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Background and Purpose: Monocyte-derived macrophages are critical in the development of atherosclerosis and can adopt a wide range of functional phenotypes depending on their surrounding milieu. High-density lipoproteins (HDLs) have many cardio-protective properties including potent anti-inflammatory effects. We investigated the effects of HDL on human macrophage phenotype and the mechanisms by which these occur.Experimental Approach: Human blood monocytes were differentiated into macrophages in the presence or absence of HDL and were then induced to either an inflammatory macrophage (M1) or anti-inflammatory macrophage (M2) phenotype using LPS and IFN-γ or IL-4, respectively.Key Results: HDL inhibited the induction of macrophages to an M1-phenotype, as evidenced by a decrease in the expression of M1-specific cell surface markers CD192 and CD64, as well as M1-associated inflammatory genes TNF-α, IL-6 and MCP-1 (CCL2). HDL also inhibited M1 function by reducing the production of ROS. In contrast, HDL had no effect on macrophage induction to the M2-phenotype. Similarly, methyl-β-cyclodextrin, a non-specific cholesterol acceptor also suppressed the induction of M1 suggesting that cholesterol efflux is important in this process. Furthermore, HDL decreased membrane caveolin-1 in M1 macrophages. We confirmed that caveolin-1 is required for HDL to inhibit M1 induction as bone marrow-derived macrophages from caveolin-1 knockout mice continued to polarize into M1-phenotype despite the presence of HDL. Moreover, HDL decreased ERK1/2 and STAT3 phosphorylation in M1 macrophages.Conclusions and Implications: We concluded that HDL reduces the induction of macrophages to the inflammatory M1-phenotype via redistribution of caveolin-1, preventing the activation of ERK1/2 and STAT3. [ABSTRACT FROM AUTHOR]

Background: Circulating microRNAs may represent novel markers for cardiovascular diseases. We evaluated whether circulating miRNAs served as potential biomarkers for diffuse myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM).Methods: Cardiac magnetic resonance imaging with postcontrast T1 mapping was performed to non-invasively quantify diffuse myocardial fibrosis in HCM patients who were classified into two groups (T1 < 470 ms or T1 ≥ 470 ms, as likely or unlikely to have diffuse fibrosis, respectively). First, we screened 84 miRNAs using human serum/plasma miRNA array on plasma of 8 HCM patients (4/group based on T1 time) and 4 healthy controls. From the results of this initial array, 16 miRNAs were selected based on their fold changes and relevance to myocardial fibrosis for further validation by Taqman real-time PCR in 55 HCM patients.Results: Among the 16 miRNAs, the expression of miR-96-5p and miR-373-3p was low. The remaining 14 (miR-18a-5p, miR-146a-5p, miR-30d-5p, miR-17-5p, miR-200a-3p, miR-19b-3p, miR-21-5p, miR-193-5p, miR-10b-5p, miR-15a-5p, miR-192-5p, miR-296-5p, miR-29a-3p, and miR-133a-3p) were upregulated in HCM patients with T1 < 470 ms compared with those with T1 ≥ 470 ms, and 11 (except miR-192-5p, miR-296-5p and miR-133a-3p) were significantly inversely correlated with postcontrast T1 values. Individual miRNA had moderate diagnostic value for diffuse myocardial fibrosis (AUC: 0.663-0.742), but the diagnostic value was greatly improved (AUC: 0.87) for a combination of 8 miRNAs. In comparison, circulating markers of collagen turnover did not have predictive values for diffuse myocardial fibrosis.Conclusions: These findings suggest that circulating miRNAs provide attractive candidates as putative biomarkers for diffuse myocardial fibrosis in HCM. [ABSTRACT FROM AUTHOR]

Background Inflammation plays an important role in the pathogenesis of atherosclerosis. The link between rheumatoid arthritis (RA) and an increased risk of cardiovascular disease and mortality is well established; however, the association between inflammatory bowel disease (IBD) and cardiovascular risk is controversial. Arterial stiffness is both a marker and risk factor for atherosclerosis. Here we aimed to 1) compare circulating markers of inflammation and endothelial dysfunction, traditional cardiovascular risk factors, and arterial stiffness between RA and IBD to help to understand their different associations with cardiovascular disease; 2) assess the impacts of circulating markers of inflammation and endothelial dysfunction, and traditional risk factors on arterial stiffness. Methods Patients with RA (n = 43) and IBD (n = 42), and control subjects (n = 73) were recruited. Plasma inflammatory markers and von Willebrand factor (vWF) were measured by Multiplex assays or ELISA. Arterial stiffness was determined by brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI) was measured. Framingham Risk Score (FRS) was calculated, and other traditional risk factors were also documented. Results Plasma levels of several inflammatory markers and vWF were significantly but comparably elevated in RA and IBD compared with controls, except for a higher level of C-reactive protein (CRP) in RA than IBD. Compared to controls, FRS, body mass index, waist circumference, and triglycerides were increased in RA, but not in IBD. baPWV did not significantly differ among 3 groups, while ABI was modestly but significantly lower in IBD than controls. Circulating markers (macrophage migration inhibitory factor, tumour necrosis factor-α, CRP, and vWF) were significantly associated with baPWV. However, traditional risk factors (age, systolic blood pressure, body mass index, diabetes and triglycerides) were the parameters associated with baPWV in multiple regression analyses (overall r = 0.866, p < 0.001). Conclusions RA has a higher level of CRP and more pronounced traditional cardiovascular risk factors than IBD, which may contribute to the difference in their associations with cardiovascular disease and mortality. Traditional risk factors, rather than inflammation markers, are major predictors of arterial stiffness even in subjects with inflammatory disorders. Our results point to the importance of modifying traditional risk factors in patients with inflammatory disorders. [ABSTRACT FROM AUTHOR]

Purpose: Relaxin, a new drug for heart failure therapy, exerts its cardiac actions through relaxin family peptide receptor 1 (RXFP1). Factors regulating RXFP1 expression remain unknown. We have investigated effects of activation of adrenoceptors (AR), an important modulator in the development and prognosis of heart failure, on expression of RXFP1 in rat cardiomyocytes and mouse left ventricles (LV). Methods: Expression of RXFP1 at mRNA (real-time PCR) and protein levels (immunoblotting) was measured in cardiomyocytes treated with α- and β-AR agonists or antagonists. RXFP1 expression was also determined in the LV of transgenic mouse strains with cardiac-restricted overexpression of α-, α- or β-AR. Specific inhibitors were used to explore signal pathways involved in α-AR mediated regulation of RXFP1 in cardiomyocytes. Results: In cultured cardiomyocytes, α-AR stimulation resulted in 2-3 fold increase in RXFP1 mRNA ( P < 0.001), which was blocked by specific inhibitors for protein kinase C (PKC) or mitogen-activated protein kinases/extracellular signal-regulated kinases (MAPK/ERK). Activation of β-, but not β-AR, significantly inhibited RXFP1 expression ( P < 0.001). Relative to respective wild-type controls, RXFP1 mRNA levels in the LV of mice overexpressing α- or α-AR were increased by 3- or 10-fold, respectively, but unchanged in β-AR transgenic hearts. Upregulation by α-AR stimulation RXFP1 expression was confirmed at protein levels both in vitro and in vivo. Conclusions: Expression of RXFP1 was up-regulated by α-AR but suppressed by β-AR, mainly β-AR subtype, in cardiomyocytes. Future studies are warranted to characterize the functional significance of such regulation, especially in the setting of heart failure. [ABSTRACT FROM AUTHOR]

Aims Plaque rupture partly results from inadequate collagen synthesis due to lower smooth muscle cell numbers in fibrous caps. Fibrocytes are bone-marrow-derived circulating mesenchymal progenitors and have recently been identified in fibrous caps. This study hypothesized that reduced fibrocyte numbers would be associated with plaque instability. Methods and results Patients with acute myocardial infarction (MI) (n = 22), stable angina (SA) (n = 20), or healthy controls (n = 22) were recruited. Circulating fibrocytes (CD45+/CD34+/collagen I+) were measured by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from blood and cultured for 2 weeks, and fibrocytes were quantified by morphology (spindle-shaped) and flow cytometry (CD45+/collagen I+). Another set of PBMCs was stimulated with macrophage colony-stimulating factor (M-CSF) for 72 h and the expression of several macrophage markers was measured by flow cytometry. Acute MI patients had decreased circulating fibrocyte numbers compared with healthy controls or SA patients. Following 2 weeks' culture, both the number of spindle-shaped fibrocytes counted under the microscope and the percentage of fibrocytes of the remaining adherent cells in culture measured by flow cytometry were reduced in acute MI patients. Expression of macrophage markers CD68, CD36, and EMR in M-CSF-stimulated PBMCs was enhanced in acute MI patients compared with the other two groups. SA patients with previous MI had decreased circulating fibrocyte numbers and a lower yield of fibrocytes from PBMCs than those without previous MI. Conclusions This is the first report of decreased fibrocyte numbers in patients with MI. Reduced fibrocytes and preferential differentiation of PBMCs into macrophages may contribute to plaque instability. [ABSTRACT FROM AUTHOR]

As a hallmark of heart disease, cardiac fibrosis contributes to the development of heart failure and arrhythmias and forms a key therapeutic target. There is a major unmet need for selective, potent, and safe antifibrotic drugs. Earlier studies revealed a cardiac fibrosis phenotype in relaxin-1-deficient mice. Recent studies in several rodent models of cardiac fibrosis have documented reversal of fibrosis by treatment with relaxin peptide or virally mediated relaxin gene delivery. In mice with surgically induced transmural myocardial infarction, relaxin therapy inhibited scar density. In these studies, however, functional benefits achieved by relaxin therapy were limited or less explored. Collectively, there is good experimental evidence that relaxin is able to reverse cardiac fibrosis due to distinct mechanisms. Future research needs to explore functional improvement following fibrosis reversal by relaxin and the usefulness of relaxin in antiarrhythmic or stem cell-based therapy. [ABSTRACT FROM AUTHOR]

Although RXFP1-cAMP signaling in HEK293T cell systems is now relatively well-defined, the signaling pathways activated by relaxin in its target cells and tissues are still unclear. This study aimed to examine the cAMP signaling of RXFP1 in cells that endogenously express the receptor. Seven cell types derived from various backgrounds were screened for receptor expression. Only in THP-1 cells and rat cardiac fibroblasts was there activation of the Gαi3–Gβγ–phosphatidylinositol 3-kinase–protein kinase Cζ pathway, leading to cAMP accumulation. In all other cells there was activation of a combination of the initial pathways to affect cAMP. T-47D cells could activate only Gαs, whereas Colo 16 and rat renal fibroblasts from obstructed kidney could activate both Gαs and GαoB pathways. Thus, the signaling pathways activated by relaxin are highly dependent upon the cell type under investigation, and this may help to explain the varied physiological responses exerted by relaxin in its different target tissues. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Myocardial contractility is enhanced in transgenic (TG) mice with cardiac-restricted overexpression of the α1A-adrenergic receptors (α1A-AR). We tested the hypothesis that this enhanced inotropy protects against dysfunction and remodeling after myocardial infarction (MI). Methods: We subjected α1A-TG and non-TG mice (NTG) to MI and determined changes in left ventricular (LV) function and diastolic dimension (LVDd) by echocardiography prior to and at 1, 3, 7, 12 and 15 weeks thereafter. Results: Although infarct size was similar in the NTG and α1A-TG groups (32±2 vs. 29±2% of LV, P =NS), mortality due to heart failure was lower after MI in the α1A-TG (37%, n =39) than that in the NTG animals (63%, n =56, P =0.026). NTG and α1A-TG mice showed similar reductions in LV fractional shortening (FS) and increases in LVDd at week-1 after MI. However, whereas NTG mice showed continuous deterioration over a 15-week period after MI in FS (fell by 40%, from 30±2 to 18±1%, P <0.01) and LVDd (increased by 24%, from 4.2±0.1 to 5.2±0.1 mm, P <0.01), the changes in both FS (fell by 14%, from 42±2 to 36±2%) and LVDd (increased by 8%, from 3.8±0.1 to 4.1±0.1 mm, both changes P <0.01 vs. NTG) were significantly less severe in the α1A-TG mice and did not progress after 3 weeks. At 15 weeks after MI, LV catheterization revealed better preservation of dP/dt max in the α1A-TG vs. NTG mice (7270±324, vs. 5938±372 mmHg/s, P <0.05). Conclusion: Enhanced inotropy resulting from transgenic overexpression of α1A-AR is well maintained chronically after MI and limits echocardiography-determined LV remodeling, preserves function, and reduces acute heart failure death. [Copyright &y& Elsevier]

Cardiac RXFP1 was upregulated upon activation of the α1-adrenergic receptor (AR) through signal pathways involving protein kinase A and C and ERK. In contrast, β1-AR activation downregulated expression of cardiac RXFP1 and it further counteracted the α1-AR-mediated RXFP1 upregulation. [ABSTRACT FROM AUTHOR]