Byeongwoo Ahn

Endocrine disruption and consequences of chronic exposure to ibuprofen in Japanese medaka (Oryzias latipes) and freshwater cladocerans Daphnia magna and Moina macrocopa

Despite frequent detection of ibuprofen in aquatic environments, the hazards associated with long-term exposure to ibuprofen have seldom been investigated. Ibuprofen is suspected of influencing sex steroid hormones through steroidogenic pathways in both vertebrates and invertebrates. In this study, the effect of ibuprofen on sex hormone balance and the associated mechanisms was investigated in vitro by use of H295R cells. We also conducted chronic toxicity tests using freshwater fish, Oryzias latipes, and two freshwater cladocerans, Daphnia magna and Moina macrocopa, for up to 144 and 21d of exposure, respectively. Ibuprofen exposure increased 17beta-estradiol (E2) production and aromatase activity in H295R cells. Testosterone (T) production decreased in a dose-dependent manner. For D. magna, the 48 h immobilization EC50 was 51.4 mg/L and the 21 d reproduction NOEC was <1.23 mg/L; for M. macrocopa, the 48 h immobilization EC50 was 72.6 mg/L and the 7d reproduction NOEC was 25mg/L. For O. latipes, 120 d survival NOEC was 0.0001 mg/L. In addition, ibuprofen affected several endpoints related to reproduction of the fish, including induction of vitellogenin in male fish, fewer broods per pair, and more eggs per brood. Parental exposure to as low as 0.0001 mg/L ibuprofen delayed hatching of eggs even when they were transferred to and cultured in clean water. Delayed hatching is environmentally relevant because this may increase the risk of being predated. For O. latipes, the acute-to-chronic ratio of ibuprofen was estimated to be greater than 1000. Overall, relatively high acute-to-chronic ratio and observation of reproduction damage in medaka fish at environmentally relevant ranges of ibuprofen warrant the need for further studies to elucidate potential ecological consequences of ibuprofen contamination in the aquatic environment.

Toxicity of perfluorooctane sulfonic acid and perfluorooctanoic acid on freshwater macroinvertebrates (Daphnia magna and Moina macrocopa) and fish (Oryzias latipes)

Because of their global distribution, persistence, and tendency to bioaccumulate, concerns about perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are growing. We determined the toxicity of PFOS and PFOA in several freshwater organisms, including two cladocerans, Daphnia magna and Moina macrocopa, and the teleost Oryzias latipes. In general, PFOS is approximately 10 times more toxic than PFOA in these organisms. In M. macrocopa, the median lethal concentration (LC50) was 17.95 mg/L for PFOS and 199.51 mg/L for PFOA. Moina macrocopa exhibited greater sensitivity than D. magna to both perfluorinated compounds in both acute and chronic exposures. In the 48-h acute toxicity test, M. macrocopa was approximately two times more sensitive than D. magna. In the 7-d chronic toxicity test, M. macrocopa showed significant reproductive changes at 0.31 mg/L for PFOS, which was approximately seven times lower than the effect concentrations observed over the 21-d exposure in D. magna. Two-generation fish toxicity tests showed that parental exposure to both compounds affected the performance of offspring. Unexposed progeny-generation (F1) fish exhibited elevated mortality and histopathological changes that were correlated with exposure in the parental generation (F0). Continuous exposure from F0 through F1 generations increased the extent of adverse effects. Considering the persistent nature of PFOS and PFOA, more research is required to determine potential consequences of long-term exposure to these compounds in aquatic ecosystems.

Resveratrol down-regulates interferon-γ-inducible inflammatory genes in macrophages: molecular mechanism via decreased STAT-1 activation.

Resveratrol (trans-3,4,5-trihydroxystilbene) is one of nonflavonoid polyphenolic phytoalexins found in various plant species, a number of which are components of human diet including grapes and red wines. Resveratrol has exerted several beneficial effects with anti-inflammation, cardioprotection and cancer chemoprevention. However, its mechanisms of action are not completely understood. In this study, we investigated effects of resveratrol on inflammatory gene expression in interferon (IFN)-γ alone-stimulated macrophages and proposed a molecular basis underlying the action. Resveratrol inhibited IFN-γ-induced production of nitric oxide (NO), IFN-γ-inducible protein-10 (IP-10), or the monokine induced by IFN-γ (MIG) in RAW 264.7 macrophages and also that of NO in primary macrophages derived from bone marrows of C3H/HeJ (toll-like receptor-4(-/-)) mice. Moreover, resveratrol diminished IFN-γ-induced protein levels of inducible NO synthase (iNOS), attenuated mRNA levels of iNOS, IP-10 or MIG as well as inhibited IFN-γ-induced promoter activity of iNOS gene, indicating that the phytoalexin could down-regulate inflammatory genes at the transcription level. To understand a mechanism of the action, we tested resveratrol could affect the signal transducers and activation of transcription-1 (STAT-1), a pivotal transcription factor in IFN-γ-induced expression of inflammatory genes. Resveratrol inhibited IFN-γ-induced transcriptional activity of STAT-1 in macrophages and also IFN-γ-induced Tyr(701) or Ser(727) phosphorylation of STAT-1. We then focused on protein kinases upstream STAT-1 phosphorylation. Resveratrol inhibited IFN-γ-induced activation of Janus kinase-2 (JAK-2) and also the extracellular signal-regulated kinase, in which JAK-2 was more sensitive. Taken together, this study proposes a new mechanism of resveratrol, blocking JAK/STAT-1 pathway that controls inflammatory responses in IFN-γ-activated macrophages.

Benzoxathiole Derivative Blocks Lipopolysaccharide-Induced Nuclear Factor-κB Activation and Nuclear Factor-κB-Regulated Gene Transcription through Inactivating Inhibitory κB Kinase β

Benzoxathiole derivatives have been used in the treatment of acne and have shown cytostatic, antipsoriatic, and antibacterial properties. However, little is known about the molecular basis for these pharmacological properties, although nuclear factor (NF)-κB activation is closely linked to inflammation and cell proliferation. Here, we demonstrate that the novel small-molecule benzoxathiole 6,6-dimethyl-2-(phenylimino)-6,7-dihydro-5H-benzo-[1,3]oxathiol-4-one (BOT-64) inhibits NF-κB activation with an IC50 value of 1 μM by blocking inhibitory κB(IκB) kinase β (IKKβ), and suppresses NF-κB-regulated expression of inflammatory genes in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. BOT-64 inhibits IKKβ-mediated IκBα phosphorylation in LPS-activated macrophages, resulting in sequential prevention of downstream events, including proteolytic degradation of IκBα, DNA binding ability, and transcriptional activity of NF-κB. BOT-64 inhibits LPS-inducible IKKβ activity in the cells and catalytic activity of highly purified IKKβ. Moreover, the effect of BOT-64 on cell-free IKKβ was abolished by substitution of Ser-177 and Ser-181 residues in the activation loop of IKKβ to glutamic acid residues, indicating a direct interaction site of benzoxathiole. BOT-64 attenuates NF-κB-regulated expression of inflammatory genes such as inducible nitric-oxide synthase, cyclooxygenase-2, tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in LPS-activated or expression vector IKKβ-transfected macrophages. Furthermore, BOT-64 dose-dependently increases the survival rates of endotoxin LPS-shocked mice.

Expression pattern of cytosolic glutathione peroxidase (cGPx) mRNA during mouse embryogenesis

The selenoprotein cytosolic glutathione peroxidase (cGPx) is ubiquitously distributed in a variety of organs, and its primary function is to protect oxidative damage. To investigate the spatial and temporal expression pattern of cGPx mRNA in embryogenesis, as this has not been studied before, reverse transcription-polymerase chain reaction (RT-PCR) was carried out in a thermal cycler using mouse-specific cGPx primers, and in situ hybridization was performed in whole embryos or embryonic tissues using digoxigenin-labeled mouse cGPx riboprobes. Expression of cGPx mRNA was detected in all the embryos retrieved from embryonic days (EDs) 7.5 to 18.5. On EDs 10.5–12.5, cGPx mRNA was highly expressed in the margin of forelimb and hindlimb buds and dorsally in the cranial neural tube, including the telencephalon, diencephalon, and hindbrain neural tube. On ED 13.5, cGPx mRNA was accumulated especially in vibrissae, forelimb and hindlimb plates, tail, and spinal cord. On EDs 14.5–16.5, cGPx mRNA was found in the developing brain, Rathke’s pouch, thymus, lung, and liver. On ED 17.5, the expression of cGPx mRNA was apparent in various tissues such as brain, submandibular gland, vibrissae, heart, lung, liver, stomach, intestine, pancreas, skin, and kidney. In particular, cGPx mRNA was greatly expressed in epithelial linings and metabolically active sites such as whisker follicles, alveolar epithelium of lung, surface epithelium and glandular region of stomach, skin epithelium, and cortex and tubules of kidney. Overall results indicate that cGPx mRNA is expressed in developing embryos, cell-specifically and tissue-specifically, suggesting that cGPx may function to protect the embryo against reactive oxygen species and/or hydroperoxides massively produced by the intracellular or extracellular environment.

Transient pulmonary fibrogenic effect induced by intratracheal instillation of ultrafine amorphous silica in A/J mice

In order to evaluate the degree of pulmonary fibrosis and to identify the fibrogenic mechanisms induced by ultrafine amorphous silica (UFAS), UFAS suspensions ( approximately 50microl) were instilled intratracheally into A/J mice at doses of 0, 2, 10 and 50mg/kg (n=5 per group). Mice were sacrificed at 24h, 1, 4 and 14 weeks after exposure. Gomoris trichrome staining revealed that UFAS induced severe alveolar epithelial thickening and pulmonary fibrosis at 1 week, though animals almost recovered at 4 and 14 weeks. The mRNA and protein levels of cytokines (IL-4, IL-10, IL-13 and IFN-gamma), matrix metalloproteinases (MMP-2, MMP-9 and MMP-10) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in lung tissues were significantly elevated at 24h and 1week post-treatment, though these levels decreased to near the control range at 4 and 14 weeks except IFN-gamma and MMP-2. These results demonstrate that UFAS can induce pulmonary fibrosis in the same way as crystalline silica. However, the degree of fibrosis observed was transient. This study shows that cytokines (IL-4, IL-10, IL-13 and IFN-gamma), MMPs (MMP-2, MMP-9 and MMP-10) and TIMP-1 play important roles in the fibrosis induced by the intratracheal instillation of UFAS.

The inhibitory effect of quercitrin gallate on iNOS expression induced by lipopolysaccharide in Balb/c mice

Quercetin 3-O-β-(2-galloyl)-rhamnopyranoside (QGR) is a naturally occurring quercitrin gallate, which is a polyphenolic compound that was originally isolated from Persicaria lapathifolia (Polygonaceae). QGR has been shown to have an inhibitory effect on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells. Therefore, this study was conducted to investigate the inhibitory effect of QGR on nitric oxide production and inducible nitric oxide synthases (iNOS) expression in LPS-stimulated Balb/c mice. To accomplish this, 10 mg/kg of QGR was administered via gavage once a day for 3 days. iNOS was then induced by intraperitoneal injection of LPS. Six hours after the LPS treatment the animals were sacrificed under ether anethesia. The serum levels of NO were then measured to determine if QGR exerted an inhibitory effect on NO production in vivo. LPS induced an approximately 6 fold increase in the expression of NO. However, oral administration of QGR reduced the LPS induced increase in NO by half. Furthermore, RT-PCR and western blot analysis revealed that the increased levels of iNOS expression that occurred in response to treatment with LPS were significantly attenuated in response to QGR pretreatment. Histologically, LPS induced the infiltration of polymorphonuclear neutrophils in portal veins and sinusoids and caused the formation of a large number of necrotic cells; however, pretreatment with QGR attenuated these LPS induced effects. Taken together, these results indicate that QGR inhibits iNOS expression in vivo as well as in vitro and has antiinflammatory potentials.

Green tea extract increases cyclophosphamide-induced teratogenesis by modulating the expression of cytochrome P-450 mRNA

The effects of green tea extract (GTE) on the fetal development and external, visceral and skeletal abnormalities induced by cyclophosphamide were investigated in rats. Pregnant rats were daily administered GTE (100mg/kg) by gavage for 7 d, from the 6th to 12th day of gestation, and intraperitoneally administered with cyclophosphamide (11mg/kg) 1h after the final treatment. On the 20th day of gestation, maternal and fetal abnormalities were determined by Cesarian section. Cyclophosphamide was found to reduce fetal and placental weights without increasing resorption or death. In addition, it induced malformations in live fetuses; 94.6%, 41.5% and 100% of the external (skull and limb defects), visceral (cleft palate and ureteric dilatation) and skeletal (acrania, vertebral/costal malformations and delayed ossification) abnormalities. When pre-treated with GTE, cyclophosphamide-induced body weight loss and abnormalities of fetuses were remarkably aggravated. Moreover, repeated treatment with GTE greatly increased mRNA expression and activity of hepatic cytochrome P-450 (CYP) 2B, which metabolizes cyclophosphamide into teratogenic acrolein and cytotoxic phosphoramide mustard, while reducing CYP3A expression (a detoxifying enzyme). The results suggest that repeated intake of GTE may aggravate cyclophosphamide-induced body weight loss and malformations of fetuses by modulating CYP2B and CYP3A.

The spatio-temporal expression pattern of cytoplasmic Cu/Zn superoxide dismutase (SOD1) mRNA during mouse embryogenesis

The cytoplasmic Cu/Zn-superoxide dismutase (SOD1) represents along with catalase and glutathione peroxidase at the first defense line against reactive oxygen species in all aerobic organisms, but little is known about its distribution in developing embryos. In this study, the expression patterns of SOD1 mRNA in mouse embryos were investigated using real-time RT-PCR and in situ hybridization analyses. Expression of SOD1 mRNA was detected in all embryos with embryonic days (EDs) 7.5–18.5. The signal showed the weakest level at ED 12.5, but the highest level at ED 15.5. SOD1 mRNA was expressed in chorion, allantois, amnion, and neural folds at ED 7.5 and in neural folds, notochord, neuromeres, gut, and primitive streak at ED 8.5. In central nervous system, SOD1 mRNA was expressed greatly in embryos of EDs 9.5–11.5, but weakly in embryos of ED 12.5. At EDs 9.5–12.5, the expression of SOD1 mRNA was high in sensory organs such as tongue, olfactory organ (nasal prominence) and eye (optic vesicle), while it was decreased in ear (otic vesicle) after ED 10.5. In developing limbs, SOD1 mRNA was greatly expressed in forelimbs at EDs 9.5–11.5 and in hindlimbs at EDs 10.5–11.5. The signal increased in liver, heart and genital tubercle after ED 11.5. In the sections of embryos after ED 13.5, SOD1 mRNA was expressed in various tissues and especially high in mucosa and metabolically active sites such as lung, kidney, stomach, and intestines and epithelial cells of skin, whisker follicles, and ear and nasal cavities. These results suggest that SOD1 may be related to organogenesis of embryos as an antioxidant enzyme.

Effect of Cordyceps militaris extract and active constituents on metabolic parameters of obesity induced by high-fat diet in C58BL/6J mice.

ETHNOPHARMACOLOGICAL RELEVANCEnCordyceps species which is well-known as winter worm summer grass has long been used as tonics and stimulants to enhance energy, exhibiting a potential for energy metabolism. Clinical trials have suggested their beneficial effect on lipid metabolic disorders such as hyperlipidemia.nnnMATERIALS AND METHODSnThe effect of Cordyceps militaris on metabolic parameters was investigated using C58BL/6J mice induced by high-fat diet (HFD). The effect was first determined by assessing the body and organ weight. For further investigation, sections of epididymal adipose tissue were stained with hematoxylin and eosin and the size of epididymal adipocyte was measured by Image analysis system. Fat accumulation in frozen liver sections was assessed by the Oil Red O staining and the plasma biochemical parameters were also assessed. Active constituents were characterized using chromatographic and spectroscopic analysis.nnnRESULTSnThe administration of Cordyceps militaris extract (CE) at the dose of 100mg/kg and 300 mg/kg reduced body weight gain and food efficiency ratio induced by HFD. The amount of epididymal fat and size of adipocytes were also decreased by CE treatment. In addition, liver weight and fat deposition in liver were dramatically reduced in CE-treated group. The treatment of CE also showed beneficial effects on plasma parameters related to lipid profiles. Further study for the characterization of active constituents of Cordyceps resulted in the isolation of two new compounds such as cordyrroles A (1) and B (7) together with 12 known compounds including pyrrole alkaloids and nucleotide derivatives. Among the isolated compounds, cordyrrole A significantly inhibited adipocyte differentiation and pancreatic lipase activity, whereas cordyrrole B was more effective at inhibiting pancreatic lipase. Cordycepin, a characteristic compound of Cordyceps militaris, decreased the rate of adipocyte differentiation.nnnCONCLUSIONnTreatment of CE inhibited HFD-induced metabolic disorders, mainly by improvement in metabolic parameters. As active constituents, pyrrole alkaloids and nucleotide derivatives were characterized. These results suggested that Cordyceps militaris might be beneficial for the treatment of metabolic disorders obesity through the combined actions of diverse constituents.