Serum Biomarkers of Endothelial Dysfunction in Fabry Associated Cardiomyopathy

Background: Fabry disease (FD) is characterized by early development of vasculopathy and endothelial dysfunction. However, it is unclear whether these findings also play a pivotal role in cardiac manifestation. As Fabry cardiomyopathy (FC) is the leading cause of death in FD, we aimed to gather a better insight in pathological mechanisms of the disease.Methods: Serum samples were obtained from 17 healthy controls, 15 FD patients with and 7 without FC. FC was defined by LV wall thickening of >12 mm in cardiac magnetic resonance imaging and serum level of proBNP, high sensitive Troponin T (hsT), and globotriaosylsphingosine (lyso-GB3) were obtained. A multiplex ELISA-Assay for 23 different angiogenesis markers was performed in pooled samples. Markers showing significant differences among groups were further analyzed in single samples using specific Elisa antibody assays. L-homoarginine (hArg), L-arginine, asymmetric (ADMA), and symmetric Dimethylarginine (SDMA) were quantified by liquid chromatography—mass spectrometry.Results: Angiostatin and matrix metalloproteinase 9 (MMP-9) were elevated in FD patients compared to controls independently of the presence of FC (angiostatin: 98 ± 25 vs. 75 ± 15 ng/mL; p = 0.001; MMP-9: 8.0 ± 3.4 vs. 5.0 ± 2.4 μg/mL; p = 0.002). SDMA concentrations were highest in patients with FC (0.90 ± 0.64 μmol/l) compared to patients without (0.57 ± 0.10 μmol/l; p = 0.027) and vs. controls (0.58 ± 0.12 μmol/l; p = 0.006) and was positively correlated with indexed LV-mass (r = 0.61; p = 0.003), hsT (r = 0.56, p = 0.008), and lyso-Gb3 (r = 0.53, p = 0.013). Accordingly, the ratio of L-homoarginine to SDMA (hArg/SDMA) was lowest in patients with FC (2.63 ± 1.78) compared to controls (4.16 ± 1.44; p = 0.005). For L-arginine, hArg and ADMA no significant differences among groups could be detected, although a trend toward higher ADMA and lower hArg levels could be observed in the FC group. Furthermore, a significant relationship between kidney and cardiac function could be revealed (p = 0.045).Conclusion: Elevated MMP-9 and angiostatin levels suggest an increased extracellular matrix turnover in FD patients. Furthermore, endothelial dysfunction may also be involved in FC, as SDMA and hArg/SDMA are altered in these patients

Dietary Supplementation with Homoarginine Preserves Cardiac Function in a Murine Model of Post-Myocardial Infarction Heart Failure

Low plasma homoarginine (HA) is an emerging biomarker for cardiovascular disease and an independent predictor of mortality in patients with heart failure. Plasma levels appear to reflect cardiac dysfunction, positively correlating with ejection fraction and inversely with circulating brain natriuretic peptide. However, whether this outcome is a bystander or cause-and-effect has yet to be established. Within the context of stroke, a direct causal relationship has been inferred because normal mice pretreated with 14 mg/L HA had a smaller stroke size. In the present study, we show for the first time that dietary supplementation with HA improves cardiac function in the setting of chronic heart failure, suggesting a novel preventive strategy and inferring that low HA levels may be inherently detrimental because of a loss of this effect

Association of Asymmetric Dimethylarginine and Diastolic Dysfunction in Patients with Hypertrophic Cardiomyopathy

Despite genetic heterogeneity, early manifestation of diastolic dysfunction (DD) is common in hypertrophic cardiomyopathy (HCM). Nitric oxide (NO) may contribute to myocardial relaxation. NO synthases (NOS) use l-arginine (Arg) as a substrate, as asymmetric dimethylarginine (ADMA) is a direct endogenous inhibitor of NOS. This study aimed to analyze the association of Arg and its derivates, i.e., l-homoarginine (hArg), ADMA and symmetric dimethylarginine (SDMA), with DD in HCM patients. In 215 HCM patients (mean age 54 ± 15 years, 58% male) transmitral and mitral annulus velocities were echocardiographically analyzed. Plasma concentrations of Arg derivatives were measured by liquid chromatography tandem-mass spectrometry. In 143 (70%) patients suffering from DD, ADMA showed the strongest association with DD (0.66 ± 0.16, 0.72 ± 0.24, and 0.76 ± 0.26 µmol/L, p < 0.01 for trend). In linear regression analyses, positive association per standard deviation increase of ADMA was found with E-wave (beta coefficient (95% confidence interval): 4.72 (0.43–9.01); p < 0.05) and mean E/E’ (1.76 (0.73–2.79) p < 0.001). Associations were adjusted for age, sex, body mass index (BMI), diabetes mellitus, coronary artery disease, and arterial hypertension. Elevated ADMA is associated with the severity of DD in HCM. Higher ADMA level might lead to decreased NO production and thus an impaired myocardial relaxation pattern

Homoarginine supplementation improves blood glucose in diet-induced obese mice

l-Homoarginine (hArg) is an endogenous amino acid which has emerged as a novel biomarker for stroke and cardiovascular disease. Low circulating hArg levels are associated with increased mortality and vascular events, whereas recent data have revealed positive correlations between circulating hArg and metabolic vascular risk factors like obesity or blood glucose levels. However, it is unclear whether hArg levels are causally linked to metabolic parameters. Therefore, the aim of our study was to investigate whether hArg directly influences body weight, blood glucose, glucose tolerance or insulin sensitivity. Here, we show that hArg supplementation (14 and 28 mg/mL orally per drinking water) ameliorates blood glucose levels in mice on high-fat diet (HFD) by a reduction of 7.3 +/- A 3.7 or 13.4 +/- A 3.8 %, respectively. Fasting insulin concentrations were slightly, yet significantly affected (63.8 +/- A 11.3 or 162.1 +/- A 39.5 % of control animals, respectively), whereas body weight and glucose tolerance were unaltered. The substantial augmentation of hArg plasma concentrations in supplemented animals (327.5 +/- A 40.4 or 627.5 +/- A 60.3 % of control animals, respectively) diminished profoundly after the animals became obese (129.9 +/- A 16.6 % in control animals after HFD vs. 140.1 +/- A 8.5 or 206.3 +/- A 13.6 %, respectively). This hArg-lowering effect may contribute to the discrepancy between the inverse correlation of plasma hArg levels with stroke and cardiovascular outcome, on the one hand, and the direct correlation with cardiovascular risk factors like obesity and blood glucose, on the other hand, that has been observed in human studies. Our results suggest that the glucose-lowering effects of hArg may reflect a compensatory mechanism of blood glucose reduction by hArg upregulation in obese individuals, without directly influencing body weight or glucose tolerance

Muscle phenotype of AGAT- and GAMT-deficient mice after simvastatin exposure

Statin-induced myopathy affects more than 10 million people worldwide. But discontinuation of statin treatment increases mortality and cardiovascular events. Recently, l-arginine:glycine amidinotransferase (AGAT) gene was associated with statin-induced myopathy in two populations, but the causal link is still unclear. AGAT is responsible for the synthesis of l-homoarginine (hArg) and guanidinoacetate (GAA). GAA is further methylated to creatine (Cr) by guanidinoacetate methyltransferase (GAMT). In cerebrovascular patients treated with statin, lower hArg and GAA plasma concentrations were found than in non-statin patients, indicating suppressed AGAT expression and/or activity (n = 272, P = 0.033 and P = 0.039, respectively). This observation suggests that statin-induced myopathy may be associated with AGAT expression and/or activity in muscle cells. To address this, we studied simvastatin-induced myopathy in AGAT- and GAMT-deficient mice. We found that simvastatin induced muscle damage and reduced AGAT expression in wildtype mice (myocyte diameter: 34.1 +/- 1.3 mu m vs 21.5 +/- 1.3 mu m, P = 0.026; AGAT expression: 1.0 +/- 0.3 vs 0.48 +/- 0.05, P = 0.017). Increasing AGAT expression levels of transgenic mouse models resulted in rising plasma levels of hArg and GAA (P < 0.01 and P < 0.001, respectively). Simvastatin-induced motor impairment was exacerbated in AGAT-deficient mice compared with AGAT-overexpressing GAMT(-/-) mice and therefore revealed an effect independent of Cr. But Cr supplementation itself improved muscle strength independent of AGAT expression (normalized grip strength: 55.8 +/- 2.9% vs 72.5% +/- 3.0%, P < 0.01). Homoarginine supplementation did not affect statin-induced myopathy in AGAT-deficient mice. Our results from clinical and animal studies suggest that AGAT expression/activity and its product Cr influence statin-induced myopathy independent of each other. The interplay between simvastatin treatment, AGAT expression and activity, and Cr seems to be complex. Further clinical pharmacological studies are needed to elucidate the underlying mechanism(s) and to evaluate whether supplementation with Cr, or possibly GAA, in patients under statin medication may reduce the risk of muscular side effects

Low homoarginine levels in the prognosis of patients with acute chest pain

Background The endogenous amino acid homoarginine predicts mortality in cerebro‐ and cardiovascular disease. The objective was to explore whether homoarginine is associated with atrial fibrillation (AF) and outcome in patients with acute chest pain. Methods and Results One thousand six hundred forty‐nine patients with acute chest pain were consecutively enrolled in this study, of whom 589 were diagnosed acute coronary syndrome (ACS). On admission, plasma concentrations of homoarginine as well as brain natriuretic peptide (BNP), and high‐sensitivity assayed troponin I (hsTnI) were determined along with electrocardiography (ECG) variables. During a median follow‐up of 183 days, 60 major adverse cardiovascular events (MACEs; 3.8%), including all‐cause death, myocardial infarction, or stroke, were registered in the overall study population and 43 MACEs (7.5%) in the ACS subgroup. Adjusted multivariable Cox regression analyses revealed that an increase of 1 SD of plasma log‐transformed homoarginine (0.37) was associated with a hazard reduction of 26% (hazard ratio [HR], 0.74; 95% CI, 0.57–0.96) for incident MACE and likewise of 35% (HR, 0.65; 95% CI, 0.49–0.88) in ACS patients. In Kaplan–Meier survival curves, homoarginine was predictive for patients with high‐sensitivity assayed troponin I (hsTnI) above 27 ng/L (P<0.05). Last, homoarginine was inversely associated with QTc duration (P<0.001) and prevalent AF (OR, 0.83; 95% CI, 0.71–0.95). Conclusion Low plasma homoarginine was identified as a risk marker for incident MACEs in patients with acute chest pain, in particular, in those with elevated hsTnI. Impaired homoarginine was associated with prevalent AF. Further studies are needed to investigate the link to AF and evaluate homoarginine as a therapeutic option for these patients

Health-Related Quality of Life in Spinal Muscular Atrophy Patients and Their Caregivers—A Prospective, Cross-Sectional, Multi-Center Analysis

Spinal muscular atrophy (SMA) is a disabling disease that affects not only the patient’s health-related quality of life (HRQoL), but also causes a high caregiver burden (CGB). The aim of this study was to evaluate HRQoL, CGB, and their predictors in SMA. In two prospective, cross-sectional, and multi-center studies, SMA patients (n = 39) and SMA patient/caregiver couples (n = 49) filled in the EuroQoL Five Dimension Five Level Scale (EQ-5D-5L) and the Short Form Health Survey 36 (SF-36). Caregivers (CGs) additionally answered the Zarit Burden Interview (ZBI) and the Hospital Anxiety and Depression Scale (HADS). Patients were clustered into two groups with either low or high HRQoL (EQ-5D-5L index value 0.679). The latter group was mostly composed of ambulatory type III patients with higher motor/functional scores. More severely affected patients reported low physical functioning but good mental health and vitality. The CGB (mean ZBI = 22/88) correlated negatively with patients’ motor/functional scores and age. Higher CGB was associated with a lower HRQoL, higher depression and anxiety, and more health impairments of the CGs. We conclude that patient and CG well-being levels interact closely, which highlights the need to consider the health of both parties while evaluating novel treatments