Interplay Between Plasma Glycine and Branched-Chain Amino Acids Contributes to the Development of Hypertension and Coronary Heart Disease.

BACKGROUND: Higher levels of plasma glycine are linked to a reduced risk, while increased levels of total branched-chain amino acids (tBCAAs) are associated with a higher risk of essential hypertension (HTN) and coronary heart disease (CHD). As these metabolic components are interconnected, analyzing the tBCAAs/glycine ratio may help to understand their interplay in the pathogenesis of cardiovascular disease. METHODS: The Cox regression approach was combined with the development of novel genetic tools for assessments of associations between plasma metabolomic data (glycine, tBCAAs, and tBCAAs/glycine ratio) from the UK Biobank and the development of hypertension and CHD. Genome-wide association study was performed on 186 523 White UK Biobank participants to identify new independent genetic instruments for the 2-sample Mendelian randomization analyses. P-gain statistic >10 identified instruments associated with tBCAAs/glycine ratio significantly stronger compared with individual amino acids. Outcomes of genome-wide association study on hypertension and CHD were derived from the UK Biobank (nonoverlapping sample), FinnGen, and CARDIoGRAMplusC4D. RESULTS: The tBCAAs/glycine ratio was prospectively associated with a higher risk of developing hypertension and CHD (hazard ratio quintile, Q5 versus Q1, 1.196 [95% CI, 1.109-1.289] and 1.1226 [95% CI, 1.160-1.1296], respectively). Mendelian randomization analysis demonstrated that tBCAAs/glycine ratio (P-gain >10) was a risk factor for hypertension (meta-analyzed inverse-variance weighted causal estimate 0.45 log odds ratio/SD (95% CI, 0.26-0.64) and CHD (0.48 [95% CI, 0.29-0.67]) with an absolute effect significantly larger compared with the effect of glycine (-0.06 [95% CI, -0.1 to -0.03] and -0.08 [95% CI, -0.11 to -0.05], respectively) or tBCAAs (0.22 95% CI, 0.09-0.34] and 0.12 [95% CI, 0.01-0.24], respectively). CONCLUSIONS: The total BCAAs/glycine ratio is a key element of the metabolic signature contributing to hypertension and CHD, which may reflect biological pathways shared by glycine and tBCAAs.

Systemic and local vascular inflammation and arterial reactive oxygen species generation in patients with advanced cardiovascular diseases.

Background: Systemic inflammation may cause endothelial activation, mediate local inflammation, and accelerate progression of atherosclerosis. We examined whether the levels of circulating inflammatory cytokines reflect local vascular inflammation and oxidative stress in two types of human arteries. Methods: Human internal mammary artery (IMA) was obtained in 69 patients undergoing coronary artery bypass graft (CABG) surgery and left anterior descending (LAD) artery was obtained in 17 patients undergoing heart transplantation (HTx). Plasma levels of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) were measured using ELISA, high-sensitivity C-reactive protein (hs-CRP) was measured using Luminex, and mRNA expression of proinflammatory cytokines in the vascular tissues was assessed. Furthermore, formation of superoxide anion was measured in segments of IMA using 5 uM lucigenin-dependent chemiluminescence. Vascular reactivity was measured using tissue organ bath system. Results: TNF-α, IL-6 and IL-1ß mRNAs were expressed in all studied IMA and LAD segments. Plasma levels of inflammatory cytokines did not correlate with vascular cytokine mRNA expression neither in IMA nor in LAD. Plasma TNF-α and IL-6 correlated with hs-CRP level in CABG group. Hs-CRP also correlated with TNF-α in HTx group. Neither vascular TNF-α, IL-6 and IL-1ß mRNA expression, nor systemic levels of either TNF-α, IL-6 and IL-1ß were correlated with superoxide generation in IMAs. Interestingly, circulating IL-1ß negatively correlated with maximal relaxation of the internal mammary artery (r = -0.37, p = 0.004). At the same time the mRNA expression of studied inflammatory cytokines were positively associated with each other in both IMA and LAD. The positive correlations were observed between circulating levels of IL-6 and TNF-α in CABG cohort and IL-6 and IL-1ß in HTx cohort. Conclusions: This study shows that peripheral inflammatory cytokine measurements may not reflect local vascular inflammation or oxidative stress in patients with advanced cardiovascular disease (CVD). Circulating pro-inflammatory cytokines generally correlated positively with each other, similarly their mRNA correlated in the arterial wall, however, these levels were not correlated between the studied compartments.

Novel biomarkers and emerging tools to identify causal molecular pathways in hypertension and associated cardiovascular diseases.

Hypertension (HT) is a modifiable risk factor for life-threatening cardiovascular diseases (CVDs) including coronary artery disease, heart failure, or stroke. Despite significant progress in understanding the pathophysiological mechanisms of the disease, the molecular pathways targeted by HT treatment remain largely unchanged. This warrants the need for finding novel biomarkers, which are causally related to persistent high blood pressure (BP) and may be pharmacologically targeted. Analytical output derived from large-scale biobanks, containing high-throughput genetic and biochemical data, such as OLINK and SomaScan-based proteomics or Nuclear Magnetic Resonance-based metabolomics, as well as novel analytical tools including the Mendelian randomization (MR) approach, enabling genetic causal inference, may create new treatment opportunities for HT and related CVDs. MR analysis may constitute additional evidence for observational studies and facilitate selection of drug targets for clinical testing and has been already used to nominate potentially causal biomarkers for HT and CVDs such as circulating glycine, branched-chain amino acids, lipoprotein(a), insulin-like growth factor 1, or fibronectin 1. Using the MR framework, genetic proxies for targets of already known drugs, such as statins, PCSK9, and ACE inhibitors, may additionally be informative about potential side effects and eventually contribute to more personalized medicine. Finally, genetic causal inference may disentangle independent direct effects of correlated traits such as lipid classes or markers of inflammation on cardiovascular clinical outcomes such as atherosclerosis and HT. While several novel HT-targeting drugs are currently under clinical investigation (e.g. brain renin-angiotensin-aldosterone system inhibitors or endothelin-1 receptor antagonists), analysis of high-throughput proteomic and metabolomic data from well-powered studies may deliver novel druggable molecular targets for HT and associated CVDs.

Serum and Vascular Stiffness Biomarkers Associated with the Severity of Degenerative Aortic Valve Stenosis and Cardiovascular Outcomes.

Background: Although degenerative aortic valve stenosis (DAS) is the most prevalent growth-up congestive heart valve disease, still little known about relationships between DAS severity, vascular stiffness (VS), echocardiographic parameters, and serum biomarkers in patients undergoing transcatheter (TAVR) or surgical aortic valve replacement (SAVR). The objective of this study was to identify biomarkers associated with DAS severity, and those that are associated with cardiovascular death (CVD) and episodes of chronic heart failure (CHF) exacerbation. Methods: A total of 137 patients with initially moderate-to-severe DAS were prospectively evaluated for the relationship between DAS severity, baseline VS, and serum biomarkers (uPAR, GDF-15, Gal-3, IL-6Rα, ET-1, PCSK9, RANTES/CCL5, NT-proBNP, and hs-TnT), and were followed-up for 48 months. The prognostic significance of each variable for CVD and CHF risk was measured by hazard ratio of risk (HR), which was calculated by Cox's proportional hazard model. Results: DAS severity showed correlations with IL-6Rα (r = 0.306, p < 0.001), uPAR (r = 0.184, p = 0.032), and NT-proBNP (r = −0.389, p < 0.001). Levels of ET-1 and Gal-3 were strongly correlated with VS parameters (r = 0.674, p < 0.001; r = 0.724, p < 0.001). Out of 137 patients, 20 were referred to TAVR, 88 to SAVR, and 29 to OMT. In TAVR patients, the highest levels of ET-1, Gal-3, and VS were found as compared to other patients. The highest incidence of CVD was observed in patients who underwent TAVR (35%), compared to SAVR (8%) and OMT (10.3%) (p = 0.004). In a multivariate analysis, ET-1 occurred predictive of CVD risk (HR 25.1, p = 0.047), while Gal-3 > 11.5 ng/mL increased the risk of CHF exacerbation episodes requiring hospital admission by 12%. Conclusions: Our study indicated that ET-1 and Gal-3 levels may be associated with the outcomes in patients with DAS.

Breast cancer chemotherapy induces vascular dysfunction and hypertension through a NOX4-dependent mechanism.

Cardiovascular disease is the major cause of morbidity and mortality in breast cancer survivors. Chemotherapy contributes to this risk. We aimed to define the mechanisms of long-term vascular dysfunction caused by neoadjuvant chemotherapy (NACT) and identify novel therapeutic targets. We studied arteries from postmenopausal women who had undergone breast cancer treatment using docetaxel, doxorubicin, and cyclophosphamide (NACT) and from women with no history of such treatment matched for key clinical parameters. We explored mechanisms in WT and Nox4-/- mice and in human microvascular endothelial cells. Endothelium-dependent, NO-mediated vasodilatation was severely impaired in patients after NACT, while endothelium-independent responses remained normal. This was mimicked by a 24-hour exposure of arteries to NACT agents ex vivo. When applied individually, only docetaxel impaired endothelial function in human vessels. Mechanistic studies showed that NACT increased inhibitory eNOS phosphorylation of threonine 495 in a Rho-associated protein kinase-dependent (ROCK-dependent) manner and augmented vascular superoxide and hydrogen peroxide production and NADPH oxidase activity. Docetaxel increased expression of the NADPH oxidase NOX4 in endothelial and smooth muscle cells and NOX2 in the endothelium. A NOX4 increase in human arteries may be mediated epigenetically by diminished DNA methylation of the NOX4 promoter. Docetaxel induced endothelial dysfunction and hypertension in mice, and these were prevented in Nox4-/- mice and by pharmacological inhibition of Nox4 or Rock. Commonly used chemotherapeutic agents and, in particular, docetaxel alter vascular function by promoting the inhibitory phosphorylation of eNOS and enhancing ROS production by NADPH oxidases.

Silencing of Sphingosine kinase 1 Affects Maturation Pathways in Mouse Neonatal Cardiomyocytes.

Sphingosine kinase-1 (Sphk1) and its product, sphingosine-1-phosphate (S1P) are important regulators of cardiac growth and function. Numerous studies have reported that Sphk1/S1P signaling is essential for embryonic cardiac development and promotes pathological cardiac hypertrophy in adulthood. However, no studies have addressed the role of Sphk1 in postnatal cardiomyocyte (CM) development so far. The present study aimed to assess the molecular mechanism(s) by which Sphk1 silencing might influence CMs development and hypertrophy in vitro. Neonatal mouse CMs were transfected with siRNA against Sphk1 or negative control, and subsequently treated with 1 µM angiotensin II (AngII) or a control buffer for 24 h. The results of RNASeq analysis revealed that diminished expression of Sphk1 significantly accelerated neonatal CM maturation by inhibiting cell proliferation and inducing developmental pathways in the stress (AngII-induced) conditions. Importantly, similar effects were observed in the control conditions. Enhanced maturation of Sphk1-lacking CMs was further confirmed by the upregulation of the physiological hypertrophy-related signaling pathway involving Akt and downstream glycogen synthase kinase 3 beta (Gsk3ß) downregulation. In summary, we demonstrated that the Sphk1 silencing in neonatal mouse CMs facilitated their postnatal maturation in both physiological and stress conditions.

White Blood Cells and Blood Pressure: A Mendelian Randomization Study.

BACKGROUND: High blood pressure (BP) is a risk factor for cardiovascular morbidity and mortality. While BP is regulated by the function of kidney, vasculature, and sympathetic nervous system, recent experimental data suggest that immune cells may play a role in hypertension. METHODS: We studied the relationship between major white blood cell types and blood pressure in the UK Biobank population and used Mendelian randomization (MR) analyses using the ≈750 000 UK-Biobank/International Consortium of Blood Pressure-Genome-Wide Association Studies to examine which leukocyte populations may be causally linked to BP. RESULTS: A positive association between quintiles of lymphocyte, monocyte, and neutrophil counts, and increased systolic BP, diastolic BP, and pulse pressure was observed (eg, adjusted systolic BP mean±SE for 1st versus 5th quintile respectively: 140.13±0.08 versus 141.62±0.07 mm Hg for lymphocyte, 139.51±0.08 versus 141.84±0.07 mm Hg for monocyte, and 137.96±0.08 versus 142.71±0.07 mm Hg for neutrophil counts; all P<10-50). Using 121 single nucleotide polymorphisms in MR, implemented through the inverse-variance weighted approach, we identified a potential causal relationship of lymphocyte count with systolic BP and diastolic BP (causal estimates: 0.69 [95% CI, 0.19-1.20] and 0.56 [95% CI, 0.23-0.90] of mm Hg per 1 SD genetically elevated lymphocyte count, respectively), which was directionally concordant to the observational findings. These inverse-variance weighted estimates were consistent with other robust MR methods. The exclusion of rs3184504 SNP in the SH2B3 locus attenuated the magnitude of the signal in some of the MR analyses. MR in the reverse direction found evidence of positive effects of BP indices on counts of monocytes, neutrophils, and eosinophils but not lymphocytes or basophils. Subsequent MR testing of lymphocyte count in the context of genetic correlation with renal function or resting and postexercise heart rate demonstrated a positive association of lymphocyte count with urine albumin-to-creatinine ratio. CONCLUSIONS: Observational and genetic analyses demonstrate a concordant, positive and potentially causal relationship of lymphocyte count with systolic BP and diastolic BP.

miR-378a influences vascularization in skeletal muscles.

AIMS: MicroRNA-378a, highly expressed in skeletal muscles, was demonstrated to affect myoblasts differentiation and to promote tumour angiogenesis. We hypothesized that miR-378a could play a pro-angiogenic role in skeletal muscle and may be involved in regeneration after ischaemic injury in mice. METHODS AND RESULTS: Silencing of miR-378a in murine C2C12 myoblasts did not affect differentiation but impaired their secretory angiogenic potential towards endothelial cells. miR-378a knockout (miR-378a-/-) in mice resulted in a decreased number of CD31-positive blood vessels and arterioles in gastrocnemius muscle. In addition, diminished endothelial sprouting from miR-378a-/- aortic rings was shown. Interestingly, although fibroblast growth factor 1 (Fgf1) expression was decreased in miR-378a-/- muscles, this growth factor did not mediate the angiogenic effects exerted by miR-378a. In vivo, miR-378a knockout did not affect the revascularization of the ischaemic muscles in both normo- and hyperglycaemic mice subjected to femoral artery ligation (FAL). No difference in regenerating muscle fibres was detected between miR-378a-/- and miR-378+/+ mice. miR-378a expression temporarily declined in ischaemic skeletal muscles of miR-378+/+ mice already on Day 3 after FAL. At the same time, in the plasma, the level of miR-378a-3p was enhanced. Similar elevation of miR-378a-3p was reported in the plasma of patients with intermittent claudication in comparison to healthy donors. Local adeno-associated viral vectors-based miR-378a overexpression was enough to improve the revascularization of the ischaemic limb of wild-type mice on Day 7 after FAL, what was not reported after systemic delivery of vectors. In addition, the number of infiltrating CD45+ cells and macrophages (CD45+ CD11b+ F4/80+ Ly6G-) was higher in the ischaemic muscles of miR-378a-/- mice, suggesting an anti-inflammatory action of miR-378a. CONCLUSIONS: Data indicate miR-378a role in the pro-angiogenic effect of myoblasts and vascularization of skeletal muscle. After the ischaemic insult, the anti-angiogenic effect of miR-378a deficiency might be compensated by enhanced inflammation.

Cardiovascular Effects of Pharmacological Targeting of Sphingosine Kinase 1.

High blood pressure is a risk factor for cardiovascular diseases. Ang II (angiotensin II), a key pro-hypertensive hormone, mediates target organ consequences such as endothelial dysfunction and cardiac hypertrophy. S1P (sphingosine-1-phosphate), produced by Sphk1 (sphingosine kinase 1), plays a pivotal role in the pathogenesis of hypertension and downstream organ damage, as it controls vascular tone and regulates cardiac remodeling. Accordingly, we aimed to examine if pharmacological inhibition of Sphk1 using selective inhibitor PF543 can represent a useful vasoprotective and cardioprotective anti-hypertensive strategy in vivo. PF543 was administered intraperitoneally throughout a 14-day Ang II-infusion in C57BL6/J male mice. Pharmacological inhibition of Sphk1 improved endothelial function of arteries of hypertensive mice that could be mediated via decrease in eNOS (endothelial nitric oxide synthase) phosphorylation at T495. This effect was independent of blood pressure. Importantly, PF543 also reduced cardiac hypertrophy (heart to body weight ratio, 5.6±0.2 versus 6.4±0.1 versus 5.9±0.2 mg/g; P<0.05 for Sham, Ang II+placebo, and Ang II+PF543-treated mice, respectively). Mass spectrometry revealed that PF543 elevated cardiac sphingosine, that is, Sphk1 substrate, content in vivo. Mechanistically, RNA-Seq indicated a decreased expression of cardiac genes involved in actin/integrin organization, S1pr1 signaling, and tissue remodeling. Indeed, downregulation of Rock1 (Rho-associated coiled-coil containing protein kinase 1), Stat3 (signal transducer and activator of transcription 3), PKC (protein kinase C), and ERK1/2 (extracellular signal-regulated kinases 1/2) level/phosphorylation by PF543 was observed. In summary, pharmacological inhibition of Sphk1 partially protects against Ang II-induced cardiac hypertrophy and endothelial dysfunction. Therefore, it may represent a promising target for harnessing residual cardiovascular risk in hypertension.

Various roles of heme oxygenase-1 in response of bone marrow macrophages to RANKL and in the early stage of osteoclastogenesis.

Heme oxygenase-1 (HO-1; encoded by Hmox1), a downstream target of the Nrf2 transcription factor, has been postulated to be a negative regulator of osteoclasts (OCLs) differentiation. Here, we further explored such a hypothesis by examining HO-1 effects in different stages of osteoclastogenesis. We confirmed the inhibition of the expression of OCLs markers by Nrf2. In contrast, both the lack of the active Hmox1 gene or HO-1 silencing in OCLs precursor cells, bone marrow macrophages (BMMs), decreased their differentiation towards OCLs, as indicated by the analysis of OCLs markers such as TRAP. However, no effect of HO-1 deficiency was observed when HO-1 expression was silenced in BMMs or RAW264.7 macrophage cell line pre-stimulated with RANKL (considered as early-stage OCLs). Moreover, cobalt protoporphyrin IX (CoPPIX) or hemin, the known HO-1 inducers, inhibited OCLs markers both in RANKL-stimulated RAW264.7 cells and BMMs. Strikingly, a similar effect occurred in HO-1-/- cells, indicating HO-1-independent activity of CoPPIX and hemin. Interestingly, plasma of HO-1-/- mice contained higher TRAP levels, which suggests an increased number of bone-resorbing OCLs in the absence of HO-1 in vivo. In conclusion, our data indicate that HO-1 is involved in the response of bone marrow macrophages to RANKL and the induction of OCLs markers, but it is dispensable in early-stage OCLs. However, in vivo HO-1 appears to inhibit OCLs formation.