Inhibition of lens epithelial cell adhesion by the calcium antagonist Mibefradil correlates with impaired integrin distribution and organization of the cytoskeleton

BACKGROUND: Posterior capsule opacification is the most common complication of primary cataract surgery and is caused by migration and proliferation of residual lens epithelial cells onto the posterior capsule. Interfering with the mechanisms involved in cell adhesion is a suitable approach to prevent posterior capsule opacification. METHODS: Mibefradil, a T-type calcium-channel blocker, was used to examine the influence on adhesion-mediating mechanisms in human lens epithelial cells derived from cataract surgery. Adhesion was evaluated by light microscopy on the anterior capsules. Expression of integrin receptors was studied by flow cytometry. The influence on the distribution of integrin receptors on the cell surface and the organization of the cytoskeleton was examined by immunofluorescence using a confocal microscope. RESULTS: The calcium-channel blocker Mibefradil inhibited cell adhesion on the anterior capsule wall at concentrations between 10 and 100 pNM. The cells expressed the integrin subunits beta1 and alpha3. Mibefradil distinctly impaired the distribution of these integrins on the cell surface in culture. The cells express the cytoskeletal components actin, vimentin and, very weakly, cytokeratin. The structural organization of the actin filaments and vimentin was strongly disrupted with pronounced fragmentation of the actin filaments in the presence of the calcium-channel blocker. CONCLUSION: The results suggest that the inhibition of cell adhesion by the calcium-channel blocker Mibefradil involves the impairment of integrin-mediated mechanisms. The use of this calcium antagonist appears to be a suitable therapeutic approach to prevent posterior capsule opacification.     

整合素在晶状体上皮细胞中的表达及其作用研究进展

整合素是介导细胞与细胞间及细胞与细胞外基质相互作用的重要黏附分子，其可参与晶状体上皮细胞的黏附和移行。本文综述了整合素在晶状体上皮细胞中的表达及其作用，以其对晶状体的发育、白内障及后发障的形成有进一步的了解。     

人工晶状体植入术后房水细胞因子的研究进展

白内障摘除联合人工晶状体植入术作为白内障最主要的治疗手段,人工晶状体的生物相容性一直是研究的热点。从宏观层面,人工晶状体的生物相容性主要反应在人工晶状体植入术后的并发症,如：眼内炎、角膜内皮水肿、虹膜后粘连、葡萄膜炎、后发性白内障等;人工晶状体的生物相容性微观主要表现在房水中的一些细胞反应,如：巨噬细胞、单核细胞、成纤维细胞及人晶状体上皮细胞等在人工晶状体表面的黏附、增殖,且术后并发症是由于房水中细胞因子连续作用于房水内细胞产生的,另一角度讲,房水中细胞因子是桥梁,它一定程度能反应人工晶状体的情况,能更全面的评价人工晶状体的生物相容性,有利于探究白内障术后并发症的发生的机制,提高人工晶状体的生物相容性。     

晶状体上皮细胞转分化对老年性白内障形成的影响研究

目的 :为研究晶状体上皮细胞转分化对老年性白内障形成的影响。方法 :对 14例老年性白内障晶状体前囊上皮细胞进行角质蛋白 -8、波形纤维蛋白和纤维粘连蛋白表达的免疫组化研究。结果 :皮质性白内障晶状体上皮的波形纤维蛋白表达明显强于核性白内障 (P <0 0 5 ) ;角质蛋白 -8在皮质性白内障晶状体上皮的表达比核性白内障弱 ((P <0 0 1) ;纤维粘连蛋白在皮质性白内障晶状体上皮的表达明显强于核性白内障 ,而在正常晶状体上皮不表达。结论 :晶状体上皮细胞具有转分化为成纤维样细胞的双向化潜能。晶状体上皮获得转分化能力后而失去原来的细胞学特性。在老年皮质性白内障中 ,晶状体上皮细胞转分化成为成纤维样细胞 ,伴随波形纤维蛋白的过度表达和角质蛋白表达下降。同时合成包括纤维粘连蛋白在内的细胞外基质增多 ,而纤维粘连蛋白能促进晶状体上皮的增殖、迁移及粘附 ,因而晶状体上皮细胞转分化对老年性白内障形成及后囊混浊的形成发挥重要作用。     

Survey of intraocular lens material and design.

Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.     

Lens epithelial cells express CD95 and CD95 ligand treatment induces cell death and DNA fragmentation in vitro

PURPOSE: Despite advances in intraocular lens design and material, posterior capsule opacification remains one of the major problems in modern cataract surgery. Therefore, the use of antiproliferative agents has been advocated. CD95 ligand (CD95L, Fas, Apo-1) is a death ligand that triggers apoptosis in susceptible target cells. Apoptosis allows for the safe disposal of cells without damaging the surrounding tissue. The goal of this study was to characterize and evaluate CD95L-induced cell death in cultured lens epithelial cells (LEC). METHODS: Expression of CD95 in untreated porcine LEC was investigated by flow cytometry. Cell death after CD95L or CD95 agonistic antibody treatment was assessed by crystal violet assay and DNA fragmentation was measured by comet assay. RESULTS: The presence of CD95 was observed in LEC. CD95L treatment resulted in a time--and concentration-dependent killing of LEC, which was synergistically enhanced by the addition of cyclohexamide. CD95L treatment induced DNA fragmentation. CONCLUSIONS: The present study confirms the use of apoptosis-inducing CD95L in the inhibition of LEC proliferation. Further studies are needed before clinical application of CD95L to inhibit posterior capsule opacification will be feasible.     

MMP inhibition prevents human lens epithelial cell migration and contraction of the lens capsule

PURPOSE: The development of posterior capsule contraction following cataract surgery is caused by the activity of residual lens epithelial cells. Matrix metalloproteinases (MMPs) are a group of proteolytic enzymes, which are essential for cell migration and cell mediated contraction following wound healing. The authors investigated whether inhibiting MMP activity can reduce lens epithelial cell migration and as a result, lead to a reduction in cell mediated capsule contraction. METHODS: Human donor lens capsules were cultured and treated with a broad spectrum MMP inhibitor, Ilomastat (GM6001). MMP-2 and MMP-9 production were determined by ELISA. Cell migration onto the posterior capsule and capsule contraction were digitally measured. RESULTS: MMP inhibition significantly reduced lens epithelial cell migration onto the posterior capsule (p<0.05), and a reduction in capsule contraction was observed (p<0.05). CONCLUSIONS: Ilomastat significantly reduced lens epithelial cell migration onto the posterior capsule surface and inhibited capsule contraction. MMP inhibition may have a role in the therapeutic treatment of posterior capsule opacification.     

血小板源性生长因子与后发性白内障的研究进展

后发性白内障(posterior capsule opacification,PCO)是白内障手术后较为常见的并发症。近年来随着分子生物学及细胞生物学技术的发展,发现生长因子类物质如血小板源性生长因子(platelet-derived growth factor,PDGF)与晶状体上皮细胞的增殖、迁移、纤维分化有密切的关系,对PDGF进行适当的调控可能对于防治PCO有重要意义。我们围绕PDGF对晶状体上皮细胞的作用、PDGF及其受体对PCO形成的影响作简要综述。     

靶向治疗后囊混浊的研究进展

后囊混浊是白内障手术的常见并发症。残留晶状体上皮细胞在后囊的增殖、移行、纤维化生是后囊混浊形成的重要因素。用于防治后囊混浊的许多约物如道诺霉素、丝裂霉素等，因眼内的毒副作用而受到限制。靶向治疗的特异性、针对性为解决这一问题带来了希塑。综述了靶向治疗后囊混浊的研究现状及对未来的研究展望。     

整合素连接激酶在白内障发病过程中的作用

整合素是一种在哺乳动物体内广泛表达的细胞表面受体,整合素连接激酶(ILK)是整合素信号通路的关键激酶,其与整合素结合进行细胞与细胞外基质(ECM),甚至细胞与细胞之间的信号传导.目前的研究发现,ILK及其整合素信号通路的活化可以激活磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(PI3K/AKT)和转化生长因子β/Smad蛋白(TGF-β/Smad)介导的细胞增生、黏附和迁移,引起晶状体上皮细胞异常增生和纤维化,还能激活糖原合成酶激酶3β/β-链蛋白(GSK3β/β-catenin)等信号通路,介导水通道蛋白(AQPs)调节水转运过程,最终导致晶状体内囊泡运输受限,渗透压改变,从而引起白内障.白内障是世界主要的致盲眼病之一,其主要由于老化、遗传、代谢异常、外伤、辐射、中毒和局部营养不良等引起的晶状体囊膜损坏,使其渗透性增加,丧失屏障作用,或导致晶状体代谢紊乱,使晶状体蛋白发生变性,形成混浊,但其发病机制尚未完全阐明.ILK可以通过多种信号通路介导人晶状体上皮细胞的移行、黏附、增生和凋亡,因此深入研究ILK在白内障发病中的作用对白内障的预防和治疗有重要意义.本文就近年来ILK在白内障发病中的作用进行综述.     

Migration of lens epithelial cells through haptic root of single-piece acrylic-foldable intraocular lens

PURPOSE: To report a case of posterior capsule opacification after cataract surgery due to lens epithelial cell migration through the haptic root of a single-piece acrylic-foldable intraocular lens. DESIGN: Interventional case report. METHODS: A 60-year-old man with senile cataract underwent phacoemulsification and implantation of single-piece acrylic intraocular lens having thick and wide haptic loops. RESULTS: There were no operative or short-term postoperative complications, and patient's visual acuity was 20/20 on the day following surgery. At 19 months postoperatively, we observed posterior capsule opacity extending from the base of the intraocular lens loops. CONCLUSION: Broad and thick haptic root can be a path through which lens epithelial cells migrate toward the center of the posterior capsule, forming posterior capsule opacification.     

Activation of SRC kinases signals induction of posterior capsule opacification

PURPOSE: Posterior capsule opacification (PCO) is a complication of cataract surgery resulting from the proliferation, migration, and epithelial-to-mesenchymal transition (EMT) of lens epithelial cells that remain associated with the lens capsule. These changes cause a loss of vision. The authors developed a chick embryo lens capsular bag model to study mechanisms involved in the onset of PCO. Because Src family kinases (SFKs) signal cell proliferation, migration, and EMT, the authors examined whether the inhibition of SFKs can prevent PCO. METHODS: After mock cataract surgery, chick lens capsular bags were pinned to a culture dish and grown in the presence or absence of the SFK inhibitor PP1. Cell movement was followed by photomicroscopy. Progression of proliferation and EMT in the PCO cultures was determined by Western blot analysis and immunofluorescence staining. RESULTS: As occurs in PCO, lens cells in this model proliferated, migrated across the posterior capsule, and expressed EMT markers, alpha-smooth muscle actin (alpha-SMA), and fibronectin (FN). Lens cells treated with PP1 maintained an epithelial phenotype, accumulated cadherin junctions, and did not migrate to the posterior capsule, increase proliferation, or express EMT markers. Therefore, exposure to PP1 prevented PCO. Short-term inhibition of SFKs was sufficient to prevent EMT, but longer inhibition was necessary to prevent lens cell migration. CONCLUSIONS: Progression of PCO involved early activation of SFKs. Lens cell migration preceded EMT, and each of these two events required activation of an SFK signaling pathway. Suppression of SFK activation blocked PCO, suggesting SFKs as a therapeutic target for the prevention of PCO.     

EGF-induced cell migration is mediated by ERK and PI3K/AKT pathways in cultured human lens epithelial cells.

Cataract is considered as the most common cause of blindness, which is curable only by surgery. Postsurgery, however, many patients gradually develop the complication of posterior capsule opacification (PCO) or secondary cataract, arising from stimulated cell proliferation and cell migration within the lens capsule. The migration of human lens epithelial cells (HLECs) plays crucial roles in the remodeling of lens capsule and cataract formation, but less is known about the cell-signaling mechanism of migration. We observed that epithelial growth factor (EGF) induced cell migration in cultured human lens epithelial cells through the ERK and PI3K/AKT pathways. EGF induced cell migration in a dose-dependent manner; EGF-induced EGFR phosphorylation and downstream activation of c-Jun N-terminal protein kinase (JNK), p38 MAP kinase (p38), extracellular signal-regulated kinase (ERK1/2) and AKT, were inhibited by PD153035 (EGFR inhibitor), JNKi (JNK inhibitor), SB203580 (p38 inhibitor), U0126 (MEK/ERK inhibitor), and LY294002 (PI3K/AKT inhibitor), respectively. Furthermore, we found that EGF induced activity of matrix metalloproteinase-2 (MMP-2) in cultured HLECs. EGF-induced MMP-2 activity was significantly inhibited by treatment of PD153035, U0126, and LY294002, but not SB203580 and JNK inhibitor, suggesting that ERK and the phosphatidylinositol-3-kinase (PI3K)/AKT pathways selectively mediate EGF-stimulated MMP-2 activity and cell migration in cultured HLECs in vitro. Taken together, our results suggest that the cell-signaling pathways involved in EGF-stimulated cell migration may constitute potential therapeutic targets in the treatment of PCO.     

Posterior capsule opacification: a specular microscopic study

Posterior capsule opacification following extracapsular cataract extraction is a manifestation of migration of lens epithelial cells onto the posterior capsule. Collagen production by these epithelial cells results in white "fibrotic" opacities. These cells have myoblastic features and their contraction produces wrinkling of the posterior capsule resulting in visual distortion. A high magnification, in vivo specular microscopic study of human posterior capsules following extracapsular cataract extraction is described. In vivo findings correlate with histopathologic observations made on opacified posterior capsules. Lens epithelial cells migrate onto the posterior capsule and produce basement membrane and collagen. Collagen production is associated with a spindle-shaped appearance of the hyperplastic cells. This technique is useful for clinical research on posterior capsule opacification, including the evaluation of interventions designed to treat or prevent this complication.     

Posterior Capsule Opacification in Pseudophakic Eyes

Posterior capsule opacification following extracapsular cataract extraction is a manifestation of proliferation of anterior lens epithelium onto the posterior capsule. In addition to Elschnig pearl formation, vision is decreased in two ways. Multiple layers of proliferated epithelium produce a frank opacity. Also, the lens cells show myofibroblastic differentiation and their contraction produces numerous tiny wrinkles in the posterior capsule resulting in visual distortion. Because the cells that proliferate are anterior lens epithelial cells and because proliferation begins at the site of apposition of anterior capsular flap and the posterior capsule, a wide anterior capsulectomy should help reduce the risk of and delay the onset of visual loss from this complication of extracapsular surgery. Polishing the posterior capsule at the time of surgery will not help in this regard unless there is a complicated cataract with pre-existing posterior migration of lens epithelium. The presence of a potential cleavage plane between the proliferating epithelium and the posterior capsule provides a therapeutic alternative to surgical or laser discission.     

后发性白内障的发病机制和药物防治的研究现状及前景

后发性白内障是现代白内障术后最常见的并发症。术后晶状体囊残留的晶状体上皮细胞的增殖、迁移、纤维化生是形成后发性白内障的主要原因。目前防治后发障的研究主要集中在药物除去或破坏残留晶状体上皮细胞。实验研究许多细胞毒药以及抑制晶状体上皮细胞生长和纤维化药物可以预防后发障,但目前临床上还没安全、有效的防治白内障方法。     

In vivo human lens epithelial cell proliferation on the anterior surface of PMMA intraocular lenses.

AIMS: To study in vivo human lens epithelial cell proliferation on the anterior surface of PMMA implants and its interaction with postoperative blood-aqueous barrier breakdown in eyes undergoing cataract surgery. METHODS: A prospective study was carried out on three consecutive patient cohorts undergoing cataract surgery with intraocular lens implantation using three different surgical techniques which produce different anatomical relations between the implant and lens capsule. Specular microscopy of the anterior implant surface was used to document the natural history, topography, and density of lens epithelial cells and the laser flare and cell meter were used to measure postoperative blood-aqueous barrier breakdown. RESULTS: All groups showed lens epithelial cell proliferation onto the anterior surface of PMMA implants. This was initiated by and restricted to the region of anterior capsule-implant contact and decreased with the onset of anterior capsular opacification. Significant correlation was found in all groups between lens epithelial cell proliferation and postoperative blood-aqueous barrier breakdown. CONCLUSIONS: Human lens epithelial cell behaviour on PMMA surfaces in vivo differs from that seen in culture studies. Humoral factors in the aqueous, biomaterial properties of the implant, and its anatomical relations with the anterior and posterior lens capsule influence lens epithelial cell behaviour in vivo.     

Differential responses of human lens epithelial cells to intraocular lenses in vitro: hydrophobic acrylic versus PMMA or silicone discs

Background The purpose of this study was to determine the influence of different materials of intraocular lenses (IOLs) on human lens epithelial cell behavior, including adhesion, migration, proliferation, apoptosis, and epithelial-mesenchymal transdifferentiation (EMT) in vitro. Methods Human lens epithelial cells (SRA 01/04) were grown on hydrophobic acrylic (Acrysof), polymethylmethacrylate (PMMA), and silicone IOLs. Cellular adhesion, migration, proliferation, and apoptotic assays were performed to assess cell behavior. The expression of EMT markers (fibronectin and type I collagen) produced by cells on IOLs was determined by immunoblotting and immunocytochemistry. Results Human lens epithelial cells exhibited preferred adhesion and reduced apoptosis when cultured on acrylic IOLs, in comparison to PMMA and silicone IOLs. Cells grown on acrylic lenses formed a confluent epithelial monolayer. Migration of lens epithelial cells under the acrylic lens was substantially blocked in an in vitro assay. In contrast, cells grown on PMMA and silicone lenses displayed a spindle-shaped, myofibroblast-like morphology, increased apoptosis, reduced adhesion, and enhanced production of EMT proteins such as fibronectin and type I collagen. The migration of lens epithelial cells under PMMA and silicone IOLs was substantial in the in vitro assay. Conclusion This report demonstrates that hydrophobic acrylic lenses are more capsular biocompatible than PMMA and silicone lenses. The in vitro assays are reliable measurements for evaluating the responses of human lens epithelial cells to different IOL materials, and could advance our understanding of the preferential capsular opacification conferred by different IOL materials.     

P38在体外培养鸡胚胎晶状体半乳糖性白内障形成中的作用

目的:探讨P38参与的晶状体上皮细胞凋亡的调节在体外培养的鸡胚胎晶状体半乳糖性白内障中的作用。方法:用30mmol/L半乳糖诱导体外培养的鸡胚胎晶状体建立半乳糖性白内障模型,在培养10d里,通过每日观察、照相、计算晶状体的混浊面积,观察MAPK-P38抑制剂SB203580对半乳糖引起的晶状体混浊程度的影响,并用TUNEL原位凋亡细胞染色方法,观察晶状体冰冻组织切片上细胞凋亡情况。结果:半乳糖30mmol/L能诱导体外培养的鸡胚胎晶状体产生周边皮质性混浊,随着半乳糖暴露时间的延长,晶状体的混浊面积增加,P38抑制剂SB203580能有效减轻半乳糖性晶状体的混浊。TUNEL检测显示,在培养2,5,10d的半乳糖性白内障晶状体切片上,凋亡细胞的百分数分别为1.7%,4.5%和12%,而SB203580处理的晶状体,凋亡细胞数明显减少,在相应点分别是0.7%,1.5%和1.4%。结论:P38可能通过参与晶状体上皮细胞凋亡调控在半乳糖性白内障的形成中起作用。抑制P38激活能阻止晶状体细胞凋亡,减轻白内障形成。     

整合素与去整合素在后发性白内障方面的研究现状

晶状体摘除术后晶状体上皮细胞的增殖、黏附和迁移是后发性白内障的主要原因,整合素是一类介导C-C间以及C-ECM间的相互作用的黏附分子,在晶状体上皮细胞的增殖、黏附和迁移过程中发挥重要的作用,去整合素是一种小分子多肽,它可以特异性的被整合素识别并黏附,从而抑制整合素的生物学作用,本文就整合素的功能,整合素在晶状体上皮细胞上的分布及功能,晶状体上皮细胞与后发性白内障之间的关系以及去整合素在后发性白内障防治方面的研究进展做一综述。