Baboolal Keshwar, Jones Geraint A, Janezic Alenka, Griffiths David R, Jurewicz Wieslaw A
Welsh Transplant Research Group and Department of Pathology, University Hospital of Wales, Cardiff, Wales, United Kingdom.
Kidney Int. 2002 Feb;61(2):686-96. doi: 10.1046/j.1523-1755.2002.00149.x.
Chronic allograft nephropathy is an important cause of graft failure. Many donor and recipient factors contribute to its development. Prospective analysis of these factors has been hindered by the lack of sensitive and specific indicators of renal injury. As a consequence protocol biopsies have been increasingly used in the assessment of renal allograft injury. We performed protocol renal allograft biopsies to prospectively examine the role of important determinants and mediators of chronic allograft nephropathy.
A total of 51 consecutive cadaveric renal transplant recipients entered a randomized prospective study of tacrolimus (Tac) versus cyclosporine (CsA) microemulsion based immunosuppression. Study patients underwent protocol renal allograft biopsies at the time of engraftment and at 3, 6 and 12 months post-transplantation. Biopsies were analyzed by quantitative polymerase chain reaction (PCR) for mRNA for transforming growth factor-beta (TGF-beta), thrombospondin, and fibronectin. Measurements of renal structural injury were estimated by quantitative assessment of interstitial fibrosis and glomerulosclerosis. Changes in profibrotic growth factors and renal structural injury were related to donor and recipient determinants by stepwise regression analysis.
Longitudinal assessment of renal injury demonstrated an early and progressive increase in mRNA for TGF-beta, thrombospondin (TSP) and fibronectin (FBN): TGF-beta baseline, 1.9 +/- 0.2 log copies; TGF-beta 6 months, 2.5 +/- 0.2 log copies, P < 0.05 6 months vs. baseline; TSP baseline, 1.9 +/- 0.2 log copies; TSP 6 months, 2.4 +/- 0.2 log copies, P < 0.05 6 months vs. baseline; FBN baseline, 2.0 +/- 0.2 log copies; FBN 12 months, 2.3 +/- 0.2 log copies, P < 0.05 12 months vs. baseline. This increase in profibrotic growth factors within the allograft was associated with a significant increase in interstitial fibrosis (Vvi) on renal biopsies: Vvi baseline, 13 +/- 1%; Vvi 3 months, 18 +/- 1%; Vvi 6 months, 28 +/- 2%; Vvi 12 months, 34 +/- 2%; P < 0.05 3, 6, and 12 months vs. baseline. Histological analysis demonstrated chronic allograft nephropathy in 4% biopsies at 3 months, 12% at 6 months and in 49% at 12 months. These changes in renal structure were not associated with any change in creatinine clearance (CCr): CCr 3 months, 56 +/- 2 mL/min, CCr 24 months, 56 +/- 2 mL/min; P=NS. Stepwise regression analysis of key donor and recipient determinants of chronic renal injury identified calcineurin inhibitors and acute rejection episodes as important factors involved in the development of chronic renal injury. In particular, the use of cyclosporine compared to tacrolimus was associated with a tenfold increase in TGF-beta mRNA (TGF-beta mRNA at 6 months, CsA vs. Tac, 3 +/- 0.3 vs. 2 +/- 0.3 log copies, P < 0.05), interstitial fibrosis (Vvi at 6 months, CsA vs. Tac, 33 +/- 4% vs. 24 +/- 2%, P < 0.05). Changes in growth factors and renal structure predicted impaired renal function (CCr at 12 months, CsA vs. Tac, 53 +/- 4 mL/min vs. 62 +/- 2 mL/min, P < 0.05). Similarly, acute rejection episodes were associated with an accelerated development of interstitial fibrosis (Vvi at 6 months, acute rejection vs. no rejection, 34 +/- 3% vs. 25 +/- 2%; P < 0.05), but not with changes in TGF-beta, thrombospondin or fibronectin expression.
Our results suggest that structural injury develops early in the natural history of the renal allograft and is mediated, in part, by the early up-regulation of profibrotic growth factors. We have determined that calcineurin inhibitors, in particular cyclosporine, and acute rejection episodes are key factors in the development of renal structural injury.
慢性移植肾肾病是移植肾失功的重要原因。许多供体和受体因素促成其发展。由于缺乏敏感且特异的肾损伤指标，对这些因素的前瞻性分析受到阻碍。因此，方案活检越来越多地用于评估肾移植损伤。我们进行方案肾移植活检以前瞻性地研究慢性移植肾肾病的重要决定因素和介质的作用。
总共51例连续的尸体肾移植受者进入一项基于他克莫司（Tac）与环孢素（CsA）微乳剂免疫抑制的随机前瞻性研究。研究患者在移植时以及移植后3、6和12个月接受方案肾移植活检。活检通过定量聚合酶链反应（PCR）分析转化生长因子-β（TGF-β）、血小板反应蛋白和纤连蛋白的mRNA。通过对间质纤维化和肾小球硬化的定量评估来估计肾结构损伤的测量值。通过逐步回归分析，将促纤维化生长因子和肾结构损伤的变化与供体和受体决定因素相关联。
肾损伤的纵向评估显示，TGF-β、血小板反应蛋白（TSP）和纤连蛋白（FBN）的mRNA早期且逐渐增加：TGF-β基线，1.9±0.2 log拷贝；TGF-β 6个月，2.5±0.2 log拷贝，6个月与基线相比P<0.05；TSP基线，1.9±0.2 log拷贝；TSP 6个月，2.4±0.2 log拷贝，6个月与基线相比P<0.05；FBN基线，2.0±0.2 log拷贝；FBN 12个月，2.3±0.2 log拷贝，12个月与基线相比P<0.05。移植肾内促纤维化生长因子的这种增加与肾活检中间质纤维化（Vvi）的显著增加相关：Vvi基线，13±1%；Vvi 3个月，18±1%；Vvi 6个月，28±2%；Vvi 12个月，34±2%；3、6和12个月与基线相比P<0.05。组织学分析显示，3个月时4%的活检显示慢性移植肾肾病，6个月时为12%，12个月时为49%。这些肾结构的变化与肌酐清除率（CCr）的任何变化均无关：CCr 3个月，56±2 mL/分钟，CCr 24个月，56±2 mL/分钟；P=无显著性差异。对慢性肾损伤的关键供体和受体决定因素进行逐步回归分析，确定钙调神经磷酸酶抑制剂和急性排斥反应是参与慢性肾损伤发展的重要因素。特别是，与他克莫司相比，使用环孢素与TGF-β mRNA增加十倍相关（6个月时TGF-β mRNA，CsA与Tac相比，3±0.3与2±0.3 log拷贝，P<0.05），间质纤维化（6个月时Vvi，CsA与Tac相比，33±4%与24±2%，P<0.05）。生长因子和肾结构的变化预测肾功能受损（12个月时CCr，CsA与Tac相比，53±4 mL/分钟与62±2 mL/分钟，P<0.05）。同样，急性排斥反应与间质纤维化的加速发展相关（6个月时Vvi，急性排斥与无排斥相比，34±3%与25±2%；P<0.05），但与TGF-β、血小板反应蛋白或纤连蛋白表达的变化无关。
我们的结果表明，结构损伤在肾移植的自然病程早期就已出现，并且部分由促纤维化生长因子的早期上调介导。我们已确定钙调神经磷酸酶抑制剂，尤其是环孢素，以及急性排斥反应是肾结构损伤发展的关键因素。
