GEP analysis validates high risk MDS and acute myeloid leukemia post MDS mice models and highlights novel dysregulated pathways

International audienceBACKGROUND:In spite of the recent discovery of genetic mutations in most myelodysplasic (MDS) patients, the pathophysiology of these disorders still remains poorly understood, and only few in vivo models are available to help unravel the disease.METHODS:We performed global specific gene expression profiling and functional pathway analysis in purified Sca1+ cells of two MDS transgenic mouse models that mimic human high-risk MDS (HR-MDS) and acute myeloid leukemia (AML) post MDS, with NRASD12 and BCL2 transgenes under the control of different promoters MRP8NRASD12/tethBCL-2 or MRP8[NRASD12/hBCL-2], respectively.RESULTS:Analysis of dysregulated genes that were unique to the diseased HR-MDS and AML post MDS mice and not their founder mice pointed first to pathways that had previously been reported in MDS patients, including DNA replication/damage/repair, cell cycle, apoptosis, immune responses, and canonical Wnt pathways, further validating these models at the gene expression level. Interestingly, pathways not previously reported in MDS were discovered. These included dysregulated genes of noncanonical Wnt pathways and energy and lipid metabolisms. These dysregulated genes were not only confirmed in a different independent set of BM and spleen Sca1+ cells from the MDS mice but also in MDS CD34+ BM patient samples.CONCLUSIONS:These two MDS models may thus provide useful preclinical models to target pathways previously identified in MDS patients and to unravel novel pathways highlighted by this study

Monitoring the biological activity of abdominal aortic aneurysms Beyond Ultrasound

Abdominal aortic aneurysms (AAAs) are an important cause of morbidity and, when ruptured, are associated with >80% mortality. Current management decisions are based on assessment of aneurysm diameter by abdominal ultrasound. However, AAA growth is non-linear and rupture can occur at small diameters or may never occur in those with large AAAs. There is a need to develop better imaging biomarkers that can identify the potential risk of rupture independent of the aneurysm diameter. Key pathobiological processes of AAA progression and rupture include neovascularisation, necrotic inflammation, microcalcification and proteolytic degradation of the extracellular matrix. These processes represent key targets for emerging imaging techniques and may confer an increased risk of expansion or rupture over and above the known patient-related risk factors. Magnetic resonance imaging, using ultrasmall superparamagnetic particles of iron oxide, can identify and track hotspots of macrophage activity. Positron emission tomography, using a variety of targeted tracers, can detect areas of inflammation, angiogenesis, hypoxia and microcalcification. By going beyond the simple monitoring of diameter expansion using ultrasound, these cellular and molecular imaging techniques may have the potential to allow improved prediction of expansion or rupture and to better guide elective surgical intervention

Non-Invasive Molecular Imaging of Fibrosis Using a Collagen-Targeted Peptidomimetic of the Platelet Collagen Receptor Glycoprotein VI

Background: Fibrosis, which is characterized by the pathological accumulation of collagen, is recognized as an important feature of many chronic diseases, and as such, constitutes an enormous health burden. We need non-invasive specific methods for the early diagnosis and follow-up of fibrosis in various disorders. Collagen targeting molecules are therefore of interest for potential in vivo imaging of fibrosis. In this study, we developed a collagen-specific probe using a new approach that takes advantage of the inherent specificity of Glycoprotein VI (GPVI), the main platelet receptor for collagens I and III. Methodology/Principal: Findings An anti-GPVI antibody that neutralizes collagen-binding was used to screen a bacterial random peptide library. A cyclic motif was identified, and the corresponding peptide (designated collagelin) was synthesized. Solid-phase binding assays and histochemical analysis showed that collagelin specifically bound to collagen (Kd 10−7 M) in vitro, and labelled collagen fibers ex vivo on sections of rat aorta and rat tail. Collagelin is therefore a new specific probe for collagen. The suitability of collagelin as an in vivo probe was tested in a rat model of healed myocardial infarctions (MI). Injecting Tc-99m-labelled collagelin and scintigraphic imaging showed that uptake of the probe occurred in the cardiac area of rats with MI, but not in controls. Post mortem autoradiography and histological analysis of heart sections showed that the labeled areas coincided with fibrosis. Scintigraphic molecular imaging with collagelin provides high resolution, and good contrast between the fibrotic scars and healthy tissues. The capacity of collagelin to image fibrosis in vivo was confirmed in a mouse model of lung fibrosis. Conclusion/Significance: Collagelin is a new collagen-targeting agent which may be useful for non-invasive detection of fibrosis in a broad spectrum of diseases.Psycholog

BCL-2 Inhibitor ABT-737 effectively targets leukemia-initiating cells with differential regulation of relevant genes leading to extended survival in a NRAS/BCL-2 mouse model of high risk-myelodysplastic syndrome

During transformation, myelodysplastic syndromes (MDS) are characterized by reducing apoptosis of bone marrow (BM) precursors. Mouse models of high risk (HR)-MDS and acute myelogenous leukemia (AML) post-MDS using mutant NRAS and overexpression of human BCL-2, known to be poor prognostic indicators of the human diseases, were created. We have reported the efficacy of the BCL-2 inhibitor, ABT-737, on the AML post-MDS model; here, we report that this BCL-2 inhibitor also significantly extended survival of the HR-MDS mouse model, with reductions of BM blasts and lineage negative/Sca1+/KIT+ (LSK) cells. Secondary transplants showed increased survival in treated compared to untreated mice. Unlike the AML model, BCL-2 expression and RAS activity decreased following treatment and the RAS:BCL-2 complex remained in the plasma membrane. Exon-specific gene expression profiling (GEP) of HR-MDS mice showed 1952 differentially regulated genes upon treatment, including genes important for the regulation of stem cells, differentiation, proliferation, oxidative phosphorylation, mitochondrial function, and apoptosis; relevant in human disease. Spliceosome genes, found to be abnormal in MDS patients and downregulated in our HR-MDS model, such as Rsrc1 and Wbp4, were upregulated by the treatment, as were genes involved in epigenetic regulation, such as DNMT3A and B, upregulated upon disease progression and downregulated upon treatment

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Évaluation de radiotraceurs dérivés de l'annexine A5 pour l'imagerie scintigraphique de processus cellulaires (apoptose/nécrose/thrombose) en pathologie cardiovasculaire

L'annexine A5, protéine endogène de 35kDa, présente une forte affinité pour la phosphatidysérine (PS) exprimée par la surface des cellules apoptotiques et des plaquettes activées. L'annexine A5 radiomarquée au Tc-99m (99mTc-ANX5) a été développée par Strauss (Stanford, USA) comme traceur d'apoptose : apoptose tumorale induite par chimio-radiothérapie, lésions d'ischémie/reperfusion chez l'animal et chez l'homme, rejet de greffons. Par ailleurs, de nombreuses données in vitro suggèrent que l'annexine A5 marque également la nécrose (rupture de la membrane plasmique), qui survient à un stade plus ou moins tardif de tout processus de mort cellulaire. Ce travail s'inscrit dans un objectif global d'évaluer les possibilités de développement de l'imagerie scintigraphie à l'annexine A5 radiomarquée comme outil clinique en pathologie cardiovasculaire. Quatre études réalisées dans les modèles (rat) d'infarctus du myocarde par ligature coronaire ou ischémie-reperfusion, de myocardites subaiguë et toxique aiguë à l'isuprel, montrent que l'99mTc-ANX5 présente une grande sensibilité de détection in vivo de la mort myocutaire par apoptose ou nécrose, massive aiguë confluente (infarctus), ou progressive et non confluente (myocardites). Une autre étude rapporte les performances de l'99mTc-ANX5 pour l'imagerie in vivo de l'activité biologique du thrombus dans un modèle d'anévrysme de l'aorte abdominale (rat). Les résultats de ces travaux permettents d'envisager l'utilisation clinique de l'imagerie à l'ANX5 dans les myocardites aiguës et surtout diverses pathologies vasculaires à composante thrombotique.Annexin A5, a 35KDa protein, specifically binds with high affinity to phosphatidylsérine (PS) which is activally redistributed to the external leaflet of plasmic membrane in apoptotic cells and activated platelets. Annexin A5 radiolabelled with Tc-99m (99mTc-ANX5) was developped by Strauss (Stanford, USA) to image apoptosis in vivo : tumour cells apoptosis induced by chemo-radiotherapy, ischemia/reperfusion lesions in animals and patients, graft rejection. Additionally, many in vitro data suggest that annexin A5 also stains necrosis (membrane disruption), which occurs in all types of cell death. This preclinical work aimed to evaluate the potential interest of 99mTc-ANX5 imaging as a clinical tool in cardiovascular diseases.Four studies performed in rat models of myocardial infarction by coronary ligation ans ischemia-reperfusion, and in rat models of subacute and acute (isoproterenol-induced) myocarditis show the ability of 99mTc-ANX5 to detect in vivo cardiomyocytes death by apoptosis and necrosis. Another study demonstrates that 99mTc-ANX5 is highly accurate to evaluate in vivo the biological activity of parietal thrombus in a rat model of elastase-induced abdominal aortic aneurysm. These results suggest that 99mTc-ANX5 imaging could be used in patients for non invasive diagnosis, pronostic evaluation in acute myocarditis and in various thrombotic cardiovascular diseases.PARIS12-Bib. électronique (940280011) / SudocSudocFranceF