Ahmed Aimun K, El Nahas A Meguid, Johnson Timothy S
Department of Renal Medicine, Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, United Kingdom.
Exp Clin Transplant. 2012 Aug;10(4):332-43. doi: 10.6002/ect.2012.0013.
Chronic allograft nephropathy remains one of the main causes of late graft loss after kidney transplant owing to multifactorial development of kidney scarring. Chronic allograft nephropathy is characterised by an excess accumulation of extracellular matrix. A key system regulating extracellular matrix homeostasis are matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases. This study sought to determine if a change in the matrix metalloproteinases/tissue inhibitors of matrix metalloproteinases system contributes to chronic allograft nephropathy-associated progressive kidney scarring.
Examination of sequential renal biopsies was done at implantation, acute rejection, and subsequent chronic allograft nephropathy. In situ localisation of matrix metalloproteinase activity was assessed with a high-resolution in situ zymography technique using gelatin and collagen 1 substrates. Matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases were localised using immunohistochemistry.
In situ zymography showed over a 50% reduction in matrix metalloproteinase activity against both collagen 1 and gelatin substrates in chronic allograft nephropathy biopsies. A similar loss of matrix metalloproteinase activity was seen in the glomerular and tubulointerstitial compartments. Immunoreactive matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases were observed intracellularly in mesangial and tubular epithelial cells. Matrix metalloproteinases-1, -2, -3, and -9 were significantly reduced in acute rejection and later in chronic allograft nephropathy. However, glomerular matrix metalloproteinases 1 and 9 and tubulointerstitial matrix metalloproteinase-2 were reduced at implantation. Tissue inhibitors of matrix metalloproteinase-2 and -3 were elevated from implantation onwards. We were unable to stain reproducibly for tissue inhibitors of matrix metalloproteinase-1.
Kidney scarring underlying chronic allograft nephropathy is associated with a reduction in matrix metalloproteinases activity that may be due to reduced expression of matrix metalloproteinases -1, -2, -3, and -9, and up-regulation of tissue inhibitors of matrix metalloproteinases -2 and -3. Some of these changes originate from implantation.
由于肾瘢痕形成的多因素发展，慢性移植肾肾病仍然是肾移植后晚期移植肾丢失的主要原因之一。慢性移植肾肾病的特征是细胞外基质过度积聚。调节细胞外基质稳态的一个关键系统是基质金属蛋白酶和基质金属蛋白酶组织抑制剂。本研究旨在确定基质金属蛋白酶/基质金属蛋白酶组织抑制剂系统的变化是否导致与慢性移植肾肾病相关的进行性肾瘢痕形成。
在植入、急性排斥反应及随后的慢性移植肾肾病阶段对连续的肾活检组织进行检查。使用明胶和胶原蛋白1底物，通过高分辨率原位酶谱技术评估基质金属蛋白酶活性的原位定位。采用免疫组织化学方法对基质金属蛋白酶和基质金属蛋白酶组织抑制剂进行定位。
原位酶谱显示，慢性移植肾肾病活检组织中针对胶原蛋白1和明胶底物的基质金属蛋白酶活性降低超过50%。在肾小球和肾小管间质区域也观察到类似的基质金属蛋白酶活性丧失。在系膜细胞和肾小管上皮细胞内观察到免疫反应性基质金属蛋白酶和基质金属蛋白酶组织抑制剂。基质金属蛋白酶-1、-2、-3和-9在急性排斥反应及随后的慢性移植肾肾病阶段显著降低。然而，肾小球中的基质金属蛋白酶1和9以及肾小管间质中的基质金属蛋白酶-2在植入时就已降低。基质金属蛋白酶组织抑制剂-2和-3从植入时起就升高。我们无法对基质金属蛋白酶组织抑制剂-1进行可重复的染色。
慢性移植肾肾病潜在的肾瘢痕形成与基质金属蛋白酶活性降低有关，这可能是由于基质金属蛋白酶-1、-2、-3和-9的表达减少以及基质金属蛋白酶组织抑制剂-2和-3的上调所致。其中一些变化始于植入时。
