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Epigenetic Dysregulation of the Dynamin-Related Protein 1 Binding Partners MiD49 and MiD51 Increases Mitotic Mitochondrial Fission and Promotes Pulmonary Arterial Hypertension [Original Research Article]

Lun, 16/07/2018 - 19:44
Background:Mitotic fission is increased in pulmonary arterial hypertension (PAH), a hyperproliferative, apoptosis-resistant disease. The fission mediator dynamin-related protein 1 (Drp1) must complex with adaptor proteins to cause fission. Drp1-induced fission has been therapeutically targeted in experimental PAH. Here, we examine the role of 2 recently discovered, poorly understood Drp1 adapter proteins, mitochondrial dynamics protein of 49 and 51 kDa (MiD49 and MiD51), in normal vascular cells and explore their dysregulation in PAH.Methods:Immunoblots of pulmonary artery smooth muscle cells (control, n=6; PAH, n=8) and immunohistochemistry of lung sections (control, n=6; PAH, n=6) were used to assess the expression of MiD49 and MiD51. The effects of manipulating MiDs on cell proliferation, cell cycle, and apoptosis were assessed in human and rodent PAH pulmonary artery smooth muscle cells with flow cytometry. Mitochondrial fission was studied by confocal imaging. A microRNA (miR) involved in the regulation of MiD expression was identified using microarray techniques and in silico analyses. The expression of circulatory miR was assessed with quantitative reverse transcription–polymerase chain reaction in healthy volunteers (HVs) versus patients with PAH from Sheffield, UK (plasma: HV, n=29, PAH, n=27; whole blood: HV, n=11, PAH, n=14) and then confirmed in a cohort from Beijing, China (plasma: HV, n=19, PAH, n=36; whole blood: HV, n=20, PAH, n=39). This work was replicated in monocrotaline and Sugen 5416-hypoxia, preclinical PAH models. Small interfering RNAs targeting MiDs or an miR mimic were nebulized to rats with monocrotaline-induced PAH (n=4–10).Results:MiD expression is increased in PAH pulmonary artery smooth muscle cells, which accelerates Drp1-mediated mitotic fission, increases cell proliferation, and decreases apoptosis. Silencing MiDs (but not other Drp1 binding partners, fission 1 or mitochondrial fission factor) promotes mitochondrial fusion and causes G1-phase cell cycle arrest through extracellular signal-regulated kinases 1/2– and cyclin-dependent kinase 4–dependent mechanisms. Augmenting MiDs in normal cells causes fission and recapitulates the PAH phenotype. MiD upregulation results from decreased miR-34a-3p expression. Circulatory miR-34a-3p expression is decreased in both patients with PAH and preclinical models of PAH. Silencing MiDs or augmenting miR-34a-3p regresses experimental PAH.Conclusions:In health, MiDs regulate Drp1-mediated fission, whereas in disease, epigenetic upregulation of MiDs increases mitotic fission, which drives pathological proliferation and apoptosis resistance. The miR-34a-3p-MiD pathway offers new therapeutic targets for PAH.

Deciphering the Role of Lipid Droplets in Cardiovascular Disease [White Paper]

Lun, 16/07/2018 - 19:44
Lipid droplets (LDs) are distinct and dynamic organelles that affect the health of cells and organs. Much progress has been made in understanding how these structures are formed, how they interact with other cellular organelles, how they are used for storage of triacylglycerol in adipose tissue, and how they regulate lipolysis. Our understanding of the biology of LDs in the heart and vascular tissue is relatively primitive in comparison with LDs in adipose tissue and liver. The National Heart, Lung, and Blood Institute convened a working group to discuss how LDs affect cardiovascular diseases. The goal of the working group was to examine the current state of knowledge on the cell biology of LDs, including current methods to study them in cells and organs and reflect on how LDs influence the development and progression of cardiovascular diseases. This review summarizes the working group discussion and recommendations on research areas ripe for future investigation that will likely improve our understanding of atherosclerosis and heart function.

Time to Endovascular Treatment and Outcome in Acute Ischemic Stroke [Original Research Article]

Lun, 16/07/2018 - 19:44
Background:Randomized, clinical trials in selected acute ischemic stroke patients reported that for every hour delay of endovascular treatment (EVT), chances of functional independence diminish by up to 3.4%. These findings may not be fully generalizable to clinical practice because of strict in- and exclusion criteria in these trials. Therefore, we aim to assess the association of time to EVT with functional outcome in current, everyday clinical practice.Methods:The MR CLEAN Registry (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in The Netherlands) is an ongoing, prospective, observational study in all centers that perform EVT in The Netherlands. Data were analyzed from patients treated between March 2014 and June 2016. In the primary analysis we assessed the association of time from stroke onset to start of EVT and time from stroke onset to successful reperfusion with functional outcome (measured with the modified Rankin Scale), by means of ordinal logistic regression.Results:We analyzed 1488 patients with acute ischemic stroke who underwent EVT. An increased time to start of EVT was associated with worse functional outcome (adjusted common odds ratio, 0.83 per hour; 95% confidence interval, 0.77–0.89) and a 2.2% increase in mortality. Every hour increase from stroke onset to EVT start resulted in a 5.3% decreased probability of functional independence (modified Rankin Scale, 0–2). In the 742 patients with successful reperfusion, every hour increase from stroke onset to reperfusion was associated with a 7.7% decreased probability of functional independence.Conclusions:Time to EVT for acute ischemic stroke in current clinical practice is strongly associated with functional outcome. Our data suggest that this association might be even stronger than previously suggested in reports on more selected patient populations from randomized, controlled trials. These findings emphasize that functional outcome of EVT patients can be greatly improved by shortening onset to treatment times.

Impact of Novel Low-Density Lipoprotein-Cholesterol Assessment on the Utility of Secondary Non-High-Density Lipoprotein-C and Apolipoprotein B Targets in Selected Worldwide Dyslipidemia Guidelines [Original Research Article]

Lun, 16/07/2018 - 19:44
Background:Selected dyslipidemia guidelines recommend non-high-density lipoprotein-cholesterol (non-HDL-C) and apolipoprotein B (apoB) as secondary targets to the primary target of low-density lipoprotein-cholesterol (LDL-C). After considering 2 LDL-C estimates that differ in accuracy, we examined: (1) how frequently non-HDL-C guideline targets could change management; and (2) the utility of apoB targets after meeting LDL-C and non-HDL-C targets.Methods:We analyzed 2518 adults representative of the US population from the 2011 to 2012 National Health and Nutrition Examination Survey and 126?092 patients from the Very Large Database of Lipids study with apoB. We identified all individuals as well as those with high-risk clinical features, including coronary artery disease, diabetes mellitus, and metabolic syndrome who met very high- and high-risk guideline targets of LDL-C <70 and <100 mg/dL using Friedewald estimation (LDL-CF) and a novel, more accurate method (LDL-CN). Next, we examined those not meeting non-HDL-C (<100, <130 mg/dL) and apoB (<80, <100 mg/dL) guideline targets. In those meeting dual LDL-C and non-HDL-C targets (<70 and <100 mg/dL, respectively, or <100 and <130 mg/dL, respectively), we determined the proportion of individuals who did not meet guideline apoB targets (<80 or <100 mg/dL).Results:A total of 7% to 9% and 31% to 36% of individuals had LDL-C <70 and <100 mg/dL, respectively. Among those with LDL-CF<70 mg/dL, 14% to 15% had non-HDL-C ?100 mg/dL, and 7% to 8% had apoB ?80 mg/dL. Among those with LDL-CF<100 mg/dL, 8% to 10% had non-HDL-C ?130 mg/dL and 2% to 3% had apoB ?100 mg/dL. In comparison, among those with LDL-CN<70 or 100 mg/dL, only ?2% and ?1% of individuals, respectively, had non-HDL-C and apoB values above guideline targets. Similar trends were upheld among those with high-risk clinical features: ?0% to 3% of individuals with LDL-CN<70 mg/dL had non-HDL-C ?100 mg/dL or apoB ?80 mg/dL compared with 13% to 38% and 9% to 25%, respectively, in those with LDL-CF<70 mg/dL. With LDL-CF or LDL-CN<70 mg/dL and non-HDL-C <100 mg/dL, 0% to 1% had apoB ?80 mg/dL. Among all dual LDL-CF or LDL-CN<100 mg/dL and non-HDL-C <130 mg/dL individuals, 0% to 0.4% had apoB ?100 mg/dL. These findings were robust to sex, fasting status, and lipid-lowering therapy status.Conclusions:After more accurately estimating LDL-C, guideline-suggested non-HDL-C targets could alter management in only a small fraction of individuals, including those with coronary artery disease and other high-risk clinical features. Furthermore, current guideline-suggested apoB targets provide modest utility after meeting cholesterol targets.Clinical Trial Registration:URL: https://www.clinicaltrials.gov. Unique identifier: NCT01698489.

Association of Human Immunodeficiency Virus Infection and Risk of Peripheral Artery Disease [Original Research Article]

Lun, 16/07/2018 - 19:44
Background:The effect of human immunodeficiency virus (HIV) on the development of peripheral artery disease (PAD) remains unclear. We investigated whether HIV infection is associated with an increased risk of PAD after adjustment for traditional atherosclerotic risk factors in a large cohort of HIV-infected (HIV+) and demographically similar HIV-uninfected veterans.Methods:We studied participants in the Veterans Aging Cohort Study from April 1, 2003 through December 31, 2014. We excluded participants with known prior PAD or prevalent cardiovascular disease (myocardial infarction, stroke, coronary heart disease, and congestive heart failure) and analyzed the effect of HIV status on the risk of incident PAD events after adjusting for demographics, PAD risk factors, substance use, CD4 cell count, HIV-1 ribonucleic acid, and antiretroviral therapy. The primary outcome is incident peripheral artery disease events. Secondary outcomes include mortality and amputation in subjects with incident PAD events by HIV infection status, viral load, and CD4 count.Results:Among 91 953 participants, over a median follow up of 9.0 years, there were 7708 incident PAD events. Rates of incident PAD events per 1000 person-years were higher among HIV+ (11.9; 95% confidence interval [CI], 11.5–12.4) than uninfected veterans (9.9; 95% CI, 9.6–10.1). After adjustment for demographics, PAD risk factors, and other covariates, HIV+ veterans had an increased risk of incident PAD events compared with uninfected veterans (hazard ratio [HR], 1.19; 95% CI, 1.13–1.25). This risk was highest among those with time-updated HIV viral load >500 copies/mL (HR, 1.51; 95% CI, 1.38–1.65) and CD4 cell counts <200 cells/mm3 (HR, 1.91; 95% CI, 1.71–2.13). In contrast, HIV+ veterans with time updated CD4 cell count ?500 cells/mm3 had no increased risk of PAD (HR, 1.03; 95% CI, 0.96–1.11). Mortality rates after incident PAD events are high regardless of HIV status. HIV infection did not affect rates of amputation after incident PAD events.Conclusions:Infection with HIV is associated with a 19% increased risk of PAD beyond that explained by traditional atherosclerotic risk factors. However, for those with sustained CD4 cell counts <200 cells/mm3, the risk of incident PAD events is nearly 2-fold higher whereas for those with sustained CD4 cell counts ?500 cells/mm3 there is no excess risk of incident PAD events compared with uninfected people.

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