Fluorescence microscopy tensor imaging representations for large-scale dataset analysis

Understanding complex biological systems requires the system-wide characterization of cellular and molecular features. Recent advances in optical imaging technologies and chemical tissue clearing have facilitated the acquisition of whole-organ imaging datasets, but automated tools for their quantitative analysis and visualization are still lacking. We have here developed a visualization technique capable of providing whole-organ tensor imaging representations of local regional descriptors based on fluorescence data acquisition. This method enables rapid, multiscale, analysis and virtualization of large-volume, high-resolution complex biological data while generating 3D tractographic representations. Using the murine heart as a model, our method allowed us to analyze and interrogate the cardiac microvasculature and the tissue resident macrophage distribution and better infer and delineate the underlying structural network in unprecedented detail

Decrease of miR-146b-5p in Monocytes during Obesity Is Associated with Loss of the Anti-Inflammatory but Not Insulin Signaling Action of Adiponectin

Background: Low adiponectin, a well-recognized antidiabetic adipokine, has been associated with obesity-related inflammation, oxidative stress and insulin resistance. Globular adiponectin is an important regulator of the interleukin-1 receptor-associated kinase (IRAK)/NFkB pathway in monocytes of obese subjects. It protects against inflammation and oxidative stress by inducing IRAK3. microRNA (miR)-146b-5p inhibits NFkB-mediated inflammation by targeted repression of IRAK1 and TNF receptor-associated factor-6 (TRAF6). Therefore, we measured the expression of miR-146b-5p in monocytes of obese subjects. Because it was low we determined the involvement of this miR in the anti-inflammatory, antioxidative and insulin signaling action of globular adiponectin. Methods: miR-146b-5p expression in monocytes of obese subjects was determined by qRT-PCR. The effect of miR-146b-5p silencing on molecular markers of inflammation, oxidative stress and insulin signaling and the association with globular adiponectin was assessed in human THP-1 monocytes. Results: miR-146b-5p was downregulated in monocytes of obese persons. Low globular adiponectin decreased miR-146b-5p and IRAK3 in THP-1 monocytes, associated with increased mitochondrial reactive oxygen species (ROS). Intracellular ROS and insulin receptor substrate-1 (IRS1) protein were unchanged. Silencing of miR-146b-5p with an antisense inhibitor resulted in increased expression of IRAK1 and TRAF6 leading to more NFkB p65 DNA binding activity and TNFa. As

Targeting Interleukin-1β Reduces Leukocyte Production After Acute Myocardial Infarction

Background—Myocardial infarction (MI) is an ischemic wound that recruits millions of leukocytes. MI-associated blood leukocytosis correlates inversely with patient survival, yet the signals driving heightened leukocyte production after MI remain incompletely understood. Methods and Results—With the use of parabiosis surgery, this study shows that soluble danger signals, among them interleukin-1β, increase bone marrow hematopoietic stem cell proliferation after MI. Data obtained in bone marrow reconstitution experiments reveal that interleukin-1β enhances hematopoietic stem cell proliferation by both direct actions on hematopoietic cells and through modulation of the bone marrow’s hematopoietic microenvironment. An antibody that neutralizes interleukin-1β suppresses these effects. Anti-interleukin-1β treatment dampens the post-MI increase in hematopoietic stem cell proliferation. Consequently, decreased leukocyte numbers in the blood and infarct reduce inflammation and diminish post-MI heart failure in ApoE–/– mice with atherosclerosis. Conclusions—The presented insight into post-MI bone marrow activation identifies a mechanistic target for muting inflammation in the ischemically damaged heart

Acute mental stress drives vascular inflammation and promotes plaque destabilization in mouse atherosclerosis

Publisher Copyright: © 2021 The Author(s). Published by Oxford University Press on behalf of the European Society of Cardiology.Aims: Mental stress substantially contributes to the initiation and progression of human disease, including cardiovascular conditions. We aim to investigate the underlying mechanisms of these contributions since they remain largely unclear. Methods and results: Here, we show in humans and mice that leucocytes deplete rapidly from the blood after a single episode of acute mental stress. Using cell-tracking experiments in animal models of acute mental stress, we found that stress exposure leads to prompt uptake of inflammatory leucocytes from the blood to distinct tissues including heart, lung, skin, and, if present, atherosclerotic plaques. Mechanistically, we found that acute stress enhances leucocyte influx into mouse atherosclerotic plaques by modulating endothelial cells. Specifically, acute stress increases adhesion molecule expression and chemokine release through locally derived norepinephrine. Either chemical or surgical disruption of norepinephrine signalling diminished stress-induced leucocyte migration into mouse atherosclerotic plaques. Conclusion: Our data show that acute mental stress rapidly amplifies inflammatory leucocyte expansion inside mouse atherosclerotic lesions and promotes plaque vulnerability.publishersversionPeer reviewe

Interleukin-1 Receptor-Associated Kinase-3 Is a Key Inhibitor of Inflammation in Obesity and Metabolic Syndrome

BACKGROUND: Visceral obesity is associated with the rising incidence of type 2 diabetes and metabolic syndrome. Low-grade chronic inflammation and oxidative stress synergize in obesity and obesity-induced disorders. OBJECTIVE: We searched a cluster of molecules that support interactions between these stress conditions in monocytes. METHODS: RNA expressions in blood monocytes of two independent cohorts comprising 21 and 102 obese persons and 46 age-matched controls were determined by microarray and independently validated by quantitative RT-PCR analysis. The effect of three-month weight loss after bariatric surgery was determined. The effect of RNA silencing on inflammation and oxidative stress was studied in human monocytic THP-1 cells. RESULTS: Interleukin-1 receptor-associated kinase-3 (IRAK3), key inhibitor of IRAK/NFκB-mediated chronic inflammation, is downregulated in monocytes of obese persons. Low IRAK3 was associated with high superoxide dismutase-2 (SOD2), a marker of mitochondrial oxidative stress. A comparable expression profile was also detected in visceral adipose tissue of the same obese subjects. Low IRAK3 and high SOD2 was associated with a high prevalence of metabolic syndrome (odds ratio: 9.3; sensitivity: 91%; specificity: 77%). By comparison, the odds ratio of high-sensitivity C-reactive protein, a widely used marker of systemic inflammation, was 4.3 (sensitivity: 69%; specificity: 66%). Weight loss was associated with an increase in IRAK3 and a decrease in SOD2, in association with a lowering of systemic inflammation and a decreasing number of metabolic syndrome components. We identified the increase in reactive oxygen species in combination with obesity-associated low adiponectin and high glucose and interleukin-6 as cause of the decrease in IRAK3 in THP-1 cells in vitro. CONCLUSION: IRAK3 is a key inhibitor of inflammation in association with obesity and metabolic syndrome. Our data warrant further evaluation of IRAK3 as a diagnostic and prognostic marker, and as a target for intervention

Neutrophils incite and macrophages avert electrical storm after myocardial infarction

Sudden cardiac death, arising from abnormal electrical conduction, occurs frequently in patients with coronary heart disease. Myocardial ischemia simultaneously induces arrhythmia and massive myocardial leukocyte changes. In this study, we optimized a mouse model in which hypokalemia combined with myocardial infarction triggered spontaneous ventricular tachycardia in ambulatory mice, and we showed that major leukocyte subsets have opposing effects on cardiac conduction. Neutrophils increased ventricular tachycardia via lipocalin-2 in mice, whereas neutrophilia associated with ventricular tachycardia in patients. In contrast, macrophages protected against arrhythmia. Depleting recruited macrophages in Ccr2−/− mice or all macrophage subsets with Csf1 receptor inhibition increased both ventricular tachycardia and fibrillation. Higher arrhythmia burden and mortality in Cd36−/− and Mertk−/− mice, viewed together with reduced mitochondrial integrity and accelerated cardiomyocyte death in the absence of macrophages, indicated that receptor-mediated phagocytosis protects against lethal electrical storm. Thus, modulation of leukocyte function provides a potential therapeutic pathway for reducing the risk of sudden cardiac death

Inflammation and oxidative stress in circulating monocytes in relation to obesity and associated metabolic disorders

Cardiovascular diseases (CVD) are still the main cause of mortality and morbidity worldwide. This can be explained by the increasing prevalence of obesity and type 2 diabetes. The risk of developing CVD is directly related to the concomitant burden of obesity-related risk factors clustered in the metabolic syndrome: dyslipidemia, hyperglycemia and insulin resistance, and hypertension. Indeed, increased inflammation and oxidative stress associated with obesity play a central role in the development of obesity-induced metabolic disorders such as metabolic syndrome, type 2 diabetes and atherosclerosis. However, the underlying cellular and molecular mechanisms that link these processes remain to be elucidated. Therefore, the aim of this dissertation is to unravel the mechanisms of inflammation and oxidative stress during obesity and associated metabolic disorders.First, we discuss cellular and molecular mechanisms explaining the existence of a vicious circle between inflammation and oxidative stress in obese adipose and atherosclerotic vascular tissues. Inflammatory cells like monocytes and macrophages play a significant role in initiating the inflammatory cascade leading to enhanced oxidative stress. The enhanced oxidative stress, at its turn, increases the infiltration of inflammatory cells emphasizing the existence of a vicious circle. Moreover, circulating monocytes are already activated in obese individuals and are characterized by an increased inflammatory and oxidative stress state. Since these peripheral blood cells are easily accessible, gene expression analysis in circulating monocytes could yield valuable biomarkers that may reflect presence and activity of obesity-associated metabolic disorders.Second, we identify a cluster of genes that connects chronic inflammation with oxidative stress in circulating monocytes of obese individuals before infiltrating adipose or vascular tissues. IRAK3 is the only downregulated inhibitor of this gene cluster in obese monocytes. Low IRAK3 is associated with high SOD2, a marker of mitochondrial oxidative stress. Interestingly, the combination of low IRAK3 and high SOD2 is the strongest predictor of metabolic syndrome; it is even stronger than C-reactive protein. In addition, we identify the increase in oxidative stress in combination with obesity-associated low adiponectin as cause of the decrease in IRAK3.Third, we discuss the involvement of regulating microRNAs (miRs) in the increased inflammatory and oxidative stress state associated with obesity and related metabolic disorders. Hereby, we review miRs that share similar expression profiles in the diseased tissues during obesity and atherosclerosis. These common miRs regulate molecules related to processes that play a role in the development of obesity-associated diseases, and may be especially useful targets for treatment.Fourth, we identify several differentially expressed miRs in circulating monocytes of obese individuals that are involved in the regulation of the IRAK3-related cluster and are associated with metabolic syndrome and CVD. For example, we identify miR-146b-5p as downregulated miR with validated targets in the IRAK3-related gene cluster and as major mediator of the anti-inflammatory action of adiponectin on monocytes. miR-181a is also downregulated in monocytes of obese patients and an in silico analysis identifies several molecules in the IRAK3-related gene cluster as putative targets. Interestingly, miR-181a predicts a higher number of metabolic syndrome components and is associated with the occurrence of coronary artery disease even after adjustment for traditional risk factors, obesity and the metabolic syndrome.To conclude we identify a gene/miR signature in monocytes of obese patients with interesting perspectives for risk stratification for the prevention and treatment of obesity-associated metabolic disorders. Early detection of obese individuals at highest risk of developing co-morbidities makes it possible to present these patients with the best treatment option to attenuate their risk and associated mortality rate.nrpages: 186status: publishe

Low Cytochrome Oxidase 1 Links Mitochondrial Dysfunction to Atherosclerosis in Mice and Pigs

<div><p>Background</p><p>Cytochrome oxidase IV complex regulates energy production in mitochondria. Therefore, we determined the relation of COX genes with atherosclerosis in mice and pigs.</p><p>Methods and results</p><p>First, we compared atherosclerosis in the aortic arch of age-matched (24 weeks) C57BL/6J control (n = 10), LDL-receptor deficient (n = 8), leptin-deficient ob/ob (n = 10), and double knock-out (lacking LDL-receptor and leptin) mice (n = 12). Low aortic <i>mitochondria-encoded cytochrome oxidase 1</i> in obese diabetic double knock-out mice was associated with a larger plaque area and higher propensity of M1 macrophages and oxidized LDL. Caloric restriction increased <i>mitochondria-encoded cytochrome oxidase 1</i> and reduced plaque area and oxidized LDL. This was associated with a reduction of titer of anti-oxidized LDL antibodies, a proxy of systemic oxidative stress. Low of <i>mitochondria-encoded cytochrome oxidase 1</i> was related to low expression of peroxisome proliferative activated receptors α, δ, and γ and of peroxisome proliferative activated receptor, gamma, co-activator 1 alpha reflecting mitochondrial dysfunction. Caloric restriction increased them. To investigate if there was a diabetic/obesity requirement for <i>mitochondria-encoded cytochrome oxidase 1</i> to be down-regulated, we then studied atherosclerosis in LAD of hypercholesterolemic pigs (n = 37). Pigs at the end of the study were divided in three groups based on increasing LAD plaque complexity according to Stary (Stary I: n = 12; Stary II: n = 13; Stary III: n = 12). Low <i>mitochondria-encoded cytochrome oxidase 1</i> in isolated plaque macrophages was associated with more complex coronary plaques and oxidized LDL. Nucleus-encoded cytochrome oxidase <i>4I1</i> and cytochrome oxidase <i>10</i> did not correlate with plaque complexity and oxidative stress. In mice and pigs, <i>MT-COI</i> was inversely related to insulin resistance.</p><p>Conclusions</p><p>Low <i>MT-COI</i> is related to mitochondrial dysfunction, oxidative stress and atherosclerosis and plaque complexity.</p></div