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。 它包括积累 细胞外基质（ECM）在肾小球内。 硬化症可能是 由ECM合成和降解的失调介导。 一个大家族的基质金属蛋白酶以及组织抑制剂 金属蛋白酶抑制剂（TIMPs）在降解过程中发挥作用。 我们的初步体外实验结果表明：1）正常小鼠系膜细胞 培养的上皮细胞分泌72 kD和92 kD明胶酶 (type IV胶原酶）以及TIMP 1; 2）来源于 NOD小鼠和牛生长激素（bGH）转基因小鼠分泌 主要是72 kD明胶酶; 3）bGH系膜细胞缺乏92 kD明胶酶 金属蛋白酶; 4）当细胞在高浓度的 葡萄糖存在92 kd明胶酶的减少。 最近我们 在体内检查肾小球，发现正常小鼠肾小球含有 编码72 kD物质的mRNA。 这种mRNA在转基因小鼠中增加， 对于患有硬皮病的bGH患者。 TIMP 1和TIMP 2 mRNA不可检测 在小鼠肾小球中，这一事实强调了主要的表型变化 发生在体内。 我们发现TIMP 3在小鼠中表达， 糖尿病小鼠肾小球中的表达增加。 在GH小鼠中， 72 KD明胶酶的上调没有型 静脉注射胶原蛋白。 这一发现可能表明， 细胞外基质的合成和降解之间的关系， 肾小球硬化症的形式。 具有重要临床意义的是 事实上，肾小球的表型变化是 稳定，至少在体外。 肾小球系膜（平滑肌）细胞 从非肥胖糖尿病小鼠中分离和克隆， 自身免疫性胰岛素依赖型糖尿病。 我们先前已经 表征这些细胞，并诱导稳定的表型调节， 在出现持续高血糖之后。 我们发现这个矩阵 金属蛋白酶在这些细胞中显著下调， mRNA和蛋白质水平，通过培养基中高血糖的存在。 因此，高血糖症诱导细胞发生显著变化， 表型上受糖尿病状态调节，但不在细胞中 分离自糖尿病前期动物或其它非糖尿病菌株。

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.