Nitric oxide donors suppress erythropoietin production in vitro

 Many inflammatory diseases are associated with a hypoproliferative anaemia. Patients with this anaemia often present with serum erythropoietin (EPO) concentrations that are too low for the degree of their anaemia. Proinflammatory cytokines, in addition to their inhibitory effects on proliferation of erythroid progenitors, could contribute to the pathogenesis of this anaemia by reducing EPO production. Because several cytokines stimulate nitric oxide (NO) synthase we propose that nitric oxide might mediate the suppression of EPO production during inflammation. In order to test this hypothesis we investigated the effects of NO donors on 24-h hypoxia-induced EPO production in the hepatocellular carcinoma cell line HepG2. Following application of the NO donors sodium nitroprusside (SNP), 3-morpholinosydnonimine (SIN-1), and S-nitroso-N-acetyl-D, L-penicillamine (SNAP), EPO production was dose-dependently reduced: compared to the untreated control EPO production was lowered by 89% with SNP (1000 μM), by 66% with SIN-1 (1000 μM), and by 72% with SNAP (500 μM). In contrast, 8-bromo-cGMP did not inhibit EPO formation. Since pyrogallol (300 μM) and H₂O₂ (250 μM) showed a comparable suppression of EPO synthesis, we propose that NO might affect EPO production either by a similar direct influence on the cellular redox state or via increasing the cellular content of reactive oxygen species. Received: 12 July 1996 / Received after revision and accepted: 17 July 1996     

Hydroxyl radicals and nitric oxide in neurotoxicity and neuroprotection

In the light of both neurodestructive and neuroprotective properties of nitric oxide, we have analysed the influence of hydroxyl radicals in these actions of nitric oxide. Requirement of superoxide anions to generate the neurotoxic peroxynitrite and the fact that it decomposes to form the more cytotoxic hydroxyl radicals at physiological pH, indicate the active involvement of the latter molecule in the neurotoxic action. Recent evidences also indicates that nitric oxide can act as an antioxidant in vitro and in vivo. Hence, it is suggested that it is time for a critical in vivo analysis of this molecule during a number of neurotoxic events to conclusively establish its role in neuroprotection and/or neurotoxicity.     

The roles of endogenous reactive oxygen species and nitric oxide in triptolide-induced apoptotic cell death in macrophages

Triptolide, a major active component extracted from the root of Tripterygium wilfordii Hook f, has been shown to possess potent immunosuppressive and anti-inflammatory properties. In the present report, we reported that triptolide increased the generation of reactive oxygen species (ROS) and nitric oxide (NO) and induced apoptosis of RAW 264.7 cells in a dose-dependent manner (5-25 ng/ml). The antioxidant, reduced glutathione (GSH), significantly inhibited triptolide-induced apoptosis and inhibited the degradation of Bcl-2 protein, disruption of mitochondrial membrane potential, release of cytochrome c from mitochondria into the cytosol, activation of caspase-3, and cleavage of poly-(ADP-ribose)-polymerase. The inducible nitric oxide synthase-specific inhibitor 1400w blocked triptolide-induced apoptosis, but did not alter mitochondria disruption and caspase-3 activation. These results, for the first time, implicated that the increased endogenous ROS and NO co-mediated triptolide-induced apoptosis in macrophages. ROS initiated triptolide-induced apoptosis by the mitochondria signal pathway, while the apoptotic cell death mediated by NO was not via mitochondria collapse and caspase-3 activation. In addition, combining mathematical calculation and computer simulation based on our conventional experimental results, we set and validated the apoptotic model and provided more dynamic processes of triptolide-induced apoptotic cascade in macrophages.     

Endothelial aging and gender

The endothelium plays a pivotal role in maintaining vascular homeostasis, mainly by the production of the relaxing factor nitric oxide, which protects the vessel wall from the development of atherosclerosis. Aging is a powerful cardiovascular risk factor, associated with endothelial dysfunction both in normotensive subjects and in hypertensive patients. Premenopausal normotensive women are protected against the deleterious effect of aging on endothelial function, and age-related impairment of endothelial function is attenuated in premenopausal hypertensive women. This protective effect on endothelium seems to be mediated by endogenous estrogen, which preserves nitric oxide availability by activating the l-arginine-NO pathway in normotensive women and by inhibiting reactive oxygen species generation. Whether endogenous androgen may modulate endothelial function and the mechanisms involved are still unsolved issues, since data concerning the effect of testosterone on endothelium are scanty and contradictory.     

Endothelial dysfunction and vascular disease in later life

The endothelium plays a primary role in the modulation of vascular tone and structure, through production of the relaxing factor nitric oxide, which acts by protecting the vessel wall from the development of atherosclerosis and thrombosis. A dysfunctioning endothelium, characterized by reduced nitric oxide availability, can be a promoter of atherosclerosis. Ageing is a well-documented cardiovascular risk factor. One of the possible physiopathological mechanisms whereby increasing age may lead to cardiovascular damage is the promotion of endothelial dysfunction. In humans, age-related impairment in endothelium-dependent vasodilation has been well documented in different vascular districts and involves the impairment of nitric oxide activity secondary to oxidative stress generation. Regular physical training is an important non-pharmacological intervention which protects the vascular endothelium from ageing-related alterations and ameliorates the cardiovascular risk profile among the elderly population.     

MicroRNA-155 induction by Mycobacterium bovis BCG enhances ROS production through targeting SHIP1

Macrophages play a critical role in the host immune response against mycobacterial infection. Our previous study has demonstrated that microRNA-155 (miR-155), one of the most important small non-coding RNAs in the immune system, promotes oxygen-independent mycobacterial killing in macrophages. However, little is known regarding the role of miR-155 in modulating oxygen-dependent mycobactericidal response in macrophages, including the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). In the present study, we demonstrated that miR-155 was increased in macrophages after Mycobacterium bovis bacille Calmette-Guérin (BCG) infection. Moreover, the BCG-induced upregulation of miR-155 in macrophages was dependent on TLR2, NF-κB and JNK signaling pathways. More importantly, our study explored that miR-155 significantly elevated ROS production in macrophages, although miR-155 had no influence on the inducible nitric oxide synthase (iNOS) expression or nitric oxide (NO) production. In addition, our study demonstrated that miR-155 repressed the expression of src homology 2 (SH2) containing inositol 5-phosphatase1 (SHIP1), and knockdown of SHIP1 greatly increased ROS production in BCG-infected macrophages. Collectively, these data indicate that miR-155 modulates ROS but not RNS production by targeting SHIP1, which may provide a better understanding of the host anti-mycobacterial response.     

Heme oxygenase and carbon monoxide initiate homeostatic signaling

Carbon monoxide (CO), a gaseous second messenger, arises in biological systems during the oxidative catabolism of heme by the heme oxygenase (HO) enzymes. Many biological functions of HO, such as regulation of vessel tone, smooth muscle cell proliferation, neurotransmission, and platelet aggregation, and anti-inflammatory and antiapoptotic effects have been attributed to its enzymatic product, CO. How can such diverse actions be achieved by a simple diatomic gas; can its protective effects be explained via regulation of a common signaling pathway? A number of the known signaling effects of CO depend on stimulation of soluble guanylate cyclase and/or activation of mitogen-activated protein kinases. The consequences of this activation remain unknown but appear to differ depending on cell type and circumstances. The majority of studies reporting a protective role of CO focus on pathways initiated by the pathological stimulus (e.g., lipopolysaccharide, hypoxia, balloon injury, tumor necrosis factor α, etc.) and its consequential modulation by CO. What has been less studied is the manner in which CO exposure alone modulates the molecular machinery of the cell so that a subsequent stress stimulus will elicit a homeostatic response as opposed to one that is chaotic and disordered. CO potentially interacts with other intracellular hemoprotein targets, although little is known about the functional significance of such interactions other then the known targets including mitochondrial oxidases, oxygen sensors, and nitric oxide synthases. The earliest response of a cell exposed to low concentrations of CO is clearly an increase in reactive oxygen species formation that we define as oxidative conditioning. This has important consequences for inflammation, proliferation, mitochondria biogenesis, and apoptosis. Within this review, we will highlight recent research on the molecular events underlying the physiologic effects of CO—which lead to cytoprotective conditioning.     

Nitric oxide and obstructive sleep apnea

Obstructive sleep apnea is a common disease, affecting 16% of the working age population. Although sleep apnea has a well-established connection to daytime sleepiness presumably mediated through repetitive sleep disruption, some other consequences are less well understood. Clinical, epidemiological, and physiological investigations have demonstrated a connection between sleep apnea and daytime hypertension. The elevation of arterial pressure is evident during waking, when patients are not hypoxic, and is mediated by sustained sympathoexcitation and by altered peripheral vascular reactivity. This review summarizes data suggesting that both the sympathoexcitation and the altered vascular reactivity are, at least in part, a consequence of reduced expression of nitric oxide synthase, in neural tissue and in endothelium. Reduced nitric oxide generation in central and peripheral sites of sympathoregulation and in endothelium together may, in part, explain the elevations in waking pressures observed in sleep apnea patients.     

Reactive oxygen species mediate compensatory glomerular hypertrophy in rat uninephrectomized kidney

Hyperfiltration in glomeruli is the most common pathway to progressive renal dysfunction. Moreover, reduction of renal mass by unilateral nephrectomy results in an immediate increase in glomerular flow to the remnant kidney, followed by compensatory glomerular hypertrophy. Reactive oxygen species (ROS) are involved in renal hypertrophic responses; however, the role of ROS in compensatory glomerular hypertrophy remains unclear. Therefore, this role was investigated in the present study. Wistar rats were randomly placed into two groups: uninephrectomized rats (Nx) and uninephrectomized rats treated with tempol (Nx + TP). The glomerular volume increased in the Nx 1 week after surgery, but was significantly suppressed in the Nx + TP. Levels of phospho-Akt and phospho-ribosomal protein S6, which are critical for cell growth and hypertrophy, were markedly increased in the glomeruli of the Nx, while tempol treatment almost abolished the activation of these proteins. These results suggest that ROS have important roles in compensatory hypertrophy in glomeruli. M. Ozeki and H. Nagasu have contributed equally to this study.     

一氧化氮和内质网应激

一氧化氮(nitric oxide,NO)是一种重要的多功能内源性气体分子,能舒张血管、参与免疫反应和作为一种神经递质在神经元的信息传递中发挥重要作用,因而广泛参与机体心血管系统、神经系统和免疫系统等的生理和病理调节[1].     

Dihydroartemisinin and transferrin dual-dressed nano-graphene oxide for a pH-triggered chemotherapy

Dihydroartemisinin (DHA) is a unique anti-malarial drug isolated from the plant Artemisia annua. Recently, it has been studied as an alternative modality for cancer therapy, utilizing its reactive oxygen species (ROS) yielding mechanism from interacting with Ferrous ion (Fe (Ⅱ)). In this work, a novel nanodrug (DHA-GO-Tf) is constructed based on nanoscale Graphene oxide (GO) dual-dressed with DHA and Transferrin (Tf). Tf dually functions as a pilot for the nanoparticle to target tumor cell with over expressed Transferrin receptor (TfR) and a ferric ion carrier. Upon tumor cellular endocytosis, Ferric ion (Fe(Ⅲ)) is released from the Tf, triggered by the low pH in the lysosomes of the tumor cell. The intracellular Fe (Ⅲ) is reduced to Fe (Ⅱ) and interacts with DHA to increase its cytotoxicity. The potential of this alternative anti-tumor modality is demonstrated both in vitro and in vivo. Comparing with DHA alone, the nanodrug DHA-GO-Tf resulted in a significantly enhanced tumor delivery specificity and cytotoxicity, and achieved a complete tumor cure in mice with minimal side-effects.     

Nitric oxide up-regulates the release of inflammatory mediators by mouse macrophages

Nitric oxide (NO) plays a key role in mediating macrophage cytotoxicity towards different targets, including tumoral cells and intracellular pathogens. However, its role in macrophage immunoregulation is less well defined. In this study, we have investigated the effect of altering NO levels on the production by mouse macrophages of cytokines, and reactive oxygen intermediates as measured by luminol-dependent chemiluminescence. Our results demonstrate that NO can enhance the release of both tumor necrosis factor-α and interleukin-1α, and chemiluminescence. Thus, in addition to acting as a powerful effector molecule in mediating cytotoxic activities of mouse macrophages, NO can play a role in enhancing the production of a variety of other inflammatory mediators, and thus can contribute both directly and indirectly to the immunopathology of macrophage-dependent inflammation.     

人类精液中一氧化氮和尿酸含量检测的关系

目的探讨人精液中一氧化氮(N0)与尿酸含量的关系,对精了质量的影响。方法参照WHO标准方法,进行精液常规分析,按精子密度、活动率不同分为(正常、<20、20~40、>40)4个组。采用镀铜镉还原荧光法检测NO代谢产物硝酸盐(NO3-)。采用尿酸酶一过氧化物酶偶联法检测精液尿酸含量。结果70例不育组精液中尿酸含量和NO含量为(236.4±47.8)μmol/L、(78.7±1.6)μmol/L与正常生育组(398.6±52.3)μmol/L、(41.84±1.6)μmol/L呈显著性差异(P<0.01)。将尿酸含量与NO含量进行相关性分析,两者呈显著性负相关(r=-0.96,P<0.05)。不育各精子密度和活动率组精液尿酸含量随精子密度及活动率增加而上升,N0含量随之下降(P<0.01),结论精液尿酸含量测定可作为评价精子受活性氧损害的重要指标,证明尿酸对活性氧尤其在医学领域极为重视的NO损害精子具有保护性作用。     

四逆汤对缺血-再灌注离体鼠肺的保护作用

目的： 建立离体大鼠肺灌流模型，研究四逆汤（SND）对缺血-再灌注肺的保护作用及可能机制。方法：将SD大鼠随机分成假手术组、模型组和模型+SND组，观察SND对大鼠肺组织形态学改变、平均肺动脉压（MPAP）、肺组织湿/干重比（W/D）、灌流液及肺组织匀浆中超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量以及肺组织匀浆中一氧化氮（NO）含量和一氧化氮合酶（NOS）活力的影响。结果：模型+SND组的肺泡壁增厚程度和肺泡水肿程度显著低于模型组，肺组织W/D值及MPAP显著小于模型组，灌流液和肺组织匀浆中SOD活性显著高于模型组，而MDA含量显著低于模型组。SND可显著抑制缺血-再灌注引起的肺组织NO含量的减少。但3组间比较，NOS含量无显著差异。结论：SND有抗大鼠肺缺血-再灌注损伤作用，其机制可能与清除氧自由基和改善组织灌流有关。     

七氟醚预处理对缺血再灌注大鼠心肌活性氧产生的影响及其发挥心肌保护作用的机制

目的: 观察七氟醚预处理对缺血再灌注大鼠心肌活性氧以及一氧化氮(NO)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPx)、过氧化氢酶(CAT)活性的影响,进一步探讨活性氧在七氟醚预处理减轻心肌缺血再灌注损伤中的作用。方法: 60只SD大鼠随机分为8组。在体用2%七氟醚预处理30 min 后结扎冠状动脉前降支30 min,然后再灌注120 min。以心肌梗死面积和凋亡指数反映心肌损伤情况,心肌梗死面积用氯化三苯基四氮唑染色显示,细胞凋亡用TUNEL染色显示。活性氧用活性氧荧光探针二氢乙啶测量。使用活性氧清除剂N-(2-巯基丙酰基)甘氨酸(2-MPG)以及一氧化氮合酶抑制剂N^ω-硝基-L-精氨酸甲酯(L-NAME)作为阻滞剂,用酶标仪测定心肌匀浆的NO、SOD、GPx和CAT活性,并进一步分析阻断活性氧及NO产生对七氟醚减轻心肌缺血再灌注损伤的影响。结果: 与对照组比较,七氟醚预处理在缺血再灌注前诱导活性氧产生(12.0±0.8 vs 2.6±0.5, P<0.05),在缺血再灌注后减少活性氧产生(16.2 ±0.9 vs 24.9±1.3, P<0.05);在缺血再灌注前,2-MPG减少七氟醚预处理心肌活性氧产生(5.1±0.7 vs 12.0±0.8, P<0.05),在缺血再灌注后2-MPG+七氟醚预处理组与缺血再灌注组比较无显著差别(24.9±1.4 vs 24.9±1.3, P>0.05);与对照组比较,七氟醚预处理同样诱导NO产生(34.5±3.2 vs 15.9±1.4, P<0.05),增加SOD(1.5±0.5 vs 0.6±0.2, P<0.05)、GPx(22.8±2.5 vs 12.7±2.2, P<0.05)和CAT(15.5±1.8 vs 11.2±1.4, P<0.05)的活性;2-MPG消除了七氟醚对NO、SOD、CPx和CAT的诱导作用和对缺血再灌注心肌的保护作用; L-NAME同样消除七氟醚预处理对SOD、GPx和CAT的诱导作用和心肌保护作用。结论: 七氟醚预处理减少心肌梗死面积和凋亡指数;七氟醚预处理产生的亚损伤量的活性氧和NO诱导缺血再灌注心肌SOD、GPx和CAT的产生,进而抑制缺血再灌注活性氧的产生和心肌损伤。     

Nitric oxide enhances cyclooxygenase activity in articular cartilage

Nitric oxide (NO) is a small messenger molecule synthesized by a family of enzymes, the nitric oxide synthases. Cyclooxygenases are a group of proinflammatory enzymes that release prostaglandins including prostaglandin E₂ (PGE₂). Both nitric oxide synthase and cyclooxygenase are involved in the inflammatory cascade of arthritis. However, the relationship between these two enzymes and their products has not been explored in articular cartilage. Here we show that in cultured bovine chondrocytes and explants of human osteoarthritic cartilage both nitric oxide synthase and cyclooxygenase activities were induced by the inflammatory mediators, lipopolysaccharide, and interleukin-1 or tumor necrosis factor-. When nitric oxide synthase activity was inhibited, PGE₂, synthesis was inhibited. NO donors also induced PGE₂ synthesis and NO scavengers inhibited cyclooxygenase activity. Taken together, these results support the concept that PGE₂ synthesis is directly related to NO formation and that NO may modulate cyclooxygenase activity in articular cartilage.accepted by W. B. van den BergFinalist in the 1995 Westinghouse Science Talent Search, the 1995 Otto Burgdorf Competition, and the 1995 St. Johns New York Symposium.     

活化补体诱生一氧化氮介导肝细胞损伤的实验研究

目的 探讨活化补体对大鼠枯否细胞（KC）分泌一氧化氮（NO）的影响及其与肝细胞损伤的关系。方法 大鼠KC＋肝细胞（HC）联合培养分别与酵母多糖活化人血清（ZAHS）,抗人C3、C5中和的ZAHS以及ZAHS＋氨基胍（iNOS抑制剂）作用后,观测培养上清中不同时相点的NO和乳酸脱氢酶（LDH）。结果 ZAHS作用组KC＋HC联合培养的上清中NO和LDH各时相点的测值显著升高（P＜0．01）;中和血清组和氨基胍组培养上清中NO分别下降53．4％－62．8％和68．1％－72．1％,LDH分别下降56．0％－66．5％和51．2％－57．2％,与作用组相差显著（P＜0．01）。结论 ZAHS中的C3、C5片断可激发KC生成NO、介导肝细胞损伤,这可能是某些病理情况下补体介导肝损伤的机制之一。