Yumi Furuno

Severe dyslipidaemia, atherosclerosis, and sudden cardiac death in mice lacking all NO synthases fed a high-fat diet

AIMS The precise role of the nitric oxide synthase (NOS) system in lipid metabolism remains to be elucidated. We addressed this point in mice that we have recently developed and that lack all three NOS isoforms. METHODS AND RESULTS Wild-type (WT), singly, doubly, and triply NOS(-/-) mice were fed either a regular or high-cholesterol diet for 3-5 months. The high-cholesterol diet significantly increased serum low-density lipoprotein (LDL) cholesterol levels in all the genotypes when compared with the regular diet. Importantly, when compared with the WT genotype, the serum LDL cholesterol levels in the high-cholesterol diet were significantly and markedly elevated only in the triply NOS(-/-) genotype, but not in any singly or doubly NOS(-/-) genotypes, and this was associated with remarkable atherosclerosis and sudden cardiac death, which occurred mainly in the 4-5 months after the high-cholesterol diet. Finally, hepatic LDL receptor expression was markedly reduced only in the triply NOS(-/-) genotype, accounting for the diet-induced dyslipidaemia in the genotype. CONCLUSION These results provide the first direct evidence that complete disruption of all NOS genes causes severe dyslipidaemia, atherosclerosis, and sudden cardiac death in response to a high-fat diet in mice in vivo through the down-regulation of the hepatic LDL receptor, demonstrating the critical role of the whole endogenous NOS system in maintaining lipid homeostasis.

Dual effects of nobiletin, a citrus polymethoxy flavone, on catecholamine secretion in cultured bovine adrenal medullary cells.

J. Neurochem. (2010) 114, 1030–1038.

Crucial vasculoprotective role of the whole nitric oxide synthase system in vascular lesion formation in mice: Involvement of bone marrow-derived cells.

Although all three nitric oxide (NO) synthases (nNOS, iNOS, and eNOS) are expressed in injured arteries, it remains to be elucidated the role of the NOSs in their entirety in the vascular lesion formation. We addressed this issue in mice deficient in all NOS genes. Vascular injury was induced by permanent ligation of a unilateral carotid artery in wild-type (WT), singly, and triply NOS(-/-) mice. Two weeks after the procedure, constrictive vascular remodeling and neointimal formation were recognized in the ligated arteries. While constrictive remodeling was noted in the nNOS(-/-) and iNOS(-/-) genotypes, it was most accelerated in the n/i/eNOS(-/-) genotype. While neointimal formation was evident in the eNOS(-/-) and nNOS(-/-) genotypes, it was also most aggravated in the n/i/eNOS(-/-) genotype. Those lesions were reversed by long-term treatment with isosorbide dinitrate, a NO donor. Finally, we examined the involvement of bone marrow-derived cells in the vascular lesion formation. Bone marrow from the WT, singly, or triply NOS(-/-) mice was transplanted into the WT mice, and then the carotid ligation was performed. Intriguingly, constrictive remodeling and neointimal formation were both similarly most exacerbated in the case of the n/i/eNOS(-/-) bone marrow transplantation. These results indicate that the complete disruption of all the NOS genes causes markedly accelerated vascular lesion formation caused by blood flow disruption in mice in vivo, demonstrating the crucial vasculoprotective role of the whole endogenous NOS system. Our findings also suggest that the NOS system in bone marrow-derived cells may be involved in this vasculoprotective mechanism.

Fluvastatin attenuates IGF-1-induced ERK1/2 activation and cell proliferation by mevalonic acid depletion in human mesangial cells

AIMS Insulin-like growth factor (IGF)-1 is a major mitogenic growth factor for mesangial cells (MCs). Statins slow the progression of chronic kidney disease by affecting inflammatory cell signaling pathways, in addition to improving lipid profile, however, no studies have investigated the effects of fluvastatin on mitogen-activated protein (MAP) kinase activity or MC proliferation in kidney cells. We investigated the effects of fluvastatin on IGF-1-induced activation of intracellular signal pathways and MC proliferation, and examined the inhibitory mechanisms of fluvastatin. MAIN METHODS Western blotting and cell proliferation assay were used. KEY FINDINGS IGF-1 induced phosphorylation of extracellular-related kinase (ERK)1/2, MAP or ERK kinase (MEK)1/2, and Akt, expression of cyclin D1, and MC proliferation in cultured human MCs. Fluvastatin or PD98059, an MEK1 inhibitor, completely abolished IGF-1-induced MEK1/2 and ERK1/2 phosphorylation and MC proliferation, whereas inhibition of Akt had no effect on MC proliferation. Mevalonic acid prevented fluvastatin inhibition of IGF-1-induced MEK1/2 and ERK1/2 phosphorylation, cyclin D1 expression, and MC proliferation. SIGNIFICANCE Fluvastatin inhibits IGF-1-induced activation of the MAP kinase pathway and MC proliferation by mevalonic acid depletion, and might have renoprotective effects by inhibiting IGF-1-mediated MC proliferation.

Renoprotective effects of telmisartan in patients with advanced chronic kidney disease.

BACKGROUND Angiotensin II receptor blockers (ARBs) provide renoprotective effects in patients with mild-to-moderate chronic kidney disease (CKD). However, there have been few reports regarding whether ARBs show clinical efficacy and safety in patients with advanced CKD. METHODS Seventy-two hypertensive patients with Stages 3 - 4 CKD receiving no ARBs were enrolled in this study and observed up to 48 months. Telmisartan was added to conventional antihypertensive agents (n = 36, mean estimated glomerular filtration ratio [eGFR] 19.7 ml/min/1.73 m2) whilst the remaining control patients were not treated with ARBs (n = 36, mean eGFR 19.2 ml/min/1.73 m2). Urinary protein excretion, kidney function, and the occurrence of end-stage renal disease requiring renal replacement therapy, hyperkalemia, and death were analyzed. RESULTS Baseline characteristics of each group were similar. During the observation period, the blood pressures of each group decreased at similar rates. In the telmisartan group, 17 patients (47.2%) were introduced to renal replacement therapy, as compared with 31 patients (86.1%) in the control group (relative risk 0.55, 95% confidence interval 0.19 - 0.92, p < 0.05). Telmisartan significantly reduced proteinuria levels (from 3.47 +/- 3.00 to 2.41 +/- 2.46 g/g . creatinine, p < 0.05) and was associated with a reduction of 49.6% in the decline rate of eGFR. The incidence of major adverse events in both groups was similar. CONCLUSIONS The addition of telmisartan to conventional antihypertensive therapy is associated with significant improvement in kidney outcome without increased incidence of adverse effects, even in patients with advanced CKD.

Development of an experimentally useful model of acute myocardial infarction: 2/3 nephrectomized triple nitric oxide synthases-deficient mouse

We investigated the effect of subtotal nephrectomy on the incidence of acute myocardial infarction (AMI) in mice deficient in all three nitric oxide synthases (NOSs). Two-thirds nephrectomy (NX) was performed on male triple NOSs(-/-) mice. The 2/3NX caused sudden cardiac death due to AMI in the triple NOSs(-/-) mice as early as 4months after the surgery. The 2/3NX triple NOSs(-/-) mice exhibited electrocardiographic ST-segment elevation, reduced heart rate variability, echocardiographic regional wall motion abnormality, and accelerated coronary arteriosclerotic lesion formation. Cardiovascular risk factors (hypertension, hypercholesterolemia, and hyperglycemia), an increased number of circulating bone marrow-derived vascular smooth muscle cell (VSMC) progenitor cells (a pro-arteriosclerotic factor), and cardiac up-regulation of stromal cell-derived factor (SDF)-1α (a chemotactic factor of the progenitor cells) were noted in the 2/3NX triple NOSs(-/-) mice and were associated with significant increases in plasma angiotensin II levels (a marker of renin-angiotensin system activation) and urinary 8-isoprostane levels (a marker of oxidative stress). Importantly, combined treatment with a clinical dosage of an angiotensin II type 1 receptor blocker, irbesartan, and a calcium channel antagonist, amlodipine, markedly prevented coronary arteriosclerotic lesion formation and the incidence of AMI and improved the prognosis of those mice, along with ameliorating all those pro-arteriosclerotic parameters. The 2/3NX triple NOSs(-/-) mouse is a new experimentally useful model of AMI. Renin-angiotensin system activation, oxidative stress, cardiovascular risk factors, and SDF-1α-induced recruitment of bone marrow-derived VSMC progenitor cells appear to be involved in the pathogenesis of AMI in this model.

Impacts of icodextrin on integrin-mediated wound healing of peritoneal mesothelial cells

AIMS Exposure to glucose and its metabolites in peritoneal dialysis fluid (PDF) results in structural alterations of the peritoneal membrane. Icodextrin-containing PDF eliminates glucose and reduces deterioration of peritoneal membrane function, but direct effects of icodextrin molecules on peritoneal mesothelial cells have yet to be elucidated. We compared the impacts of icodextrin itself with those of glucose under PDF-free conditions on wound healing processes of injured mesothelial cell monolayers, focusing on integrin-mediated cell adhesion mechanisms. MAIN METHODS Regeneration processes of the peritoneal mesothelial cell monolayer were investigated employing an in vitro wound healing assay of cultured rat peritoneal mesothelial cells treated with icodextrin powder- or glucose-dissolved culture medium without PDF, as well as icodextrin- or glucose-containing PDF. The effects of icodextrin on integrin-mediated cell adhesions were examined by immunocytochemistry and Western blotting against focal adhesion kinase (FAK). KEY FINDINGS Cell migration over fibronectin was inhibited in conventional glucose-containing PDF, while icodextrin-containing PDF exerted no significant inhibitory effects. Culture medium containing 1.5% glucose without PDF also inhibited wound healing of mesothelial cells, while 7.5% icodextrin-dissolved culture medium without PDF had no inhibitory effects. Glucose suppressed cell motility by inhibiting tyrosine phosphorylation of FAK, formation of focal adhesions, and cell spreading, while icodextrin had no effects on any of these mesothelial cell functions. SIGNIFICANCE Our results demonstrate icodextrin to have no adverse effects on wound healing processes of peritoneal mesothelial cells. Preservation of integrin-mediated cell adhesion might be one of the molecular mechanisms accounting for the superior biocompatibility of icodextrin-containing PDF.

An integrin-activating peptide, PHSRN, ameliorates inhibitory effects of conventional peritoneal dialysis fluids on peritoneal wound healing

BACKGROUND Bioincompatible peritoneal dialysis fluids (PDFs) cause pathological changes in the peritoneal membrane, related to membrane dysfunction and progressive peritoneal fibrosis. We investigated the effects of Pro-His-Ser-Arg-Asn (PHSRN) peptide, one of the fibronectin cell-binding domains that activates integrins and reinforces wound healing, on peritoneal remodelling in a rat peritoneal injury model undergoing peritoneal dialysis. METHODS The peritoneal mesothelial monolayer was removed by a stripping procedure in rats receiving conventional high glucose-containing PDF supplemented with or without PHSRN or control His-Ser-Pro-Asn-Hrg (HSPNR) peptides. Effects of PHSRN on cell motility and signalling molecules were examined in cultured rat peritoneal mesothelial cells (RPMCs) and normal rat kidney fibroblasts (NRKs). RESULTS The cytokeratin- and HBME-1-positive mesothelial cell monolayer was selectively removed by the procedure. By day 6, HBME-1-positive cells had regenerated to 53.3 +/- 6.5% of the peritoneal surface in the control group. Regeneration of the mesothelial layer was delayed in the PDF group (35.2 +/- 10.2%, P < 0.05), but PHSRN reversed the effects of PDF (51.7 +/- 9.6%, P < 0.05). PDF treatment increased thickening of granulomatous submesothelial tissue and numbers of ED1-, CD31- and alpha-smooth muscle actin-positive cells, but PHSRN ameliorated these effects. HSPNR had no effects on mesothelial regeneration or peritoneal wound healing. PHSRN, but not HSPNR, recovered glucose-induced inhibition of cell motility and phosphorylation of focal adhesion kinase and its downstream p130(Cas) in RPMCs and NRKs. CONCLUSIONS These results suggest that PHSRN has beneficial effects on peritoneal regeneration by reducing the inhibitory effects of conventional PDF on integrin-mediated wound healing.

A Case Report of Steroid‐resistant Antineutrophil Cytoplasmic Antibody‐related Vasculitis Successfully Treated by Mizoribine in a Hemodialysis Patient

Abstract:  Mizoribine (MZR) has shown to be effective against antineutrophil cytoplasmic antibody (ANCA)‐related vasculitis; however, no reports have described the successful treatment of steroid‐resistant ANCA‐related vasculitis with MZR in patients with renal insufficiency requiring hemodialysis. We herein report the case of a 39‐year‐old man undergoing hemodialysis in whom MZR successfully lowered the myeloperoxidase (MPO)–ANCA titer accompanied by remission of interstitial pneumonia, together with the pharmacokinetics of MZR. The patient developed severe renal insufficiency and interstitial pneumonia, and was started on hemodialysis. Although prednisolone was administered followed by azathioprine, the MPO–ANCA level and interstitial pneumonia showed insufficient improvement. Azathioprine was replaced by MZR and the administered dose of MZR was determined by measuring serum concentrations of MZR at the start of the dialysis session; this was because we confirmed that MZR could only be removed via dialysis, and that the serum concentration of MZR was maintained until the next dialysis session. The maintenance dose was finally set at MZR 75 mg after each dialysis. Subsequently, the ANCA titer decreased and interstitial pneumonia resolved without any MZR‐related side effects. This case demonstrates that MZR is safe and effective, even in patients with steroid‐resistant ANCA‐related vasculitis undergoing hemodialysis, and can be monitored by measuring serum concentrations of MZR.

Monocarboxylate Transporter-1 Mediates the Protective Effects of Neutral-pH Bicarbonate/Lactate-Buffered Peritoneal Dialysis Fluid on Cell Viability and Apoptosis

We investigated the effects of bicarbonate/lactate‐buffered peritoneal dialysis fluid (B/L‐PDF) and lactate‐buffered PDF (L‐PDF) on cell viability and apoptosis, focusing on monocarboxylate transporters (MCTs). MCT‐1 transports lactate into cells. Cell viability and apoptosis of human peritoneal mesothelial cells (HPMCs) were examined by water‐soluble tetrazolium salt‐1 and TUNEL assays, respectively. The relative number of viable HPMCs was significantly decreased by L‐PDF at 48 h (8.8 ± 0.4%) compared with cells cultured in M199, but not by B/L‐PDF (66.7 ± 1.1%). Apoptosis was markedly induced by L‐PDF at 48 h (69.3 ± 16.2%), but not by B/L‐PDF (2.6 ± 0.3%). Knockdown of MCT‐1 by small interfering RNA (siRNA) attenuated the L‐PDF‐induced reduction of viable cells and increased apoptosis compared with control siRNA, but MCT‐4 knockdown had no effect. B/L‐PDF had lesser effects on cell viability and apoptosis of HPMCs compared with L‐PDF. These results suggest that B/L‐PDF biocompatibility occurs by avoiding the induction of apoptosis in HPMCs.