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- The Effects of Cyclosporine A on Minimal Change Nephrosis and Focal Segmental Glomerulosclerosis Induced by Administration of Puromycin Aminonucleoside in Rats.
- Sun Hee Sung
- Korean J Pathol. 1996;30(11):981-997.
- 1,883 View
- 19 Download
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Abstract
PDF - Cyclosporine A(CsA) is known as a potent immunosupressive agent, and recently its supressive effects of proteinuria in minimal change nephrotic syndrome, and other glomerular diseases have been demonstrated. But the mechanism of supression of proteinuria is not clear. This study aimed to investigate the mechanism of supression of proteinuria in puromycin aminonucleoside (PAN) induced minimal change nephrosis(MCN), by a single dose of PAN, and focal segmental glomerulosclerosis(FSG) by long term repeated administration of PAN with unilateral nephrectomy in Sprague-Dawley rats, using transmission electron microscopy. We also analysed the effects of CsA on the histopathologic changes such as glomerular sclerosis, and subtypes of infiltrated mononuclear cells in glomeruli and renal interstitium. The results are as follows: Marked proteinuria was developed in MCN and FSG groups. It was significantly reduced by administration of CsA. BUN and creatinine were significantly increased in FSG with the administration of CsA, compared with FSG without CsA. On ultrastructural examination, MCN group showed effacement of foot processes, and microvillous transformation. Occasional focal detatchment of podocytes from the GBM, vacuolar degeneration, and electron dense droplets in the podocytes were also seen. The latter findings were remarkably reduced by CsA. The Above ultrastructural findings, seen in the MCN group, were more severe in the FSG groups. On comparison of ultrastructural fingings of FSG with or without CsA groups, severe vacuolar degeneration, abundant electron dense granules, and focal detatchment of foot processes were more frequently seen in FSG groups and they were significantly reduced by CsA. But irregularity and thickening of GBM were deepend in FSG with CsA group. There were no significant differences of glomerular sclerosis, adhesion to the Bowman's capsules in both the MCN and the FSG groups by administration of CsA. Foamy degeneration of endothelial and mesangial cells, epithelial proliferation, hyalinosis and mononuclear infiltration were significantly reduced by CsA in FSG groups. Microcalcification was commonly seen in CsA administrated groups. The main sutype of infiltrated mononuclear cells in glomeruli and interstitium were monocytes in FSG groups. The proportion of T cells were higher in interstitium by disease progression and it was significantly decreased by CsA. On conclusion the most important ultrastructural changes, regarded as the main mechanism of supression of proteinuria is that the CsA stabilize the podocytes, by preventing vacuolar degeneration and focal detatchment. But CsA does not influence the progression of glomerular sclerosis in PAN induced nephrosis.
- Expression of Transforming Growth Factor-beta1 in Cyclosporine-Induced Nephropathy in Rats.
- Yu Na Kang, Kwan Kyu Park, Mee Yul Hwang, Kun Young Kwon, Sang Sook Lee, Eun Sook Chang, Hyun Chul Kim
- Korean J Pathol. 2000;34(9):642-651.
- 1,805 View
- 17 Download
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Abstract
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- Cyclosporine nephropathy was induced by intraperitoneal injection of cyclosporine 25 mg/kg in Sprague-Dawley rats daily for 1, 4, 8, and 12 weeks to clarify the relationship between cyclosporine nephropathy and the expression of TGF-beta1 with extracellular matrix deposition. On light microscopic examination, the kidneys in the 12 week cyclosporine-treated rats showed focal or striped fibrosis, vacuolization of tubular cells, and injury of endothelial cells. Immunohistochemically, TGF-beta1 protein was strongly expressed in the cyclosporine-treated rat kidneys, especially in the glomerular endothelial cells, interstitial endothelial cells, tubular epithelial cells, and parietal cells in the Bowman's capsule of the glomerulus as well as the periglomerular arterioles. The amount of TGF-beta1 expression was correlated with the morphological change in the cyclosporine-treated rats. Extracellular matrix, such as fibronectin and collagen IV, was also expressed in the endothelial cells of the glomerulus and the interstitium. It can be concluded, therefore that TGF-beta1 protein is probably involved in the early stage of fibrogenesis in cyclosporine nephropathy. It can be postulated that cyclosporine nephropathy results from the accumulation of extracellular matrix associated with the increase of TGF-beta1 transcription. Therefore, these results could be used in reducing fibrosis in cyclosporine nephropathy.
- Kinetics of Cyclosporine uptake on Cultured Human Proximal Tubular Cells.
- Jung Young Lee
- Korean J Pathol. 1990;24(4):430-435.
- 1,830 View
- 20 Download
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Abstract
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- Cyclosporine A (CSA), a lipophilic cyclic undecapeptide, is not accumulated evently in all tissues and has a high affinity to several tissues such as lymphoid organs, liver, and kidneys. From this point of view, it is reasonable to assume that the amount of CSA uptake would be correlated with the extent of cell injury. On the other hand, verapamil, a Ca2+ channel blocker, bas been shown to ameliorate CSA nephrotoxicity. Since proximal tubule is the major site of drug transport and CSA uptake and its interaction with verapamil in isolated human renal proximal tubular cells. The CSA uptake rapidly increased over the first 5 min and then achieved almost steady-state after 10 min at all concentrations (0.5-10 uM). Kinetic analysis yielded that the Km and Vmax values of CSA were 5.6 uM and 86.2 p mol/mg cell protein/min, respectively. And Ca2+ depletion in media enhanced CSA uptake significantly but verapamil reduced it. These results suggest that the Ca2+ channels and CSA transporting sites on cell membrane are closely associated and that Ca2+ and CSA might be taken up competitively by proximal tubular cells.
- Cyclosporine Toxicity on Cultured Human Renal Proximal Tubular Cells.
- Jung Young Lee
- Korean J Pathol. 1990;24(4):423-429.
- 1,874 View
- 30 Download
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Abstract
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- Nephrotoxicity is the most common dose-limiting factor of cyclosporine A (CSA) in clinical usage. But the mechanism of CSA-induced nephrotoxicity still remains unresolved. Many authors insisted that CSA induced renal proximal tubular cell injury is due to the secondary effects following hemodynamic changes or endothelial cell damage, instead of direct toxicity by CSA. To find out that CSA has a direct toxicity to the proximal tubular cells, the author used primary cultures of human proximal tubular cells to eliminate the hemodynamic or endothelial influences that could be produced in in vivo model. In the present study, the viability against CSA was tested by the neutral red assay method with modulation of Ca2+ amount in incubating media and observed electron microscopically. The viability test showed direct toxic effect of CSA on human proximal tubular cells and this was enhanced by Ca2+ depletion in incubating media. Morphologically noted are accumulation of lipid droplets and polyribosomal dispersion, which may be association with inhibition of cellular synthetic activity. These results suggest the toxixity is a direct effect of cyclosporine and that toxic mechanism may be due to inhibition of cellular synthetic activity. And this experiment also showed that primary cultures of human renal proximal tubular cells can be a good in in vivo model for investigating CSA nephrotoxicity.
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