Eisuke Amiya

Thrombomodulin Is a Clock-controlled Gene in Vascular Endothelial Cells

Cardiovascular diseases are closely related to circadian rhythm, which is under the control of an internal biological clock mechanism. Although a biological clock exists not only in the hypothalamus but also in each peripheral tissue, the biological relevance of the peripheral clock remains to be elucidated. In this study we searched for clock-controlled genes in vascular endothelial cells using microarray technology. The expression of a total of 229 genes was up-regulated by CLOCK/BMAL2. Among the genes that we identified, we examined the thrombomodulin (TM) gene further, because TM is an integral membrane glycoprotein that is expressed primarily in vascular endothelial cells and plays a major role in the regulation of intravascular coagulation. TM mRNA and protein expression showed a clear circadian oscillation in the mouse lung and heart. Reporter analyses, gel shift assays, and chromatin immunoprecipitation analyses using the TM promoter revealed that a heterodimer of CLOCK and BMAL2 binds directly to the E-box of the TM promoter, resulting in TM promoter transactivation. Indeed, the oscillation of TM gene expression was abolished in clock mutant mice, suggesting that TM expression is regulated by the clock gene in vivo. Finally, the phase of circadian oscillation of TM mRNA expression was altered by temporal feeding restriction, suggesting TM gene expression is regulated by the peripheral clock system. In conclusion, these data suggest that the peripheral clock in vascular endothelial cells regulates TM gene expression and that the oscillation of TM expression may contribute to the circadian variation of cardiovascular events.

The Relationship between Vascular Function and the Autonomic Nervous System

Endothelial dysfunction and autonomic nervous system dysfunction are both risk factors for atherosclerosis. There is evidence demonstrating that there is a close interrelationship between these two systems. In hypertension, endothelial dysfunction affects the pathologic process through autonomic nervous pathways, and the pathophysiological process of autonomic neuropathy in diabetes mellitus is closely related with vascular function. However, detailed mechanisms of this interrelationship have not been clearly explained. In this review, we summarize findings concerning the interrelationship between vascular function and the autonomic nervous system from both experimental and clinical studies. The clarification of this interrelationship may provide more comprehensive risk stratification and a new effective therapeutic strategy against atherosclerosis.

Brief report: Takayasu arteritis and ulcerative colitis: High rate of co-occurrence and genetic overlap

Takayasu arteritis (TAK) is a systemic vasculitis affecting large arteries and large branches of the aorta. Ulcerative colitis (UC) is a prevalent autoimmune colitis. Since TAK and UC share HLA–B*52:01 and IL12B as genetic determinants, and since there are case reports of the co‐occurrence of these diseases, we hypothesized that UC is a common complication of TAK. We undertook this study to perform a large‐scale analysis of TAK, both to evaluate the prevalence of concurrent cases of TAK and UC and to identify and estimate susceptibility genes shared between the 2 diseases.

VEGF‐A induces its negative regulator, soluble form of VEGFR‐1, by modulating its alternative splicing

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.

Takayasu arteritis and ulcerative colitis: high rate of co-occurrence and genetic overlap.

Takayasu arteritis (TAK) is a systemic vasculitis affecting large arteries and large branches of the aorta. Ulcerative colitis (UC) is a prevalent autoimmune colitis. Since TAK and UC share HLA–B*52:01 and IL12B as genetic determinants, and since there are case reports of the co‐occurrence of these diseases, we hypothesized that UC is a common complication of TAK. We undertook this study to perform a large‐scale analysis of TAK, both to evaluate the prevalence of concurrent cases of TAK and UC and to identify and estimate susceptibility genes shared between the 2 diseases.

Melatonin ameliorates Angiotensin II-induced vascular endothelial damage via its antioxidative properties

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 p47phox 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.

Angiotensin II impairs endothelial nitric-oxide synthase bioavailability under free cholesterol-enriched conditions via intracellular free cholesterol-rich membrane microdomains.

Background: Free cholesterol forms membrane microdomains in endothelial cells. Results: Free cholesterol loading formed intracellular vesicles with free cholesterol-rich microdomains that were shifted toward late endosomes/lysosomes by angiotensin II, resulting in impairment of endothelial NOS availability. Conclusion: Angiotensin II decreased the bioavailability of endothelial NOS in a free cholesterol-enriched condition. Significance: Free cholesterol-rich microdomains are crucial platforms of endothelial NOS availability. 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.

Improvement of endothelial function in parallel with the amelioration of dry cough and dyspnea due to interstitial pneumonia by intravenous cyclophosphamide pulse therapy in patients with systemic sclerosis : a preliminary report of two cases

Intravenous cyclophosphamide pulse therapy (IVCY) exerts its efficacy against interstitial lung disease (ILD) associated with systemic sclerosis (SSc) by restoring vascular injuries as well as aberrant immune activation. We recently experienced two patients with SSc-ILD in whom the values of brachial flow-mediated dilation (FMD) reflected the efficacy of IVCY. We herein report the details of these cases and discuss the potential of FMD to predict and evaluate the effect of IVCY on SSc-ILD.

High-Dose Versus Low-Dose Pitavastatin in Japanese Patients With Stable Coronary Artery Disease (REAL-CAD): A Randomized Superiority Trial

Background: Current guidelines call for high-intensity statin therapy in patients with cardiovascular disease on the basis of several previous “more versus less statins” trials. However, no clear evidence for more versus less statins has been established in an Asian population. Methods: In this prospective, multicenter, randomized, open-label, blinded end point study, 13 054 Japanese patients with stable coronary artery disease who achieved low-density lipoprotein cholesterol (LDL-C) <120 mg/dL during a run-in period (pitavastatin 1 mg/d) were randomized in a 1-to-1 fashion to high-dose (pitavastatin 4 mg/d; n=6526) or low-dose (pitavastatin 1 mg/d; n=6528) statin therapy. The primary end point was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal ischemic stroke, or unstable angina requiring emergency hospitalization. The secondary composite end point was a composite of the primary end point and clinically indicated coronary revascularization excluding target-lesion revascularization at sites of prior percutaneous coronary intervention. Results: The mean age of the study population was 68 years, and 83% were male. The mean LDL-C level before enrollment was 93 mg/dL with 91% of patients taking statins. The baseline LDL-C level after the run-in period on pitavastatin 1 mg/d was 87.7 and 88.1 mg/dL in the high-dose and low-dose groups, respectively. During the entire course of follow-up, LDL-C in the high-dose group was lower by 14.7 mg/dL than in the low-dose group (P<0.001). With a median follow-up of 3.9 years, high-dose as compared with low-dose pitavastatin significantly reduced the risk of the primary end point (266 patients [4.3%] and 334 patients [5.4%]; hazard ratio, 0.81; 95% confidence interval, 0.69–0.95; P=0.01) and the risk of the secondary composite end point (489 patients [7.9%] and 600 patients [9.7%]; hazard ratio, 0.83; 95% confidence interval, 0.73–0.93; P=0.002). High-dose pitavastatin also significantly reduced the risks of several other secondary end points such as all-cause death, myocardial infarction, and clinically indicated coronary revascularization. The results for the primary and the secondary composite end points were consistent across several prespecified subgroups, including the low (<95 mg/dL) baseline LDL-C subgroup. Serious adverse event rates were low in both groups. Conclusions: High-dose (4 mg/d) compared with low-dose (1 mg/d) pitavastatin therapy significantly reduced cardiovascular events in Japanese patients with stable coronary artery disease. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01042730.

Effect of add-on aliskiren to type 1 angiotensin receptor blocker therapy on endothelial function and autonomic nervous system in hypertensive patients with ischemic heart disease.

The aim of this study was to evaluate the add‐on effect of aliskiren to valsartan on endothelial‐dependent vasodilation in hypertensive patients with ischemic heart disease (IHD). After 4 weeks of treatment with 80 mg of valsartan, 28 patients were allocated to either continued treatment with valsartan or an add‐on treatment with valsartan plus 150 mg of aliskiren. Aliskiren significantly decreased plasma renin activity, whereas endothelium‐dependent vasodilation measured by flow‐mediated dilation (FMD) did not change. In contrast, heart rate significantly decreased (73.1 ± 9.8 to 66.3 ± 7.0 beats per minute at baseline and 24 weeks, respectively [P = .009]) and the standard deviation of the R‐R intervals (SDNN) significantly increased in the aliskiren group. The add‐on aliskiren to valsartan therapy may not improve endothelial functions, although it significantly reduced resting heart rate via regulation of the autonomic nervous system in hypertensive patients with IHD.