Description: Glucagon-like peptide-1 receptor agonists, used to treat type 2 diabetes mellitus, are associated with small reductions in systolic blood pressure (SBP) and increases in heart rate. However, findings based on clinic measurements do not adequately assess a drug’s 24-hour pharmacodynamic profile. The effects of dulaglutide, a once-weekly glucagon-like peptide-1 receptor agonist, on BP and heart rate were investigated using ambulatory BP monitoring. Patients (n=755; 56±10 years; 81% white; 48% women), with type 2 diabetes mellitus, taking ≥1 oral antihyperglycemic medication, with a clinic BP between 90/60 and 140/90 mm Hg were randomized to dulaglutide (1.5 or 0.75 mg) or placebo subcutaneously for 26 weeks. Ambulatory BP monitoring was performed at baseline and at 4, 16, and 26 weeks. The primary end point was change from baseline to week 16 in mean 24-hour SBP, a tree gatekeeping strategy compared the effects of dulaglutide to placebo. Both doses of dulaglutide were noninferior to placebo for changes in 24-hour SBP and diastolic blood pressure, and dulaglutide 1.5 mg significantly reduced SBP (least squares mean difference [95% confidence interval]), –2.8 mm Hg [–4.6, –1.0]; P ≤0.001). Dulaglutide 0.75 mg was noninferior to placebo (1.6 bpm; [0.3, 2.9]; P ≤0.02) for 24-hour heart rate (least squares mean difference [95% confidence interval]), but dulaglutide 1.5 mg was not (2.8 bpm [1.5, 4.2]). Dulaglutide 1.5 mg was associated with a reduction in 24-hour SBP and an increase in 24-hour heart rate. The mechanisms responsible for the observed effects remain to be clarified.

Description: Objective— Tyrosine kinase receptor B (TrkB) is a high-affinity receptor for brain-derived neurotrophic factor. In addition to its nervous system functions, TrkB is also expressed in the cardiovascular system. However, the association of TrkB and coronary artery disease (CAD) remains unknown. We investigated the role of TrkB in the development of CAD and its mechanism. Approach and Results— We performed a case–control study in 2 independent cohort of Chinese subjects and found –69C〉G polymorphisms of TrkB gene significantly associated with CAD. TrkB –69C homozygotes, which corresponded to decreased TrkB expression by luciferase reporter assay, showed increased risk for CAD. Immunofluorescence analysis revealed that TrkB was expressed in the aortic endothelium in atherosclerotic lesions in humans and ApoE –/– mice. TrkB knockdown in the aortic endothelium resulted in vascular leakage in ApoE –/– mice. Mechanistic studies showed that TrkB regulated vascular endothelial cadherin (VE-cadherin) expression through induction and activation of Ets1 transcriptional factor. Importantly, TrkB activation attenuated proatherosclerotic factors induced-endothelial hyperpermeability in human vascular endothelial cells. Conclusions— Our data demonstrate that TrkB protects endothelial integrity during atherogenesis by promoting Ets1-mediated VE-cadherin expression and plays a previously unknown protective role in the development of CAD.

Description: Rationale : Chronic elevation of 3'-5'-cyclic adenosine monophosphate (cAMP) levels has been associated with cardiac remodeling and cardiac hypertrophy. However, enhancement of particular aspects of cAMP/protein kinase A signaling seems to be beneficial for the failing heart. cAMP is a pleiotropic second messenger with the ability to generate multiple functional outcomes in response to different extracellular stimuli with strict fidelity, a feature that relies on the spatial segregation of the cAMP pathway components in signaling microdomains. Objective : How individual cAMP microdomains affect cardiac pathophysiology remains largely to be established. The cAMP-degrading enzymes phosphodiesterases (PDEs) play a key role in shaping local changes in cAMP. Here we investigated the effect of specific inhibition of selected PDEs on cardiac myocyte hypertrophic growth. Methods and Results : Using pharmacological and genetic manipulation of PDE activity, we found that the rise in cAMP resulting from inhibition of PDE3 and PDE4 induces hypertrophy, whereas increasing cAMP levels via PDE2 inhibition is antihypertrophic. By real-time imaging of cAMP levels in intact myocytes and selective displacement of protein kinase A isoforms, we demonstrate that the antihypertrophic effect of PDE2 inhibition involves the generation of a local pool of cAMP and activation of a protein kinase A type II subset, leading to phosphorylation of the nuclear factor of activated T cells. Conclusions : Different cAMP pools have opposing effects on cardiac myocyte cell size. PDE2 emerges as a novel key regulator of cardiac hypertrophy in vitro and in vivo, and its inhibition may have therapeutic applications.

Description: Objective— Cathepsin S (CatS) participates in atherogenesis through several putative mechanisms. The ability of cathepsins to modify histone tail is likely to contribute to stem cell development. Histone deacetylase 6 (HDAC6) is required in modulating the proliferation and migration of various types of cancer cells. Here, we investigated the cross talk between CatS and HADC6 in injury-related vascular repair in mice. Approach and Results— Ligation injury to the carotid artery in mice increased the CatS expression, and CatS-deficient mice showed reduced neointimal formation in injured arteries. CatS deficiency decreased the phosphorylation levels of p38 mitogen-activated protein kinase, Akt, and HDAC6 and toll-like receptor 2 expression in ligated arteries. The genetic or pharmacological inhibition of CatS also alleviated the increased phosphorylation of p38 mitogen-activated protein kinase, Akt, and HDAC6 induced by platelet-derived growth factor BB in cultured vascular smooth muscle cells (VSMCs), and p38 mitogen-activated protein kinase inhibition and Akt inhibition decreased the phospho-HDAC6 levels. Moreover, CatS inhibition caused decrease in the levels of the HDAC6 activity in VSMCs in response to platelet-derived growth factor BB. The HDAC6 inhibitor tubastatin A downregulated platelet-derived growth factor–induced VSMC proliferation and migration, whereas HDAC6 overexpression exerted the opposite effect. Tubastatin A also decreased the intimal VSMC proliferation and neointimal hyperplasia in response to injury. Toll-like receptor 2 silencing decreased the phosphorylation levels of p38 mitogen-activated protein kinase, Akt, and HDAC6 and VSMC migration and proliferation. Conclusions— This is the first report detailing cross-interaction between toll-like receptor 2–mediated CatS and HDAC6 during injury-related vascular repair. These data suggest that CatS/HDAC6 could be a potential therapeutic target for the control of vascular diseases that are involved in neointimal lesion formation.

Description: Objective— The genetic program underlying lymphatic development is still incompletely understood. This study aims to dissect the role of receptor tyrosine kinase with immunoglobulin-like and EGF (epidermal growth factor)-like domains 1 (Tie1) and Tie2 in lymphatic formation using genetically modified mouse models. Approach and Results— We generated conditional knockout mouse models targeting Tie1, Tie2, and angiopoietin-2 in this study. Tie1 ICD / ICD mice, with its intracellular domain targeted, appeared normal at E10.5 but displayed subcutaneous edema by E13.5. Lymph sac formation occurred in Tie1 ICD / ICD mice, but they had defects with the remodeling of primary lymphatic network to form collecting vessels and valvulogenesis. Consistently, induced deletion of Tie1-ICD postnatally using a ubiquitous Cre deleter led to abnormal lymphangiogenesis and valve formation in Tie1-ICD iUCKO/ – mice. In comparison with the lymphatic phenotype of Tie1 mutants, we found that the diameter of lymphatic capillaries was significantly less in mice deficient of angiopoietin-2, besides the disruption of collecting lymphatic vessel formation as previously reported. There was also no lymphedema observed in Ang2 –/– mice during embryonic development, which differs from that of Tie1 ICD / ICD mice. We further investigated whether Tie1 exerted its function via Tie2 during lymphatic development. To our surprise, genetic deletion of Tie2 ( Tie2 iUCKO/ – ) in neonate mice did not affect lymphatic vessel growth and maturation. Conclusions— In contrast to the important role of Tie2 in the regulation of blood vascular development, Tie1 is crucial in the process of lymphatic remodeling and maturation, which is independent of Tie2.

Description: Rationale: The mammalian target of rapamycin complex 1 inhibitor, rapamycin, has been shown to decrease atherosclerosis, even while increasing plasma low-density lipoprotein levels. This suggests an antiatherogenic effect possibly mediated by the modulation of inflammatory responses in atherosclerotic plaques. Objective: Our aim was to assess the role of macrophage mammalian target of rapamycin complex 1 in atherogenesis. Methods and Results: We transplanted bone marrow from mice in which a key mammalian target of rapamycin complex 1 adaptor, regulatory-associated protein of mTOR, was deleted in macrophages by Cre/loxP recombination ( Mac-Rap KO mice) into Ldlr –/– mice and then fed them the Western-type diet. Atherosclerotic lesions from Mac-Rap KO mice showed decreased infiltration of macrophages, lesion size, and chemokine gene expression compared with control mice. Treatment of macrophages with minimally modified low-density lipoprotein resulted in increased levels of chemokine mRNAs and signal transducer and activator of transcription (STAT) 3 phosphorylation; these effects were reduced in Mac-Rap KO macrophages. Although wild-type and Mac-Rap KO macrophages showed similar STAT3 phosphorylation on Tyr705, Mac-Rap KO macrophages showed decreased STAT3Ser727 phosphorylation in response to minimally modified low-density lipoprotein treatment and decreased Ccl2 promoter binding of STAT3. Conclusions: The results demonstrate cross-talk between nutritionally induced mammalian target of rapamycin complex 1 signaling and minimally modified low-density lipoprotein–mediated inflammatory signaling via combinatorial phosphorylation of STAT3 in macrophages, leading to increased STAT3 activity on the chemokine (C-C motif) ligand 2 (monocyte chemoattractant protein 1) promoter with proatherogenic consequences.

Description: Objective— Phospholipid transfer protein (PLTP) is highly expressed in adipose tissues. Thus, the effect of adipose tissue PLTP on plasma lipoprotein metabolism was examined. Approach and Results— We crossed PLTP-Flox-Neo and adipocyte protein 2 (aP2)-Cre recombinase (Cre) transgenic mice to create PLTP-Flox-Neo/aP2-Cre mice that have a 90 and a 60% reduction in PLTP mRNA in adipose tissue and macrophages, respectively. PLTP ablation resulted in a significant reduction in plasma PLTP activity (22%), high-density lipoprotein-cholesterol (21%), high-density lipoprotein-phospholipid (20%), and apolipoprotein A-I (33%) levels, but had no effect on nonhigh-density lipoprotein levels in comparison with those of PLTP-Flox-Neo controls. To eliminate possible effects of PLTP ablation by macrophages, we lethally irradiated PLTP-Flox-Neo/aP2-Cre mice and PLTP-Flox-Neo mice, and then transplanted wild-type mouse bone marrow into them to create wild-type-〉PLTP-Flox-Neo/aP2-Cre and wild-type-〉PLTP-Flox-Neo mice. Thus, we constructed a mouse model (wild-type-〉PLTP-Flox-Neo/aP2-Cre) with PLTP deficiency in adipocytes but not in macrophages. These knockout mice also showed significant decreases in plasma PLTP activity (19%) and cholesterol (18%), phospholipid (17%), and apolipoprotein A-I (26%) levels. To further investigate the mechanisms behind the reduction in plasma apolipoprotein A-I and high-density lipoprotein lipids, we measured apolipoprotein A-I–mediated cholesterol efflux in adipose tissue explants and found that endogenous and exogenous PLTP significantly increased cholesterol efflux from the explants. Conclusions— Adipocyte PLTP plays a small but significant role in plasma PLTP activity and promotes cholesterol efflux from adipose tissues.

Description: Cathepsin K (CatK) is one of the most potent mammalian collagenases. We showed previously the increased expression of CatK in human and animal atherosclerotic lesions. Here, we hypothesized that ablation of CatK mitigates injury-induced neointimal hyperplasia. Male wild-type (CatK +/+ ) and CatK-deficient (CatK –/– ) mice underwent ligation or a combination of ligation and polyethylene cuff-replacement injuries to the right common carotid artery just proximal to its bifurcation, and they were then processed for morphological and biochemical studies at specific time points. On operative day 28, CatK –/– significantly reduced neointimal formation and neovessel formation in both single- and combination-injured arteries compared with the Cat K +/+ mice. At early time points, CatK –/– reduced the lesion macrophage contents and medial smooth muscle cell proliferation, the mRNA levels of monocyte chemoattractant protein-1, toll-like receptor-2, toll-like receptor-4, chemokine ligand-12, and the gelatinolytic activity related to matrix metalloproteinase-2/-9. An aorta-explant assay revealed that smooth muscle cell movement was impaired in the CatK –/– mice compared with the CatK +/+ mice. In addition, the smooth muscle cells and macrophages from CatK –/– mice had less invasive ability through a reconstituted basement membrane barrier. This vasculoprotective effect was mimicked by Cat inhibition with trans -epoxysuccinyl-L-leucylamido-{4-guanidino} butane (E64 d ). These results demonstrate an essential role of CatK in neointimal lesion formation in response to injury, possibly via the reduction of toll-like receptor-2/-4–mediated inflammation and smooth muscle cell proliferation, suggesting a novel therapeutic strategy for the control of endovascular treatment–related restenosis by regulating CatK activity.

Description: BackgroundGanglionated plexus have been developed as additional ablation targets to improve the outcome of atrial fibrillation (AF) besides pulmonary vein isolation. Recent studies implicated an intimate relationship between neuronal sodium channel Nav1.8 (encoded by SCN10A) and AF. The underlying mechanism between Nav1.8 and AF remains unclear. This study aimed to determine the role of Nav1.8 in cardiac electrophysiology in an acute AF model and explore possible therapeutic targets.Methods and ResultsImmunohistochemical study was used on canine cardiac ganglionated plexus. Both Nav1.5 and Nav1.8 were expressed in ganglionated plexus with canonical neuronal markers. Sixteen canines were randomly administered either saline or the Nav1.8 blocker A‐803467. Electrophysiological study was compared between the 2 groups before and after 6‐hour rapid atrial pacing. Compared with the control group, administration of A‐803467 decreased the incidence of AF (87.5% versus 25.0%, P