Osamu Handa

Silver nanoparticles as a safe preservative for use in cosmetics.

Concern is continuously raised regarding the safety of preservatives, which are crucial in most cosmetic preparations. The antimicrobial effects of silver (Ag) are well recognized; however, Ag has some limitations as a preservative, such as its interference with salts. In this study, we investigated the effects of recently synthesized Ag nanoparticles on microorganisms, the permeability of Ag nanoparticles in human skin, and the cytotoxicity of Ag nanoparticles in human keratinocytes under ultraviolet B irradiation. Ag nanoparticles were found to be very stable, and they did not exhibit sedimentation for over 1 year. Ag nanoparticles showed sufficient preservation efficacy against mixed bacteria and mixed fungi, and did not penetrate normal human skin. At concentrations of 0.002-0.02 parts per million, Ag nanoparticles had no effect on HaCaT keratinocytes and did not enhance ultraviolet B-induced cell death. These results suggest that Ag nanoparticles may have potential for use as a preservative in cosmetics. From the clinical editor: In this study, the effects of recently synthesized Ag nanoparticles were investigated on microorganisms, along with the skin permeability and the cytotoxicity in human keratinocytes under UVB-irradiation. Ag nanoparticles were found to be very stable, showed sufficient preservation efficacy against mixed bacteria and mixed fungi, and did not penetrate normal human skin. Ag nanoparticles appear to be suitable for use as a preservative in cosmetics.

Increased expression of microRNA in the inflamed colonic mucosa of patients with active ulcerative colitis

Background and Aims:  MicroRNA (miRNA) are endogenous, approximately 22‐nucleotide non‐coding RNA that suppress gene expression at post‐transcriptional levels by binding to the 3′‐untranslated region of specific mRNA targets through base‐pairing. It has been recently reported that miRNA have critical functions in key biological processes such as cell proliferation and cell death in various cancer cells. However, the relationship between intestinal inflammation and miRNA expression remains unclear. In the present study, we used microarray technology to identify miRNA induced in the colonic mucosa of patients with active ulcerative colitis (UC).

Enhanced intestinal inflammation induced by dextran sulfate sodium in tumor necrosis factor-alpha deficient mice.

Background and Aims: Tumor necrosis factor‐α (TNF‐α) is a potent pro‐inflammatory cytokine thought to be involved in the pathogenesis of inflammatory bowel disease. To further define the role of TNF‐α in intestinal inflammation, we studied the effects of dextran sulfate sodium (DSS) administration in mice with targeted deletions of TNF‐α gene.

Helicobacter pylori: a ROS-inducing bacterial species in the stomach

BackgroundReactive oxygen species (ROS) and reactive nitrogen species (RNS) have been reported to impact gastric inflammation and carcinogenesis. However, the precise mechanism by which Helicobacter pylori induces gastric carcinogenesis is presently unclear.AimThis review focuses on H. pylori-induced ROS/RNS production in the host stomach, and its relationship with gastric carcinogenesis.ResultsActivated neutrophils are the main source of ROS/RNS production in the H. pylori-infected stomach, but H. pylori itself also produces ROS. In addition, extensive recent studies have revealed that H. pylori-induced ROS production in gastric epithelial cells might affect gastric epithelial cell signal transduction, resulting in gastric carcinogenesis. Excessive ROS/RNS production in the stomach can damage DNA in gastric epithelial cells, implying its involvement in gastric carcinogenesis.ConclusionUnderstanding the molecular mechanism behind H. pylori-induced ROS, and its involvement in gastric carcinogenesis, is important for developing new strategies for gastric cancer chemoprevention.

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.

Suppression of intestinal ischemia-reperfusion injury by a specific peroxisome proliferator-activated receptor-γ ligand, pioglitazone, in rats

Abstract Neutrophil activation and tumor necrosis factor-α (TNF-α) induction play a critical role in ischemia-reperfusion-induced intestinal inflammation. Peroxisome proliferator-activated receptor-γ (PPAR-γ), a member of the nuclear hormone receptor superfamily, has recently been implicated as a regulator of inflammatory responses. The aim of the present study was to determine whether pioglitazone, a specific PPAR-γ ligand, can ameliorate reperfusion-induced intestinal injury in rats, and whether the agent can inhibit the increase in neutrophil accumulation associated with TNF-α expression. Intestinal damage was induced in male Sprague-Dawley rats by clamping the superior mesenteric artery for 30 min followed by reperfusion. Reperfusion after 30 min ischemia resulted in an increase in luminal protein concentrations with levels reaching a maximum after 60 min of reperfusion. In contrast, pretreatment with pioglitazone 2 h before ischemia inhibited the increase in luminal protein concentrations after 60 min reperfusion in a dose-dependent manner (1-30 mg/kg). The increase in tissue-associated myeloperoxidase activity, an index of neutrophil infiltration, after reperfusion was significantly inhibited by pretreatment with pioglitazone. Pioglitazone also inhibited increases in intestinal TNF-α protein and mRNA expression determined by ELISA and RT-PCR, respectively. In conclusion, activation of PPAR-γ may represent a novel approach to the treatment of intestinal inflammation induced by ischemia-reperfusion.

Molecular mechanisms involved in anti-inflammatory effects of proton pump inhibitors.

Abstract.ObjectiveInterleukin (IL)-8 has been reported to participate in neutrophil infiltration in Helicobacter pylori (H. pylori)-induced gastritis in humans. In this study, we investigated the anti-inflammatory actions beyond the suppression of acid secretion by proton pump inhibitors (PPI), such as omeprazole and lansoprazole, on IL-8 production by gastric epithelial cells (MKN45) and human umbilical vein endothelial cells (HUVEC) and on the transendothelial migration of polymorphonuclear neutrophils (PMN).Materials and methodsMKN45 and HUVEC were stimulated with H. pylori water extract (HPE) and IL-1β, respectively, and nuclear factor kappa B (NFκB) activation and subsequent IL-8 production was assessed in the absence or presence of PPI. We also assessed the effect of PPI on IL-8-induced PMN transendothelial migration and on the alteration of cytoplasmic calcium concentration in formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated PMN.ResultsHPE and IL-1β induced a significant increase in IL-8 production by MKN45 and HUVEC, respectively, along with NFκB activation, which was significantly inhibited by PPI. PPI also inhibited the IL-8-induced transendothelial migration of PMN and the fMLP-induced cytosolic calcium increase in PMN.ConclusionsPPI attenuate PMN-dependent gastric mucosal inflammation partly by interfering with NFκB activation in vascular endothelial cells and gastric epithelial cells, and partly by modulating the calcium concentration of PMN.

Pioglitazone, a PPAR-γ ligand, provides protection from dextran sulfate sodium-induced colitis in mice in association with inhibition of the NF-κB-cytokine cascade

Abstract Nuclear factor-κB-dependent up-regulation of inflammatory cytokines occurs in inflammatory bowel disease. We investigated the effect of pioglitazone, a peroxisome proliferator-activated receptor-γ ligand, on dextran sulfate sodium-induced colonic mucosal injury and inflammation in mice. Acute colitis was induced in female mice receiving 0, 1, 3, and 10 mg/kg i.p. of pioglitazone daily. Colonic mucosal inflammation was evaluated chemically and histologically. Thiobarbituric acid-reactive substances and tissue-associated myeloperoxidase activity were measured in intestinal mucosa as indices of lipid peroxidation and neutrophil infiltration, respectively. Colonic mRNA expression of pro-inflammatory cytokines and inducible nitric oxide synthase was measured by reverse transcription-PCR and nuclear factor-κB activation was evaluated by electrophoretic mobility shift assay. Dextran sulfate sodium administration resulted in decreases in body weight and colon length and increases in lipid peroxide and neutrophil accumulation of the intestine. In contrast, co-administration with pioglitazone prevented these changes. Transcripts coding for pro-inflammatory cytokines and inducible nitric oxide were expressed in high levels after the development of colitis, and pioglitazone markedly reduced mRNA expression of these genes. DNA binding activity of nuclear factor-κB was markedly increased, whereas in pioglitazone co-treated intestines the effect was significantly reduced. These data suggest that peroxisome proliferator-activated receptor-γ may be a novel therapeutic target for the therapy of inflammatory bowel disease.

Role of endothelial nitric oxide synthase-derived nitric oxide in activation and dysfunction of cerebrovascular endothelial cells during early onsets of sepsis

Sepsis-associated encephalopathy is an early manifestation of sepsis, resulting in a diffuse dysfunction of the brain. Recently, nitric oxide (NO) has been proposed to be one of the key molecules involved in the modulation of inflammatory responses in the brain. The aim of this study was to assess the role of NO in cerebrovascular endothelial cell activation/dysfunction during the early onsets of sepsis. To this end, we employed an in vitro model of sepsis in which cultured mouse cerebrovascular endothelial cells (MCVEC) were challenged with blood plasma (20% vol/vol) obtained from sham or septic (feces-induced peritonitis, FIP; 6 h) mice. Exposing MCVEC to FIP plasma for 1 h resulted in increased production of reactive oxygen species and NO as assessed by intracellular oxidation of oxidant-sensitive fluorochrome, dihydrorhodamine 123 (DHR 123), and nitrosation of NO-specific probe, DAF-FM, respectively. The latter events were accompanied by dissociation of tight junction protein, occludin, from MCVEC cytoskeletal framework and a subsequent increase in FITC-dextran (3-kDa mol mass) flux across MCVEC grown on the permeable cell culture supports, whereas Evans blue-BSA (65-kDa mol mass) or FITC-dextran (10-kDa mol mass) flux were not affected. FIP plasma-induced oxidant stress, occludin rearrangement, and MCVEC permeability were effectively attenuated by antioxidant, 1-pyrrolidinecarbodithioic acid (PDTC; 0.5 mM), or interfering with nitric oxide synthase (NOS) activity [0.1 mM nitro-L-arginine methyl ester (L-NAME) or endothelial NOS (eNOS)-deficient MCVEC]. However, treatment of MCVEC with PDTC failed to interfere with NO production, suggesting that septic plasma-induced oxidant stress in MCVEC is primarily a NO-dependent event. Taken together, these data indicate that during early sepsis, eNOS-derived NO exhibits proinflammatory characteristics and contributes to the activation and dysfunction of cerebrovascular endothelial cells.