PRODUCTION OF METALLOPROTEINASES AND TIMPS BY GLOMERULAR CELLS

肾小球硬化发生在大量的人类肾脏疾病中， 包括糖尿病肾病。它由以下几部分组成 肾小球内的细胞外基质(ECM)。硬化症可能是 通过调节细胞外基质的合成和降解而起作用。 基质金属蛋白酶和组织抑制因子的大家族 金属蛋白酶(TIMPs)在降解过程中起着重要作用。 我们在体外实验中的初步研究表明：1)正常小鼠系膜 培养的上皮细胞分泌72kD和92kD明胶酶 (IV型胶原酶)以及TIMP1；2)系膜细胞来源于 NOD小鼠和转基因牛生长激素(BGH)小鼠 3)BGH系膜细胞缺少92kD 金属蛋白酶；4)在高密度脂蛋白存在下培养细胞 葡萄糖则是92kd明胶酶的减少。最近我们 在活体内检查肾小球发现正常小鼠肾小球含有 编码72kD物种的mRNA。这种mRNA在转基因小鼠中增加 适用于有硬化性皮损的BGH。TIMP 1和2的mRNAs无法识别 在小鼠肾小球中，强调主要表型变化的事实 在活体内发生。我们发现TIMP3在小鼠体内得到了表达 糖尿病小鼠肾小球明显增多。在生长激素小鼠中 72KD明胶酶的上调不如型胶酶显著 IV型胶原蛋白。这一发现可能表明存在一种不平衡 细胞外基质的合成与降解之间的关系 各种类型的肾小球硬化。具有相当临床意义的是 硬化肾小球的表型变化是 至少在体外是稳定的。肾小球系膜(平滑肌)细胞 从非肥胖性糖尿病小鼠中分离、克隆出 自身免疫性胰岛素依赖型糖尿病。我们之前已经 鉴定这些细胞及其诱导的稳定表型调节 出现持续性高血糖后。我们找到了那个矩阵 金属蛋白酶在这些细胞中显著下调，在 信使核糖核酸和蛋白质水平，由高血糖的存在在介质中。 因此，高血糖会导致细胞发生显著变化，而这些细胞 受糖尿病状态的表型调节，但不是在细胞中 分离自糖尿病前期动物或其他非糖尿病菌株。

Glomerulosclerosis occurs in a large number of human kidney diseases, including diabetic nephropathy. It consists of the accumulation of extracellular matrix (ECM) within the glomerulus. Sclerosis may be mediated by dysregulation of both synthesis and degradation of ECM. A large family of matrix metalloproteinases as well as tissue inhibitors of metalloproteinase (TIMPs) play a role in the degradative process. Our preliminary in vitrl work revealed that: 1) normal mouse mesangial and epithelial cells in culture secrete a 72 kD and a 92 kD gelatinase (type IV collagenase) as well as TIMP1; 2) mesangial cells derived from NOD mice and mice transgenic for bovine growth hormone (bGH) secrete mostly the 72 kD gelatinase; 3) bGH mesangial cells lack the 92 kd metalloproteinase; 4) when cells are cultured in the presence of high glucose there is a decrease in the 92kd gelatinase. Recently we examined glomeruli in vivo and found that normal mouse glomeruli contain mRNA coding the 72kD species. This mRNA is increased in mice transgenic for bGH who have sclerotic lesions. TIMP 1 and 2 mRNAs are undectable in mouse glomeruli, a fact which emphasizes the major phenotypic changes that occur in vivo. We found that TIMP3 was expressed in mouse glomeruli and was increased in diabetic mice. In GH mice the upregulation of the 72KD gelatinase is less prominent than that of type IV collagen. This finding may suggest that there is an imbalance between synthesis and degradation of extracellular matrix in certain forms of glomerulosclerosis. Of considerable clinical significance was the fact that the phenotypic changes in the sclerotic glomeruli were stable, at least in vitro. Glomerular mesangial (smooth muscle) cells were isolated and cloned from non-obese diabetic mice, and model of autoimmune insulin-dependent diabetes mellitus. We have previously characterized these cells and the stable phenotypic modulation induced after the appearance of sustained hyperglycemia. We found that matrix metalloproteinases were markedly down regulated in these cells, at the mRNA and protein levels, by the presence of hyperglycemia in the media. Thus, hyperglycemia induces marked changes in cells which have been phenotypically modulated by the diabetic state, but not in cells isolated from pre-diabetic animals or from other non-diabetic strains.