Repair problems in podocytes: wnt, notch, and glomerulosclerosis

Wnt/Ctnnb1 and Notch signaling play key roles in kidney development and epithelial cell specification. Recent reports have suggested that these pathways are reactivated in response to injury and in different disease conditions. Studies using genetically modified animal models showed that sustained activation of Notch and Wnt signaling in podocytes are causally related to albuminuria and glomerulosclerosis development. Here, we discuss the role and regulation of Wnt/Ctnnb1 and Notch signaling in podocytes.     

局灶节段性肾小球硬化患者常见并发症的分析

目的:观察局灶节段性肾小球硬化(FSGS)患者急性肾损伤(AKI)、感染及血栓栓塞的发生率,探讨并发症发生的危险因素。方法:观察70例经临床及肾脏病理确诊的特发性FSGS患者的AKI、感染及血栓栓塞的发生率,分析并发症的临床特征及高危因素。结果:(1)70例特发性FSGS中,34例(48.6%)并发AKI、14例(20.0%)合并感染、11例(15.7%)出现血栓栓塞。(2)AKI以男性多见,其尿蛋白水平较高,血白蛋白水平较低,小管间质损伤更重,小管急性损伤的程度与AKI的分期有关;随访过程中AKI患者完全缓解率及有效率显著低于未合并AKI者。(3)感染以呼吸道感染多见,院内感染占50%;与非感染组相比,感染组患者的尿蛋白水平更高,血白蛋白、球蛋白、IgG水平则较低;随住院时间延长,感染发生率升高,院内感染所占比例增加;Logistic回归分析显示白蛋白低于20g/L和住院时间延长是感染的独立危险因素。(4)血栓栓塞包括颅内静脉窦血栓2例、颈内静脉血栓1例、右肾静脉血栓1例、股静脉血栓2例、腘静脉血栓2例和肺栓塞3例;血栓栓塞患者的循环内皮细胞计数(CECs)、血管性血友病因子(vWF)高于未合并血栓栓塞者,Logistic回归分析显示CECs和血红蛋白水平升高与血栓栓塞独立相关。结论:FSGS患者肾小管损伤、低白蛋白血症和住院时间延长、血管内皮细胞损伤和血液浓缩分别在AKI、感染、血栓栓塞的发生中起重要作用。     

Effect of post-transplant double filtration plasmapheresis on recurrent focal and segmental glomerulosclerosis in renal transplant recipients

In the present study, we reviewed the effect of post-transplant double filtration plasmapheresis (DFPP) on recurrent focal segmental glomerulosclerosis (FSGS) in the transplanted kidney allograft. Sixteen patients with post-transplant recurrent FSGS were enrolled in this study. Out of 16 patients with recurrent FSGS after transplantation, five did not receive DFPP and lost their grafts, while 11 did receive DFPP and four of these patients lost their grafts. Seven patients were able to maintain normal renal function for an average observation period of 57.1 +/- 40.7 months (range 7-125 months). In five patients who had a significant reduction in urinary protein after DFPP, the urinary protein level decreased from 26.60 +/- 23.05 g/day (range 3.34-62.6 g/day) to 2.95 +/- 3.42 g/day (range 0.02-8.64 g/day) and renal function was maintained. The beneficial effects of DFPP on graft outcome were more likely to occur if the patients experienced a marked drop in urinary excretion. Thus, post-transplant DFPP appears to be effective for reducing urinary protein levels and improving long-term graft survival. With the small numbers in this trial, however, none of the findings were statistically significant. We recommend the use of post-transplant DFPP to prevent the progression of recurrent FSGS.     

The use of apheresis in immune renal disorders

Abstract: Rapidly progressive glomerulonephritis (RPGN) is often associated with the presence of auto‐antibodies. Included in this group are the glomerulonephritides associated with anti‐GBM antibody (Goodpasture's syndrome), IgA mesangial deposition (the renal component of Henoch‐Schönlein purpura), lupus erythematosus, cryoglobulinemia and the antineutrophil cytoplasmic antibody (ANCA)‐associated pauci‐immune group. In each of these cases, apheresis may provide a therapeutically useful option. Apheresis has also been found useful in certain types of antibody‐mediated transplant rejection and in lowering the levels of preformed cytotoxic antibodies which may preclude transplantation. Finally, there are renal diseases in which the immune component is less clearly involved with pathogenesis but for which apheresis may offer a clear benefit, such as in the renal failure associated with ‘cast nephropathy’ (multiple myeloma) or the recurrence of FSGS (focal segmental glomerulosclerosis) in transplanted kidneys. It is the purpose of this paper to review the evidence supporting the use of apheresis in immune‐related diseases.     

End-Stage Renal Disease and Mortality Outcomes Across Different Glomerulonephropathies in a Large Diverse US Population

Objective

To compare renal function decline, incident end-stage renal disease (ESRD), and mortality among patients with 5 common glomerular diseases in a large diverse population.

家族性局灶节段肾小球硬化症一家系临床与基因调查

目的:分析一个局灶节段性肾小球硬化症(FSGS)家系的临床特征,并对已知致病基因进行筛查。方法:调查1个中国汉族人FSGS家系,筛查其中78名成员后对可疑成员进行仔细临床检查。采集家系中67名成员的外周血样抽提基因组DNA,采用PCR扩增先证者NPHS2,ACTN4和TRPC6基因的所有外显子,寻找突变的方法对已知的家族性FSGS致病基因进行筛查。结果:该家系共有4代,103名成员,遗传方式为常染色体显性遗传。78名被调查家系成员中有11例患者和3例疑似患者迟发起病,平均发病年龄35.9岁。两例患者经肾活检证实为FSGS,其余患者均有不同程度蛋白尿,部分伴镜下血尿。家系先证者基因组DNA进行PCR逐个外显子扩增测序,未发现NPHS2、ACTN4、TRPC6三个已知的致病基因存在突变,发现SNP7个。结论:本家系是已报道最大的一个中国汉族人FSGS家系,符合常染色体显性遗传迟发起病型,家系内患者间临床表现存在明显差异。已知基因NPHS2、ACTN4、TRPC6不是该家系的致病基因。     

Diabetic nephropathy is markedly enhanced in mice lacking the bradykinin B2 receptor

Type I human diabetics and streptozotocin-induced diabetic mice with higher genetically determined levels of angiotensin-converting enzyme have an increased risk of developing nephropathy. However, previous experiments in mice and computer simulations indicate that modest increases in angiotensin-converting enzyme have minimal effects on blood pressure and angiotensin II levels, although bradykinin decreases significantly, inferring that bradykinin is critical for protecting the kidney in diabetics. Here, we confirm this inference by demonstrating that Akita diabetic mice lacking the bradykinin B2 receptor develop overt albuminuria, excreting the equivalent of >550 mg/day albumin in humans, which contrasts with the microalbuminuria (equivalent to <150 mg/day) seen in their simply diabetic littermates. The overt albuminuria is accompanied by a marked increase in glomerular mesangial sclerosis. The importance of bradykinin demonstrated here bears strongly on how current drugs reduce diabetic nephropathy and suggests that B2 receptor-specific agonists merit consideration in this context.     

Suppression of transforming growth factor beta and vascular endothelial growth factor in diabetic nephropathy in rats by a novel advanced glycation end product inhibitor, OPB-9195

Aims/hypothesis. Advanced glycation end products (AGEs) participate in the pathogenesis of diabetic nephropathy. We reported earlier that OPB-9195, a synthetic thiazolidine derivative and novel inhibitor of advanced glycation, prevented progression of diabetic glomerulosclerosis by lowering serum concentrations of advanced glycation end products and reducing their deposition in the glomeruli. Here, we examined their contribution and that of growth factors, such as transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF), to the progression of diabetic nephropathy. We also investigated the expression of type IV collagen in the kidneys of Otsuka-Long-Evans-Tokushima-Fatty (OLETF) rats, a Type II (non-insulin-dependent) diabetes mellitus model, after treatment with OPB-9195. Methods. Using northern blots and immunohistochemical techniques, we determined the renal expression of TGF-β and type IV collagen mRNAs and proteins in OLETF rats. We also examined OPB-9195's effects on renal expression of VEGF mRNA and protein. Results. Concomitant increases in TGF-β and type IV collagen expression were observed at each point in time in OLETF rats not given OPB-9195. In contrast, OPB-9195 treatment greatly suppressed the renal expression of TGF-β, VEGF and type IV collagen mRNAs and proteins to that seen in non-diabetic rats. Conclusion/interpretation. Since OPB-9195, an AGE-inhibitor, prevented the progression of diabetic nephropathy by blocking type IV collagen production and suppressing overproduction of two growth factors, TGF-β and VEGF, in diabetic rats, this compound warrants further investigation. [Diabetologia (1999) 42: 579–588] Received: 2 October 1998 and in final revised form: 28 December 1998     

Exogenous activated protein C inhibits the progression of diabetic nephropathy

Summary. Background: Activated protein C (APC) can regulate immune and inflammatory responses and apoptosis. Protein C transgenic mice develop less diabetic nephropathy but whether exogenous administration of APC suppresses established diabetic nephropathy is unknown. Objectives: We investigated the therapeutic potential of APC in mice with streptozotocin‐induced diabetic nephropathy. Methods: Diabetes was induced in unilaterally nephrectomized C57/Bl6 mice using intraperitoneal (i.p.) injection of streptozotocin. Four weeks later, the mice were treated with i.p. exogenous APC every other day for 1 month. Results: APC‐treated mice had a significantly improved blood nitrogen urea‐to‐creatinine ratio, urine total protein to creatinine ratio and proteinuria, and had significantly less renal fibrosis as measured by the levels of collagen and hydroxyproline. The renal tissue concentration of monocyte chemoattractant protein‐1 (MCP‐1), vascular endothelial growth factor (VEGF) and the RNA expression of platelet‐derived growth factor (PDGF), transforming growth factor‐β1 and connective tissue growth factor (CTGF) were significantly lower in APC‐treated mice than in untreated animals. The percentage of apoptotic cells was reduced and the expression of podocin, nephrin and WT‐1 in the glomeruli was significantly improved in mice treated with APC compared with untreated mice. The levels of coagulation markers were not affected by APC treatment. Conclusion: Exogenous APC improves renal function and mitigates pathological changes in mice with diabetic nephropathy by suppressing the expression of fibrogenic cytokines, growth factors and apoptosis, suggesting its potential usefulness for the therapy of this disease.