra mutant was generated by genome editing and ST fibers counted. EGF signaling was (negatively) associated with the ST muscle phenotype in mice and humans, and muscle EGF transcript levels were raised in COPD. In C2C12 myotubes, EGFR inhibition/silencing increased ST, including mitochondrial, markers. In zebrafish, egfra depletion increased ST fibers and mitochondrial content. EGF is negatively associated with ST muscle phenotype in mice, healthy humans and COPD patients. EGFR blockade promotes the ST phenotype in myotubes and zebrafish embryos. EGF signaling suppresses the ST phenotype, therefore EGFR inhibitors may be potential treatments for COPD-related muscle ST fiber loss.

Journal article

Lucotti S, Cerutti C, Soyer M, Gil-Bernabe AM, Gomes AL, Allen PD, Smart S, Markelc B, Watson K, Armstrong PC, Mitchell JA, Warner TD, Ridley AJ, Muschel RJet al., 2019, Aspirin blocks formation of metastatic intravascular niches by inhibiting platelet-derived COX-1/thromboxane A(2), JOURNAL OF CLINICAL INVESTIGATION, Vol: 129, Pages: 1845-1862, ISSN: 0021-9738

Journal article

Akhmedov D, Kirkby NS, Mitchell JA, Berdeaux Ret 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.

Book chapter

Alvarez-Fuente M, Moreno L, Mitchell JA, Reiss IK, Lopez P, Elorza D, Duijts L, Avila-Alvarez A, Arruza L, Ramirez Orellana M, Baraldi E, Zaramella P, Rueda S, Gimeno-Diaz de Atauri A, Guimaraes H, Rocha G, Proenca E, Thebaud B, Jesus del Cerro Met al., 2019, Preventing bronchopulmonary dysplasia: new tools for an old challenge, PEDIATRIC RESEARCH, Vol: 85, Pages: 432-441, ISSN: 0031-3998

Journal article

Mitchell JA, Bishop-Bailey D, 2019, PPARβ/δ a potential target in pulmonary hypertension blighted by cancer risk, Pulmonary Circulation, Vol: 9, Pages: 1-2, ISSN: 2045-8940

Journal article

Mitchell J, Bishop-Bailey D, PPARβ/δ a potential target in pulmonary hypertension blighted by cancer risk., Pulmonary Circulation, ISSN: 2045-8940

Dear Editor,Our group and others have used preclinical in vitro and in vivo models that highlight the potential therapeutic benefit of PPARβ/δ as a target in the treatment of pulmonary arterial hypertension. Selective agonists of PPARβ/δ inhibit fibroblast and pulmonary arterial vascular smooth muscle cell growth and prevent right heart hypertrophy in rat models of pulmonary arterial hypertension. Further work published in Pulmonary Circulation established the transcriptomic profile and pathways associated with activating PPARβ/δ in a model of pulmonary artery banding and right heart hypertrophy (1). These results and the fact that enhancing PPARβ/δ is linked to increased endurance exercise performance (2) supports the idea that drugs working on this pathway could be beneficial in pulmonary arterial hypertension. However, there is cause for concern regarding at least one drug that activates PPARβ/δ, GW501516, developed by GlaxoSmithKline plc (GSK) in the early 2000’s. Despite these concerns and although not confirmed in humans, following the publication of endurance exercise studies in rodents, a significant underground market has developed for unlicensed GW501516 (also referred to as Endurobol or Cardarine) in a bid to enhance human athletic performance. PPARβ/δ agonists, including GW501516 were developed for the treatment of hyperlipidemia and other cardiovascular diseases and a number of clinical trails have been registered on clinicaltrials.gov (Clinical trials id NCT00388180; NCT00318617; NCT00158899; NCT00841217). Whilst, long term clinical data are not available, GW501516 improved lipid profiles in short term studies in man (3-5). However safety concerns over GW501516 and potentially other drugs in the class have emerged. Of particular relevance are two abstracts from GSK showing that GW501516 causes cancer in rats (6) and mice (7) after 104 weeks of dosing. Although, neither of these stu

Journal article

Kawai R, Ahmetaj-Shala B, Shih CC, Marei I, Bhatti K, Kirkby NS, Mitchell JAet al., 2018, Development of a human autologous 3-cell cytokine release assay that models the vascular wall in vitro, 54th Congress of the European-Societies-of-Toxicology (EUROTOX) - Toxicology Out of the Box, Publisher: ELSEVIER IRELAND LTD, Pages: S114-S114, ISSN: 0378-4274

Conference paper

Ahmetaj-Shala B, Olanipekun M, Tesfai A, MacCallum N, Kirkby N, Qunilan G, Shih C-C, Kawai R, Mumby S, Paul-Clark M, Want E, Mitchell JAet 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.

Journal article

Mitchell JA, Knowles RB, Kirkby NS, Reed DM, Edin ML, White WE, Chan MV, Longhurst H, Yaqoob MM, Milne GL, Zeldin DC, Warner TDet 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

Journal article

Kirkby NS, Sampaio W, Etelvino G, Alves DT, Anders KL, Temponi R, Shala F, Nair AS, Ahmetaj-Shala B, Jiao J, Herschman HR, Wang X, Wahli W, Santos RA, Mitchell JAet al., 2018, Cyclooxygenase-2 Selectively Controls Renal Blood Flow Through a Novel PPAR beta/delta-Dependent Vasodilator Pathway (vol 71, pg 297, 2018), HYPERTENSION, Vol: 71, Pages: e10-e10, ISSN: 0194-911X

Journal article

Mitchell J, Kirkby NS, 2018, Eicosanoids, prostacyclin and cyclooxygenase in the cardiovascular system, British Journal of Pharmacology, 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.

Journal article

Mitchell JA, Knowles RB, Kirkby NS, Reed DM, Edin ML, White WE, Chan MV, Longhurst H, Yaqoob MM, Milne GL, Zeldin DC, Warner TDet 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

Journal article

Kirkby NS, Sampaio W, Etelvino G, Alves D, Anders KL, Temponi R, Shala F, Nair AS, Ahmetaj-Shala B, Jiao J, Herschman HR, Xiaomeng W, Wahli W, Santos RA, Mitchell JAet 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.

Journal article

Kirkby NS, Morris AP, Lytton J, Seong JK, Bae YS, Chu JH, Bertagnolli MM, Pirmohamed M, Mitchell JAet 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

Conference paper

Mitchell JA, Shala F, Ahmetaj-Shala B, Jiao J, Armstrong PC, Chan MV, Crescente M, Warner TD, Herschman HR, Kirkby NSet 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

Conference paper

Mitchell JA, Benson J, Shala F, Ahmetaj-Shala B, Kirkby NSet 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

Conference paper

Kirkby NS, Jiao J, Herschman HR, Mitchell JAet 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

Conference paper

Tesfai A, MacCallum N, Kirkby NS, Gashaw H, Gray N, Quinlan G, Mumby S, Leiper JM, Paul-Clark M, Ahmetaj-Shala B, Mitchell JAet 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.

Journal article

Mohamed NA, Davies RP, Lickiss PD, Ahmetaj-Shala B, Reed DM, Gashaw HH, Saleem H, Freeman GR, George PM, Wort SJ, Morales-Cano D, Barreira B, Tetley TD, Chester AH, Yacoub MH, Kirkby NS, Moreno L, Mitchell JAet 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.

Journal article

Crescente M, Armstrong PC, Chan MV, Edin ML, Lih FB, Jiao J, Gaston-Massuet C, Cottrell GS, Kirkby NS, Mitchell JA, Zeldin DC, Herschman HR, Warner TDet 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

Conference paper

Parzych K, Zetterqvist A, Wright WR, Kirkby NS, Mitchell JA, Paul-Clark Met 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.

Journal article

Ahmetaj-Shala B, Tesfai A, Constantinou C, Leszczynski R, Chan MV, Gashaw HH, Galaris G, Mazi SI, Warner TD, Kirkby NS, Mitchell JAet 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.

Journal article

Duluc L, Ahmetaj-Shala B, Mitchell J, Abdul Salam VB, Mahomed AS, Aldabbous L, Oliver E, Iannone L, Dubois OD, Storck EM, Tate EW, Zhao L, Wilkins MR, Wojciak-Stothard Bet al., 2017, Tipifarnib prevents development of hypoxia-induced pulmonary hypertension, Cardiovascular Research, Vol: 113, Pages: 276-287, ISSN: 1755-3245

Aims.RhoB plays a key role in the pathogenesis of hypoxia-induced pulmonary hypertension. Farnesylated RhoB promotes growth responses in cancer cells and we investigated whether inhibition of protein farnesylation will have a protective effect. Methods and Results.The analysis of lung tissues from rodent models and pulmonary hypertensive patientsshowed increased levels of protein farnesylation. Oral farnesyltransferase inhibitor tipifarnib prevented development of hypoxia-induced pulmonary hypertension in mice. Tipifarnib reduced hypoxia-induced vascular cell proliferation, increased endothelium-dependent vasodilatation and reduced vasoconstriction of intrapulmonary arteries without affecting cell viability. Protective effects of tipifarnib were associated with inhibition of Ras and RhoB, actin depolymerisation and increased eNOS expression in vitroand in vivo. Farnesylated-only RhoB (F-RhoB) increased proliferative responses in cultured pulmonary vascular cells, mimicking the effects of hypoxia, while both geranylgeranylated-only RhoB (GG-RhoB) and tipifarnib had an inhibitory effect. Label-free proteomics linked F-RhoB with cell survival, activation of cell cycle and mitochondrial biogenesis. Hypoxia increased and tipifarnib reduced the levels of F-RhoB-regulated proteins in the lung, reinforcing the importance of RhoB as a signalling mediator.Unlike simvastatin, tipifarnib did not increase the expression levels of Rho proteins.Conclusions.Our study demonstrates the importance of protein farnesylation in pulmonary vascular remodeling and provides a rationale for selective targeting of this pathway in pulmonary hypertension.

Journal article

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