Detection of integrins in human cataract lens epithelial cells and two mammalian lens epithelial cell lines

AIM: To compare the incidence of various integrin subunits in human cataract anterior lens epithelial cells (A-LEC) and in two mammalian LEC lines. METHODS: Circular sections of anterior capsules with attached LEC were obtained during cataract surgery. Integrin subunits were immunolocalised in these anterior LEC and in a human and rabbit LEC line, using four monoclonal antibodies specific for subunits alpha2, alpha3, and alpha5, and beta subunit 2. RESULTS: All of these subunits were found in at least a proportion A-LEC samples as follows: alpha2 71%, alpha3 92%, alpha5 62%, and beta2 24%. The human LEC line was immunoreactive for alpha2 and alpha3 only. The rabbit lens epithelial cell line was immunoreactive for alpha5 but there was no staining for alpha2, alpha3, or beta2. CONCLUSION: The A-LEC and mammalian LEC lines showed a similarity in their pattern of integrin expression. As these integrins are receptors for extracellular matrix (ECM) components, they are likely to be associated with the attachment and migration of LECs that precedes capsular opacification. Therefore these cell lines may be useful in the elucidation of mechanisms involved the pathogenesis of capsule opacification.     

Degeneration and transdifferentiation of human lens epithelial cells in nuclear and anterior polar cataracts.

PURPOSE: To study the possible mechanisms of cataractogenesis by evaluating the characteristics of cataractous lens epithelial cells (LECs) in different types of human cataract. SETTING: Kangnam St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea. METHODS: Lens epithelial cells attached to the anterior capsules in eyes with nuclear or anterior subcapsular were analyzed for morphological characteristics by electron microscopy and for cellular characteristics by immunohistochemistry. RESULTS: Human LECs beneath the anterior capsule were degenerated in nuclear cataracts and were transdifferentiated in anterior polar cataracts. In senile nuclear cataractous lenses, LECs beneath the anterior capsule showed degenerative changes in morphology. In nuclear cataracts, LECs were immunohistochemically positive for cytokeratin and vimentin, while those in anterior polar cataracts were positive for vimentin only. The LECs of anterior subcapsular cataracts were transdifferentiated into spindle-shaped fibroblast-like cells without cellular junctions and embedded within a fibrillar meshwork mass. The extracellular matrixes in the anterior capsule of anterior subcapsular cataracts were immunohistochemically positive for fibronectin, laminin, collagen type I, and collagen type IV. CONCLUSIONS: Lens epithelial cells in different types of cataracts have distinct cellular characteristics and may possess a bipotential nature with the ability to transdifferentiate into mesenchymal cells. This may be an underlying mechanism for the development of cataract and capsule opacification.     

白内障患者晶状体上皮细胞中Fas蛋白的表达

目的:了解不同类型白内障患者晶状体上皮细胞(lens epi-thelial cell,LECs)的凋亡情况及其与Fas蛋白(CD95)的关系。方法:取年龄相关性白内障、糖尿病性白内障及高度近视并发性白内障患者超声乳化手术中取下的前囊膜标本共73例。应用光镜、透射电镜及TUNEL标记法观察LECs的凋亡情况。同时应用免疫组化和流式细胞分别定性、定量检测Fas蛋白(CD95)在LECs中的表达。结果:光镜下3种白内障患者的LECs都呈透明样变性,细胞内有空泡。电镜下可见正常以及变性、坏死的LECs。部分LECs细胞内染色质凝集并边缘化,呈早期细胞凋亡改变。TUNEL检测发现3种白内障患者的LECs中均有TUNEL阳性细胞存在,LECs的凋亡率分别为(32.20±7.91)%、(31.00±9.43)%、(28.20±8.04)%,3种白内障间未见统计学差异。免疫组化结果表明在3种白内障患者的LECs中均有Fas蛋白(CD95)表达。流式细胞定量检测年龄相关性、糖尿病性及高度近视并发性白内障患者LECs中Fas蛋白(CD95)的表达量分别为(65.72±9.95)%、(63.46±13.30)%、(31.46±17.25)%,高度近视并发性白内障LECs中Fas蛋白(CD95)的表达与其他两种白内障间存在统计学差异(t检验,P<0.05)。结论:年龄相关性白内障、糖尿病性白内障及高度近视并发性白内障患者的LECs均出现凋亡,LECs的凋亡很可能是非先天性白内障发病的细胞病理学基础。Fas蛋白(CD95)介导的LECs的凋亡在年龄相关性白内障及糖尿病性白内障的形成中起重要的作用,而在高度近视并发性白内障LECs凋亡中可能存在其他通路。     

维拉帕米对人晶状体上皮细胞整合素表达的抑制作用

目的研究钙通道阻滞剂维拉帕米对人晶状体上皮细胞（LECs）株SRA01/04整合素表达的影响。方法对人LECs株SRA01/04进行培养并传代,分别以0.02、0.04、0.08mmol/L的维拉帕米作用于SRA01/0424h,经流式细胞仪检测SRA01/04各整合素的阳性表达率。结果整合素α2、α3、α5、β1、β2在人LECs株SRA01/04中呈阳性表达,维拉帕米对其表达具有抑制作用,并随药物浓度的增加而逐渐增强（P〈0.05）。结论钙通道阻滞剂维拉帕米对LECs整合素的表达具有抑制作用,可能阻碍整合素介导的LECs黏附、移行和增生,有望成为防治后发性白内障的有效药物。     

Effects of the cytokines on the proliferation of and collagen synthesis by human cataract lens epithelial cells.

AIMS: To assess the effects of the cytokines, interleukin-1 (IL-1), IL-1 receptor antagonist (IL-1ra), transforming growth factor-beta 2 (TGF-beta 2) and basic fibroblast growth factor (b-FGF), on the mitosis of and collagen synthesis by lens epithelial cells (LECs) of human cataracts. METHODS: The anterior lens capsule with attached LECs was obtained by capsulotomy during cataract surgery and cultured. The cultures at 2 to 3 weeks before confluency were used for the experiments. To quantify the mitosis and collagen synthesis, the incorporation of 3H-thymidine and 3H-proline, respectively, into the LECs was measured by a scintillation counter at 48 hours and 24 hours, respectively, after addition of the cytokine at various concentrations into the incubation medium. RESULTS: IL-1 and b-FGF increased the mitosis and collagen synthesis significantly, but IL-1ra significantly decreased the mitosis while leaving the collagen synthesis intact. TGF-beta 2 decreased the mitosis significantly, but increased the collagen synthesis significantly. CONCLUSION: These cytokines may play an important role in an autocrine or paracrine pathway in the proliferation of residual LECs after cataract surgery. Elucidation of the role of these cytokines may lead to the development of new therapies for the prevention of secondary cataract.     

Detection of tumor necrosis factor alpha and interleukin 1 alpha gene expression in human lens epithelial cells

PURPOSE: To analyze the gene expression of interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor alpha (TNF alpha) in human lens epithelial cells (LECs) by in situ RNA hybridization. SETTING: Department of Ophthalmology and Laboratory for Molecular Biology, Charité, Humboldt University, Berlin, Germany. METHODS: Anterior lens capsules with attached LECs were collected in RNase-free conditions from 10 consecutive patients during cataract surgery. Samples were then systematically analyzed by an in situ RNA-hybridization technique using specific gene probes for IL-1 alpha and TNF alpha, which were previously labeled with digoxigenin (DIG). RESULTS: The LECs tested positive for DIG-labeled gene probes in the described conditions. One (10%) patient showed a clearly detectable IL-1 alpha gene expression, and 7 (70%) showed a widely positive reaction for TNF alpha mRNA. CONCLUSION: The TNF alpha gene expression in LECs was more extended than that of IL-1 alpha in lens capsule samples from cataract surgery. Active synthesis of TNF alpha and IL-1 alpha may have consequences for postoperative inflammation and LEC proliferation.     

Activity of superoxide dismutase isoenzymes in lens epithelial cells derived from different types of age-related cataract

PURPOSE: To evaluate the level of superoxide dismutase (SOD) and SOD isoenzyme activity in lens epithelial cells (LECs) derived from different types of cataract in patients having phacoemulsification. SETTING: Iladevi Cataract & IOL Research Centre, Memnagar, Ahmedabad, India. METHODS: This observational study of 109 patients having phacoemulsification was performed to evaluate the level of activity in LECs of total superoxide dismutase (TSOD) and 2 superoxide dismutase isoenzymes: copper- (Cu) and zinc (Zn)-dependent SOD (Cu/Zn-SOD) and manganese (Mn)-dependent SOD (Mn-SOD). The curvilinear capsulorhexis (lens capsule) harboring LECs was obtained during phacoemulsification. The anterior lens capsule samples were processed for assaying SOD activity using the nitro blue tetrazolium reduction assay. The samples were grouped based on age and on pure cataract types. RESULTS: The highest level of TSOD, Cu/Zn-SOD, and Mn-SOD activity was in patients 50 years or younger. The activity declined gradually with age (P<.001). The level of TSOD activity increased in cortical cataract. The level of Cu/Zn-SOD and Mn-SOD isoenzyme activity in LECs was higher in cortical cataracts. A significant difference in the level of TSOD and Cu/Zn-SOD activity was found with different types of cataract (P<.001). CONCLUSIONS: The level of TSOD, Cu/Zn-SOD, and Mn SOD isoenzyme activity decreased with age in LECs of patients with age-related cataract. A significant difference in the level of TSOD and Cu/Zn-SOD isoenzyme activity between different types of cataract was observed. The activity of all 3 SOD isoenzymes was highest in cortical cataracts.     

Types of collagen synthesised by the lens epithelial cells of human cataracts.

AIMS/BACKGROUND--Residual lens epithelial cells (LECs) undergo fibrous proliferation after cataract surgery, resulting in capsular fibrosis. The purpose of this study was to determine the types of collagen produced in cultured LECs derived from human cataract LECs. METHODS--A circular section of the anterior capsule, about 5 mm in diameter, with LECs attached was obtained by anterior capsulotomy during cataract surgery and cultured directly without dispersion of the cells in a well, on the bottom of which a disc-shaped, thin plate of poly(methyl methacrylate) had been placed. At 5 to 6 weeks of culture, the proliferated cells of the culture were stained immunohistochemically with antibodies against human collagens I-VI by the avidin-biotin-peroxidase complex method. RESULTS--Collagens I, IV, V, and VI were positive in the cultured cells. Types IV and V were strongly present in almost all the cells whereas types I and VI were only observed in a few cells. Collagens II and III were negative. CONCLUSIONS--Since the lens capsule is known to be comprised of collagen IV, collagens I, V, and VI seem to be produced newly in culture. The capsular fibrosis seen after cataract surgery in vivo as a wound healing process of the lens capsule, may contain these types of collagens. The present culture model is useful for studying secondary cataract formation.     

Lens epithelial cell death after cataract surgery

PURPOSE: To determine whether lens epithelial cells (LECs) undergo apoptosis during healing after cataract surgery to further characterize the healing process of the postoperative lens capsule. SETTING: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. METHODS: Apoptotic cells were detected in human postoperative lens capsules using the terminal deoxynucleotidyl transferase deoxy-UTP nick-end labeling (TUNEL) method. The effect of exogenous transforming growth factor-beta2 (TGF-beta2) on mouse LEC apoptosis was also examined in an organ-culture system. RESULTS: Three of 17 postoperative specimens contained TUNEL-positive cells. In 2 lens capsules obtained earlier than 10 days, many TUNEL-positive cells, presumably apoptotic LECs, were observed beneath the residual anterior capsule. In cell multilayers in capsule opacification extracted later than 10 days, a few TUNEL-positive cells were seen in 1 specimen; most cells remained negative. In mouse lenses organ-cultured with 1.0 ng/mL TGF-beta2 for 48 hours, TUNEL-positive cells were detected beneath the lens capsule. CONCLUSIONS: Lens epithelial cells undergo apoptosis during healing after cataract surgery, especially in the early phase. Transforming growth factor-beta2 may be a factor inducing apoptosis in in vivo LECs.     

Expression of protein gene product 9.5 in the anterior lens epithelial cells of atopic cataracts

PURPOSE: To investigate the mechanisms of atopic cataract by immunohistochemically observing protein gene product 9.5 in lens epithelial cells (LECs) of atopic cataracts. SETTING: Departments of Ophthalmology and Anatomy, Shiga University of Medical Science, Shiga, Japan. METHODS: Specimens of anterior capsule obtained from 6 patients with atopic cataract and 8 patients with senile cataract were stained immunohistochemically and examined by light, electron, and confocal microscopy. RESULTS: In the LECs of the atopic cataracts, the arrangement and cell shape were varied. Immunohistochemistry for protein gene product 9.5 demonstrated selective localization, unlike with senile cataracts. This was especially prevalent in the spindle-shaped cells around the central opaque lesion. Protein gene product 9.5 positive cells overlapped with major basic protein positive cells in the atopic cataracts. CONCLUSIONS: The results indicate that the properties of LECs of atopic cataracts are different from those of senile cataracts. Protein gene product 9.5 and major basic protein seem to be concentrated in atopic cataracts.