Suppression of human lens epithelial cell proliferation by proteasome inhibition, a potential defense against posterior capsular opacification

PURPOSE: Posterior capsular opacification (PCO) is caused by the proliferation, migration, and epithelial-mesenchymal transition (EMT) of the remaining lens epithelial cells (LECs) after cataract surgery. Studies have shown that proteasome inhibition interferes with EMT and remodeling of the extracellular matrix. This study was conducted to investigate suppression of LEC proliferation by proteasome inhibition and its signaling pathway. METHODS: HLE B-3 cells and human lens epithelium explants from 17- to 20-week fetal lenses were cultured and treated with TGF-beta2 (1 or 10 ng/mL), FGF-2 (20 or 50 ng/mL), HGF (10 ng/mL) and 5 or 10 muM MG132. LEC proliferation was determined using both the WST-1 reagent and proliferating cell nuclear antigen (PCNA) expression. Protein expression was observed by Western blot analysis. Transfection with p21/p27 siRNA was performed to evaluate the mechanism of the antiproliferative effect of proteasome inhibition. RESULTS: TGF-beta2 suppressed proliferation of HLE B-3 cells, whereas FGF-2 and HGF enhanced proliferation. Proliferation suppression by TGF-beta2 was blocked by adding FGF-2 or HGF. Proteasome inhibitor (MG132) treatment strongly inhibited the proliferation of LECs, either alone or in the presence of TGF-beta2, FGF-2, or HGF. These findings were confirmed by observing PCNA expression. Similar results were obtained with primary human LECs. Expression of cell cycle regulatory proteins was determined to evaluate the mechanism of the antiproliferative activity of proteasome inhibition. MG132 caused a significant increase in p21 and p27 protein and decrease in CDK2, but no change in p53, p57, CDK4, or CDK6 protein. The antiproliferative effect of MG132 was significantly reversed in samples transfected with p21 and p27 siRNA, which reduced p21 and p27 protein expression to very low levels that remained below basal control levels, even after treatment with MG132. CONCLUSIONS: Proteasome inhibition decreases the proliferation of LECs in the presence or absence of TGF-beta2, FGF-2, and HGF. This process is mediated in part by an increase in p21 and p27 proteins. These findings suggest that proteasome inhibitors are good candidates for blocking development of PCO.     

早期Nd:YAG激光后囊切开预防青壮年白内障术后后囊混浊

目的：寻找预防青壮年白内障术后后囊混浊的简单方法。

方法：在行白内障超声乳化吸出联合人工晶状体植入后1mo行Nd：YAG激光后囊切开。

结果：观察组21眼经3a随访,3眼出现后囊混浊。对照组20眼,3a时12眼发生后囊混浊,与观察组比较,Z=-3.04,P=0.002,两组差异有统计学意义。

结论：Nd：YAG激光预防性后囊切开,可有效地防止青壮年白内障术后后囊混浊的发生。     

Efficacy and safety of capsular bending ring implantation to prevent posterior capsule opacification: three-year results of a randomized clinical trial

PURPOSE: To determine whether a capsular bending ring (CBR) with a rectangular cross-section and sharp edges moves the barrier to the very equator and avoids contact between the capsulorhexis and optic to prevent posterior capsule opacification (PCO) and anterior capsule fibrosis. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: A 0.7 mm high, open poly(methyl methacrylate) CBR was implanted in 60 eyes (patients) in a prospective randomized intraindividual trial. The impact of additional CBR implantation on PCO and anterior capsule fibrosis was compared to that of intraocular lens (IOL) implantation alone using objective scoring. RESULTS: No CBR-related surgical complications occurred. The objective PCO score and area were statistically significantly reduced in the CBR group. In patients with complete follow-up, the mean PCO score (scale 1 to 10) at 1, 2, and 3 years was 0.8, 1.7, and 2.1, respectively, in the CBR group and 2.6, 3.9, and 4.6, respectively, in the no-CBR group. The number of quadrants affected by PCO was 0.9, 1.5, and 1.8 versus 3.2, 3.8, and 3.8. Barrier failures with the CBR were caused by the inherent slight edge blunting and occasional eyelet gaping. Laser capsulotomies were performed in the no-CBR group only. Capsule stress folds and fibrotic anterior capsule opacification were also greatly reduced. The best corrected visual acuity was better in the CBR group. CONCLUSIONS: Capsular bending ring implantation was an effective and safe adjunct to in-the-bag IOL fixation. With improvements in technology and design securing exquisitely sharp edges and circumferential capsular bending independent of the capsular bag diameter, this concept has the potential to prevent PCO and anterior capsule fibrosis.     

Capsular bending ring to prevent posterior capsule opacification: 2 year follow-up

PURPOSE: To evaluate the preventive effect of a capsular bending ring on anterior and posterior capsule (PCO) opacification in a 2 year clinical study. SETTING: Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. METHODS: This study comprised 60 patients with senile cataract (35 women, 25 men) with a mean age of 69 years. An open poly(methyl methacrylate) capsular bending ring with a truncated edge profile designed to create a sharp bend in the equatorial capsule was implanted in 1 eye of patients with a hydroxyethyl methacrylate intraocular lens (IOL). The contralateral eye, which acted as a control, received an IOL but no ring. Patients were examined 6 months (n = 52), 1 year (n = 48), and 2 years (n = 42) postoperatively. Anterior capsule opacification was determined by slitlamp evaluation. Anterior capsule shrinkage (area within the capsulorhexis) and PCO were evaluated and scored using a computer software package for image analysis. Posterior capsule opacification was also measured by the rate of neodymium:YAG (Nd:YAG) capsulotomies. RESULTS: Anterior capsule opacification and shrinkage were significantly less in eyes with the ring. The mean PCO score was 0.235 +/- 0.215 (SD), 0.287 +/- 0.200, and 0.398 +/- 0.248 with the ring and 0.530 +/- 0.190, 0.670 +/- 0.225, and 1.111 +/- 0.298 without the ring at 6 months, 1 year, and 2 years, respectively (P <.01 at each follow-up). An Nd:YAG laser capsulotomy was performed in 4 eyes with and 17 eyes without the ring after 2 years (P <.01). CONCLUSIONS: The capsular bending ring significantly reduced anterior capsule fibrosis and shrinkage as well as PCO. The ring may be useful in patients who are at high risk of developing eye complications from capsule opacification that require Nd:YAG laser capsulotomy, in those expected to have vitreoretinal surgery and photocoagulation, and in cases of pediatric cataract.     

地塞米松和柔红霉素抑制后囊混浊的体外模拟研究

为评价地塞米松和柔红霉素防治后囊混浊的价值，在体外模拟其在体内的可行性用药方式观察其对牛晶体上皮细胞增殖的抑制作用，结果地塞米松模拟在术后用药７２小时，在房水有效浓度内对晶体上皮细胞无明显抑制作用；提示其防治后囊混浊的作用主要是通过加速血－房水屏障的恢复，减少和控制术后炎症反应而间接实现。柔红霉素模拟加入皮质冲洗液中作用１０分钟，在眼部允许剂量内可呈浓度依赖性抑制晶体上皮细胞增殖，认为按这种方式用药可达到抑制后囊混浊作用。     

依地酸二钠预防后发性白内障的实验研究

目的 探讨应用依地酸二钠(EDTA)清除晶状体上皮细胞,预防后发性白内障的可行性.方法 白内障摘除术中连续环形撕囊后取得人晶状体前囊膜30例,随机分为五组,分别用平衡盐溶液(对照组、A组),5mmol/L、10 mmol/L、15 mmol/L、30 mmol/L的EDTA溶液(B、C、D、E组)进行处理,观察晶状体上皮细胞的清除情况.结果 A组未见明显细胞脱落;B组晶状体上皮细胞仅有少部分脱落;C组和D组晶状体上皮细胞大部分脱落;E组晶状体上皮细胞完全脱落.结论 合适浓度的EDTA可以作为白内障手术中清除晶状体上皮细胞的有效方法,为防治后发性白内障提供理论依据.     

OSCA: a comprehensive open-access system of analysis of posterior capsular opacification

Background  

This paper presents and tests a comprehensive computerised system of analysis of digital images of posterior capsule opacification (PCO). It updates and expands significantly on a previous presentation to include facilities for selecting user defined central areas and for registering and subsequent merging of images for artefact removal. Also, the program is compiled and thus eliminates the need for specialised additional software. The system is referred to in this paper as the open-access systematic capsule assessment (OSCA). The system is designed to be evidence based, objective and openly available, improving on current systems of analysis.     

Use of a polylysine-saporin conjugate to prevent posterior capsule opacification.

PURPOSE: To determine the feasibility of applying a polylysine-saporin (PLS) conjugate to the lens capsule at surgery to prevent lens epithelial cell (LEC) proliferation and posterior capsule opacification (PCO). SETTING: Department of Research & Development, Bausch & Lomb Surgical, and Department of Ophthalmology, Saint Louis University, St. Louis, Missouri, USA. METHODS: Fluorescein-labeled polylysine was applied to the lens capsule of rabbits after phacoemulsification and analyzed histologically to determine the extent of binding to the lens capsule and surrounding tissues. The cytotoxin saporin was conjugated to polylysine using bifunctional cross-linkers. This PLS conjugate was applied to LECs in culture and to the lens capsules of rabbits. These eyes were monitored for PCO. RESULTS: Polylysine primarily bound to the lens capsule membranes, with little or no binding to surrounding tissues. When PLS was added to LECs in culture, it was internalized and destroyed the cells. Of 9 rabbit eyes treated with PLS during surgery, 1 remained free of PCO for the life of the animal (40 weeks), while 6 showed a delay of cortical regrowth approximately 2 to 3 times that of control eyes. CONCLUSIONS: Polylysine bound selectively to the lens capsule membrane. The PLS conjugation resulted in a toxic agent that targeted the lens capsule and destroyed proliferating LECs. The application of a PLS conjugate during surgery may prevent PCO.     

糖尿病对后发性白内障的影响及可能机制的初步研究

目的　探讨２型糖尿病对后发性白内障的影响及其可能的分子机制。方法　收集１０８例（１０８眼）白内障患者房水并行ＥＬＩＳＡ检测房水中ＩＬ-６含量,其中对照组（年龄相关性白内障患者）５０例（５０眼）,试验组（２型糖尿病白内障患者）５８例（５８ 眼）,比较两组最佳矫正视力、眼压、后发性白内障（ｐｏｓｔｅｒｉｏｒｃａｐｓｕｌｅｏｐａｃｉｆｉｃａｔｉｏｎ,ＰＣＯ）发生率、ＰＣＯ严重程度、房水中ＩＬ-６含量等。结果　白内障超声乳化联合人工晶状体植入术均提高了两组患者术后最佳矫正视力,且对照组较试验组最佳矫正视力提高明显（Ｐ＝０．００２）。对照组术前、术后眼压分别为（１３．９３±３．２５）ｍｍＨｇ（１ｋＰａ＝７．５ｍｍＨｇ）、（１４．６０±４．３５）ｍｍＨｇ,差异无统计学意义（Ｐ＞００５）;试验组术前、术后眼压分别为（１４．１８±３．５６）ｍｍＨｇ、（１５．１２±４．６６）ｍｍＨｇ,差异无统计学意义（Ｐ＞ ００５）。对照组ＰＣＯ发生率２６．００％,试验组ＰＣＯ发生率４１．３８％,两组间ＰＣＯ发生率差异无统计学意义（Ｐ＝０．０９５）。试验组房水中ＩＬ-６含量与后发性白内障呈正相关（ｒ＝０７３１,Ｐ＝０００１）,且试验组房水中ＩＬ-６含量较对照组明显升高（Ｐ＝００１２）。结论　房水中ＩＬ-６含量可能促进了糖尿病患者ＰＣＯ的发生发展,其具体机制尚需进一步研究。     

Modification of the surface properties of a lens material to influence posterior capsular opacification

PURPOSE: To study the effect of surface properties of materials on cellular behaviour and the formation of posterior capsular opacification (PCO). METHODS: Polymethylmethacrylate, silicone and a hydrophobic acrylic were plasma treated and used in tissue culture. The changes in surface properties were quantified by dynamic contact angle measurements. Bovine lens epithelial cells (BLECs) were seeded onto these materials and cultured for 1 month. Serial photographs were taken. The cells were then fixed and stained to facilitate counting. RESULTS: Plasma treatment significantly increased the hydrophilicity of surfaces. BLECs grew on all surfaces but significantly more cells adhered to the treated than the untreated surfaces. On the untreated surfaces the BLECs had a fibroblastic morphology whereas on the treated surfaces the cells maintained their epithelial morphology. CONCLUSIONS: Posterior capsular opacification is a form of wound healing and the behaviour of lens epithelial cells is central to its progression. Emphasis has been on the elimination of residual lens epithelial cells to combat PCO. This study demonstrated that the phenotype of BLECs was influenced by the surface properties of the intraocular lens materials. Gas plasma treatment of the materials increased their hydrophilicity and allowed the adhered BLECs to maintain their normal epithelial morphology. We believe that controlled growth of lens epithelial cells may reduce the incidence of PCO.     

Pathogenesis of posterior capsular opacification. Part II: Histopathological and in vitro culture findings

The most interesting sources of information about the pathogenesis of posterior capsular opacification seem to be histopathological studies and in vitro tissue cultures. Since our surgical technique is extracapsular cataract extraction, the explants we used for tissue culture consisted of the anterior capsule epithelial sheet without the equatorial germinative zone. We successfully overcame several problems by using the autologous plasma clot culture method. This medium, considered the optimal one for this type of culture, allowed us to study the heterogeneous behavior of the epithelial cells in culture. Using the plasma clot culture method, we were able to demonstrate in vitro fibroblastic transformation of the epithelial cells. Histopathological findings of particular cases of posterior capsule opacification and immunohistochemistry of the human lens are also reported.     

Efficacy of different intraocular lens materials and optic edge designs in preventing posterior capsular opacification: a meta-analysis

PURPOSE: To evaluate the efficacy of different intraocular lens (IOL) materials and optic edge designs in preventing posterior capsular opacification (PCO). DESIGN: Systematic review and meta-analysis. METHODS: Pertinent studies were selected through an electronic search of the Cochrane Library, MEDLINE, and Embase. The randomized controlled trials meeting the predefined criteria were reviewed systematically by meta-analysis. The treatment effects were measured as risk difference, and the pooled estimates were computed according to a random effect model. RESULTS: In total, 23 randomized controlled trials were included in the present meta-analysis. The pooled risk differences of Nd:YAG laser capsulotomy rates were -24% (95% confidence interval [CI], -29% to -20%) comparing acrylic with polymethylmethacrylate (PMMA) lenses; -9% (95% CI, -17% to -1%) comparing silicone with PMMA lenses; 14% (95% CI, -8% to 36%) comparing hydrogel with PMMA lenses; 4% (95% CI, -2% to 10%) comparing silicone with acrylic lenses; 19% (95% CI, 8% to 30%) comparing hydrogel with acrylic lenses; and 28% (95% CI, 10% to 46%) comparing hydrogel with silicone lenses. The pooled risk differences of PCO rates were -39% (95% CI, -47% to -31%) comparing acrylic with PMMA lenses; -14% (95% CI, -29% to 0%) comparing silicone with acrylic lenses; 56% (95% CI, 36% to 75%) comparing hydrogel with acrylic lenses; and 48% (95% CI, 31% to 64%) comparing hydrogel with silicone lenses. When comparing sharp with rounded-edge designs, pooled risk differences of capsulotomy rates were -47% (95% CI, -77% to -17%) in PMMA lenses, -22% (95% CI, -47% to 2%) in acrylic lenses, and -9% (95% CI, -17% to 0%) in silicone lenses; pooled risk differences of PCO rates were -28% (95% CI, -50% to -7%) in acrylic lenses and -37% (95% CI, -46% to -27%) in silicone lenses. CONCLUSIONS: The rates of PCO and Nd:YAG laser capsulotomy may be influenced by different IOL biomaterials and optic edge designs. The lenses made by acrylic and silicone and those with sharp optic edges are superior in lowering the rates of PCO and laser capsulotomy.     

Double-masked prospective ocular safety study of a lens epithelial cell antibody to prevent posterior capsule opacification

PURPOSE: To evaluate the intraocular safety of an immunoconjugate (MDX-RA) developed to prevent posterior capsule opacification (PCO) in human eyes. SETTING: St. Thomas's Hospital Eye Department, London, United Kingdom. METHODS: Twenty-six patients had phacoemulsification and implantation of an intraocular lens (IOL). All were randomly allocated at the end of surgery to receive a 0.1 mL placebo or 0.1 mL of the immunotoxin MDX-RA intracamerally. Two doses of the drug were tested: 8 patients with a low dose (50 units), 9 patients with a high dose (100 units), and 9 with placebo. Follow-up at days 1, 14, 30, 60, 90, and 180 consisted of visual acuity measured by the Early Treatment of Diabetic Retinopathy Study test, contrast sensitivity, aqueous flare, specular microscopy of the IOL's anterior surface, and corneal endothelial counts. The percentage area of PCO was measured from retroillumination images of the posterior capsule. RESULTS: There was no decrease in corneal endothelial cell count in toxin-treated patients. Early postoperative flare, anterior chamber cell count, and corneal pachymetry were higher in toxin-treated patients. The median percentage area of PCO at 1 year was 32.0 in the placebo group, 3.8 in the low-dose group, and 7.4 in the high-dose group (P = .06). CONCLUSION: This prospective, randomized, placebo-controlled trial confirmed that MDX-RA is safe for intraocular use and is of potential value for further clinical trials of the prevention of PCO.     

The effect of capsulorhexis size on posterior capsular opacification: one-year results of a randomized prospective trial.

PURPOSE: Posterior capsular opacification is the most common surgically related cause of reduced vision after cataract surgery. We studied the effect of capsulorhexis size on the pattern and severity of posterior capsular opacification. METHODS: In this prospective study 75 patients underwent standardized phacoemulsification with capsulorhexis and in-the-bag placement of a 5.5-mm polymethylmethacrylate intraocular lens implant. The patients were randomly assigned to receive either a small capsulorhexis of 4.5 to 5 mm to lie completely on the intraocular lens optic or a large capsulorhexis of 6 to 7 mm to lie completely off the lens optic. Patients were examined at days 1, 14, 30, 90, and 180 and at year 1 with logMAR visual acuity assessment, Pelli-Robson contrast sensitivity testing, anterior chamber flare and cell measurement, and high-resolution digital retroillumination imaging of the posterior capsule. The pattern of posterior capsular opacification was determined, and the percentage area of posterior capsular opacification was calculated for each image with dedicated image analysis software. RESULTS: Large capsulorhexes were associated with significantly more wrinkling of the posterior capsule and worse posterior capsular opacification than small capsulorhexes. At 1 year the average percentage area of posterior capsular opacification was 32.7% for small capsulorhexes (95% confidence interval, 19.8 to 45.6) and 66.2% for large capsulorhexes (95% confidence interval, 57.7 to 74.6) (P = .0001). The patients with large capsulorhexes had significantly poorer visual acuities and a trend toward worse contrast sensitivities. CONCLUSION: This study demonstrated significantly greater wrinkling and opacification of the posterior capsule and worse visual acuity with large capsulorhexes than with small capsulorhexes. In cataract surgery with a polymethylmethacrylate intraocular lens, a small capsulorhexis with the edge completely on the surface of the implant is preferable to a large capsulorhexis in reducing posterior capsular opacification.     

組織纖溶酶原激活劑、肝素對晶體后囊膜混濁抑制作用的實驗對比研究

目的觀察tPA(組織纖溶酶原激活劑)、肝素對兔眼PC-IOL(后房型人工晶體)植入術后晶體后囊膜混濁的抑制作用.方法 48只新西蘭大白兔分爲三組(對照組、tPA組和肝素組),常規晶體囊外摘除及PC-IOL植入,術中分别應用0.2ml(tPA25ug)和肝素100U/ml灌注液,于術后1、3天和1、3月分别取后囊膜行纖維蛋白和后囊膜增厚程度檢測.結果 tPA、肝素對后囊膜上的纖維蛋白反應在術后1、3天均有抑制作用,二組的后囊增厚程度在術后1月時均較對照組爲輕.結論 tPA、肝素對術后早期后囊膜混濁有一定的抑制作用.     

Inhibitory effects of salmosin,a disintegrin,on posterior capsular opacification in vitro and in vivo

The proliferation, migration and transdifferentiation of the remaining lens epithelial cells (LECs) after cataract surgery are a major cause of posterior capsular opacification (PCO). It has previously been reported that salmosin, a novel disintegrin, significantly inhibits solid tumor growth in mice by perturbation of tumor-specific angiogenesis via blocking alpha v beta 3 integrin expressed on vascular endothelial cells. In this study, the inhibitory function of salmosin in PCO was investigated and was found that salmosin inhibits the attachment of bovine LECs and rabbit lens cells (N/N1003A) to extracellular matrix-coated plates. The anti-adhesive activity of salmosin was approximately 1000 times higher than that of synthetic Arg-Gly-Asp peptide. In addition, the cell proliferation and migration of bovine LECs and N/N1003A were strongly inhibited by salmosin, whereas the proliferation of corneal endothelial cells was less affected. LEC migration and proliferation were also decreased by salmosin treatment in rabbit eyes without any toxic effect in the cornea, iris and retina. In this study, salmosin was shown to specifically inhibit LEC migration and proliferation in an animal model. Therefore, the authors suggest that further investigation may show salmosin to be a good candidate for inhibiting PCO development.     

白内障术后后囊浑浊的防治和抗人晶状体上皮细胞单克隆抗体的制备

目的制备可特异性识别人晶状体上皮细胞的单克隆抗体，筛选特异性强亲和力高的克隆。方法以原代培养人晶状体上皮细胞作为免疫原，使用杂交瘤技术制备抗人晶状体上皮细胞单克隆抗体（monoclonal antibody，McAb）。小鼠腹腔接种杂交瘤细胞制备腹水，用免疫荧光、免疫组化法对其特性进行鉴定。结果获得了1株稳定分泌抗人晶状体上皮细胞McAb的杂交瘤细胞系，其亚类为IgM。免疫荧光和免疫组化检测结果显示，此McAb与人晶状体上皮细胞膜上的抗原反应，与人眼其他组织呈阴性反应。结论所获抗体可特异性识别人晶状体上皮细胞，可进一步制备免疫导向药物，用于白内障术后后囊浑浊的治疗。     

Osteopontin: a component of matrix in capsular opacification and subcapsular cataract

PURPOSE: To examine whether tissues of human capsular opacification and subcapsular cataract contain osteopontin, an adhesive matrix protein, and whether mouse lens epithelium expresses osteopontin after injury. METHODS: An immunohistochemical examination was conducted to determine whether matrices in human postoperative capsular specimens and anterior subcapsular cataract contain osteopontin. The spatial and temporal protein expression patterns of osteopontin were then determined in epithelium of a healing mouse lens after a capsular incision. RESULTS: Human lens epithelial cells in the specimens extracted at the time of vitrectomy 10 days after cataract surgery and also after longer healing intervals were labeled with an anti-osteopontin antibody, whereas uninjured lens epithelium was not. In the later healing phase, matrix of capsular opacification was positive for osteopontin. Lens cells amid anterior subcapsular cataract tissue were also positive. Osteopontin was detected in the cell surface and membrane and the cytoplasm of lens cells, as well as in the matrix. Unlike normal uninjured specimens, anterior lens capsule of some of the healing postoperative specimens and anterior subcapsular cataract specimens also faintly or weakly stained for osteopontin. Mouse lens epithelium started to express osteopontin protein at 8 hours after injury, before the cells changed their shape from epithelial cell type to fibroblast type. Expression of osteopontin lasted during the healing interval, even after the cells transformed into fibroblast-like cells. CONCLUSIONS: Extracellular matrix in human postoperative capsular opacification and anterior subcapsular cataract contains osteopontin. Epithelial cells of a mouse lens also ectopically express osteopontin in response to capsular injury.