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Enyu Imai

Publications and source records attributed to Enyu Imai.

At least 55 records · Page 3Linked to original sources
PubMed2004

Gene therapy in renal diseases.

Kidney-targeted gene therapy could be an ideal treatment for renal diseases since the therapeutic molecule is limited in the kidney and the systemic effect may be minimized. The technical development of the gene delivery to kidney and the identification of the responsive gene for a particular disease encourage the challenge to hereditary diseases. Collagen type IV reassembling was reported to be succeeded in Alport syndrome model by introduction of exogenous COL4A5 gene. Many gene therapies are evaluated in various glomerulonephritis models and unilateral ureteral obstruction (UUO) model, and favorable results are accumulated. Transplant kidney is an ideal target for gene therapy, by which ischemia reperfusion, acute rejection and chronic allograft nephropathy can be treated. The importation of the novel technology, for example hybrid stem cell-gene therapy could promote the gene therapy of renal diseases toward clinical application.

Animals↗
PubMed2004

Perspectives for gene therapy in renal diseases.

Somatic cell gene therapy has made considerable progress last five years and has shown clear success in some clinical trials. In the field of nephrology, both the elucidation of pathophysiology of renal diseases and the development of gene transfer technique have become driving force for new therapy of incurable renal diseases, such as Alport syndrome and polycystic kidney disease. Gene therapy of renal cancer, although its application is limited to advanced cancer, is the front-runner of clinical application. Erythropoietin gene therapy has provided encouraging results for the treatment of anemia in uremic rats and recently progressed to the inducible one in response to hypoxia. Gene therapy for glomerulonephritis and renal fibrosis showed prominent impact on experimental models, although the safety must be confirmed for prolonged treatment. Transplant kidney is an ideal material for gene modification and induction of tolerance in the transplant kidney is an attractive challenge. Emerging techniques are becoming available such as stem cell technology and messenger RNA silencing strategies. We believe that the future of gene therapy research is exciting and promising and it holds an enormous potential for clinical application.

Adenoviridae↗
PubMed2004

Intravenous immunoglobulin (IVIg) therapy in MPO-ANCA related polyangiitis with rapidly progressive glomerulonephritis in Japan.

For 30 myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA) related rapidly progressive glomerulonephritis patients (male 17, female 13, average age of 68 +/- 11.8 years old), intravenous immunoglobulin (IVIg) (400 mg/kg/day) was administered for 5 consecutive days before or along with conventional immunosuppressive therapy in Japan. Twenty patients were treated with IVIg before the start or newly increase of conventional therapy and evaluated the independent effect of this therapy. In these patients, just after IVIg, significant decrease of CRP from 8.61 +/- 5.77 to 5.47 +/- 4.50 mg/dl (P < 0.001) was noted with improvement of elevated serum creatinine in 12 out of 19 patients (63%). In the analysis of the overall outcome of 30 patients, at 3 months after IVIg and following conventional therapy, no patients showed renal death except 4 for whom hemodialysis had been started before IVIg. At 6 months, renal survival rate were 92% (newly renal death 2 out of 26) and 2 patients died due to cerebral bleeding (survival rate was 93%). No fatal infection was noted. IVIg might be the potent inducible therapy which can be promoted before the beginning of conventional immunosuppressant treatment for relatively aged and lower immunopotent MPO-ANCA patients in Japan.

Adult↗
PubMed2003

Correlation between the Banff 97 classification of renal allograft biopsies and clinical outcome.

The 1997 fourth Banff meeting revised the consensus for describing transplant biopsies. We have conducted a retrospective analysis of biopsies correlated between the Banff 97 classification and clinical outcome. The patients ( n=149), who had a total of 404 biopsy-proven rejections, were assessed and the biopsies taken from these patients were re-examined and classified according to the Banff 97 classification. Morphological changes in the glomeruli (g), interstitium (i), tubules(t), and arterial vessels (v) were scored. Severity of acute rejection was statistically associated with unresponsiveness to anti-rejection treatment ( P<0.0001) and predicted an increased risk of graft failure ( P<0.05). Each quantitative criterion (g, i, t, and v) was also statistically associated with unresponsiveness to anti-rejection treatment. Mean serum creatinine levels were significantly higher in the groups graded Banff 97 type I-III after 1 and 2 years of follow-up. The Banff 97 classification correlated with reversibility of rejection episodes and long-term graft survival.

Biopsy↗
PubMed2003

Induction of glia maturation factor-beta in proximal tubular cells leads to vulnerability to oxidative injury through the p38 pathway and changes in antioxidant enzyme activities.

Proteinuria is an independent risk factor for progression of renal diseases. Glia maturation factor-beta (GMF-beta), a 17-kDa brain-specific protein originally purified as a neurotrophic factor from brain, was induced in renal proximal tubular (PT) cells by proteinuria. To examine the role of GMF-beta in PT cells, we constructed PT cell lines continuously expressing GMF-beta. The PT cells overexpressing GMF-beta acquired susceptibility to cell death upon stimulation with tumor necrosis factor-alpha and angiotensin II, both of which are reported to cause oxidative stress. GMF-beta overexpression also promoted oxidative insults by H2O2, leading to the reorganization of F-actin as well as apoptosis in non-brain cells (not only PT cells, but also NIH 3T3 cells). The measurement of intracellular reactive oxygen species in the GMF-beta-overexpressing cells showed a sustained increase in H2O2 in response to tumor necrosis factor-alpha, angiotensin II, and H2O2 stimuli. The sustained increase in H2O2 was caused by an increase in the activity of the H2O2-producing enzyme copper/zinc-superoxide dismutase, a decrease in the activities of the H2O2-reducing enzymes catalase and glutathione peroxidase, and a depletion of the content of the cellular glutathione peroxidase substrate GSH. The p38 pathway was significantly involved in the sustained oxidative stress to the cells. Taken together, the alteration of the antioxidant enzyme activities, in particular the peroxide-scavenging deficit, underlies the susceptibility to cell death in GMF-beta-overexpressing cells. In conclusion, we suggest that the proteinuria induction of GMF-beta in renal PT cells may play a critical role in the progression of renal diseases by enhancing oxidative injuries.

3T3 Cells↗
PubMed2003

Gene transfer into the liver by plasmid injection into the portal vein combined with electroporation.

BACKGROUND: We investigated the optimum conditions for gene transfer into the liver by injection of plasmid via the portal vein combined with electroporation. METHODS: In anesthetized 7-week-old male Shionogi Wistar rats, a tapered 3Fr. catheter was inserted through a branch of the colonic vein and its tip was secured into the portal vein. After clamping the vessels around the right and caudal lobes of the liver, FITC-oligodeoxynucleotide (ODN), green fluorescence protein (GFP) plasmid, or pCAGGS-luciferase was injected into the right and caudal lobes during electroporation using electric pulses applied to the caudal lobe only. RESULTS: Transfected cells were identified by FITC-ODN and GFP fluorescence, and transfection efficacy was estimated by measurement of luciferase activity. FITC-ODN and GFP were detected in the caudal lobes of the liver. FITC-ODN was particularly present in hepatocytes surrounding the Glisson capsule and central veins, while GFP was detected in only hepatocytes surrounding the Glisson capsule. Luciferase activity in the liver was dependent on the plasmid concentration and voltage of the electric pulse, but independent of the volume of plasmid solution. Luciferase activity was limited in the right lobe, in which plasmid solution was injected but no electroporation was applied. CONCLUSIONS: Our results showed local expression of the induced gene at the electroporation site, suggesting it is potentially useful for liver function support during recovery after extensive liver surgery and for the treatment of chronic and/or diffuse liver diseases.

Animals↗
PubMed2003

Electroporation-mediated ex vivo gene transfer into graft not requiring injection pressure in orthotopic liver transplantation.

BACKGROUND: We investigated optimum conditions for ex vivo gene transfer into liver grafts by plasmid injection via the portal vein combined with electroporation in rat liver transplantation. METHODS: Anesthetized 9-week-old male Shionogi-Wistar rats were used as donors and recipients. After harvest of the liver graft from the donor rat, a tapered 3Fr. catheter was inserted into the portal vein of the liver graft ex vivo. After clamping the afferent vessels around the right and caudal liver lobes, pCAGGS-luciferase, which was diluted with one of several osmotic pressure solutions, or pCAGGS-green fluorescence protein (GFP) plasmid was injected into these lobes to keep the efferent vessels patent. Electrical pulses were applied to the liver graft during cold preservation in lactated Ringer's solution, University of Wisconsin solution, and histidine-tryptophan-ketoglutarate solution. RESULTS: Transfection efficacy was estimated by measurement of luciferase activity. Luciferase activity in the liver was dependent on both the voltage and electric current of the electrical pulse, and also on the type of preservation solution and plasmid osmotic pressure. Luciferase activity was noted only in plasmid-injected lobes of the liver graft. GFP-transfected cells were identified by GFP fluorescence. GFP was observed predominantly in perivascular cells, including hepatocytes. CONCLUSIONS: We have demonstrated successful ex vivo gene transfection into liver grafts without injection pressure by using a non-viral method.

Animals↗
PubMed2003

Carbonic adsorbent AST-120 retards progression of renal failure by additive effect with ACEI and protein restriction diet.

BACKGROUND: In order to slow the progression of chronic renal failure (CRF), a multimodal approach should be applied if the efficacy is proved. Although compelling evidence of a beneficial effect exists for the use of angiotensin-converting enzyme inhibitors (ACEIs) and low-protein diets, there is little evidence on whether carbon adsorbent has an effect on retardation of the progression of CRF. METHODS: In experiment 1, we examined whether the oral carbon adsorbent, AST-120, conferred an additive effect with captopril and an 80% restriction diet on the survival rate of 3/4 nephrectomized rats (3/4 NX). The 3/4 NX rats were divided into three groups (C, control, n = 7; AD, captopril (an ACEI) +80% restriction diet (RD), n = 8; and ADK, ACEI + RD + AST-120, n = 8) and survival was observed for 72 weeks. In experiment 2, 3/4 NX rats were divided into four groups (C, control, n = 4; D, 80% restriction diet, n = 4; AD, temocapril + RD, n = 9; and ADK, temocapril + RD + AST-120, n = 9) for the examination of renal function, blood pressure, hematocrit (Ht), serum albumin, and proteinuria every month. We analyzed morphological changes in the kidney at 48 weeks. RESULTS: In experiment 1, ADK did not improve the survival rate compared with AD, although ADK prolonged the survival significantly compared with C (C vs AD, P = 0.24; C vs ADK, P = 0.0007; AD vs ADK, P = 0.073). In experiment 2, renal function and proteinuria were significantly ameliorated in the ADK group compared with AD at 48 weeks. Concomitantly with the preservation of renal function, pathological indices, including the glomerular sclerosis index and the interstitial fibrosis index, were significantly improved in ADK compared with AD. In the ADK group, Ht and serum albumin did not change over the 48 weeks. CONCLUSIONS: Administration of AST-120 in addition to an ACEI and a restriction diet preserves renal function independently of blood pressure control, angiotensin II inhibition, and protein restriction in 3/4 NX rats at 48 weeks, but does not improve the survival significantly.

Adsorption↗
PubMed2003

Tranexamic acid-induced visual impairment in a hemodialysis patient.

We report a case of overdosage of tranexamic acid (TNA), which was suggested as the cause of visual impairment in a 56-year-old man. He had been undergoing chronic hemodialysis for 1 year, following 10 years of peritoneal dialysis. He had been hospitalized for an emergency operation for a bleeding ulcer of the stomach and duodenum. After the operation, he experienced a gradual loss of sight over about 1 week, although his general condition was good. He received intravenous injections of TNA as a hemostat during hospitalization for the operation. Two weeks after the operation he became blind. Retinography was flat and his visual field had become narrowed. On fluorescein angiography, microgranular hyperfluorescence, which indicated malfunction of the pigmented layer of the retina, was observed. No abnormality of the brain or the optic nerve was shown by magnetic resonance imaging. Concentrations of vitamins and trace minerals in the blood were within the normal ranges. Administration of vitamins A and B(12) did not improve his sight. However, discontinuation of TNA rapidly restored his sight, within a few days. He had received TNA once before because of bleeding ulcer, and his sight had been impaired at that time. Based on the repeated episodes, it was strongly suggested that an overdose of TNA in this dialysis patient caused the sight disturbance. Because TNA is metabolized by the kidney, caution is necessary when prescribing TNA for patients with renal failure.

Angiography↗
PubMed2003

Antisense oligonucleotides against thrombospondin-1 inhibit activation of tgf-beta in fibrotic renal disease in the rat in vivo.

Specific treatment of chronic progressive renal disease is very limited. TGF-beta, considered as the major cytokine causing tissue scarring, must be activated extracellularly before it can bind to its receptors. Thrombospondin-1 (TSP1) has been identified as an activator of latent TGF-beta in in vitro systems and in pancreas and lung homeostasis in mouse pups in vivo, but whether this is also true in inflammatory fibrotic disease is unknown. We examined a rat model of mesangial proliferative glomerulonephritis, where TGF-beta has been demonstrated to mediate renal fibrosis. In this study, antisense phosphorothioate oligonucleotides against TSP1 were successfully transferred into almost all glomeruli of perfused diseased kidneys and markedly inhibited de novo synthesis of TSP1. This effect was accompanied by decreased activation but not expression of TGF-beta and by the inhibition of the TGF-beta-dependent smad-signaling pathway, as well as transcription of TGF-beta target genes such as EDA-fibronectin, resulting in a markedly suppressed accumulation of extracellular matrix. In sharp contrast, neither glomerular cell proliferation nor influx of macrophages was affected by this therapy in experimental mesangial proliferative glomerulonephritis. These results demonstrate that TSP1 is the major endogenous activator of TGF-beta in experimental inflammatory kidney disease.

Animals↗
PubMed2003

Therapeutic effect of all-trans retinoic acid on rats with anti-GBM antibody glomerulonephritis.

BACKGROUND: All-trans retinoic acid (ATRA) has antiproliferative and anti-inflammatory effects and is currently used in the treatment of leukemia and dermatologic diseases. We tested the therapeutic potential of ATRA on anti-glomerular basement membrane (GBM) glomerulonephritis rats. METHODS: Glomerulonephritis was induced in male Wistar-Kyoto rats on day 0 by an intravenous injection of antirat GBM antibody. On day 14 after the induction of anti-GBM glomerulonephritis, some rats were sacrificed (N = 5). Another 10 rats were divided into two groups: the vehicle group (N = 5) and the ATRA treated group (N = 5). ATRA was orally administrated from day 14 to day 27 after disease induction. Blood pressure, body weight, urinary protein excretion, and blood chemistry was determined on days 1, 14, 21, and 27. Kidney samples were obtained on day 28. The kidneys were examined with periodic acid-Schiff staining (PAS) and immunohistochemistry using antibodies against the proliferative cell nuclear antigen (PCNA), rat monocyte and macrophage (ED-1), and alpha-smooth muscle actin (alpha-SMA). Glomerular RNA was extracted from isolated glomeruli, and reverse transcription (RT) followed by polymerase chain reaction (PCR) was performed. RESULTS: ATRA administration produced a 55% reduction of proteinuria in glomerulonephritis rats. Light microscopic analysis revealed severe necrosis/crescent formation (>50% of the glomerulus) affecting 34% of glomeruli in vehicle rats, whereas ATRA treatment reduced the glomeruli showing severe change to 14%. ATRA also significantly reduced PCNA-positive cells, ED-1-positive cells and alpha-SMA-positive area in the glomeruli. RT-PCR analyses revealed that a wide variety of genes including inflammation related [tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and CCAAT enhancer-binding protein delta (C/EBPdelta)], cell proliferation-related [platelet-derived growth factor (PDGF)] and fibrosis-related [transforming growth factor-beta1 (TGF-beta1), type I collagen, and alpha-SMA) genes were suppressed in the glomeruli of ATRA-treated rats. CONCLUSION: ATRA administration significantly reduced severe necrosis/crescent formation and urinary protein excretion in glomerulonephritis rats. Suppression of a wide variety of gene expression may partly explain the mechanism of ATRA's antiproliferative and anti-inflammatory effects. These data suggest a novel therapeutic application of ATRA toward glomerulonephritis.

Animals↗
PubMed2003

Specific inhibition of Egr-1 prevents mesangial cell hypercellularity in experimental nephritis.

BACKGROUND: Mesangial cell proliferation is a frequent finding in glomerulonephritis. In cultured mesangial cells, we demonstrated that inhibition of the zinc finger transcription factor, early growth response gene-1 (Egr-1), by specific antisense oligonucleotides (AS ODN) blocks mesangial cell proliferation. Therefore, we here investigated the effect of Egr-1 inhibition on the course of an experimental mesangioproliferative glomerulonephritis in vivo. METHODS: On day 3 after induction of anti-Thy-1.1 nephritis, specific glomerular oligonucleotide transfer was achieved by injection of an oligonucleotide/hemagglutinating virus of Japan/liposome mixture into the left renal artery. The right kidney was left untreated. RESULTS: Induction of nephritis led to a sixfold induction of Egr-1 protein on day 6 of disease. This increase in Egr-1 expression was reduced by 48% in the left kidney by transfer of specific AS ODN. In parallel, the increases in glomerular cellularity, number of mitoses, and glomerular tuft area observed in day 6 nephritic animals were inhibited in the left kidney by 60%, 53%, and 50%, respectively. Changes in the right kidney were not significantly influenced. Likewise, control oligonucleotides showed no effect. Finally, the expression of platelet-derived growth factor-B (PDGF-B), a known target gene of Egr-1, was repressed by transfer of specific AS ODN against Egr-1. CONCLUSION: We conclude that the transcription factor Egr-1 plays a critical role for mesangial cell proliferation in vivo. Interfering with the induction of Egr-1 or with its target genes could give rise to novel therapeutic principles in mesangioproliferative glomerulonephritis.

Animals↗
PubMed2003

Effects of the oral adsorbent AST-120 on tryptophan metabolism in uremic patients.

BACKGROUND: Tryptophan (TRP), an essential amino acid, is bound mostly to albumin in plasma. However, it is reported that binding is inhibited by indoles that accumulate in uremic plasma. This may be responsible for the malnutrition observed in uremic patients. AST-120, an oral adsorbent of uremic toxins, can reduce concentrations of indoxyl sulfate (IS), the most abundant indolic metabolite in uremic plasma. We therefore investigated whether AST-120 recovers TRP binding to plasma proteins and improves the nutritional state of uremic patients. METHODS: The in vitro binding ratio of TRP to bovine serum albumin (BSA) was measured in the presence of IS by the equilibrium dialysis technique. In addition, five predialysis patients with chronic renal failure (CRF) were administered AST-120 for 2 months. Plasma concentrations of total TRP, IS, and free TRP were measured in five healthy volunteers (normal [N] group) and five patients with CRF before and after 2 weeks of AST-120 therapy (6 g/d). Their nutritional statuses also were compared before and after 2 months of AST-120 administration. RESULTS: IS inhibited in vitro binding of TRP to BSA in a dose-dependent manner. Total TRP concentrations and protein-binding ratios in patients with CRF (0.90 +/- 0.08 mg/dL and 68.7% +/- 6.8%, respectively) were significantly lower than those in the N group (2.45 +/- 0.45 mg/dL and 92.0% +/- 1.4%, respectively). However, a 2-week administration of AST-120 significantly reduced IS levels from 1.79 +/- 1.01 to 1.15 +/- 0.85 mg/dL (N group, 0.06 +/- 0.01 mg/dL), increased total TRP levels (1.16 +/- 0.18 mg/dL), and improved the TRP plasma protein-binding ratio to 83.1% +/- 3.8%, whereas total protein and albumin levels remained unchanged. After 2 months of AST-120 administration, serum albumin and transferrin levels increased significantly. CONCLUSION: AST-120 improves nutritional state, at least partly through correcting impaired TRP metabolism, in patients with CRF.

Administration, Oral↗
PubMed2003

Retinoids regulate the repairing process of the podocytes in puromycin aminonucleoside-induced nephrotic rats.

The foot processes forming the slit diaphragm are disrupted in diseases associated with proteinuria. Although they are often repairable, regulators for the repairing process remain unknown. By extrapolating from the fact that vitamin A is essential for the nephrogenesis, this study examined whether or not injured podocytes in the middle of the repairing process require retinaldehyde dehydrogenase type 2 (RALDH2), one of the key enzymes to produce all-trans-retinoic acid (ATRA). RALDH2 was dramatically upregulated in podocytes of puromycin aminonucleoside-induced nephrosis (PAN nephrosis) rats. On day 5 of PAN nephrosis, RALDH2 showed the remarkable induction, whereas glomerular expression levels of nephrin and midkine, one of the ATRA target genes, were downregulated. Daily administration of ATRA ameliorated proteinuria, which was accompanied by the improvement in the effacement of the foot processes and by the induction of nephrin and midkine. In contrast, recovery from PAN nephrosis was delayed in rats fed with a vitamin A-deficient diet. Consistently, the promoter region of human nephrin gene (NPHS1) contained three putative retinoic acid response elements (RARE) and showed the enhancer activity in response to ATRA in a dose-dependent manner. This transcriptional activation was regulated through the receptors for retinoids because BMS-189453, an antagonist to the retinoid receptors, counteracted it in a dose-dependent manner. In conclusion, active metabolites of vitamin A, especially ATRA produced by RALDH2 play relevant roles during the repairing process of injured podocytes. The results obtained from PAN nephrosis rats might be applicable to human renal diseases.

Aldehyde Oxidoreductases↗
PubMed2002

Can bone marrow differentiate into renal cells?

A considerable plasticity of adult stem cells has been confirmed in a wide variety of tissues. In particular, the pluripotency of bone marrow-derived stem cells may influence the regeneration of injured tissues and may provide novel avenues in regenerative medicine. Bone marrow contains at least hematopoietic and mesenchymal stem cells, and both can differentiate into a wide range of differentiated cells. Side population (SP) cells, which are originally defined in bone marrow cells by high efflux of DNA-binding dye, seem to be a new class of multipotent stem cells. Irrespective of the approach used to obtain stem cells, the fates of marrow-derived cells following bone marrow transplantation can be traced by labeling donor cells with green fluorescence protein or by identifying donor Y chromosome in female recipients. So far, bone marrow-derived cells have been reported to differentiate into renal cells, including mesangial cells, endothelial cells, podocytes, and tubular cells in the kidney, although controversy exists. Further studies are required to address this issue. Cell therapy will be promising when we learn to control stem cells such as bone marrow-derived stem cells, embryonic stem cells, and resident stem cells in the kidney. Identification of factors that support stem cells or promote their differentiation should provide a relevant step towards cell therapy.

Animals↗
PubMed2002

In vivo gene transfer of hepatocyte growth factor to skeletal muscle prevents changes in rat kidneys after 5/6 nephrectomy.

Hepatocyte growth factor (HGF) has been reported to be a renal regeneration factor. We previously reported that HGF acts as a renotropic factor, inducing cell recovery from ischemic injury or drug toxicity. Gene transfer by electroporation, which uses plasmid DNA as the vector, has several advantages over the conventional gene transfer method using viral vectors, inducing the ability to perform repeated transfers without apparent immunologic responses to the DNA vector. We recently demonstrated that electroporation of the HGF gene into skeletal muscle was an effective treatment for liver injury in an animal model. We presently investigated prevention of development of chronic renal disease by repetitive HGF gene transfer in rats with 5/6 nephrectomy. Hepatocyte growth factor gene transfer-treated rats showed better growth in body weight than untreated rats. Histologic changes such as glomerulosclerosis and interstitial fibrosis were significantly ameliorated by HGF gene transfer compared with untreated rats. Hepatocyte growth factor gene transfer by electroporation into skeletal muscle is feasible and effective against morphologic injury in subtotally nephrectomized rats.

Animals↗