真武汤对阿霉素所致大鼠肾损伤的治疗作用

 目的：研究真武汤对阿霉素肾病模型（adriamycin nephropathy,AN）大鼠足细胞裂孔隔膜蛋白分子（podocin和nephrin）表达的影响,探讨其防治阿霉素肾病大鼠蛋白尿的机制。方法：采用常规生化、病理方法（包括HE染色、Masson染色及电镜）观察真武汤对AN模型所致纤维化大鼠肾功能、肾组织形态学变化及羟脯氨酸（Hyp）含量的改善作用;采用蛋白免疫印迹等方法探索真武汤对足细胞标志蛋白podocin和nephrin信号分子表达的影响。结果：模型组大鼠尿蛋白（TP）、血尿素氮(BUN)和血清肌酐（SCr）显著增加,肌酐清除率（CCr）显著下降（P<0.05）;Hyp显著增加（P<0.05）;肾组织podocin和nephrin蛋白表达水平显著降低（P<0.05）;肾小管萎缩,基底膜增厚;足突扁平、融合、消失。肾小球集中现象明显;部分肾小管扩张,肾小管上皮细胞变性,蛋白管型明显;肾间质纤维组织增生和较多炎症细胞浸润。与模型组相比,各治疗组TP、BUN和SCr均有一定程度的下降,CCr显著提高;Hyp明显下降（P<0.05）;真武汤组肾组织podocin和nephrin蛋白表达水平显著提高（P<0.05）;肾组织病变程度轻于模型组。结论：真武汤能减少阿霉素肾病大鼠肾组织羟脯氨酸含量,改善肾功能及减轻病理损伤。 真武汤降低模型大鼠蛋白尿的作用可能与其维持足细胞podocin和nephrin的表达有关。     

Co-localization of nephrin,podocin, and the actin cytoskeleton: evidence for a role in podocyte foot process formation

The discovery of the genes for nephrin and podocin, which are mutated in two types of congenital nephrotic syndrome, was pivotal in establishing the podocyte as the central component of the glomerular filtration barrier. In vivo the proteins have been localized to the podocyte slit diaphragm, and there is recent evidence for interaction between the two via the adapter molecule CD2AP. We describe in a human podocyte cell line, the subcellular distribution of nephrin, podocins, and CD2AP and their functional interaction with the cytoskeleton. In addition to membrane expression, nephrin and podocin were detected intracellularly in a filamentous pattern. Double immunolabeling and depolymerization studies showed that nephrin and podocin partially co-localize with actin, most strikingly seen protruding from the tips of actin filaments, and are dependent on intact actin polymers for their intracellular distribution. Treatment of differentiated podocytes with puromycin aminonucleoside, an agent that causes foot process effacement in vivo, disrupted actin and nephrin simultaneously, with loss of cell surface localization. We demonstrate an intimate relationship between nephrin podocin and filamentous actin, and reason that disruption of nephrin/podocin could be a final common pathway leading to foot process effacement in proteinuric diseases.     

Rituximab targets podocytes in recurrent focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a glomerular disease characterized by proteinuria, progression to end-stage renal disease, and recurrence of proteinuria after kidney transplantation in about one-third of patients. It has been suggested that rituximab might treat recurrent FSGS through an unknown mechanism. Rituximab not only recognizes CD20 on B lymphocytes, but might also bind sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b) protein and regulate acid sphingomyelinase (ASMase) activity. We hypothesized that rituximab prevents recurrent FSGS and preserves podocyte SMPDL-3b expression. We studied 41 patients at high risk for recurrent FSGS, 27 of whom were treated with rituximab at time of kidney transplant. SMPDL-3b protein, ASMase activity, and cytoskeleton remodeling were studied in cultured normal human podocytes that had been exposed to patient sera with or without rituximab. Rituximab treatment was associated with lower incidence of posttransplant proteinuria and stabilization of glomerular filtration rate. The number of SMPDL-3b(+) podocytes in postreperfusion biopsies was reduced in patients who developed recurrent FSGS. Rituximab partially prevented SMPDL-3b and ASMase down-regulation that was observed in podocytes treated with the sera of patients with recurrent FSGS. Overexpression of SMPDL-3b or treatment with rituximab was able to prevent disruption of the actin cytoskeleton and podocyte apoptosis induced by patient sera. This effect was diminished in cultured podocytes where SMPDL-3b was silenced. Our study suggests that treatment of high-risk patients with rituximab at time of kidney transplant might prevent recurrent FSGS by modulating podocyte function in an SMPDL-3b-dependent manner.     

Nephrin redistribution on podocytes is a potential mechanism for proteinuria in patients with primary acquired nephrotic syndrome

We investigated the distribution of nephrin by immunofluorescence microscopy in renal biopsies of patients with nephrotic syndrome: 13 with membranous glomerulonephritis (GN), 10 with minimal change GN, and seven with focal segmental glomerulosclerosis. As control, six patients with IgA GN without nephrotic syndrome and 10 normal controls were studied. We found an extensive loss of staining for nephrin and a shift from a podocyte-staining pattern to a granular pattern in patients with nephrotic syndrome, irrespective of the primary disease. In membranous GN, nephrin was co-localized with IgG immune deposits. In the attempt to explain these results, we investigated in vitro whether stimuli acting on the cell cytoskeleton, known to be involved in the pathogenesis of GN, may induce redistribution of nephrin on the surface of human cultured podocytes. Aggregated but not disaggregated human IgG(4), plasmalemmal insertion of membrane attack complex of complement, tumor necrosis factor-alpha, and puromycin, induced the shedding of nephrin with a loss of surface expression. This phenomenon was abrogated by cytochalasin and sodium azide. These results suggest that the activation of cell cytoskeleton may modify surface expression of nephrin allowing a dislocation from plasma membrane to an extracellular site.     

CD2相关蛋白在肾病综合征中的表达及意义

目的观察不同病理类型的原发性肾病综合征(nephrotic syndrome,NS)患者肾小球足细胞中CD2相关蛋白(CD2AP)的表达,探讨其与足细胞损伤的关系。方法选取原发性NS患者54例,10例同期肾肿瘤切除患者正常肾组织作为对照。肾活检后常规染色观察肾脏组织病理改变,肾组织行免疫荧光法CD2AP和肾小球上皮细胞蛋白-1(GLEPP1)双重标记,对肾小球CD2AP的表达进行定位;分别用real time PCR和免疫组化SP法检测组织中CD2AP的表达,采用real time PCR检测nephrin的表达,透射电镜观察足细胞的结构变化,并定量测量足突密度。结果 (1)NS患者肾小球中CD2AP的表达及nephrin的表达下调,足细胞足突不同程度融合,足突密度降低。(2)病理表现为微小病变性肾病(minimal change disease,MCD)、局灶性节段性肾小球硬化(focal segmental glomerulosclerosis,FSGS)和膜性肾病(membranous nephropathy,MN)的NS患者CD2AP表达及nephrin表达较对照组明显降低,且CD2AP与nephrin表达呈正相关,病理表现为MCD和FSGS的NS患者CD2AP表达与足突密度呈正相关。结论本研究首次发现原发性NS患者肾小球足细胞中CD2AP的表达降低,且在MCD和FSGS中与足细胞病变程度相关,提示CD2AP低表达在足细胞病变为主的肾小球疾病中发挥重要作用。CD2AP有利于诊断足细胞病变的早期检测,对CD2AP表达减低进行早期干预可能有助于延缓疾病进展。     

Tumour necrosis factor-α drives Alport glomerulosclerosis in mice by promoting podocyte apoptosis

Chronic renal failure involves the progressive loss of renal parenchymal cells. For example, Alport syndrome develops from mutated type IV collagen that fosters the digestion of glomerular basement membranes and podocyte loss, followed by progressive glomerulosclerosis, ie Alport nephropathy. Here we show that autosomal recessive Alport nephropathy in collagen 4a3-deficient mice is associated with increased intrarenal expression of the pro-apoptotic cytokine tumour necrosis factor-alpha (TNF-α) in glomerular cells including podocytes as well as in infiltrating leukocytes. We therefore hypothesized that TNF-α contributes to Alport glomerulosclerosis by inducing podocyte apoptosis. To address this issue, we treated 4-week-old collagen 4a3-deficient mice with either vehicle or the TNF-α antagonist etanercept for a period of 5 weeks. Etanercept treatment prolonged mean survival from 68 to 81 days as compared to vehicle-treated mice. The beneficial effect of etanercept on survival was associated with a significant improvement of the glomerulosclerosis score, proteinuria, and the glomerular filtration rate at 9 weeks of age. Etanercept treatment specifically reduced the numbers of apoptotic podocytes, increased total podocyte counts, and increased the renal mRNA expression of nephrin and podocin without affecting markers of renal inflammation. TNF-α-induced podocyte loss is a previously unrecognized pathological mechanism of Alport glomerulosclerosis, and TNF-α blockade might be a therapeutic option to delay the progression of Alport nephropathy and potentially of other forms of glomerulosclerosis.     

Mesenchymal Stem Cells Ameliorate Podocyte Injury and Proteinuria in a Type 1 Diabetic Nephropathy Rat Model

Mesenchymal stem cells (MSC) attenuate albuminuria and preserve normal renal histology in diabetic mice. However, the effects of MSC on glomerular podocyte injury remain uncertain. The aim of this study was to evaluate the effects of MSC on podocyte injury in streptozotocin (STZ)-induced diabetic rats. Thirty days after diabetes induction by STZ injection (65 mg/kg, intraperitoneally) in Sprague-Dawley rats, the diabetic rats received medium or 2 × 10⁶ enhanced green fluorescent protein-labeled MSC via the renal artery. In vivo tracking of MSC was followed by immunofluorescence analysis. Diabetes-related physical and biochemical parameters were measured on day 60 after the MSC infusion. The expression of podocyte markers (nephrin and podocin), podocyte survival factors (VEGF and BMP-7), and the ultrastructural pathology of podocytes were also assessed. MSC were only detected in the glomeruli from the left kidney receiving MSC infusion. Compared with medium-treated diabetic rats, rats treated with MSC showed a suppressed increase in kidney weight, kidney to body weight index, creatinine clearance rate, and urinary albumin to creatinine ratio; however, the treatment had no effect on blood glucose or body weight levels. Furthermore, the MSC treatment reduced the loss of podocytes, effacement of foot processes, widening of foot processes, thickening of glomerular basal membrane (GBM), and loss of glomerular nephrin and podocin. Most important, MSC-injected kidneys expressed higher levels of BMP-7 but not of VEGF. Our results clearly demonstrated that intra-arterial administration of MSC prevented the development of albuminuria as well as any damage to or loss of podocytes, though there was no improvement in blood sugar levels. The protective effects of MSC may be mediated in part by increasing BMP-7 secretion.     

阿霉素致足细胞损伤模型的建立

目的：建立一种稳定的小鼠足细胞损伤模型,为进一步研究足细胞的生物特性,以及其相关蛋白与肾性蛋白尿间的关系提供可靠保证。方法应用CCK8检测不同浓度的阿霉素（0．5μg／ml,0．25μg／ml,0．125μg／ml）分别作用24 h,48 h后,足细胞的抑制率;应用流式细胞术检测测定足细胞凋亡情况;应用R?T PCR检测裂孔膜关键因子nephrin, podocin的表达。结果0．25μg／ml的阿霉素作用24 h,抑制率接近50％;流式细胞术及R?T PCR均表明浓度为0．25μg／ml的ADR作用24 h后与正常组存在显著性差异。结论0．25μg／ml的阿霉素作用24 h建立的足细胞模型稳定可靠,可应用于足细胞研究。     

Molecular basis of the functional podocin-nephrin complex: mutations in the NPHS2 gene disrupt nephrin targeting to lipid raft microdomains

Hereditary nephrotic syndrome is a heterogeneous disease, characterizedby heavy proteinuria and renal failure. Mutations of NPHS1 orNPHS2, the genes encoding for nephrin and podocin, lead to earlyonset of heavy proteinuria, and rapid progression to end-stagerenal disease, suggesting that both proteins are essential forthe integrity of the glomerular filter. Podocin is a stomatinprotein family member with a predicted hairpin-like structurelocalizing to the insertion site of the slit diaphragm of podocytes,the visceral glomerular epithelial cells of the kidney. Herewe investigate the pathomechanisms of different disease-causingpodocin mutations. We show that wild-type podocin is targetedto the plasma membrane, and forms homo-oligomers involving thecarboxy and amino terminal cytoplasmic domains. The associationof podocin with specialized lipid raft microdomains of the plasmamembrane was a prerequisite for recruitment of nephrin intorafts. In contrast, disease-causing mutations of podocin (R138Qand R138X) failed to recruit nephrin into rafts either becausethese mutants were retained in the endoplasmic reticulum (R138Q),or because they failed to associate with rafts (R138X) despitetheir presence in the plasma membrane. None of the mutants didaugment nephrin signaling, suggesting that lipid raft targetingfacilitates nephrin signaling. Our findings demonstrate thatthe failure of mutant podocin to recruit nephrin into lipidrafts may be essential for the pathogenesis of NPHS2. ^* To whom correspondence should be addressed. Tel: +49 7612703559;Fax: +49 7612706362; Email: benzing{at}med1.ukl.uni-freiburg.de      

Active proteases in nephrotic plasma lead to a podocin‐dependent phosphorylation of VASP in podocytes via protease activated receptor‐1

Focal segmental glomerulosclerosis (FSGS) is associated with glomerular podocyte injury. Podocytes undergo dramatic changes in their actin structure, with little mechanistic insight to date into the human disease. Post‐transplantation recurrence of FSGS is the archetypal form of the disease caused by unknown circulating plasma ‘factors’. There is increasing indication that plasma protease activity could be central to this disease. Using clinical plasma exchange material, collected from patients in relapse and remission stages of disease, the effects of FSGS plasma on human conditionally immortalized podocytes (ciPods) were studied. We show that vasodilator stimulated phosphoprotein (VASP) is phosphorylated in response to relapse plasma from ten consecutively tested patients, and not in response to paired remission plasma or non‐FSGS controls. The phosphorylation signal is absent in human podocytes carrying a pathological podocin mutation. To test for a plasma ligand, inhibition of proteases in relapse plasma leads to the loss of VASP phosphorylation. By the use of siRNA technology, we show that proteases in the plasma signal predominantly via protease activated receptor‐1 (PAR1) to VASP. Mechanistically, FSGS plasma increases podocyte motility, which is dependent on VASP phosphorylation. These data suggest a specific biomarker for disease activity, as well as revealing a novel and highly specific receptor‐mediated signalling pathway to the actin cytoskeleton. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

siRNA沉默WT1对小鼠足细胞Wnt/β-catenin和nephrin表达的影响

 目的:研究小干扰RNA(siRNA) 干扰WT1基因表达的小鼠足细胞Wnt/β-catenin信号通路的变化及其对足细胞活力和nephrin表达的影响。方法:采用RPMI-1640培养基在33 ℃条件下传代培养足细胞,在37 ℃条件下诱导足细胞分化。应用WT1基因的siRNA转染分化成熟的小鼠足细胞,用MTT法测定细胞活力,用实时qRT-PCR和Western blotting技术分别检测mRNA和蛋白的表达。结果:RNA干扰WT1可诱导小鼠足细胞Wnt1 mRNA和蛋白表达上调,p-β-catenin水平降低及足细胞活力下降,伴有足细胞nephrin mRNA和蛋白的表达明显下调。结论: 沉默WT1基因的表达可诱导足细胞活力下降和nephrin表达下调,可能与Wnt/β-catenin信号通路的激活有关。     

Urinary excretion of IGFBP-1 and -3 correlates with disease activity and differentiates focal segmental glomerulosclerosis and minimal change disease

The glomerular microenvironment is influenced by circulating growth factors that are filtered from the blood stream and pass the glomerular filtration barrier. In this study, we wanted to explore the role of IGF-binding proteins (IGFBPs) in two diseases that concern podocytes. We analyzed glomerular expression and urinary excretion of IGFBP-1, -2, and -3 in patients with focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). We found that patients with active FSGS excrete high amounts of podocalyxin positive cells as well as IGFBP-1 and -3. In human podocytes, we can induce mRNA expression of IGFBP-3 in response to TGF-β and in human microvascular endothelial cells expression of IGFBP-1 and -3 in response to TGF-β and Bradykinin. We conclude that the local expression of IGFBPs in podocytes and endothelial cells might contribute to the pathogenesis of glomerular disease and that IGFBP-1 and -3 are potential non-invasive markers of FSGS.     

HSP27/HSPB1 as an adaptive podocyte antiapoptotic protein activated by high glucose and angiotensin II

Apoptosis is a driving force of diabetic end-organ damage, including diabetic nephropathy (DN). However, the mechanisms that modulate diabetes-induced cell death are not fully understood. Heat shock protein 27 (HSP27/HSPB1) is a cell stress protein that regulates apoptosis in extrarenal cells and is expressed by podocytes exposed to toxins causing nephrotic syndrome. We investigated the regulation of HSPB1 expression and its function in podocytes exposed to factors contributing to DN, such as high glucose and angiotensin (Ang) II. HSPB1 expression was assessed in renal biopsies from patients with DN, minimal change disease or focal segmental glomerulosclerosis (FSGS), in a rat model of diabetes induced by streptozotocin (STZ) and in Ang II-infused rats. The regulation of HSPB1 was studied in cultured human podocytes and the function of HSPB1 expressed in response to pathophysiologically relevant stimuli was explored by short interfering RNA knockdown. Total kidney HSPB1 mRNA and protein expression was increased in rats with STZ-induced diabetes and in rats infused with Ang II. Upregulation of HSPB1 protein was confirmed in isolated diabetic glomeruli. Immunohistochemistry showed increased glomerular expression of HSPB1 in both models and localized glomerular HSPB1 to podocytes. HSPB1 protein was increased in glomerular podocytes from patients with DN or FSGS. In cultured human podocytes HSPB1 mRNA and protein expression was upregulated by high glucose concentrations and Ang II. High glucose, but not Ang II, promoted podocyte apoptosis. HSPB1 short interfering RNA (siRNA) targeting increased apoptosis in a high-glucose milieu and sensitized to Ang II or TGFβ1-induced apoptosis by promoting caspase activation. In conclusion, both high glucose and Ang II contribute to HSPB1 upregulation. HSPB1 upregulation allows podocytes to better withstand an adverse high-glucose or Ang II-rich environment, such as can be found in DN.     

Key molecular events in puromycin aminonucleoside nephrosis rats

Nephrin, podocin and alpha-actinin are all involved in proteinuria, but it is unclear which molecular event plays a crucial role during the development of proteinuria. Immunofluorescence staining and real-time quantitative polymerase chain reaction were used to study the glomerular expression of these molecules in puromycin aminonucleoside (PAN) nephrosis. Morphometric methods were applied to evaluate the podocyte foot process (FP) morphology. Two days after PAN injection, nephrin and podocin staining became discontinuous, podocin intensity decreased and FP swelled. Nephrin protein and mRNA decreased at day 5. Both podocin and nephrin intensity decreased dramatically when heavy proteinuria occurred, but nephrin mRNA was regained. When proteinuria disappeared, podocin recovered whereas nephrin did not (P = 0.02); alpha-actinin intensity increased (P = 0.009) and the distribution changed. The podocyte FP volume density correlated negatively with nephrin (r = -0.78, P = 0.0001) and podocin immunofluorescence intensity (r = -0.76, P = 0.0001). We conclude that, before the onset of proteinuria, the first response was the nephrin and podocin distribution change, podocin protein decrease and swollen FP; the podocin quantitative change was earlier than nephrin. Podocin and nephrin distribution and the protein level was associated with proteinuria more closely than their mRNA level. The delayed alpha-actinin induction might be a reparative response.     

Podocyte-associated molecules in puromycin aminonucleoside nephrosis of the rat

Molecules of central functional significance for the glomerular podocytes are rapidly emerging and have been shown to be distinctly involved in diseases with altered glomerular filtration barrier. Here we used the puromycin aminonucleoside (PA) nephrosis model in the rat to study some key proteins associated with the maintenance of the functional glomerular filtration barrier in vivo. The molecules studied included the filtration slit component nephrin, the hairpin-like membrane protein podocin, the basolateral adhesion molecules beta1 integrin and alpha-dystroglycan, and the cytoskeleton-linking intermediary beta-catenin and the actin-associated alpha-actinin-4. The results showed diminished protein levels of podocin and nephrin in the PA-treated group. beta-catenin showed distinct down-regulation at 3 days of induction, and the control level was reached at 10 days. beta1 integrin was markedly up-regulated during induction. alpha-actinin-4 was not changed at the studied time points. The results show distinct differences in the different domains of podocytes during PA-induced proteinuria.     

R168H and V165X mutant podocin might induce different degrees of podocyte injury via different molecular mechanisms

A lot of mutations of podocin, a key protein of podocyte slit diaphragm (SD), have been found both in hereditary and sporadic focal segmental glomeruloscleorosis (FSGS). Nevertheless, the mechanisms of podocyte injury induced by mutant podocins are still unclear. A compound heterozygous podocin mutation was identified in our FSGS patient, leading to a truncated (podocin ^V165X) and a missense mutant protein (podocin ^R168H), respectively. Here, it was explored whether and how both mutant podocins induce podocyte injury in the in vitro cultured podocyte cell line. Our results showed that podocin ^R168H induced more significant podocyte apoptosis and expression changes in more podocyte molecules than podocin ^V165X. Podocyte injury caused by the normal localized podocin^V165X was effectively inhibited by TRPC6 knockdown. The abnormal retention of podocin^R168H in endoplasmic reticulum (ER) resulted in the mis-localizations of other critical SD molecules nephrin, CD2AP and TRPC6, and significantly up-regulated ER stress markers Bip/grp78, p-PERK and caspase-12. These results implicated that podocin ^R168H and podocin ^V165X induced different degrees of podocyte injury, which might be resulted from different molecular mechanisms. Our findings provided some possible clues for further exploring the pharmacological targets to the proteinuria induced by different mutant podocins.     

Expression patterns of podocyte-associated mRNAs in patients with proliferative or non-proliferative glomerulopathies

Aim: It is not clear how the podocyte damage manifests in different glomerulopathies. This study evaluated the podocyte-associated mRNA profiles in renal tissue and urine of patients with proliferative (PGs) or non-proliferative (NPGs) glomerulopathies. Methods: Messenger RNA levels of nephrin, podocin, podocalyxin, synaptopodin, and alpha-actinin-4 were measured in the kidney tissue and urinary cells by real-time polymerase chain reaction. Podocyte-associated mRNAs were correlated with proteinuria and renal function, and the effect of immunosuppressive treatment of PGs and NPGs on urine mRNAs was assessed up to one year of follow up. Results: Podocyte-associated mRNAs were expressed consistently less in kidney tissue from patients with NPGs, and urinary podocyte mRNA levels were significantly higher in the PG group. After six months of immunosuppressive therapy, patients with PGs showed a significant reduction in the expression of podocin, podocalyxin, and alpha-actinin-4 compared with baseline (p<0.001). In the NPG group, alpha-actinin-4 levels decreased (p=0.008), and there was also a trend toward reduced podocalyxin mRNA (p=0.08). Urine podocyte-associated mRNAs correlated with the level of proteinuria at baseline and at six months, and there was a trend toward an inverse correlation between urinary mRNAs and kidney function at one year of follow up. Conclusions: Podocyte-associated mRNAs were inhibited in kidney tissue concomitantly with their increase in urine in these patients with glomerulopathies. Different profiles of mRNA expression were seen, pointing to a higher degree of intra-renal podocytopenia in the NPGs and of podocyturia in the PGs. The immunosuppressive therapy effectively reduced the urinary levels of podocyte-associated mRNAs.     

Sos2抑制NFATc1介导的糖尿病肾病足细胞损伤的机制研究

目的:观察高糖刺激对体外培养的小鼠肾足细胞鸟苷酸交换因子Sos2(Son of Sevenless homolog2)表达的影响,并初步探讨Sos2在高糖诱导足细胞损伤中的作用及其可能的分子机制。方法:通过免疫荧光染色及激光共聚焦显微镜观察Sos2在糖尿病肾病患者足细胞中的表达;体外培养小鼠永生化足细胞,以高糖(30 mmol/L葡萄糖)刺激足细胞48 h,采用RT-PCR、Western blot和免疫荧光检测高糖刺激下足细胞Sos2的mRNA及蛋白表达;采用Western bolt实验、免疫荧光及划痕实验检测Sos2过表达及沉默后podocin的表达、足细胞的活动性及NFATc1的入核情况;并采用RT-PCR检测NFATc1下游目的基因转录情况。结果:Sos2在糖尿病肾病患者的足细胞及高糖刺激体外培养的足细胞中表达显著降低(P 0. 05);沉默Sos2后,足细胞标志蛋白podocin表达显著降低,足细胞活动性增加,NFATc1入核增加,NFATc1下游目的基因转录增加(P 0. 05);与之相反,过表达Sos2组podocin表达显著增高,足细胞的活动性降低,NFATc1的入核减少,NFATc1下游目的基因转录降低(P 0. 05)。结论:Sos2可能通过抑制NFATc1入核而减轻糖尿病肾病足细胞损伤。     

DC‐SIGN expression on podocytes and its role in inflammatory immune response of lupus nephritis

Podocytes, the main target of immune complex, participate actively in the development of glomerular injury as immune cells. Dendritic cell‐specific intercellular adhesion molecule‐3‐grabbing non‐integrin (DC‐SIGN) is an innate immune molecular that has an immune recognition function, and is involved in mediation of cell adhesion and immunoregulation. Here we explored the expression of DC‐SIGN on podocytes and its role in immune and inflammatory responses in lupus nephritis (LN). Expression of DC‐SIGN and immunoglobulin (Ig)G1 was observed in glomeruli of LN patients. DC‐SIGN was co‐expressed with nephrin on podocytes. Accompanied by increased proteinuria of LN mice, DC‐SIGN and IgG1 expressions were observed in the glomeruli from 20 weeks, and the renal function deteriorated up to 24 weeks. Mice with anti‐DC‐SIGN antibody showed reduced proteinuria and remission of renal function. After the podocytes were stimulated by serum of LN mice in vitro, the expression of DC‐SIGN, major histocompatibility complex (MHC) class II and CD80 was up‐regulated, stimulation of T cell proliferation was enhanced and the interferon (IFN)‐γ/interleukin (IL)‐4 ratio increased. However, anti‐DC‐SIGN antibody treatment reversed these events. These results suggested that podocytes in LN can exert DC‐like function through their expression of DC‐SIGN, which may be involved in immune and inflammatory responses of renal tissues. However, blockage of DC‐SIGN can inhibit immune functions of podocytes, which may have preventive and therapeutic effects.