铁死亡的发生机制及在肝脏疾病中的作用

铁死亡是新近发现的一种铁依赖性、脂质过氧化物集聚导致的调节性细胞死亡,其形态学特征为线粒体体积缩小、膜密度增加和线粒体减少或消失。发生机制主要与铁代谢紊乱、氨基酸抗氧化系统失衡、脂质过氧化物集聚有关。研究显示,铁死亡在不同的肝脏疾病背景下扮演不同角色,铁死亡的发生可参与多种肝脏炎症疾病进展,也可抑制肝纤维化形成、肝癌发生及索拉非尼耐药。总结了铁死亡发生机制及其在肝脏疾病中的作用和进展,旨在为肝脏疾病的进一步研究与治疗提供参考。     

肝脏疾病细胞铁死亡研究进展*

目的 铁死亡是一种新发现的细胞死亡方式,是由于细胞内铁离子水平异常升高,导致氧化还原失衡,细胞膜发生脂质过氧化,最终细胞膜破裂,导致细胞死亡。目前认为铁死亡的中心环节是铁代谢和活性氧代谢。铁死亡可以影响多种疾病的发生发展过程,例如神经退行性疾病、肿瘤、缺血再灌注损伤、免疫性疾病等。越来越多的研究表明,在多种肝脏疾病的发生发展过程中均出现不同程度的铁超载和脂质活性氧堆积等铁死亡特征。铁死亡可以通过调节细胞内铁离子水平和脂质过氧化程度影响肝脏疾病的进程。本文将针对肝脏疾病发病过程中细胞铁死亡研究进展进行综述。     

铁死亡在缺血性中风中的作用及中医药干预的研究进展

综述缺血性中风铁死亡的发生机制及中医药干预的研究进展,为缺血性中风的预防和治疗提供新的理论依据及策略。铁死亡是近年来研究发现的一种全新的细胞程序性死亡方式,是一种因铁依赖性的脂质过氧化物积累引起细胞死亡的调节形式。近年来,对铁死亡这一以铁依赖性脂质过氧化积累为特征的调节性细胞死亡与中风关系的研究越来越多,铁死亡的发生导致机体正常的组织器官损伤或功能丧失,这一过程直接参与疾病的发生、发展与转归。因此,针对缺血性中风,抑制铁死亡的发生可以有效地预防及延缓缺血导致的脑组织损伤。一些中药提取物及中药复方均可抑制铁死亡,起到神经保护作用。     

糖尿病并发症中铁死亡相关治疗靶点的研究进展

铁死亡是一种因脂质过氧化物过量堆积引起的铁依赖性、非凋亡形式的调节性细胞死亡, 其整体上由氧化和抗氧化系统控制。许多代谢途径通过直接或间接调节铁的累积或脂质过氧化来协调铁死亡, 在癌症、炎症性疾病和糖尿病等多种涉及铁或活性氧的疾病中均发现了铁死亡的影响。多项研究表明, 铁死亡参与了糖尿病及糖尿病并发症的进展过程, 其机制包括铁过载和脂质过氧化物清除能力的损害等, 通过对铁死亡的抑制, 可以有效改善疾病的进展, 这使得调节铁死亡成为治疗相关疾病的潜在方向。该文就铁死亡在糖尿病并发症中的调节机制, 尤其是其潜在的治疗靶点进行了综述, 以期为治疗糖尿病及其并发症提供新的思路。     

铁死亡在高血压发病中的作用

铁死亡是一种新发现的铁依赖性的细胞程序性死亡方式,主要特征为细胞内铁超载、谷胱甘肽耗竭及脂质过氧化。高血压是心脑血管疾病发生的重要危险因素之一,越来越多的研究证明高血压与铁死亡密切相关。本文将综述铁死亡与高血压之间的联系,以及铁死亡影响高血压的相关可能机制,以期为高血压的治疗提供新的思路。     

铁死亡的发生机制及其在非酒精性脂肪性肝病/非酒精性脂肪性肝炎发生发展中的作用

铁死亡是脂质过氧化驱动、铁依赖的细胞死亡。发生机制与铁稳态失衡、脂质过氧化及SLC7A11-GSH-GPX4抗氧化系统有关。在非酒精性脂肪性肝病(NAFLD)/非酒精性脂肪性肝炎(NASH)的发生发展中发挥关键作用。抑制铁死亡,几乎可以完全抑制NASH发生。通过对铁死亡发生机制及其在NAFLD/NASH疾病中的作用和进展进行综述,并提出铁死亡研究的策略和技术手段,以期为NAFLD/NASH机制研究提供参考。     

肝脏相关疾病发生发展中的铁超载

铁是人体内必不可少的一种金属元素，调节着体内多种酶的活性。铁代谢稳态的维持对于正常生理过程的进行意义重大，当机体发生铁超载时脂质过氧化增强、活性氧大量增加，引发细胞毒性甚至细胞死亡，进而导致组织器官功能障碍。随着对铁死亡研究的深入，发现铁超载介导铁死亡在多种肝病的发生发展中发挥重要作用，本文就铁超载在肝脏相关疾病发生发展的作用的研究进展作一综述。     

铁死亡治疗肝脏疾病的新机会

铁死亡是由Dixon于2012年发现的一种新型的细胞死亡形式，其有异于目前发现的其他细胞死亡方式，并犹如一把双刃剑在不同疾病层面发挥着不同的生物学效应。越来越多研究表明，铁死亡发生在各类急慢性肝病的发病、转归、预后等各个方面，所以了解铁死亡有利于明晰更多肝脏疾病的发病机制，而靶向调控铁死亡将有望成为治疗各类肝脏疾病的奠基石。我们通过查阅中外文献数据库，概述铁死亡独特的细胞死亡机制及其相关影响信号和通路，并介绍在各类急慢性肝病中铁死亡可能性的切入机制和靶点，为铁死亡在肝脏疾病中的应用和研究提供科学依据。     

膀胱癌发病过程中细胞铁死亡的调控机制及其靶向治疗研究进展

铁死亡是一种铁依赖性的脂质过氧化介导的细胞死亡方式，主要特点是细胞内铁和脂质过氧化物的过度积累。铁死亡在肿瘤生长抑制及肿瘤免疫微环境中发挥重要作用。研究发现，铁死亡与膀胱癌的发生发展有关。增加细胞内铁离子、抑制SLC7A11表达、激活p53等可诱导膀胱癌细胞铁死亡，非编码RNA对铁死亡也有一定调控作用。靶向某些铁死亡相关基因或应用某些化合物，能诱导铁死亡，减轻膀胱癌对化疗药物的耐药。深入研究铁死亡作用机制及相关作用靶点，有望开发新的膀胱癌靶向治疗方法，提高治疗效果，改善患者预后。     

铁代谢和铁死亡及其对阿尔茨海默病影响的研究进展

<正>阿尔茨海默病(Alzheimer.sdisease,AD)是一种多发于高龄人群、起病不易察觉、症状呈进行性加重的神经疾病。其发病机制有多重学说。铁死亡是一种区别于以往发现的细胞死亡形式,主要是由于细胞内具有高度氧化活性的二价铁离子增多,发生芬顿反应,抗氧化平衡被打破导致活性氧和有毒脂质过氧化物堆积,最终导致细胞死亡。过程中主要涉及铁代谢、氨基酸代谢及脂质代谢。其中铁代谢失衡引起的铁死亡与AD关系密切。我们将对铁代谢引发铁死亡的机制及其对AD特征性病理进程的影响进行综述。     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Serological survey of HIV and syphilis in pregnant women in Madagascar

Objectives Peripartal transmission of human immunodeficiency virus (HIV) and Treponema pallidum, the causative agent of syphilis, leads to severe consequences for newborns. Preventive measures require awareness of the maternal infection. Although HIV and syphilis testing in Madagascar could be theoretically carried out within the framework of the national pregnancy follow‐up scheme, the required test kits are rarely available at peripheral health centres. In this study, we screened blood samples of pregnant Madagascan women for HIV and syphilis seroprevalence to estimate the demand for systemic screening in pregnancy. Methods Retrospective anonymous serological analysis for HIV and syphilis was performed in plasma samples from 1232 pregnant women that were taken between May and July 2010 in Ambositra, Ifanadiana, Manakara, Mananjary, Moramanga and Tsiroanomandidy (Madagascar) during pregnancy follow‐up. Screening was based on Treponema pallidum haemagglutination tests for syphilis and rapid tests for HIV, with confirmation of positive screening results on line assays. Results Out of 1232 pregnant women, none were seropositive for HIV and 37 (3%) were seropositive for Treponema pallidum. Conclusions Our findings are in line with previous studies that describe considerable syphilis prevalence in the rural Madagascan population. The results suggest a need for screening to prevent peripartal Treponema pallidum transmission, while HIV is still rare. If they are known, Treponema pallidum infections can be easily, safely and inexpensively treated even in pregnancy to reduce the risk of transmission.