线粒体与胰岛β细胞研究进展

胰岛β细胞功能不能满足外周胰岛素的需求是所有类型的糖尿病的共同发病机制。在胰腺β细胞,线粒体将外源性营养物质代谢成能量输出,最终导致胰岛素释放。因此,线粒体功能障碍为β细胞衰竭和糖尿病发生的基础。线粒体调节通过多种途径——包括代谢偶联,线粒体质量的维护和活性氧的产生,以及与其他细胞器之间的相互作用调节β细胞功能。本文将评价线粒体生物起源和退化的主要影响因素和其在β细胞线粒体质量平衡中的作用,并着重阐述线粒体能量物质代谢相关酶调节和线粒体质量对胰岛β细胞功能的重要性,以及这些通路的缺陷如何最终引起糖尿病。明确β细胞线粒体功能障碍的原因可能有助于产生治疗糖尿病基础发病机制的新方法。     

新诊断早发DM2患者胰岛素抵抗及胰岛β细胞功能分析

近几年,2型糖尿病（DM2）年轻化趋势明显,儿童和青少年人数逐渐增多。目前糖尿病学界趋向于将诊断年龄≤40岁者定义为早发DM2,〉40岁为晚发DM2[1]。DM2的主要发病机制是胰岛素抵抗和β细胞功能减退。影响DM2患者胰岛素抵抗及胰岛β细胞功能的因素很多（包括高血糖、高血脂、肥胖等）。本文通过56例新诊断早发DM2患者及56例正常对照组的临床资料进行分析,探讨影响早发DM2患者胰岛素抵抗及胰岛β细胞功能减退的相关因素。     

阻断肾素血管紧张素系统对长期高脂喂养胰岛素抵抗大鼠胰岛UCP2和GCLC表达的影响

目的： 观察长期高脂喂养的胰岛素抵抗大鼠胰岛氧化应激机制以及阻断肾素血管紧张素系统（RAS）对其的影响,探讨RAS与氧化应激、糖代谢之间的关系。方法: 雄性Wistar大鼠分为正常饲养组（NC组）、高脂饲养组（HF组）、高脂+培哚普利组（FP组）、高脂+替米沙坦组（FM组）,后2组大鼠喂养16周后分别以培哚普利2 mg·kg-1·d-1（FP组,n=15）和替米沙坦10 mg·kg-1·d-1（FM组,n=15）干预,8周后行正常血糖高胰岛素钳夹试验评估外周胰岛素抵抗程度,行静脉葡萄糖耐量试验检测胰岛β细胞功能 ,以RT-PCR检测γ谷氨酰半胱氨酸连接酶的催化亚基（GCLC）的表达,以免疫组化法检测胰岛局部线粒体解偶联蛋白2（UCP2）水平,以比色法测定胰腺组织丙二醛（MDA）的含量。结果: 与正常饲养组相比,高脂饲养组的葡萄糖输注率（GIR）降低了31.8%,胰岛GCLC表达降低了31.5% ,局部UCP2相对浓度增加了17.0%,胰腺MDA含量增加了0.46倍（均P<0.01）,0-10 min胰岛素曲线下面积（AUC10-10）为(271.8±33.8)vs（282.7±29.8）mIU·L-1·min-1,糖刺激后早期胰岛素分泌降低,但无显著差异;培哚普利或替米沙坦干预后,GIR分别增加了27.8%和30.8%,胰岛GCLC表达分别增加了26.6%和26.6% ,局部UCP2相对浓度分别下降了13.0%和15.6%,胰腺MDA含量分别下降了18%和20%（均P<0.01）,FP、FM组之间无显著差异。结论: 阻断RAS可以改善高脂喂养大鼠的胰岛素抵抗和胰岛β细胞分泌功能,其机制可能为通过下调胰岛局部UCP2和上调GCLC的表达,减轻氧化应激损伤,从而保护胰岛β细胞功能。     

2型糖尿病的分子遗传学研究进展和预防策略

2型糖尿病是一种由遗传因素和环境因素相互作用所导致的复杂疾病。研究表明胰岛β细胞功能缺陷和胰岛素抵抗是导致2型糖尿病发生和发展的重要原因。与胰岛β细胞功能缺陷有关的基因主要有 CDKAL 1、CDKN 2 A／2 B、TCF 7 L 2等,而与胰岛素抵抗有关的基因主要有 PPAR-γ、HHEX、KCNQ 1等。众多大型临床试验研究结果显示,通过改变生活方式以及药物干预可以预防或延缓2型糖尿病的发生。本文综述了基因及其多态性与2型糖尿病胰岛β细胞功能缺陷和胰岛素抵抗的相关性及其作用机制的研究进展,并总结了在世界范围内预防2型糖尿病的基本策略。     

氧化应激诱导HepG2肝癌细胞凋亡的研究(英)

目的：直接暴露细胞于活性氧能诱导发生凋亡，本文研究氧化应激诱导HepG2肝癌细胞的死亡及其机制。方法：暴露细胞于2 mmol/L过氧化氢产生氧化应激，用DNA凝胶电泳检测细胞凋亡，用荧光染色法检测细胞线粒体膜电位变化，Western blotting检测细胞浆中细胞色素c变化，fluorometric assay kit检测caspase活性变化。结果：氧化应激作用于HepG2细胞后12 h开始发生凋亡；氧化应激作用后4 h，细胞线粒体膜电位明显下降；胞浆中细胞色素c浓度呈时间依赖性增高；氧化应激作用8 h、12 h后细胞内caspase-3、caspase-9活性分别升高6.7及3.6倍，但caspase-8活性无变化。结论：氧化应激能诱导HepG2肝癌细胞发生凋亡，其途径与线粒体通路及caspase激活有关。     

成纤维细胞生长因子19在肥胖和糖尿病中的作用

成纤维细胞生长因子19（FGF19）是一种内分泌激素,主要受胆汁酸的调节。FGF19有助于减轻体质量,多种减肥措施均通过提高FGF19水平来实现,且FGF19可逆转肥胖引起的线粒体功能障碍。糖尿病的主要致病机制为胰岛素抵抗和胰岛β细胞缺陷,由此可引起微血管病变和心血管疾病。FGF19可从根本上保护胰岛β细胞功能、改善胰...     

姜黄素活化肝细胞Nrf2抗氧化系统效应及缓解胰岛素抵抗作用机制研究

目的探讨姜黄素对HepG2细胞Nrf2信号功能的调控作用与其改善胰岛素抵抗的效应关系,并进一步研究高脂饮食诱导小鼠胰岛素抵抗时姜黄素干预对肝脏Nrf2系统功能及糖异生作用的影响。方法在人肝癌细胞HepG2上分别用葡萄糖氧化酶（GO）或长期胰岛素处理,分别制成氧化应激和高胰岛素血症胰岛素抵抗模型;用蛋白印迹方法（WB）检测姜黄素对Nrf2抗氧化系统的作用。另外,对细胞进行短时胰岛素刺激,观察胰岛素信号（PKBSer473磷酸化水平）变化。为研究姜黄素的整体动物药物作用,在高脂诱导的胰岛素抵抗小鼠模型用姜黄素进行干预（雄性C57BL/6J小鼠,给予高脂饲料加上3%的姜黄素）,在第25周进行丙酮酸耐量实验,并于第27周取肝脏组织检测Nrf2系统功能变化。结果姜黄素可明显激活HepG2细胞Nrf2系统,并对抗GO氧化应激所致的PKB磷酸化损害。在高脂饲喂小鼠胰岛素抵抗模型,姜黄素可改善丙酮酸耐量,提示其增强胰岛素作用（抑制肝脏糖异生）,从而缓解肝脏糖代谢异常;姜黄素还明显激活高脂肥胖小鼠肝脏受抑制的Nrf2信号功能。结论姜黄素通过增强内源性Nrf2系统功能对抗氧化应激,是其缓解肝细胞胰岛素抵抗的重要药理机理。     

衰老血管内皮细胞线粒体膜电位与活性氧的变化

背景：血管内皮细胞衰老、凋亡与再生的平衡对正常血管的功能维持具有极其重要的作用。而线粒体是机体细胞内的重要细胞器,除了合成ATP为细胞提供能量外,还控制细胞程序性死亡、以及衰老等多种病理生理的代谢过程。 目的：通过检测脐静脉内皮细胞传代过程中线粒体膜电位与活性氧的改变及其相互关系,从而探讨细胞衰老过程中所产生的功能障碍。 方法：体外培养人脐静脉内皮细胞,选取传代过程中的第2,4,6,8代细胞,采用流式细胞术检测细胞线粒体膜电位及活性氧变化。选取第2,8代细胞行透射电镜检查,观察正常及衰老细胞超微结构的改变。 结果与结论：传代衰老过程中,血管内皮细胞线粒体膜电位逐代降低,而胞内活性氧则出现由增加转而降低的过程。传代后期血管内皮细胞同早期内皮细胞相比,线粒体及内质网明显减少。说明内皮细胞在传代导致的复制性衰老过程中,线粒体膜电位降低,线粒体受损。而在早期传代过程中线粒体轻度受损,而活性氧产生增加,但在线粒体严重受损、功能严重退化过程中,活性氧产生降低。     

妊娠期糖代谢异常患者胰岛素抵抗和胰岛β细胞功能的研究

目的探讨妊娠期糖代谢异常患者的胰岛素抵抗和胰岛β细胞功能的变化,以及对妊娠结局的影响。方法选取在我院就诊的171例孕妇检查资料,按照75g葡萄糖耐量试验（0GTT）结果分为妊娠期糖尿病组（GDM）,妊娠期糖耐量受损组（GIGT）,妊娠期空腹血糖受损组（GIFG）和正常对照组（NGT）。对各组的OGTT、胰岛素释放试验结果进行统计分析,计算出胰岛素抵抗指数（HOMA-IR）,胰岛素分泌指数和胰岛素敏感指数,将结果进行比对分析。并对各组的妊娠结局进行分析。结果胰岛素抵抗指数（HOMA-IR）GDM组〉GIFG组〉GIGT组〉对照组（P〈0.05）。胰岛素分泌指数：GDM组     

糖尿病足部感染患者血液超敏C反应蛋白和纤维蛋白原浓度变化

糖尿病足是糖尿病最严重的慢性并发症之一，其发病机理甚为复杂，其中糖代谢异常、血液动力学异常及慢性炎症反应起着重要作用。血清超敏C反应蛋白（HS-CRP）是炎症时肝脏合成的一种急性时相蛋白，可能与糖尿病炎症因子介导的炎症反应导致胰岛B细胞功能受损及产生胰岛素抵抗有关。高浓度纤维蛋白原（Fib）引致血液粘度增高被认为与糖尿病足的发生密切相关。本研究通过观察36例糖尿病足患者血液HS-CRP和Fib的变化，探讨其对糖尿病足发生、发展所起的作用。     

Involvement of oxidative stress in the pathogenesis of diabetes

Pancreatic beta-cell failure is the common characteristic of type 1 and type 2 diabetes. Type 1 diabetes is induced by pancreatic beta-cell destruction, which is mediated by an autoimmune mechanism and consequent inflammatory process. Various inflammatory cytokines and oxidative stress produced by islet-infiltrating immune cells have been proposed to play an important role in mediating the destruction of beta cells. The JNK pathway is also activated by such cytokines and oxidative stress and is involved in beta-cell destruction. Type 2 diabetes is the most prevalent and serious metabolic disease affecting people all over the world. Pancreatic beta-cell dysfunction and insulin resistance are the hallmark of type 2 diabetes. Once hyperglycemia becomes apparent, beta-cell function gradually deteriorates, and insulin resistance is aggravated. This process is called "glucose toxicity." Under such conditions, oxidative stress is provoked, and the JNK pathway is activated, which is likely involved in pancreatic beta-cell dysfunction and insulin resistance. In addition, oxidative stress and activation of the JNK pathway are involved in the progression of atherosclerosis, which is often observed under diabetic conditions. Taken together, it is likely that oxidative stress and subsequent activation of the JNK pathway are involved in the pathogenesis of type 1 and type 2 diabetes.     

Insulin-like growth factor-1 protects against prion peptide-induced cell death in neuronal cells via inhibition of Bax translocation

Insulin-like growth factor-1 (IGF-1) is one of the most important components of bovine colostrum. It exhibits antiapoptotic and antioxidative activities. Prion diseases are neurodegenerative disorders caused by cell death through mitochondrial dysfunction and increasing generation of reactive oxygen species (ROS). This study examined the protective effect of IGF-1 on residues 106-126 of the cellular prion protein [PrP (106-126)]-mediated mitochondrial neurotoxicity and oxidative stress. In SH-SY5Y human neuronal cells, treatment with PrP (106-126) decreased the cell viability and IGF-1 pretreatment markedly blocked the PrP?(106-126)-induced neuronal cell death. IGF-1 inhibited PrP?(106-126)-induced intracellular ROS generation and mitochondrial oxidative stress. In addition, IGF-1 blocked the translocation of the Bax protein to the mitochondria induced by PrP (106-126). These results demonstrate that IGF-1 protects neuronal cells against PrP (106-126)-mediated neurotoxicity through an antioxidative effect and blockage of mitochondrial Bax translocation. The results also suggest that regulation of IGF-1 secretion may have a therapeutic potential in the management of mitochondrial dysfunction and oxidative stress-induced neurodegeneration.     

Fanconi anemia links reactive oxygen species to insulin resistance and obesity

Abstract Aims: Insulin resistance is a hallmark of obesity and type 2 diabetes. Reactive oxygen species (ROS) have been proposed to play a causal role in insulin resistance. However, evidence linking ROS to insulin resistance in disease settings has been scant. Since both oxidative stress and diabetes have been observed in patients with the Fanconi anemia (FA), we sought to investigate the link between ROS and insulin resistance in this unique disease model. Results: Mice deficient for the Fanconi anemia complementation group A (Fanca) or Fanconi anemia complementation group C (Fancc) gene seem to be diabetes-prone, as manifested by significant hyperglycemia and hyperinsulinemia, and rapid weight gain when fed with a high-fat diet. These phenotypic features of insulin resistance are characterized by two critical events in insulin signaling: a reduction in tyrosine phosphorylation of the insulin receptor (IR) and an increase in inhibitory serine phosphorylation of the IR substrate-1 in the liver, muscle, and fat tissues from the insulin-challenged FA mice. High levels of ROS, spontaneously accumulated or generated by tumor necrosis factor alpha in these insulin-sensitive tissues of FA mice, were shown to underlie the FA insulin resistance. Treatment of FA mice with the natural anti-oxidant Quercetin restores IR signaling and ameliorates the diabetes- and obesity-prone phenotypes. Finally, pairwise screen identifies protein-tyrosine phosphatase (PTP)-α and stress kinase double-stranded RNA-dependent protein kinase (PKR) that mediate the ROS effect on FA insulin resistance. Innovation: These findings establish a pathogenic and mechanistic link between ROS and insulin resistance in a unique human disease setting. Conclusion: ROS accumulation contributes to the insulin resistance in FA deficiency by targeting both PTP-α and PKR. Antioxid. Redox Signal. 00, 000-000.     

Reactive oxygen species in renal vascular function

Reactive oxygen species (ROS) are produced by the aerobic metabolism. The imbalance between production of ROS and antioxidant defence in any cell compartment is associated with cell damage and may play an important role in the pathogenesis of renal disease. NADPH oxidase (NOX) family is the major ROS source in the vasculature and modulates renal perfusion. Upregulation of Ang II and adenosine activates NOX via AT1R and A1R in renal microvessels, leading to superoxide production. Oxidative stress in the kidney prompts renal vascular remodelling and increases preglomerular resistance. These are key elements in hypertension, acute and chronic kidney injury, as well as diabetic nephropathy. Renal afferent arterioles (Af), the primary resistance vessel in the kidney, fine tune renal hemodynamics and impact on blood pressure. Vice versa, ROS increase hypertension and diabetes, resulting in upregulation of Af vasoconstriction, enhancement of myogenic responses and change of tubuloglomerular feedback (TGF), which further promotes hypertension and diabetic nephropathy. In the following, we highlight oxidative stress in the function and dysfunction of renal hemodynamics. The renal microcirculatory alterations brought about by ROS importantly contribute to the pathophysiology of kidney injury, hypertension and diabetes.     

Oxidative stress produced by marijuana smoke. An adverse effect enhanced by cannabinoids.

Marijuana (MJ) smoking produces inflammation, edema, and cell injury in the tracheobronchial mucosa of smokers and may be a risk factor for lung cancer. Because oxidative stress may mediate some of these effects, this study was designed to test the hypothesis that cannabinoids in MJ smoke contribute to cellular oxidative stress. Oxidative stress was evaluated in an endothelial cell line (ECV 304) following exposure to smoke produced from MJ cigarettes containing either 0, 1.77, or 3.95% Delta9-tetrahydrocannabinol (Delta9-THC). Brief exposure to smoke from 3.95% MJ cigarettes stimulated the formation of reactive oxygen species (ROS) by 80% over control levels and lowered intracellular glutathione levels by 81%. Smoke-induced ROS generation increased in a dose- and time-dependent manner. In contrast, exposure to smoke from MJ containing 0% Delta9-THC produced no increase in ROS despite a 70% decline in glutathione levels. Smoke from MJ containing 1.77% Delta9-THC stimulated intermediate levels of ROS. A brief, 30-min exposure to MJ smoke, regardless of the Delta9-THC content, also induced necrotic cell death that increased steadily up to 48 h of observation. MJ smoke passed through a Cambridge filter that removed particulate matter was 3.4-fold more active in ROS production compared with unfiltered smoke, suggesting that most of the oxidative effects are produced by the gaseous phase. Alveolar macrophages obtained from habitual MJ smokers displayed low levels of glutathione compared with macrophages from nonsmokers. We conclude that MJ smoke containing Delta9-THC is a potent source of cellular oxidative stress that could contribute significantly to cell injury and dysfunction in the lungs of smokers.     

Metabolomics reveals that carnitine palmitoyltransferase‐1 is a novel target for oxidative inactivation in human cells

Oxidative dysfunction in the metabolism has long been implicated in diverse biological disorders. Although a substantial number of metabolic enzymes are targeted for inactivation by oxidative stress, identifying those targets remains difficult due to a lack of comprehensive observations of the metabolism acting through the stress response. We herein developed a metabolomics strategy using integrative liquid chromatography‐mass spectrometry (LC‐MS) and observing rapid metabolomic changes in response to hydrogen peroxide (H₂O₂)‐induced oxidative stress in HeLa cells. Among the many metabolite changes detected, the most characteristic metabolites uniquely indicated carnitine palmitoyltransferase‐1 (CPT1), the critical enzyme for mitochondrial β‐oxidation of long‐chain fatty acids, to be a target for oxidative inactivation. We showed that the enzymatic activity of CPT1 significantly declined by H₂O₂ in several human cells. Interestingly, the inactivation was shown to be a direct effect of H₂O₂ in vitro, but substantially occurred when cells were cultured with some reagents that generate reactive oxygen species (ROS). Thus, our results suggest the generality of CPT1 inhibition under various stress conditions associated with ROS generation, providing an insight into a mechanism for oxidative dysfunction in mitochondrial metabolism. Our metabolome data additionally suggest that certain methyltransferase(s) may be targets of oxidative stress as well.     

Aluminum induces oxidative burst,cell wall NADH peroxidase activity,and DNA damage in root cells of Allium cepa L

Plants under stress incur an oxidative burst that involves a rapid and transient overproduction of reactive oxygen species (ROS: O₂^??, H₂O₂, ^?OH). We hypothesized that aluminum (Al), an established soil pollutant that causes plant stress, would induce an oxidative burst through the activation of cell wall‐NADH peroxidase (NADH‐PX) and/or plasma membrane‐associated NADPH oxidase (NADPH‐OX), leading to DNA damage in the root cells of Allium cepa L. Growing roots of A. cepa were treated with Al³⁺ (800 μM of AlCl₃) for 3 or 6 hr without or with the pretreatment of inhibitors specific to NADH‐PX and NADPH‐OX for 2 hr. At the end of the treatment, the extent of ROS generation, cell death, and DNA damage were determined. The cell wall‐bound protein (CWP) fractions extracted from the untreated control and the Al‐treated roots under the aforementioned experimental conditions were also subjected to in vitro studies, which measured the extent of activation of peroxidase/oxidase, generation of ^?OH, and DNA damage. Overall, the present study demonstrates that the cell wall‐bound NADH‐PX contributes to the Al‐induced oxidative burst through the generation of ROS that lead to cell death and DNA damage in the root cells of A. cepa. Furthermore, the in vitro studies revealed that the CWP fraction by itself caused DNA damage in the presence of NADH, supporting a role for NADH‐PX in the stress response. Altogether, this study underscores the crucial function of the cell wall‐bound NADH‐PX in the oxidative burst‐mediated cell death and DNA damage in plants under Al stress. Environ. Mol. Mutagen., 2012. © 2012 Wiley Periodicals, Inc.     

Endothelial function and oxidative stress.

Increased oxidative stress impairs endothelial function and is thought to mediate vascular disease. Several pathological conditions increase the production of reactive oxygen species (ROS) in the vascular wall, including hypercholesterolemia, diabetes, and hypertension. These conditions are associated with endothelial dysfunction and cardiovascular disease. Thus, overall vascular function is dependent upon the balance of oxidant and antioxidant mechanisms, which determines endothelial function. Endothelial function is usually defined as nitric oxide (NO) production and/or bioavailability. Because ROS can interact and inactivate NO, vascular oxidative stress can lead to decrease NO bioavailability. This results in endothelial dysfunction and increased risk of cardiovascular diseases. Several pharmacological approaches have been used to improve endothelial function and decrease oxidative stress. These include treatment modalities that augment the antioxidant defense mechanisms, increase NO production, and inhibit ROS-generating enzymes. This review provides an overview of the relationship between endothelial function and oxidative stress.     

Alterations in intracellular reactive oxygen species generation and redox potential modulate mast cell function

The administration of mercuric chloride (HgCl₂), gold compounds, or D -penicillamine to Brown Norway (BN) rats causes a T helper (Th)2 cell-associated autoimmune syndrome characterized by the production of a number of autoantibodies, marked elevation of serum IgE concentration, and tissue injury in the form of a vasculitis and arthritis. We have recently shown that the same compounds in vitro sensitize BN rat peritoneal mast cells for IgE-triggered mediator release and interleukin-4 mRNA production. We wished to test the hypothesis that these agents influence mast cell function via an effect on intracellular reactive oxygen species (ROS) production/redox balance. Mast cells were obtained from BN rats by peritoneal washout. Incubation with HgCl₂, gold compounds or D -penicillamine (the latter only in the presence of copper ions) led to the intracellular production of ROS as shown by the oxidative production of the fluorescent compound 2′,7′-dichlorofluorescein. Mast cells were more sensitive than splenocytes to this effect. Direct oxidative stress (exposure to H₂O₂) produced a similar sensitization for mediator release to that caused by HgCl₂. Inhibition of ROS formation by desferrioxamine or catalase diminished the enhancement of IgE-mediated serotonin release caused by HgCl₂, as did replenishment of intracellular glutathione. 2-Mercaptoethanol exacerbated the toxicity of HgCl₂, perhaps due to the formation of a lipophilic complex that enhanced HgCl₂ uptake. Blocking of glutathione synthesis increased the toxicity of HgCl₂, but also abolished any sensitizing effect on mediator release. These results support three main predictions of our hypothesis: (1) the compounds known to influence mast cell function all lead to the generation of ROS within the mast cell; (2) direct oxidative stress causes sensitization for mediator release by the mast cell; and (3) modulation of ROS production/redox balance within the mast cell modulates the effects of these compounds on mast cell function. The balance of oxidative/antioxidative influences may play an important role in the modulation of mast cell function, particularly in the context of chemically induced autoimmunity.