武汉云克隆科技股份有限公司

Abstract: Volume retention in nephrotic syndrome has been linked to activation of the epithelial sodium channel (ENaC) by proteolysis of its γ-subunit following urinary excretion of serine proteases such as plasmin. Here we tested whether pharmacological inhibition of urinary serine protease activity might protect from ENaC activation and volume retention in nephrotic syndrome. Urine from both nephrotic mice (induced by doxorubicin injection) and nephrotic patients exhibited high aprotinin-sensitive serine protease activity. Treatment of nephrotic mice with the serine protease inhibitor aprotinin by means of subcutaneous sustained-release pellets normalized urinary serine protease activity and prevented sodium retention, as did treatment with the ENaC inhibitor amiloride. In the kidney cortex from nephrotic mice, immunofluorescence revealed increased apical γ-ENaC staining, normalized by aprotinin treatment. In Xenopus laevis oocytes heterologously expressing murine ENaC, aprotinin had no direct inhibitory effect on channel activity but prevented proteolytic channel activation. Thus, our study shows that volume retention in experimental nephrotic syndrome is related to proteolytic ENaC activation by proteasuria and can be prevented by treatment with aprotinin. Hence, inhibition of urinary serine protease activity might become a therapeutic approach to treat patients with nephrotic-range proteinuria.

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摘要：肾病综合征的体积潴留与丝氨酸蛋白酶如纤溶酶的尿排泄之后其γ-亚基的蛋白水解活化有关，从而激活上皮钠通道（ENaC）。在这里，我们测试尿液丝氨酸蛋白酶活性的药理学抑制是否可以防止肾病综合征中的ENaC激活和体积潴留。来自肾病小鼠（通过阿霉素注射诱导的）和肾病患者的尿表现出高抑肽酶敏感性丝氨酸蛋白酶活性。用丝氨酸蛋白酶抑制剂抑肽酶通过皮下持续释放小丸治疗肾病小鼠使尿丝氨酸蛋白酶活性标准化并防止钠潴留，正如用ENaC抑制剂阿米洛利治疗一样。在来自肾病小鼠的肾皮质中，免疫荧光显示顶端γ-ENaC染色增加，通过抑肽酶处理标准化。在异源表达鼠ENaC的非洲爪蟾卵母细胞中，抑肽酶对通道活性没有直接的抑制作用，但阻止了蛋白水解通道的激活。因此，我们的研究表明，实验性肾病综合征的体积潴留与蛋白尿的蛋白水解ENaC活化有关，可以通过抑肽酶治疗来预防。因此，抑制尿丝氨酸蛋白酶活性可能成为治疗肾病范围蛋白尿患者的治疗方法。

使用试剂原文信息：Urinary and plasma aprotinin concentrations were determined using an ELISA kit (Cloud-Clone Corp,Wuhan, China).