METALLOPROTEINASES IN NORMAL AND KERATOCONUS CORNEAS

圆锥角膜（KC）是一种以角膜变薄为特征的疾病， 严重的不规则散光 在这个国家，这是一个主要的原因， 视力不佳，经常需要角膜移植。 的 KC的发病率从每10万人4到600不等， 在所有种族中。 在美国，KC的发病率估计为1 每2000人。 通常发病发生在早期年龄，并可导致 终生残疾 轻度KC可能在 一般人口比以前认为的更复杂， 测量角膜形状的方法现在允许早期诊断。 最近，人们对KC产生了额外的兴趣，因为有些人认为 患者不适合进行屈光手术， 越来越多地被执行。 虽然圆锥角膜可能有多个 病因学，我们的研究表明，大约75%是 与异常酶系统相关， 矩阵 该系统由组成性角膜酶、基质 金属蛋白酶-2（MMP-2）和天然存在的内源性组织 金属蛋白酶抑制剂TIMP-1和TIMP-2。 这项资助的第一个目标是确定MMP-2和/或MMP-2基因的改变。 TIMP负责这种升高的酶活性。 以下人员 （a）MMP-2和TIMP的一级结构，通过克隆和 测序，（B）通过碳水化合物分析MMP-2和TIMP的二级结构 和电泳分析，以及（c）降低TIMP-1的机制 通过分析翻译效率和降解， rates. 补助金的第二个目标是确定基质 在KC和正常角膜中，MMP-2作用于KC和正常角膜，这可能导致 变薄 我们将用生化方法检测降解碎片 角膜的分离组分（胶原和胶原）的分布图 蛋白聚糖）和完整角膜。 的 第三个目标是进一步表征最近描述的可溶性 KC细胞产生的抑制MMP-2转录的因子。 这 将通过柱层析分离因子，并对其性质进行研究。 进一步特征化。 这种可溶性因子对 MMP-2、TIMP-1和TIMP-2的转录将通过北方免疫印迹法检测。 印迹分析。 这些成果将大大提高基础 了解MMP-2及其抑制剂TIMP-1和TIMP-2，在正常 人类角膜，也提供了有价值的信息的病因学， KC.

Keratoconus (KC) is a disease characterized by corneal thinning and severe irregular astigmatism. In this country, it is a leading cause of visual morbidity and often requires corneal transplantation. The incidence of KC varies from 4 to 600 per 100,000 and the disease appears in all races. In the U.S., the incidence of KC is estimated to be 1 person per 2000. Typically onset occurs at an early age and can lead to a lifetime of disability. Mild KC is probably more prevalent in the general population than previously thought since more sophisticated methods of measuring corneal shape now allow earlier diagnosis. Recently, there is an additional interest in KC since some feel these patients are not suitable candidates for refractive surgeries which are being increasingly performed. While keratoconus may have multiple etiologies, our studies have demonstrated that approximately 75% are associated with an abnormal enzyme system which can degrade the corneal matrix. This system is composed of a constitutive corneal enzyme, matrix metalloproteinase-2 (MMP-2) and naturally occurring endogenous tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2. The first goal of this grant is to identify alterations in MMP-2 and/or TIMPs responsible for this elevated enzyme activity. The following will be determined: (a) primary structures of MMP-2 and TIMPs by cloning and sequencing, (b) secondary structures of MMP-2 and TIMPs by carbohydrate and electrophoretic analyses, and (c) the mechanism for lower TIMP-1 levels in KC by analyzing the translational efficiency and degradation rates. The second goal of the grant is to identify the substrate(s) within KC and normal corneas acted upon by MMP-2 which could lead to thinning. We will examine biochemically the degradation fragment profiles of the isolated components of corneas (collagens and proteoglycans) and intact corneas, after incubation with MMP-2. The third goal is to further characterize a recently described soluble factor(s) produced by KC cells which can depress MMP-2 transcript. This factor will be isolated by column chromatography and its properties further characterized. The effect this soluble factor has upon the transcription of MMP-2, TIMP-1 and TIMP-2 will be examined by Northern blot analyses. These results will significantly enhance the basic understanding of MMP-2 and its inhibitors, TIMP-1 and TIMP-2, in normal human corneas and also provide valuable information on the etiology of KC.