永井 良三

Melatonin is well known to have a beneficial effect on the cardiovascular system, but it remains to be elucidated whether melatonin has a therapeutic effect on the vascular damage induced by the potential vasoactive substance angiotensin II (Ang II). In this study, the effects of melatonin on Ang II-induced vascular endothelial damage were investigated. In cultured vascular endothelial cells, Ang II stimulation increased ROS generation and inhibited eNOS phosphorylation (Ser1177), both of which were clearly restored by pretreatment with melatonin. The translocation of p47(phox) subunit of NADPH oxidase from the cytosol to plasma membrane was promoted in Ang II-treated vascular endothelial cells, which was canceled by melatonin pretreatment. In Ang II-infused rats, increased ROS generation in the aortic wall and impaired endothelial function of the aortic ring were observed, which were rescued by coadministration of melatonin. In vasculature, melatonin receptor agonist ramelteon had the antioxidative effect in the same manner as melatonin by itself. These findings suggest that melatonin directly ameliorates Ang II-induced vascular endothelial damage partly via its antioxidative properties, providing with us the potential rationale for clinical application of melatonin to the prevention from cardiovascular diseases.

BACKGROUND: Restenosis after percutaneous coronary intervention (PCI) is still a great concern even in the recent drug-eluting stent (DES) era. As less invasive and sensitive parameter to detect restenosis is needed, this study was aimed to assess whether the clinical implication of temporal change in plasma BNP levels might be a useful indicator of restenosis after DES implantation. METHODS AND RESULTS: 847 consecutive patients who underwent elective PCI using silorimus-eluting sent (SES) between 2005 and 2009 were analyzed. Primary endpoint was subsequent target-lesion revascularization (TLR) after PCI. There was no significant difference in either baseline (TLR+vs. TLR-: 107.2 ± 172.2 vs. 96.2 ± 175.5 pg/mL, P=0.53) or follow-up plasma B-type natriuretic peptide (BNP) levels (TLR+vs. TLR-: 88.6 ± 111.6 vs. 68.5 ± 226.0 pg/mL, P=0.35) between patients with and without subsequent TLR. Conversely, ratio of follow-up to baseline BNP was significantly higher in patients with TLR (TLR+vs. TLR-: 1.55 ± 1.58 vs. 1.07 ± 1.04, P<0.001). Multivariate analysis using logistic regression showed log transformed BNP-ratio was an independent predictor of TLR (adjusted odds ratio (aOR): 1.94, 95%CI: 1.42-2.66, P<0.001). A closer relationship between BNP elevation greater than 2-fold and subsequent TLR was found (aOR: 2.69, 95%CI: 1.27-5.69, P<0.009). Furthermore, propensity score matching analysis showed that the incidence of subsequent TLR was significantly higher in patients with BNP elevation (P<0.001). CONCLUSION: Serial measurement of plasma BNP levels and its change might be a useful approach to predict restenosis in patients without typical chest symptoms receiving SES.

Vascular endothelial growth factor-A (VEGF-A) is one of the major angiogenic factors, and its actions are primarily mediated through its two membrane receptors, VEGFR-1 and VEGFR-2. A soluble form of VEGFR-1 (sVEGFR-1) sequesters the free form of VEGF-A, and acts as a potent anti-angiogenic factor. While sVEGFR-1 is synthesized as a splice variant of VEGF-R1 gene, the interactions between VEGF-A and sVEGFR-1 remain largely unknown. Here, we show that VEGF-A upregulates sVEGF-R1 expression in human vascular endothelial cells but leaves full-length VEGF-R1 expression unchanged, and that this induction was dependent on the VEGFR-2-protein kinase C-MEK signaling pathway. The VEGF-A-induced sVEGFR-1 upregulation can operate as a negative feedback system, which if modulated can become a novel therapeutic target for regulating pathological angiogenesis.

Vascular endothelial function is impaired in hypercholesterolemia partly because of injury by modified LDL. In addition to modified LDL, free cholesterol (FC) is thought to play an important role in the development of endothelial dysfunction, although the precise mechanisms remain to be elucidated. The aim of this study was to clarify the mechanisms of endothelial dysfunction induced by an FC-rich environment. Loading cultured human aortic endothelial cells with FC induced the formation of vesicular structures composed of FC-rich membranes. Raft proteins such as phospho-caveolin-1 (Tyr-14) and small GTPase Rac were accumulated toward FC-rich membranes around vesicular structures. In the presence of these vesicles, angiotensin II-induced production of reactive oxygen species (ROS) was considerably enhanced. This ROS shifted endothelial NOS (eNOS) toward vesicle membranes and vesicles with a FC-rich domain trafficked toward perinuclear late endosomes/lysosomes, which resulted in the deterioration of eNOS Ser-1177 phosphorylation and NO production. Angiotensin II-induced ROS decreased the bioavailability of eNOS under the FC-enriched condition.

BACKGROUND & AIMS: Dysregulated glucose homeostasis and lipid accumulation characterize non-alcoholic fatty liver disease (NAFLD), but underlying mechanisms are obscure. We report here that Krüppel-like factor 6 (KLF6), a ubiquitous transcription factor that promotes adipocyte differentiation, also provokes the metabolic abnormalities of NAFLD by post-transcriptionally activating PPARα-signaling. METHODS: Mice with either hepatocyte-specific depletion of KLF6 ('ΔHepKlf6') or global KLF6 heterozygosity (Klf6+/-) were fed a high fat diet (HFD) or chow for 8 or 16 weeks. Glucose and insulin tolerance tests were performed to assess insulin sensitivity. Overexpression and knockdown of KLF6 in cultured cells enabled the elucidation of underlying mechanisms. In liver samples from a cohort of 28 NAFLD patients, the expression of KLF6-related target genes was quantified. RESULTS: Mice with global- or hepatocyte-depletion of KLF6 have reduced body fat content and improved glucose and insulin tolerance, and are protected from HFD-induced steatosis. In hepatocytes, KLF6 deficiency reduces PPARα-regulated genes (Trb3, Pepck) with diminished PPARα protein but no change in Pparα mRNA, which is explained by the discovery that KLF6 represses miRNA 10b, which leads to induction of PPARα. In NAFLD patients with advanced disease and inflammation, the expression of miRNA 10b is significantly downregulated, while PEPCK mRNA is upregulated; KLF6 mRNA expression also correlates with TRB3 as well as PEPCK gene expression. CONCLUSIONS: KLF6 increases PPARα activity, whereas KLF6 loss leads to PPARα repression and attenuation of lipid and glucose abnormalities associated with a high fat diet. The findings establish KLF6 as a novel regulator of hepatic glucose and lipid metabolism in fatty liver.

Self-care is a cornerstone for the successful management of heart failure (HF). The purpose of this study was to examine the impacts of HF self-care on prognosis in Japanese patients with HF. A total of 283 HF outpatients (age 64 ± 14, 70% male, 52% HFrEF) were enrolled. We asked patients to answer about their adhevence to 5 self-care behaviors (medication, eating a low-sodium diet, regular exercise, daily weight check, and treatment seeking behavior). On the basis of the results, we classified patients into a good self-care group and a poor self-care group. The primary outcome was HF hospitalization and/or cardiac death. In total, 65% of patients were classified into the poor self-care group. During a median follow-up of 2 years, cardiac events occurred more frequently in the poor self-care group (22% versus 9.6%, P = 0.013). Poor self-care was an independent risk factor for cardiac events in Cox regression analysis adjusted for clinical parameters (hazard ratio = 2.86, P = 0.005). Poor self-care was also associated with an increased number of HF hospitalizations as well as an extended length of hospital stay for HF. Poor knowledge about HF was an independent determinant for poor self-care in multivariate logistic regression analysis (odds ratio = 0.92, P = 0.019). Insufficient self-care is an independent risk factor for cardiac events in Japanese patients with HF.

Simulation studies have been performed in attempts to elucidate the signifi cance of shear and tissue stresses in the progression and rupture of coronary artery plaques, but few studies have analyzed both stresses simultaneously. We analyzed the distributions of shear stress and tissue stress in a model of coronary artery plaque based on intravascular ultrasound data by fluid-structure interaction finite element analysis under physiological pressure and flow. As shown in previous studies, the region of peak shear stress was observed at the proximal side of the plaque where flow velocity was high but its value was at most 10 Pa. On the other hand, 1000-10,000 times greater tissue stress was located in the stenotic region but the location of peak tissue stress was different from that of shear stress. We also found that stenting not only stabilizes the stented segment but also reduces the stress in the adjacent region. Fluid-structure interaction analysis revealed discordance in the distribution of shear and tissue stresses. These two stresses exert distinct influences on the coronary plaque, rupture of which may occur where tissue stress exceeds the plaque strength, which is weakened by pathological processes triggered by shear stress.