Singh Lavleen, Singh Geetika, Sharma Alok, Sinha Aditi, Bagga Arvind, Dinda A K
Department of Pathology, AIIMS, New Delhi, India 110029.
Department of Pediatrics, AIIMS, New Delhi, India 110029.
Hum Pathol. 2015 Jan;46(1):34-9. doi: 10.1016/j.humpath.2014.09.003. Epub 2014 Oct 2.
Calcineurin inhibitors (CNIs) are effective immunosuppressive agents for the successful treatment of childhood steroid-resistant nephrotic syndrome (SRNS). Because these patients require long-term treatment, the identification of early markers of CNI-induced nephrotoxicity (CNIN) is imperative. The monitoring of CNI trough levels, serum creatinine, and glomerular filtration rate is not an accurate marker of CNIN. The present study has been undertaken to identify early markers of CNIN in SRNS patients. Twenty-four pediatric SRNS patients were included with paired renal biopsies, before initiation (time zero biopsy) and at least 1 year after CNI therapy (protocol renal biopsy) with standard dosage. Semiquantitative morphologic grading of the histologic features was done for assessing CNIN. Immunohistochemical markers for oxidative stress (nitrotyrosine [NT]), fibrogenic cytokine (transforming growth factor β1 [TGF-β1]), and endothelial injury (endothelial nitric oxide synthase [eNOS]) were evaluated. In addition, ultrastructural study was done to assess mitochondrial injury in endothelial and tubular epithelial cells. The protocol renal biopsies in comparison with time zero biopsies showed significant increase in glomerulosclerosis, juxtaglomerular apparatus hyperplasia, tubular atrophy, interstitial fibrosis, arteriolar hyalinosis, and smooth muscle vacuolization (P < .05 - P < .001). Significantly higher immunoexpression of eNOS (91.6%), NT (71%), and TGF-β1 (87.5%) was noted in posttreatment biopsies. Mean mitochondrial injury grade among post-CNI cases in endothelial cells and proximal tubular cells was 2.28 and 1.4, whereas in pre-CNI, it was 0.28 and 0.27, respectively. We propose that immunohistochemical overexpression of NT, eNOS, and TGF-β1 is an early marker of CNIN. Endothelial and proximal tubular mitochondrial injury may play an important role in the pathogenesis of CNIN.
钙调神经磷酸酶抑制剂（CNIs）是成功治疗儿童激素抵抗型肾病综合征（SRNS）的有效免疫抑制剂。由于这些患者需要长期治疗，因此识别CNI诱导的肾毒性（CNIN）的早期标志物势在必行。监测CNI谷浓度、血清肌酐和肾小球滤过率并非CNIN的准确标志物。本研究旨在识别SRNS患者中CNIN的早期标志物。纳入了24例儿科SRNS患者，在开始使用标准剂量CNI治疗前（零时间活检）和治疗至少1年后（方案肾活检）进行配对肾活检。对组织学特征进行半定量形态学分级以评估CNIN。评估了氧化应激（硝基酪氨酸[NT]）、促纤维化细胞因子（转化生长因子β1[TGF-β1]）和内皮损伤（内皮型一氧化氮合酶[eNOS]）的免疫组化标志物。此外，进行了超微结构研究以评估内皮细胞和肾小管上皮细胞中的线粒体损伤。与零时间活检相比，方案肾活检显示肾小球硬化、肾小球旁器增生、肾小管萎缩、间质纤维化、小动脉玻璃样变性和平滑肌空泡化显著增加（P <.05 - P <.001）。在治疗后的活检中，eNOS（91.6%）、NT（71%）和TGF-β1（87.5%）的免疫表达明显更高。CNI治疗后内皮细胞和近端肾小管细胞中线粒体损伤的平均分级分别为2.28和1.4，而CNI治疗前分别为0.28和0.27。我们认为NT、eNOS和TGF-β1的免疫组化过表达是CNIN的早期标志物。内皮细胞和近端肾小管线粒体损伤可能在CNIN的发病机制中起重要作用。
