Shigetoyo Kogaki

Comprehensive genetic analysis of relevant four genes in 49 patients with Marfan syndrome or Marfan‐related phenotypes

In order to evaluate the contribution of FBN1, FBN2, TGFBR1, and TGFBR2 mutations to the Marfan syndrome (MFS) phenotype, the four genes were analyzed by direct sequencing in 49 patients with MFS or suspected MFS as a cohort study. A total of 27 FBN1 mutations (22 novel) in 27 patients (55%, 27/49), 1 novel TGFBR1 mutation in 1 (2%, 1/49), and 2 recurrent TGFBR2 mutations in 2 (4%, 2/49) were identified. No FBN2 mutation was found. Three patients with either TGFBR1 or TGFBR2 abnormality did not fulfill the Ghent criteria, but expressed some overlapping features of MFS and Loeys–Dietz syndrome (LDS). In the remaining 19 patients, either of the genes did not show any abnormalities. This study indicated that FBN1 mutations were predominant in MFS but TGFBRs defects may account for approximately 5–10% of patients with the syndrome.

Brain Natriuretic Peptide as a Hormonal Marker of Ventricular Diastolic Dysfunction in Children with Kawasaki Disease

Although an increased level of serum brain natriuretic peptide (BNP) has been reported in children in the acute phase of Kawasaki disease (KD), no precise relation was documented between the serum BNP level and left ventricular (LV) systolic function. We hypothesized that the increased BNP levels may be explained by diastolic abnormalities in those with KD. We prospectively studied 25 patients in the acute phase of KD. Patients with abnormal systolic function were excluded. Pediatric cardiologists making the assessment of LV diastolic function were blinded to the BNP levels. Doppler interrogation was applied to measure LV inflow velocities, which were transformed to z scores using control measurements obtained from 83 healthy subjects. In the patients, the BNP levels ranged from 2.0 to 450.0 pg/ml, with a mean of 54.0 ± 102.8 pg/ml. Six patients with abnormal velocities (> 2 SD in z score) showed significantly higher levels of BNP (152 ± 173 pg/ml) than those in the remaining patients (p < 0.01). The BNP levels correlated positively with diastolic atrial velocity in z score (r = 0.51, p < 0.05), and negatively with diastolic early velocity to atrial velocity ratio in z score (r = -0.75, p < 0.01). This study suggests that LV diastolic dysfunction may occur in some children in the acute phase of KD, causing an increased level of BNP.

Selectin on activated platelets enhances neutrophil endothelial adherence in myocardial reperfusion injury

OBJECTIVES The glycoprotein P-selectin is an adhesion molecule that is rapidly expressed on the surface of platelets and endothelium during the inflammatory process. P-selectin on endothelium has been reported to play an important role in reperfusion injury. However, little is known regarding P-selectin on platelets in contributing to the pathophysiology of myocardial reperfusion injury. In this study, we hypothesized that P-selectin on platelets may enhance neutrophil endothelial adherence and this may play a role in neutrophil-mediated reperfusion injury. METHODS Endothelial cells, cardiomyocytes, platelets and neutrophils were isolated from adult rats. Endothelial cells and cardiomyocytes were cultivated in a co-culture system. After exposure to hypoxia and reoxygenation, neutrophil adherence and migration were examined. RESULTS After exposure to 6 h of hypoxia, endothelial cells co-incubated with platelets showed significantly greater neutrophil adherence (63.1 +/- 4.0%) and migration (78.2 +/- 6.7%) than endothelial cells alone (adhesion: 44.2 +/- 2.8%, migration: 57.9 +/- 4.9%). These increases were significantly inhibited (adhesion: 42.1 +/- 3.5%, migration: 65.5 +/- 3.8%) by an anti-P-selectin monoclonal antibody. Moreover, the superoxide-anion production was significantly elevated when activated platelets were added to neutrophils. This enhanced production was also inhibited by anti-P-selectin antibody. CONCLUSION The presence of activated platelets enhanced neutrophil adhesion and migration process after hypoxia reoxygenation. This process may occur following platelet-neutrophil interactions via P-selectin and subsequent neutrophil activation.

A novel mutation in the PTPN11 gene in a patient with Noonan syndrome and rapidly progressive hypertrophic cardiomyopathy

A male infant with clinical features of Noonan syndrome and rapidly progressive hypertrophic cardiomyopathy is reported. He manifested severe heart failure and failure to thrive. Administration of propranolol and cibenzoline improved ventricular outflow tract obstruction, leading to catch-up growth. Genetic analysis of the patient revealed a novel missense mutation in the PTPN11 gene. Conclusion:This is the first description of a patient with a Gln510Glu mutation in the protein-tyrosine phosphatase, non-receptor type 11 gene. This specific mutation may be associated with a rapidly progressive hypertrophic cardiomyopathy.

Overexpression of endothelin-1 and endothelin receptors in the pulmonary arteries of failed Fontan patients

BACKGROUND Endothelin-1 (ET-1), a potent vasoconstrictor, is considered to be implicated in failing Fontan circulation, however the expressions of ET-1 and endothelin receptor type A (ET(A)R) and type B (ET(B)R) in the pulmonary arteries of failed Fontan patients were not elucidated. METHODS Immunohistochemistry and quantitative real-time PCR were used to analyse the expression levels of ET-1 and its receptors in the pulmonary arteries of the autopsy lung tissues of the patients who died after the Fontan procedure (n=10). We divided these patients into 3 groups, failed Fontan (n=4), heart failure (n=3) and non-failed Fontan (n=3), and then compared those to the age-matched normal controls (n=4). RESULTS The intra-acinar pulmonary arteries of failed Fontan patients showed significant medial hypertrophy. Computational optical density analyses of the immunostaining revealed that the expressions of ET-1, ET(A)R, and ET(B)R in the intra-acinar pulmonary arteries were significantly increased in the failed Fontan patients (P<0.05 vs. normal controls), however no significant difference was observed between the non-failed Fontan patients and the normal controls. Quantitative real-time PCR analyses confirmed that the mRNA expressions of ET-1, ET(A)R, and ET(B)R were significantly increased in the failed Fontan patients (P<0.05 vs. normal controls). CONCLUSION The overexpression of ET-1 and its receptors in the pulmonary arteries can cause pulmonary vasoconstriction and vascular remodelling, leading to failed Fontan circulation. This study suggests a histopathological rationale for the potential benefits of endothelin receptor antagonists in patients with failing Fontan circulation.

LEOPARD-type SHP2 mutant Gln510Glu attenuates cardiomyocyte differentiation and promotes cardiac hypertrophy via dysregulation of Akt/GSK-3β/β-catenin signaling

LEOPARD syndrome (LS) is an autosomal dominant inherited multisystemic disorder. Most cases involve mutations in the PTPN11 gene, which encodes the protein tyrosine phosphatase Src homology 2-containing protein phosphatase 2 (SHP2). LS frequently causes severe hypertrophic cardiomyopathy (HCM), even from the fetal period. However, the molecular pathogenesis has not been clearly elucidated. Here, we analyzed the roles of the LS-type SHP2 mutant Gln510Glu (Q510E), which showed the most severe type of HCM in LS, in cardiomyocyte differentiation, and in morphological changes. We generated mutant P19CL6 cell lines, the most convenient cardiomyocyte differentiation model, which continuously expressed SHP2-Q510E, SHP2-D61N (Noonan-type mutant), wild-type SHP2, and green fluorescent protein (native SHP2 expression only). SHP2-Q510E mutant P19CL6 cells showed significant attenuation of myofibrillogenesis, with increased proliferative activity. Mature cardiomyocytes from the SHP2-Q510E mutant were significantly larger than those of controls and the other mutants. However, expression of cardiac-specific transcriptional factors (Gata4, Tbx5, and Nkx2.5) did not differ significantly between the LS-type SHP2-Q510E mutants and the other mutants and controls. Our results indicate that SHP2-Q510E mutants can differentiate into cardiac progenitors but are inhibited from undergoing terminal differentiation into mature cardiomyocytes. In contrast, Akt and glycogen synthase kinase (GSK)-3β phosphorylation were upregulated, and nuclear β-catenin at the late stage of differentiation was highly accumulated in SHP2-Q510E mutant P19CL6 cells. Supplementation with the phosphoinositide 3-kinase/Akt inhibitor LY-294002 during the late stage of differentiation was found to partially restore myofibrillogenesis while suppressing the increase in size of individual mature cardiomyocytes derived from the SHP2-Q510E mutants. Our findings suggest that dysregulation of the Akt/GSK-3β/β-catenin pathway can contribute to the pathogenesis of HCM in LS patients, not only through hypertrophic changes in individual cardiac cells but also via the expansion of cardiac progenitors.

Hypoxia induces alteration of bone morphogenetic protein receptor signaling in pulmonary artery endothelial cell.

Reduced expression of bone morphogenetic protein receptors (BMPR) has been implicated in the pathogenesis of pulmonary hypertension (PH), but changes in the intracellular signaling pathway of BMPR have not been fully understood. We hypothesized that BMPR signaling in pulmonary endothelial cells is altered during the development of PH, such as hypoxia-induced PH. We examined the expression of BMPR, BMP-regulated Smads and Id-1 in lung tissues of Sprague-Dawley rats exposed to 2 wk of hypoxia and in isolated lung vascular endothelial cells exposed to hypoxia. BMPRII was predominantly expressed in the endothelial cells (EC) of pulmonary vasculature. In hypoxic rats, reduced expression of BMPRII was observed in the EC of resistance pulmonary arteries. The expression of phosphorylated-Smad1/5/8 and Id-1 in EC was also reduced, whereas the expression of Smad1 as well as activin receptor-like kinase 1 (ALK1) was up-regulated during the development of PH. In in vitro exposure to hypoxia, the expression of mRNA transcripts for BMPRII, Smad8, and Id-1 in EC was reduced, whereas mRNA of Smad1 was not diminished. Our results suggest that hypoxia induces alteration of intracellular BMPR signaling in the EC of resistance pulmonary artery, which is involved in the pathogenesis of PH.

14-3-3ε Gene variants in a Japanese patient with left ventricular noncompaction and hypoplasia of the corpus callosum

BACKGROUND Left ventricular noncompaction (LVNC) is a cardiomyopathy characterized by a prominent trabecular meshwork and deep intertrabecular recesses, and is thought to be due to an arrest of normal endomyocardial morphogenesis. However, the genes contributing to this process remain poorly understood. 14-3-3ε, encoded by YWHAE, is an adapter protein belonging to the 14-3-3 protein family which plays important roles in neuronal development and is involved in Miller-Dieker syndrome. We recently showed that mice lacking this gene develop LVNC. Therefore, we hypothesized that variants in YWHAE may contribute to the pathophysiology of LVNC in humans. METHODS AND RESULTS In 77 Japanese patients with LVNC, including the probands of 29 families, mutation analysis of YWHAE by direct DNA sequencing identified 7 novel variants. One of them, c.-458G>T, in the YWHAE promoter, was identified in a familial patient with LVNC and hypoplasia of the corpus callosum. The -458G>T variant is located within a regulatory CCAAT/enhancer binding protein (C/EBP) response element of the YWHAE promoter, and it reduced promoter activity by approximately 50%. Increased binding of an inhibitory C/EBPβ isoform was implicated in decreasing YWHAE promoter activity. Interestingly, we had previously shown that C/EBPβ is a key regulator of YWHAE. CONCLUSIONS These data suggest that the -458G>T YWHAE variant contributes to the abnormal myocardial morphogenesis characteristic of LVNC as well as abnormal brain development, and implicate YWHAE as a novel candidate gene in pediatric cardiomyopathies.

Successful stenting for renal artery stenosis in a patient with Alagille syndrome.

A 12-year-old girl with Alagille syndrome manifested severe hypertension caused by renal artery stenosis in a solitary functioning kidney. Percutaneous transluminal angioplasty (PTA) and stenting was performed, but the hypertension persisted. On the next day, acute renal failure occurred with the administration of angiotensin-converting enzyme inhibitor, and migration of the stent was confirmed by angiography. Thus, a second stent was placed with success. Since then, the hypertension has been controlled with anti-hypertensive medication, and the renal function has recovered to normal range.

Generation of Induced Pluripotent Stem Cells From Patients With Duchenne Muscular Dystrophy and Their Induction to Cardiomyocytes.

Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene which encodes dystrophin protein. Dystrophin defect affects cardiac muscle as well as skeletal muscle. Cardiac dysfunction is observed in all patients with DMD over 18 years of age, but there is no curative treatment for DMD cardiomyopathy. To establish novel experimental platforms which reproduce the cardiac phenotype of DMD patients, here we established iPS cell lines from T lymphocytes donated from two DMD patients, with a protocol using Sendai virus vectors. We successfully conducted the differentiation of the DMD patient-specific iPS cells into beating cardiomyocytes. DMD patient-specific iPS cells and iPS cell-derived cardiomyocytes would be a useful in vitro experimental system with which to investigate DMD cardiomyopathy.