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Pressure-overload-induced cardiac hypertrophy represents one cause of the development of heart failure. The aim of this study is to characterize the influence of the TIR-domain-containing adapter-inducing interferon-β (TRIF) during afterload-induced myocardial remodeling. After trans-aortic constriction (TAC), cardiac pressure overload leads to an early increase in MyD88- (Myeloid differentiation primary response gene 88) and TRIF-dependent cytokines. The maximum cytokine expression appeared within the first week and decreased to its control level within five weeks. While cardiomyocyte hypertrophy was comparable, the myocardial accumulation of the inflammatory cells was lower in TRIF−/−mice. At d7, TRIF deficiency reduced transcription factors and TRIF-dependent cytokines. Through the modulation of the TGF-β-signaling pathway and anti-fibrotic microRNAs, TRIF was involved in the development of interstitial fibrosis. The absence of TRIF was associated with a decreased expression of proapoptotic proteins. In echocardiography and working heart analyses, TRIF deficiency slowed left-ventricular wall thickening, myocardial hypertrophy, and reduces the ejection fraction. In summary, TRIF is an important adapter protein for the release of inflammatory cytokines and the accumulation of inflammatory cells in the early stage of maladaptive cardiac remodeling. TRIF is involved in the development of cardiac fibrosis by modulating inflammatory and fibrotic signal transduction pathways. [ABSTRACT FROM AUTHOR]

Background Since kidney transplant recipients (KTRs) have a high cardiovascular disease burden, adequate risk prediction is of importance. Whether echocardiographic parameters and plasma biomarkers, natriuretic peptides [N-terminal pro-B-type natriuretic peptide (NT-proBNP)] and troponin T provide complementary or overlapping prognostic information on cardiovascular events remains uncertain. Methods The prospective Heterogeneity of Monocytes and Echocardiography Among Allograft Recipients in Nephrology (HOME ALONE) study followed 177 KTRs for 5.4 ± 1.7 years. Predefined endpoints were hospitalization for acute decompensated heart failure or all-cause death (HF/D) and major atherosclerotic cardiovascular events or all-cause death (MACE/D). At baseline, plasma NT-proBNP, plasma troponin T and echocardiographic parameters [left atrial volume index, left ventricular (LV) mass index, LV ejection fraction, and LV filling pressure] were assessed. Results Among all echocardiographic and plasma biomarkers measured, only NT-proBNP was consistently associated with HF/D in univariate and multivariate {third versus first tertile: hazard ratio [HR] 4.20 [95% confidence interval (CI) 1.02–17.27]} analysis, and only troponin T was consistently associated with MACE/D in univariate and multivariate [third versus first tertile: HR 8.15 (95% CI 2.75–24.18)] analysis. Conclusion Our data suggest that plasma biomarkers are robust and independent predictors of heart failure and atherosclerotic cardiovascular events after kidney transplantation, whereas standard echocardiographic follow-up does not add to risk prediction. [ABSTRACT FROM AUTHOR]

The specific antagonists of tumor necrosis factor-[alpha] (TNF-[alpha]), infliximab and etanercept, are established therapeutic agents for inflammatory diseases such as rheumatoid arthritis and Crohn's disease. Although the importance of TNF-[alpha] in chronic inflammatory diseases is well established, little is known about its implications in the cardiovascular system. Because proliferation of arteriolar connections toward functional collateral arteries (arteriogenesis) is an inflammatory-like process, we tested in vivo the hypothesis that infliximab and etanercept have antiarteriogenic actions. Sixty-three New Zealand White rabbits underwent femoral artery occlusion and received infliximab, etanercept, or vehicle according to clinical dosage regimes. After 1 wk, collateral conductance, assessed with fluorescent microspheres, revealed significant inhibition of arteriogenesis (collateral conductance): 52.4 (SD 8.1), 35.2 (SD 7.7), and 33.3 (SD 10.1) ml x [min.sup.-1] x 100 [mmHg.sup.-1] with PBS, infliximab, and etanercept, respectively (P < 0.001). High: resolution angiography showed no significant differences in number of collateral arteries, but immunohistochemical analysis demonstrated a decrease in mean collateral diameter, proliferation of vascular smooth muscle cells, and reduction of leukocyte accumulation around collateral arteries in treated groups. Infliximab and etanercept bound to infiltrating leukocytes, which are important mediators of arteriogenesis. Infliximab induced monocyte apoptosis, and neither substance affected monocyte expression of the adhesion molecule Mac-1. We demonstrated that TNF-[alpha] serves as a pivotal modulator of arteriogenesis, which is attenuated by treatment with TNF-[alpha] inhibitors. Reduction of collateral conductance is most likely due to inhibition of perivascular leukocyte infiltration and subsequent lower vascular smooth muscle cell proliferation. This is the first report showing a negative influence of TNF-[alpha] inhibitors on collateral artery growth. collateral circulation; growth factors

Abstract Background Circulating CD34+ progenitor cells have the potential to differentiate into a variety of cells, including endothelial cells. Knowledge is still scarce about the transcriptional programs used by CD34+ cells from peripheral blood, and how these are affected in coronary artery disease (CAD) patients. Results We performed a whole genome transcriptome analysis of CD34+ cells, CD4+ T cells, CD14+ monocytes, and macrophages from 12 patients with CAD and 11 matched controls. CD34+ cells, compared to other mononuclear cells from the same individuals, showed high levels of KRAB box transcription factors, known to be involved in gene silencing. This correlated with high expression levels in CD34+ cells for the progenitor markers HOXA5 and HOXA9, which are known to control expression of KRAB factor genes. The comparison of expression profiles of CD34+ cells from CAD patients and controls revealed a less naïve phenotype in patients' CD34+ cells, with increased expression of genes from the Mitogen Activated Kinase network and a lowered expression of a panel of histone genes, reaching levels comparable to that in more differentiated circulating cells. Furthermore, we observed a reduced expression of several genes involved in CXCR4-signaling and migration to SDF1/CXCL12. Conclusions The altered gene expression profile of CD34+ cells in CAD patients was related to activation/differentiation by a retinoic acid-induced differentiation program. These results suggest that circulating CD34+ cells in CAD patients are programmed by retinoic acid, leading to a reduced capacity to migrate to ischemic tissues.

Aims Unicuspid aortic valve (UAV) is a rare congenital malformation associated with severe aortic stenosis or regurgitation. This study aimed to systematically determine echocardiographic criteria to identify UAV. Methods and results All patients underwent a preoperative baseline examination, including echocardiography. A total of 69 patients with intraoperatively confirmed UAV underwent an aortic valve repair procedure between August 2001 and May 2011. To compare the findings of UAV cases with those of other valve morphologies, we examined 99 consecutive patients with a bicuspid aortic valve (BAV) and 103 consecutive patients with a tricuspid aortic valve (TAV) undergoing isolated aortic valve surgery before May 2016. The mean age of the 271 patients was 44.2 ± 12.8 years; 85% were male, with a mean body mass index of 26.2 ± 4.0 kg/m2. Patients with UAV were younger and had fewer co-morbidities than patients with BAV or TAV, respectively. The major criteria for the echocardiographic diagnosis of UAV were defined based on our preoperative examination as follows: (i) single commissural attachment zone, (ii) rounded, leaflet-free edge on the opposite side of the commissural attachment zone, (iii) eccentric valvular orifice during systole, and (iv) patient age <20 years and mean transvalvular gradient >15 mmHg. The minor criteria were defined as an associated thoracic aortopathy and age <40 years. Three out of the four major criteria or two out of the four major criteria and one minor criterion were met in all patients with UAV and in none of the patients with BAV or TAV. Associated 95% confidence intervals were calculated for each estimate of sensitivity (94.7–100%) and specificity (98.1–100%), indicating that an adequate number of patients were included in each of the three groups. Conclusion The proposed echocardiographic score appears to be a specific and sensitive method to distinguish UAV from BAV and TAV. [ABSTRACT FROM AUTHOR]

Abstract: Secondary mitral regurgitation (MR) results from left ventricular dilatation and dysfunction. Quantification of secondary MR is challenging because of the underlying myocardial disease. Clinical and echocardiographic evaluation requires a multi‐parametric approach. Severe secondary MR occurs in up to one‐fourth of patients with heart failure with reduced ejection fraction, which is associated with a mortality rate of 40% to 50% in 3 years. Percutaneous edge‐to‐edge mitral valve repair (MitraClip) has emerged as an alternative to surgical valve repair to improve symptoms, functional capacity, heart failure hospitalizations, and cardiac haemodynamics. Further new transcatheter strategies addressing MR are evolving. The Carillion, Cardioband, and Mitralign devices were designed to reduce the annulus dilatation, which is a frequent and important determinant of secondary MR. Several transcatheter mitral valve replacement systems (Tendyne, CardiAQ‐Edwards, Neovasc, Tiara, Intrepid, Caisson, HighLife, MValve System, and NCSI NaviGate Mitral) are emerging because valve replacement might be more durable compared with valve repair. In small studies, these interventional therapies demonstrated feasibility and efficiency to reduce MR and to improve heart failure symptoms. However, neither transcatheter nor surgical mitral valve repair or replacement has been proven to impact on the prognosis of heart failure patients with severe MR, which remains high with a mortality rate of 14–20% at 1 year. To date, the primary indication for treatment of secondary severe MR is the amelioration of symptoms, reinforcing the value of a Heart Team discussion. Randomized studies to investigate the treatment effect and long‐term outcome for any transcatheter or surgical mitral valve intervention compared with optimized medical treatment are urgently needed and underway. [ABSTRACT FROM AUTHOR]

Background: Cardiological societies recommend, in their guidelines, that patients with atrial fibrillation and an intermediate (or higher) risk of stroke and systemic embolization should be treated with oral anticoagulant drugs. For patients who do not have mitral valve stenosis or a mechanical valve prosthesis, non-vitamin-K dependent oral anticoagulants (NOAC) are preferred over vitamin K antagonists (VKA) for this purpose. It is unclear, however, whether patients with chronic kidney disease and atrial fibrillation benefit from oral anticoagulation to the same extent as those with normal kidney function. It is also unclear which of the two types of anti - coagulant drug is preferable for patients with chronic kidney disease; NOAC are, in part, renally eliminated. Methods: This review is based on pertinent publications retrieved by a selective literature search, and on international guidelines. Results: Current evidence suggests that patients with atrial fibrillation who have chronic kidney disease with a glomerular filtration rate (GFR) above 15 mL/ min/1.73 m² should be treated with an oral anticoagulant drug if they have an at least intermediate risk of embolization, as assessed with the CHA2DS2-VASc score. For patients with advanced chronic kidney disease (GFR from 15 to 29 mL/ min/1.73 m²), however, this recommendation is based only on registry studies. For dialysis patients with atrial fibrillation, decisions whether to give oral anticoagulant drugs should be taken on an individual basis, in view of the elevated risk of hemorrhage and the unclear efficacy of such drugs in these patients. The subgroup analyses of the NOAC approval studies show that, for patients with atrial fibrillation and chronic kidney disease with a creatinine clearance of >25-30 mL/min, NOAC should be given in preference to VKA, as long as the patient does not have mitral valve stenosis or a mechanical valve prosthesis. For those whose creatinine clearance is less than 25 mL/min, the relative merits of NOAC versus VKA are still debated. Conclusion: The cardiological societies' recommendation that patients with atrial fibrillation should be given oral anticoagulant drugs applies to the majority of such patients who also have chronic kidney disease. [ABSTRACT FROM AUTHOR]

Background: Apolipoprotein E-deficient (ApoE(-/-)) rodents spontaneously develop severe hypercholesterolemia and increased aortic stiffness, both accepted risk factors for cardiovascular morbidity and mortality in humans. In patients with resistant hypertension renal denervation (RDN) may improve arterial stiffness, however the underlying mechanisms are incompletely understood. This study investigates the impact of RDN on aortic compliance in a novel atherosclerosis prone ApoE(-/-)-rat model.Methods: Normotensive, 8 weeks old ApoE(-/-) and Sprague-Dawley (SD) rats were subjected to bilateral surgical RDN (n = 6 per group) or sham operation (n = 5 per group) and fed with normal chow for 8 weeks. Compliance of the ascending aorta was assessed by magnetic resonance imaging. Vasomotor function was measured by aortic ring tension recordings. Aortic collagen content was quantified histologically and plasma aldosterone levels were measured by enzyme-linked immunosorbent assay (ELISA).Results: After 8 weeks, ApoE(-/-)-sham demonstrated a 58 % decrease in aortic distensibility when compared with SD-sham (0.0051 ± 0.0011 vs. 0.0126 ± 0.0023 1/mmHg; p = 0.02). This was accompanied by an impaired endothelium-dependent relaxation of aortic rings and an increase in aortic medial fibrosis (17.87 ± 1.4 vs. 12.27 ± 1.1 %; p = 0.006). In ApoE(-/-)-rats, RDN prevented the reduction of aortic distensibility (0.0128 ± 0.002 vs. 0.0051 ± 0.0011 1/mmHg; p = 0.01), attenuated endothelial dysfunction, and decreased aortic medial collagen content (12.71 ± 1.3 vs. 17.87 ± 1.4 %; p = 0.01) as well as plasma aldosterone levels (136.33 ± 6.6 vs. 75.52 ± 8.4 pg/ml; p = 0.0003). Cardiac function and metabolic parameters such as hypercholesterolemia were not influenced by RDN.Conclusion: ApoE(-/-)-rats spontaneously develop impaired vascular compliance. RDN improves aortic distensibility and attenuated endothelial dysfunction in ApoE(-/-)-rats. This was associated with a reduction in aortic fibrosis formation, and plasma aldosterone levels. [ABSTRACT FROM AUTHOR]

Background: Coronary collateral arteries function as natural bypasses in the event of coronary obstruction. The degree of collateral network development significantly impacts the outcome of patients after an acute myocardial infarction (AMI). MicroRNAs (miRNAs, miRs) have arisen as biomarkers to identify heterogeneous patients, as well as new therapeutic targets in cardiovascular disease. We sought to identify miRNAs that are differentially expressed in chronic total occlusion (CTO) patients with well or poorly developed collateral arteries. Methods and Results: Forty-one CTO patients undergoing coronary angiography and invasive assessment of their coronary collateralization were dichotomized based on their collateral flow index (CFI). After miRNA profiling was conducted on aortic plasma, four miRNAs were selected for validation by real-time quantitative reverse transcription polymerase chain reaction in patients with low (CFI<0.39) and high (CFI>0.39) collateral artery capacity. We confirmed significantly elevated levels of miR423-5p (p<0.05), miR10b (p<0.05), miR30d (p<0.05) and miR126 (p<0.001) in patients with insufficient collateral network development. We further demonstrated that each of these miRNAs could serve as circulating biomarkers to discriminate patients with low collateral capacity (p<0.01 for each miRNA). We also determined significantly greater expression of miR30d (p<0.05) and miR126 (p<0.001) in CTO patients relative to healthy controls. Conclusion: The present study identifies differentially expressed miRNAs in patients with high versus low coronary collateral capacity. We have shown that these miRNAs can function as circulating biomarkers to discriminate between patients with insufficient or sufficient collateralization. This is the first study to identify miRNAs linked to coronary collateral vessel function in humans. [ABSTRACT FROM AUTHOR]

BACKGROUND Obstructive sleep apnea (OSA) is associated with hypertension and the progression of chronic kidney disease (CKD). Renal sympathetic innervation contributes to either condition. METHODS We investigated the effect of renal sympathetic denervation (RDN) on blood pressure (BP), renal perfusion, and neurohumoral responses during and after repetitive obstructive apneas in a pig model for OSA. BP, femoral artery, and renal artery flow were measured in 29 spontaneously breathing urethane-chloralose–anesthetized pigs. The effect of RDN (n = 14) and irbesartan (n = 3) was investigated. Repetitive tracheal occlusions for 2 minutes with applied negative tracheal pressure at −80 mbar were performed over 4 hours. RESULTS Spontaneous breathing attempts during tracheal occlusion caused an intra-apneic breathing synchronous oscillating pattern of renal flow. Renal flow oscillations were >2-fold higher compared with femoral flow that almost showed changes proportional to the BP alterations (2.9%/mm Hg vs. 1.3%/mm Hg; P < 0.0001). A marked postapneic BP rise from 102±3 to 172±8 mm Hg (P < 0.00001) was associated with renal hypoperfusion (from 190±24 to 70±20ml/min; P < 0.00001) occurring after application of obstructive respiratory events. RDN, but not irbesartan, inhibited postapneic BP rises and renal hypoperfusion and attenuated increased plasma renin activity and aldosterone concentration induced by repetitive tracheal occlusions. Additionally, increased urinary protein/creatinine ratio was significantly reduced by RDN, whereas intra-apneic hemodynamic changes or blood gases were not modified by RDN. CONCLUSIONS Repetitive obstructive respiratory events result in postapneic BP rises and renal hypoperfusion, as well as neurohumoral responses and increased protein/creatinine ratio. These changes are mainly sympathetically driven because they could be attenuated by RDN. [ABSTRACT FROM AUTHOR]

Objectives: This study sought to investigate the interaction between blood pressure (BP) and heart rate (HR) reduction and changes in left ventricular (LV) structure and function following renal sympathetic denervation (RDN). Background: Hypertension results in structural and functional cardiac changes. RDN reduces BP, HR, and LV mass and improves diastolic dysfunction. Methods: We evaluated LV size, mass, and function before and 6 months after RDN in 66 patients with resistant hypertension and analyzed results in relation to systolic BP (SBP) and HR. Results: SBP decreased by 11 ± 3 mm Hg in the first, 18 ± 5 mm Hg in the second, and 36 ± 7 mm Hg in the third tertile of SBP at baseline (p < 0.001). HR decreased by 13 ± 4 beats/min, 8 ± 3 beats/min, and 11 ± 6 beats/min in tertiles of SBP (p for interaction between tertiles = 0.314). In all SBP tertiles, LV mass index (LVMI) decreased similarly (LVMI −6.3 ± 2.2 g/m2.7, −8.3 ± 2.1 g/m2.7, and −9.6 ± 1.9 g/m2.7; p for interaction = 0.639). LVMI decreased unrelated to HR at baseline (p for interaction = 0.471). The diastolic parameters E-wave deceleration time, isovolumetric relaxation time, and E′-wave velocity improved similarly in all tertiles of SBP and HR. Changes in LV mass and function were also unrelated to reduction in SBP or HR. Vascular compliance improved dependently on BP but independently of HR reduction. Conclusions: In patients with resistant hypertension, LV hypertrophy and diastolic function improved 6 months after RDN, without significant relation to SBP and HR. These findings suggest a direct effect of altered sympathetic activity in addition to unloading on cardiac hypertrophy and function. [ABSTRACT FROM AUTHOR]

Inflammation and fibrosis play an important pathophysiological role in chronic kidney disease (CKD), with pro-inflammatory mediators and leukocytes promoting organ damage with subsequent fibrosis. Since chemokines are the main regulators of leukocyte chemotaxis and tissue inflammation, we performed systemic chemokine profiling in early CKD in mice. This revealed (C-C motif) ligands 6 and 9 (CCL6 and CCL9) as the most upregulated chemokines, with significantly higher levels of both chemokines in blood (CCL6: 3–4 fold; CCL9: 3–5 fold) as well as kidney as confirmed by Enzyme-linked Immunosorbent Assay (ELISA) in two additional CKD models. Chemokine treatment in a mouse model of early adenine-induced CKD almost completely abolished the CKD-induced infiltration of macrophages and myeloid cells in the kidney without impact on circulating leukocyte numbers. The other way around, especially CCL9-blockade aggravated monocyte and macrophage accumulation in kidney during CKD development, without impact on the ratio of M1-to-M2 macrophages. In parallel, CCL9-blockade raised serum creatinine and urea levels as readouts of kidney dysfunction. It also exacerbated CKD-induced expression of collagen (3.2-fold) and the pro-inflammatory chemokines CCL2 (1.8-fold) and CCL3 (2.1-fold) in kidney. Altogether, this study reveals for the first time that chemokines CCL6 and CCL9 are upregulated early in experimental CKD, with CCL9-blockade during CKD initiation enhancing kidney inflammation and fibrosis. [ABSTRACT FROM AUTHOR]

The coronary arteries have been regarded as end arteries for decades. However, there are functionally relevant anastomotic vessels, known as collateral arteries, which interconnect epicardial coronary arteries. These vessels provide an alternative source of blood supply to the myocardium in cases of occlusive coronary artery disease. The relevance of these collateral arteries is a matter of ongoing debate, but increasing evidence indicates a relevant protective role in patients with coronary artery disease. The collateral circulation can be assessed by different methods; the gold standard involves intracoronary pressure measurements. While the first clinical trials to therapeutically induce growth of collateral arteries have been unavailing, recent pilot studies using external counterpulsation or growth factors such as granulocyte colony stimulating factor (G-CSF) have shown promising results. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Epidemiologic studies suggest that elevated postprandial triglycerides (ppTG) are associated with future cardiovascular events. Monocyte activation plays an important role in vascular diseases. Omega-3 fatty acids (n3-FA) lower fasting TG levels. The effects of n3-FA on ppTG and the role of ppTG for monocyte activation are insufficiently understood. Methods and results: 23 healthy volunteers and 30 non-diabetic patients with documented coronary artery disease were subjected to an oral TG tolerance test (OTTT) consisting of 80 g cream fat or to water as control (H2O). Patients were treated with 4 g n3-FA/day or placebo for 3 weeks in a randomized, placebo-controlled, double-blind, crossover study. Relative postprandial TG increase reached its maximum 4 h after fat intake (185.1 ± 10.9% of baseline). n3-FA reduced fasting TG from 137.1 ± 12.9 to 112.2 ± 8.6 mg/dl (p < 0.05), and maximum ppTG concentrations from 243.6 ± 24.6 to 205.8 ± 17.1 mg/dl (p < 0.05), while relative TG increase (192.8 ± 12.7%) was comparable to placebo. Relative monocytopenia and neutrophilia were detected following fat intake, which was unaffected by n3-FA and also detectable in the H2O group. Serum chemotactic cytokine (MCP1 and fractalkine) concentrations and monocyte migration were not affected by fat intake or n3-FA. Monocyte activation markers CD11b and CD14, monocyte subpopulations CD16+CD14high and CD16+CD14low, sICAM serum levels and markers of oxidative stress remained unchanged by fat intake or n3-FA. Conclusion: The postprandial TG increase does not stimulate monocytes beyond their circadian activation patterns. n3-FA reduce fasting TG and the postprandial TG increase. n3-FA may therefore allow to prospectively study whether selected patients benefit from TG-lowering independent of LDL- and HDL-cholesterol. [Copyright &y& Elsevier]

Atrial fibrillation (AF) is the most common cardiac rhythm disorder and a major risk factor for ischemic stroke. Antithrombotic therapy using aspirin or vitamin K antagonists (VKA) is currently prescribed for prevention for ischemic stroke in patients with AF. A narrow therapeutic range and the need of regular monitoring of its anticoagulatory effect impair effectiveness and safety of VKA, causing a need for alternative anticoagulant drugs. Recently developed anticoagulants include direct thrombin antagonists such as dabigatran or factor Xa inhibitors such as rivaroxaban, apixaban, betrixaban, and edoxaban. Currently, data from a phase III clinical trial are available for dabigatran only, which show the direct thrombin antagonist to be at least noninferior in efficacy to VKA for the prevention of stroke and systemic embolism in patients with AF. This review focuses on current advances in the development of directly acting oral anticoagulant drugs and their potential to replace the VKA class of drugs in patients with AF. [ABSTRACT FROM AUTHOR]

This review summarizes the current literature and the open questions regarding the physiology and pathophysiology of the mechanical effects of heart rate on the vessel wall and the associated molecular signaling that may have implications for patient care. Epidemiological evidence shows that resting heart rate is associated with cardiovascular morbidity and mortality in the general population and in patients with cardiovascular disease. As a consequence, increased resting heart rate has emerged as an independent risk factor both in primary prevention and in patients with hypertension, coronary artery disease, and myocardial infarction. Experimental and clinical data suggest that sustained elevation of heart rate—independent of the underlying trigger—contributes to the pathogenesis of vascular disease. In animal studies, accelerated heart rate is associated with cellular signaling events leading to vascular oxidative stress, endothelial dysfunction, and acceleration of atherogenesis. The underlying mechanisms are only partially understood and appear to involve alterations of mechanic properties such as reduction of vascular compliance. Clinical studies reported a positive correlation between increased resting heart rate and circulating markers of inflammation. In patients with coronary heart disease, increased resting heart rate may influence the clinical course of atherosclerotic disease by facilitation of plaque disruption and progression of coronary atherosclerosis. While a benefit of pharmacological or interventional heart rate reduction on different vascular outcomes was observed in experimental studies, prospective clinical data are limited, and prospective evidence determining whether modulation of heart rate can reduce cardiovascular events in different patient populations is needed. [ABSTRACT FROM AUTHOR]

Increased interferon (IFN)-β signaling in patients with insufficient coronary collateralization and an inhibitory effect of IFNβ on collateral artery growth in mice have been reported. The mechanisms of IFNβ-induced inhibition of arteriogenesis are unknown. In stimulated monocytes from patients with chronic total coronary artery occlusion and decreased arteriogenic response, whole genome expression analysis showed increased expression of IFNβ-regulated genes. Immunohistochemically, the IFNβ receptor was localized in the vascular media of murine collateral arteries. Treatment of vascular smooth muscle cells (VSMC) with IFNβ resulted in an attenuated proliferation, cell-cycle arrest, and increased expression of cyclin-dependent kinase inhibitor-1A (p21). The growth inhibitory effect of IFNβ was attenuated by inhibition of p21 by RNA interference. IFNβ-treated THP1 monocytes showed enhanced apoptosis. Subsequently, we tested if collateral artery growth can be stimulated by inhibition of IFNβ-signaling. RNA interference of the IFNβ receptor-1 (IFNAR1) increased VSMC proliferation, cell cycle progression, and reduced p21 gene expression. IFNβ signaling and FAS and TRAIL expression were attenuated in monocytes from IFNAR1-/- mice, indicating reduced monocyte apoptosis. Hindlimb perfusion restoration 1 week after femoral artery ligation was improved in IFNAR1-/- mice compared with wild-type mice as assessed by infusion of fluorescent microspheres. These results demonstrate that IFNβ inhibits collateral artery growth and VSMC proliferation through p21-dependent cell cycle arrest and induction of monocyte apoptosis. Inhibition of IFNβ stimulates VSMC proliferation and collateral artery growth. [ABSTRACT FROM AUTHOR]