研究者詳細 - 伊藤　裕

論文 - 伊藤　裕

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Renin, prorenin and the kidney: a new chapter in an old saga

Ichihara, A., Sakoda, M., Kurauchi-Mito, A., Kaneshiro, Y. and Itoh, H.

J Nephrol 22 （ 3 ） 306 - 11 2009年05月

ISSN 1121-8428

The binding of prorenin to the (pro)renin receptor triggers 2 major pathways: a nonproteolytic conformational change in prorenin to its active form (angiotensin II-dependent pathway) and an intracellular pathway via the (pro)renin receptor itself (angiotensin II-independent pathway). In diabetic animals, an increased plasma prorenin level not only causes the generation of angiotensin II via the angiotensin II-dependent pathway, it also stimulates the transliteration receptors own intracellular signaling pathway in a manner that is independent of the generated angiotensin II. Thus, the administration of a "handle" region peptide (HRP), which acts as a decoy peptide and competitively inhibits the binding of prorenin to the (pro)renin receptor, has a beneficial effect in the kidneys of diabetic animals with low plasma renin levels. However, the benefits of HRP are slightly reduced in animal models of essential hypertension with relatively high plasma renin levels, and these benefits disappear altogether in animal models of hypertension with extremely high plasma renin levels. Thus, in the kidneys of animal models of diabetes and/or hypertension, both renin and prorenin competitively bind to the (pro)renin receptor and contribute to the pathophysiology of nephropathy. Consequently, renin, prorenin and the (pro) renin receptor may be important therapeutic targets for the prevention and regression of nephropathy in patients with diabetes and/or hypertension.

Effects of telmisartan therapy on metabolic profiles and serum high molecular weight (HMW)-adiponectin level in Japanese male hypertensive subjects with abdominal obesity

Komiya, N., Hirose, H., Kawabe, H., Itoh, H. and Saito, I.

J Atheroscler Thromb 16 （ 2 ） 137 - 42 2009年04月

ISSN 1340-3478

AIM: Telmisartan, an angiotensin II receptor blocker (ARB), was reported to have partial peroxisome proliferator-activated receptor gamma (PPAR gamma) activity in vitro. Also, adipocyte-derived protein adiponectin, especially its high molecular weight (HMW) form, has been reported to have beneficial effects on insulin resistance and atherosclerosis. We investigated the effects of 3-month telmisartan therapy on various metabolic parameters, including serum HMW adiponectin and high-sensitivity C-reactive protein (hs-CRP) levels in male hypertensive subjects with abdominal obesity. METHODS: This study included 19 Japanese male hypertensive subjects, aged 51.2+/-7.6 (mean+/-SD) years, and body mass index 27.7+/-4.1 kg/m(2). In these subjects, 14 were naive to telmisartan treatment (40.0+/-15.7 mg daily), and 5 were changed from other ARBs to telmisartan. Serum HMW adiponectin concentration was assayed using HMW-selective ELISA kit. RESULTS: In all 19 subjects, systolic/diastolic blood pressure (BP) decreased from 153/98 to 134/85 mmHg (p<0.001 for both). Serum HMW-adiponectin level increased from 2.06+/-0.81 to 2.40+/-0.96 microg/mL (+16.4%, p=0.017). Body weight, glucose, insulin, lipids and hs-CRP did not change during the study period, and there were no adverse effects in any subject. In the newly administered group (n=14), the results were almost the same: BP decreased from 155/98 to 134/84 mmHg (p=0.0015 for both), and serum HMW-adiponectin level increased from 2.07+/-0.68 to 2.39+/-0.99 microg/mL (+15.5%, p=0.089). CONCLUSION: These data suggest that telmisartan therapy is efficient for controlling BP, and may exert beneficial effects on HMW adiponectin in male hypertensive subjects with abdominal obesity.

Adipogenic differentiation of human induced pluripotent stem cells: comparison with that of human embryonic stem cells

Taura, D., Noguchi, M., Sone, M., Hosoda, K., Mori, E., Okada, Y., Takahashi, K., Homma, K., Oyamada, N., Inuzuka, M., Sonoyama, T., Ebihara, K., Tamura, N., Itoh, H., Suemori, H., Nakatsuji, N., Okano, H., Yamanaka, S. and Nakao, K.

FEBS Lett 583 （ 6 ） 1029 - 33 2009年03月

ISSN 0014-5793

Induced pluripotent stem (iPS) cells were recently established from human fibroblasts. In the present study we investigated the adipogenic differentiation properties of four human iPS cell lines and compared them with those of two human embryonic stem (ES) cell lines. After 12 days of embryoid body formation and an additional 10 days of differentiation on Poly-l-ornithine and fibronectin- coated dishes with adipogenic differentiation medium, human iPS cells exhibited lipid accumulation and transcription of adipogenesis-related molecules such as C/EBPalpha, PPARgamma2, leptin and aP2. These results demonstrate that human iPS cells have an adipogenic potential comparable to human ES cells.

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Induction of anti-whole GAD65 reactivity in vivo results in disease suppression in type 1 diabetes

Kanazawa, Y., Shimada, A., Oikawa, Y., Okubo, Y., Tada, A., Imai, T., Miyazaki, J. and Itoh, H.

J Autoimmun 32 （ 2 ） 104 - 9 2009年03月

ISSN 0896-8411

Most type 1 diabetes mellitus is caused by autoimmune pancreatic beta-cell destruction. Several antigens such as insulin, glutamic acid decarboxylase (GAD) and islet-specific glucose-6-phosphatase catalytic subunit related protein (IGRP) are considered to take part in the autoimmune destructive process. Because the role of GAD in the disease process of type 1 diabetes is still controversial, we investigated the disease phenotype upon in vivo induction of whole GAD65 reactivity using a GAD65 homo knockout NOD splenocytes to NOD-scid transfer system. Splenocytes from 8 to 10-week-old female GAD65 homo knockout (=KOT splenocytes) or age-matched wild type (=WTT splenocytes) NOD mice were transferred into female NOD-scid recipients. As compared to recipients of WTT splenocytes, the onset of diabetes in recipients of KOT splenocytes was significantly delayed (p<0.001). Moreover, TGF-beta expression was enhanced in the pancreas from recipients of KOT splenocytes. Splenocytes from recipients of KOT splenocytes produced IL-10 (/IFN-gamma) upon GAD65 stimulation, whereas those from recipients of WTT splenocytes did not. Based upon these results, we propose that anti-whole GAD65-reactive T cells have the ability to regulate the development of type 1 diabetes.

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High-molecular-weight adiponectin is a predictor of progression to metabolic syndrome: a population-based 6-year follow-up study in Japanese men

Seino, Y., Hirose, H., Saito, I. and Itoh, H.

Metabolism 58 （ 3 ） 355 - 60 2009年03月

ISSN 0026-0495

Adiponectin is an adipocyte-specific secretory protein, which possesses antidiabetic and antiatherosclerotic properties. Adiponectin exists as multimers in serum, and high-molecular-weight (HMW) adiponectin is particularly considered to be the active form of the protein. The objective of the present study was to examine whether decreased HMW adiponectin is a predictor of progression to metabolic syndrome during a 6-year follow-up period in Japanese men. The study subjects were 416 Japanese men without metabolic syndrome, aged 30 to 59 years at baseline, who had participated in annual health checkups in both 2000 and 2006. Low concentration of HMW adiponectin (< or =2.65 microg/mL) was associated with substantially higher hazard ratio of the progression to metabolic syndrome after adjustment for age and body mass index (hazard ratio, 1.561; 95% confidence interval, 1.051-2.292; P = .028). The number of subjects with the progression to metabolic syndrome in each tertile based on baseline HMW adiponectin concentration was significantly different among the 3 groups (HMW adiponectin: chi(2) = 7.473, P = .0238; total adiponectin: chi(2) = 4.477, P = .1066; HMW-total adiponectin ratio: chi(2) = 1.676, P = .4325). It was suggested that decreased HMW adiponectin is a predictor of the progression to metabolic syndrome in a 6-year follow-up study of Japanese men. Furthermore, it was suggested longitudinally that measuring HMW adiponectin is efficient to predict the progression to metabolic syndrome compared with measuring total adiponectin or HMW-total adiponectin ratio.

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Angiotensin II reduces mitochondrial content in skeletal muscle and affects glycemic control

Mitsuishi, M., Miyashita, K., Muraki, A. and Itoh, H.

Diabetes 58 （ 3 ） 710 - 7 2009年03月

ISSN 0012-1797

OBJECTIVE: Blockade of angiotensin (Ang) II has been shown to prevent new-onset type 2 diabetes. We focused on the effects of AngII on muscle mitochondria, especially on their biogenesis, as an underlining mechanism of type 2 diabetes. RESEARCH DESIGN AND METHODS: C2C12 cells and C57bl/6 mice were used to examine roles for AngII in the regulation of muscle mitochondria and to explore whether the effect was mediated by type 1 AngII receptor (AT1R) or type 2 receptor (AT2R). RESULTS: C2C12 cells treated with 10(-8)-10(-6) mol/l AngII reduced the mitochondrial content associated with downregulation of the genes involved in mitochondrial biogenesis. The action of AngII was diminished by blockade of AT2R but not AT1R, whereas overexpression of AT2R augmented the effect. AngII increased mitochondrial ROS and decreased mitochondrial membrane potential, and these effects of AngII were significantly suppressed by blockade of either AT1R or AT2R. Chronic AngII infusion in mice also reduced muscle mitochondrial content in association with increased intramuscular triglyceride and deteriorated glycemic control. The AngII-induced reduction in muscle mitochondria in mice was partially, but significantly, reversed by blockade of either AT1R or AT2R, associated with increased fat oxidation, decreased muscle triglyceride, and improved glucose tolerance. Genes involved in mitochondrial biogenesis were decreased via AT2R but not AT1R under these in vivo conditions. CONCLUSIONS: Taken together, these findings imply the novel roles for AngII in the regulation of muscle mitochondria and lipid metabolism. AngII reduces mitochondrial content possibly through AT1R-dependent augmentation of their degradation and AT2R-dependent direct suppression of their biogenesis.

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FOXP3/Scurfin gene polymorphism is associated with adult onset type 1 diabetes in Japanese, especially in women and slowly progressive-type patients

Iwase, K., Shimada, A., Kawai, T., Okubo, Y., Kanazawa, Y., Irie, J., Oikawa, Y., Hirose, H., Maruyama, T. and Itoh, H.

Autoimmunity 42 （ 2 ） 159 - 67 2009年02月

ISSN 0891-6934

PURPOSE: Some reports have shown that the cause of type 1 diabetes is associated with dysfunction of regulatory T cells (Tregs). The FOXP3/Scurfin gene is known to be a master gene of Tregs. Therefore, we tried to analyze the relation between the gene polymorphism and adult onset type 1 diabetes and its subtype in the Japanese population. METHODS: In this study, we recruited 316 Japanese patients with type 1 diabetes (155 male and 161 female, mean onset age 35.4 years) and 432 healthy Japanese controls (263 male and 169 female, mean age 44.4 years). Then we subdivided the patients by onset type, sex, and islet-associated autoantibody positivity. RESULTS: The genotype frequency of (GT)(16)/(GT)(16) in female patients with overall type 1 diabetes was especially lower than that in controls (19.9% vs. 38.5%, p = 0.0002). Moreover, the genotype frequency of (GT)(16)/(GT)(16) in female patients with slowly progressive type 1 diabetes was significantly lower than that in controls (15.4% vs. 38.5%, p = 0.002). CONCLUSION: Our data showed that the (GT)n microsatelloite polymorphism in the FOXP3/Scrufin gene was associated with Japanese adult onset type 1 diabetes, especially in females, and slowly progressive type 1 diabetes.

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Close examination of steroidogenesis disorders in a DOC- and progesterone-producing adrenocortical carcinoma

Sone, M., Shibata, H., Homma, K., Tamura, N., Akahira, J., Hamada, S., Yahata, M., Fukui, N., Itoh, H., Sasano, H. and Nakao, K.

Endocrine 35 （ 1 ） 25 - 33 2009年02月

ISSN 1355-008X

We report a case of hypertension, hypokalemia, and amenorrhea accompanying an adrenocortical carcinoma. A 27-year-old woman was admitted to our hospital because of a left adrenal incidentaloma. She presented with hypertension, hypokalemia, and amenorrhea; her plasma renin activity was low, but her plasma aldosterone concentration was normal, as were cortisol and androgens. By contrast, her serum concentrations of deoxycorticosterone (DOC), 18-hydroxydeoxycorticosterone, and progesterone were high, and her urinary steroid profile showed elevated secretion of 17-deoxysteroids and 11-deoxysteroids (progesterone, DOC, 11-dehydrocorticosterone, and 11-deoxycortisol), and 3beta-hydroxy 5-en steroids (pregnenolone, 17-hydroxypregnenolone, and DHEA). Decreased ratios of metabolites of (1) 17-OHpregnenolone to pregnenolone and 17-OHprogesterone to progesterone, (2) corticosterone to DOC and cortisol to 11-deoxycortisol, and (3) progesterone to pregnenolone, 17-OHprogesterone to 17-OHpregnenolone and androstenedione to DHEA suggested the impairment of 17alpha-hydroxylase, 11beta-hydroxylase, and 3beta-HSD activities, respectively. After the tumor was removed, levels of all adrenal steroids were normalized. Based on the Weiss criteria, the tumor was diagnosed as an adrenocortical carcinoma, and immunohistochemical analysis of steroidogenic enzymes revealed disorganized steroidogenesis in the tumor tissue. With adrenocortical carcinomas, heterogeneity of individual steroid producing enzymes within tumor cells can lead to hypersecretion of various steroid intermediates, even when steroid end products are within the normal range.

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[Metabolic syndrome]

Mitsuishi, M., Miyashita, K. and Itoh, H.

Nihon Rinsho 67 （ 2 ） 321 - 6 2009年02月

ISSN 0047-1852

Metabolic syndrome, which is consisted of hypertension, dyslipidemia and impaired glucose tolerance, is one of the most significant lifestyle-related disorders that lead to cardiovascular diseases. Among many upstream factors that are related to metabolic syndrome, obesity, especially visceral obesity, plays an essential role in its pathogenesis. In recent studies, possible mechanisms which connect obesity to metabolic syndrome have been elucidated, such as inflammation, abnormal secretion of adipokines and mitochondrial dysfunction. In this review, we focus on the relationship between obesity and metabolic syndrome; and illustrate how visceral obesity contributes to, and how the treatments for obesity act on metabolic syndrome.

Drug discovery for overcoming chronic kidney disease (CKD): new therapy for CKD by a (pro)renin-receptor-blocking decoy peptide

Ichihara, A., Sakoda, M., Kurauchi-Mito, A., Narita, T., Kinouchi, K. and Itoh, H.

J Pharmacol Sci 109 （ 1 ） 20 - 3 2009年01月

ISSN 1347-8613

Discovery of the (pro)renin receptor uncovered a novel function of renin/prorenin as the receptor ligands in addition to the enzyme and its precursor. The bindings of renin and prorenin to the (pro)renin receptor trigger two major pathways: the angiotensin II-dependent pathway as a result of the enzymatic activation of renin/prorenin and the angiotensin II-independent intracellular pathway involving hypertrophic, hyperplastic, and profibrotic signals. A specific blocker of the receptor was discovered through identification of the amino acid sequence of prorenin prosegment that binds to the receptor and leads to non-proteolytic conversion of prorenin to its active form. A peptide containing this sequence was found to block the binding of prorenin to its receptor. Its infusion in animal models of diabetes and low-renin hypertension significantly inhibited the development and progression of nephropathy, but (pro)renin receptor blockade had no benefit in the clipped kidney of 2K1C rats or rat models of high-renin hypertension. Since renin is still active without a (pro)renin receptor, (pro)renin-receptor blockade elicits a maximum benefit under low-renin conditions. Thus, (pro)renin-receptor blockade can be a useful therapy for chronic kidney disease with low renin levels in the plasma.

"Pulse" treatment with high-dose angiotensin blocker reverses renal arteriolar hypertrophy and regresses hypertension

Ishiguro, K., Hayashi, K., Sasamura, H., Sakamaki, Y. and Itoh, H.

Hypertension 53 （ 1 ） 83 - 9 2009年01月

ISSN 0194-911

One ultimate goal of hypertension therapy is to cause permanent reversal ("regression") of already established hypertension. Our aim was to examine whether high-dose "pulse" treatment with a renin-angiotensin system inhibitor could cause regression of established hypertension and to link this action to reversal of arteriolar hypertrophy and changes in vascular matrix metalloproteinase activities. First, 16-week-old male spontaneously hypertensive rats (n=60) were pulse treated for 2 weeks with high-dose angiotensin-converting enzyme inhibitor (enalapril), angiotensin receptor blocker (candesartan), calcium channel blocker (nifedipine), or vasodilator (hydralazine) with or without salt restriction, and the long-term effects on blood pressure were examined. Second, spontaneously hypertensive rats were treated with angiotensin receptor blocker or calcium channel blocker, and the effects on renal gene expressions, arteriolar structure, and vascular matrix metalloproteinase were compared. Treatment of spontaneously hypertensive rats with different antihypertensive agents caused apparently similar reductions in blood pressure during the course of the pulse treatment, within the limitations of the tail-cuff method. After cessation of medications, blood pressure in the rats treated with renin-angiotensin system inhibitor remained reduced by >30 to 40 mm Hg for 4 months. No such effect was seen with calcium channel blocker or vasodilator. The 2-week angiotensin receptor blocker treatment induced a marked reversal of the arteriolar hypertrophy specifically in the small (30 to 100 microm) renal arterioles, together with increased expression and activity of matrix metalloproteinase-13. In conclusion, transient high-dose pulse treatment with angiotensin receptor blocker caused changes in vascular matrix metalloproteinase activity, specific reversal of renal arteriolar hypertrophy, and regression of hypertension in spontaneously hypertensive rats.

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Relation of blood pressure quantitative trait locus on rat chromosome 1 to hyperactivity of rostral ventrolateral medulla

Iigaya, K., Kumagai, H., Nabika, T., Harada, Y., Onimaru, H., Oshima, N., Takimoto, C., Kamayachi, T., Saruta, T. and Itoh, H.

Hypertension 53 （ 1 ） 42 - 8 2009年01月

ISSN 0194-911

Genetic factors that induce essential hypertension have been examined using genome-wide linkage analyses. A quantitative trait locus (QTL) region that is closely linked to hypertension has been found on chromosome 1 in stroke-prone spontaneously hypertensive rats (SHRSPs). We used 2 congenic rats in which the blood pressure QTL on rat chromosome 1 was introgressed from SHRSP/Izm to Wistar-Kyoto (WKY)/Izm (WKYpch1.0) and from WKY/Izm to SHRSP/Izm (SHRSPwch1.0) rats by repeated backcrossing. Previous studies reported that the intermediate phenotype of this QTL for hypertension is characterized by the hyperactivity of the sympathetic nervous system in response to physiological and psychological stress. We performed intracellular patch-clamp recordings of rostral ventrolateral medulla (RVLM) neurons from WKY, WKYpch1.0, SHRSPwch1.0, and SHRSPs and compared the basal electrophysiological activities of RVLM neurons and the responses of these neurons to angiotensin II. The basal membrane potential of RVLM neurons from WKYpch1.0 was significantly "shallower" than that of the neurons from WKY. The depolarization of RVLM neurons from WKYpch1.0 in response to angiotensin II was significantly larger than that in neurons from WKY rats, whereas the depolarization of RVLM neurons from SHRSPwch1.0 was significantly smaller than that in neurons from SHRSPs. The response to angiotensin II of RVLM neurons from WKYpch1.0 and SHRSPs was sustained even after the blockade of all of the synaptic transmissions using tetrodotoxin. The QTL on rat chromosome 1 was primarily related to the postsynaptic response of RVLM bulbospinal neurons to brain angiotensin II, whereas both the QTL and other genomic regions influenced the basal activity of RVLM neurons.

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Add-on benefits of amlodipine and thiazide in nondiabetic chronic kidney disease stage 1/2 patients treated with valsartan

Kaneshiro, Y., Ichihara, A., Sakoda, M., Kurauchi-Mito, A., Kinouchi, K. and Itoh, H.

Kidney Blood Press Res 32 （ 1 ） 51 - 8 2009年

ISSN 1420-4096

Hypertension frequently requires combination therapy to attain efficient control to prevent cardiovascular diseases effectively. This study was conducted to determine which add-on treatment is better, namely calcium channel blockers or diuretics, in improving vascular damage. In 70 nondiabetic chronic kidney disease stage 1/2 patients who had been already treated with angiotensin II type 1 receptor blocker valsartan for at least 12 months, amlodipine or hydrochlorothiazide was added to their existing medication. Pulse wave velocity (PWV), intima-media thickness (IMT) of the carotid arteries, urinary albumin excretion (UAE), and 24-hour ambulatory blood pressure (BP) were determined before and 12 months after the start of add-on treatments. Add-on amlodipine and add-on hydrochlorothiazide significantly and similarly decreased 24-hour ambulatory BP by 18 and 19 mm Hg, respectively, PWV by 206 and 184 cm/s, respectively, and UAE, but did not change the IMT. The decreases in BP significantly contributed to the decreases in PWV and UAE and suggested that the decrease in serum cholesterol level brought about by add-on amlodipine also contributed to the decrease in UAE. These results suggest that 12 months of add-on treatment with either amlodipine or hydrochlorothiazide could have beneficial effects in nondiabetic chronic kidney disease stage 1/2 patients already being treated with valsartan.

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Association of (pro)renin receptor mRNA expression with angiotensin-converting enzyme mRNA expression in human artery

Takemitsu, T., Ichihara, A., Kaneshiro, Y., Sakoda, M., Kurauchi-Mito, A., Narita, T., Kinouchi, K., Yamashita, N. and Itoh, H.

Am J Nephrol 30 （ 4 ） 361 - 70 2009年

ISSN 0250-8095

BACKGROUND/AIMS: A significant role of (pro)renin receptor in the pathogenesis of end-organ damage has been suggested only in animal studies. This study was conducted to examine the mRNA expression of (pro)renin receptor in human artery. METHODS: In 141 kidney failure patients, the mRNA was harvested from arterial fragments obtained during surgery constructing an arteriovenous access for hemodialysis therapy, and expression levels of (pro)renin receptor and other components of the renin-angiotensin system were determined. RESULTS: Arterial (pro)renin receptor expression was similar in diabetic and non-diabetic patients, although plasma prorenin levels were significantly higher in the diabetic patients than in the non-diabetic patients. The arterial (pro)renin receptor mRNA levels of the hypertensive patients, who had not been treated with either angiotensin-converting enzyme (ACE) inhibitors or angiotensin II type 1 receptor blockers, were significantly lower than those of the patients who had been treated with either drug. Multiple regression analyses showed a significant association with a large coefficient between the arterial mRNA level of the (pro)renin receptor and the arterial mRNA level of ACE; this significant association disappeared in patients who had been treated with either drug. CONCLUSION: (Pro)renin receptor may contribute to the generation of arterial angiotensin II in kidney failure patients.

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(Pro)renin receptor promotes choroidal neovascularization by activating its signal transduction and tissue renin-angiotensin system

Satofuka, S., Ichihara, A., Nagai, N., Noda, K., Ozawa, Y., Fukamizu, A., Tsubota, K., Itoh, H., Oike, Y. and Ishida, S.

Am J Pathol 173 （ 6 ） 1911 - 8 2008年12月

ISSN 0002-9440

The receptor-associated prorenin system (RAPS) refers to pathogenic mechanisms whereby prorenin binding to its receptor activates both the tissue renin-angiotensin system (RAS) and RAS-independent intracellular signaling pathways. Although we found significant involvement of angiotensin II type 1 receptor (AT1-R)-mediated inflammation in choroidal neovascularization (CNV), a central abnormality of vision-threatening age-related macular degeneration, the association of receptor-associated prorenin system with CNV has not been defined. Here, (pro)renin receptor blockade in a murine model of laser-induced CNV led to the significant suppression of CNV together with macrophage infiltration and the up-regulation of intercellular adhesion molecule-1, (ICAM-1) monocyte chemotactic protein-1, (MCP-1) vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-1, and VEGFR-2. To clarify the role of signal transduction via the (pro)renin receptor in CNV, we used mice in which renin-angiotensin system was deactivated by either the pharmacological blockade of AT1-R with losartan or the genetic ablation of AT1-R or angiotensinogen. Compared with wild-type controls, these mice exhibited significant reduction of CNV and macrophage infiltration, both of which were further suppressed by (pro)renin receptor blockade. The (pro)renin receptor and phosphorylated extracellular signal-regulated kinases (ERK) were co-localized in vascular endothelial cells and macrophages in CNV. (Pro)renin receptor blockade suppressed ERK activation and the production of MCP-1 and VEGF, but not ICAM-1, VEGFR-1, or VEGFR-2, in AT1-R-deficient mice with CNV and in losartan-treated microvascular endothelial cells and macrophages. These results indicate the significant contribution of RAPS to CNV pathogenesis.

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Eradication of Helicobactor pylori may trigger onset of type 1 diabetes: a case report

Tada, A., Komiya, N., Shimada, A., Katsuki, T., Oikawa, Y. and Itoh, H.

Ann N Y Acad Sci 1150 208 - 9 2008年12月

ISSN 0077-8923

In patients with idiopathic thrombocytopenic purpura (ITP), which is considered an autoimmune disease, eradication of Helicobacter pylori cures a significant number of patients. However, here we report an adult patient who developed type 1 diabetes (T1D), which is also considered an autoimmune disease, after eradication of Helicobacter pylori. Although further investigation is needed to understand the pathophysiology of T1D, we would like to emphasize that clinicians should consider the risk of its development after eradication of Helicobactor pylori.

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Activated prorenin as a therapeutic target for diabetic nephropathy

Ichihara, A., Sakoda, M., Mito-Kurauchi, A. and Itoh, H.

Diabetes Res Clin Pract 82 Suppl 1 S63 - 6 2008年11月

ISSN 0168-8227

High plasma prorenin levels in diabetic patients predict microvascular complications, but the mechanism of the connection between these factors has remained unclear. (Pro)renin receptors were recently found in the human kidney, and their distribution in the kidneys include the mesangium and podocytes. The binding of prorenin to the (pro)renin receptor triggers two major pathways: the angiotensin II-dependent pathway as a result of the conversion of prorenin to the active form of prorenin through a conformational change, and the angiotensin II-independent, (pro)renin-receptor-dependent intracellular mitogen-activated protein kinase pathway. To investigate whether the (pro)renin-receptor-dependent pathways contribute to the pathophysiology of the end-organ damage that occurs in diabetes, the handle region peptide, which binds to the receptor and competitively inhibits prorenin from binding to the receptor, was administered to rats with streptozotocin-induced type I diabetes and to a model of type II diabetes, db/db mice. The handle region peptide significantly inhibited the development of end-organ damage in these diabetic animals, and had a greater benefit than angiotensin-converting enzyme inhibitors in diabetic angiotensin II-type 1a-receptor-deficient mice. In addition, the infusion of the handle region peptide in animals with streptozotocin-induced type I diabetes significantly regressed the nephropathy that had already occurred. These results suggest that prorenin and the (pro)renin receptor play a pivotal role in the pathophysiology of diabetic nephropathy. Receptor-bound prorenin may prove useful as an important therapeutic target for the prevention and regression of end-organ damage in patients with diabetes.

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Cardio-ankle vascular index and ankle pulse wave velocity as a marker of arterial fibrosis in kidney failure treated by hemodialysis

Ichihara, A., Yamashita, N., Takemitsu, T., Kaneshiro, Y., Sakoda, M., Kurauchi-Mito, A. and Itoh, H.

Am J Kidney Dis 52 （ 5 ） 947 - 55 2008年11月

ISSN 0272-6386

BACKGROUND: Patients with kidney failure treated with hemodialysis have a high incidence of cardiovascular diseases caused by accelerated arteriosclerosis. However, accurate evaluation of the extent of arteriosclerosis is difficult. This study sought to compare the strength of predictions of arterial fibrosis by using a new parameter, the cardio-ankle vascular index (CAVI), versus pulse wave velocity (PWV) in patients with kidney failure treated with hemodialysis. STUDY DESIGN: Diagnostic test study. SETTING & PARTICIPANTS: 103 patients with kidney failure undergoing surgical construction of an arteriovenous access for hemodialysis therapy. INDEX TEST: CAVI and PWV. REFERENCE TEST: Arterial fibrosis, evaluated by using Masson trichrome stain on part of the brachial artery obtained during surgery, expressed as percentage of fibrosis of the layer of vascular smooth muscle cells. RESULTS: Median percentage of arterial stiffness was 52.85%. Mean PWV and CAVI were 18.3 +/- 5.6 (SD) m/s and 9.9 +/- 2.6, respectively. Multivariate regression analysis showed that arterial fibrosis was significantly associated with older age (0.247%/y; 95% confidence interval, 0.013 to 0.482) and CAVI (6.117%/unit; 95% confidence interval, 4.764 to 4.740), but not with systolic blood pressure (0.039%/mm Hg; 95% confidence interval, -0.076 to 0.153) or PWV (-0.044%/m/s; 95% confidence interval, -0.646 to 0.558). The area under the receiver operating characteristic curve to predict greater than median percentage of arterial stiffness was 0.892 for CAVI and 0.779 for PWV (P = 0.006). LIMITATION: It is unclear whether arterial fibrosis of the brachial artery evaluated by using CAVI is applicable for arteriosclerosis of other arterial districts, and clinical outcomes were not evaluated in this study. CONCLUSION: CAVI reflects the histological arterial fibrosis of hemodialysis patients and is a useful clinical marker for evaluating arterial stiffness in these patients.

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Effects of 12-month valsartan therapy on glycation and oxidative stress markers in type 2 diabetic subjects with hypertension

Komiya, N., Hirose, H., Saisho, Y., Saito, I. and Itoh, H.

Int Heart J 49 （ 6 ） 681 - 9 2008年11月

ISSN 1349-2365

Although it has been reported that angiotensin II receptor blockers inhibited the formation and accumulation of advanced glycation endproducts (AGEs) in vitro and in vivo, whether they can do so clinically is not clear. We investigated the effects of 12-month valsartan therapy on various markers of inflammation, glycation, and oxidation in type 2 diabetic subjects with hypertension. We started 40 mg/day valsartan treatment in 15 type 2 diabetic patients with hypertension. In 6 patients, the dose of valsartan was increased to 80 mg/day after 6 months and maintained until 12 months. Metabolic parameters including BMI and serum high molecular weight (HMW)-adiponectin, high-sensitivity C-reactive protein (hs-CRP) as an inflammation marker, AGEs, paraoxonase activity, platelet-activating factor (PAF)- acetylhydrolase activity, and urine 8-isoprostane levels were measured at baseline and after 6 and 12 months of treatment. Urine microalbumin level and carotid artery intima-media thickness (IMT) were also measured. Even after valsartan therapy, the blood pressure levels of the patients were not decreased significantly. Serum AGEs and urine 8-isoprostane levels decreased at both 6 and 12 months (P < 0.05 for both), although other metabolic and oxidative markers were unchanged. Though urine microalbumin levels tended to be decreased after 6 and 12 months of valsartan treatment, the changes were not significant. Mean IMT at 12 months was not changed from the baseline value. In conclusion, the findings suggest that treatment with valsartan, even at a low dose, may ameliorate some glycation and oxidative stress markers independently of an effect on blood pressure in hypertensive type 2 diabetic subjects.

The short treatment with the angiotensin receptor blocker candesartan surveyed by telemedicine (STAR CAST) study: rationale and study design

Sasamura, H., Nakaya, H., Julius, S., Takebayashi, T., Sato, Y., Uno, H., Takeuchi, M., Ishiguro, K., Murakami, M., Ryuzaki, M. and Itoh, H.

Hypertens Res 31 （ 10 ） 1843 - 9 2008年10月

ISSN 0916-9636

Previous studies have shown that transient treatment of animal models of hypertension with an angiotensin receptor blocker (ARB) causes a sustained decrease in blood pressure values that persists even after the drug treatment is discontinued (J Am Soc Nephrol 12: 659-666, 2001; Nephron 91: 710-718, 2002; Hypertens Res 30: 63-75, 2007). These results have been shown to be clinically relevant by the recent TROPHY study (N Engl J Med 354: 1685-1697, 2006). We have recently found that transient treatment with an ARB may also cause regression of established hypertension in hypertensive rats (J Am Soc Nephrol 18: 157A, 2007). The Short Treatment with the Angiotensin Receptor Blocker Candesartan Surveyed by Telemedicine (STAR CAST) study is a prospective, randomized, open, blinded end-point study in patients aged 30-59 with a positive family history of hypertension that will be conducted in several centers in Japan. The aim of the study is to evaluate the antihypertensive drug withdrawal success rate, the median duration of drug withdrawal, and the changes in home and office blood pressure values in patients with mild hypertension after tapering and withdrawal of antihypertensive treatment following treatment for 1 year with the ARB candesartan or the calcium channel blocker (CCB) nifedipine slow-release. A unique feature of this study is the use of a home blood pressure monitoring telemedicine system (i-TECHO) to allow frequent evaluation of the changes in blood pressure in the trial patients. This study will be the first clinical study to examine if regression from stage 1 (mild) hypertension to prehypertension (high-normal blood pressure) is possible using an ARB or CCB.

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伊藤 裕

論文 - 伊藤 裕

伊藤　裕

論文 - 伊藤　裕