Multi-drug resistance-1 gene polymorphisms in nephrotic syndrome: Impact on susceptibility and response to steroids

Background

Role of multidrug resistance-1 (MDR-1) gene polymorphisms has not been clarified in nephrotic syndrome (NS). Additionally, researchers studied several genetic polymorphisms to explain their influence on different patients' responses to steroid; however the data were inconsistent. Therefore, we aimed to investigate the association of MDR-1 gene polymorphisms [C1236T, G2677T/A, C3435T] and haplotypes with susceptibility to childhood nephrotic syndrome, and whether they influence steroid response.

Methods

We detected MDR-1 gene polymorphisms using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) in 138 NS patients and 140 age and sex matched healthy children.

Results

The frequencies of MDR1 G2677T/A GT, GA, TT + AA genotypes or T allele, MDR1 C3435T TT genotype, and T allele genotype frequencies were significantly increased in NS group. While no significant differences were observed in distributions of C1236T genotypes or allele between NS patients and healthy children. Moreover, steroid non-responder NS patients had significantly higher frequencies of MDR1 G2677T/A GT, GA, and TT + AA genotypes than steroid responsive NS patients. We observed also that NS patients with age less than 6 years old had increased frequencies of MDR1 G2677T/A GT, GA, TT + AA genotypes or T allele MDR1 C3435T CT, TT genotypes and T allele. Interestingly the frequency of the TGC haplotype of MDR1 was lower in the initial steroid responders than in non-responders NS patients. On the contrary, there were no any association between the MDR1 haplotypes with NS susceptibility and they did not influence renal pathological findings.

Conclusion

Our data suggested that MDR1 C3435T or G2677T/A gene polymorphisms are risk factors of increased susceptibility, earlier onset of NS, and steroid resistance.     

Transient Receptor Potential Channel 6 (TRPC6) Protects Podocytes during Complement-mediated Glomerular Disease

Gain-of-function mutations in the calcium channel TRPC6 lead to autosomal dominant focal segmental glomerulosclerosis and podocyte expression of TRPC6 is increased in some acquired human glomerular diseases, particularly in membranous nephropathy. These observations led to the hypothesis that TRPC6 overactivation is deleterious to podocytes through pathological calcium signaling, both in genetic and acquired diseases. Here, we show that the effects of TRPC6 on podocyte function are context-dependent. Overexpression of TRPC6 alone did not directly affect podocyte morphology and cytoskeletal structure. Unexpectedly, however, overexpression of TRPC6 protected podocytes from complement-mediated injury, whereas genetic or pharmacological TRPC6 inactivation increased podocyte susceptibility to complement. Mechanistically, this effect was mediated by Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) activation. Podocyte-specific TRPC6 transgenic mice showed stronger CaMKII activation, reduced podocyte foot process effacement and reduced levels of proteinuria during nephrotoxic serum nephritis, whereas TRPC6 null mice exhibited reduced CaMKII activation and higher levels of proteinuria compared with wild type littermates. Human membranous nephropathy biopsy samples showed podocyte staining for active CaMKII, which correlated with the degree of TRPC6 expression. Together, these data suggest a dual and context dependent role of TRPC6 in podocytes where acute activation protects from complement-mediated damage, but chronic overactivation leads to focal segmental glomerulosclerosis.     

鲤鱼汤对阿霉素肾病大鼠肾组织TGF-β1及下游因子表达的影响

本研究探讨鲤鱼汤利尿消肿拮抗肾纤维化保护肾脏的分子机制。阿霉素6.2 mg/kg尾静脉单次注射制备ADRN模型,2 W后干预连续7 W。检测尿、血生化指标,光镜电镜观察肾组织形态变化,免疫组化检测转化生长因子β1(TGF-β1)及下游因子表达。结果发现模型组较对照组12 h尿量(12 h-Uv)减少,血白蛋白(Alb)降低,肾小球硬化指数(GSI)及间质损伤指数(TII)升高,肾组织Smad7表达下调,转化生TGF-β1、成纤维细胞特异性蛋白-1(FSP-1)、I型胶原(Col-I)表达上调;鲤鱼汤组较模型组12 h-Uv增加,血Alb升高,GSI及TII下降,肾组织Smad7表达上调,TGF-β1、FSP-1、Col-Ⅰ表达下调。表明鲤鱼汤的肾保护作用至少部分与其利尿消肿、调节TGF-β1/Smad7信号通路、抑制上皮细胞转分化(EMT)及细胞外基质沉积(ECM)有关。     

MiR‐802 causes nephropathy by suppressing NF‐κB‐repressing factor in obese mice and human

Obesity is associated with significant microvascular complications including renal injuries and may induce end‐stage renal disease. Emerging studies have demonstrated microRNAs (miRNAs) are potential mediators in the pathophysiological process of nephropathy. The present study aimed to investigate the role of miR‐802 in obesity‐related nephropathy and potential molecular mechanisms. Through utilizing obese mouse model and human subjects, we explored the therapeutic benefits and clinical application of miR‐802 in protecting against nephropathy. Renal miR‐802 level was positively correlated with functional parameters, including blood urea nitrogen and creatinine in obese mice. Specific silencing of renal miR‐802 improved high fat diet (HFD)‐induced renal dysfunction, structural disorders and fibrosis. The up‐regulated inflammatory response and infiltrated macrophages were also significantly decreased in miR‐802 inhibitor‐treated obese mice. Mechanistically, miR‐802 directly bond to 3?‐UTR of NF‐κB‐repressing factor (NRF) and suppressed its expression. In clinical study, the circulating miR‐802 level was significantly increased in obese subjects, and positively correlated with plasma creatinine level but negatively correlated with creatinine clearance. Taken together, our findings provided evidence that miR‐802/NRF signalling was an important pathway in mediating obesity‐related nephropathy. It is a possible useful clinical approach of treating miR‐802 inhibitor to combat nephropathy.     

超声对早期糖尿病肾病的诊断价值及肾动脉血流阻力指数与血清hs-CRP、VEGF的关系分析

目的:研究彩色多普勒超声对早期糖尿病肾病的诊断价值及肾动脉血流阻力指数与血清超敏C反应蛋白(hs-CRP)、血管内皮生长因子(VEGF)的关系。方法:选取从2017年2月～2018年2月兰州大学第二医院收治的早期糖尿病肾病患者50例记为病变组,另取同期于该院进行体检的健康人员50例记为对照组。分别对两组人员进行彩色多普勒超声检查,比较肾血流参数。采用酶联免疫吸附法检测两组人员血清hs-CRP、VEGF水平,并作指标间的相关性分析。结果:病变组肾主动脉、肾锥体两侧叶间动脉、肾段动脉的收缩期峰值速度、舒张期最低速度较对照组降低,病变组肾主动脉、肾锥体两侧叶间动脉、肾段动脉的阻力指数较对照组升高(均P0.05)。病变组血清hs-CRP、VEGF水平较对照组升高(均P0.05)。经Pearson相关性分析显示:早期糖尿病肾病患者肾主动脉、肾锥体两侧叶间动脉、肾段动脉的血流阻力指数与血清hs-CRP、VEGF均呈正相关关系(均P0.05)。结论:彩色多普勒超声应用于早期糖尿病肾病的诊断价值较高,且肾动脉血流阻力指数与血清hs-CRP、VEGF密切相关,临床工作中通过联合检测血清hs-CRP、VEGF,从而有助于早期糖尿病肾病的诊断。     

Klotho attenuates diabetic nephropathy in db/db mice and ameliorates high glucose-induced injury of human renal glomerular endothelial cells

Glomerular endothelial cell injury plays an important role in the development and progression of diabetic nephropathy (DN). The expression and function of klotho in glomerular endothelial cells remain unclear. Thus, this study aimed to investigate the expression and the functional role of klotho in DN progression in mice and in high glucose (HG)-induced cell injury of human renal glomerular endothelial cells (HRGECs) and the underlying mechanism. In this study, HRGECs were cultured with media containing HG to induce endothelial cell injury and db/db mice were used as DN model mice. Klotho was overexpressed or knocked down in HRECs to evaluate its role in HG-induced HRGECs injury. klotho-overexpressing adenovirus (rAAV-klotho) was injected into db/db mice via the tail vein to further validate the protective effect of klotho in DN. Decreased klotho expression was observed in DN patients, DN mice, and HG-exposed HRGECs. Furthermore, klotho overexpression significantly abolished the HG-induced HRGECs injury and activation of Wnt/β-catenin pathway and RAAS. In contrast, klotho knockdown exerted the opposite effects. Moreover, klotho attenuated diabetic nephropathy in db/db mice, which was also associated with inhibition of the Wnt/β-catenin pathway and RAAS. In conclusion, klotho attenuates DN in db/db mice and ameliorates HG-induced injury of HRGECs.     

川陈皮素对糖尿病肾病大鼠的治疗作用研究

为观察川陈皮素对糖尿病肾病的治疗作用,本研究选用120只SD大鼠适应性喂养2周后分为正常组(20只)和糖尿病肾病造模组(100只),成功构建糖尿病肾病模型后选取50只,分为模型组,川陈皮素低剂量、中剂量和高剂量组以及阳性药物贝那普利组,每组10只,治疗6周后处死,收集尿液检测24h-尿量和24h-尿蛋白,收集血液检测血糖、胰岛素、血脂、肾功能指标和炎性因子的变化特点,收集肾脏检测肾脏病理学以及肾脏组织中凋亡相关蛋白Bcl-2、Bax、Caspase-3表达水平。结果显示,模型组有明显肾小球增大、部分系膜增生和间质纤维化,相较于模型组,贝那普利组和川陈皮素三个剂量组肾小球病变减轻;与模型组相比,贝那普利组和川陈皮素低、中、高剂量组UCr、24h蛋白尿、BUN、Scr、血糖、TG、TC、IL-1、IL-6和TNF-α明显降低(P<0.05),胰岛素含量明显升高(P<0.05);与模型组相比,贝那普利组和川陈皮素低、中和高剂量组Bax和Caspase-3明显降低(P<0.05),Bcl-2明显升高(P<0.05)。上述研究表明,川陈皮素对糖尿病肾脏损害大鼠肾功能具有明显的保护作用。     

2型糖尿病模型小鼠造模时间的选择

目的:分析不同时期的2型糖尿病小鼠血生化指标及心肌和肾脏的病理变化情况,为选择2型糖尿病模型小鼠造模时间提供依据。方法:32只健康雄性ICR小鼠高脂饲料喂养6周后,腹腔注射链脲佐菌素(STZ,30mg/kg),连续5d,制备糖尿病模型。9d后测空腹血糖(FBG),高于11.1mmol/L视为糖尿病模型。分别于成模后第4、6、8周处死一组小鼠。另取8只雄性ICR小鼠作为对照组,常规饲料喂养,于糖尿病组小鼠成模后第8周处死。分析小鼠生化及病理情况:①心脏、肾脏脏器系数计算;②血清乳酸脱氢酶(LDH)、肌酸激酶(CK)、肌酐(Cr)和尿素氮(BUN)含量测定;③HE染色观察心肌和肾脏组织病变的整体情况;Masson染色观察心肌组织纤维化情况;PAS染色观察肾脏组织病理变化。结果:与对照组小鼠进行比较,第4、6、8周的糖尿病小鼠心脏器系数升高,血清LDH、CK升高,病理组织学见心肌细胞肥大,纤维化;肾脏脏器系数升高,肾功能肌酐(Cr)、尿素氮(BUN)显著升高,病理组织学见肾小球肥大,肾小管基底膜增厚,管腔萎缩。结论:第6周糖尿病小鼠相关生化病理指标改变相对明显且饲养时间相对较短,故2型糖尿病模型小鼠造模后第6周是进行药物干预和病理、生理、生化等研究的最佳时间。