Publications by authors named "Ajay M Shah"

301 Publications

Role of oxidative stress in calcific aortic valve disease and its therapeutic implications.

Cardiovasc Res 2021 Apr 21. Epub 2021 Apr 21.

King's College London British Heart Foundation Centre of Research Excellence, London, UK.

Calcific aortic valve disease (CAVD) is the end result of active cellular processes that lead to the progressive fibrosis and calcification of aortic valve leaflets. In western populations, CAVD is a significant cause of cardiovascular morbidity and mortality, and in the absence of effective drugs, it will likely represent an increasing disease burden as populations age. As there are currently no pharmacological therapies available for preventing, treating, or slowing the development of CAVD, understanding the mechanisms underlying the initiation and progression of the disease is important for identifying novel therapeutic targets. Recent evidence has emerged of an important causative role for reactive oxygen species (ROS)-mediated oxidative stress in the pathophysiology of CAVD, inducing the differentiation of valve interstitial cells into myofibroblasts and then osteoblasts. In this review we focus on the roles and sources of ROS driving CAVD and consider their potential as novel therapeutic targets for this debilitating condition.
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http://dx.doi.org/10.1093/cvr/cvab142DOI Listing
April 2021

Rotigaptide Infusion for the First 7 Days After Myocardial Infarction-Reperfusion Reduced Late Complexity of Myocardial Architecture of the Healing Border-Zone and Arrhythmia Inducibility.

J Am Heart Assoc 2021 Apr 17:e020006. Epub 2021 Apr 17.

National Heart & Lung Institute and ElectroCardioMaths Programme of the Imperial Centre for Cardiac EngineeringImperial College London London United Kingdom.

Background Survivors of myocardial infarction are at increased risk of late ventricular arrhythmias, with infarct size and scar heterogeneity being key determinants of arrhythmic risk. Gap junctions facilitate the passage of small ions and morphogenic cell signaling between myocytes. We hypothesized that gap junctions enhancement during infarction-reperfusion modulates structural and electrophysiological remodeling and reduces late arrhythmogenesis. Methods and Results Infarction-reperfusion surgery was carried out in male Sprague-Dawley rats followed by 7 days of rotigaptide or saline administration. The in vivo and ex vivo arrhythmogenicity was characterized by programmed electrical stimulation 3 weeks later, followed by diffusion-weighted magnetic resonance imaging and Masson's trichrome histology. Three weeks after 7-day postinfarction administration of rotigaptide, ventricular tachycardia/ventricular fibrillation was induced on programmed electrical stimulation in 20% and 53% of rats, respectively (rotigaptide versus control), resulting in reduction of arrhythmia score (3.2 versus 1.4, =0.018), associated with the reduced magnetic resonance imaging parameters fractional anisotropy (fractional anisotropy: -5% versus -15%; =0.062) and mean diffusivity (mean diffusivity: 2% versus 6%, =0.042), and remodeling of the 3-dimensional laminar structure of the infarct border zone with reduction of the mean (16° versus 19°, =0.013) and the dispersion (9° versus 12°, =0.015) of the myofiber transverse angle. There was no change in ECG features, spontaneous arrhythmias, or mortality. Conclusions Enhancement of gap junctions function by rotigaptide administered during the early healing phase in reperfused infarction reduces later complexity of infarct scar morphology and programmed electrical stimulation-induced arrhythmias, and merits further exploration as a feasible and practicable intervention in the acute myocardial infarction management to reduce late arrhythmic risk.
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http://dx.doi.org/10.1161/JAHA.120.020006DOI Listing
April 2021

Development and validation of a cellular host response test as an early diagnostic for sepsis.

PLoS One 2021 15;16(4):e0246980. Epub 2021 Apr 15.

Louisiana State University Health Sciences Center, Baton Rouge, Louisiana, United States of America.

Sepsis must be diagnosed quickly to avoid morbidity and mortality. However, the clinical manifestations of sepsis are highly variable and emergency department (ED) clinicians often must make rapid, impactful decisions before laboratory results are known. We previously developed a technique that allows the measurement of the biophysical properties of white blood cells as they are stretched through a microfluidic channel. In this study we describe and validate the resultant output as a model and score-the IntelliSep Index (ISI)-that aids in the diagnosis of sepsis in patients with suspected or confirmed infection from a single blood draw performed at the time of ED presentation. By applying this technique to a high acuity cohort with a 23.5% sepsis incidence (n = 307), we defined specific metrics-the aspect ratio and visco-elastic inertial response-that are more sensitive than cell size or cell count in predicting disease severity. The final model was trained and cross-validated on the high acuity cohort, and the performance and generalizability of the model was evaluated on a separate low acuity cohort with a 6.4% sepsis incidence (n = 94) and healthy donors (n = 72). For easier clinical interpretation, the ISI is divided into three interpretation bands of Green, Yellow, and Red that correspond to increasing disease severity. The ISI agreed with the diagnosis established by retrospective physician adjudication, and accurately identified subjects with severe illness as measured by SOFA, APACHE-II, hospital-free days, and intensive care unit admission. Measured using routinely collected blood samples, with a short run-time and no requirement for patient or laboratory information, the ISI is well suited to aid ED clinicians in rapidly diagnosing sepsis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246980PLOS
April 2021

Genetic deletion of Nox4 enhances cancerogen-induced formation of solid tumors.

Proc Natl Acad Sci U S A 2021 Mar;118(11)

Institute for Cardiovascular Physiology, Goethe University, 60590 Frankfurt am Main, Germany;

Reactive oxygen species (ROS) can cause cellular damage and promote cancer development. Besides such harmful consequences of overproduction of ROS, all cells utilize ROS for signaling purposes and stabilization of cell homeostasis. In particular, the latter is supported by the NADPH oxidase 4 (Nox4) that constitutively produces low amounts of HO By that mechanism, Nox4 forces differentiation of cells and prevents inflammation. We hypothesize a constitutive low level of HO maintains basal activity of cellular surveillance systems and is unlikely to be cancerogenic. Utilizing two different murine models of cancerogen-induced solid tumors, we found that deletion of Nox4 promotes tumor formation and lowers recognition of DNA damage. Nox4 supports phosphorylation of H2AX (γH2AX), a prerequisite of DNA damage recognition, by retaining a sufficiently low abundance of the phosphatase PP2A in the nucleus. The underlying mechanism is continuous oxidation of AKT by Nox4. Interaction of oxidized AKT and PP2A captures the phosphatase in the cytosol. Absence of Nox4 facilitates nuclear PP2A translocation and dephosphorylation of γH2AX. Simultaneously AKT is left phosphorylated. Thus, in the absence of Nox4, DNA damage is not recognized and the increased activity of AKT supports proliferation. The combination of both events results in genomic instability and promotes tumor formation. By identifying Nox4 as a protective source of ROS in cancerogen-induced cancer, we provide a piece of knowledge for understanding the role of moderate production of ROS in preventing the initiation of malignancies.
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http://dx.doi.org/10.1073/pnas.2020152118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7980388PMC
March 2021

Drugs that inhibit TMEM16 proteins block SARS-CoV-2 Spike-induced syncytia.

Nature 2021 Apr 7. Epub 2021 Apr 7.

King's College London, British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine & Sciences, London, UK.

COVID-19 is a disease with unique characteristics including lung thrombosis, frequent diarrhoea, abnormal activation of the inflammatory response and rapid deterioration of lung function consistent with alveolar oedema. The pathological substrate for these findings remains elusive. Here we show that the lungs of patients with COVID-19 contain infected pneumocytes with abnormal morphology and frequent multinucleation. Generation of these syncytia results from activation of the SARS-CoV-2 Spike protein at the cell plasma membrane level. Based on these observations, we performed two high-content microscopy-based screenings with over 3000 approved drugs to search for inhibitors of Spike-driven syncytia. We converged on the identification of 83 drugs that inhibited Spike-mediated cell fusion, several of which belonged to defined pharmacological classes. We focussed our attention on effective drugs that also protected against virus replication and associated cytopathicity. One of the most effective molecules was Niclosamide, which markedly blunted calcium oscillations and membrane conductances in Spike-expressing cells by suppressing the activity of TMEM16F/Anoctamin6, a calcium-activated ion channel and scramblase responsible for phosphatidylserine exposure on the cell surface. These findings suggest a potential mechanism for COVID-19 disease pathogenesis and support the repurposing of Niclosamide for therapy.
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http://dx.doi.org/10.1038/s41586-021-03491-6DOI Listing
April 2021

X-box binding protein 1-mediated COL4A1s secretion regulates communication between vascular smooth muscle and stem/progenitor cells.

J Biol Chem 2021 Mar 12:100541. Epub 2021 Mar 12.

School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, Faculty of Life Science and Medicine, King's College London. London SE5 9NU, UK. Electronic address:

Vascular smooth muscle cells (VSMCs) contribute to the deposition of extracellular matrix proteins (ECMs), including Type IV collagen, in the vessel wall. ECMs coordinate communication among different cell types, but mechanisms underlying this communication remain unclear. Our previous studies have demonstrated that X-box binding protein 1 (XBP1) is activated and contributes to VSMC phenotypic transition in response to vascular injury. In this study, we investigated the participation of XBP1 in the communication between VSMCs and vascular progenitor cells (VPCs). Immunofluorescence and immunohistology staining revealed that Xbp1 gene was essential for COL4A1 expression during mouse embryonic development and vessel wall ECM deposition and stem cell antigen 1-positive (Sca1)-VPC recruitment in response to vascular injury. Western blot analysis elucidated an Xbp1 gene dose-dependent effect on COL4A1 expression and that the spliced XBP1 protein (XBP1s) increased protease-mediated COL4A1 degradation as revealed by Zymography. RT-PCR analysis revealed that XBP1s in VSMCs not only upregulated COL4A1/2 transcription but also induced the occurrence of a novel transcript variant, COL4A1s, in which the front part of exon 4 is joined with the rear part of exon 42. Chromatin-immunoprecipitation, DNA/protein pulldown and in vitro transcription demonstrated that XBP1s binds to exon 4 and exon 42, directing the transcription from exon 4 to exon 42. This leads to transcription complex bypassing the internal sequences, producing a shortened soluble COL4A1s protein that increased Sca1-VPC migration. Taken together, these results suggest that activated VSMCs may recruit Sca1-VPCs via XBP1s-mediated COL4A1s secretion, leading to vascular injury repair or neointima formation.
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http://dx.doi.org/10.1016/j.jbc.2021.100541DOI Listing
March 2021

Excess deaths in people with cardiovascular diseases during the COVID-19 pandemic.

Eur J Prev Cardiol 2021 Feb 21. Epub 2021 Feb 21.

Institute of Health Informatics, University College London, 222 Euston Road, London, UK, NW1 1DA.

Aims: Cardiovascular diseases (CVDs) increase mortality risk from coronavirus infection (COVID-19). There are also concerns that the pandemic has affected supply and demand of acute cardiovascular care. We estimated excess mortality in specific CVDs, both 'direct', through infection, and 'indirect', through changes in healthcare.

Methods And Results: We used (i) national mortality data for England and Wales to investigate trends in non-COVID-19 and CVD excess deaths; (ii) routine data from hospitals in England (n = 2), Italy (n = 1), and China (n = 5) to assess indirect pandemic effects on referral, diagnosis, and treatment services for CVD; and (iii) population-based electronic health records from 3 862 012 individuals in England to investigate pre- and post-COVID-19 mortality for people with incident and prevalent CVD. We incorporated pre-COVID-19 risk (by age, sex, and comorbidities), estimated population COVID-19 prevalence, and estimated relative risk (RR) of mortality in those with CVD and COVID-19 compared with CVD and non-infected (RR: 1.2, 1.5, 2.0, and 3.0).Mortality data suggest indirect effects on CVD will be delayed rather than contemporaneous (peak RR 1.14). CVD service activity decreased by 60-100% compared with pre-pandemic levels in eight hospitals across China, Italy, and England. In China, activity remained below pre-COVID-19 levels for 2-3 months even after easing lockdown and is still reduced in Italy and England. For total CVD (incident and prevalent), at 10% COVID-19 prevalence, we estimated direct impact of 31 205 and 62 410 excess deaths in England (RR 1.5 and 2.0, respectively), and indirect effect of 49 932 to 99 865 deaths.

Conclusion: Supply and demand for CVD services have dramatically reduced across countries with potential for substantial, but avoidable, excess mortality during and after the pandemic.
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http://dx.doi.org/10.1093/eurjpc/zwaa155DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7928969PMC
February 2021

Biological responses to COVID-19: Insights from physiological and blood biomarker profiles.

Curr Res Transl Med 2021 Feb 3;69(2):103276. Epub 2021 Feb 3.

Department of Biostatistics and Health Informatics, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; NIHR Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, London, UK. Electronic address:

Background: Understanding the spectrum and course of biological responses to coronavirus disease 2019 (COVID-19) may have important therapeutic implications. We sought to characterise biological responses among patients hospitalised with severe COVID-19 based on serial, routinely collected, physiological and blood biomarker values.

Methods And Findings: We performed a retrospective cohort study of 1335 patients hospitalised with laboratory-confirmed COVID-19 (median age 70 years, 56 % male), between 1st March and 30th April 2020. Latent profile analysis was performed on serial physiological and blood biomarkers. Patient characteristics, comorbidities and rates of death and admission to intensive care, were compared between the latent classes. A five class solution provided the best fit. Class 1 "Typical response" exhibited a moderately elevated and rising C-reactive protein (CRP), stable lymphopaenia, and the lowest rates of 14-day adverse outcomes. Class 2 "Rapid hyperinflammatory response" comprised older patients, with higher admission white cell and neutrophil counts, which declined over time, accompanied by a very high and rising CRP and platelet count, and exibited the highest mortality risk. Class 3 "Progressive inflammatory response" was similar to the typical response except for a higher and rising CRP, though similar mortality rate. Class 4 "Inflammatory response with kidney injury" had prominent lymphopaenia, moderately elevated (and rising) CRP, and severe renal failure. Class 5 "Hyperinflammatory response with kidney injury" comprised older patients, with a very high and rising CRP, and severe renal failure that attenuated over time. Physiological measures did not substantially vary between classes at baseline or early admission.

Conclusions And Relevance: Our identification of five distinct classes of biomarker profiles provides empirical evidence for heterogeneous biological responses to COVID-19. Early hyperinflammatory responses and kidney injury may signify unique pathophysiology that requires targeted therapy.
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http://dx.doi.org/10.1016/j.retram.2021.103276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857048PMC
February 2021

Iron derived from autophagy-mediated ferritin degradation induces cardiomyocyte death and heart failure in mice.

Elife 2021 Feb 2;10. Epub 2021 Feb 2.

The School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London, United Kingdom.

Heart failure is a major public health problem, and abnormal iron metabolism is common in patients with heart failure. Although iron is necessary for metabolic homeostasis, it induces a programmed necrosis. Iron release from ferritin storage is through nuclear receptor coactivator 4 (NCOA4)-mediated autophagic degradation, known as ferritinophagy. However, the role of ferritinophagy in the stressed heart remains unclear. Deletion of in mouse hearts reduced left ventricular chamber size and improved cardiac function along with the attenuation of the upregulation of ferritinophagy-mediated ferritin degradation 4 weeks after pressure overload. Free ferrous iron overload and increased lipid peroxidation were suppressed in NCOA4-deficient hearts. A potent inhibitor of lipid peroxidation, ferrostatin-1, significantly mitigated the development of pressure overload-induced dilated cardiomyopathy in wild-type mice. Thus, the activation of ferritinophagy results in the development of heart failure, whereas inhibition of this process protects the heart against hemodynamic stress.
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http://dx.doi.org/10.7554/eLife.62174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7853718PMC
February 2021

Endothelial NADPH oxidase 4 protects against angiotensin II-induced cardiac fibrosis and inflammation.

ESC Heart Fail 2021 Apr 29;8(2):1427-1437. Epub 2021 Jan 29.

School of Cardiovascular Medicine and Sciences, James Black Centre, King's College London British Heart Foundation Centre of Excellence, 125 Coldharbour Lane, London, SE5 9NU, UK.

Aims: Endothelial activation and inflammatory cell infiltration have important roles in the development of cardiac fibrosis induced by renin-angiotensin system activation. NADPH oxidases (Nox proteins) are expressed in endothelial cells (ECs) and alter their function. Previous studies indicated that Nox2 in ECs contributes to angiotensin II (AngII)-induced cardiac fibrosis. However, the effects of EC Nox4 on cardiac fibrosis are unknown.

Methods And Results: Transgenic (TG) mice overexpressing endothelial-restricted Nox4 were studied alongside wild-type (WT) littermates as controls. At baseline, Nox4 TG mice had significantly enlarged hearts compared with WT, with elongated cardiomyocytes (increased by 18.5%, P < 0.01) and eccentric hypertrophy but well-preserved cardiac function by echocardiography and in vivo pressure-volume analysis. Animals were subjected to a chronic AngII infusion (AngII, 1.1 mg/kg/day) for 14 days. Whereas WT/AngII developed a 2.1-fold increase in interstitial cardiac fibrosis as compared with WT/saline controls (P < 0.01), TG/AngII mice developed significant less fibrosis (1.4-fold increase, P > 0.05), but there were no differences in cardiac hypertrophy or contractile function between the two groups. TG hearts displayed significantly decreased inflammatory cell infiltration with reduced levels of vascular cell adhesion molecule 1 in both the vasculature and myocardium compared with WT after AngII treatment. TG microvascular ECs stimulated with AngII in vitro supported significantly less leukocyte adhesion than WT ECs.

Conclusions: A chronic increase in endothelial Nox4 stimulates physiological cardiac hypertrophy and protects against AngII-induced cardiac fibrosis by inhibiting EC activation and the recruitment of inflammatory cells.
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http://dx.doi.org/10.1002/ehf2.13228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8006688PMC
April 2021

Colchicine and the Heart: Old Friends, Old Foes.

Rheumatology (Oxford) 2021 Jan 25. Epub 2021 Jan 25.

Centre for Rheumatic Diseases, King's College London, London, UK.

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http://dx.doi.org/10.1093/rheumatology/keab062DOI Listing
January 2021

An update on the roles of immune system derived microRNAs in cardiovascular diseases.

Cardiovasc Res 2021 Jan 23. Epub 2021 Jan 23.

School of Immunology and Microbial Sciences, King's College London, Great Maze Pond, London, SE1 9RT, United Kingdom.

Cardiovascular diseases (CVD) are a leading cause of human death worldwide. Over the past two decades, the emerging field of cardioimmunology has demonstrated how cells of the immune system play vital roles in the pathogenesis of CVD. MicroRNAs (miRNAs) are critical regulators of cellular identity and function. Cell-intrinsic, as well as cell-extrinsic, roles of immune and inflammatory cell derived miRNAs have been, and continue to be, extensively studied. Several ''immuno-miRNAs'' appear to be specifically expressed or demonstrate greatly enriched expression within leucocytes. Identification of miRNAs as critical regulators of immune system signalling pathways has posed the question of whether and how targeting these molecules therapeutically, may afford opportunities for disease treatment and/or management. As the field of cardioimmunology rapidly continues to advance, this review discusses findings from recent human and murine studies which contribute to our understanding of how leucocytes of innate and adaptive immunity are regulated-and may also regulate other cell types, via the actions of the microRNAs they express, in the context of CVD. Finally, we focus on available information regarding microRNA regulation of regulatory T cells (TREGS) and argue that targeted manipulation of microRNA regulated pathways in these cells may hold therapeutic promise for the treatment of CVD and associated risk factors.
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http://dx.doi.org/10.1093/cvr/cvab007DOI Listing
January 2021

Inducibility, but not stability, of atrial fibrillation is increased by NOX2 overexpression in mice.

Cardiovasc Res 2021 Jan 23. Epub 2021 Jan 23.

Division of Cardiovascular Medicine, University of Oxford, UK.

Aims: Gp91-containing NADPH oxidases (NOX2) are a significant source of myocardial superoxide production. An increase in NOX2 activity accompanies atrial fibrillation (AF) induction and electrical remodelling in animal models and predicts incident AF in humans; however, a direct causal role for NOX2 in AF has not been demonstrated. Accordingly, we investigated whether myocardial NOX2 overexpression in mice (NOX2-Tg) is sufficient to generate a favourable substrate for AF and further assessed the effects of atorvastatin, an inhibitor of NOX2, on atrial superoxide production and AF susceptibility.

Methods And Results: NOX2-Tg mice showed a 2-2.5-fold higher atrial protein content of NOX2 compared with wild-type (WT) controls, which was associated with a significant (2-fold) increase in NADPH-stimulated superoxide production (2-hydroxyethidium by HPLC) in left and right atrial tissue homogenates (P = 0.004 and P = 0.019, respectively). AF susceptibility assessed in vivo by transoesophageal atrial burst stimulation was modestly increased in NOX2-Tg compared with WT (probability of AF induction: 88% vs. 69%, respectively; P = 0.037), in the absence of significant alterations in AF duration, surface ECG parameters, and LV mass or function. Mechanistic studies did not support a role for NOX2 in promoting electrical or structural remodelling, as high-resolution optical mapping of atrial tissues showed no differences in action potential duration and conduction velocity between genotypes. In addition, we did not observe any genotype difference in markers of fibrosis and inflammation, including atrial collagen content and Col1a1, Il-1β, Il-6, and Mcp-1 mRNA. Similarly, NOX2 overexpression did not have consistent effects on RyR2 Ca2+ leak nor did it affect PKA or CaMKII-mediated RyR2 phosphorylation. Finally, treatment with atorvastatin significantly inhibited atrial superoxide production in NOX2-Tg but had no effect on AF induction in either genotype.

Conclusions: Together, these data indicate that whilst atrial NOX2 overexpression may contribute to atrial arrhythmogenesis, NOX2-derived superoxide production does not affect the electrical and structural properties of the atrial myocardium.

Translational Perspective: Atrial NOX2-derived superoxide is an independent predictor of postoperative AF in humans and contributes to atrial oxidative stress early after AF induction. Whilst experimental models have reported an association of NOX2 with AF-induced remodelling, a causal link between NOX2 activity and AF remains to be established. Here we show that overexpression of the human NOX2 gene in mice resulted in a 2-fold higher atrial superoxide production and a modest increase in AF susceptibility, independent of atrial electrical or structural remodelling. Short-term treatment with atorvastatin normalized atrial superoxide in NOX2-Tg mice without affecting AF susceptibility. Together these findings indicate that atrial NOX2-derived superoxide is more likely a biomarker of AF risk than a primary driver of AF development, and that NOX2 inhibition is unlikely to prevent the new-onset of AF.
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http://dx.doi.org/10.1093/cvr/cvab019DOI Listing
January 2021

Evaluation and improvement of the National Early Warning Score (NEWS2) for COVID-19: a multi-hospital study.

BMC Med 2021 01 21;19(1):23. Epub 2021 Jan 21.

Department of Biostatistics and Health Informatics, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, 16 De Crespigny Park, London, SE5 8AF, UK.

Background: The National Early Warning Score (NEWS2) is currently recommended in the UK for the risk stratification of COVID-19 patients, but little is known about its ability to detect severe cases. We aimed to evaluate NEWS2 for the prediction of severe COVID-19 outcome and identify and validate a set of blood and physiological parameters routinely collected at hospital admission to improve upon the use of NEWS2 alone for medium-term risk stratification.

Methods: Training cohorts comprised 1276 patients admitted to King's College Hospital National Health Service (NHS) Foundation Trust with COVID-19 disease from 1 March to 30 April 2020. External validation cohorts included 6237 patients from five UK NHS Trusts (Guy's and St Thomas' Hospitals, University Hospitals Southampton, University Hospitals Bristol and Weston NHS Foundation Trust, University College London Hospitals, University Hospitals Birmingham), one hospital in Norway (Oslo University Hospital), and two hospitals in Wuhan, China (Wuhan Sixth Hospital and Taikang Tongji Hospital). The outcome was severe COVID-19 disease (transfer to intensive care unit (ICU) or death) at 14 days after hospital admission. Age, physiological measures, blood biomarkers, sex, ethnicity, and comorbidities (hypertension, diabetes, cardiovascular, respiratory and kidney diseases) measured at hospital admission were considered in the models.

Results: A baseline model of 'NEWS2 + age' had poor-to-moderate discrimination for severe COVID-19 infection at 14 days (area under receiver operating characteristic curve (AUC) in training cohort = 0.700, 95% confidence interval (CI) 0.680, 0.722; Brier score = 0.192, 95% CI 0.186, 0.197). A supplemented model adding eight routinely collected blood and physiological parameters (supplemental oxygen flow rate, urea, age, oxygen saturation, C-reactive protein, estimated glomerular filtration rate, neutrophil count, neutrophil/lymphocyte ratio) improved discrimination (AUC = 0.735; 95% CI 0.715, 0.757), and these improvements were replicated across seven UK and non-UK sites. However, there was evidence of miscalibration with the model tending to underestimate risks in most sites.

Conclusions: NEWS2 score had poor-to-moderate discrimination for medium-term COVID-19 outcome which raises questions about its use as a screening tool at hospital admission. Risk stratification was improved by including readily available blood and physiological parameters measured at hospital admission, but there was evidence of miscalibration in external sites. This highlights the need for a better understanding of the use of early warning scores for COVID.
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http://dx.doi.org/10.1186/s12916-020-01893-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817348PMC
January 2021

Targeted deletion of NADPH-Oxidase Nox4 from proximal tubules is dispensable for diabetic kidney disease development.

Nephrol Dial Transplant 2020 Dec 24. Epub 2020 Dec 24.

Baker Heart & Diabetes Institute, Melbourne, Victoria, Australia.

Background: The NADPH oxidase isoform, Nox4, mediates reactive oxygen species (ROS) production and renal fibrosis in diabetic kidney disease at the level of the podocyte. However, the mitochondrial localization of Nox4 and its role as a mitochondrial bioenergetic sensor has recently been reported. Whether Nox4 drives pathology in diabetic kidney disease within the proximal tubular compartment, which is densely packed with mitochondria, is not yet known.

Methods: We generated a proximal tubular specific Nox4 knockout mouse model by breeding Nox4flox/flox mice with mice expressing Cre recombinase under the control of the Sglt2 promoter. Subsets of Nox4ptKO mice and their Nox4flox/flox littermates were injected with streptozotocin (STZ) to induce diabetes. Mice were followed for 20 weeks and renal injury was assessed.

Results: Genetic ablation of proximal tubular Nox4 (Nox4ptKO) resulted in no change in renal function and histology. Nox4ptKO mice and Nox4flox/flox littermates injected with STZ exhibited the hallmarks of diabetic kidney disease including hyperfiltration, albuminuria, renal fibrosis and glomerulosclerosis. Surprisingly, diabetes-induced renal injury was not improved in Nox4ptKOSTZ mice compared to Nox4flox/flox STZ mice. Although diabetes conferred ROS overproduction and increased mitochondrial oxygen consumption rate, proximal tubular deletion of Nox4 did not normalize oxidative stress or mitochondrial bioenergetics.

Conclusion: Taken together, these results demonstrate that genetic deletion of Nox4 from the proximal tubules does not influence diabetic kidney disease development, indicating that Nox4 localization within this highly energetic compartment is dispensable for chronic kidney disease pathogenesis in the setting of diabetes.
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http://dx.doi.org/10.1093/ndt/gfaa376DOI Listing
December 2020

Enriched conditioning expands the regenerative ability of sensory neurons after spinal cord injury via neuronal intrinsic redox signaling.

Nat Commun 2020 12 21;11(1):6425. Epub 2020 Dec 21.

Division of Neuroscience, Department of Brain Sciences, Imperial College London, London, UK.

Overcoming the restricted axonal regenerative ability that limits functional repair following a central nervous system injury remains a challenge. Here we report a regenerative paradigm that we call enriched conditioning, which combines environmental enrichment (EE) followed by a conditioning sciatic nerve axotomy that precedes a spinal cord injury (SCI). Enriched conditioning significantly increases the regenerative ability of dorsal root ganglia (DRG) sensory neurons compared to EE or a conditioning injury alone, propelling axon growth well beyond the spinal injury site. Mechanistically, we established that enriched conditioning relies on the unique neuronal intrinsic signaling axis PKC-STAT3-NADPH oxidase 2 (NOX2), enhancing redox signaling as shown by redox proteomics in DRG. Finally, NOX2 conditional deletion or overexpression respectively blocked or phenocopied enriched conditioning-dependent axon regeneration after SCI leading to improved functional recovery. These studies provide a paradigm that drives the regenerative ability of sensory neurons offering a potential redox-dependent regenerative model for mechanistic and therapeutic discoveries.
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http://dx.doi.org/10.1038/s41467-020-20179-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7752916PMC
December 2020

Systemic inflammation and oxidative stress contribute to acute kidney injury after transcatheter aortic valve implantation.

Cardiol J 2020 Dec 21. Epub 2020 Dec 21.

Department of Cardiology, Kings College Hospital and King's College London, Denmark Hill, SE5 9RS London, United Kingdom.

Background: Acute kidney injury (AKI) is a frequent complication of transcatheter aortic valve implantation (TAVI) and has been linked to preexisting comorbidities, peri-procedural hypotension, and systemic inflammation. The extent of systemic inflammation after TAVI is not fully understood. Our aim was to characterize the inflammatory response after TAVI and evaluate its contribution to the mechanism of post-procedural AKI.

Methods: One hundred and five consecutive patients undergoing TAVI at our institution were included. We analyzed the peri-procedural inflammatory and oxidative stress responses by measuring a range of biomarkers (including C-reactive protein [hsCRP], cytokine levels, and myeloperoxidase [MPO]), before TAVI and 6, 24, and 48 hours post-procedure. We correlated this with changes in renal function and patient and procedural characteristics.

Results: We observed a significant increase in plasma levels of pro-inflammatory cytokines (hsCRP, interleukin 6, tumor necrosis factor alpha receptors) and markers of oxidative stress (MPO) after TAVI. The inflammatory response was significantly greater after trans-apical (TA) TAVI compared to trans-femoral (TF). This was associated with a higher incidence of AKI in the TA cohort compared to TF (44% vs. 8%, respectively, p < 0.0001). The incidence of AKI was significantly lower when N-acetylcysteine (NAC) was given peri-procedurally (12% vs. 38%, p < 0.005). In multivariate analysis, only the TA approach and no use of NAC before the procedure were independent predictors of AKI.

Conclusions: TAVI creates a significant post-procedural inflammatory response, more so with the TA approach. Mechanisms of AKI after TAVI are complex. Inflammatory response, hypoperfusion, and oxidative stress may all play a part and are potential therapeutic targets to reduce/prevent AKI.
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http://dx.doi.org/10.5603/CJ.a2020.0169DOI Listing
December 2020

A Proteomics-Based Assessment of Inflammation Signatures in Endotoxemia.

Mol Cell Proteomics 2021 Feb 24;20:100021. Epub 2021 Feb 24.

King's College London British Heart Foundation Centre, School of Cardiovascular Medicine and Sciences, London, United Kingdom. Electronic address:

We have previously shown that multimers of plasma pentraxin-3 (PTX3) were predictive of survival in patients with sepsis. To characterize the release kinetics and cellular source of plasma protein changes in sepsis, serial samples were obtained from healthy volunteers (n = 10; three time points) injected with low-dose endotoxin (lipopolysaccharide [LPS]) and analyzed using data-independent acquisition MS. The human plasma proteome response was compared with an LPS-induced endotoxemia model in mice. Proteomic analysis of human plasma revealed a rapid neutrophil degranulation signature, followed by a rise in acute phase proteins. Changes in circulating PTX3 correlated with increases in neutrophil-derived proteins following LPS injection. Time course analysis of the plasma proteome in mice showed a time-dependent increase in multimeric PTX3, alongside increases in neutrophil-derived myeloperoxidase (MPO) upon LPS treatment. The mechanisms of oxidation-induced multimerization of PTX3 were explored in two genetic mouse models: MPO global knock-out (KO) mice and LysM Cre Nox2 KO mice, in which NADPH oxidase 2 (Nox2) is only deficient in myeloid cells. Nox2 is the enzyme responsible for the oxidative burst in neutrophils. Increases in plasma multimeric PTX3 were not significantly different between wildtype and MPO or LysM Cre Nox2 KO mice. Thus, PTX3 may already be stored and released in a multimeric form. Through in vivo neutrophil depletion and multiplexed vascular proteomics, PTX3 multimer deposition within the aorta was confirmed to be neutrophil dependent. Proteomic analysis of aortas from LPS-injected mice returned PTX3 as the most upregulated protein, where multimeric PTX3 was deposited as early as 2 h post-LPS along with other neutrophil-derived proteins. In conclusion, the rise in multimeric PTX3 upon LPS injection correlates with neutrophil-related protein changes in plasma and aortas. MPO and myeloid Nox2 are not required for the multimerization of PTX3; instead, neutrophil extravasation is responsible for the LPS-induced deposition of multimeric PTX3 in the aorta.
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http://dx.doi.org/10.1074/mcp.RA120.002305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7950208PMC
February 2021

Fibroblast Nox2 (NADPH Oxidase-2) Regulates ANG II (Angiotensin II)-Induced Vascular Remodeling and Hypertension via Paracrine Signaling to Vascular Smooth Muscle Cells.

Arterioscler Thromb Vasc Biol 2020 Oct 15:ATVBAHA120315322. Epub 2020 Oct 15.

King's College London British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine and Sciences, United Kingdom (C.B.H., S.C.T., D.A.R., C.X.C.S., G.S., X.Z., M.Z., A.C.B., X.Y., M.M., A.M.S.).

Objective: The superoxide-generating Nox2 (NADPH oxidase-2) is expressed in multiple cell types. Previous studies demonstrated distinct roles for cardiomyocyte, endothelial cell, and leukocyte cell Nox2 in ANG II (angiotensin II)-induced cardiovascular remodeling. However, the in vivo role of fibroblast Nox2 remains unclear. Approach and Results: We developed a novel mouse model with inducible fibroblast-specific deficiency of Nox2 (Fibro-Nox2KO mice) and investigated the responses to chronic ANG II stimulation. Fibro-Nox2KO mice showed no differences in basal blood pressure or vessel wall morphology, but the hypertensive response to ANG II infusion (1.1 mg/[kg·day] for 14 days) was substantially reduced as compared to control Nox2-Flox littermates. This was accompanied by a significant attenuation of aortic and resistance vessel remodeling. The conditioned medium of ANG II-stimulated primary fibroblasts induced a significant increase in vascular smooth muscle cell, which was inhibited by the shRNA-mediated knockdown of fibroblast Nox2. Mass spectrometric analysis of the secretome of ANG II-treated primary fibroblasts identified GDF6 (growth differentiation factor 6) as a potential growth factor that may be involved in these effects. Recombinant GDF6 induced a concentration-dependent increase in vascular smooth muscle cell growth while chronic ANG II infusion in vivo significantly increased aortic GDF6 protein levels in control mice but not Fibro-Nox2KO animals. Finally, silencing GDF6 in fibroblasts prevented the induction of vascular smooth muscle cell growth by fibroblast-conditioned media in vitro.

Conclusions: These results indicate that fibroblast Nox2 plays a crucial role in the development of ANG II-induced vascular remodeling and hypertension in vivo. Mechanistically, fibroblast Nox2 may regulate paracrine signaling to medial vascular smooth muscle cells via factors, such as GDF6.
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http://dx.doi.org/10.1161/ATVBAHA.120.315322DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7837692PMC
October 2020

A case-control and cohort study to determine the relationship between ethnic background and severe COVID-19.

EClinicalMedicine 2020 Nov 9;28:100574. Epub 2020 Oct 9.

School of Cardiovascular Medicine and Sciences, James Black Centre, King's College London British Heart Foundation Centre, 125 Coldharbour Lane, London SE5 9NU, UK.

Background: People of minority ethnic backgrounds may be disproportionately affected by severe COVID-19. Whether this relates to increased infection risk, more severe disease progression, or worse in-hospital survival is unknown. The contribution of comorbidities or socioeconomic deprivation to ethnic patterning of outcomes is also unclear.

Methods: We conducted a case-control and a cohort study in an inner city primary and secondary care setting to examine whether ethnic background affects the risk of hospital admission with severe COVID-19 and/or in-hospital mortality. Inner city adult residents admitted to hospital with confirmed COVID-19 ( = 872 cases) were compared with 3,488 matched controls randomly sampled from a primary healthcare database comprising 344,083 people residing in the same region. For the cohort study, we studied 1827 adults consecutively admitted with COVID-19. The primary exposure variable was self-defined ethnicity. Analyses were adjusted for socio-demographic and clinical variables.

Findings: The 872 cases comprised 48.1% Black, 33.7% White, 12.6% Mixed/Other and 5.6% Asian patients. In conditional logistic regression analyses, Black and Mixed/Other ethnicity were associated with higher admission risk than white (OR 3.12 [95% CI 2.63-3.71] and 2.97 [2.30-3.85] respectively). Adjustment for comorbidities and deprivation modestly attenuated the association (OR 2.24 [1.83-2.74] for Black, 2.70 [2.03-3.59] for Mixed/Other). Asian ethnicity was not associated with higher admission risk (adjusted OR 1.01 [0.70-1.46]). In the cohort study of 1827 patients, 455 (28.9%) died over a median (IQR) of 8 (4-16) days. Age and male sex, but not Black (adjusted HR 1.06 [0.82-1.37]) or Mixed/Other ethnicity (adjusted HR 0.72 [0.47-1.10]), were associated with in-hospital mortality. Asian ethnicity was associated with higher in-hospital mortality but with a large confidence interval (adjusted HR 1.71 [1.15-2.56]).

Interpretation: Black and Mixed ethnicity are independently associated with greater admission risk with COVID-19 and may be risk factors for development of severe disease, but do not affect in-hospital mortality risk. Comorbidities and socioeconomic factors only partly account for this and additional ethnicity-related factors may play a large role. The impact of COVID-19 may be different in Asians.

Funding: British Heart Foundation; the National Institute for Health Research; Health Data Research UK.
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http://dx.doi.org/10.1016/j.eclinm.2020.100574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7545271PMC
November 2020

Tissue Doppler-Derived Left Ventricular Systolic Velocity Is Associated with Lethal Arrhythmias in Cardiac Device Recipients Irrespective of Left Ventricular Ejection Fraction.

J Am Soc Echocardiogr 2020 12 10;33(12):1509-1516. Epub 2020 Oct 10.

School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, James Black Centre, London, United Kingdom; Department of Cardiology, King's College Hospital, London, United Kingdom. Electronic address:

Background: Life-threatening arrhythmias (LTAs) can trigger sudden cardiac death or provoke implantable cardioverter-defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium, which is uniquely sensitive to arrhythmogenic triggers. In this study, we test the hypothesis that mitral annular systolic velocity (S'), a simple routinely obtained tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of left ventricular ejection fraction (LVEF).

Methods: This is a retrospective analysis of data from 302 patients (mean age, 68 years; LVEF, 32%; 77% male; 52% ischemic; 35% primary prevention; and 53% cardiac resynchronization therapy defibrillator [CRT-D]) who were followed up (median, 15 months) at two centers after receipt of an ICD or CRT-D for diverse indications. S', averaged from tissue Doppler-derived medial and lateral mitral annular velocities, was correlated with the primary outcome of time to sustained ventricular tachycardia (VT) or fibrillation (VF) needing device therapy.

Results: The median S' was 5.1 (interquartile range, 4.0-6.2) cm/sec and lower in CRT-D than ICD subjects (4.5 [3.8-5.6] cm/sec vs 5.5 [4.8-6.8] cm/sec, P < .001). Fifty-six (19%) subjects had LTA. Each 1 cm/sec higher S' correlated to a 30% decreased risk of LTA (hazard ratio = 0.70; 95% CI, 0.57-0.87; P = .001) independently of age, sex, β-blocker use, center, ICD use, and LVEF. Adding S' to the baseline Cox model improved net reclassification (P = .02). An S' > 5.6 cm/sec was the best cutoff and linked to a 58% lower LTA risk than an S' ≤ 5.6 cm/sec (95% CI, 0.23-0.85; P = .02).

Conclusions: A higher S' is associated with a reduced probability of LTA in cardiac device recipients irrespective of LVEF and may have the potential to be used clinically to titrate medical, device, and ablative therapies to mitigate future arrhythmic risk.
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http://dx.doi.org/10.1016/j.echo.2020.08.013DOI Listing
December 2020

Nox4 regulates InsP receptor-dependent Ca release into mitochondria to promote cell survival.

EMBO J 2020 10 10;39(19):e103530. Epub 2020 Aug 10.

School of Cardiovascular Medicine & Sciences, King's College London British Heart Foundation Centre, London, UK.

Cells subjected to environmental stresses undergo regulated cell death (RCD) when homeostatic programs fail to maintain viability. A major mechanism of RCD is the excessive calcium loading of mitochondria and consequent triggering of the mitochondrial permeability transition (mPT), which is especially important in post-mitotic cells such as cardiomyocytes and neurons. Here, we show that stress-induced upregulation of the ROS-generating protein Nox4 at the ER-mitochondria contact sites (MAMs) is a pro-survival mechanism that inhibits calcium transfer through InsP receptors (InsP R). Nox4 mediates redox signaling at the MAM of stressed cells to augment Akt-dependent phosphorylation of InsP R, thereby inhibiting calcium flux and mPT-dependent necrosis. In hearts subjected to ischemia-reperfusion, Nox4 limits infarct size through this mechanism. These results uncover a hitherto unrecognized stress pathway, whereby a ROS-generating protein mediates pro-survival effects through spatially confined signaling at the MAM to regulate ER to mitochondria calcium flux and triggering of the mPT.
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http://dx.doi.org/10.15252/embj.2019103530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7527947PMC
October 2020

Invasive versus non-invasive management of older patients with non-ST elevation myocardial infarction (SENIOR-NSTEMI): a cohort study based on routine clinical data.

Lancet 2020 08;396(10251):623-634

National Institute for Health Research Imperial Biomedical Research Centre, Imperial College London and Imperial College Healthcare NHS Trust, London, UK. Electronic address:

Background: Previous trials suggest lower long-term risk of mortality after invasive rather than non-invasive management of patients with non-ST elevation myocardial infarction (NSTEMI), but the trials excluded very elderly patients. We aimed to estimate the effect of invasive versus non-invasive management within 3 days of peak troponin concentration on the survival of patients aged 80 years or older with NSTEMI.

Methods: Routine clinical data for this study were obtained from five collaborating hospitals hosting NIHR Biomedical Research Centres in the UK (all tertiary centres with emergency departments). Eligible patients were 80 years old or older when they underwent troponin measurements and were diagnosed with NSTEMI between 2010 (2008 for University College Hospital) and 2017. Propensity scores (patients' estimated probability of receiving invasive management) based on pretreatment variables were derived using logistic regression; patients with high probabilities of non-invasive or invasive management were excluded. Patients who died within 3 days of peak troponin concentration without receiving invasive management were assigned to the invasive or non-invasive management groups based on their propensity scores, to mitigate immortal time bias. We estimated mortality hazard ratios comparing invasive with non-invasive management, and compared the rate of hospital admissions for heart failure.

Findings: Of the 1976 patients with NSTEMI, 101 died within 3 days of their peak troponin concentration and 375 were excluded because of extreme propensity scores. The remaining 1500 patients had a median age of 86 (IQR 82-89) years of whom (845 [56%] received non-invasive management. During median follow-up of 3·0 (IQR 1·2-4·8) years, 613 (41%) patients died. The adjusted cumulative 5-year mortality was 36% in the invasive management group and 55% in the non-invasive management group (adjusted hazard ratio 0·68, 95% CI 0·55-0·84). Invasive management was associated with lower incidence of hospital admissions for heart failure (adjusted rate ratio compared with non-invasive management 0·67, 95% CI 0·48-0·93).

Interpretation: The survival advantage of invasive compared with non-invasive management appears to extend to patients with NSTEMI who are aged 80 years or older.

Funding: NIHR Imperial Biomedical Research Centre, as part of the NIHR Health Informatics Collaborative.
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http://dx.doi.org/10.1016/S0140-6736(20)30930-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456783PMC
August 2020

Temporal trends in decompensated heart failure and outcomes during COVID-19: a multisite report from heart failure referral centres in London.

Eur J Heart Fail 2020 12 28;22(12):2219-2224. Epub 2020 Sep 28.

School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London, UK.

Aims: Admission rates for acute decompensated heart failure (HF) declined during the COVID-19 pandemic. However, the impact of this reduction on hospital mortality is unknown. We describe temporal trends in the presentation of patients with acute HF and their in-hospital outcomes at two referral centres in London during the COVID-19 pandemic.

Methods And Results: A total of 1372 patients hospitalized for HF in two referral centres in South London between 7 January and 14 June 2020 were included in the study and their outcomes compared with those of equivalent patients of the same time period in 2019. The primary outcome was all-cause in-hospital mortality. The number of HF hospitalizations was significantly reduced during the COVID-19 pandemic, compared with 2019 (P < 0.001). Specifically, we observed a temporary reduction in hospitalizations during the COVID-19 peak, followed by a return to 2019 levels. Patients admitted during the COVID-19 pandemic had demographic characteristics similar to those admitted during the equivalent period in 2019. However, in-hospital mortality was significantly higher in 2020 than in 2019 (P = 0.015). Hospitalization in 2020 was independently associated with worse in-hospital mortality (hazard ratio 2.23, 95% confidence interval 1.34-3.72; P = 0.002).

Conclusions: During the COVID-19 pandemic there was a reduction in HF hospitalization and a higher rate of in-hospital mortality. Hospitalization for HF in 2020 is independently associated with more adverse outcomes. Further studies are required to investigate the predictors of these adverse outcomes to help inform potential changes to the management of HF patients while some constraints to usual care remain.
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http://dx.doi.org/10.1002/ejhf.1986DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7461082PMC
December 2020

Nitric Oxide Synthase Inhibitors into the Clinic at Last.

Handb Exp Pharmacol 2021 ;264:169-204

Knowles Consulting Ltd., The Stevenage Bioscience Catalyst, Stevenage, UK.

The 1998 Nobel Prize in Medicine and Physiology for the discovery of nitric oxide, a nitrogen containing reactive oxygen species (also termed reactive nitrogen or reactive nitrogen/oxygen species) stirred great hopes. Clinical applications, however, have so far pertained exclusively to the downstream signaling of cGMP enhancing drugs such as phosphodiesterase inhibitors and soluble guanylate cyclase stimulators. All clinical attempts, so far, to inhibit NOS have failed even though preclinical models were strikingly positive and clinical biomarkers correlated perfectly. This rather casts doubt on our current way of target identification in drug discovery in general and our way of patient stratification based on correlating but not causal biomarkers or symptoms. The opposite, NO donors, nitrite and enhancing NO synthesis by eNOS/NOS3 recoupling in situations of NO deficiency, are rapidly declining in clinical relevance or hold promise but need yet to enter formal therapeutic guidelines, respectively. Nevertheless, NOS inhibition in situations of NO overproduction often jointly with enhanced superoxide (or hydrogen peroxide production) still holds promise, but most likely only in acute conditions such as neurotrauma (Stover et al., J Neurotrauma 31(19):1599-1606, 2014) and stroke (Kleinschnitz et al., J Cereb Blood Flow Metab 1508-1512, 2016; Casas et al., Proc Natl Acad Sci U S A 116(14):7129-7136, 2019). Conversely, in chronic conditions, long-term inhibition of NOS might be too risky because of off-target effects on eNOS/NOS3 in particular for patients with cardiovascular risks or metabolic and renal diseases. Nitric oxide synthases (NOS) and their role in health (green) and disease (red). Only neuronal/type 1 NOS (NOS1) has a high degree of clinical validation and is in late stage development for traumatic brain injury, followed by a phase II safety/efficacy trial in ischemic stroke. The pathophysiology of NOS1 (Kleinschnitz et al., J Cereb Blood Flow Metab 1508-1512, 2016) is likely to be related to parallel superoxide or hydrogen peroxide formation (Kleinschnitz et al., J Cereb Blood Flow Metab 1508-1512, 2016; Casas et al., Proc Natl Acad Sci U S A 114(46):12315-12320, 2017; Casas et al., Proc Natl Acad Sci U S A 116(14):7129-7136, 2019) leading to peroxynitrite and protein nitration, etc. Endothelial/type 3 NOS (NOS3) is considered protective only and its inhibition should be avoided. The preclinical evidence for a role of high-output inducible/type 2 NOS (NOS2) isoform in sepsis, asthma, rheumatic arthritis, etc. was high, but all clinical development trials in these indications were neutral despite target engagement being validated. This casts doubt on the role of NOS2 in humans in health and disease (hence the neutral, black coloring).
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http://dx.doi.org/10.1007/164_2020_382DOI Listing
February 2021

A practical risk score for early prediction of neurological outcome after out-of-hospital cardiac arrest: MIRACLE2.

Eur Heart J 2020 12;41(47):4508-4517

Department of Cardiology, King's College Hospital NHS Foundation Trust, Denmark Hill, London SE59RS, UK.

Aims: The purpose of this study was to develop a practical risk score to predict poor neurological outcome after out-of-hospital cardiac arrest (OOHCA) for use on arrival to a Heart Attack Centre.

Methods And Results: From May 2012 to December 2017, 1055 patients had OOHCA in our region, of whom 373 patients were included in the King's Out of Hospital Cardiac Arrest Registry (KOCAR). We performed prediction modelling with multivariable logistic regression to identify predictors of the primary outcome to derive a risk score. This was externally validated in two independent cohorts comprising 473 patients. The primary endpoint was poor neurological outcome at 6-month follow-up (Cerebral Performance Category 3-5). Seven independent predictors of outcome were identified: missed (unwitnessed) arrest, initial non-shockable rhythm, non-reactivity of pupils, age (60-80 years-1 point; >80 years-3 points), changing intra-arrest rhythms, low pH <7.20, and epinephrine administration (2 points). The MIRACLE2 score had an area under the curve (AUC) of 0.90 in the development and 0.84/0.91 in the validation cohorts. Three risk groups were defined-low risk (MIRACLE2 ≤2-5.6% risk of poor outcome); intermediate risk (MIRACLE2 of 3-4-55.4% of poor outcome); and high risk (MIRACLE2 ≥5-92.3% risk of poor outcome). The MIRACLE2 score had superior discrimination than the OHCA [median AUC 0.83 (0.818-0.840); P < 0.001] and Cardiac Arrest Hospital Prognosis models [median AUC 0.87 (0.860-0.870; P = 0.001] and equivalent performance with the Target Temperature Management score [median AUC 0.88 (0.876-0.887); P = 0.092].

Conclusions: The MIRACLE2 is a practical risk score for early accurate prediction of poor neurological outcome after OOHCA, which has been developed for simplicity of use on admission.
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http://dx.doi.org/10.1093/eurheartj/ehaa570DOI Listing
December 2020

Predictive model of increased mortality and bed occupancy if thrombolysis becomes the initial treatment strategy for STEMI during the SARS-CoV-2 pandemic.

Clin Med (Lond) 2020 09 27;20(5):e170-e172. Epub 2020 Jul 27.

The King's College London British Heart Foundation Centre of Research Excellence, London, UK.

During the current SARS-CoV-2 pandemic the restructure of healthcare services to meet the huge increase in demand for hospital resource and capacity has led to the proposal that where necessary ST elevation myocardial infarction (STEMI) could be managed by intravenous thrombolysis in the first instance as a means of reducing the workforce requirements of a primary angioplasty service run at a heart attack centre. Our modelling, based on data from the UK, shows that contrary to reducing demand, the effect on both mortality and bed occupancy would be negative with 158 additional deaths per year for each 10% reduction in primary angioplasty and at a cost of ~8,000 additional bed days per year for the same reduction. Our analysis demonstrates that specialist services such as heart attack pathways should be protected during the COVID crisis to maximise the appropriate use of resource and prevent unnecessary mortality.
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http://dx.doi.org/10.7861/clinmed.2020-0293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7539733PMC
September 2020

In vivo [U-C]glucose labeling to assess heart metabolism in murine models of pressure and volume overload.

Am J Physiol Heart Circ Physiol 2020 08 10;319(2):H422-H431. Epub 2020 Jul 10.

King's College London British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine & Sciences, London, United Kingdom.

Alterations in the metabolism of substrates such as glucose are integrally linked to the structural and functional changes that occur in the remodeling heart. Assessment of such metabolic changes under in vivo conditions would provide important insights into this interrelationship. We aimed to investigate glucose carbon metabolism in pressure-overload and volume-overload cardiac hypertrophy by using an in vivo [U-C]glucose labeling strategy to enable analyses of the metabolic fates of glucose carbons in the mouse heart. Therefore, [U-C]glucose was administered in anesthetized mice by tail vein infusion, and the optimal duration of infusion was established. Hearts were then excised for C metabolite isotopomer analysis by NMR spectroscopy. [U-C]glucose infusions were performed in mice 2 wk following transverse aortic constriction (TAC) or aortocaval fistula (Shunt) surgery. At this time point, there were similar increases in left ventricular (LV) mass in both groups, but TAC resulted in concentric hypertrophy with impaired LV function, whereas Shunt caused eccentric hypertrophy with preserved LV function. TAC was accompanied by significant changes in glycolysis, mitochondrial oxidative metabolism, glucose metabolism to anaplerotic substrates, and de novo glutamine synthesis. In contrast to TAC, hardly any metabolic changes could be observed in the Shunt group. Taken together, in vivo [U-C]glucose labeling is a valuable method to investigate the fate of nutrients such as glucose in the remodeling heart. We find that concentric and eccentric cardiac remodeling are accompanied by distinct differences in glucose carbon metabolism. This study implemented a method for assessing the fate of glucose carbons in the heart in vivo and used this to demonstrate that pressure and volume overload are associated with distinct changes. In contrast to volume overload, pressure overload-induced changes affect the tricarboxylic acid cycle, glycolytic pathways, and glutamine synthesis. A better understanding of cardiac glucose metabolism under pathological conditions in vivo may provide new therapeutic strategies specific for different types of hemodynamic overload.
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http://dx.doi.org/10.1152/ajpheart.00219.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7473922PMC
August 2020