Satomi Akagiri

Astaxanthin Protects Mesangial Cells From Hyperglycemia-Induced Oxidative Signaling

Astaxanthin (ASX) is a carotenoid that has potent protective effects on diabetic nephropathy in mice model of type 2 diabetes. In this study, we investigated the protective mechanism of ASX on the progression of diabetic nephropathy using an in vitro model of hyperglycemia, focusing on mesangial cells. Normal human mesangial cells (NHMCs) were cultured in the medium containing normal (5 mM) or high (25 mM) concentrations of D‐glucose. Reactive oxygen species (ROS) production, the activation of nuclear transcription factors such as nuclear factor kappa B (NFκB) and activator protein‐1 (AP‐1), and the expression/production of transforming growth factor‐beta 1 (TGFβ1) and monocyte chemoattractant protein‐1 (MCP‐1) were evaluated in the presence or absence of ASX. High glucose (HG) exposure induced significant ROS production in mitochondria of NHMCs, which resulted in the activation of transcription factors, and subsequent expression/production of cytokines that plays an important role in the mesangial expansion, an important event in the pathogenesis of diabetic nephropathy. ASX significantly suppressed HG‐induced ROS production, the activation of transcription factors, and cytokine expression/production by NHMCs. In addition, ASX accumulated in the mitochondria of NHMCs and reduced the production of ROS‐modified proteins in mitochondria. ASX may prevent the progression of diabetic nephropathy mainly through ROS scavenging effect in mitochondria of mesangial cells and thus is expected to be very useful for the prevention of diabetic nephropathy. J. Cell. Biochem. 103: 1925–1937, 2007.

A Mouse Model of Metabolic Syndrome; Increase in Visceral Adipose Tissue Precedes the Development of Fatty Liver and Insulin Resistance in High-Fat Diet-Fed Male KK/Ta Mice.

To determine the relative contribution of obesity and visceral white adipose tissue (WAT) to metabolic syndrome, we developed a model that is susceptible to high-fat diet-induced obesity and insulin resistance using male KK/Ta mice. The ratio of WAT weight to body weight was greater in the high-fat diet group compared with the control group in 10-, 14-, and 22-week-old mice. The increase in visceral WAT preceded development of fatty liver and insulin resistance. Adiponectin mRNA expression in WAT was markedly decreased before the decrease in its plasma levels or the development of insulin resistance. Insulin resistance appeared in association with fatty infiltration and TNF-α expression in the liver in 22-week-old mice. These data indicate that our mouse model would be useful for future studies that investigate the role of visceral WAT and its products in the development of metabolic syndrome.

Lansoprazole, a Proton Pump Inhibitor, Mediates Anti-Inflammatory Effect in Gastric Mucosal Cells through the Induction of Heme Oxygenase-1 via Activation of NF-E2-Related Factor 2 and Oxidation of Kelch-Like ECH-Associating Protein 1

Induction of heme oxygenase-1 (HO-1) expression has been associated with cytoprotective and anti-inflammatory actions of lansoprazole, a proton pump inhibitor, but the underlying molecular mechanisms remain largely unresolved. In this study, we investigate the role of transcriptional NF-E2-related factor 2 (Nrf2), its phosphorylation/activation, and oxidation of Kelch-like ECH-associating protein 1 (Keap1) in lansoprazole-induced HO-1 up-regulation using cultured gastric epithelial cells (rat gastric mucosal cell line, RGM-1). HO-1 expression of RGM-1 cells was markedly enhanced in a time- and dose-dependent manner by the treatment with lansoprazole, and this up-regulation of HO-1 contributed to the inhibition of chemokine production from stimulated RGM-1 cells. Transfection of Nrf2-siRNA suppressed the lansoprazole-induced HO-1. An electrophoretic mobility shift assay showed increases in the nuclear translocation and stress-response elements (StRE) binding activity of Nrf2 proteins in RGM-1 cells treated with lansoprazole. Furthermore, in RGM-1 cells transfected with HO-1 enhancer luciferase reporter plasmid containing mutant StRE, lansoprazole-induced HO-1 reporter gene activity was diminished. Lansoprazole promoted the phosphorylation of extracellular signal-regulated kinase (ERK), and lansoprazole-induced HO-1 up-regulation was suppressed by U0126, an ERK-specific inhibitor. Phosphorylated Nrf2 protein was detected in the phosphoprotein fraction purified by a Pro-Q Diamond Phosphoprotein Enrichment kit. Finally, an oxidative form of the Keap1 protein was detected in lansoprazole-treated RGM-1 cells by analyzing S-oxidized proteins using biotinylated cysteine as a molecular probe. These results indicate that lansoprazole up-regulates HO-1 expression in rat gastric epithelial cells, and the up-regulated HO-1 contributes to the anti-inflammatory effects of the drug. Phosphorylation of ERK and Nrf2, activation and nuclear translocation of Nrf2, and oxidation of Keap1 are all involved in the lansoprazole-induced HO-1 up-regulation.

Bofutsushosan, an Oriental Herbal Medicine, Attenuates the Weight Gain of White Adipose Tissue and the Increased Size of Adipocytes Associated with the Increase in Their Expression of Uncoupling Protein 1 in High-Fat Diet-Fed Male KK/Ta mice

Bofutsushosan (BOF), an oriental herbal medicine, has been used as an anti-obesity drug in overweight patients. In the present study, to evaluate the anti-obesity and anti-diabetic effects of BOF, we investigated the effects of BOF on the white adipose tissue (WAT) weight, the size of adipocytes, adiponectin expression, and oral glucose tolerance test results in high-fat diet-fed male KK/Ta mice. In addition, the mRNA expression levels of uncoupling protein 1 (UCP1) and UCP2 mRNA in WAT and brown adipose tissue (BAT) were measured. 6-week-old KK/Ta mice were divided into four groups and fed a purified powdered basal diet (the BD group), a purified high-fat (HF) powdered diet containing suet powder at 37.5 g/100 g diet (the HF group), a high-fat diet plus 1.0% bofutsushosan (BOF) treatment (the HF + BOF group), or a high-fat diet plus 1.0% daisaikoto (DAI) treatment (the HF + DAI group) for 4 weeks. The weight of WAT and the size of adipocytes were increased in the HF group compared with those in the BD group, and these increases in the HF group were significantly inhibited in the HF + BOF group, but not affected in the HF + DAI group. There were no statistically significant differences in plasma levels and tissue mRNA levels of adiponectin among the four groups. There were no significant differences in UCP1 mRNA expression of BAT among the four groups. The expression of UCP1 mRNA in WAT was found in the HF + BOF group, but little expression was seen in the WAT of the BD, HF, or HF + DAI groups. The elevated plasma glucose levels and responses after the glucose loading in the HF group tended to decrease in the HF + BOF group. These results suggest that BOF decreases the weight and size gains of WAT along with up-regulating UCP1 mRNA in WAT in high-fat diet-fed mice.

Regular exercise prevents high-sucrose diet-induced fatty liver via improvement of hepatic lipid metabolism.

Fatty liver is known as the initial stage in nonalcoholic fatty liver disease. Epidemiological studies have shown that regular exercise prevents accumulation of hepatic lipids, although the underlying mechanism is unclear. The purpose of this study was to investigate the effect of exercise on fatty liver associated with hepatic lipid metabolism. KK/Ta mice (6 weeks old) were divided into sedentary and exercise groups and compared with sedentary Balb/c mice. All the mice were fed a high-sucrose diet for 12 weeks. The KK/Ta mice in the exercise group performed a treadmill running exercise at 20 m/min for 30 min (3 times per week). Twelve weeks of regular exercise suppressed the accumulation of lipid in the liver, along with reduction in the level of lipid in the plasma. The levels of carnitine palmitoyl transferase II, acyl-coenzyme A dehydrogenase, and trifunctional enzyme, which are rate-limiting enzymes in fatty acid oxidation in the liver, were elevated by exercise. In addition, the expression of fatty acid synthase, a key lipogenetic enzyme, was reduced by exercise. Furthermore, regular exercise decreased the expression of heat shock protein 47, a marker of hepatic fibrosis, in the liver. Our results suggest that regular exercise prevents fatty liver via improvement of hepatic lipid metabolism.

Identification of cysteinylated transthyretin, a predictive biomarker of treatment response to partially hydrolyzed guar gum in type 2 diabetes rats, by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry

Recent evidence has indicated that total fiber intake is inversely related to type 2 diabetes risk. The present study aimed to investigate the effects of chronic administration of partially hydrolyzed guar gum (PHGG), a water-soluble dietary fiber, on the occurrence of diabetes and its complications, fatty liver and nephropathy. We also identified predictive serum biomarkers of treatment response to PHGG by mass spectroscopy-based proteomic analysis using Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a good model of human non-insulin-dependent diabetes mellitus. In this study, at 5 weeks of age, OLETF rats and control strain Long-Evans Tokushima Otsuka (LETO) rats were fed a control diet or a high-fiber diet (5% PHGG) for 57 weeks. Body weight, food intake, oral glucose tolerance test, plasma insulin levels, and urine glucose and protein levels were regularly measured. Oral glucose tolerance tests (OGTT) and storage of serum in a deep freezer were conducted at the beginning of the experiment and every 4 weeks after overnight fasting during the experiments. PHGG treatment affected neither meal patterns nor the body weight of OLETF and LETO rats. Repeated measure analysis of variance revealed significant differences in fasting plasma glucose and plasma glucose at 2 h after OGTT between control OLETF (OLETF-C) rats and OLETF rats treated with PHGG (OLETF-F). The glucose response determined by the area under the curve of OGTT was significantly greater in OLETF-C rats than that in OLETF-F rats at 25 weeks of age. HOMA-IR, an index of insulin resistance, increased at 25 weeks of age in OLETF-C rats, while this increase was significantly inhibited in OLETF-F rats. At 62 weeks of age, PHGG treatment significantly improved hepatic steatosis as well as renal mesangial matrix accumulation in OLETF rats. To identify the risk marker for diabetes mellitus by SELDI-TOF MS, we collected sera from 21-week-old individuals. Among the 12 specific peaks that were risk marker candidates for diabetes mellitus, the m/z 13,720 peak was identified as that of cysteinylated transthyretin by sequencing of four tryptic peptides using tandem mass spectrometry and peak distribution around the m/z 13,720 peak in the SELDI-TOF spectra. In conclusion, we found that chronic treatment with PHGG improved insulin resistance, delayed the onset of diabetes, and inhibited the development of diabetic complications, as well as identified cysteinylated transthyretin as a predictive biomarker of treatment response to PHGG in OLETF rats.

Static electric field by high voltage alternating current ameliorates collagen-induced arthritis in mice via the inhibition of IL-1β expression.

Background and aim: The therapy of placing a living body in a static electric field by high voltage alternating current (EF-HVAC) has been developed in the field of complementary and integrative medicine in Japan. The aim of this study was to investigate whether the exposure of EF-HVAC ameliorated collagen-induced arthritis (CIA) in mice.Methods: CIA was induced in female DBA/1 mice by the injection of anti-type II collagen antibody and lipopolysaccharide. The group of EF-HVAC treatment was exposed EF-HVAC with a high voltage value of 12.7 KV for 6 hours per day in the closed cage starting on the day of the injection with anti-type II collagen antibody and throughout the remaining study period.Results: Both clinical arthritis scores as well as histological findings of joint inflammation were significantly reduced in mice treated with EF-HVAC compared to untreated mice. Further, the treatment with EF-HVAC significantly inhibited the increased expression of interleukin -1? mRNA in paws at day 3 after induction of arthritis. In conclusion, the exposure to EF-HVAC protected from the synovial inflammation of CIA in mice.Conclusion: Based on these data, the beneficial effects of EF-HVAC on a murine rheumatoid arthritis model may be attributed to its anti-inflammatory properties.