自噬在青光眼发病机制中的研究进展

青光眼是一组以视网膜神经节细胞(RGCs)渐进性死亡及其轴突慢性退化为特征的神经退行性疾病,主要与病理性眼压升高有关。自噬,即细胞自我"消化",是一种细胞降解、回收机制。过度自噬或自噬受损均可能导致细胞功能障碍,甚至死亡。近年的研究表明,自噬与不同因素导致的青光眼小梁网细胞功能异常和RGCs凋亡及视神经退行性改变密切相...     

自噬与青光眼关系的研究进展

自噬是溶酶体降解或再循环利用细胞器、蛋白质等胞内物质成分的过程,在细胞内环境稳态中发挥重要作用.近年来的研究表明,自噬与众多眼病包括青光眼的发生和发展有着密切联系.自噬可能是导致小梁网细胞功能异常的重要因素之一,其对视网膜神经节细胞发挥保护作用还是促进其死亡,仍存在争议.目前与青光眼有关的自噬基因的研究主要是OPTN基因,其编码的蛋白质optineurin与正常眼压性青光眼的发生发展相关.通过调控自噬而保护视网膜神经节细胞免于损伤可能是青光眼视神经保护的一种新方法.     

氧化应激对小梁网的损伤

青光跟是一组以视网膜神经节细胞(RGCs)丢失和视野缺损为特征的神经退行性疾病,其病理机制尚不完全清楚,眼压升高被认为是青光眼发生和发展最主要的危险因素.小梁网及Schlemm管是房水引流系统的主要组成部分,其结构或功能异常可引起房水流出的受阻进而引起眼压升高.越来越多的证据表明,氧化损伤可能在人小梁网细胞凋亡、功能障碍及其他退行性改变过程中发挥作用.氧化损伤是体内氧化和抗氧化失衡,从而引起脂质过氧化反应、蛋白质变性、DNA损伤等一系列组织病理损伤的过程.既往研究发现青光眼患者房水中氧化应激标志物水平升高,且氧化应激可引起小梁网细胞DNA氧化损伤、细胞内线粒体氧化损伤和炎症反应.本文就氧化应激在小梁网功能损伤中发挥的作用及可能的机制进行综述.     

非编码RNA调控小梁网组织在青光眼中作用的研究进展

小梁网是前房水引流的重要通道,呈复杂的三维结构,主要的细胞成分是小梁网细胞,细胞之间有交错成多层的细胞外基质。小梁网结构和功能的改变是导致眼压失常甚至视神经损伤的重要原因。有研究发现,非编码RNA(ncRNA)的异常表达可导致小梁网细胞生存率、收缩性能和细胞外基质结构发生改变,房水流出受阻,眼压失控,是青光眼发生的重要机制。目前,与小梁网相关的ncRNA研究涉及多种ncRNA分子和多种类型青光眼,本文将对微小RNA、长链ncRNA和环状RNA等ncRNA在小梁网组织中的研究进展进行综述。     

原花青素对H2O2诱导人小梁细胞氧化应激的抗氧化作用

目的 研究原花青素(Procyanidins,PC)对H2O2诱导人眼小梁细胞(human trabecular meshwork cells,HTMC)氧化应激的抗氧化作用,为青光眼的临床治疗提供实验依据.方法 将正常HTMC进行细胞传代后随机分为5组.未处理组:正常培养的HTMC;对照组:正常培养的HTMC+ H2O2(500 μmol·L-1处理1h);PC组:正常培养的HTMC+ H2O2(500 μmol·L-1处理1h) +PC(浓度分别为0.02 g·L-1、0.05 g· L-1、0.10 g· L-1).应用实时荧光定量PCR方法检测线粒体复合物Ⅰ mRNA的表达.结果 与未处理组(1.000 0±0.000 0)相比,0.02 g· L-1 PC组(0.401 3±0.010 3)和0.05 g· L-1 PC组(0.791 5±0.008 5)线粒体复合物Ⅰ mRNA表达差异有统计学意义(均为P＜0.01),而0.10g·L-1 PC组(1.043 0 ±0.062 2)差异无统计学意义(P＞0.05);与对照组(0.095 0±0.006 5)相比,各PC处理组线粒体复合物Ⅰ mRNA表达均增加,差异均有统计学意义(均为P＜0.01);不同浓度PC组间随PC浓度增加线粒体复合物Ⅰ mRNA表达增加,各PC浓度组组间差异有统计学意义(P＜0.01).结论 外源性PC可以增加氧化应激HTMC线粒体复合物I mRNA的表达,有较强的抗氧化作用,并在一定范围内随着浓度的增加其抗氧化作用逐渐增强,PC在青光眼的临床治疗中的作用值得进一步研究.     

miR-181 a靶向沉默信息调节因子相关酶1在过氧化氢诱导的人小梁网细胞氧化应激中的调节作用

目的 探讨miR-181a对过氧化氢(H2O2)诱导的人小梁网细胞(HTMCs)氧化应激的调节作用及其机制.方法 HTMCs随机分为空白组(0μmol·L-1 H2 O2)、200μmol·L-1 H2 O2组、400μmol·L-1 H2 O2组、600μmol·L-1 H2 O2组,分别使用相应浓度H2 O2处理H...     

小梁网的干细胞移植治疗原发性开角型青光眼的研究进展

原发性开角型青光眼(primary open angle glaucoma,POAG)是以持续性眼压增高导致视神经损伤为主要临床表现的一种疾病,其发病机制复杂,尚未明确,现阶段临床治疗相对困难。影响眼内压(intraocular pressure,IOP)高低的重要因素是房水引流是否通畅,而房水引流途径中小梁网(trabecular meshwork,TM)起重要调控作用。TM细胞的形态、数量、结构和功能改变均可使房水外流阻力增大,从而导致IOP升高。研究证实诱导多功能干细胞(induced pluripotent stem cells,iPSCs)、骨髓间充质干细胞(bone mesenchymal stem cells,BMSCs)和脂肪干细胞(adipose-derived stem cells,ADSCs)已被用于TM细胞的分化和再生,为POAG小梁网的干细胞替代治疗提供可靠的细胞来源。近年研究发现,小梁网干细胞(trabecular meshwork stem cells,TMSCs)在分化为TM细胞方面具有绝对优势,为细胞移植治疗青光眼提供新的靶向,这标志着干细胞治疗POAG进入一个新纪元,为青光眼治疗带来新的曙光。本文将对不同种类干细胞的小梁网移植进行综述,为细胞移植治疗POAG提供新思路。     

健康人和青光眼患者小梁网-Schlemm管的形态学特征

房水循环障碍导致的眼压升高是青光眼发生发展的主要危险因素。小梁网-Schlemm管途径引流75%～80%的房水，其结构在不同生理条件下发生持续动态变化从而引起眼压波动。大量研究表明青光眼患者眼压升高与小梁网和Schlemm管形态改变之间关系紧密，但目前缺乏系统性综述。本文就健康人和多种类型青光眼患者中小梁网及Schlemm管的形态学特征进行综述，以期为青光眼发病机制、预防和治疗的进一步探究提供参考。     

外伤性房角后退型青光眼小梁网超微结构的改变

本文报道三例外伤性房角后退型青光眼患者,应用光学显微镜和透射电子显微对其小梁标本进行超微结构的研究。三例标本均可见小梁细胞减少、变性和小梁纤维变性、结构紊乱。我们的研究表明：挫伤后小梁网组织结构的破坏导致房水引液受阻、眼压升高,这是外伤性房角后退型青光眼的主要发病机制。     

小梁网细胞外基质与原发性开角型青光眼的病因研究

小梁网细胞外基质与原发性开角型青光眼的病因研究陈林闻毅颐广州市第二医院眼科（５１０１５０）小梁网是小梁细胞贴附于小梁柱上形成的筛网状结构。房水是通过网孔引流的。房水引流通畅与否直接与网孔大小有关。小梁网细胞外基质（ＥｘｔｒａｃｅｌｕｌａｒＭａｔｒｉ...     

原花青素对氧化应激人眼小梁网细胞凋亡及细胞色素C释放的影响

目的 研究原花青素对H2O2诱导人眼小梁网细胞(human trabecular meshwork cells,HTMC)凋亡及细胞色素C释放的影响.方法 将HTMC进行传代后随机分为5组.未处理组:正常培养的HTMC;对照组:正常培养的HTMC+H2O2(500μmol·L-1处理lh);3个浓度的原花青素组:正常培养的HTMC+H2O2(500 μmol· L-1处理lh)+原花青素(浓度分别为0.02 g·L-1、0.05 g·L-1、0.10g·L-1).使用Annexin V-FITC检测细胞凋亡情况,Western blot检测HTMC胞浆细胞色素C含量.结果 与未处理组相比,对照组及各原花青素组细胞凋亡率均升高,差异均有统计学意义(均为P＜0.01).与对照组相比,各原花青素组细胞凋亡率均降低,差异均有统计学意义(均为P＜0.01);不同浓度原花青素组间随原花青素浓度增加细胞凋亡率下降,各原花青素组间差异均有统计学意义(均为P＜0.01).与未处理组相比,对照组以及0.02 g·L-1和0.05 g· L-1原花青素组细胞色素C的释放均增加,差异均有统计学意义(均为P＜0.01);而0.10 g·L-1原花青素组与未处理组相比,差异无统计学意义(P＞0.05).与对照组相比,各原花青素组细胞色素C释放均减少,差异均有统计学意义(均为P＜0.01).不同浓度原花青素组间随原花青素浓度增加细胞色素C的释放减少,各组间差异均有统计学意义(均为P＜0.01).结论 外源性原花青素可以降低氧化应激HTMC的凋亡率,减少细胞色素C的释放,有较强的抗氧化作用,并在一定浓度范围内随着浓度的增加其抗氧化作用逐渐增强.     

Real-time measurements of nicotinamide adenine dinucleotide in live human trabecular meshwork cells: effects of acute oxidative stress

The trabecular meshwork (TM) region of the eye is exposed to a constant low-level of oxidative insult. The cumulative damage may be the reason behind age-dependent risk for developing primary open angle glaucoma. Chronic and acute effects of hydrogen peroxide (H₂O₂) on TM endothelial cells include changes in viability, protein synthesis, and cellular adhesion. However, little if anything is known about the immediate effect of H₂O₂ on the biochemistry of the TM cells and the initial response to oxidative stress. In this report, we have used two-photon excitation autofluorescence (2PAF) to monitor changes to TM cell nicotinamide adenine dinucleotide (NADPH). 2PAF allows non-destructive, real-time analysis of concentration of intracellular NADPH. Coupled to reduced glutathione, NADPH, is a major component in the anti-oxidant defense of TM cells. Cultured human TM cells were monitored for over 30 min in control and H₂O₂-containing solutions. Peroxide caused both a dose- and time-dependent decrease in NADPH signal. NADPH fluorescence in control and in 4 mM H₂O₂ solutions showed little attenuation of NADPH signal (4% and 9% respectively). TM cell NADPH fluorescence showed a linear decrease with exposure to 20 mM H₂O₂ (−29%) and 100 mM H₂O₂ (37%) after a 30 min exposure. Exposure of TM cells to 500 mM H₂O₂ caused an exponential decrease in NADPH fluorescence to a final attenuation of 46% of starting intensity. Analysis of individual TM cells indicates that cells with higher initial NADPH fluorescence are more refractive to the apparent loss of viability caused by H₂O₂ than weakly fluorescing TM cells. We conclude that 2PAF of intracellular NADPH is a valuable tool for studying TM cell metabolism in response to oxidative insult.     

小梁细胞表达的miRNA研究新进展

ｍｉＲＮＡ是一种长约２２个核苷酸的非编码蛋白质的单链小ＲＮＡ,其对基因的调控主要是在转录后和翻译水平来调节基因表达。目前发现与眼部相关的ｍｉＲＮＡ已达上百种,有不少研究旨在探索ｍｉＲＮＡ在人小梁细胞上的表达及其与靶基因之间的调控机制,为进一步阐述青光眼的发病机制及其诊断、治疗提供更好的理论依据。近年来,有关ｍｉＲＮＡ与眼部组织发育、眼部疾病关系的探讨已成为眼科领域研究热点之一。本文就小梁细胞表达的ｍｉＲＮＡ研究最新进展作一综述。     

Apoptosis in the iris and trabecular meshwork of medically treated and untreated primary open angle glaucoma patients

AIM: To compare the trabecular meshwork (TM) and iris apoptosis of treated and untreated primary open angle glaucoma (POAG) patients.METHODS: Eight treatment-naive, newly diagnosed (group 1) and 11 medicaly treated (group 2) patients with POAG were included in the study. Each patient underwent a limbus-based trabeculectomy. The TM and peripheral iris specimens were dissected out and were snap-frozen in liquid nitrogen and stored at –80℃ until they were assayed. Apoptosis in each group was assesed by TUNEL method.RESULTS:The mean patient age was 60.6±5.8 years (53-68 years) vs 58.9±8.9 years (47-70 years) in group 1 and group 2 (P=0.859). The mean treatment time in group 2 was 22.2±7.3 months (12-34 months). Apoptotic indexes in TM and iris were significantly higher in POAG patients using medication (group 2) compared to treatment-naive POAG patients (group 1) (P=0.004, 0.015; respectively).CONCLUSION: Long term administration of topical antiglaucoma medications causes additional toxic effects on TM.     

Structural changes of the trabecular meshwork in different kinds of glaucoma

The morphology of the trabecular meshwork in three types of open angle glaucoma: primary open angle glaucoma (POAG), corticosteroid-induced glaucoma and pigmentary glaucoma (PG) are described.Ageing is one major risk factor for development of POAG. It is assumed that preexisting age-related changes of the trabecular meshwork (TM) play a role for the development of increased outflow resistance and intraocular pressure (IOP) in various types of glaucoma. These age-related changes in the TM develop concomitant with that of presbyopia. Therefore the functional relationship between ciliary muscle (CM) and TM and the age-related changes in morphology of the outflow system are described first. One main finding in the ageing TM concerns changes of the elastic fiber network and the anterior elastic tendons of the CM. There is an increase in thickness of the sheath of the elastic fibers. Cross-sections through these fibers with their sheath appear as extracellular plaques and were therefore termed “sheath derived plaques” (SD-plaques).Morphologically, the TM changes in POAG resemble that of the ageing TM, but in POAG there is a significant increase in SD-plaques compared to age-matched controls. This increase is due to fine fibrils and other components of the extracellular matrix (ECM) that adhere to the sheaths of the elastic fibers and their connections to the inner wall endothelium. In POAG eyes there is also a marked loss of TM cells, at places leading to fusion and thickening of trabecular lamellae.In steroid-induced glaucoma there is also an increase in fine fibrillar material in the subendothelial region of SC. In contrast to POAG eyes these fibrils do not adhere to the sheath of the elastic fibers but are deposited underneath the inner wall endothelium. The main finding in steroid-induced glaucoma is an accumulation of basement membrane-like material staining for type IV collagen. These accumulations are found throughout all layers of the TM.In pigmentary glaucoma loss of cells was more prominent than in POAG eyes. Presumably, this cell loss occurs after overload of TM cells with pigment granules. Denuded TM lamellae fuse and the TM collapses. In the subendothelial region of these collapsed TM areas an increase in ECM presumably due to underperfusion was observed. At other places SC was occluded and the cribriform region appeared disorganized. In most parts of the circumference of the eye, the TM cells contained pigment granules. Occlusion of TM spaces by pigment granules or cells loaden with pigment was not seen in eyes with PG.