淺沼 克彦

Background. Podocyte damage is considered to be an important factor in the development of glomerulosclerosis. Morphological studies on experimental models of progressive glomerular disease have identified the detachment of podocytes from the glomerular basement membrane (GBM) as a critical step in the development and progression of glomeruloselerosis. Degradation of the GBM by proteinases also might be a potential mechanism of the detachment because the process impairs the connection between podocytes and the GBM. The present study examined the effects of basic fibroblast growth factor (bFGF), transforming growth factor-beta1 (TGF-beta1) and platelet-derived growth factor (PDGF) on the secretion of proteinases [cathepsin L and matrix metalloproteinases (MMPs)] and their inhibitors [cystatin C and tissue inhibitor of metalloproteinase-2 (TIMP-2)] from differentiated podocytes in culture. Methods. Expression of mRNAs for receptors of growth factors (bFGF, PDGF, TGF-beta1), the proteinases and their inhibitors in differentiated podocytes were shown by RT-PCR. The secretion of cathepsin L, cystatin C and TIMP-2 from differentiated podocytes were shown by immunoblot analysis. The activities of MMPs-2 and -9 from differentiated podocytes were shown by gelatin zymography. Results. Expression of mRNAs for receptors of the growth factors, the proteinases and their inhibitors were confirmed. bFGF increased the secretion of cathepsin L (5.04-fold at 20 ng/mL), but did not alter the secretion of its extracellular inhibitor, cystatin C. In contrast, TGF-beta1 increased the activities of MMPs-2 and -9 (3.23-fold at 10 ng/mL and 25.3-fold at 10 ng/mL, respectively) from differentiated podocytes, but did not enhance the secretion of its inhibitor, TIMP-2. In addition, bFGF enhanced the secretion of TIMP-2 (2.75-fold at 20 ng/mL) and TGF-beta1 enhanced the secretion of cystatin C (2.32-fold at 20 ng/mL). These results demonstrate the imbalance of the secretion of proteinases and their inhibitors after incubation of such growth factors. Of particular interest was the observation of differences in regulation of proteinases and their extracellular inhibitors in response to bFGF and TGF-betal. PDGF only slightly increased the secretion of cathepsin L (2.54-fold at 20 ng/mL) but exerted no effect on the secretion of cystatin C, MMPs, and TIMP-2 from differentiated podocytes. Conclusion. These results indicate, to our knowledge for the first time, that in differentiated podocytes, both cathepsin L and its inhibitor are independently regulated by different growth factors. It appears that increases in proteolytic activities may induce degradation of the glomerular basement membrane (GBM), which plays an important role in the progression of glomerulosclerosis.

目的:種々の疾患において,蛋白分解酵素とそれを制御する細胞増殖因子が,細胞外基質の再構築に重要な役割を担っている.今回,細胞増殖因子であるb-FGFによる培養分化糸球体上皮細胞からの蛋白分解酵素とその阻害物質の分泌について検討した.対象:培養分化糸球体上皮細胞が分泌した蛋白分解酵素(カテプシンL)とその阻害物質(シスタチンC)を検討対象とした.方法:イムノブロットにより細胞増殖因子投与時の蛋白分解酵素とその阻害物質の分泌変化を検討した.結果と結論:b-FGFはカテプシンLの分泌を増加させたが,シスタチンCの分泌には影響しなかった.糸球体上皮細胞において,蛋白分解酵素であるカテプシンLは細胞増殖因子であるb-FGFにより制御されていた.糸球体上皮細胞から分泌増加されたカテプシンLは,結果的に糸球体基底膜を分解亢進に導き,糸球体硬化の進展に重要な役割を担っていることが示唆された.

We investigated the relationship between endothelial constitutive nitric oxide synthase (ecNOS) gene polymorphism and lipid metabolism in patients with nondiabetic chronic renal failure on hemodialysis. Serum from 181 nondiabetic patients on hemodialysis were examined. A genomic DNA fragment was amplified by polymerase chain reaction (PCR) for determining the ecNOS genotype, The PCR products were designated as a and b alleles by electrophoresis, In hemodialysis patients, the frequency of the ecNOS4 for b/b, b/a and a/a genotype was 76.6, 22.8 and 0.6%, respectively. There was not significant difference in the levels of total cholesterol (TC), triglyceride (TG) and calculated low-density lipoprotein cholesterol (LDL-c) in sera between patients (aa and ba) with the a allele and patients (bb) without the a allele, On the other hand, the levels of serum high-density lipoprotein cholesterol (HDL-c) in patients with the a allele (51.9 +/- 3.33 mg/dl) were significantly higher than those in patients without the a allele (43.05 +/- 1.40 mg/dl) (p = 0.005). The frequency of patients with the a allele and low levels of serum HDL-c among patients with a long duration of dialysis (greater than or equal to 10 years) was significantly lower than that in patients with short duration of dialysis (<10 years) (p = 0.05), It appears that an intron 4 gene polymorphism in ecNOS may modulate lipid metabolism in nondiabetic patients on hemodialysis and the a allele of ecNOS gene polymorphism may affect the prognosis of hemodialysis patients with low levels of serum HDL-c, Copyright (C) 2001 S. Karger AG, Basel.