Administration of angiotensin II to rats decreases renal expression of klotho, an aging-related gene, and also causes abnormal iron deposition in renal cells. Here we have examined the e¡ects of iron overload and iron chelation on renal expression of klotho in untreated rats and rats treated with angiotensin II. Administration of iron^dextran caused a downregulation of klotho expression, and iron chelation suppressed the angiotensin II-induced downregulation of this gene. In addition, a free radical scavenger (T-0970), which e¡ectively decreased plasma levels of 8-epi-prostaglandin F 2K (8-epi-PGF 2K ), suppressed angiotensin II-induced downregulation of klotho. Collectively, these ¢ndings suggest that abnormal iron metabolism and increased oxidative stress are involved in the mechanism of angiotensin II-mediated modulation of klotho expression.

Retroperitoneal fibrosis, inflammatory aortic aneurysm, and pericardial and mediastinal fibrosis are characterized by infiltration of immuno-inflammatory cells and deposition of thickened fibrous tissues. Several recent studies suggested that an immunoglobulin-G4 (IgG4)-related immunological mechanism may play a role in these diseases. By searching the clinical database of patients admitted to our department between 2000 and 2010, we summarized the clinical data of 11 patients who were diagnosed to have these disorders. The diagnoses were idiopathic retroperitoneal fibrosis (8 cases), mediastinal and/or pericardial fibrosis (4 cases), inflammatory abdominal aneurysm (2 cases), and inflammatory coronary periarteritis (1 case). Hypertension, diabetes, and dyslipidemia were found in 45%, 36%, and 55%, respectively, in these patients, and they were all either current or former smokers. Two patients with pericardial involvement showed a rushed clinical course, resulting in in-hospital death. Serum levels of IgG were elevated in 67%, and soluble interleukin-2 receptor was elevated in 75%, when measured. Immunohistochemical analysis showed marked infiltration of IgG4-positive plasma cells in the pericardium in patients who died of constrictive pericarditis. Our data support the notion that immune-inflammatory mechanism, which might be IgG4-related sometimes, may play a role in idiopathic retroperitoneal fibrosis, inflammatory aortic aneurysm, and mediastinal/pericardial fibrosis, although clinical course may differ substantially.

Background-Abnormal iron deposition may cause oxidant-induced damage in various organs. We have previously reported that continuous administration of angiotensin II to rats results in an overt iron deposition in the renal tubular epithelial cells, which may have a role in angiotensin II-induced renal damage. In the present study, we investigated the role of iron in the development of cardiac injury induced by angiotensin II. Methods and Results-Angiotensin II was continuously infused to rats at a dose of 0.7 mg/kg per day for 7 consecutive days. No iron deposits were observed in the hearts of untreated rats, whereas iron deposition was seen in the cells in the subepicardial and granulation regions after angiotensin II infusion. Concomitant administration of deferoxamine, an iron chelator, significantly reduced the extent of cardiac fibrosis, which suggests that iron deposition aggravates the cardiac fibrosis induced by angiotensin II. Iron overload caused by the administration of iron-dextran resulted in an augmentation of cardiac fibrosis and the generation of neointimal cells in the coronary artery in angiotensin II-infused rats. By contrast, neointima was not formed in the cardiac vessels in norepinephrine-infused rats with iron overload. Conclusions-Cardiac iron deposition may be involved in the development of cardiac fibrosis induced by angiotensin II.In addition, iron overload may enhance the formation of neointima under conditions of increased circulating angiotensin II but not catecholamines.

Objective-We have investigated whether long-term administration of angiotensin (Ang) II causes ferritin induction and iron accumulation in the rat aorta, and their possible relation to regulatory effects on gene expression and vascular function in Ang II-infused animals. Methods and Results-Sprague-Dawley rats were given Ang II for 7 days via subcutaneously implanted osmotic minipumps. Ang II infusion caused a Ͼ20-fold increase in ferritin protein expression over control values. Immunohistochemistry showed that Ang II infusion markedly increased the ferritin expression in the aortic endothelial and adventitial cells, with some of the latter being identified as monocytes/macrophages. Prussian blue staining showed that stainable iron was observed in the adventitial layer of aorta from Ang II-infused animals, but not in the endothelial layer. Chelation of iron suppressed aortic induction of ferritin and also the oxidative stress markers, heme oxygenase-1 and 4-hydroxynonenal-modified protein adducts. In addition, iron chelation attenuated Ang II-induced impairment of aortic relaxations in response to acetylcholine and sodium nitroprusside and suppressed upregulation of mRNA levels of monocyte chemoattractant protein-1. Iron chelation also partially attenuated the medial thickening and perivascular fibrosis induced by Ang II infusion for 4 weeks. Conclusion-Ang

Abstract-Abnormal lipid metabolism may play a role in progressive renal failure. We studied whether lipid accumulation occurs and whether lipid deposits are colocalized with transforming growth factor-␤1 (TGF-␤1) in the kidney of angiotensin II-infused animals. Oil red O staining showed marked lipid deposition in the tubular epithelial and vascular wall cells of angiotensin II-treated but not in norepinephrine-treated rats. Histological analyses showed that increased amounts of superoxide and intense TGF-␤1 mRNA expression were present in lipid-positive tubular epithelial cells in angiotensin II-infused animals. Protein expression of sterol regulatory element-binding protein 1 (SREBP-1) and mRNA expression of fatty acid synthase in the kidney were Ϸ3 times and 1.5 times, respectively, higher in angiotensin II-treated rats than in controls. Treatment of angiotensin II-infused animals with an iron chelator, deferoxamine, attenuated the angiotensin II-induced increases in renal expression of SREBP-1 and fatty acid synthase and normalized the lipid content in the renal cortical tissues. Abnormal lipid metabolism may be associated with upregulation of TGF-␤1 expression and aberrant iron homeostasis in the kidneys of angiotensin II-infused animals. Key Words: angiotensin II Ⅲ transforming growth factors Ⅲ lipids P revious studies showed that accumulation of lipids in nonadipose tissues occurs in certain diseased conditions, and that it plays a crucial role in the pathogenesis of tissue damage, 1 a phenomenon referred to as lipotoxicity. 2 For example, lipid deposition in the arterial wall 3,4 is postulated to represent an early event in the development of atherosclerosis. 5 The accumulation of triglycerides (TGs) in cardiomyocytes 6,7 may be associated with contractile dysfunction, and excess TGs in the liver may promote hepatic fibrosis. 8 Lipid accumulation in the kidney may represent features of glomerular and tubulointerstitial damage. 9 We found that long-term administration of angiotensin II (Ang II) to rats caused marked deposition of iron 10 and upregulation of the expression of transforming growth factor-␤1 (TGF-␤1) in renal tubular epithelial cells. 11 We also found that iron chelation attenuated the Ang II-induced upregulation of TGF-␤1 in the kidney, suggesting a possible link between aberrant iron homeostasis and TGF-␤1 upregulation. However, unexpectedly, histological analysis showed that upregulation of TGF-␤1 mRNA and deposition of iron occurred in different tubular cells in most cases. The aims of the present study were to investigate whether accumulation of lipids occurs in the kidney of Ang II-infused animals and to investigate the relationship between lipid accumulation and TGF-␤1 in terms of localization. We also investigated whether Ang II infusion alter the expression of genes that have relation to the lipid metabolism, such as ATP-binding cassette transporter subfamily A-1 (ABCA1), scavenger receptor class B type 1 (SR-B1), sterol regulatory elementbinding protein 1 (SREBP-1), SREBP-2, 3-hydrox...

Due to recent discoveries of novel genes involved in iron metabolism, our understanding of the molecular mechanisms underlying iron metabolism has dramatically increased. We have previously shown that the administration of angiotensin II alters iron homeostasis in the rat kidney, which may in turn aggravate angio-

We have previously shown that abnormal iron metabolism might be one underlying mechanism of the renal damage observed in the angiotensin II-infused rat. Transforming growth factor-1 (TGF-1) is known to play a crucial role in the development of renal damage induced by activation of the renin-angiotensin-aldosterone system. The purpose of the present study was to examine the effects of an iron chelator and a free creases the renal expression of TGF-β in animal models of glomerulosclerosis (2, 3), hypertension (4), and diabetes (5), and this decrease is accompanied by a decrease in urinary excretion of protein. In addition, administration of exogenous angiotensin II to rats has been shown to induce renal expression of TGF-β1 (6). The idea that TGF-β plays a crucial role in the development of renal damage was supported by the recent findings that anti-TGF-β antibody ameliorates renal damage in some animal models (7,8); therefore, induc-

Long-term administration of angiotensin II causes myocardial loss and cardiac fibrosis. We previously found iron deposition in the heart of the angiotensin II-infused rat, which may promote angiotensin II-induced cardiac damage. In the present study, we have investigated whether an iron chelator (deferoxamine) and a free radical scavenger (T-0970) affect the angiotensin II-induced upregulation of transforming growth factor-beta1 (TGF-beta1). Angiotensin II infusion for 7 days caused a robust increase in TGF-beta1 mRNA expression in vascular smooth muscle cells, myofibroblast-like cells, and migrated monocytes/macrophages. T-0970 and deferoxamine suppressed the upregulation of TGF-beta1 mRNA and reduced the extent of cardiac fibrosis in the heart of rats treated with angiotensin II. These agents blocked the angiotensin II-induced upregulation of heme oxygenase-1, a potent oxidative and cellular stress-responsive gene, but they did not significantly affect systolic blood pressure or plasma levels of aldosterone. In addition, T-0970 and deferoxamine suppressed the angiotensin II-induced upregulation of monocyte chemoattractant protein-1 in the heart. These results collectively suggest that iron and the iron-mediated generation of reactive oxygen species may contribute to angiotensin II-induced upregulation of profibrotic and proinflammatory genes, such as TGF-beta1 and monocyte chemoattractant protein-1.