血管紧张素Ⅱ1型受体拮抗剂对早期糖尿病肾病患者尿液中足细胞相关蛋白nephrin、自噬基因Beclin-1 mRNA排泄的影响

目的 观察早期糖尿病肾病(diabetic nephropathy, DN)患者尿液中足细胞、足细胞相关蛋白nephrin、自噬基因Beclin-1 mRNA 排泄及氯沙坦对上述指标的影响。方法 入选2018年1月-2021年1月我院确诊的符合标准的早期DN患者48 例,给予氯沙坦50 mg或100 mg口服6个月,观察治疗前后患者尿液中微量白蛋白、足细胞、足细胞相关蛋白nephrin mRNA、自噬基因Beclin-1 mRNA排泄。结果 早期DN患者尿液中微量白蛋白排泄、足细胞及足细胞相关蛋白nephrin、自噬基因Beclin-1 mRNA排泄均较健康人明显增加(P<0.01)。给予氯沙坦治疗6个月后,与治疗前比较,患者尿液中微量白蛋白、足细胞排泄减少(P<0.05),nephrin mRNA排泄呈下降趋势(P<0.05),自噬基因Beclin-1 mRNA排泄较治疗前有一定增加,但差异无统计学意义(P=0.067)。结论 早期DN患者可通过尿液检查证实存在足细胞损伤。血管紧张素Ⅱ1型受体拮抗剂可以减少DN患者尿微量白蛋白排泄,保护足细胞,并可能增强足细胞自噬作用。     

转铁蛋白水平与男性生育及睾丸足细胞功能的关系

目的：探讨转铁蛋白（Tf）水平与男性生育及睾丸足细胞功能的关系。方法收集临床男性不育症患者和正常生育者的精液标本,采用精子质量分析仪进行精子密度及活动率分析,并检测精液 Tf 水平;无菌切取大鼠睾丸,经胶原酶及透明质酸酶消化,分离出纯度较高的足细胞并培养,测定细胞培养液 Tf 水平;Tf 水平测定均采用免疫速率散射比浊法。结果男性不育症患者精液 Tf 水平[（15±5）μmol／L]低于正常生育者[（24．5±6．5）μmol／L,P ＜0．01],而且与精子密度和活动率呈正相关（P ＜0．01）。正常生育组大鼠睾丸足细胞悬液 Tf 水平[（25±8）μmol／L]高于不育组[（15±6）μmol／L,P ＜0．01]。结论精液 Tf 水平的测定可作为反映足细胞功能,评价曲细精管生精功能及精子质量的指标,对男性不育症的诊断、治疗具有重要的价值。     

GIV/Girdin Links Vascular Endothelial Growth Factor Signaling to Akt Survival Signaling in Podocytes Independent of Nephrin

Podocytes are critically involved in the maintenance of the glomerular filtration barrier and are key targets of injury in many glomerular diseases. Chronic injury leads to progressive loss of podocytes, glomerulosclerosis, and renal failure. Thus, it is essential to maintain podocyte survival and avoid apoptosis after acute glomerular injury. In normal glomeruli, podocyte survival is mediated via nephrin-dependent Akt signaling. In several glomerular diseases, nephrin expression decreases and podocyte survival correlates with increased vascular endothelial growth factor (VEGF) signaling. How VEGF signaling contributes to podocyte survival and prevents apoptosis remains unknown. We show here that Gα–interacting, vesicle-associated protein (GIV)/girdin mediates VEGF receptor 2 (VEGFR2) signaling and compensates for nephrin loss. In puromycin aminonucleoside nephrosis (PAN), GIV expression increased, GIV was phosphorylated by VEGFR2, and p-GIV bound and activated Gαi3 and enhanced downstream Akt2, mammalian target of rapamycin complex 1 (mTORC1), and mammalian target of rapamycin complex-2 (mTORC2) signaling. In GIV-depleted podocytes, VEGF-induced Akt activation was abolished, apoptosis was triggered, and cell migration was impaired. These effects were reversed by introducing GIV but not a GIV mutant that cannot activate Gαi3. Our data indicate that after PAN injury, VEGF promotes podocyte survival by triggering assembly of an activated VEGFR2/GIV/Gαi3 signaling complex and enhancing downstream PI3K/Akt survival signaling. Because of its important role in promoting podocyte survival, GIV may represent a novel target for therapeutic intervention in the nephrotic syndrome and other proteinuric diseases.     

Sphingomyelinase-Like Phosphodiesterase 3b Expression Levels Determine Podocyte Injury Phenotypes in Glomerular Disease

Diabetic kidney disease (DKD) is the most common cause of ESRD in the United States. Podocyte injury is an important feature of DKD that is likely to be caused by circulating factors other than glucose. Soluble urokinase plasminogen activator receptor (suPAR) is a circulating factor found to be elevated in the serum of patients with FSGS and causes podocyte αVβ₃ integrin-dependent migration in vitro. Furthermore, αVβ₃ integrin activation occurs in association with decreased podocyte-specific expression of acid sphingomyelinase-like phosphodiesterase 3b (SMPDL3b) in kidney biopsy specimens from patients with FSGS. However, whether suPAR-dependent αVβ₃ integrin activation occurs in diseases other than FSGS and whether there is a direct link between circulating suPAR levels and SMPDL3b expression in podocytes remain to be established. Our data indicate that serum suPAR levels are also elevated in patients with DKD. However, unlike in FSGS, SMPDL3b expression was increased in glomeruli from patients with DKD and DKD sera-treated human podocytes, where it prevented αVβ₃ integrin activation by its interaction with suPAR and led to increased RhoA activity, rendering podocytes more susceptible to apoptosis. In vivo, inhibition of acid sphingomyelinase reduced proteinuria in experimental DKD but not FSGS, indicating that SMPDL3b expression levels determined the podocyte injury phenotype. These observations suggest that SMPDL3b may be an important modulator of podocyte function by shifting suPAR-mediated podocyte injury from a migratory phenotype to an apoptotic phenotype and that it represents a novel therapeutic glomerular disease target.     

EGF Receptor Deletion in Podocytes Attenuates Diabetic Nephropathy

The generation of reactive oxygen species (ROS), particularly superoxide, by damaged or dysfunctional mitochondria has been postulated to be an initiating event in the development of diabetes complications. The glomerulus is a primary site of diabetic injury, and podocyte injury is a classic hallmark of diabetic glomerular lesions. In streptozotocin-induced type 1 diabetes, podocyte-specific EGF receptor (EGFR) knockout mice (EGFR^podKO) and their wild-type (WT) littermates had similar levels of hyperglycemia and polyuria, but EGFR^podKO mice had significantly less albuminuria and less podocyte loss compared with WT diabetic mice. Furthermore, EGFR^podKO diabetic mice had less TGF-β1 expression, Smad2/3 phosphorylation, and glomerular fibronectin deposition. Immunoblotting of isolated glomerular lysates revealed that the upregulation of cleaved caspase 3 and downregulation of Bcl2 in WT diabetic mice were attenuated in EGFR^podKO diabetic mice. Administration of the SOD mimetic mito-tempol or the NADPH oxidase inhibitor apocynin attenuated the upregulation of p-c-Src, p-EGFR, p-ERK1/2, p-Smad2/3, and TGF-β1 expression and prevented the alteration of cleaved caspase 3 and Bcl2 expression in glomeruli of WT diabetic mice. High-glucose treatment of cultured mouse podocytes induced similar alterations in the production of ROS; phosphorylation of c-Src, EGFR, and Smad2/3; and expression of TGF-β1, cleaved caspase 3, and Bcl2. These alterations were inhibited by treatment with mito-tempol or apocynin or by inhibiting EGFR expression or activity. Thus, results of our studies utilizing mice with podocyte-specific EGFR deletion demonstrate that EGFR activation has a major role in activating pathways that mediate podocyte injury and loss in diabetic nephropathy.     

左归降糖益肾方含药血浆对高糖培养小鼠足细胞凋亡及Caspase-12表达的影响

目的 探讨在高糖作用下,体外培养的小鼠足细胞凋亡及内质网应激凋亡因子Caspase-12 mRNA和蛋白表达水平的变化及左归降糖益肾方含药血浆的调控作用.方法 将体外培养的小鼠足细胞随机分为空白组(A组,25 mmol/L葡萄糖,10％空白血浆)、高糖组(B组,200 mmol/L葡萄糖,10％空白血浆)、左归降糖益肾方含药血浆组(C组,200 mmol/L葡萄糖,10％含药血浆),4-苯基丁酸含药血浆组(D组,200 mmol/L葡萄糖,10％含药血浆).培养48 h后,采用免疫荧光细胞化学法、流式细胞术检测足细胞凋亡情况;Western blot法、RT-PCR法分别检测Caspase-12蛋白或mRNA表达水平的变化.结果 与A组比较:在高糖状态下B组足细胞凋亡率、Caspase-12 mRNA和蛋白的表达水平均升高,差异有统计学意义(P＜0.05).与B组比较:C组、D组足细胞凋亡率,Caspase-12 mRNA和蛋白的表达水平均降低,差异均有统计学意义(P＜0.05).与C组比较:D组足细胞凋亡率降低,差异有统计学意义(P＜0.05);但Caspase-12 mRNA和蛋白的表达水平,差异均无统计学意义(P＞0.05).结论 Caspase-12表达上调,是足细胞凋亡的分子机制之一;10％左归降糖益肾方含药血浆可能通过降低Caspase-12的表达水平,从而保护足细胞.     

瞬时受体电位通道蛋白6参与血管紧张素Ⅱ诱导足细胞损伤的信号传导机制

足细胞表达瞬时受体电位通道蛋白6(TRPC6),TRPC家族是一类能通透钙离子的非选择性阳离子通道,近年来,研究发现TRPC6参与了血管紧张素Ⅱ(AngⅡ)诱导足细胞损伤的病理生理过程.本文就TRPC6一般特性及参与AngⅡ诱导足细胞损伤的信号传导机制作一简述.     

Pathophysiologic mechanisms in diabetic kidney disease: A focus on current and future therapeutic targets

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease around the globe and is one of the main complications in patients with type 1 and 2 diabetes. The standard treatment for DKD is drugs controlling hyperglycemia and high blood pressure. Renin angiotensin aldosterone system blockade and sodium glucose cotransporter 2 (SGLT2) inhibition have yielded promising results in DKD, but many diabetic patients on such treatments nevertheless continue to develop DKD, leading to kidney failure and cardiovascular comorbidities. New therapeutic options are urgently required. We review here the promising therapeutic avenues based on insights into the mechanisms of DKD that have recently emerged, including mineralocorticoid receptor antagonists, SGLT2 inhibitors, glucagon-like peptide-1 receptor agonist, endothelin receptor A inhibition, anti-inflammatory agents, autophagy activators and epigenetic remodelling. The involvement of several molecular mechanisms in DKD pathogenesis, together with the genetic and epigenetic variability of this condition, makes it difficult to target this heterogeneous patient population with a single drug. Personalized medicine, taking into account the genetic and mechanistic variability, may therefore improve renal and cardiovascular protection in diabetic patients with DKD.     

Glomerular barrier dysfunction in glomerulosclerosis- resistant Milan rats with experimental diabetes: the role of renal haemodynamics

Rats of the Milan hypertensive strain (MHS) are resistant to both hypertensive and diabetic renal disease. Genetically determined hypertrophy of intrarenal arteries has been suggested as the putative mechanism preventing transmission of systemic hypertension to the glomerular microcirculation or diabetes-induced loss of autoregulation, which lead to glomerular hypertension and consequent podocyte injury and proteinuria. This study aimed to investigate glomerular barrier function and structure in ageing and diabetic MHS rats under basal conditions and after injection of 2.5 g of bovine serum albumin (BSA) causing increased workload and possibly removing haemodynamic protection by inducing renal cortical vasodilatation. Genetically related rats of the Milan normotensive strain (MNS) served as a proteinuric counterpart. No change in renal function or structure was detected in diabetic MHS rats, whereas MNS rats developed diabetic nephropathy superimposed on that occurring spontaneously in this strain. Diabetic, but not non-diabetic, MHS rats showed significantly reduced synaptopodin and nephrin expression, though to a lesser extent than non-diabetic and diabetic MNS rats, together with unchanged podocyte number, density and structure and no proteinuria. Agrin expression was significantly altered in diabetic versus non-diabetic MHS animals, whereas collagen I was expressed only in diabetic MHS rats and collagen IV content did not change significantly between the two groups. Upon BSA injection, proteinuria increased markedly and abundant BSA was detected only in kidneys from diabetic MHS rats. BSA injection was associated with changes in intrarenal arteries suggesting vasodilatation, without any influx of inflammatory cells. These data indicate that while MNS rats show marked changes in the glomerular filtration barrier with either age or diabetes, glomerulosclerosis-resistant MHS rats develop only minor diabetes-induced podocyte (and extracellular matrix) alterations, which are not associated with proteinuria unless they are unmasked by an increased workload or removal of the haemodynamic protection.