Genetic Testing Enables the Diagnosis of Familial Hypercholesterolemia Underdiagnosed by Clinical Criteria: Analysis of Japanese Early-Onset Coronary Artery Disease Patients.

Definitive diagnosis of familial hypercholesterolemia (FH) is paramount for the risk management of patients and their relatives. The present study aimed to investigate the frequency of gene variants contributing to low-density lipoprotein cholesterol (LDL-C) metabolism and their clinical relevance in patients with early-onset coronary artery disease (EOCAD). Among 63 consecutive patients with EOCAD (men <55 years or women <65 years) who underwent percutaneous coronary intervention (PCI) from 2013 to 2019 at Keio University Hospital, 52 consented to participate in this retrospective study. Targeted sequencing of LDLR, PCSK9, APOB, and LDLRAP1 was performed. Of the 52 patients enrolled (42 men; mean age: 50 ± 6 years), one (LDLR, c.1221_1222delCGinsT) harbored a pathogenic mutation, and one (APOB, c.10591A>G) harbored variants of uncertain significance. Both the patients harboring the variants were male, showing no history of diabetes mellitus or chronic kidney disease, no family history of EOCAD, and no physical findings of FH (i.e., tendon xanthomas or Achilles tendon thickening). Patients harboring the LDLR variant had three-vessel disease, were on a statin prescription at baseline, and had stable LDL-C levels; however, the case showed a poor response to the intensification of medication after PCI. Approximately 3.8% of patients with EOCAD harbored variants of gene related to LDL-C metabolism; there were no notable indicators in the patients' background or clinical course to diagnose FH. Given the difficulty in diagnosing FH based on clinical manifestations and family history, genetic testing could enable the identification of hidden risk factors and provide early warnings to their relatives.

The complement C3-complement factor D-C3a receptor signalling axis regulates cardiac remodelling in right ventricular failure.

Failure of the right ventricle plays a critical role in any type of heart failure. However, the mechanism remains unclear, and there is no specific therapy. Here, we show that the right ventricle predominantly expresses alternative complement pathway-related genes, including Cfd and C3aR1. Complement 3 (C3)-knockout attenuates right ventricular dysfunction and fibrosis in a mouse model of right ventricular failure. C3a is produced from C3 by the C3 convertase complex, which includes the essential component complement factor D (Cfd). Cfd-knockout mice also show attenuation of right ventricular failure. Moreover, the plasma concentration of CFD correlates with the severity of right ventricular failure in patients with chronic right ventricular failure. A C3a receptor (C3aR) antagonist dramatically improves right ventricular dysfunction in mice. In summary, we demonstrate the crucial role of the C3-Cfd-C3aR axis in right ventricular failure and highlight potential therapeutic targets for right ventricular failure.

TET2 Variants in Japanese Patients With Pulmonary Arterial Hypertension.

Recent studies have illuminated the importance of tet-methylcytosine-dioxygenase-2 (TET2) in pulmonary arterial hypertension (PAH). We aimed to clarify the frequency of TET2 variants in Japanese PAH patients. Among whole-exome sequencing of 145 Japanese patients with idiopathic or heritable PAH, 3 patients (2.1%) had a germline heterozygous missense variant in TET2 (c.3116C > T, p.Ser1039Leu). The allele frequency is 0.15% in the gnomAD database, and 0.2% among 3554 in the general Japanese population. These 3 patients needed combination therapy including continuous prostacyclin infusion. Our study identified a novel TET2 variant, and TET2 may have effects on the onset and/or disease progression of PAH.

Des études récentes ont mis en lumière l'importance de TET méthylcytosine dioxygénase 2 (TET2) dans l'hypertension artérielle pulmonaire (HTAP). Nous avons cherché à préciser la fréquence des mutations du gène TET2 chez des patients japonais atteints d'HTAP. Lors du séquençage de l'exome entier de 145 patients japonais présentant une HTAP idiopathique ou héréditaire, une mutation germinale hétérozygote faux-sens du TET2 (c.3116C > T, p.Ser1039Leu) a été détectée chez trois patients (2,1 %). La fréquence allélique est de 0,15 % dans la base de données gnomAD et de 0,2 % parmi 3 554 personnes au sein de la population japonaise en général. Les trois patients ont dû suivre un traitement d'association faisant notamment appel à la prostacycline administrée en perfusion continue. Notre étude a permis de découvrir une nouvelle mutation du gène TET2, et le TET2 peut avoir des effets sur l'apparition et/ou la progression de l'HTAP.

RNF213-Associated Vascular Disease: A Concept Unifying Various Vasculopathies.

The ring finger protein 213 gene (RNF213) encodes a 590 kDa protein that is thought to be involved in angiogenesis. This gene was first recognized as a vasculopathy-susceptibility locus through genome-wide association studies undertaken in a Japanese population, demonstrating that heterozygotes for RNF213 p.Arg4810Lys (c.14429G>A, rs112735431) had a greatly increased risk of moyamoya disease. The association of RNF213 p.Arg4810Lys as a susceptibility variant of moyamoya disease was reproduced in Korean and Chinese individuals and, later, in Caucasians. Variants of the RNF213 gene have been linked to a number of vascular diseases such as moyamoya disease, intracranial major artery stenosis, pulmonary arterial hypertension, and peripheral pulmonary artery stenosis, and have also been associated with co-occurrent diseases and vascular disease in different organs. Based on the findings that we have reported to date, our paper proposes a new concept of "RNF213-associated vascular disease" to unify these conditions with the aim of capturing patients with multiple diseases but with a common genetic background. This concept will be highly desirable for clarifying all of the diseases in the RNF213-associated vascular disease category by means of global epidemiological investigations because of the possibility of such diseases appearing asymptomatically in some patients.

Qualitative and Quantitative Effects of Fatty Acids Involved in Heart Diseases.

Fatty acids (FAs) have structural and functional diversity. FAs in the heart are closely associated with cardiac function, and their qualitative or quantitative abnormalities lead to the onset and progression of cardiac disease. FAs are important as an energy substrate for the heart, but when in excess, they exhibit cardio-lipotoxicity that causes cardiac dysfunction or heart failure with preserved ejection fraction. FAs also play a role as part of phospholipids that compose cell membranes, and the changes in mitochondrial phospholipid cardiolipin and the FA composition of plasma membrane phospholipids affect cardiomyocyte survival. In addition, FA metabolites exert a wide variety of bioactivities in the heart as lipid mediators. Recent advances in measurement using mass spectrometry have identified trace amounts of n-3 polyunsaturated fatty acids (PUFAs)-derived bioactive metabolites associated with heart disease. n-3 PUFAs have a variety of cardioprotective effects and have been shown in clinical trials to be effective in cardiovascular diseases, including heart failure. This review outlines the contributions of FAs to cardiac function and pathogenesis of heart diseases from the perspective of three major roles and proposes therapeutic applications and new medical perspectives of FAs represented by n-3 PUFAs.

Impact of additional selexipag on prostacyclin infusion analogs in patients with pulmonary arterial hypertension.

The effective therapy for pulmonary arterial hypertension (PAH) with inadequate clinical response is scarce except for lung transplantation when prostacyclin infusion is ineffective. The purpose of this study is to investigate the efficacy and safety of selexipag in addition to the infusion of prostacyclin. Nine patients [median 38 (36-49) years of age; 78% female] with PAH whose clinical response was inadequate despite the use of prostacyclin infusion analogs, were evaluated. Addition of selexipag significantly improved hemodynamics and no serious adverse events were observed. Selexipag with prostacyclin infusion analogs can be an effective therapeutic strategy for the PAH patients with inadequate clinical response.

Pharmacokinetics of hydrogen after ingesting a hydrogen-rich solution: A study in pigs.

Drinking hydrogen (H2)-rich water is a common way to consume H2. Although many studies have shown efficacy of drinking H2-rich water in neuropsychiatric and endocrine metabolic disorders, their authenticity has been questioned because none examined the associated pharmacokinetics of H2. Therefore, we performed the first study to investigate the pharmacokinetics of H2 in pigs given an H2-rich glucose solution with the aim to extrapolate the findings to humans. We inserted blood collection catheters into the jejunal and portal veins, suprahepatic inferior vena cava, and carotid artery of 4 female pigs aged 8 weeks. Then, within 2 min we infused 500 ml of either H2-rich or H2-free glucose solution into the jejunum via a percutaneous gastrostomy tube and measured changes in H2 concentration in venous and arterial blood over 120 min. After infusion of the H2-rich glucose solution, H2 concentration in the portal vein peaked at 0.05 mg/L and remained at more than 0.016 mg/L (H2 saturation level, 1%) after 1 h; it also increased after infusion of H2-free glucose solution but remained below 0.001 mg/L (H2 saturation level, 0.06%). We assume that H2 was subsequently metabolized in the liver or eliminated via the lungs because it was not detected in the carotid artery. In conclusion, drinking highly concentrated H2-rich solution within a short time is a good way to increase H2 concentration in portal blood and supply H2 to the liver.

Triple oral combination therapy with macitentan, riociguat, and selexipag for pulmonary arterial hypertension.

BACKGROUND: The evidence regarding triple oral combination therapy for patients with pulmonary arterial hypertension (PAH) is scarce. This study was performed to investigate the effectiveness and safety of triple oral combination therapy with macitentan, riociguat, and selexipag. METHODS: Among consecutive patients with PAH who were referred to our hospital from 2009 to 2020, those who underwent triple oral combination therapy using macitentan, riociguat, and selexipag were retrospectively analyzed. Hemodynamic and echocardiographic assessments and Kaplan-Meier analyses of all-cause death and initiation of prostacyclin infusion were conducted. RESULTS: Twenty-six patients underwent this combination therapy. These patients were predominantly female (73.1%) with a median age of 38 years at baseline and nine patients were taking some PAH medications at baseline. The median time from initiation of the first PAH drug to the third PAH drug in treatment naïve patients was 24 days (interquartile range, 12-47 days). Four patients (15.0%) discontinued taking any of the three vasodilators because of adverse events, and 17 patients (65.4%) reached the maximum dose of all three drugs. The mean pulmonary arterial pressure, pulmonary vascular resistance, and cardiac output improved by 29%, 65%, and 82%, respectively (median observation period: 441 days) and similar improvements were observed in treatment-naïve patients at baseline. The survival rate and prostacyclin infusion-free rate since administration of all three vasodilators was 93.3% and 74.6% at 3 years, respectively. When patients were divided by risk stratification, the prostacyclin-free rate at 3 years was 92.9% in low-/intermediate-risk patients and 55.0% in high-risk patients. CONCLUSION: Triple oral combination therapy with macitentan, riociguat, and selexipag sufficiently improved clinical parameters and was well tolerated in patients with PAH. This combination could be a particularly promising strategy in patients with low/intermediate risk and possibly even in half of patients with high risk. Further studies are needed to validate these findings.The reviews of this paper are available via the supplemental material section.

TNFRSF13B c.226G>A (p.Gly76Ser) as a Novel Causative Mutation for Pulmonary Arterial Hypertension.

Background Recently, some studies reported the pulmonary artery hypertension (PAH)-associated genes. However, a majority of patients with familial or sporadic PAH lack variants in the known pathogenic genes. In this study, we investigated the new causative gene variants associated with PAH. Methods and Results Whole-exome sequencing in 242 Japanese patients with familial or sporadic PAH identified a heterozygous substitution change involving c.226G>A (p.Gly76Ser) in tumor necrotic factor receptor superfamily 13B gene (TNFRSF13B) in 6 (2.5%) patients. TNFRSF13B controls the differentiation of B cell and secretion of inflammatory cytokines and may be involved in vascular inflammation. In silico structural analysis simulation demonstrated the structural instability of the N-terminal region of the protein synthesized from TNFRSF13B p.Gly76Ser variant. These suggest that the TNFRSF13B p.Gly76Ser variant may be involved in the development of PAH via aberrant inflammation in pulmonary vessels. Conclusions TNFRSF13B p.Gly76Ser variant is a candidate of novel causative gene variant for PAH.

Pharmacokinetics of a single inhalation of hydrogen gas in pigs.

The benefits of inhaling hydrogen gas (H2) have been widely reported but its pharmacokinetics have not yet been sufficiently analyzed. We developed a new experimental system in pigs to closely evaluate the process by which H2 is absorbed in the lungs, enters the bloodstream, and is distributed, metabolized, and excreted. We inserted and secured catheters into the carotid artery (CA), portal vein (PV), and supra-hepatic inferior vena cava (IVC) to allow repeated blood sampling and performed bilateral thoracotomy to collapse the lungs. Then, using a hydrogen-absorbing alloy canister, we filled the lungs to the maximum inspiratory level with 100% H2. The pig was maintained for 30 seconds without resuming breathing, as if they were holding their breath. We collected blood from the three intravascular catheters after 0, 3, 10, 30, and 60 minutes and measured H2 concentration by gas chromatography. H2 concentration in the CA peaked immediately after breath holding; 3 min later, it dropped to 1/40 of the peak value. Peak H2 concentrations in the PV and IVC were 40% and 14% of that in the CA, respectively. However, H2 concentration decay in the PV and IVC (half-life: 310 s and 350 s, respectively) was slower than in the CA (half-life: 92 s). At 10 min, H2 concentration was significantly higher in venous blood than in arterial blood. At 60 min, H2 was detected in the portal blood at a concentration of 6.9-53 nL/mL higher than at steady state, and in the SVC 14-29 nL/mL higher than at steady state. In contrast, H2 concentration in the CA decreased to steady state levels. This is the first report showing that inhaled H2 is transported to the whole body by advection diffusion and metabolized dynamically.