可溶性CD44分子对人眼小梁网细胞凋亡调节蛋白bcl-2相关死亡因子bad表达的影响

背景 研究表明可溶性CD44分子(sCD44)在原发性开角型青光眼(POAG)患者眼中的质量浓度高于正常人,POAG患者房水中sCD44水平与小梁网细胞凋亡相关蛋白的表达是否有关及其对POAG的共同作用机制至今尚不明确. 目的 探讨不同质量浓度的sCD44对POAG患者小梁网细胞凋亡调节蛋白bcl-2相关死亡因子bad表达的影响.方法 收集POAG患者行小梁切除术中切除的小梁网组织,采用组织块培养法原代培养小梁网细胞,并用免疫细胞化学法对培养细胞进行鉴定,将第3代的小梁网细胞按随机数字表法随机分为6个组,分别在无血清培养基中加入含终质量浓度为0(对照组)、1、5、10、25、50 μg/L的sCD44,培养细胞48 h.采用细胞计数试剂8(CCK-8)法和ELISA法检测小梁网细胞中凋亡调节蛋白bc1-2相关死亡因子bad蛋白的表达.结果 培养的细胞经层黏连蛋白(LM)、神经元特异性烯醇化酶(NSE)单克隆抗体、纤维连接蛋白(FN)免疫组织化学染色呈阳性反应.CCK-8法检测0、l、5、10、25、50μg/L sCD44作用48 h后小梁网细胞吸光度(A450)值分别为:0.2460±0.0019、0.1874±0.0015、0.1570±0.0016、0.1302±0.0019、0.1084±0.0018、0.0940±0.0020,差异有统计学意义(F=14.922,P=0.000),各实验组A450值均低于对照组,差异均有统计学意义(P=0.013、0.008、0.011、0.005、0.004).ELISA法检测表明,0、l、5、10、25、50 μg/LsCD44作用48 h后小梁网细胞中bad蛋白质量浓度分别为(114.8461±2.9560)、(137.8270±2.4259)、(161.4194±3.7381)、(170.9453±3.2006)、(221.2252±4.3738)、(324.6167±4.4220) ng/L,差异有统计学意义(F=16.610,P=0.000),各实验组小梁网细胞中bad蛋白质量浓度均明显高于对照组,差异均有统计学意义(P=0.017、0.013、0.008、0.007、0.006).结论 sCD44在一定质量浓度范围内可促进POAG小梁网细胞的凋亡,并且能上调凋亡调节蛋白bcl-2相关死亡因子bad蛋白的表达.     

Presence of an established calcification marker in trabecular meshwork tissue of glaucoma donors

PURPOSE: To determine the presence of calcification markers in the trabecular meshwork tissue from glaucoma donors and in trabecular meshwork cells insulted by dexamethasone (DEX) and transforming growth factor beta2 (TGFbeta2), factors associated with glaucoma. To investigate as well the effect of silencing the inhibitor of calcification matrix Gla (MGP) in the trabecular meshwork cells. METHODS: Trabecular meshwork tissue was obtained from perfused postmortem anterior segments of glaucomatous and normal eyes. Primary trabecular meshwork cells were obtained from residual corneal rims after surgical corneal transplantation. Calcification marker alkaline phosphatase (ALP) enzyme activity was assayed by fluorescence produced after substrate cleavage. DNA quantification was evaluated by fluorescence produced after binding to the Hoechst dye. Transfection of siRNA to primary cells was accomplished by nucleofector electroporation with trabecular meshwork-optimized conditions. cDNA quantification was performed with the use of TaqMan real-time PCR. RESULTS: Human trabecular meshworks from glaucoma donors exhibited significantly higher levels of ALP activity than their matched counterparts with normal eyes. The normalized ALP of the control specimens was 7.3 +/- 1.6 ng ALP/microg DNA (n = 4), whereas that of the glaucomatous tissue was 37.0 +/- 10.7 ng ALP/microg genomic DNA (n = 5; P 相似文献   

Proteins secreted by human trabecular cells. Glucocorticoid and other effects

The capacity of cultured human trabecular meshwork (HTM) cells to secrete an extracellular matrix was studied by indirect immunofluorescence. Synthesis of nine extracellular matrix (ECM) proteins known to be present in the normal trabecular meshwork was assessed in three HTM cell lines. Fourteen primary antibodies were used and cultures were labeled two and four weeks after confluence. The HTM cell lines showed consistent labelling patterns for the normal extracellular connective tissue constituents including collagens (types I, III, IV, V and VI), glycoproteins (laminin and fibronectin) and a basement membrane-associated proteoglycan. These antigens were localized to the basal cell surface in an extracellular reticular pattern corresponding to cell margins. Dextran addition at confluence helped to intensify the staining of these components, but ascorbate had no apparent effect. Interestingly, elastin, another normal component of the trabecular meshwork, was not identified under standard conditions, or after addition of ascorbate or dextran. However, elastin could be detected intracellularly following dexamethasone treatment for three days, and extracellularly in punctate deposits when this treatment was used for 1 or 2 weeks. Our findings indicate that HTM cells may be responsible for the secretion and maintenance of all the major ECM constituents of the trabecular meshwork. The elastin results suggest a possible mechanism contributing to obstruction of outflow in steroid glaucoma if increased amounts of elastin are also produced in vivo. This approach can also serve as a useful baseline for comparison with HTM cell lines treated with glaucoma medications or obtained from patients with glaucoma.     

原发性开角型青光眼小梁细胞的体外培养及其生物学特性

背景原发性开角型青光眼（POAG）是一种常见致盲性眼病,其特点是房水外流阻力增加导致眼压增高。位于房水外流通道的小梁网调节房水的外流,因此研究小梁网细胞的生物学特性有着重要的意义。目的探讨POAG小梁细胞体外培养的方法及其生物学特性。方法经小梁切除术收集8例开角型青光眼患者患眼的带小梁网的深层巩膜组织块进行体外原代和传代培养,用鼠抗人层黏连蛋白（LM）单克隆抗体、兔抗人纤维连结蛋白（FN）单克隆抗体、鼠抗人神经元特异性烯醇化酶（NSE）单克隆抗体进行免疫组织化学检测以对传代细胞进行鉴定,在透射电子显微镜下对传代细胞的超微结构进行观察,并将传代小梁细胞的生物学特性与本研究组前期培养的正常小梁细胞进行比较。结果组织块培养10d左右,可见细胞从其边缘向外生长。传代细胞在4d内处于对数生长期,其后进入平台期,第7天细胞基本融合。第3代POAG小梁细胞及正常人眼小梁细胞中可见FN、LM和NSE均呈阳性表达,证实传代细胞为小梁细胞,而空白对照组细胞未见FN、LM和NSE表达。第3代POAG小梁细胞和正常小梁细胞中FN的A450值分别为0．354±0．06和0．26±0．01,LM的A450值分别为0．34±0．03和0．25±0．02,差异均有统计学意义（FN：t=14．446,P=0．001;LM：t=9．346,P=0．001）。与正常小梁细胞比较,第3代POAG小梁细胞表面的微绒毛、细胞质的溶酶体及吞噬小泡含量减少。结论采用组织块培养法可成功在体外培养POAG小梁细胞,该研究结果为研究青光眼的发病机制提供了细胞学基础。     

Ultrastructural localization of collagen IV, fibronectin, and laminin in the trabecular meshwork of normal and glaucomatous eyes.

PURPOSE: To determine whether differences in the ultrastructural characteristics or composition of the basement membranes of the trabecular lamellae and Schlemm's canal exist in normal eyes and eyes with primary open-angle glaucoma (POAG). Basement membranes play key roles in the attachment of the overlying trabecular cells and Schlemm's canal cells. METHODS: Electron microscopy used in conjunction with immunogold labeling was used to examine the ultrastructure of the basement membranes in the trabecular meshwork and to determine the presence of collagen IV, laminin, and fibronectin in 6 normal eyes and 6 eyes with POAG. To determine which cells in the meshwork synthesized these molecules in situ hybridization was studied in an additional 8 normal eyes. RESULTS: No distinctive ultrastructural changes were found in the basement membranes of glaucomatous eyes, whether early or advanced disease, when compared with normal eyes. Label for all three proteins was present in the basement membranes of the trabecular lamellae, Schlemm's canal, and in scattered patches within the juxtacanalicular tissue. Laminin and fibronectin were most abundant in the periphery of the sheath material surrounding the elastic tendons in the juxtacanalicular tissue. In contrast to previously published light microscopic studies, no increase in fibronectin was found in glaucoma. Regions of the basement membrane of the canal underlying giant vacuoles were similar to regions without giant vacuoles in both appearance and labeling. In situ hybridization revealed that mRNA for all three proteins was present in most trabecular cells throughout the meshwork; no regional differences in cellular labeling within were observed. CONCLUSION: The ultrastructural characteristics and immunogold labeling of basement membranes were similar in normal and glaucomatous eyes; no additional structures were labeled in POAG eyes that were not also labeled in normal eyes. Label of the patches of amorphous fibrogranular material within the juxtacanalicular tissue suggests it is basement membrane in origin, while the sheath material which is known to accumulate in POAG was not heavily labeled and does not appear to be basement membrane in origin.     

反义CD44基因转染对人眼小梁细胞合成细胞外基质的影响

目的：观察反义CD44基因转染对人眼小梁细胞合成细胞外基质的影响,探讨黏附分子CD44在原发性开角型青光眼(primary open angle glaucoma, POAG)发病过程中可能的作用。 方法：采用硫代修饰的CD44反义寡核苷酸,通过脂质体介导转染体外培养的人眼小梁细胞,免疫组织化学染色观察CD44反义寡核苷酸对小梁细胞合成胶原蛋白Ⅰ型、层黏附蛋白的影响,放射免疫法观察CD44反义寡核苷酸对小梁细胞合成透明质酸的影响。 结果：CD44反义寡核苷酸对人眼小梁细胞合成胶原蛋白Ⅰ型、层黏附蛋白起促进作用,且呈浓度依赖性,浓度越高促分泌作用越强,但对小梁细胞合成透明质酸起抑制作用,浓度越高抑制作用越明显。 结论：CD44反义寡核苷酸封闭CD44基因表达后人眼小梁细胞合成胶原蛋白Ⅰ型、层黏附蛋白增加而合成透明质酸减少。黏附分子CD44可能通过影响小梁细胞合成细胞外基质功能参与了POAG发病过程。     

水通道蛋白-1在小梁切除术之切除组织中的表达

目的观察青光跟患者小梁和虹膜组织与正常跟组织水通道蛋白-1（AQP-1）的表达差异。方法收集开角型和闭角型青光跟小梁切除术时切除的小梁和虹膜组织，免疫组织化学法检测AQP-1的表达，并与正常跟相应组织对照。结果正常眼小梁网组织、Schlemm’s管内皮细胞、周边虹膜组织中上皮和基质组织可见AQP-1呈强阳性着色，开角型青光眼和闭角型青光眼组织标本小梁网AQP-1阳性染色较正常弱；部分急性闭角型青光眼患者周边虹膜组织标本上皮层较基质组织染色明显弱。结论开角型青光眼小梁网AQP-1的表达减少可能与小梁网的发育有关，闭角型青光眼虹膜上皮和小梁网AQP-1的表达减少可能与虹膜萎缩或高眼压有关。     

Localization by immunogold of collagen VI, laminin and fibrillin in the trabecular meshwork of patients with glaucoma

PURPOSE: To localize the collagen type VI, laminin et fibrillin in glaucomatous and non-glaucomatous trabecular meshworks. MATERIAL: Twenty-four trabeculectomy specimens from patients suffering of primary open angle glaucoma (POAG, 15 cases), pigmentary glaucoma (PG, 2 cases), pseudo-exfoliative glaucoma (PEG, 7 cases) and 2 non glaucomatous aged trabeculums of enucleated eyes. METHODS: Post-embedding immunogold indirect labelings on 4% paraformaldehyde-0.1% glutaraldehyde fixed and LRWhite embedded samples. RESULTS: Labeling of type VI collagen was observed on the 64 nm collagen fibers in all samples, less intensively on POAG or PG disorganised microfibril areas, and especially on PEG pseudo-exfoliative material deposits. Laminin labeling was strongly positive on healthy basal membranes and less intense on POAG and PG abnormal basal membranes. Fibrillin labeling was found on POAG or PG disorganized microfibril areas, especially around pigment granules, around 64 nm striated collagen fibers and with a mild intensity on POAG and PG juxtacanalicular microgranular substance areas. No labeling was found on pseudo-exfoliative substance deposits. CONCLUSION: Collagen type VI abundance in pseudo-exfoliative substance deposits could result from a fibrillogenesis abnormality. POAG and PG basal membrane ultrastructural abnormalities and weak laminin content could share the origin. The abundance of fibrillin in disorganized microfibrils could result from the chronic elevated tensile strength due to ocular hypertony.     

原发性开角型青光眼铁死亡相关基因表达谱的生物信息学分析

目的：通过生物信息学手段分析原发性开角型青光眼(POAG)进展过程中调控铁死亡相关的关键基因，旨在进一步揭示铁死亡在POAG中的生物学机制。

方法：从GEO数据库中获取小梁网来源的GSE27276数据集，其中包括19个POAG小梁网组织样本和17个正常小梁网组织样本； 下载FerrDb数据库整理的铁死亡相关基因，将GSE27276数据集与铁死亡基因集进行映射，筛选POAG中铁死亡相关的预后差异表达基因(DE-FRGs)并进行相关性分析，进一步了解DE-FRGs的GO和KEGG通路富集。应用LASSO回归模型与SVM-RFE模型两种机器学习的算法筛选铁死亡相关POAG的关键基因，将两种模型的筛选结果取交集，获得最佳特征基因，使用受试者特征曲线(ROC)评估临床诊断能力； 对最佳特征基因进行单基因基因组富集分析(GSEA)和变异分析(GSVA)； 借助视乳头来源的GSE2378与GSE9944数据集验证最佳特征基因的表达水平。

结果：与正常小梁网组织相比，POAG的小梁网组织有396个铁死亡基因存在差异表达，其中39个为上调基因，64个为下调基因，Spearman相关性分析显示上调基因和下调基因均有一定的相关性。GO功能和KEGG通路富集分析显示，差异基因主要富集在氧化应激反应和铁死亡通路； 通过LASSO和SVM-RFE算法将18个DE-FRGs确定为关键基因，具有更高的诊断价值。GSEA和GSVA富集分析显示GDF15、MFN2和OTUB1基因与谷胱甘肽代谢通路密切相关，其中MFN2和OTUB1分别在高表达组和低表达组中激活谷胱甘肽代谢通路。GSE2378与GSE9944数据集交叉验证明确视乳头标本中CREB1的表达水平相对于正常视乳头样本显著升高，这与GSE27276数据集小梁网样本表达一致。

结论：基于生物信息学分析挖掘得到396个POAG的DE-FRGs，通过构建机器筛选模型和外部数据集交叉验证，筛选出CREB1有望成为潜在诊断生物标志物的最佳特征基因，为进一步深入阐明POAG铁死亡相关的分子机制和诊断提供靶点。同时筛选的基因还需要进一步体内、外实验验证，揭示铁死亡在POAG中的生物学机制。     

高糖对牛眼小梁细胞形态、增殖及凋亡的影响

目的:建立牛眼小梁细胞体外培养体系,观察高浓度葡萄糖对小梁细胞的影响,研究高糖与开角型青光眼(primary open angle glaucoma,POAG)以及糖尿病与POAG之间的关系,探讨糖尿病开角型青光眼的发病机制,从而为指导开角型青光眼的临床用药提供重要依据。方法:以新鲜牛眼为材料,分离并培养小梁细胞,用光学镜、电镜观察正常小梁细胞的形态。将传至第3代的小梁细胞制作成细胞悬液、计数并接种于培养板(或培养瓶)中,待细胞贴壁后,将细胞分为两组:对照组(葡萄糖浓度为5.5mmol/L)和高糖组(葡萄糖浓度为35mmol/L),分别培养7d后收集细胞,用透射电子显微镜、MTT法、流式细胞仪(FCM)检测法,研究高糖对小梁细胞形态、增殖和凋亡的影响。结果:高糖组与对照组相比较,小梁细胞胞浆内细胞器减少,内质网、高尔基复合体、线粒体等细胞器肿胀,溶酶体及脂肪滴增多,核浆比减小,可见凋亡小体;高浓度葡萄糖对小梁细胞的增殖有明显的抑制作用,能够促进小梁细胞的凋亡,均有统计学意义(P<0.05)。结论:高糖可能通过使小梁细胞的增殖能力下降,凋亡率增加,使近管小梁网的网状结构改变,网孔变小,改变房水流出途径的阻力导致眼内压升高,可能是糖尿病患者PO-AG发病率增高的原因之一。     

Aqueous humor stimulates the migration of human trabecular meshwork cells in vitro

PURPOSE: Depletion of trabecular meshwork cell numbers is a feature of the outflow system in aging and in primary open-angle glaucoma. It is possible that migration stimulated by factors present in aqueous humor may contribute to the cell loss. This investigation assessed the chemoattractant potential of glaucomatous and nonglaucomatous human aqueous humor and fibronectin, one of its constituents, on a range of cultured trabecular meshwork cell lines. METHODS: Migration was assessed in 48-well modified Boyden chambers. The potential migratory stimulants were soluble fibronectin and glaucomatous and nonglaucomatous aqueous humor. The glaucomatous aqueous samples were collected from patients undergoing trabeculotomy for primary open-angle glaucoma and the normal aqueous from normal bovine eyes and patients undergoing cataract surgery. The target cell types were normal human and bovine meshwork cells grown from explants and two human transformed meshwork cell lines from a normal (HTM-5) and a glaucomatous (HTM-3) source. RESULTS: Soluble fibronectin stimulated all the target cells to migrate with an optimal concentration ranging from 1 to 30 microg/ml, and Zigmond Hirsch checkerboard analysis indicated that both chemotaxis and chemokinesis took place. All the aqueous humor samples stimulated migration of the meshwork cell lines at an optimal concentration of 200 microl/ml. Glaucomatous aqueous humor stimulated a greater migratory response than nonglaucomatous aqueous for two of the four target cell types (P < or = 0.03). Neutralization of the fibronectin content of nonglaucomatous and glaucomatous aqueous by addition of excess anti-fibronectin antibody indicated that fibronectin could account for 35% to 80% of the migratory activity of the aqueous. CONCLUSIONS: Aqueous humor contains potentially powerful chemoattractants for trabecular meshwork cells. The activity of one of these constituents, fibronectin, has been accounted for by this study. Glaucomatous aqueous appears to be as good and in some cases a better migratory stimulant than nonglaucomatous aqueous in vitro. The migratory evidence points to a trend that may help to explain cell loss in the aging meshwork and possibly some of the extra loss in primary open-angle glaucoma.     

The myocilin (MYOC) gene expression in the human trabecular meshwork

PURPOSE: We previously reported a novel cytoskeletal protein with a myosin-like domain which is localized in the ciliary rootlet and basal body of connecting cilium of photoreceptor and hence we named it 'myocilin'. It was soon realized that myocilin is identical to a protein called TIGR (trabecular meshwork inducible glucocorticoid response protein) which was found to be responsible for the pathogenesis of juvenile open angle glaucoma. In this study, we employed in situ RNA hybridization to examine the myocilin (MYOC)/ TIGR gene expression in the trabecular meshworks of glaucomatous and nonglaucomatous eyes. METHODS: The glaucomatous specimens were obtained by trabeculectomy from the patients with primary open angle glaucoma (POAG), chronic angle closure glaucoma (CACG) and steroid glaucoma, respectively, and the nonglaucomatous specimens were obtained from a victim of traffic accident at autopsy and from a patient with maxillary sinus carcinoma at enucleation for the operation. The in situ RNA hybridization was carried out with digoxigenin-labeled sense and antisense RNA probes. RESULTS: In all cases, hybridization signals were detected primarily in the trabecular meshwork cells and secondarily in the fibroblast-like cells of corneoscleral wall. CONCLUSIONS: Myocilin gene is expressed clearly in the trabecular meshwork cells of both glaucomatous and nonglaucomatous eyes.     

Scanning electron microscopy of the trabecular meshwork: understanding the pathogenesis of primary angle closure glaucoma

Purpose:

To study ultrastructural changes of the trabecular meshwork in acute and chronic primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) eyes by scanning electron microscopy.

Materials and Methods:

Twenty-one trabecular meshwork surgical specimens from consecutive glaucomatous eyes after a trabeculectomy and five postmortem corneoscleral specimens were fixed immediately in Karnovsky solution. The tissues were washed in 0.1 M phosphate buffer saline, post-fixed in 1% osmium tetraoxide, dehydrated in acetone series (30-100%), dried and mounted.

Results:

Normal trabecular tissue showed well-defined, thin, cylindrical uveal trabecular beams with many large spaces, overlying flatter corneoscleral beams and numerous smaller spaces. In acute PACG eyes, the trabecular meshwork showed grossly swollen, irregular trabecular endothelial cells with intercellular and occasional basal separation with few spaces. Numerous activated macrophages, leucocytes and amorphous debris were present. Chronic PACG eyes had a few, thickened posterior uveal trabecular beams visible. A homogenous deposit covered the anterior uveal trabeculae and spaces. Converging, fan-shaped trabecular beam configuration corresponded to gonioscopic areas of peripheral anterior synechiae. In POAG eyes, anterior uveal trabecular beams were thin and strap-like, while those posteriorly were wide, with a homogenous deposit covering and bridging intertrabecular spaces, especially posteriorly. Underlying corneoscleral trabecular layers and spaces were visualized in some areas.

Conclusions:

In acute PACG a marked edema of the endothelium probably contributes for the acute and marked intraocular pressure (IOP) elevation. Chronically raised IOP in chronic PACG and POAG probably results, at least in part, from decreased aqueous outflow secondary to widening and fusion of adjacent trabecular beams, together with the homogenous deposit enmeshing trabecular beams and spaces.     

细胞外基质重塑在原发性开角型青光眼的作用及研究进展

青光眼是一组以特征性视神经萎缩和视野缺损为共同特征的疾病,病理性眼压增高是其主要危险因素。视网膜神经节细胞( retinal ganglion cells, RGCs)凋亡及其轴突丢失是青光眼的主要病理特征。细胞外基质( extracellular matrix, ECM)含量和成分的变化对小梁网构型、视乳头筛板结构、RGCs凋亡起着决定性作用。青光眼患者小梁网及房水中转化生长因子-β2( transforming growth factor-β2,TGF-β2)增加,引起ECM分泌增加和堆积导致眼压升高;高眼压引起视神经乳头ECM成分的改变,引起神经营养因子剥夺,导致RGCs凋亡;同时,高眼压引起视网膜基质金属蛋白酶类-9(matrix metalloproteinase-9,MMPs-9)活性增加,层连黏蛋白的减少又将导致 RGCs 凋亡的增加。因此,研究ECM和青光眼的关系至关重要,可能为原发性开角型青光眼发病机制及治疗提供新的方向。     

Regulation of glucocorticoid responsiveness in glaucomatous trabecular meshwork cells by glucocorticoid receptor-beta

PURPOSE: Glucocorticoid administration can lead to increased intraocular pressure in greater than 90% of patients with primary open-angle glaucoma (POAG), compared with 30% to 40% of the general population. The molecular mechanisms for increased steroid responsiveness among patients with glaucoma are unknown. An alternative splicing variant of the human glucocorticoid receptor GRbeta has dominant negative activity and has been implicated in a variety of steroid-resistant diseases. GRbeta also may play a role in glucocorticoid hyperresponsiveness in glaucoma. METHODS: Western blot analysis was performed to detect the expression of GRalpha and GRbeta in TM cells and its regulation by dexamethasone (DEX). Immunocytochemistry was used to compare the subcellular expression of GRbeta between normal and glaucomatous TM cell lines. DEX transgene induction in a luciferase reporter was performed to investigate the differential glucocorticoid responsiveness between multiple normal and glaucomatous TM cell lines. Overexpression of GRbeta was conducted in glaucomatous TM cell lines, and the regulation of GRbeta in the Dex-induced reporter gene luciferase or endogenous myocilin and fibronectin expression were determined. RESULTS: Trabecular meshwork (TM) cell lines derived from normal individuals expressed higher levels of GRbeta than did glaucomatous TM cells. Glaucomatous TM cells were more susceptible to DEX induction of a luciferase reporter gene than were TM cells derived from normal donors. Overexpression of GRbeta in glaucomatous TM cells inhibited DEX induction of a luciferase reporter gene as well as the endogenous genes MYOC and fibronectin. CONCLUSIONS: The decreased amount of GRbeta in glaucomatous TM cells could result in enhanced glucocorticoid responsiveness and ocular hypertension.     

Expression of CD44 in Cultured Human Trabecular Meshwork Cells

Asoneofthemajordiseasesthatcauseofblindness,primaryopen鄄angleglaucoma(POAG)hasnotbeenunderstoodverywellyet[1].Trabecularmeshwork(TM)whichismainlycom鄄posedoftrabecularbeamsandtrabecularmesh鄄workcellsisthoughttofunctionasaself鄄cleaningfilterandtocontributetotheregulationofaque鄄oushumoroutflow.ItisknownthatTMcellslin鄄ingthebeamsplayanessentialroleinmainte鄄nanceofthenormaloutflowsystem.AvarietyofcellsorbiochemicalfactorsmaybeinvolvedinPOAG.Changesofcellsorbiochemicalfactorsresultedince…     

Effect of high glucose on fibronectin expression and cell proliferation in trabecular meshwork cells.

PURPOSE: Increased fibronectin accumulation in the trabecular meshwork of glaucomatous eyes may contribute to the resistance of aqueous outflow and the development of primary open-angle glaucoma (POAG). Because the glucose level is increased in the aqueous humor of patients with diabetes, this study was conducted to determine whether a high-glucose condition alters fibronectin expression and contributes to cell loss in trabecular meshwork. METHODS: The fibronectin mRNA level was determined using RT-PCR in bovine trabecular meshwork cells grown in normal (5 mM) or high (30 mM)-glucose medium for 7 days, and cell counts were measured during this period. Distribution and the relative amount of fibronectin protein were determined in these cells by immunofluorescence microscopy and Western blot analysis. RESULTS: Fibronectin mRNA level in cells grown in high-glucose medium was significantly upregulated two- to threefold compared with cells grown in normal medium (P < 0.05). In cells grown in high-glucose medium, fibronectin immunofluorescence was more intense, and the relative amount of fibronectin protein was significantly increased (131% +/- 15% of control, P < 0.05) compared with the amount in cells grown in normal medium. A moderate decrease in cell number was observed in cells grown in high-glucose medium (78% +/- 7% of control, P < 0.05) CONCLUSIONS: These findings indicate that a high glucose level in aqueous humor of patients with diabetes may increase fibronectin syntheses and accumulation in trabecular meshwork and accelerate the depletion of trabecular meshwork cells, a characteristic feature of the outflow system in POAG. The striking similarity between high glucose-induced alterations in trabecular meshwork cells and those of vascular endothelial cells may represent a common biochemical link in the pathogenesis of POAG and diabetic microangiopathy.     

Effect of excess synthesis of extracellular matrix components by trabecular meshwork cells: possible consequence on aqueous outflow

The extracellular matrix (ECM) of the trabecular meshwork (TM) is an important determinant of its functional properties. This study was performed to investigate whether overexpression of ECM components, laminin (LM) and collagen type IV (Col) by TM cells may play a role in the development of outflow resistance. To determine the effect of excess LM and Col expression on cell monolayer permeability, an in vitro cell culture model was used in which overexpression of the two ECM components, LM and Col, was induced by high glucose (HG) (30 mM) or 0.1 microM dexamethasone (D) in bovine and human trabecular meshwork (BTM and HTM) cells. Western blot analysis and immunofluorescence staining confirmed increased LM and Col synthesis in cells exposed to HG or D. Increased level of LM and Col protein resulted in reduced cell monolayer permeability. Transfection with antisense oligos (AS-oligos) targeted against LM or Col inhibited HG- or D-induced LM and Col gene overexpression in TM cells with concomitant increase in permeability. The AS-oligo strategy was effective in reducing LM or Col level in the TM cells in all conditions tested in this study. These findings suggest that increased LM and Col deposition in the outflow pathway may cause resistance to aqueous outflow and contribute to the development of primary open angle glaucoma (POAG).