ABSTRACT
OBJECTIVES: Concentrations of plasminogen activator inhibitor-1 (PAI-1) are increased in obese individuals. One source of PAI-1 is adipocytes. Hypoxia develops within adipose tissue as it expands, presumably contributing to increased levels of sphingosine-1-phosphate (S1P). S1P is a breakdown product of sphingosine, ubiquitous in cell membranes. We have shown previously that S1P increases the expression of PAI-1 in human liver-derived cell line. In the present study, we aimed to determine whether hypoxia induces S1P in adipocytes, thereby potentially contributing to an increase in PAI-1 and hence constraints on fibrinolysis associated with obesity. MATERIALS AND METHODS: Mouse 3T3-L1 adipocytes were exposed to CoCl2 to simulate hypoxia. Assays were performed for PAI-1 mRNA (quantitative PCR) and S1P (high-performance liquid chromatography). RESULTS: The physiologic concentration of S1P increased PAI-1 mRNA expression. The S1P2 receptor antagonist attenuated the increase in PAI-1. Adipocytes expressed sphingosine kinase 1/2 (SPHK1/2) and S1P lyase, key enzymes involved in S1P production and degradation. Hypoxia increased SPHK activity and decreased S1P lyase mRNA. Hypoxia reduced cytosolic sphingosine and increased S1P release into conditioned medium. Inhibitors of ABCA1 and ABCC1 reduced the release of S1P into conditioned media. In obese patients with uncomplicated dyslipidemia and hypertension, plasma S1P was increased compared with that in nonobese and lean individuals. CONCLUSION: Hypoxia in adipose tissue of obesity can promote elaboration of S1P that binds to S1P2 receptors in an autocrine or a paracrine manner. S1P potentially contributes toward increased expression of PAI-1 and consequent constraints on fibrinolysis. S1P production and extracellular transport provide an attractive target for therapy to attenuate impaired fibrinolysis associated with obesity.
Subject(s)
Adipocytes/metabolism , Lysophospholipids/blood , Obesity/blood , Plasminogen Activator Inhibitor 1/blood , Sphingosine/analogs & derivatives , 3T3-L1 Cells , ATP Binding Cassette Transporter 1/metabolism , Aged , Aldehyde-Lyases/genetics , Aldehyde-Lyases/metabolism , Animals , Body Mass Index , Cell Hypoxia , Culture Media, Conditioned , Female , Humans , Male , Mice , Mice, Inbred C57BL , Middle Aged , Multidrug Resistance-Associated Proteins/metabolism , Obesity/diagnosis , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Plasminogen Activator Inhibitor 1/genetics , RNA, Messenger/metabolism , Receptors, Lysosphingolipid/metabolism , Signal Transduction , Sphingosine/blood , Sphingosine-1-Phosphate Receptors , Time Factors , Up-RegulationABSTRACT
We tested the effect of a fermented papaya preparation (FPP; ORI, Gifu, Japan) on redox balance gene expression in 11 healthy nonsmoker, teetotaller individuals subjected to a detailed dietary and lifestyle questionnaire who refrained from any multivitamin supplement or fortified food. Redox status was assessed by erythrocyte and plasma parameters together with related leukocyte mRNA (glutathione peroxidase [GPx], superoxide dismutase [SOD], catalase, 8-oxoguanine glycosylase [hOGG1]) before/after 6 grams of FPP supplementation. At 2 and 4 weeks after FPP administration, plasma parameters remained unchanged, whereas FPP significantly upregulated all tested gene expression (p < 0.05). Although posttranscriptional/translation protein modifications do occur and larger and longer studies are awaited, these preliminary data suggest that a transcriptomic modification of key redox and DNA repair genes may offer further insights when attempting to interrelate "nutragenomics" to clinical phenomena.
Subject(s)
Antioxidants/metabolism , Dietary Supplements , Gene Expression Regulation, Enzymologic/drug effects , Oxidants/metabolism , Plant Extracts/pharmacology , Adult , Carica/chemistry , Catalase/blood , Catalase/genetics , Catalase/metabolism , DNA Glycosylases/blood , DNA Glycosylases/genetics , DNA Glycosylases/metabolism , Female , Fermentation , Glutathione Peroxidase/blood , Glutathione Peroxidase/genetics , Glutathione Peroxidase/metabolism , Health , Humans , Male , Middle Aged , Oxidation-Reduction/drug effects , Pilot Projects , Superoxide Dismutase/blood , Superoxide Dismutase/genetics , Superoxide Dismutase/metabolism , Young AdultABSTRACT
The involvement of oxidative and nitrosative stress mechanisms in several biological and pathological processes including aging, cancer, cardiovascular and neurodegenerative diseases has continued to fuel suggestions that processes can potentially be modulated by treatment with free-radical scavengers and antioxidant. The fermented papaya preparation (FPP) derived from Carica papaya Linn was investigated for its ability to modulate oxidative DNA damage due to H2O2 in rat pheochromocytoma (PC12) cells and protection of brain oxidative damage in hypertensive rats. Cells pre-treated with FPP (50 microg/ml) prior to incubation with H2O2 had significantly increased viability and sustenance of morphology and shape. The human hepatoma (HepG2) cells exposed to H2O2 (50 microM) showed an olive tail moment of 10.56 +/- 1.44 compared to 1.37 +/- 0.29 of the solvent control. A significant reduction (P < or = 0.05) of DNA damage was observed at concentrations > or = 10 microg/ml FPP, with 50 microg/ml FPP reducing the genotoxic effect of H2O2 by about 1.5-fold compared to only H2O2 exposed cells.
