Hemizygous deletion of CTGF/CCN2 does not suffice to prevent fibrosis of the severely injured kidney
Hemizygous deletion of CTGF/CCN2 does not suffice to prevent fibrosis of the severely injured kidney
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DOI：
10.1016/j.matbio.2012.06.002
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发表时间：
2012-09-01
期刊：
影响因子：
6.9
通讯作者：
Goldschmeding, Roel
中科院分区：
文献类型：
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作者：
Falke, Lucas L.;Dendooven, Amelie;Goldschmeding, Roel
背景：结缔组织生长因子（CTGF/CCN2）是肾纤维化的重要介质。先前的观察表明，CCN2表达的衰减足以减轻早期肾损害。然而，对于CCN2在严重损伤和慢性损伤肾脏纤维化中的作用知之甚少。因此，我们研究了CCN2单倍不全对长期stz诱导的糖尿病肾病、单侧输尿管梗阻（UUO）后梗阻性肾病更晚期以及严重马兜铃酸（AA）诱导的小管毒性肾炎中肾瘢痕进展的影响。方法：以野生型（WT, CCN2(+/+)）和半合子CCN2(+/-) C57BI/6小鼠为研究对象。在糖尿病实验中，注射链脲佐菌素的小鼠和对照组小鼠随访6个月，定期记录血压、血糖和蛋白尿。在UUO实验中，左输尿管梗阻14天，对侧肾脏作为对照。AA实验，小鼠腹腔注射5次AA后，随访25 d，并与对照组小鼠单独注射缓冲液进行比较。采集器官进行组织学、mRNA和蛋白质检测。采用高效液相色谱法测定胶原蛋白含量，以羟脯氨酸/脯氨酸比值表示。结果：与对照组相比，受损肾中CCN2表达明显增加。在所有三种模型中，CCN2（+/-）小鼠损伤肾脏中的CCN2水平平均约为WT损伤肾脏的50%。糖尿病6个月后，WT小鼠尿白蛋白增加2.5倍，而CCN2（+/-）小鼠为1.5倍；肾小球基底膜在WT（+/-）小鼠中扩大5倍，在CCN2（+/-）小鼠中扩大4.4倍；肾小球基底膜在WT（+/-）小鼠中增厚1.3倍，在CCN2（+/-）小鼠中增厚1.5倍（WT与CCN2（+/-）小鼠之间的差异均为NS）。在糖尿病小鼠中，Wt和CCN2（+/-）小鼠的肾小管损伤和间质纤维化评分也没有差异（1.8比1.7），UUO（2.8比2.6）。和AA （1.4 vs. 1.2）模型，这三种模型的巨噬细胞内流和胶原含量也是如此。结论：与轻度和相对早期stz诱导的糖尿病肾病不同，重度和慢性损伤肾脏的瘢痕形成不会因CCN2降低50%至（接近）正常水平而减轻。这表明，要么CCN2在严重和慢性肾脏疾病中是多余的，要么CCN2仅在低于正常浓度时是一个限制因素，需要通过现有或新出现的治疗方法进一步降低，以防止严重损伤肾脏的纤维化。(c) 2012 Elsevier B.V.版权所有
Background: Connective Tissue Growth Factor (CTGF/CCN2) is an important mediator of kidney fibrosis. Previous observations indicated that attenuation of CCN2 expression sufficed to alleviate early kidney damage. However, little is known about the role of CCN2 in fibrosis of severely damaged and more chronically injured kidneys. Therefore, we examined the effects of CCN2 haploinsufficiency on the progression of renal scarring in long-term STZ-induced diabetic nephropathy, in a more advanced stage of obstructive nephropathy following unilateral ureteric obstruction (UUO), and in severe aristolochic acid (AA)-induced tubulotoxic nephritis.Methods: Wild-type (WT, CCN2(+/+)) and hemizygous CCN2(+/-) C57BI/6 mice were studied. In the diabetes experiment, streptozotocin-injected and control mice were followed for 6 months, with regular blood pressure, glycaemia and albuminuria recordings. In the UUO experiment, the left ureter was obstructed for 14 days with the contralateral kidney serving as control. For the AA experiment, mice were followed for 25 days after 5 intraperitoneal injections with AA and compared to control mice injected with buffer alone. Organs were harvested for histology, mRNA and protein measurements. Collagen content was determined by HPLC and expressed as hydroxyproline/proline ratio.Results: CCN2 expression was significantly increased in the damaged as compared to control kidneys. In all three models, CCN2 levels in the damaged kidneys of CCN2(+/-) mice averaged about 50% of those in damaged WT kidneys. After 6 months of diabetes, albuminuria was increased 2.5-fold in WT mice, compared to 1.5-fold in CCN2(+/-) mice, mesangial matrix was expanded 5-fold in WT and 4.4-fold in CCN2(+/-) mice and the glomerular basement membrane was thickened 1.3-fold in WT and 1.5-fold in CCN2(+/-) mice (all differences between WT and CCN2(+/-) mice are NS). Tubular damage and interstitial fibrosis scores were also not different between Wt and CCN2(+/-) mice in the diabetes (1.8 vs. 1.7), UUO (2.8 vs. 2.6). and AA (1.4 vs. 1.2) models, as was the case for macrophage influx and collagen content in these three models.Conclusion: Unlike in mild and relatively early STZ-induced diabetic nephropathy, scarring of severely and chronically damaged kidneys is not attenuated by a 50% reduction of CCN2 to (near) normal levels. This suggests that CCN2 is either redundant in severe and chronic kidney disease, or that it is a limiting factor only at subnormal concentrations requiring further reduction by available or emerging therapies to prevent fibrosis of the severely injured kidney. (c) 2012 Elsevier B.V. All rights reserved.