蝉花通过抑制肾小管NADPH氧化酶/氧化应激治疗糖尿病肾病的研究

目的:探讨蝉花对链脲佐菌素诱导的糖尿病大鼠肾小管损伤的改善作用,基于调控肾小管NADPH氧化酶/氧化应激延缓糖尿病肾损害。方法:动物实验分为对照组(CON)、蝉花组(CSM)、糖尿病组(DM)和蝉花治疗组(DM+CSM); 24周后检测24 h尿蛋白、血尿素氮、血肌酐;肾组织检测活性氧(ROS)、丙二醛(MDA)水平,分离肾小管组织并用Western-blot检测caspase-3蛋白表达,Masson染色观察肾组织纤维化情况。细胞实验以晚期糖基化终末产物(AGEs)刺激大鼠原代肾小管上皮细胞(TEC),蝉花干预后观察NADPH氧化酶及氧化应激变化。结果:DM组大鼠24 h尿蛋白、血肌酐、血尿素氮在24周均明显高于对照组;干预24周后,DM+蝉花组大鼠的24 h尿蛋白、血肌酐水平低于DM组,DM+蝉花组尿素氮水平和DM组相比有下降的趋势,但无统计学意义。DM组NGAL、KIM-1、Casepase-3、INT%表达水平明显高于对照组,DM+蝉花组中的各指标均明显低于DM组。DM组中MDA、ROS和8-OHd G水平均明显高于对照组,DM+蝉花组肾组织MDA、ROS和8-OHd G水平均明显低于DM组。在细胞实验中AGEs组的NADPH氧化酶活性和ROS水平明显高于对照组,AGEs+蝉花组的NADPH氧化酶活性和ROS水平低于AGEs组。结论:蝉花可通过抑制肾小管NADPH氧化酶/氧化应激治疗糖尿病肾病。

Effect of Sodium Chloride and Cadmium on the Growth, Oxidative Stress and Antioxidant Enzyme Activities of Zygosaccharomyces rouxii

Zygosaccharomyces rouxii is a salt-tolerant yeast species capable of removing cadmium(Cd) pollutant from aqueous solution. Presently, the physiological characteristics of Z. rouxii under the stress of sodium chloride(NaCl) and Cd are poorly understood. This study investigated the effects of NaCl and Cd on the growth, oxidative stress and antioxidant enzyme activities of Z. rouxii after stress treatment for 24 h. Results showed that NaCl or Cd alone negatively affected the growth of Z. rouxii, but the growth-inhibiting effect of Cd on Z. rouxii was reduced in the presence of NaCl. Flow cytometry assay showed that under Cd stress, NaCl significantly reduced the production of reactive oxygen species(ROS) and cell death of Z. rouxii compared with those in the absence of NaCl. The activities of superoxide dismutase(SOD), catalase(CAT), and peroxidase(POD) of Z. rouxii were significantly enhanced by 2%–6% NaCl, which likely contributed to the high salt tolerance of Z. rouxii. The POD activity was inhibited by 20 mg L-1Cd while the SOD and CAT activities were enhanced by 8 mg L-1 Cd and inhibited by 20 mg L-1 or 50 mg L-1 Cd. The inhibitory effect of high-level Cd on the antioxidant enzyme activities of Z. rouxii was counteracted by the combined use of NaCl, especially at 6%. This probably accounted for the decrease in Cd-induced ROS production and cell death of Z. rouxii after incubation with NaCl and Cd. Our work provided physiological clues as to the use of Z. rouxii as a biosorbent for Cd removal from seawater and liquid highly salty food.

Role of MGST1 in reactive intermediate-induced injury

Microsomal glutathione transferase (MGST1, EC 2.5.1.18) is a membrane bound glutathione transferase extensively studied for its ability to detoxify reactive intermediates, including metabolic electrophile intermediates and lipophilic hydroperoxides through its glutathione dependent transferase and peroxidase activities. It is expressed in high amounts in the liver, located both in the endoplasmic reticulum and the inner and outer mitochondrial membranes. This enzyme is activated by oxidative stress. Binding of GSH and modification of cysteine 49 (the oxidative stress sensor) has been shown to increase activation and induce conformational changes in the enzyme. These changes have either been shown to enhance the protective effect ascribed to this enzyme or have been shown to contribute to cell death through mitochondrial permeability transition pore formation. The purpose of this review is to elucidate how one enzyme found in two places in the cell subjected to the same conditions of oxidative stress could both help protect against and contribute to reactive oxygen species-induced liver injury.

Natural heme oxygenase-1 inducers in hepatobiliary function

Many physiological effects of natural antioxidants, their extracts or their major active components, have been reported in recent decades. Most of these compounds are characterized by a phenolic structure, similar to that of o-tocopherol, and present antioxidant properties that have been demonstrated both in vitro and in vivo. Polyphenors may increase the capacity of endogenous antioxidant defences and modulate the cellular redox state. Changes in the cellular redox state may have wide-ranging consequences for cellular growth and differentiation. The majority of in vitro and in vivo studies conducted so far have attributed the protective effect of bioactive polyphenols to their chemical reactivity toward free radicals and their capacity to prevent the oxidation of important intracellular components. However, in recent years a possible novel aspect inthe mode of action of these compounds has been suggested; that is, the ultimate stimulation of the heme oxygenase-1 （HO-1） pathway is likely to account for the established and powerful antioxidant/anti-inflammatory properties of these polyphenols. The products of the HO-catalyzed reaction, particularly carbon mon- oxide （CO） and biliverdin/bilirubin have been shown to exert protective effects in several organs against oxidative and other noxious stimuli. In this context, it is interesting to note that induction of HO-1 expression by means of natural compounds contributes to protection against liver damage in various experimental models. The focus of this review is on the significance of targeted induction of HO-1 as a potential therapeutic strategy to protect the liver against various stressors in several pathological conditions.

Iron increases HMOX1 and decreases hepatitis C viral expression in HCV-expressing cells

AIM： To investigate effects of iron on oxidative stress, heme oxygenase-1 （HMOX1） and hepatitis C viral （HCV） expression in human hepatoma ceils stably expressing HCV proteins. METHODS： Effects of iron on oxidative stress, HMOX1, and HCV expression were assessed in CON1 cells. Measurements included mRNA by quantitative reverse transcription-polymerase chain reaction, and protein levels by Western blots. RESULTS： Iron, in the form of ferric nitrilotriacetate,increased oxidative stress and upegulated HMOX1 gene expression. Iron did not affect mRNA or protein levels of Bach1, a repressor of HMOXl. Silencing the up-regulation of HMOXl nuclear factor-erythroid 2-related factor 2 （Nrf2） by Nrf2-siRNA decreased FeNTA-mediated up-regulation of HMOXl mRNA levels. These iron effects were completely blocked by deferoxamine （DFO）. Iron also significantly decreased levels of HCV core mRNA and protein by 80%-90%, nonstructural 5A mRNA by 90% and protein by about 50% in the Con1 full length HCV replicon cells, whereas DFO increased them. CONCLUSION： Excess iron up-regulates HMOXl and down-regulates HCV gene expression in hepatoma cells. This probably mitigates liver injury caused by combined iron overload and HCV infection.

Protective effect of dihydropteridine reductase against oxidative stress is abolished with A278C mutation

Objective: To evaluate the antioxidation of dihydrobiopterin reductase and to explore the effect of A278C mutation of the quinoid dihydropteridine reductase(QDPR) gene on its antioxidant activity. Methods: First, plasmids with different genes(wild and mutant QDPR) were constructed. After gene sequencing, they were transfected into human kidney cells(HEK293T). Then, the intracellular production of reactive oxygen species(ROS) and tetrahydrobiopterin(BH4) was detected after cells were harvested. Activations of nicotinamide adenine dinucleotide phosphate oxidase 4(NOX4), glutathione peroxidase 3(GPX3), and superoxide dismutase 1(SOD1) were analyzed to observe the oxidative stress after transfection. The expression of the neuronal nitric oxide synthase(n NOS) gene was analyzed by semiquantitative reverse-transcription polymerase chain reaction(RT-PCR). We also detected the activation of transforming growth factor β1(TGF-β1) by enzyme-linked immunosorbent assay(ELISA) to observe the connection of TGF-β1 and oxidative stress. Results: The exogenous wild-type QDPR significantly decreased the expression of n NOS, NOX4, and TGF-β1 and induced the expression of SOD1 and GPX3, but the mutated QDPR lost this function and resulted in excessive ROS production. Our data also suggested that the influence on the level of BH4 had no significant difference between mutated and the wild-type QDPR transfection. Conclusions: Wild-type QDPR played an important role in protecting against oxidative stress, but mutant QDPR failed to have these beneficial effects.