Emiko Ogawa

Endothelial Nitric Oxide Synthase Gene Is Positively Associated With Essential Hypertension

Essential hypertension has a genetic basis. Accumulating evidence, including findings of elevation of arterial blood pressure in mice lacking the endothelial nitric oxide synthase (eNOS) gene, strongly suggests that alteration in NO metabolism is implicated in hypertension. There are, however, no reports indicating that polymorphism in the eNOS gene is associated with essential hypertension. We have identified a missense variant, Glu298Asp, in exon 7 of the eNOS gene and demonstrated that it is associated with both coronary spastic angina and myocardial infarction. To explore the genetic involvement of the eNOS gene in essential hypertension, we examined the possible association between essential hypertension and several polymorphisms including the Glu298Asp variant, variable number tandem repeats in intron 4 (eNOS4b/4a), and two polymorphisms in introns 18 and 23. We performed a large-scale study of genetic association using two independent populations from Kyoto (n=458; 240 normotensive versus 218 hypertensive subjects) and Kumamoto (n=421; 223 normotensive versus 187 hypertensive subjects), Japan. In both groups, a new coding variant, Glu298Asp, showed a strong association with essential hypertension (Kyoto: odds ratio, 2.3 [95% confidence interval, 1.4 to 3.9]; Kumamoto: odds ratio, 2.4 [95% confidence interval, 1.4 to 4.0]). The allele frequencies of 298Asp in hypertensive subjects were significantly higher than those in normotensive subjects in both groups (Kyoto: 0.103 versus 0.050, P<0.0017; Kumamoto: 0.120 versus 0.058, P<0.0013, respectively). No such disequilibrium between genotypes was significantly associated with any other polymorphisms we examined; the Glu298Asp variant was also not linked to any other polymorphisms. In conclusion, the Glu298Asp missense variant was significantly associated with essential hypertension, which suggests that it is a genetic susceptibility factor for essential hypertension.

Significance of ventricular myocytes and nonmyocytes interaction during cardiocyte hypertrophy : Evidence for endothelin-1 as a paracrine hypertrophic factor from cardiac nonmyocytes

BACKGROUND In cardiac hypertrophy, both excessive enlargement of cardiac myocytes and progressive interstitial fibrosis are well known to occur simultaneously. In the present study, to investigate the interaction between ventricular myocytes (MCs) and cardiac nonmyocytes (NMCs), mostly fibroblasts, during cardiocytes hypertrophy, we examined the change in cell size and gene expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in cultured MCs as markers for hypertrophy in the neonatal rat ventricular cardiac cell culture system. METHODS AND RESULTS The size of cultured MCs significantly increased in the MC-NMC coculture. Concomitantly, secretions of ANP and BNP into culture media were significantly increased in the MC-NMC coculture compared with in the MC culture (with the possible contamination of NMC <1% of MC). Moreover, in the MC culture, enlargement of MC and an increase in ANP and BNP secretions were induced by treatment with conditioned media of the NMC culture. A considerable amount of endothelin (ET)-1 production was detected in the NMC-conditioned media. BQ-123, an ET-A receptor antagonist, and bosentan, a nonselective ET receptor antagonist, significantly blocked the hypertrophic response of MCs induced by treatment with NMC-conditioned media. Angiotensin II (Ang II) (10(-10) to 10(-6) mol/L) and transforming growth factor-beta1 (TGF-beta1) (10(-13) to 10(-9) mol/L), both of which are known to be cardiac hypertrophic factors, did not induce hypertrophy in MC culture, but both Ang II and TGF-beta1 increased the size of MCs and augmented ANP and BNP productions in the MC-NMC coculture. This hypertrophic activity of Ang II and TGF-beta1 was associated with the potentiation of ET-1 production in the MC-NMC coculture, and the effect of Ang II or TGF-beta1 on the secretions of ANP and BNP in the coculture was significantly suppressed by pretreatment with BQ-123. CONCLUSIONS These results demonstrate that NMCs regulate MC hypertrophy at least partially via ET-1 secretion and that the interaction between MCs and NMCs plays a critical role during the process of Ang II- or TGF-beta1-induced cardiocyte hypertrophy.

CT Scan Findings of Emphysema Predict Mortality in COPD

BACKGROUND Emphysematous change as assessed by CT imaging has been reported to correlate with COPD prognostic factors such as FEV(1) and diffusing capacity of the lung for carbon monoxide (Dlco). However, few studies have assessed the relationship between CT scan assessment and COPD mortality from mild to severe stages of the disease. In this study, we analyzed this relationship in patients with various stages of COPD. METHODS Two hundred and fifty-one outpatients with stable COPD were included in the study. CT scan and pulmonary function tests were performed at study entry in a single institution. The percentage of low attenuation area was measured to quantitatively evaluate emphysematous change with a custom-made software. Prognostic data also were collected, and the median follow-up time was 8 years. RESULTS Of the 251 patients, 79 died, with 40 classified as respiratory deaths not involving lung cancer. Univariate Cox analysis revealed that emphysematous change as assessed by CT scan, lung function, age, or BMI were significantly correlated with mortality. Multivariate analysis revealed that emphysematous change as assessed by CT scan had the best association with mortality. CONCLUSIONS Emphysematous change as assessed by CT scan predicts respiratory mortality in outpatients with various stages of COPD.

Impact of gastro-oesophageal reflux disease symptoms on COPD exacerbation

Background: The association between gastro-oesophageal reflux disease (GORD) and chronic obstructive pulmonary disease (COPD) exacerbation has so far remained unclear. Objective: To prospectively establish the clinical significance of GORD symptoms on exacerbation. Methods: 82 patients with COPD and 40 age matched controls were enrolled in this study. Symptoms were evaluated by a questionnaire using the Frequency Scale for the Symptoms of GORD (FSSG). Patients with COPD were prospectively surveyed for 6 months, and episodes of exacerbation were identified using a diary based on modified Anthonisen’s criteria. Exhaled breath condensate (EBC) pH was measured in both groups, and induced sputum was evaluated in patients with COPD. Results: Positive GORD symptoms were reported in 22 (26.8%) patients with COPD and in five (12.5%) controls (p = 0.10). The frequency of exacerbations was significantly associated with the FSSG score (p = 0.03, r = 0.24, 95% CI 0.02 to 0.43). Multiple regression analysis revealed that GORD symptoms were significantly associated with the occurrence of exacerbations (p<0.01; relative risk 6.55, 95% CI 1.86 to 23.11). EBC pH was inversely correlated with FSSG score in both groups (p = 0.01, r = –0.37, 95% CI –0.55 to −0.14 in patients with COPD, and p<0.01, r = –0.45, 95% CI –0.67 to −0.16 in control subjects). Conclusions: GORD symptoms were identified as an important factor associated with COPD exacerbation.

THE EFFECTS OF THE SELECTIVE ROCK INHIBITOR, Y27632, ON ET-1-INDUCED HYPERTROPHIC RESPONSE IN NEONATAL RAT CARDIAC MYOCYTES : POSSIBLE INVOLVEMENT OF RHO/ROCK PATHWAY IN CARDIAC MUSCLE CELL HYPERTROPHY

A small GTPase, Rho, participates in agonist‐induced cytoskeletal organization and gene expression in many cell types including cardiac myocytes. However, little is known about the functions of Rhos downstream targets in cardiac myocytes. We examined the role of ROCK, a downstream target of Rho, in ET‐1‐induced hypertrophic response. Y27632, a selective ROCK inhibitor, inhibited ET‐1‐induced increases in natriuretic peptide production, cell size, protein synthesis, and myofibrillar organization. In addition, a dominant‐negative mutant of p160ROCK suppressed ET‐1‐induced transcription of the BNP gene. These findings suggest that the Rho/ROCK pathway is an important component of ET‐1‐induced hypertrophic signals in cardiac myocytes.

Involvement of Cardiotrophin-1 in Cardiac Myocyte-Nonmyocyte Interactions During Hypertrophy of Rat Cardiac Myocytes In Vitro

BACKGROUND The mechanism responsible for cardiac hypertrophy is currently conceptualized as having 2 components, mediated by cardiac myocytes and nonmyocytes, respectively. The interaction between myocytes and nonmyocytes via growth factors and/or cytokines plays an important role in the development of cardiac hypertrophy. We found that cardiac myocytes showed hypertrophic changes when cocultured with cardiac nonmyocytes. Cardiotrophin-1 (CT-1), a new member of the interleukin-6 family of cytokines, was identified by its ability to induce hypertrophic response in cardiac myocytes. In this study, we used the in vitro coculture system to examine how CT-1 is involved in the interaction between cardiac myocytes and nonmyocytes during the hypertrophy process. METHODS AND RESULTS RNase protection assay revealed that CT-1 mRNA levels were 3. 5 times higher in cultured cardiac nonmyocytes than in cultured cardiac myocytes. We developed anti-CT-1 antibodies and found that they significantly inhibited the increased atrial and brain natriuretic peptide secretion and protein synthesis characteristic of hypertrophic changes of myocytes in the coculture. In addition, non-myocyte-conditioned medium rapidly elicited tyrosine phosphorylation of STAT3 and induced an increase in natriuretic peptide secretion and protein synthesis in cultured cardiac myocytes; these effects were partially suppressed by anti-CT-1 antibodies. Finally, the hypertrophic effects of CT-1 and endothelin-1, which we had previously implicated in the hypertrophic activity in the coculture, were additive in cardiac myocytes. CONCLUSIONS These results show that CT-1 secreted from cardiac nonmyocytes is significantly involved in the hypertrophic changes of cardiac myocytes in the coculture and suggest that CT-1 is an important local regulator in the process of cardiac hypertrophy.

Relationship Between Pulmonary Emphysema and Osteoporosis Assessed by CT in Patients With COPD

BACKGROUND Osteoporosis is one of the important systemic features of COPD. Although COPD itself is regarded as one risk factor for osteoporosis, the relationship between the extent of emphysema and reduced bone density is still unclear. Our first aim was therefore to measure vertebral bone density and the percentage of low-attenuation area (LAA%) in the lungs using chest CT scans in COPD patients. Our second aim was to investigate the relationships among CT scan measurements, anthropometric parameters, and pulmonary function. METHODS Chest CT scans and pulmonary function tests were performed in 65 male patients with COPD. Using CT images, the CT scan density of the thoracic and lumbar vertebrae (T4, T7, T10, and L1) and the LAA% were measured quantitatively, and their correlations were analyzed. RESULTS Linear regression analyses revealed that LAA% had a significant negative correlation with bone mineral density (BMD) [r = -0.522]. In addition, multiple regression analysis showed that only LAA% and body mass index (BMI) were predictive of BMD among age, BMI, smoking index, FEV(1), arterial blood gas, and LAA%. CONCLUSIONS The extent of pulmonary emphysema significantly correlated with reduced bone density. Our study suggested that COPD itself could be a risk factor for osteoporosis and that chest CT scanning is useful for the management of COPD as a systemic disease.

The Neuron-Restrictive Silencer Element–Neuron-Restrictive Silencer Factor System Regulates Basal and Endothelin 1-Inducible Atrial Natriuretic Peptide Gene Expression in Ventricular Myocytes

ABSTRACT Induction of the atrial natriuretic peptide (ANP) gene is a common feature of ventricular hypertrophy. A number of cis-acting enhancer elements for several transcriptional activators have been shown to play central roles in the regulation of ANP gene expression, but much less is known about contributions made by transcriptional repressors. The neuron-restrictive silencer element (NRSE), also known as repressor element 1, mediates repression of neuronal gene expression in nonneuronal cells. We found that NRSE, which is located in the 3′ untranslated region of the ANP gene, mediated repression of ANP promoter activity in ventricular myocytes and was also involved in the endothelin 1-induced increase in ANP gene transcription. The repression was conferred by a repressor protein, neuron-restrictive silencer factor (NRSF). NRSF associated with the transcriptional corepressor mSin3 and formed a complex with histone deacetylase (HDAC) in ventricular myocytes. Trichostatin A (TSA), a specific HDAC inhibitor, relieved NRSE-mediated repression of ANP promoter activity, and chromatin immunoprecipitation assays revealed the involvement of histone deacetylation in NRSE-mediated repression of ANP gene expression. Furthermore, in myocytes infected with recombinant adenovirus expressing a dominant-negative form of NRSF, the basal level of endogenous ANP gene expression was increased and a TSA-induced increase in ANP gene expression was apparently attenuated, compared with those in myocytes infected with control adenovirus. Our findings show that an NRSE-NRSF system plays a key role in the regulation of ANP gene expression by HDAC in ventricular myocytes and provide a new insight into the role of the NRSE-NRSF system outside the nervous system.

Body mass index in male patients with COPD: correlation with low attenuation areas on CT

Background: Chronic obstructive pulmonary disease (COPD) is characterised by the presence of airflow limitation caused by loss of lung elasticity and/or airway narrowing. The pathological hallmark of loss of lung elasticity is emphysema, and airway wall remodelling contributes to the airway narrowing. Using CT, these lesions can be assessed by measuring low attenuation areas (LAA) and airway wall thickness/luminal area, respectively. As previously reported, COPD can be divided into airway dominant, emphysema dominant and mixed phenotypes using CT. In this study, it is postulated that a patient’s physique may be associated with the relative contribution of these lesions to airflow obstruction. Methods: CT was used to evaluate emphysema and airway dimensions in 201 patients with COPD. Emphysema was evaluated using percentage of LAA voxels (LAA%) and airway lesion was estimated by percentage wall area (WA%). Patients were divided into four phenotypes using LAA% and WA%. Results: Body mass index (BMI) was significantly lower in the higher LAA% phenotype (ie, emphysema dominant and mixed phenotypes). BMI correlated with LAA% (ρ = −0.557, p<0.0001) but not with WA%. BMI was significantly lower in the emphysema dominant phenotype than in the airway dominant phenotype, while there was no difference in forced expiratory volume in 1 s %predicted between the two. Conclusion: A low BMI is associated with the presence of emphysema, but not with airway wall thickening, in male smokers who have COPD. These results support the concept of different COPD phenotypes and suggest that there may be different systemic manifestations of these phenotypes.

Impact of Exacerbations on Emphysema Progression in Chronic Obstructive Pulmonary Disease

RATIONALE Low-attenuation areas assessed by computed tomography reflect the extent of pathological emphysema and correlate with airflow limitation and mortality in patients with chronic obstructive pulmonary disease. The cumulative size distribution of low-attenuation area clusters follows a power law characterized by an exponent, D. The values of D reflect the complexity of the terminal airspace geometry and sensitively detect alveolar structural changes. Exacerbations of chronic obstructive pulmonary disease have a negative impact on lung function and prognosis. However, the impact on emphysema progression remains unclear. OBJECTIVES We investigated the relationship between exacerbation and emphysema progression assessed by computed tomography in patients with chronic obstructive pulmonary disease. METHODS Exacerbations were prospectively recorded for 2 years. Annual changes in computed tomography parameters of emphysema were compared between patients with and without a history of exacerbations. MEASUREMENTS AND MAIN RESULTS In patients with exacerbations, increases in the percentage of low-attenuation areas and decreases in D were greater than in patients without exacerbations. To interpret these results, we established a novel simulation model and found that not only enlargement of preexisting low-attenuation areas but also coalescence of adjoining low-attenuation areas due to alveolar wall destruction caused emphysema progression in patients with exacerbations. CONCLUSIONS This is the first longitudinal study to demonstrate that exacerbations are involved in emphysema progression in patients with chronic obstructive pulmonary disease. Emphysema progression should be evaluated as part of the outcomes of exacerbations in the management of chronic obstructive pulmonary disease.