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，它是一个主要的事业 视力不佳，经常需要角膜移植。这个 KC的发病率从每10万人中有4人到600人不等，出现了这种疾病 在所有的比赛中。在美国，KC的发病率估计为1 每2000人。通常在很小的时候发病，并可能导致 终生残疾。轻度KC可能在 总体人口比之前认为的更复杂 测量角膜形状的方法现在可以更早地诊断。 最近，人们对KC产生了额外的兴趣，因为一些人认为 患者不适合做屈光手术，因为 被越来越多地表演。而圆锥角膜可能有多个 病因，我们的研究表明，大约75%是 与一种可降解角膜的异常酶系统有关 矩阵。该系统由构成角膜酶的基质组成。 金属蛋白酶-2与自然产生的内源性组织 金属蛋白酶抑制剂，TIMP-1和TIMP-2。 这项拨款的第一个目标是确定基质金属蛋白酶-2和/或 TIMP是这种酶活性升高的原因。以下将是 通过克隆和鉴定：(A)基质金属蛋白酶-2和TIMPs的一级结构 糖测序：(B)基质金属蛋白酶-2和组织基质金属蛋白酶的二级结构 以及(C)降低TIMP-1的机制 通过分析翻译效率和降级来确定KC中的级别 费率。拨款的第二个目标是确定底物(S) 在KC和正常角膜中，基质金属蛋白酶-2作用于角膜，这可能导致 变薄了。我们将对降解碎片进行生化检测 角膜的分离成分(胶原蛋白和 蛋白多糖)和与基质金属蛋白酶-2孵育后的完整角膜。这个 第三个目标是进一步描述最近描述的一种可溶解的 KC细胞产生的抑制基质金属蛋白酶-2转录的因子(S)。这 用柱层析法分离因子及其性质 进一步刻画的。这一可溶的因素对 用Northern方法检测MMP2、TIMP-1和TIMP-2的转录 印迹分析。这些结果将显著提高基本的 正常人对基质金属蛋白酶-2及其抑制物TIMP-1和TIMP-2的认识 人类角膜，也提供了有价值的信息 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.