Effects of Agmatine on Contrast-Induced Nephropathy in Rats and Rabbits.

Renal insufficiency secondary to contrast administration remains a prevalent and debilitating complication of angiographic procedures. Contrast-induced nephropathy (CIN) is a common clinical problem for which there is no effective medical treatment. However, agmatine has been shown to be effective against ischemia/reperfusion-induced acute kidney injury in rats, a similar condition to CIN. Our aim was to examine the protective effects of agmatine in a rat model of CIN and, based on those results, in a rabbit model of CIN. CIN in the rat model was induced by intravenous administration of indomethacin (10 mg/kg), Nω-nitro-L-arginine methyl ester (L-NAME) (10 mg/kg) and iopamidol (OYPALOMIN, 7.4 g iodine/kg) at 2 weeks after a unilateral nephrectomy. CIN in the rabbit model was induced by intrarenal arterial injection of only iopamidol (BYSTAGE, 4.8 g iodine/kg). Intravenous injection of agmatine (0.1 and 0.3 mmol/kg) did not attenuate the CIN-induced renal insufficiency in the rat model. Intravenous injection of agmatine (0.3 mmol/kg) attenuated the CIN-induced renal insufficiency in the rabbit model such as increases in blood urea nitrogen and plasma creatinine levels. Renal histological damage was also improved by the agmatine administration. The difference in effects of agmatine injection between CIN rats and CIN rabbits was caused by indomethacin and L-NAME administrations. These results indicate that agmatine prevents the development of CIN-induced renal insufficiency in rabbits, and the effect is accompanied by activation of nitric oxide synthase and subsequent increase of blood flow.

The Utility of Silk-elastin Hydrogel as a New Material for Wound Healing.

Cutaneous ulcers are treated with dressing materials and/or ointments to keep the wound in an appropriately moist environment. However, chronic cutaneous ulcers commonly have bacterial colonization that can cause local infection in such an environment. Therefore, the dressing materials and/or ointments should have antibacterial potency to treat chronic ulcers. Acute cutaneous wounds, by contrast, heal rapidly without local infection. The aim of treating acute cutaneous wounds is therefore not only wound closure but also preventing scar contracture after wound healing. However, no dressing materials or ointments available at present are simultaneously effective for preventing infection in chronic ulcers and reducing wound contracture in acute ulcers. Silk-elastin is a recombinant protein polymer with repeating units of silk-like and elastin-like blocks. Silk-elastin solution can self-assemble from a liquid to a hydrogel. We preliminarily reported that silk-elastin hydrogels have the potential to accelerate wound healing in decubitus ulcers of diabetic mice, which are animal models of severe, intractable cutaneous ulcers. In the present study, we examined the effects of silk-elastin hydrogels in chronic and acute ulcer models in comparison with conventional products (carboxymethyl cellulose gel). Silk-elastin hydrogels resulted in significantly higher epithelialization rates than conventional hydrogels in both the chronic and acute ulcer models and significantly larger areas of granulation tissue in acute ulcer models. These results show that silk-elastin hydrogel is a promising material for promoting the healing of cutaneous wounds, including decubitus ulcers, chronic ulcers, and acute ulcers.

Involvement of protein kinase C in reduction of aggregated protein and phosphorylation of CREB in glomeruli.

We previously demonstrated the cAMP-PKA pathway to be associated with the reduction in aggregated proteins such as immune complex in glomeruli. The aim of this study was to clarify whether PKC is involved in the reduction of aggregated protein and phosphorylation of CREB in aggregated protein-loaded glomeruli. Mice were injected with aggregated bovine serum albumin (a-BSA), and glomeruli were isolated. The a-BSA-injected mice produced more cyclic AMP and had more phosphorylated serine and phosphorylated CREB in their glomeruli than the controls. The expression of phospho-CREB increased with the accumulation of a-BSA. KT5720 and H7 suppressed the increase in phosphorylated CREB in a-BSA-loaded glomeruli and the decrease in accumulated a-BSA in the glomeruli. These findings suggest that PKC is associated with the reduction of aggregated protein and phosphorylation of CREB in aggregated protein-loaded glomeruli.

Advanced-glycation-end-product-cholesterol-aggregated-protein accelerates the proliferation of mesangial cells mediated by transforming-growth-factor-beta 1 receptors and the ERK-MAPK pathway.

Hyperglycemia and hyperlipidemia are considered critical to the development of diabetic nephropathy. The aim of this study is to clarify the effect of cholesterol on advanced-glycation-end-products and the mechanisms behind the advanced-glycation-end-product-cholesterol-aggregated bovine serum albumin (BSA)-induced proliferation of mesangial cells. Mesangial cells were treated with advanced-glycation-end-product-cholesterol-aggregated-BSA, and RNA and protein were isolated. Cholesterol caused a 1.5-fold increase in fluorescent intensity and 2-fold increase in advanced-glycation-end-products in vitro. Pyridoxamine, aminoguanidine, and N-acetyl-l-cycteine suppressed the production of advanced-glycation-end-product-cholesterol-aggregated-BSA. Advanced-glycation-end-product-cholesterol-BSA was analyzed by matrix-assisted-laser-desorption/ionization-time of flight mass spectrometry, and peaks were found to shift toward a higher mass. Advanced-glycation-end-product-cholesterol-aggregated-BSA induced overexpression of the mRNA of transforming growth factor-beta1, collagen type 1, collagen type 4 and receptor for advanced-glycation-end-products, and the proliferation of mesangial cells. The injection of advanced-glycation-end-product-cholesterol-aggregated-BSA caused glomerular changes and albuminuria in non-diabetic mice. A transforming-growth-factor-beta receptor 1 kinase inhibitor or Mitogen-activated-Protein-Kinase/Extracellular-Signal-regulated-Kinase kinase (ERK) inhibitor (U-0126) suppressed the proliferation of mesangial cells induced by advanced-glycation-end-product-cholesterol-aggregated-BSA dose-dependently. U-0126 inhibited the phosphorylation of ERK1/2 in advanced-glycation-end-product-cholesterol-aggregated-BSA treated mesangial cells. These findings suggested that cholesterol promotes the formation of advanced-glycation-end-products-protein and that advanced-glycation-end-product-cholesterol-aggregated protein stimulates mesangial cells to proliferate via transforming-growth-factor-beta receptors and the ERK-MAPK pathway in diabetic glomeruli.

Metformin reduces body weight gain and improves glucose intolerance in high-fat diet-fed C57BL/6J mice.

In an acute treatment experiment, metformin (150, 300 mg/kg, per os (p.o.)) markedly reduced the consumption of a high-fat diet (HFD) (45 kcal% fat-containing diet) for 2 h after the HFD was given to the fasted male C57BL/6J (B6) mice. In addition, metformin at a higher dose increased plasma active glucagon-like peptide-1 (GLP-1) levels at 1 h after the HFD was given. On the other hand, pioglitazone (12 mg/kg, p.o.) slightly increased the food intake but did not affect active GLP-1 levels when given at 6 and 12 mg/kg, p.o. In a long-team experiment for 9 weeks, metformin treatment (0.25, 0.5% in the HFD) resulted in reduction of body weight gain and HFD intake. When wet weights of various body fat pads of each mouse were measured at 9 weeks after treatment, metformin markedly decreased these weights. However, pioglitazone treatment (0.01, 0.02% in the HFD) did not have obvious effects on these parameters. Oral glucose tolerance test was carried out after 20-h fasting at 4 weeks post-treatment. Whereas metformin treatment (0.25, 0.5%) markedly improved glucose intolerance, pioglitazone treatment (0.02%) slightly improved this parameter. At 9 weeks, both metformin and pioglitazone markedly improved hyperglycemia and hyperinsulinemia. Metformin treatment also improved hyperleptinemia, whereas pioglitazone was ineffective. These results indicate that metformin reduces body weight gain and improves glucose intolerance in HFD-induced obese diabetic B6 mice.

Effects of kynurenine metabolites on mesangial cell proliferation and gene expression.

In the present study, we examined the effects of kynurenine metabolites on cultured mesangial cells (MCs) and demonstrated for the first time that they affect MC proliferation and gene expression. Anthranilic acid and 3-hydroxy-DL-kynurenine suppressed MC proliferation by 32% and 43%, respectively at 10(-6) M compared to the control. In contrast, quinolinic acid and l-kynurenine promoted MC proliferation by 49% and 35% at 10(-8) M respectively, although promoting activities declined at higher concentrations. In addition, quinolinic acid upregulated the gene expression of platelet-derived growth factor-B, collagen type-Ialpha1, and collagen type-IValpha1. However, the gene expression of hepatocyte growth factor (HGF) was downregulated. We further examined the gene expressions in the glomeruli of high serum IgA (HIGA) mice with IgA nephropathy using microarray technology and found that the gene expression of insulin-like growth factor-1 was higher, but that of HGF was lower at 40 weeks of age compared to 8 weeks of age. In Balb/c mice, the gene expression of three kynurenine pathway enzymes (kynurenine aminotransferase I, kynurenine aminotransferase II, and quinolinate phospho-ribosyltransferase) increased 2- to 3.5-fold, whereas those in HIGA mice did not change significantly. These results suggest that abnormalities in the kynurenine pathway are associated with the dysfunction of MCs and progression of chronic kidney diseases.

Involvement of hyperglycemia in deposition of aggregated protein in glomeruli of diabetic mice.

The aim of this study was to clarify the influence of hyperglycemia on the deposition of aggregated protein in the glomeruli of diabetic mice. KK-A(y) mice injected with aggregated bovine serum albumin accumulated more of it in the glomeruli than did ICR mice. There were no histological alterations in the glomeruli of KK-A(y) mice. KK-A(y) mice given voglibose in mouse-chow for 2 weeks had significantly reduced blood glucose, glycated albumin, and hemoglobin A(1C) levels compared with control mice. The voglibose-treated KK-A(y) mice were injected with aggregated bovine serum albumin and accumulated significantly less albumin in the glomeruli than did the control mice. Pioglitazone decreased blood glucose levels compared with the control, and reduced the glomerular deposition of aggregated albumin. Glomerular aggregated bovine serum albumin levels and blood glucose levels were reduced significantly by the injection of insulin. Six times more advanced glycation endproducts were produced from aggregated bovine albumin than from non-aggregated bovine albumin on incubation with glucose and L-lysine in vitro. Glucose-loaded ICR mice generated more advanced glycation endproducts from aggregated albumin, and had more aggregated bovine albumin in the glomeruli. It was suggested that hyperglycemia contributes to an increase in the deposition of aggregated protein in glomeruli even early on in diabetes.

Pioglitazone improves obesity type diabetic nephropathy: relation to the mitigation of renal oxidative reaction.

Medications to treat hyperglycemia and hyperinsulinemia are expected to inhibit the accumulation of advanced glycation end-products in the diabetic kidney and improve renal function by inhibiting oxidative reactions. In this study, we examined the effect of pioglitazone, an insulin sensitizer, on diabetic nephropathy. Feed containing pioglitazone at 0.01 or 0.02% was given to Zucker-fatty rats for 27 weeks. Pioglitazone reduced plasma glucose, plasma insulin, and blood HbAlc levels. It also decreased plasma total cholesterol, triglyceride, phospholipid and cystatin C levels and inhibited the increase in urine of 8-hydroxydeoxyguanosine and in plasma of malondialdehyde. In the histopathological examinations, pioglitazone inhibited diffusive or nodular thickening of the mesangial matrix, atrophy of the proximal convoluted tubule, thickening of the basement membrane of the tubule, and mild cellular infiltration (mostly small lymphocytes) in the stroma. Furthermore, pioglitazone inhibited the mRNA expression of the receptor for advanced glycation end-products (RAGE) and that of transforming growth factor-beta. Long-term administration of pioglitazone improved hyperglycemia lipid profiles, hypercholesterolemia, and hyperinsulinemia and had a protective effect on diabetic nephropathy in Zucker-fatty rats.

Downregulated expression in high IgA (HIGA) mice and the renal protective role of meprinbeta.

This study discusses the critical role of the metalloproteinase meprinbeta in the progression of glomerulonephritis. Using a microarray technique, the gene expression profiles in glomeruli isolated from high serum IgA (HIGA) mice with a purity of 97% or greater were examined. HIGA mice are a valid model of human IgA nephropathy (IgAN), with the typical pathological features of this condition, including a consistently high serum IgA level as well as dominant mesangial IgA deposition and mesangial enlargement. Among the many upregulated/downregulated genes after the development of IgAN, the downregulation of meprinbeta was intriguing. The expression level of the meprinbeta gene at 40 weeks of age was 52% of that observed at 8 weeks of age (prior to the development of IgAN), although in the control BALB/c mice, a 2.19-fold elevation was seen. These results were also confirmed by semi-quantitative RT-PCR and immunostaining analyses. As meprinbeta is a subunit of metalloproteinase meprins (meprin A, meprin B) and meprins are capable of proteolytically degrading extracellular matrix (ECM) components and proteolytically processing bioactive peptides, the downregulation of meprinbeta may contribute to the progression of glomerulonephritis and the eventual glomerular scarring. This working hypothesis was examined using an in vivo meprinbeta inhibition study. The inhibition of meprins by actinonin exacerbated some parameters of renal injury in mice afflicted with anti-glomerular basement membrane (anti-GBM) antibody-associated nephritis. These in vitro and in vivo results suggest that meprinbeta may play a protective role against the progression of renal injury through the degradation of ECM and bioactive peptides.

Protective effect of prostaglandin EP4-receptor agonist on anti-glomerular basement membrane antibody-associated nephritis.

Prostaglandin E(2)-receptor subtypes, EP(1), EP(2), EP(3), and EP(4), are present in the kidney. The aim of this study was to elucidate the anti-nephritic effect of an EP(4)-receptor agonist on an experimental nephritic model. Mice were injected i.v. with anti-glomerulus antiserum to induce nephritis. Nephritic glomeruli generated more prostaglandin E(2) (2.6 and 0.7 ng) and less cyclic AMP than normal glomeruli (11 and 26 pmol). The production of cyclic AMP in nephritic glomeruli increased 67% in response to AE1-329, an EP(4) agonist, at 10(-5) M. Nephritic glomeruli expressed a lesser amount of mRNA of prostaglandin E(2)-receptor subtypes as compared with normal glomeruli. AE1-329 was administered s.c. at 100 microg/kg per day for 3 weeks. AE1-329 suppressed the increase in creatinine and cholesterol compared to those in the control nephritic mice. AE1-329-treated nephritic mice had less crescentic glomeruli and less deposition of rabbit IgG (anti-glomerular basement membrane antibody) in glomeruli than the control mice. AE1-329 prevented the development of glomerulonephritis. These findings suggest that EP(4)-receptor agonists are a promising drug to prevent the development of glomerulonephritis.

Insufficient expression of cyclooxygenase-2 protein is associated with retarded degradation of aggregated protein in diabetic glomeruli.

To elucidate the involvement of cyclooxygenase (COX) in degradation of aggregated protein in diabetic glomeruli, we used streptozotocin (STZ)-induced diabetic mice and aggregated bovine serum albumin (a-BSA) as a model protein. There was a higher deposition of a-BSA in diabetic glomeruli compared to normal glomeruli 18 h after a-BSA injection at 4 and 8 weeks after STZ. Degradation of a-BSA was confirmed using isolated glomeruli. Diabetic glomeruli produced prostaglandin E(2) (PGE(2)) more than normal glomeruli in the basal level at 8 weeks. a-BSA caused further increase of PGE(2) production in normal glomeruli, but not in diabetic glomeruli. Niflimic acid, a selective COX-2 inhibitor, reduced PGE(2) production of normal glomeruli in the a-BSA loading group, but not that in the control group. In diabetic glomeruli, niflimic acid reduced PGE(2) production in both the control group and a-BSA loading group. In normal glomeruli, a-BSA increased expressions of both COX-2 mRNA and protein. However, in diabetic glomeruli, a-BSA increased COX-2 mRNA expression but not COX-2 protein expression. These results suggest that retarded degradation of aggregated protein in diabetic glomeruli is associated with lack of further expression of COX-2 protein and further production of PGE(2) in response to aggregated protein.

Increase in the deposition of aggregated protein in the glomeruli of spontaneously diabetic mice.

The aim of this study was to investigate the disposal of aggregated protein in the glomeruli of spontaneously diabetic mice. Diabetic mice, KK-A(y) and db/db, and age-matched ICR mice were injected intravenously with aggregated bovine serum albumin (a-BSA) at 0.6 mg/g, and the glomeruli and the blood were obtained. Diabetic mice had larger amounts of a-BSA in their glomeruli than the ICR mice, threefold in KK-A(y) and twofold in db/db, at 3 h after the a-BSA injection. Additionally, the disappearance of a-BSA was retarded in the diabetic glomeruli. KK-A(y) displayed a-BSA in the glomeruli 24 h after the a-BSA injection and db/db did after 12 h, while the ICR did by 8 h. In spite of increases of insulin to similar degrees in both strains of diabetic mice after the a-BSA injection, blood glucose levels markedly decreased in KK-A(y) compared with db/db. There were no histopathological alterations in the glomeruli of the diabetic mice. Depositions of a-BSA were confirmed to be higher in the diabetic glomeruli by the immunofluorescence technique, and KK-A(y) displayed higher depositions of a-BSA than did db/db. The present study suggests that hyperglycemia is involved in the increased deposition of aggregated protein in the glomeruli and that the degradation of aggregated protein is retarded in diabetic glomeruli.

[Anti-allergic action effect of Pseudolarix amabilis Rehd. extract and its efficacy on atopic dermatitis].

Pseudolarix amabilis Rehd. extract was examined in vitro for antibacterial effects, anti-inflammatory effects, and inhibitory effects on histamine release. Pseudolarix amabilis Rehd. extract was also examined for efficacy on dermatitis in atopic dermatitis model mice (NC mice) and effects on keratinous moisture level and transepidermal water loss in miniature pigs. Pseudolarix amabilis Rehd. extract had antibacterial effects on Staphylococcus aureus, Candida albicans, and Streptococcus pyogenes; however this antibacterial effect varied with the temperature at which and conditions under which Pseudolarix amabilis Rehd. was extracted. Pseudolarix amabilis Rehd. extract at the final concentration of 2 mg/mL significantly inhibited the hyaluronidase activity; and at 0.005, 0.05, and 0.5 mg/mL, it also significantly inhibited the histamine release. In the mice in which atopic dermatitis had been induced, 28-day administration of Pseudolarix amabilis Rehd. extract at 4 and 400 mg/mL significantly inhibited aggravation of dermatitis without having effects on body weight. In the dorsal skin of miniature pigs, Pseudolarix amabilis Rehd. extract at 4 and 400 mg/mL significantly increased keratinous moisture level with the increase in the number of dosing days, and caused no changes in transepidermal water loss. From the above results, it is clear that Pseudolarix amabilis Rehd. extract inhibits both proliferation of bacteria and inflammation caused by antigens. Furthermore, it is suggested that Pseudolarix amabilis Rehd. extract will serve as a medicinal drug which effectively moistens the skin and prevents and heals dermatitis.

[Analysis of scratching behavior in a picryl chloride induced atopic dermatitis model in mice].

To elucidate the actual state of scratching behavior of NC mice noted when PiCl-induced dermatitis occurs, the circadian rhythm in scratching behavior of this mouse model was examined, and the time when scratching behavior, which is useful to evaluate the severity of itch, occurs was assessed. A steroid drug (Prednisolone ointment), which has been confirmed to inhibit dermatitis from worsening, was used to examine whether or not, or how it inhibits scratching behavior in this mouse model. It became clear that scratching behavior increased during a period from the evening to the night in the animals which had not been sensitized (normal animals); compared with the day time, scratching behavior occurred more often in the nighttime. It also became clear that scratching behavior increased in the animals with PiCl-induced dermatitis increase in the frequency of induction of dermatitis, and Prednisolone ointment significantly inhibited scratching behavior in the animals in which dermatitis had been induced with PiCl six times. From these results, it can be said that scratching behavior increases in PiCl-induced mouse atopic dermatitis models correlatively with the increase in the frequency of induction of dermatitis, and steroid drugs decrease the frequency of the scratching behavior. In conclusion, it is strongly suggested that this mouse model is useful for development of therapeutic methods and novel medicinal drugs for atopic dermatitis.