Høj Thomsen Lise, Fog-Tonnesen Morten, Nielsen Fink Lisbeth, Norlin Jenny, de Vinuesa Amaya García, Krarup Hansen Troels, de Heer Emile, Ten Dijke Peter, Rosendahl Alexander
Diabetes Complications Research, Novo Nordisk A/S, Måløv, Denmark.
Nephron. 2017;135(4):291-306. doi: 10.1159/000453337. Epub 2017 Jan 7.
The role of transforming growth factor-β (TGF-β) has recently gained much attention in diabetic nephropathy and kidney fibrosis. In this study, we extend this to an assessment of transcriptional regulation of the entire TGF-β superfamily in kidneys from diabetic vs. healthy mice. In order to study the translation between mouse model and patients, we evaluated the signature of phosphorylated Sma- and Mad-related protein 2 (pSmad2), as molecular marker of TGF-β/activin activity, in the kidneys of streptozotocin (STZ)-treated mice compared to that of type 1 diabetes (T1D) patients.
Patterns of pSmad2 were determined in kidneys from T1D patients with progressed diabetic nephropathy (DN), defined by hyperglycemia, microalbuminuria, and increased levels of serum creatinine. They were compared to changes seen in the STZ-induced DN mouse model. This was studied by immunohistochemistry (IHC) with an antibody specific for pSmad2. Diabetic mice were also characterized by pSmad1/5/8 (IHC), pSmad2/3 (flow cytometry), and TGF-β family members including bone morphogenetic protein (BMP)-like proteins (quantitative real-time polymerase chain reaction [qPCR]).
Renal tubules in DN patients and in STZ mice showed upregulation of pSmad2 concomitant with significantly enlarged distal tubule lumens (p < 0.0001). Renal-derived CD11b+ cells from STZ mice showed elevated pSmad2/3, while endothelial cells had reduced pSmad2/3 levels. No pSmad1/5/8 was observed in the tubule compartment of STZ-treated mice. On total kidney mRNA level, a signature favoring activation of the TGF-β/activin pathway and inhibition of the BMP pathway was demonstrated by qPCR.
Although the pre-clinical DN model lacks the features of fibrosis present in human DN, both species show induction of a local milieu favoring pSmad2 signaling, which may be useful as a disease biomarker in pre-clinical models.
转化生长因子-β（TGF-β）在糖尿病肾病和肾纤维化中的作用近来备受关注。在本研究中，我们将其扩展至对糖尿病小鼠与健康小鼠肾脏中整个TGF-β超家族转录调控的评估。为了研究小鼠模型与患者之间的转化关系，我们评估了磷酸化的Sma和Mad相关蛋白2（pSmad2）的特征，作为TGF-β/激活素活性的分子标志物，在链脲佐菌素（STZ）处理的小鼠肾脏与1型糖尿病（T1D）患者肾脏中进行比较。
在患有进展性糖尿病肾病（DN）的T1D患者肾脏中确定pSmad2模式，进展性糖尿病肾病由高血糖、微量白蛋白尿和血清肌酐水平升高定义。将其与STZ诱导的DN小鼠模型中观察到的变化进行比较。通过使用针对pSmad2的特异性抗体进行免疫组织化学（IHC）研究。糖尿病小鼠还通过pSmad1/5/8（IHC）、pSmad2/3（流式细胞术）以及包括骨形态发生蛋白（BMP）样蛋白在内的TGF-β家族成员（定量实时聚合酶链反应[qPCR]）进行表征。
DN患者和STZ小鼠的肾小管显示pSmad2上调，同时远端肾小管管腔显著增大（p < 0.0001）。来自STZ小鼠的肾源性CD11b +细胞显示pSmad2/3升高，而内皮细胞的pSmad2/3水平降低。在STZ处理的小鼠肾小管区未观察到pSmad1/5/8。在全肾mRNA水平上，qPCR显示有利于TGF-β/激活素途径激活和BMP途径抑制的特征。
尽管临床前DN模型缺乏人类DN中存在的纤维化特征，但两种物种均显示出有利于pSmad2信号传导的局部环境诱导，这在临床前模型中可能作为疾病生物标志物有用。
