基质金属蛋白酶及其抑制剂在眼表疾病发病机制研究中的进展

基质金属蛋白酶(matrix metalloproteinases,MMPs)是一组降解细胞外基质的内源性蛋白酶系,其与基质金属蛋白酶组织抑制剂(tissue inhibitor of metalloproteinases,TIMPs)组成MMPs/TIMPs系统,降解和重塑细胞外基质.MMPs/TIMPs系统表达水平的失衡与眼病的发生发展密切关联,尤其是在各类眼表疾病中.目前认为结膜成纤维细胞中MMP-1、MMP-3及MMP-9过度表达是引起MMPs与TIMPs之间失去平衡的关键因素.MMPs与TIMPs之间失去平衡,使胶原纤维融解,弹力纤维变性减少,导致球结膜基质和Tenon囊的过度降解,引起眼表泪液异常的病理循环.眼表泪液的异常破坏了眼表环境的稳定性,参与多个眼表疾病如干眼、结膜松弛症、翼状胬肉、角膜炎等的病理变化.     

小梁细胞基质金属蛋白酶及其调控因素

基质金属蛋白酶(MMPs)是一组降解细胞外基质(ECM)成分的含锌蛋白水解酶家族,对于维持ECM不断产生与降解的动态平衡及正常房水通路的流畅性具有重要的意义.基质金属蛋白酶抑制剂(TIMPs)是MMPs的内源性特异性的组织抑制剂,可以抑制MMPs对ECM的降解作用.MMPs活性受多种水平调节,分为基因水平、酶原活化调节、活化后调节.因此各种外界因素、MMPs及其组织抑制因子TIMPs共同参与ECM的降解与重建,它们之间的协同作用以及表达的动态平衡保证组织的正常生理功能运转.就小梁细胞MMPs及其多种调控因素进行综述.     

三种视网膜病视网膜前膜中基质金属蛋白酶及其天然抑制分子的表达

目的 研究增殖性糖尿病视网膜病变(proliferative diabetic retinopathy,PDR)、增殖性玻璃体视网膜疾病(proliferative vitreoretinopathy,PVR)和急性视网膜坏死(acute retinalnecrosis,ARN)患者视网膜前膜中基质金属蛋白酶(matrixmetalloproteinases:MMPs)及其天然抑制物(tissueinhibitorsofmetalloproteinages,TIMPs)的表达情况.方法 玻璃体手术中剥取PVR、PDR和ARN患者的视网膜前膜,同供体眼视网膜作为正常对照,冰冻切片后进行免疫组织化学染色,包括:MMP-1,MMP-2,MMP-3,MMP-7,MMP-9,TIMP-1和TIMP-2.结果 正常视网膜中能够观察到MMP-1,MMP-3,TIMP-1和TIMP-2的表达,在PVR、PDR和ARN患者标本中各种分子的表达都增强,尤以MMP-2,MMP-3和MMP-7明显.结论 正常视网膜中存在MMPs和TIMPs分子维持着细胞外基质动态的平衡,在PVR,PDR和ARN患者中MMP-2,MMP-3和MMP-7等MMPs分子表达增强,在其病变过程中可能起重要作用.     

基质金属蛋白酶及其抑制剂与眼部疾病

基质金属蛋白酶(MMPs)是一组锌离子依赖性内肽酶，其主要功能是降解细胞外基质，在细胞迁移、组织重建和修复等病理生理过程中发挥作用。MMPs的蛋白水解活性主要靠与其抑制剂TIMPs之间的平衡来调节。尽管MMPs和TIMPs参与的具体机理尚未明确，但对于寻找角膜炎、白内障、青光眼及增生性玻璃体视网膜病变等眼病的发病机理有重要意义。本文综述了MMPs、TIMPs在眼病中的表达变化及作用。     

MMPs/TIMPs在近视发生发展中的机制研究进展

近年来近视的发病率逐年增高。多项针对近视动物模型的实验及人体临床研究均表明基质金属蛋白酶（MMPs）及其抑制剂基质金属蛋白酶抑制剂（TIMPs）在近视发生发展中发挥着重要作用。笔者从基因表达、mRNA水平、蛋白质浓度等多个方面探讨了MMPs/TIMPs对巩膜及眼内其他组织的影响，并对其与近视发生机制的关系作一总结。     

基质金属蛋白酶及其组织抑制剂与白内障

基质金属蛋白酶(matrixmetalloproteinases,MMPs)是一类金属依赖的水解酶家族,是细胞外基质(extracelluarmatrix,ECM)降解的主要介质,其主要功能是降解细胞外基质,在细胞迁移、组织重建和修复等病理生理过程中发挥作用。MMPs的蛋白水解活性主要靠与其抑制剂(tissueinhibitorofMMPs,TIMPs)之间平衡来调节。近年来研究表明,MMPs/TIMPs功能异常同眼部许多疾病有关,如原发开角型青光眼、白内障、翼状胬肉、年龄相关性黄斑变性等有关。     

基质金属蛋白酶及其组织抑制因子与后发性白内障

基质金属蛋白酶(matrix metalloproteinases,MMPs)是一类金属依赖的水解酶家族,是细胞外基(extracelluar matrix,ECM)降解的主要介质,其主要功能是降解细胞外基质,在细胞迁移、组织重建和修复等病理生理过程中发挥作用。MMPs的蛋白水解活性主要靠与其抑制剂(tissueinhibitor of MMPs,TIMPs)之间平衡来调节。组织中MMPs与TIMPs之间保持着相对平衡状态,它们的平衡和相互影响决定着细胞外基质是降解还是聚集。ECM不但可作为晶状体上皮细胞(LECs)生长增殖的支架,而且还起促进LECs增殖、移行和黏附作用,最终导致晶状体后囊膜的混浊和纤维化。     

小鼠单纯疱疹病毒性角膜炎中基质金属蛋白酶的表达及活性研究

目的 探讨角膜感染Ⅰ型单纯疱疹病毒(HSV-1)后基质金属蛋白酶(MMPs)及其组织抑制剂(TIMPs)在角膜中的分布及酶活性表达。方法 BALB／c小鼠眼角膜接种HSV-1(KOS株)以诱发单纯疱疹病毒性角膜炎(HSK)。分别收集正常眼球及感染后第2、7、14及28天的感染眼球。应用免疫组织化学法和Western blot方法检测MMP-2、-8、-9及TIMP-1、-2在角膜组织中的表达,并应用酶谱(Zymography)技术检测MMPs的酶活性。结果 感染后第2天,感染眼的MMP-2、-9及TIMP-1、-2表达比未感染眼增加且表达主要位于浅表基质层及上皮下的炎性细胞中。感染后第14和28天可见坏死性角膜炎及角膜溃疡形成,同时角膜基质和浸润的炎性细胞中尤其溃疡处,可见MMP-2、-9及TIMP-1、-2表达显著增加。溃疡区域有大量MMP-8阳性染色的中性粒细胞。角膜感染HSV-1后,明胶酶(MMP-2、-9)活性和胶原酶(MMP-8)活性均增强。结论 HSV-1角膜感染后,由角膜细胞和浸润的炎性细胞分泌产生的MMPs可能对上皮性角膜炎与溃疡形成过程起重要的促进作用。MMPs与TIMPs的相互作用可能对HSK的坏死性病变起重要调节作用。（中华眼科杂志,2004,40：395-399)     

基质金属蛋白酶和组织金属蛋白酶抑制剂在年龄相关性黄斑变性发病中的作用

年龄相关性黄斑变性(AMD)是导致老年人中心视力丧失的主要视网膜疾病之一,其发病机制目前尚未完全清楚.近年来的临床研究和基础研究表明,受基质金属蛋白酶(MMPs)和组织金属蛋白酶抑制剂(TIMPs)调控的细胞外基质(ECM)的代谢障碍在AMD的发病过程中起重要作用.研究表明,MMPs与TIMPs平衡的失调导致Bruch膜不同的病理性改变,参与玻璃膜疣的形成,调控脉络膜新生血管(CNV)的形成；而ECM降解产物弹性蛋白衍生肽(EDPs)的水平反映了MMPs水平及其活性,EDPs水平的升高可增加早期AMD向新生血管性AMD转化的风险.就MMPs和TIMPs及ECM降解产物EDPs在AMD发病机制中的研究进展进行综述.     

IL-1α对体外培养的牛小梁网细胞MMPs及TIMPs表达的影响

目的 观察白细胞介素-1α（IL-1α）对体外培养的牛小梁网细胞分泌基质金属蛋白酶（MMPs）和基质金属蛋白酶组织抑制剂（TIMPs）的影响，探讨IL-1α降低眼压的机制。方法 采用酶谱分析法和反向酶谱分析法检测牛小梁网细胞MMP和TIMPs的分泌，并观察IL-1α对MMP和TIMPs分泌的调节作用。结果 体外培养的牛小梁细胞分泌MMP-2、MMP-3、MMP-9和TIMP-1；IL-1α对MMP-2、MMP-3、MMP-9的分泌有促进作用，且呈时间和浓度依赖性，其中以IL-1α对MMP-3的分泌促进作用最强；IL-1α对TIMP-1的分泌也有微小的增加作用。结论 IL-1α能够显著促进牛小梁网细胞分泌MMPs，打破了MMP／TIMPs的平衡，可能进一步促进小粱网细胞外基质（ECM）的分解，增强房水流动性。     

Understanding the complexity of the matrix metalloproteinase system and its relevance to age-related diseases: Age-related macular degeneration and Alzheimer's disease

Extracellular matrices (ECMs) are maintained by tightly coupled processes of continuous synthesis and degradation. The degradative arm is mediated by a family of proteolytic enzymes called the matrix metalloproteinases (MMPs). These enzymes are released as latent proteins (pro-MMPs) and on activation are capable of degrading most components of an ECM. Activity of these enzymes is checked by the presence of tissue inhibitors of MMPs (TIMPs) and current opinion holds that the ratio of TIMPs/MMPs determines the relative rate of degradation. Thus, elevated ratios are thought to compromise degradation leading to the accumulation of abnormal ECM material, whilst diminished ratios are thought to lead to excessive ECM degradation (facilitating angiogenesis and the spread of cancer cells).Our recent work has shown this system to be far more complex. MMP species tend to undergo covalent modification leading to homo- and hetero-dimerization and aggregation resulting in the formation of very large macromolecular weight MMP complexes (LMMCs). In addition, the various MMP species also show a bound-free compartmentalisation. The net result of these changes is to reduce the availability of the latent forms of MMPs for the activation process. An assessment of the degradation potential of the MMP system in any tissue must therefore take into account the degree of sequestration of the latent MMP species, a protocol that has not previously been addressed. Taking into consideration the complexities already described, we will present an analysis of the MMP system in two common neurodegenerative disorders, namely age-related macular degeneration (AMD) and Alzheimer's disease (AD).     

Modulation of matrix metalloproteinase and TIMP-1 expression by cytokines in human RPE cells

PURPOSE: The balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) is crucial for homeostasis of ocular extracellular matrices. To assess altered MMP activity as a determinant in the migration of human retinal pigment epithelial (RPE) cells, expression characteristics of several MMPs and TIMP-1 in RPE cell cultures were investigated. METHODS: Expression studies were performed with RT-PCR, ELISA, and immunofluorescence analysis. Secretion of MMP-2 was demonstrated by zymography. Migration of cytokine-stimulated RPE cells was evaluated with microporous membranes of permeable chambers. RESULTS: MMP-1, -2, -3, and -9; MT2-MMP; and TIMP-1 were expressed in cultured RPE cells. MMP-2 was detected on the cell surface and in secreted inactive and active forms. TGF-beta(2), IL-1beta, and TNF-alpha enhanced secretion of MMP-1, -2, and -3. TGF-beta(2) also stimulated MT2-MMP cell surface expression and release of TIMP-1. The mRNA levels of MMP-1, -2, and -3 and TIMP-1 were markedly increased by TNF-alpha and TGF-beta(2). MMP-2 mRNA levels were also upregulated by PDGF-BB. Migration of RPE cells stimulated by TGF-beta(2) or PDGF-BB was inhibited in presence of a synthetic MMP inhibitor. CONCLUSIONS: Proinflammatory cytokines and TGF-beta(2) play an important role in the upregulation of expression of MMP-1, -2, and -3 in RPE cells and account for a directional shift in the balance between MMPs and TIMPs. Facilitation of RPE cell migration stimulated by cytokines (i.e., TGF-beta(2) or PDGF-BB) in ocular diseases may be due to increased release of MMPs, in the presence of comparatively lower levels of their inhibitors.     

基质金属蛋白酶/基质金属蛋白酶组织抑制剂系统与糖尿病眼部并发症

基质金属蛋白酶/基质金属蛋白酶组织抑制剂（MMPs/TIMPs）系统是降解和重塑细胞外基质（ECM）最重要的酶系统,它参与调节眼的一些生理和病理过程,如眼的发育、炎症、伤口愈合、新生血管形成、肿瘤转移等,与多种眼病,如增生性玻璃体视网膜病变、增生型糖尿病视网膜病变、糖尿病性白内障、孔源性视网膜脱离、视网膜母细胞瘤、年龄相关性黄斑变性、眼外伤、青光跟等的发生密切相关.就MMPs/TIMPs系统的生物学特性及其在糖尿病眼部并发症研究方面的应用进行综述.     

Expression of matrix metalloproteinases 2 and 9 and tissue inhibitors of metalloproteinase 1 and 2 in inflammation-induced corneal neovascularization.

PURPOSE: Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) have been linked to the angiogenic process in general. In order to understand the potential roles of MMP-2, MMP-9 and TIMPs in the corneal neovascularization process, we examined the expression and activities of MMP-2, MMP-9 and TIMPs during the course of cauterization-induced corneal neovascularization in a rat model. METHODS: Neovascularization of rat corneas was induced by silver nitrate cauterization. The expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 was examined by immunohistochemistry and RT-PCR. The protein activities of MMPs and TIMPs were compared in pre- and postcauterization corneas by gelatin zymography and reverse zymography, respectively. RESULTS: MMP-2, TIMP-1 and TIMP-2 immunoreactivities were expressed in normal corneas, predominantly in the corneal epithelium. After injury, immunoreactivities of both MMPs and TIMPs were increased, notably in the healing corneal epithelium, infiltrating inflammatory cells, stromal fibroblasts and ingrowing vascular endothelial cells. The increase in gross MMP-2 enzymatic activity paralleled the maximal vascular ingrowth on day 4, while the gross MMP-9 enzymatic activity rose immediately on day 1, then decreased steadily, which paralleled the magnitude of inflammatory cell infiltration. The immunoreactivity of MMPs/TIMPs decreased significantly 2 weeks after cauterization. On day 35, MMP-2, TIMP-1 and TIMP-2 staining was seen only in corneal epithelium and vascular endothelial cells. Both the RT-PCR and reverse zymography results revealed a more constant expression of TIMP-2, while the TIMP-1 expression appeared to be more inducible. CONCLUSION: MMPs as well as TIMPs were upregulated in cauterization-induced corneal neovascularization, suggesting that both may participate in extracellular matrix remodeling in the corneal wound healing, inflammation and neovascularization processes.     

Altered expression of matrix metalloproteinases and their tissue inhibitors as possible contributors to corneal droplet formation in climatic droplet keratopathy

Purpose: Climatic droplet keratopathy (CDK) is an acquired corneal disease characterized by progressive scarring of the cornea. In several corneal diseases, matrix metalloproteinases (MMPs) are upregulated during the degradation of epithelial and stromal tissues. We investigated the levels, degree of activation and molecular forms of MMP‐2, MMP‐9, MMP‐8 and MMP‐13 and their tissue inhibitors TIMP‐1 and TIMP‐2 in tear fluid of patients with CDK. Methods: Seventeen CDK patients and 10 controls living in Argentine Patagonia received a complete eye examination, and MMPs and TIMP‐1/2 were determined by immunofluorometric assay (IFMA), gelatin zymography and quantitative Western immunoblot analysis in tear samples. Results: The MMPs were detected mostly in their latent forms. The levels of MMP‐9 and MMP‐2 were found to be significantly elevated in CDK patients, whereas latent and active MMP‐8 levels were significantly enhanced in controls. There was no significant difference in the level of MMP‐13. TIMPs were found as part of complexes, and the TIMP‐1 levels were significantly lower in patients than controls. Conclusion: Elevated MMP‐2 and MMP‐9 levels have been implicated in the failure of corneal re‐epithelialization, and enhanced MMP‐2 and MMP‐9 levels in CDK patients suggest that these MMPs may play a role in corneal scarring in CDK. Elevated levels of MMP‐8 suggest a defensive role for this MMP in inflammatory reactions associated with recurring corneal traumas. Decreased expression of TIMP‐1 in CDK patients suggest deficient antiproteolytic shield likely to render the corneas of CDK patients vulnerable to enhanced MMPs. Overall, these data suggest a mechanistic link between MMPs and TIMP‐1 level in cornea and tears with corneal scarring in CDK.