Copper and Zinc, Biological Role and Significance of Copper/Zinc Imbalance

铜和锌，铜/锌失衡的生物学作用和意义

1. UniversityMedical Center Ljubljana, Zaloska cesta 2, 1000 Ljubljana, Slovenia

2. GeneralHospital Izola, Polje40,6310 Izola, Slovenia

接上文

​The Studies about the Role of Copper and Zinc in Diseases 铜和锌在疾病中的作用研究

Immunological disorders 免疫系统疾病

The common cold: Researchers have hypothesized that zinc could reduce the severity and duration of cold symptoms by directly inhibiting rhinovirus binding and replication in the nasal mucosa and suppressing inflammation [156]. Although studies examining the effect of zinc treatment on cold symptoms have had somewhat conflicting results, overall zinc appears to be beneficial under certain circumstances. In a randomized, double-blind, placebo-controlled clinical trial, 50 subjects (within 24 hours of developing the common cold) took a zinc acetate lozenge (13.3 mg zinc) or placebo every 2–3 wakeful hours. Compared with placebo, zinc lozenges significantly reduced the duration of cold symptoms (cough, nasal discharge, and muscle aches) [157]. In another clinical trial involving 273 participants with experimentally induced colds, zinc gluconate lozenges significantly reduced the duration of illness compared with placebo but had no effect on symptom severity [158]. In 2007, Caruso and colleagues published a structured review of the effects of zinc lozenges, nasal sprays, and nasal gels on the common cold. Of the 14 randomized, placebo-controlled studies included, 7 showed that the zinc treatment had a beneficial effect and 7 showed no effect [159]. A Cochrane review concluded that zinc (lozenges or syrup) is beneficial in reducing the duration and severity of the common cold in healthy people, when taken within 24 hours of onset of symptoms [160]. Recently (in August 2011), in the meta-analysis all of the identified placebo-controlled trials, included in MEDLINE, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) databases, were analysed together. The study shows strong evidence that the zinc lozenge effect on common cold duration is heterogeneous so that benefit is observed with high doses of zinc but not with low doses: a total daily zinc dose of less than 75 mg found no effect on common cold duration, whereas using zinc acetate in daily doses exceeding 75 mg showed a 42% reduction in the duration of colds and using zinc salts other than acetate in daily doses exceeding 75 mg showed a 20% reduction in the duration of colds. The effects of zinc lozenges should be further studied to determine the optimal lozenge compositions and treatment strategies [161]. Numerous case reports of anosmia, in some cases long-lasting or permanent, from the use of zinc-containing nasal gels or sprays (but only in these forms) raise questions about the safety of intranasal zinc [162, 163]. In June 2009, the FDA warned consumers to stop using three zinc-containing intranasal products because they might cause anosmia [164]. On the basis of the long-term studies with high zinc doses, mentioned before, there does not seem to be any basis for assuming that treating the common cold for a week with high doses of zinc in the form of lozenges would cause unanticipated harm. A patient suffering from acute adverse effects such as bad taste can simply stop taking the lozenges [161].

普通感冒：研究人员假设锌可以通过直接抑制鼻病毒在鼻粘膜中的结合和复制以及抑制炎症来减轻感冒症状的严重程度和持续时间 [156]。尽管研究锌治疗对感冒症状的影响的研究结果有些矛盾，但在某些情况下，整体锌似乎是有益的。在一项随机、双盲、安慰剂对照的临床试验中，50名受试者（在患上普通感冒24小时内）每2-3个清醒小时服用一次醋酸锌锭剂（13.3 mg锌）或安慰剂。与安慰剂相比，锌含片显著缩短感冒症状（咳嗽、流鼻涕和肌肉疼痛）的持续时间 [157]。在另一项涉及273名实验性感冒参与者的临床试验中，与安慰剂相比，葡萄糖酸锌锭剂显著缩短了病程，但对症状严重程度没有影响 [158]。2007年，Caruso及其同事发表了一篇关于锌锭剂、鼻喷雾剂和鼻凝胶对普通感冒影响的结构化综述。在纳入的14项随机、安慰剂对照研究中，7项显示锌治疗具有有益效果，7项显示无效果 [159]。一项Cochrane综述得出结论，在症状出现后24小时内服用锌（锭剂或糖浆）有益于减少健康人普通感冒的持续时间和严重程度 [160]。最近（2011年8月），在荟萃分析中，对MEDLINE、Scopus和Cochrane对照实验中心数据库中所有已确定的安慰剂对照试验进行了分析。研究表明，锌锭剂对感冒持续时间的影响是异质的，因此在高剂量锌而不是低剂量时观察到有益效果：每日总锌剂量低于75毫克发现对普通感冒持续时间没有影响，而在每日剂量超过75毫克的情况下使用醋酸锌显示感冒持续时间减少42%，而在每日剂量超过75毫克的情况下使用醋酸锌以外的锌盐显示感冒持续时间减少20%。应进一步研究锌锭剂的作用，以确定最佳锭剂成分和治疗策略 [161]。大量因使用含锌鼻凝胶或喷雾剂（但仅限于这些形式）导致嗅觉丧失的病例报告，在某些情况下是长期或永久性的，这引发了对鼻内锌的安全性的质疑 [162, 163]。2009年6月，FDA警告消费者停止使用三种含锌的鼻内产品，因为它们可能导致嗅觉丧失 [164]。基于之前提到的高剂量锌的长期研究似乎没有任何依据可以假设用高剂量的锌锭剂治疗普通感冒一周会造成意想不到的伤害。患有急性不良反应（例如味觉不好）的患者可以停止服用锭剂 [161]。

Arterial and venous leg ulcers: Zinc helps maintain the integrity of skin and mucosal membranes [105]. Patients with chronic leg ulcers have abnormal zinc metabolism and low serum zinc levels [165]. Clinicians frequently treat skin ulcers with zinc supplements [166]. The authors of a systematic review concluded that zinc sulfate might be effective for treating leg ulcers in some patients who have low serum zinc level, but it is not effective in the general use in patients with chronic leg ulcers, arterial or venous ulcers [167,168].

腿部动脉和静脉溃疡：锌有助于维持皮肤和粘膜的完整性 [105]。慢性腿部溃疡患者的锌代谢异常和血清锌水平低 [165]。临床医生经常使用锌补充剂治疗皮肤溃疡 [166]。一项系统评价的作者得出结论，硫酸锌可能对治疗一些低血清锌水平患者的腿部溃疡有效，但在慢性腿部溃疡、动脉或静脉溃疡患者的一般使用中无效 [167,168]。

Wound healing: Copper plays a major role in wound healing. Scientists think that introducing copper into wound dressings would not only reduce the risk of wound and dressing contamination, but also stimulate faster healing. Releasing copper from the dressings directly onto the wound promotes skin regeneration [169].

伤口愈合：铜在伤口愈合中起主要作用。科学家们认为，将铜引入伤口敷料不仅可以降低伤口和敷料污染的风险，还可以促进更快的愈合。将敷料中的铜直接释放到伤口上可促进皮肤再生 [169]。

Burns: When skin is burned, a substantial percentage of micronutrients, such as copper, selenium, and zinc may be lost. This increases the risk for infection, slows the healing process, prolongs the hospital stay, and even increases the risk of death. However, people with major burns tend to lose copper more rapidly than other minerals. Although it is unclear which micronutrients are most beneficial for people with burns, many clinical studies suggest that a multivitamin including copper and other minerals may aid in the recovery process [170].

烧伤：当皮肤被烧伤时，可能会损失大量的微量营养素，例如铜、硒和锌。这增加了感染的风险，减缓了愈合过程，延长了住院时间，甚至增加了死亡的风险。然而，严重烧伤的人往往比其他矿物质更快地失去铜。虽然尚不清楚哪种微量营养素对烧伤患者最有益，但许多临床研究表明，包括铜和其他矿物质在内的多种维生素可能有助于恢复过程 [170]。

Immunological disorders on animal models: Another study shows that copper deficiency in mice impairs immune system function. Dietary copper was restricted in mice during five discrete intervals over a 9 week period of perinatal development: gestation only (G), lactation only (L), 3 week postlactation (PL), 1 week after birth through postlactation (2/3L + PL), and lactation plus postlactation (L + PL). Signs of severe copper deficiency, such as low liver copper levels, and significant reductions in activity of plasma ceruloplasmin and splenocyte Cu/Zn superoxide dismutase were most evident in 6-weekold mice from two groups, -Cu 2/3L + PL and -Cu L + PL. Mice in these groups were anemic and had small thymuses and enlarged spleens compared to controls receiving +Cu treatment. The -Cu mice demonstrated impaired antibody - plaque-forming cells response (PFC) to sheep erythrocytes, and the attenuation was proportional to copper deficiency, as judged by liver copper levels. Total plasma IgM levels were not greatly altered by -Cu treatment except in model L + PL. Total IgG levels were markedly reduced in this group and in the –Cu 2/3L + PL group. The PFC response of mice in the -Cu PL group was normal even though signs of copper deficiency were evident; however, the PFC response was reduced when -Cu treatment was extended to 5 weeks, and was reversible by switching to +Cu treatment. It is evident that severity of copper deficiency in mice is related to degree of impaired immunity. Furthermore, severity of copper deficiency is dependent on duration and time of initiation of dietary copper restriction [171].

动物模型的免疫系统疾病：另一项研究表明，小鼠缺铜会损害免疫系统功能。在9周的围产期发育期间，小鼠在五个离散的时间间隔内限制膳食铜：仅妊娠（G）、仅哺乳期（L）、哺乳后3周（PL）、出生后1周至哺乳后（2/3L+PL），以及泌乳加泌乳后 (L+PL)。严重铜缺乏的迹象，例如低肝铜水平，以及血浆铜蓝蛋白和脾细胞铜/锌超氧化物歧化酶活性显著降低，在来自两组的6周龄小鼠中最为明显，-Cu 2/3L+P和-Cu L+PL。与接受+Cu治疗的对照组相比，这些组中的小鼠贫血，胸腺小，脾脏肿大。-Cu小鼠表现出对绵羊红细胞的抗体-空斑形成细胞反应（PFC）受损，并且衰减与铜缺乏成比例，这通过肝铜水平来判断。除模型L+PL外，-Cu处理未显著改变总血浆IgM水平。该组和–Cu 2/3L+PL组的总IgG水平显著降低。-Cu PL组小鼠的PFC反应正常，尽管缺铜迹象很明显；然而，当-Cu治疗延长至5周时，PFC反应降低，并且通过切换到+Cu治疗是可逆的。显然，小鼠缺铜的严重程度与免疫力受损程度有关。此外，铜缺乏的严重程度取决于持续时间和饮食中开始限制铜的时间 [171]。

In the next study, the effects of severe, moderate, and mild copper deficiencies on cellular and humoral immunity of fifty male rats were studied. All rats were immunized once with sheep red blood cells. Mean plasma-copper concentration reflected the dietary levels of copper, and ceruloplasmin activity correlated highly to plasma copper. Rats consuming suboptimal levels of copper responded differently to the deficiencies, so copper status varied among those animals. After 8 weeks, cell proliferation, when stimulated by phytohemagglutinin, was dependent on the copper status of the animal. Severely deficient rats had consistently lower lymphocyte stimulation indexes for phytohemagglutinin, but specific antibody response was not reduced. ImmunoglobulinG concentrations were variable for all rats, and immunoglobulin M concentrations were lower for the severely deficient rats [172].

在接下来的研究中，研究了重度、中度和轻度铜缺乏50只雄性大鼠的细胞和体液免疫的影响。所有大鼠均用绵羊红细胞免疫一次。平均血浆铜浓度反映了铜的膳食水平，铜蓝蛋白活性与血浆铜高度相关。大鼠对铜的消耗水平不同，因此这些动物的铜状态各不相同。8周后，受植物血凝素刺激的细胞增殖取决于动物的铜状态。严重缺乏的大鼠对植物血凝素的淋巴细胞刺激指数始终较低，但特异性抗体反应并未降低。所有大鼠的免疫球蛋白G浓度各不相同，严重缺乏大鼠的免疫球蛋白M浓度较低 [172]。

The role of Cu/ZnSOD1 in oxidative stress 铜/锌超氧化物歧化酶1在氧化应激中的作用

Detailed studies in the past two decades have shown that redox active metals like iron, copper, chromium, cobalt and other metals undergo redox cycling reactions and possess the ability to produce reactive radicals such as superoxide anion radical and nitric oxide in biological systems. Disruption of metal ion homeostasis may lead to oxidative stress, a state where increased formation of reactive oxygen species overwhelms body antioxidant protection and subsequently induces DNA damage, lipid peroxidation, protein modification and other effects, all symptomatic for numerous diseases, involving cancer, cardiovascular disease, diabetes, atherosclerosis, neurological disorders, chronic inflammation and others. A special position among metals is occupied by the redox inert metal zinc. Zn is an essential component of numerous proteins involved in the defense against oxidative stress. It has been shown, that depletion of Zn may enhance DNA damage via impairments of DNA repair mechanisms. In addition, Zn has an impact on the immune system and possesses neuroprotective properties. The mechanism of metal-induced formation of free radicals is tightly influenced by the action of cellular antioxidants. Besides the encymes (SOD, catalase), many low-molecular weight antioxidants (ascorbic acid, alpha-tocopherol, glutathione, carotenoids, flavonoids, and other antioxidants) are capable of chelating metal ions reducing their catalytic activity to form reactive oxygen species [173]. In the study designed to assess the antioxidant status and erythrocyte oxidative injuries in Iranian fat-tailed sheep that suffered from malignant theileriosis, blood samples were taken and hematological parameters, the activities of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase, erythrocyte osmotic fragility, and serum concentrations of some trace elements (copper, iron, zinc, manganese, and selenium), were measured. As an index of lipid peroxidation, the level of malondialdehyde (MDA) was also determined. According to the results, a significant decrease in red blood cell count, packed cell volume, the activities of SOD, GPX, and catalase (p<0.001), and also serum concentrations of Cu, Zn, Mn, and Se (p<0.05) were evident in the infected sheep. Significantly increased levels of MDA and erythrocyte osmotic fragility (p<0.001) as well as serum concentration of iron (p<0.05) were recorded in the infected animals. The significant decrease in antioxidant enzyme activities and substantial elevated levels of lipid peroxidation and erythrocyte osmotic fragility associated with the increase in parasitemia indicate increased exposure of red blood cells to oxidative stress. It appeared that disturbed antioxidant defense mechanisms can promote the development of anemia in ovine theileriosis [174].

过去二十年的详细研究表明，铁、铜、铬、钴等氧化还原活性金属会发生氧化还原循环反应，并具有产生生物系统中的活性自由基，如超氧阴离子自由基和一氧化氮。金属离子稳态的破坏可能会导致氧化应激，在这种状态下，活性氧的形成会破坏身体的抗氧化保护，并随后引起DNA损伤、脂质过氧化、蛋白质修饰和其他影响，这些都是许多疾病的症状，包括癌症、心血管疾病、糖尿病、动脉粥样硬化、神经系统疾病、慢性炎症等。金属中的一个特殊位置是氧化还原惰性金属锌。锌是参与防御氧化应激的许多蛋白质的重要组成部分。已经表明，锌的消耗可能会通过损害DNA修复机制来增强DNA损伤。此外，锌对免疫系统有影响，并具有神经保护作用。金属诱导自由基形成的机制受到细胞抗氧化剂作用的密切影响。除了酶（SOD、过氧化氢酶），许多低分子量抗氧化剂（抗坏血酸、α-生育酚、谷胱甘肽、类胡萝卜素、类黄酮和其他抗氧化剂）能够螯合金属离子，降低其催化活性以形成活性氧 [173]。在旨在评估患有恶性泰勒病的伊朗肥尾羊的抗氧化状态和红细胞氧化损伤的研究中，采集了血液样本和血液学参数，包括超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GPX）在内的抗氧化酶的活性测定了过氧化氢酶、红细胞渗透脆性和一些微量元素（铜、铁、锌、锰和硒）的血清浓度。作为脂质过氧化的指标，还测定了丙二醛（MDA）的水平。结果显示，红细胞计数、红细胞压积、SOD、GPX和过氧化氢酶活性显著降低（p<0.001），血清铜、锌、锰和硒浓度显著降低（p<0.05）在受感染的绵羊中很明显。在受感染的动物中记录了显著增加的MDA和红细胞渗透脆性（p<0.001）以及血清铁浓度 （p<0.05）。与寄生虫血症增加相关的抗氧化酶活性显著降低以及脂质过氧化水平和红细胞渗透脆性显著升高表明红细胞暴露于氧化应激增加。似乎受干扰的抗氧化防御机制可以促进绵羊泰勒病中贫血的发展 [174]。

In another study, of Cu/Zn imbalance in rats, the scientists determined the content of copper in blood, the activity of superoxide dismutase (SOD), and the content of malondialdehyde (MDA) to analyse the relations among the copper concentration, the copper-zinc ratio (Cu/Zn) and the biomarkers of lipid peroxidation (MDA), by controlling the level of copper intake in copper deficiency rats. In the status of copper deficiency, the SOD activity was lower than the normal level, and then presented a rise trend with the increased of copper intake that is, the ratio of copper-zinc (Cu/Zn). The content of MDA was higher than the normal level in Cu deficiency rats and the content of MDA decreased with the increasing of copper intake and the Cu/Zn ratio, and maintained at a relatively low level [175].

在另一项关于大鼠铜/锌失衡的研究中，科学家们测定了血液中铜的含量、超氧化物歧化酶（SOD）的活性和丙二醛（MDA）的含量，以分析铜浓度、铜之间的关系。铜/锌比率（Cu/Zn）和脂质过氧化（MDA）的生物标志物，通过控制铜缺乏大鼠的铜摄入水平。在缺铜状态下，SOD活性低于正常水平，然后随着铜摄入量的增加呈现上升趋势，即铜锌比（Cu/Zn）。缺铜大鼠MDA含量高于正常水平，随着铜摄入量和铜/锌比的增加，MDA含量降低，并保持在较低水平 [175]。

Developmental disorders 发育障碍

The studies show that zinc deficiency during early development can result in multiple brain abnormalities and altered neuronal functions [25,96]. In rats, a gestational deficit of Zn can affect the rat fetal brain cytoskeleton and signaling cascades involved in cellular processes that are central to brain development. Scientists tested the hypothesis that oxidative stress is involved in Zn deficiency-induced altered tubulin dynamics and the associated dysregulation of transcription factor [NF-κB] in rat cortical neurons in animal model of Zn deficiency. A low rate of in vitro tubulin polymerization, an increase in tubulin oligomers, and a higher protein cysteine oxidation were observed in the Zn-deficient neuronal cells. In this animal model of Zn deficiency the conclusion was that a deficit in Zn viability could affect early brain development through: an induction of oxidative stress, tubulin oxidation, altered tubulin dynamics and deregulation of signals (NF-κB) involved in critical developmental events [176]. In another study, rat embryos were fed with Cu-adequate (8 micrograms Cu/g) or Cu-deficient (<0.5 micrograms Cu/g) diet and were cultured in Cu-adequate (16.2 microM) or Cu-deficient (1.0 microM) rat serum. Control embryos cultured in control serum were morphologically normal. Cu-deficient embryos developed abnormally when cultured in Cu-deficient serum; the abnormalities included distended hind brains, blisters, blood pooling, and cardiac defects. Control embryos cultured in Cu-deficient serum and Cu-deficient embryos cultured in control serum also showed abnormal development, but to a lesser degree than that of the Cu-deficient embryos cultured in Cu-deficient serum. To test the idea that the above abnormalities were due in part to free radical induced damage occurring secondary to an impaired oxidant defense system, a chemiluminescence assay was used to detect superoxide dismutase (SOD) activity in the cultured embryos. SOD activity was lowest in embryos cultured in Cu-deficient serum. When the Cu-deficient serum was supplemented with antioxidants (Cu/ZnSOD or glutathione peroxidase), its teratogenicity was reduced. These data support the idea that an impaired oxidant defense system contributes to the dysmorphology associated with Cu deficiency. However, the Cu-deficient embryos also had low cytochrome c oxidase activity compared to control embryos - thus, multiple factors are likely contributing to Cu deficiency induced abnormalities [177].

研究表明，早期发育过程中缺锌会导致多种大脑异常和神经元功能改变 [25,96]。在大鼠中，妊娠期锌缺乏会影响大鼠胎儿脑细胞骨架和信号级联反应，这些级联反应涉及对大脑发育至关重要的细胞过程。科学家们检验了氧化应激与缺锌诱导的微管蛋白动力学改变和相关的转录因子失调有关的缺锌动物模型大鼠皮层神经元中的 [NF-κB]。在缺锌的神经元细胞中观察到低速率的体外微管蛋白聚合、微管蛋白寡聚体的增加和较高的蛋白质半胱氨酸氧化。在这个缺锌动物模型中，结论是锌活力不足可能通过以下方式影响早期大脑发育：诱导氧化应激、微管蛋白氧化、改变微管蛋白动力学和参与关键发育事件的信号失调（NF-κB） [176]。在另一项研究中，大鼠胚胎饲喂铜充足（8微克铜/克）或铜缺乏（<0.5微克铜/克）饮食，并在铜充足（16.2microM）或铜缺乏（1.0microM）中培养大鼠血清。在对照血清中培养的对照胚胎形态正常。在缺铜血清中培养时，缺铜胚胎发育异常；异常包括后脑膨胀、水泡、血池和心脏缺陷。在缺铜血清中培养的对照胚胎和在对照血清中培养的缺铜胚胎也表现出异常发育，但程度低于在缺铜血清中培养的缺铜胚胎。为了验证上述异常部分是由于继发于氧化防御系统受损而引起的自由基诱导损伤的想法，使用化学发光测定法检测培养胚胎中的超氧化物歧化酶（SOD）活性。在缺铜血清中培养的胚胎中SOD活性最低。当缺铜血清补充抗氧化剂（铜/锌超氧化物歧化酶或谷胱甘肽过氧化物酶）时，其致畸性降低。这些数据支持这样一种观点，即受损的氧化防御系统会导致与铜缺乏相关的畸形。然而，与对照胚胎相比，缺乏铜的胚胎也具有较低的细胞色素C氧化酶活性-因此，多种因素可能导致铜缺乏诱导的异常 [177]。

The Studies of Cu/Zn imbalance in neurological disorders 神经系统疾病中铜/锌失衡的研究

The highest levels of zinc are found in the hippocampus in synaptic vesicles, boutons, and mossy fibers. Zinc is also found in large concentrations in the choroid layer of the retina. Zinc plays an important role in axonal and synaptic transmission and is necessary for nucleic acid metabolism and brain tubulin growth and phosphorylation. Lack of zinc has been implicated in impaired DNA, RNA, and protein synthesis during brain development. For these reasons, deficiency of zinc during pregnancy and lactation has been shown to be related to many congenital abnormalities of the nervous system. Furthermore, in children insufficient levels of zinc have been associated with lowered learning ability, apathy, lethargy, and mental retardation. Children with attention deficit disorder may be deficient in zinc and vitamin B-6 and have an excess of lead and copper. Alcoholism, schizophrenia, Wilson's disease, and Pick's disease are brain disorders dynamically related to zinc levels. Zinc has been employed with success to treat Wilson's disease, achrodermatitis enteropathica, and specific types of schizophrenia [3].

最高水平的锌存在于海马的突触小泡、突触子和苔藓纤维中。在视网膜的脉络膜层中也发现了高浓度的锌。锌在轴突和突触传递中起重要作用，是核酸代谢和脑微管蛋白生长和磷酸化所必需的。缺乏锌与大脑发育过程中 DNA、RNA和蛋白质合成受损有关。由于这些原因，孕期和哺乳期缺锌已被证明与许多先天性神经系统异常有关。此外，在儿童中，锌水平不足与学习能力下降、冷漠、嗜睡和智力迟钝有关。患有注意力缺陷障碍的儿童可能缺乏锌和维生素B-6，并且铅和铜含量过多。酗酒、精神分裂症、Wilson’s氏病和皮克氏病是与锌水平动态相关的脑部疾病。锌已成功用于治疗Wilson’s氏病、肠病性软皮炎和特定类型的精神分裂症 [3]。

接下文Part.2