【作者】 夏鹏；

【导师】 李学旺； 陈丽萌； 文煜冰；

【作者基本信息】 北京协和医学院 ， 临床医学， 2012， 博士

【摘要】 研究背景：恶性高血压(Malignant Hypertension, MHT)主要表现为严重的高血压(舒张压≥130mmHg),常伴有双侧眼底出血和/或渗出,伴或不伴视乳头水肿；因其起病急,进展快,预后差而受到广泛关注。恶性高血压常累及多个靶器官,其中肾脏受累比例高达63%-90%。有关原发性恶性高血压肾损害临床病理与预后相关性的研究并不多,有限的几项研究,或者病例数较少,或者没有肾脏病理资料,结论也不甚一致。近年来的研究提示肾小管周毛细血管(Peritubular Capillary, PTC)和肾脏病理改变、肾功能恶化程度有较好的相关性,但是目前尚未见在恶性高血压肾损害的病例中报道。在恶性高血压的起病过程中,肾素-血管紧张素-醛固酮系统(Renin-Angiotensin-Aldosterone System, RAAS)的活化有重要作用；肾素是RAAS激活的第一步限速酶,90%由肾脏球旁器分泌,但是具体活化机制研究不多。RAAS的激活和PTC的减少等都可能导致或加重肾脏缺氧,启动缺氧诱导因子(Hypoxia-Inducible Factor, HIF),调节机体对缺氧的适应性反应,但在恶性高血压肾损害中情况不明。本研究回顾性地分析52例病理资料完整的原发性恶性高血压肾损害的临床、病理特点,评价PTC缺失对肾功能和预后的影响,观察肾脏局部肾素表达细胞的特点,了解HIF-1α表达情况,为进一步研究发病机制和潜在的干预措施提供一些线索。研究目的：1.回顾性观察原发性恶性高血压肾损害病人的临床和病理特点,初步分析影响预后的相关因素；2.观察恶性高血压病例肾脏PTC缺失的情况,分析其和临床指标及预后的关联性；3.初步观察恶性高血压病例肾脏局部的肾素和HIF-1α表达特点,观察二者与PTC缺失、临床病理的相关性。研究方法：从2003年1月至2012年3月间在北京协和医院住院的病人中选出52例经肾活检确诊的、临床资料完整的原发性恶性高血压肾损害病例,收集其临床、病理及随访资料；定义长期透析(≥3个月)或死亡为终点事件。对肾小球、肾小管间质及肾脏血管病变进行半定量分析；行CD34(小血管内皮细胞特异性标记)免疫组化染色(n=35),评价PTC缺失程度与对照组(良性肾硬化组17例、肾小球轻微病变组19例)的差异。行肾素和HIF-1α免疫组化染色；对肾组织进行α-SMA和肾素的免疫荧光双染,观察肾脏局部肾素和HIF-1α的表达情况。统计方法：连续变量以均值±标准差的形式表示,计数资料以构成比表示。统计软件为SPSS19.0软件(IBM, USA)。主要统计方法包括t检验、卡方检验、单因素相关分析和COX比例风险模型等。研究结果：1.原发性恶性高血压肾损害病例的临床病理特点52例病人中以男性为主(男/女12：1),平均年龄为34.0±8.2岁(18-52岁),血压最高值为收缩压230.4±25.0mmHg,舒张压156.4±20.6mmHg。血肌酐(Scr)为486.8±375.7μmol/L,24小时尿蛋白定量(24hUpro)为1.87±1.50g/24h,21.1%患者需透析支持。病理提示存在不同程度的肾小球硬化；肾小管萎缩、间质纤维化比例为56±20%；微动脉病变以血管闭塞(24.3%)、内皮粘液样水肿(22.4%)和弹力纤维增生(22.1%)多见。肾小管间质病变与肾小球硬化、微动脉病变比例及微动脉闭塞比例、Scr、24hUpro正相关；微动脉闭塞比例与Scr正相关。出院时病人血肌酐和血压控制率均显著改善(P<0.001)。39例长期随访病例的平均随访时间29.1±30.1个月,肾脏存活和达终点各18例,其中1例死亡,3例失访,1年、3年和5年累积肾脏生存率分别为65%、55%和50%。2.原发性恶性高血压肾损害病例的肾小管周毛细血管损伤PTC面积占皮质比例为2.27±0.74%,显著低于轻微病变组(3.75±0.79%,P<0.001)和良性肾硬化组(2.85±0.51%,P=0.025)。PTC面积比例与血肌酐、是否需透析负相关。COX比例风险模型提示PTC面积减少(RR=13.21,95%CI(1.50,116.69),P=0.020)和CKD分期(RR=4.38,95%CI(1.46,13.15),P=0.008)是肾脏不良结局的独立危险因素。3.原发性恶性高血压肾损害病例的肾素、HIF-1α表达情况原发性恶性高血压病例肾脏局部肾素表达水平显著高于良性肾硬化组和肾小球轻微病变组,但HIF-1α表达强度无显著性差异。胚胎期间表达肾素的血管平滑肌细胞重新分泌肾素的再募集可能是RAAS活化的机制。研究结论：1.原发性恶性高血压患者肾脏受累严重,肾脏缺血性改变突出,现有血管病变的指标与临床相关性欠佳；2.肾脏PTC缺失与临床指标相关性好,且可预测肾脏的长期结局；3.肾脏局部肾素表达强度的升高可能和肾素分泌细胞再募集有关,没有观察到局部HIF-1α的异常表达。更多还原

【Abstract】 BackgroundMalignant hypertension, MHT is a clinical syndrome associated with severely elevated blood pressure and bilateral retinal haemorrhages or exudates, or both, with or without papiloedema. MHT has relatively poor prognosis and usually significant renal involvement. However, only a few clinicopathlogic studies have evaluated the correlations between pathologic lesions and prognosis of essential MHT. Peritubular Capillary, PTC is part of renal microvasculature distributed diffusely in kidney, which is vulnerable to hemodynamic challenge caused by hypertension. Several studies have demonstrated the correlation between PTC loss and renal injury in different disease models but MHT. It has been known for long that Renin-Angiotensin-Aldosterone System, RAAS activation has a pivotal role in the development and progression of MHT. Renin, mostly secreted from the juxtaglomerular apparatus, is the first rate-limiting enzyme in RAAS. However, little is known about the mechanisms of intrarenal renin activation. Both the PTC loss and RAAS activation contribute to the development of renal hypoxia which will lead to the stabilization and activation of Hypoxia-Inducible Factor, HIF, which is thought to be helpful in hypoxic environment. Accumulating evidence suggest that HIF activation might cause renal fibrosis and PTC loss. Therefore, this study retrospectively analyzed the clinical and pathological characteristics of52essential MHT patients confirmed by renal biopsy. The PTC losses, the patterns of renin-secreting cells as well as HIF-la expressions were also evaluated, aiming to provide possible clues for the understanding and management of MHT.Purpose1. Analyze the clinical and pathological characteristics of essential MHT patients, and identify the factors correlated with prognosis preliminarily.2. Evaluate the PTC loss and its associations with clinical manifestations and prognosis in essential MHT patients.3. Observe the patterns of renin secreting cells and its potential recruitment in kidney. Assess the expression of HIF-1α and its possible associations with PTC loss as well as clinical manifestations.MethodThe clinical records and follow-up data of52patients with essential MHT confirmed by renal biopsy in Peking Union Medical College Hospital from January2003to March2012were reviewed. The pathological findings including ischemic glomerular sclerosis, tubulointerstitial injury and arteriolar lesions are evaluated semi-quantitatively. The PTC was evaluated (n=35) by immunohistochemical staining of CD34, a specific marker of arteriolar endothelium and compared with control groups (17patients with benign hypertensive nephrosclerosis, BHN and19patients with glomerular minimal lesions, GML). The immunohistochemical staining of renin and HIF-la were also performed to evaluate the pattern of renin secreting cells and the expression of HIF-la. The renin secreting cell recruitment was assessed by immunofluorescence double-staining of a-SMA and renin. Continuous variables are displayed as mean±standard deviation and compared using student’s t-test, one-way analysis of variance or Pearson’s correlation coefficients. Categorical variables are expressed as percentage and compared with chi-square test. Kaplan-Meier analysis and Cox proportional hazard model were also used. A P-value of<0.05was considered significant. Statistical analysis was performed with the SPSS software (version19.0for Windows).Results1. The clinical and pathological characteristics of52essential MHT patientsThe enrolled patients were mostly male (48M:4F) and relatively young (age34.0±8.2), with the maximum blood pressure of230.4±25.0mmHg over156.4±20.6mmHg. The serum creatinine (Scr) was486.8±375.7μmol/L and the24h urine protein (24hUpro) was1.87±1.50g/24h.21.1%(11/52) of the patients required dialysis. The mean glomerular sclerosis index was2.50±1.39and the mean percentage of tubular atrophy/interstitial fibrosis (TA/IF) were56±20%. Lumen occlusion (24.3%), mucoid changes (22.4%) and intimal hyperplasia (22.1%) were common in arterioles. TA/IF correlated positively with the proportion of arteriolar lesion, lumen occlusion in arterioles and Scr. Lumen occlusion in arterioles correlated positively with Scr, too. After adequate anti-hypertension therapy, the blood pressure and renal function improved significantly (P<0.001). The mean follow-up time of39patients eligible for survival analysis were29.1±30.1months and the renal survival rate at1,3and5year was65%、55%and50%, respectively.2. The PTC loss in primary MHT patientsThe PTC proportion in essential MHT patients was2.27±0.74%, which was significantly less than that of GML patients (3.75±0.79%, P<0.001) and BHN patients (2.85±0.51%, P<0.025). PTC proportion correlated negatively with Scr and the need for dialysis. Cox proportional hazard model identified PTC loss as an independent risk factor for renal outcome (RR=13.21,95%CI (1.50,116.69), P=0.020). 3. The evaluation of Renin and HIF-1α expression in MHT patientsThe renin expression level in essential MHT patients was elevated compared with BHN patients and GML patients. Such elevation in HIF-la expression was not observed. The renin secreting cell recruitment exists in essential MHT patients which might be a potential mechanism for local RAAS activation.Conclusion1. The renal involvement in essential MHT is severe both clinically and pathologically. The correlation of lesions in arterioles and small arteries with renal function and prognosis is not good enough.2. PTC loss in essential MHT patients correlated with renal function well and might predict the long time renal outcome.3. The elevation of renin expression in kidney may be related to renin secreting cell recruitment. Elevation of HIF-1α was not observed.更多还原