Erratum: Attenuation of postprandial blood glucose in humans consuming isomaltodextrin: carbohydrate loading studies.

[This corrects the article DOI: 10.1080/16546628.2017.1325306.].

Effects of isomaltodextrin in postprandial lipid kinetics: Rat study and human randomized crossover study.

Isomaltodextrin (IMD) is a novel dietary fiber-like polysaccharide: a type of α-glucan produced from starch using enzymes derived from microorganisms. The results of cohort studies show that dietary fiber can prevent cardiovascular disorders caused by lifestyle-related diseases such as metabolic syndrome. Inhibition of excess fat absorption by dietary fiber is known to be one of the mechanisms, and it is also known that the actions of dietary fiber vary depending on factors such as its structure or origin. Thus, we investigated the inhibitory actions of IMD on fat absorption, and analyzed its mechanism of action. In rats, the absorption of fat given by gavage was significantly lower at 1, 2, and 6 hours after IMD administration than after vehicle administration. In humans, IMD was associated with a lesser increase in blood triglycerides in subjects whose blood triglycerides were otherwise apt to rise. We also found by in vitro emulsion studies that IMD, which had no effect on digestive enzyme activity or emulsion formation, stabilized the micro size micelle by inducing enlarged micelle particle size and increased zeta potential. In conclusion, the mechanism of inhibition of fat absorption by IMD may be a delay in micelle particles accessing the intestinal epithelium through changes in the surface structure and the physical properties of the micelle particles.

Attenuation of postprandial blood glucose in humans consuming isomaltodextrin: carbohydrate loading studies.

Background: Isomaltodextrin (IMD) is a novel highly branched α-glucan and its function as a soluble dietary fiber is expected. Objective: The goal of this study was to evaluate the effects of IMD on postprandial glucose excursions in healthy people and to make the mechanism clear. Design: Twenty-nine subjects ingested a solution containing maltodextrin (MD) or sucrose with or without IMD. Fourteen subjects ingested a solution containing glucose with or without IMD. Blood glucose concentrations were then compared between the groups. Furthermore, in vitro digestion, inhibition of digestive enzymes, and glucose absorption tests were conducted. Results: IMD attenuated blood glucose elevation in the subjects with blood glucose excursions at the high end of normal following the ingestion of MD or sucrose or glucose alone. This effect of 5 g IMD was most clear. IMD was digested partially only by small intestinal mucosal enzymes, and maltase and isomaltase activities were weakly inhibited. Furthermore, IMD inhibited the transport of glucose from mucosal side to serosal side. Conclusions: IMD attenuated postprandial blood glucose, after the ingestion of MD or sucrose or glucose. As one of the mechanism, it was suggested that IMD inhibited the absorption of glucose on small intestinal mucosal membrane.

Glycemic, insulinemic and incretin responses after oral trehalose ingestion in healthy subjects.

BACKGROUND: Trehalose is hydrolyzed by a specific intestinal brush-border disaccharidase (trehalase) into two glucose molecules. In animal studies, trehalose has been shown to prevent adipocyte hypertrophy and mitigate insulin resistance in mice fed a high-fat diet. Recently, we found that trehalose improved glucose tolerance in human subjects. However, the underlying metabolic responses after trehalose ingestion in humans are not well understood. Therefore, we examined the glycemic, insulinemic and incretin responses after trehalose ingestion in healthy Japanese volunteers. METHODS: In a crossover study, 20 fasted healthy volunteers consumed 25 g trehalose or glucose in 100 mL water. Blood samples were taken frequently over the following 3 h, and blood glucose, insulin, active gastric inhibitory polypeptide (GIP) and active glucagon-like peptide-1 (GLP-1) levels were measured. RESULTS: Trehalose ingestion did not evoke rapid increases in blood glucose levels, and had a lower stimulatory potency of insulin and active GIP secretion compared with glucose ingestion. Conversely, active GLP-1 showed higher levels from 45 to 180 min after trehalose ingestion as compared with glucose ingestion. Specifically, active GIP secretion, which induces fat accumulation, was markedly lower after trehalose ingestion. CONCLUSIONS: Our findings indicate that trehalose may be a useful saccharide for good health because of properties that do not stimulate rapid increases in blood glucose and excessive secretion of insulin and GIP promoting fat accumulation.

Daily Intake of Trehalose Is Effective in the Prevention of Lifestyle-Related Diseases in Individuals with Risk Factors for Metabolic Syndrome.

We previously performed animal studies that suggested that trehalose potentially prevents the development of metabolic syndrome in humans. To evaluate this possibility, we examined whether trehalose suppressed the progression of insulin resistance in a placebo-controlled, double-blind trial in 34 subjects with a body mass index (BMI) ≥23. The subjects were divided into two groups and were assigned to ingest either 10 g/d of trehalose or sucrose with meals for 12 wk. During the study, body composition and blood biochemical parameters were measured at week 0, 8, and 12. These parameters were also measured 4 wk after the end of intake to confirm the washout of test substances. In the trehalose group, blood glucose concentrations after a 2-h oral glucose tolerance test significantly decreased following 12 wk of intake in comparison with baseline values (0 wk). When a stratified analysis was performed in the subjects whose percentage of truncal fat approached the high end of the normal range, the change in body weight, waist circumference, and systolic blood pressure were significantly lower in the trehalose group than in the sucrose group. Our data indicated that a daily intake of 10 g of trehalose improved glucose tolerance and progress to insulin resistance. Furthermore, these results suggested that trehalose can potentially reduce the development of metabolic syndrome and associated lifestyle-related diseases, such as type 2 diabetes.

Cholesteryl Pullulan Encapsulated TNF-α Nanoparticles Are an Effective Mucosal Vaccine Adjuvant against Influenza Virus.

We encapsulated tumor necrosis factor-α (TNF-α), a major proinflammatory cytokine, into cholesteryl pullulan (CHP) to prepare TNF/CHP nanoparticles. In this report, we describe the immune-enhancing capability of the nanoparticles to act as a vaccine adjuvant. TNF/CHP nanoparticles showed excellent storage stability and enhanced host immune responses to external immunogens. The nanoparticles were effective via the nasal route of administration for inducing systemic IgG1 as well as mucosal IgA. We applied the nanoparticles in a model experimental influenza virus infection to investigate their adjuvant ability. TNF/CHP nanoparticles combined with a conventional split vaccine protected mice via nasal administration against a lethal challenge of A/PR/8/34 (H1N1) influenza virus. Mechanistic studies showed that the nanoparticles enhanced antigen uptake by dendritic cells (DCs) and moderately induced the expression of inflammation-related genes in nasopharynx lymphoid tissue (NALT), leading to the activation of both B and T cells. Preliminary safety study revealed no severe toxicity to TNF/CHP nanoparticles. Slight-to-moderate influences in nasal mucosa were observed only in the repeated administration and they seemed to be reversible. Our data show that TNF/CHP nanoparticles effectively enhance both humoral and cellular immunity and could be a potential adjuvant for vaccines against infectious diseases, especially in the mucosa.

Anti-inflammatory effects of adenosine N1-oxide.

BACKGROUND: Adenosine is a potent endogenous anti-inflammatory and immunoregulatory molecule. Despite its promise, adenosine's extremely short half-life in blood limits its clinical application. Here, we examined adenosine N1-oxide (ANO), which is found in royal jelly. ANO is an oxidized product of adenosine at the N1 position of the adenine base moiety. We found that it is refractory to adenosine deaminase-mediated conversion to inosine. We further examined the anti-inflammatory activities of ANO in vitro and in vivo. METHODS: The effect of ANO on pro-inflammatory cytokine secretion was examined in mouse peritoneal macrophages and the human monocytic cell line THP-1, and compared with that of adenosine, synthetic adenosine receptor (AR)-selective agonists and dipotassium glycyrrhizate (GK2). The anti-inflammatory activity of ANO in vivo was examined in an LPS-induced endotoxin shock model in mice. RESULTS: ANO inhibited secretion of inflammatory mediators at much lower concentrations than adenosine and GK2 when used with peritoneal macrophages and THP-1 cells that were stimulated by LPS plus IFN-γ. The potent anti-inflammatory activity of ANO could not be solely accounted for by its refractoriness to adenosine deaminase. ANO was superior to the synthetic A1 AR-selective agonist, 2-chloro-N(6)-cyclopentyladenosine (CCPA), A2A AR-selective agonist, 2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamideadenosine hydrochloride (CGS21680), and A3 AR-selective agonist, N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA), in suppressing the secretion of a broad spectrum of pro-inflammatory cytokines by peritoneal macrophages. The capacities of ANO to inhibit pro-inflammatory cytokine production by THP-1 cells were comparable with those of CCPA and IB-MECA. Reflecting its potent anti-inflammatory effects in vitro, intravenous administration of ANO significantly reduced lethality of LPS-induced endotoxin shock. A significant increase in survival rate was also observed by oral administration of ANO. Mechanistic analysis suggested that the up-regulation of the anti-inflammatory transcription factor c-Fos was, at least in part, involved in the ANO-induced suppression of pro-inflammatory cytokine secretion. CONCLUSIONS: Our data suggest that ANO, a naturally occurring molecule that is structurally close to adenosine but is functionally more potent, presents potential strategies for the treatment of inflammatory disorders.

Variation in available cesium concentration with parameters during temperature induced extraction of cesium from soil.

Cesium extraction behavior of brown forest type soil collected from paddy fields in Fukushima nuclear accident affected areas was studied. In nitric acid or sulfuric acid solutions at elevated temperature, the concentration of Cs in soil available for extraction, m0, has been estimated on the basis of modified canonical equation and the equations derived from assumed equilibria. With the variation in temperature, mixing time, and soil to solvent ratio, the observed m0 values in 0.5 M acid solution ranged between 1.5 and 2.9 mg cesium per kilogram of soil. By increasing the acid concentration to 3 M, the value of m0 could be sharply increased to 5.1 mg/kg even at 95 °C. This variation in the extractable concentration of cesium with the parameters signifies the existence of different binding sites in the soil matrix. The results observed for uncontaminated sample could be reproduced with the radioactive cesium contaminated sample belonging to the same soil group.

Structural and mutational analysis of substrate recognition in kojibiose phosphorylase.

Glycoside hydrolase (GH) family 65 contains phosphorylases acting on maltose (Glc-α1,4-Glc), kojibiose (Glc-α1,2-Glc), trehalose (Glc-α1,α1,-Glc), and nigerose (Glc-α1,3-Glc). These phosphorylases can efficiently catalyze the reverse reactions with high specificities, and thus can be applied to the practical synthesis of α-glucosyl oligosaccharides. Here, we determined the crystal structures of kojibiose phosphorylase from Caldicellulosiruptor saccharolyticus in complex with glucose and phosphate and in complex with kojibiose and sulfate, providing the first structural insights into the substrate recognition of a glycoside hydrolase family 65 enzyme. The loop 3 region comprising the active site of kojibiose phosphorylase is significantly longer than the active sites of other enzymes, and three residues around this loop, Trp391, Glu392, and Thr417, recognize kojibiose. Various mutants mimicking the residue conservation patterns of other phosphorylases were constructed by mutation at these three residues. Activity measurements of the mutants against four substrates indicated that Trp391 and Glu392, especially the latter, are required for the kojibiose activity.

Dealing with the aftermath of Fukushima Daiichi nuclear accident: decontamination of radioactive cesium enriched ash.

Environmental radioactivity, mainly in the Tohoku and Kanto areas, due to the long living radioisotopes of cesium is an obstacle to speedy recovery from the impacts of the Fukushima Daiichi Nuclear Power Plant accident. Although incineration of the contaminated wastes is encouraged, safe disposal of the Cs enriched ash is the big challenge. To address this issue, safe incineration of contaminated wastes while restricting the release of volatile Cs to the atmosphere was studied. Detailed study on effective removal of Cs from ash samples generated from wood bark, household garbage, and municipal sewage sludge was performed. For wood ash and garbage ash, washing only with water at ambient conditions removed radioactivity due to (134)Cs and (137)Cs, retaining most of the components other than the alkali metals with the residue. However, removing Cs from sludge ash needed acid treatment at high temperature. This difference in Cs solubility is due to the presence of soil particle originated clay minerals in the sludge ash. Because only removing the contaminated vegetation is found to sharply decrease the environmental radioactivity, volume reduction of contaminated biomass by incineration makes great sense. In addition, need for a long-term leachate monitoring system in the landfill can be avoided by washing the ash with water. Once the Cs in solids is extracted to the solution, it can be loaded to Cs selective adsorbents such as Prussian blue and safely stored in a small volume.

Trehalose prevents adipocyte hypertrophy and mitigates insulin resistance in mice with established obesity.

Our group recently demonstrated that simultaneous administration of trehalose with a high-fat diet (HFD) suppresses adipocyte hypertrophy and mitigates insulin resistance in mice. For the present study, we hypothesized that similar effects of trehalose would be observed in mice with previously-established obesity. Obese mice were fed a HFD and drinking water containing 0.3 or 2.5% (weight/volume) trehalose or distilled water (DW) ad libitum for 8 wk. After 7 wk intake of a HFD and trehalose, fasting serum insulin levels and homeostasis model assessment-insulin resistance (HOMA-IR) in the 0.3% Tre/HFD group were significantly lower than those in the DW/HFD group (p<0.05). After 8 wk of treatment, mesenteric adipocytes in the 0.3% Tre/HFD group showed significantly less hypertrophy than those in the DW/HFD group. Mechanistic analysis indicated that levels of high molecular weight (HMW) adiponectin in the serum of the 0.3% Tre/HFD group were significantly higher than those in the DW/HFD group. The expression levels of insulin receptor substrate-1 (IRS-1) and insulin receptor substrate-2 (IRS-2) messenger RNA (mRNA) in muscle were also significantly increased by trehalose intake. Our data therefore suggest that administration of trehalose to obese mice mitigates insulin resistance by suppressing adipocyte hypertrophy and increasing serum HMW adiponectin, resulting in upregulation of IRS-1, and IRS-2 expression in muscle. These results further suggest that trehalose is a functional saccharide that may be used to prevent the progression of insulin resistance.

The cyanine Dye NK-4 improves scopolamine-induced memory impairments in mice.

The aim of this study is to evaluate the effects of NK-4, a kind of cyanine dye, on cholinergic memory deficits in mice. We examined whether NK-4 could reverse scopolamine-induced amnesia in mice since NK-4 displays a potent and selective inhibitory effect on acetylcholinesterase (AChE) in vitro. Intraperitoneal administration of NK-4 significantly reversed scopolamine-induced cognitive impairments in mice in the Y maze and the passive avoidance tests, and NK-4 also improved spatial learning ability in the Morris water maze test. Despite NK-4 displaying remarkable AChE inhibitory activity in vitro, we could not detect a significant reduction of AChE activity in brain homogenates of NK-4-treated mice. Although the mechanism through which NK-4 reverses cognitive impairments in scopolamine-treated mice remains unclear, these data suggest that NK-4 may have potential as a therapeutic agent for the treatment of dementia.

Purification and characterization of highly branched α-glucan-producing enzymes from Paenibacillus sp. PP710.

Highly branched α-glucan molecules exhibit low digestibility for α-amylase and glucoamylase, and abundant in α-(1→3)-, α-(1→6)-glucosidic linkages and α-(1→6)-linked branch points where another glucosyl chain is initiated through an α-(1→3)-linkage. From a culture supernatant of Paenibacillus sp. PP710, we purified α-glucosidase (AGL) and α-amylase (AMY), which were involved in the production of highly branched α-glucan from maltodextrin. AGL catalyzed the transglucosylation reaction of a glucosyl residue to a nonreducing-end glucosyl residue by α-1,6-, α-1,4-, and α-1,3-linkages. AMY catalyzed the hydrolysis of the α-1,4-linkage and the intermolecular or intramolecular transfer of maltooligosaccharide like cyclodextrin glucanotransferase (CGTase). It also catalyzed the transfer of an α-1,4-glucosyl chain to a C3- or C4-hydroxyl group in the α-1,4- or α-1,6-linked nonreducing-end residue or the α-1,6-linked residue located in the other chains. Hence AMY was regarded as a novel enzyme. We think that the mechanism of formation of highly branched α-glucan from maltodextrin is as follows: α-1,6- and α-1,3-linked residues are generated by the transglucosylation of AGL at the nonreducing ends of glucosyl chains. Then AMY catalyzes the transfer of α-1,4-chains to C3- or C4-hydroxyl groups in the α-1,4- or α-1,6-linked residues generated by AGL. Thus the concerted reactions of both AGL and AMY are necessary to produce the highly branched α-glucan from maltodextrin.

Effects of NK-4 in a transgenic mouse model of Alzheimer's disease.

Beta-amyloid (Aß) peptides are considered to play a major role in the pathogenesis of Alzheimer's disease (AD) and molecules that can prevent pathways of Aß toxicity may be potential therapeutic agents for treatment of AD. We have previously reported that NK-4, a cyanine photosensitizing dye, displays neurotrophic and antioxidant activities. In this study, we report the effects of NK-4 on the toxicity of Aß and on cognitive function and Aß concentration in a transgenic mouse model of AD (Tg2576). In vitro, NK-4 effectively protected neuronal cells from toxicity induced by Aß. In addition, it displayed profound inhibitory activities on Aß fibril formation. In vivo, Tg2576 mice received an intraperitoneal injection at 100 or 500 µg/kg of NK-4 once a day, five times a week for 9 months. Administration of NK-4 to the mice attenuated impairment of recognition memory, associative memory, and learning ability, as assessed by a novel object recognition test, a passive avoidance test, and a water maze test, respectively. NK-4 decreased the brain Aß concentration while increasing the plasma amyloid level in a dose-dependent manner. NK-4 also improved memory impairments of ICR mice induced by direct intracerebroventricular administration of Aß. These lines of evidence suggest that NK-4 may affect multiple pathways of amyloid pathogenesis and could be useful for treatment of AD.

Anti-oxidative and anti-aging activities of 2-O-α-glucopyranosyl-L-ascorbic acid on human dermal fibroblasts.

A stable ascorbic acid derivative, 2-O-α-glucopyranosyl-l-ascorbic acid (AA-2G), was evaluated and compared with ascorbic acid for its protective effect against cellular damage and senescence induced by hydrogen peroxide (H(2)O(2)). Pretreatment with AA-2G for 72 h promoted the proliferation of normal human dermal fibroblasts (NHDF) and protected against cell damage induced by H(2)O(2). In contrast, ascorbic acid increased the proliferation and protected against cell damage, only when culture medium containing ascorbic acid was replaced every 24 h during the pretreatment period. These results suggest that the effect of AA-2G is longer-lasting compared to that of ascorbic acid. Senescence associated-ß-galactosidase (SA-ß-gal) activity, a classical biomarker of cellular senescence, was increased in H(2)O(2)-exposed NHDF cells, but pretreatment or posttreatment with ascorbic acid or AA-2G significantly inhibited the increase in SA-ß-gal levels. AA-2G was more potent than ascorbic acid in down-regulating SA-ß-gal activity. Expression of SIRT1, which has attracted attention as an anti-aging factor in recent years, was significantly decreased in H(2)O(2)-exposed NHDF cells compared to untreated cells. However, pretreatment NHDF cells with AA-2G before H(2)O(2) exposure significantly inhibited this decrease in SIRT1 expression, whereas ascorbic acid had no effect. After H(2)O(2) exposure, the expression levels of p53 and p21 were increased in NHDF cells and pretreatment with AA-2G inhibited this increase. Together, these results suggest that AA-2G protects dermal fibroblasts from oxidative stress and cellular senescence. These characteristics indicate that AA-2G could become a promising material for its anti-aging properties.

[Activation of natural killer T cells by NK-4, a criptocyanine dye].

We previously reported that oral administration of NK-4, a criptocyanine dye, enhances interleukin (IL)-12-depend- ent interferon (IFN)-γ production by lipopolysaccharide (LPS)-stimulated mouse splenocytes. These findings raised a possibility that NK-4 potentiated IFN-γ production by T cells, natural killer (NK) cells or natural killer T (NKT) cells in response to IL-12 produced by macrophage and dendritic cells. To explore this possibility, we first analyzed percentages of T, NK or NKT cells in splenocytes of mice that were administered NK-4 orally for three days. The percentage of NKT cells in splenocytes from NK-4-treated mice was significantly (p<0.05) increased compared to vehicle-treated mice. When splenocytes were stimulated with α-galactosylceramide (α-GalCer), an NKT cell ligand, IFN-γ production by splenocytes from NK-4-treated mice tended to increase, while no difference in the IL-4 production and proliferation were observed between the vehicle- and NK-4-treated mice. When IFN-γ/IL-4 ratios were calculated in individual mice, the ratios were significantly (p<0.05) elevated in NK-4-treated mice. Furthermore, IL-12 production by α-GalCer-stimulated splenocytes from NK-4-treated mice was also significantly (p<0.05) increased. These results suggest that oral administration of NK-4 increases the population of type I NKT cells with potent IFN-γ-producing activities. Since IL-12 and IFN-γ have been shown to play important roles in anti-tumor immunity as well as in the defence against bacterial infection, our results further imply that NK-4 may provide a potential therapeutic tool in cancer immunotherapy.

Enzymatic properties of recombinant kojibiose phosphorylase from Caldicellulosiruptor saccharolyticus ATCC43494.

One kojibiose phoshorylase (KP) homolog gene was cloned from Caldicellulosiruptor saccharolyticus ATCC43494. Recombinant KP from C. saccharolyticus (Cs-KP) expressed in Escherichia coli showed highest activity at pH 6.0 at 85 °C, and was stable from pH 3.5 to 10.0 and up to 85 °C for phosphorolysis. Cs-KP showed higher productivity of kojioligosaccharides of DP ≧ 4 than KP from Thermoanaerobacter brockii ATCC35047.

Neurotrophic effects of a cyanine dye via the PI3K-Akt pathway: attenuation of motor discoordination and neurodegeneration in an ataxic animal model.

BACKGROUND: Neurotrophic factors may be future therapeutic agents for neurodegenerative disease. In the screening of biologically active molecules for neurotrophic potency, we found that a photosensitizing cyanine dye, NK-4, had remarkable neurotrophic activities and was a potent radical scavenger. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we evaluated the effect of NK-4 on the protection of neurons against oxidative damage and investigated the associated intracellular signaling pathways. Subsequently, we evaluated the effect of NK-4 in an animal model of neurodegeneration. In vitro, NK-4 showed dose-dependent protection of PC12 cells from toxicity induced by oxidative stress caused by hydrogen peroxide (H(2)O(2)) or 6-hydroxydopamine (6-OHDA). Comparison of extracellular signal-regulated kinase signaling pathways between treatment with NK-4 and nerve growth factor (NGF) using K252a, an inhibitor of the NGF receptor TrkA, revealed that NK-4 activity occurs independently of NGF receptors. LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, blocked the protective effect of NK-4, and NK-4 caused activation of Akt/protein kinase B, a downstream effector of PI3K. These results suggest that the neuroprotective effects of NK-4 are mediated by the PI3K-Akt signaling pathway. NK-4 treatment also attenuated stress-induced activation of SAPK/JNK, which suggests that NK-4 activates a survival signaling pathway and inhibits stress-activated apoptotic pathways independently of the TrkA receptor in neuronal cells. In vivo, administration of NK-4 improved motor coordination in genetic ataxic hamsters, as assessed by rota-rod testing. Histological analysis showed that cerebellar atrophy was significantly attenuated by NK-4 treatment. Notably, the Purkinje cell count in the treated group was threefold higher than that in the vehicle group. CONCLUSIONS/SIGNIFICANCE: These results suggest that NK-4 is a potential agent for therapy for neurodegenerative disorders based on the activation of survival signaling pathways.

Tryptanthrin inhibits Th2 development, and IgE-mediated degranulation and IL-4 production by rat basophilic leukemia RBL-2H3 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Tryptanthrin is a compound isolated from Polygonum tinctorium, which is a known folk medicine with various biological activities. AIM OF THE STUDY: Allergic diseases are initiated by the development of allergen-specific T helper type 2 (Th2) cells and amplified by the degranulation of and cytokine release from basophils and mast cells during an effector phase. We found that Tryptanthrin could down-regulate IL-4 production by Th2 cells, while IFN-γ production by Th1 cells was not affected. Since IL-4 produced by basophils and effector Th2 cells has been shown to play important roles in the development and amplification of Th2-dominated allergic responses, we examined the effects of Tryptanthrin on the initiation and effector phase responses of Type I allergy in vitro. MATERIALS AND METHODS: To determine the mechanisms of Tryptanthrin-induced down-regulation of IL-4 production, the expression of Th2-specific transcription factors, c-Maf and GATA-3, was analyzed by RT-PCR. The effects of Tryptanthrin on Th cell differentiation were evaluated using CD4(+) T cells purified from spleen cells of Sugi basic protein (SBP)-immunized BALB/c mice. In primary cultures, cells were stimulated with SBP and antigen-presenting cells under neutral or Th2-skewing conditions in the presence or absence of Tryptanthrin. Cytokines produced by differentiated Th cells in secondary cultures were analyzed by ELISA. The effects of Tryptanthrin on IgE-mediated degranulation and IL-4 production were determined using rat basophilic leukemia (RBL-2H3) cells. Phosphorylation of ERK1/2 and Akt in Tryptanthrin-treated RBL-2H3 cells was analyzed to determine the mechanism of Tryptanthrin actions. RESULTS: Tryptanthrin suppressed c-Maf mRNA expression in Th2 clone cells, and even under Th2-skewing conditions, Tryptanthrin inhibited differentiation toward the Th2 phenotype, which is an essential event for the initiation phase of allergic diseases. Tryptanthrin also inhibited the IgE-mediated degranulation of and IL-4 production by RBL-2H3 cells, probably due to inhibiting IgE-mediated signaling pathways, including the phosphorylation of ERK1/2 and Akt. CONCLUSION: These findings suggest that Tryptanthrin effectively inhibits the effector and exacerbation responses, as well as the initiator responses, of Type I allergy. Thus, Tryptanthrin may have beneficial effects for immediate-type allergic responses.

Trehalose prevents adipocyte hypertrophy and mitigates insulin resistance.

Trehalose has been shown to evoke lower insulin secretion than glucose in oral saccharide tolerance tests in humans. Given this hypoinsulinemic effect of trehalose, we hypothesized that trehalose suppresses adipocyte hypertrophy by reducing storage of triglyceride and mitigates insulin resistance in mice fed a high-fat diet (HFD). Mice were fed an HFD and given drinking water containing 2.5% saccharide (glucose [Glc], trehalose [Tre], maltose [Mal], high-fructose corn syrup, or fructose [Fru]) ad libitum. After 7 weeks of HFD and saccharide intake, fasting serum insulin levels in the Tre/HFD group were significantly lower than in the Mal/HFD and Glc/HFD groups (P < .05). Furthermore, the Tre/HFD group showed a significantly suppressed elevation of homeostasis model assessment-insulin resistance compared with the Mal/HFD group (P < .05) and showed a trend toward lower homeostasis model assessment-insulin resistance than the Glc/HFD group. After 8 weeks of feeding, mesenteric adipocyte size in the Tre/HFD group showed significantly less hypertrophy than the Glc/HFD, Mal/HFD, high-fructose corn syrup/HFD, or Fru/HFD group. Analysis of gene expression in mesenteric adipocytes showed that no statistically significant difference in the expression of monocyte chemoattractant protein-1 (MCP-1) messenger RNA (mRNA) was observed between the Tre/HFD group and the distilled water/standard diet group, whereas a significant increase in the MCP-1 mRNA expression was observed in the Glc/HFD, Mal/HFD, Fru/HFD, and distilled water/HFD groups. Thus, our data indicate that trehalose prevents adipocyte hypertrophy and mitigates insulin resistance in HFD-fed mice by reducing insulin secretion and down-regulating mRNA expression of MCP-1. These findings further suggest that trehalose is a functional saccharide that mitigates insulin resistance.