The role of tubulointerstitial markers in differential diagnosis and prognosis in patients with type 2 diabetes and biopsy proven diabetic kidney disease.

OBJECTIVE: To evaluate the potential application of tubularinterstitial biomarkers in the differential diagnosis of diabetic kidney disease (DKD) from non-diabetic kidney disease (NDKD), as well as investigate key clinical and pathological parameters to help improve the stratification of patients according to end-stage renal disease risk. METHODS: 132 type 2 diabetic patients with chronic kidney disease were enrolled. Patients were categorized into 2 groups according to the renal biopsy results: DKD (n = 61) and NDKD (n = 71).The independent factors of the occurrence of DKD and the diagnostic implications of tubular biomarkers were explored by logistic regression and receiver-operating characteristic curve analysis. Furthermore, predictors were analyzed by least absolute shrinkage and selection operator regression, and constructed a new model for predicting the unfavorable renal outcomes through Cox proportional hazard regression analysis. RESULTS: Serum neutrophil gelatinase-associated lipocalin (sNGAL) (OR = 1.007; 95%CI = [1.003, 1.012], p = 0.001) was identified as an independent risk factor for the occurrence of DKD in diabetic patients with CKD. Tubular biomarkers including sNGAL, N-acetyl-ß-D-glucosaminidase and ß2 microglobulin (ß2-MG) could complement albuminuria for DKD detection (AUC = 0.926, specificity = 90.14%, sensitivity = 80.33%).Moreover, among of the 47 variables, 4 predictors such as sNGAL, interstitial fibrosis and tubular atrophy (IFTA)score, ß2-MG and estimated glomerular filtration rate were selected to construct a new model for predicting the unfavorable renal outcomes through regression analysis. sNGAL (HR = 1.004; 95%CI = [1.001, 1.007], p = 0.013), IFTA score of 2 (HR = 4.283; 95%CI = [1.086, 16.881], p = 0.038), and IFTA score of 3 (HR = 6.855; 95%CI = [1.766, 26.610], p = 0.005) were considered to be independent risk factors for unfavorable renal outcomes. CONCLUSIONS: Tubulointerstitial injury in DKD is independently associated with renal function decline and routinely detected tubular biomarkers are able to enhance the level of non-invasive diagnosis of DKD beyond traditional factors.

A dynamic nomogram for predicting survival among diabetic patients on maintenance hemodialysis.

INTRODUCTION: Among maintenance hemodialysis (MHD) patients, ones with diabetes mellitus (DM) are known to have the worst outcome. METHODS: A total of 263 MHD patients were included, a dynamic nomogram was established based on multivariable Cox regression analysis. RESULTS: The median overall survival (OS) time was 46 months. The 1-, 3-, and 5-year OS rates were 90.9%, 70.5% and 53.9%, respectively. The multivariable Cox regression analysis indicated that DM duration, cardiovascular complication, baseline values before starting MHD for estimated glomerular filtration rate and serum phosphate were independent risk factors. The C-index of the dynamic nomogram was 0.745 and the calibration curves showed optimal agreement between the model prediction and actual observation for predicting survival probabilities. CONCLUSIONS: Our study was the first to establish dynamic nomogram among diabetic MHD patients, the fast and convenient online tool can be used for individual risk estimation at the point of prognosis prediction.

A new model to predict acute kidney injury after cardiac surgery in patients with renal insufficiency.

OBJECTIVE: To establish a simple model for predicting postoperative acute kidney injury (AKI) requiring renal replacement therapy (RRT) in patients with renal insufficiency (CKD stages 3-4) who underwent cardiac surgery. METHODS: A total of 330 patients were enrolled. Among them, 226 were randomly selected for the development group and the remaining 104 for the validation group. The primary outcome was AKI requiring RRT. A nomogram was constructed based on the multivariate analysis with variables selected by the application of the least absolute shrinkage and selection operator. Meanwhile, the discrimination, calibration, and clinical power of the new model were assessed and compared with those of the Cleveland Clinic score and Simplified Renal Index (SRI) score in the validation group. Results: The rate of RRT in the development group was 10.6% (n = 24), while the rate in the validation group was 14.4% (n = 15). The new model included four variables such as postoperative creatinine, aortic cross-clamping time, emergency, and preoperative cystatin C, with a C-index of 0.851 (95% CI, 0.779-0.924). In the validation group, the areas under the receiver operating characteristic curves for the new model, SRI score, and Cleveland Clinic score were 0.813, 0.791, and 0.786, respectively. Furthermore, the new model demonstrated greater clinical net benefits compared with the Cleveland Clinic score or SRI score. CONCLUSIONS: We developed and validated a powerful predictive model for predicting severe AKI after cardiac surgery in patients with renal insufficiency, which would be helpful to assess the risk for severe AKI requiring RRT.

Analyzing clinical characteristics of patients with different cumulative hemodialysis durations: a cross-sectional study.

BACKGROUND: The objective of this study was to examine the clinical characteristics of patients with different cumulative hemodialysis (HD) durations, so as to improve their survival rate. METHODS: In this cross-sectional study, we extracted background information and relevant clinical data from 145 patients who were undergoing maintenance HD three times a week at the Affiliated Hospital of Nantong University between January 1998 and January 2019. The study subjects were divided into four groups according to the duration of their HD: <5 years, 5-10 years, 10-15 years, and >15 years of HD. We collected the medical history and relevant clinical parameters for each subject, and measured the urea reduction ratio (URR), hemoglobin (Hb), serum calcium, phosphorus, parathyroid hormone (iPTH), and serum albumin (ALB) levels for each group. RESULTS: The average patient age was 52.06 ±  11.93 years old. The average patient age in the 10-15 years and >15 years groups was significantly lower than in the <5 years and 5-10 years groups (P = 0.002, P < 0.001, P = 0.012, and P = 0.0025, respectively). The most common cause of end-stage renal disease (ESRD) was chronic glomerulonephritis. We found no significant differences in URR, Hb, serum calcium, serum phosphorus, iPTH, and ALB levels. CONCLUSION: A prolonged HD duration was related to a younger mean age at the start of HD treatment. The leading cause of ESRD was chronic glomerulonephritis. We predominantly found diabetic nephropathy in the group with a duration of <5 years cumulative HD. Most of the indexes related to hemodialysis almost satisfied the recommended values in these patients.

Anti-Phospholipase A2 Receptor (Anti-PLA2R) Antibody in Diagnosis and Treatment of Idiopathic Membranous Nephropathy: A Single-Center Observational Study in China.

BACKGROUND The aim of this study was to observe the concentration of serum anti-PLA2R antibody in idiopathic membranous nephropathy (IMN) patients and analyze its relationship with clinical and laboratory parameters. MATERIAL AND METHODS We treated 72 patients with idiopathic membranous nephropathy diagnosed by renal biopsy; all these patients who presented nephrotic syndrome were enrolled for investigation, and then underwent combination therapy with prednisone and cyclosporine A for 6 months. We collected data on 24-h total proteinuria (TUpro), creatinine clearance rate (Ccr), and serum albumin (Alb) levels before and after immunosuppressive treatment. Serum anti-PLA2R antibody was measured by enzyme-linked immunosorbent assay (ELISA). RESULTS Fifty-six out of 72 IMN patients presented positive serum anti-PLA2R antibody. The titer of anti-PLA2R antibody was significantly correlated with both TUpro and serum Alb levels of pre- and post-therapeutic values in IMN (P<0.05), but did not have a relationship with Ccr (P>0.05). In comparison with the anti-PLA2R antibody-negative group, there were significantly higher TUpro and lower Alb levels in the anti-PLA2R antibody-positive group (P<0.05). However, Ccr was comparatively lower in the anti-PLA2R antibody-positive group, but the difference was not statistically significant (P>0.05). There were 24 patients with negative anti-PLA2R antibody and 14 patients had complete remission in the positive anti-PLA2R antibody group, while anti-PLA2R antibody of all 14 patients became negative. Eight out of 16 patients without anti-PLA2R antibody went into complete remission. CONCLUSIONS Serum anti-PLA2R antibody, as determined by non-invasive technique, is a specific biomarker for diagnosis of IMN. Our results suggest that serum anti-PLA2R antibody has great potential to guide clinical diagnosis and treatment, as well as prognosis determination, in IMN patients.

[Research update of Klotho in kidney injury and repair].

Klotho is highly expressed in the kidney, while soluble Klotho is detectable in the blood, urine, and cerebrospinal fluid, and has multiple hormone-like functions. The role of Klotho in kidney injury has attracted more and more attentions from researchers. Emerging evidence revealed that the transient deficiency of Klotho is an early event of acute kidney injury (AKI), whereas, in chronic kidney disease, this deficiency is sustained not only in the kidney, but also in other organ systems. Therefore, Klotho could be a potential biomarker for early diagnosis of AKI, as well as for its progression to chronic kidney disease. Moreover, Klotho might have therapeutic value to renal injury. Nevertheless, there are only few studies on the involvement of Klotho in post AKI repair. This review focused on the role of Klotho in not only kidney injury, but also its repair, in particular the relationship between Klotho and cell fate (autophagy/apoptosis/necrosis), repair/regeneration, Wnt/ß-catenin and erythropoietin receptor, one of the Klotho effectors.

Successful pregnancy and delivery in uremic patients with maintenance hemodialysis: A case report.

RATIONALE: It is reported that successful pregnancies in dialyzed uremic women are rare. Over the past years, despite advances in clinical management and technology in dialysis for pregnancy in patients receiving maintenance hemodialysis, uremia remains a high risk factor for adverse outcomes in mother and fetus. PATIENT CONCERNS: In this article, we present a case of pregnancy in a 34-year-old uremic woman on dialysis. After the pregnancy was diagnosed and confirmed, intensive dialysis and multidisciplinary care according to the recommendations in the available literatures were provided. DIAGNOSES: Single pregnancy of 31 GWs (gestational weeks), fetal growth restriction, polyhydramnios, and uremia. OUTCOMES: At 31 weeks' gestation and 4 days, she was admitted to our hospital due to premature rupture of membranes and abdominal pain. Then a female baby weighed 1700 g was delivered successfully. After one year of follow-up, the mother feels well and the baby is healthy. LESSONS: Intensive dialysis, detailed management and multidisciplinary approaches are necessary for optimal outcomes in uremic pregnant mother and fetus.

SB-216763, a GSK-3ß inhibitor, protects against aldosterone-induced cardiac, and renal injury by activating autophagy.

Cardiovascular and renal inflammation induced by Aldosterone (Aldo) plays a pivotal role in the pathogenesis of hypertension and renal fibrosis. GSK-3ß contributes to inflammatory cardiovascular and renal diseases, but its role in Aldo-induced hypertension, and renal damage is not clear. In the present study, rats were treated with Aldo combined with SB-216763 (a GSK-3ß inhibitor) for 4 weeks. Hemodynamic, cardiac, and renal parameters were assayed at the indicated time. Here we found that rats treated with Aldo presented cardiac and renal hypertrophy and dysfunction. Cardiac and renal expression levels of molecular markers attesting inflammation and fibrosis were increased by Aldo infusion, whereas the treatment of SB-216763 reversed these alterations. SB-216763 suppressed cardiac and renal inflammatory cytokines levels (TNF-a, IL-1ß, and MCP-1). Meanwhile, SB-216763 increased the protein levels of LC3-II in the cardiorenal tissues as well as p62 degradation, indicating that SB-216763 induced autophagy activation in cardiac, and renal tissues. Importantly, inhibition of autophagy by 3-MA attenuated the role of SB-216763 in inhibiting perivascular fibrosis, and tubulointerstitial injury. These data suggest that SB-216763 protected against Aldo-induced cardiac and renal injury by activating autophagy, and might be a therapeutic option for salt-sensitive hypertension and renal fibrosis.

Protection of CTGF Antibody Against Diabetic Nephropathy in Mice Via Reducing Glomerular ß-Catenin Expression and Podocyte Epithelial-Mesenchymal Transition.

Despite substantial progress in medical care, the morbidity rate of diabetic nephropathy (DN) remains high in patients with diabetes. Evidence suggests that connective tissue growth factor (CTGF) induced podocyte injury may contribute to DN and CTGF inhibition could reduce albuminuria. However, to date the mechanisms involved in the effect of CTGF on podocyte injury have not been fully understood. The aim of this study is to investigate the effects of therapeutic CTGF antibody on glomerular ß-catenin expression and podocyte epithelial-mesenchymal transition (EMT) in diabetic mice. C57BL/6J mice were randomly divided into three groups as the following: the control, DN, and DN treated by CTGF antibody group. DN was induced by a single intraperitoneal injection of streptozotocin and then CTGF antibody was administrated three times per week for 8 weeks. Urinary albumin excretion, mesangial proliferation and matrix deposition, and ß-catenin expression in glomeruli at mRNA and protein level were all increased in DN mice compared to that in the control. Besides, the development of EMT in podocytes from diabetic mice, demonstrated by the downregulation of nephrin and upregulation of desmin in glomeruli, was detected. Furthermore, blocking CTGF by specific antibody reduced albuminuria, prevented the overexpression of CTGF, as well as ß-catenin, in glomeruli and subsequently ameliorated podocyte EMT in DN mice. In summary, this study suggested that CTGF antibody protected podocytes against injury in DN mice by reducing ß-catenin overexpression and preventing podocyte EMT, which might provide new insight into the mechanism of CTGF inhibition in the treatment of DN. J. Cell. Biochem. 118: 3706-3712, 2017. © 2017 Wiley Periodicals, Inc.

Role of Complement Properdin in Renal Ischemia-Reperfusion Injury.

Renal Ischemia-Reperfusion Injury (IRI) is one of the main causes of Acute Kidney Injury (AKI), and may lead to chronic kidney disease. The high mortality rate of AKI has not changed in the last 5 decades due to non-recognition, nephrotoxin exposure, delayed diagnosis and lack of specific intervention. Complement activation plays important roles in IRI-induced AKI because of its association with immunity, inflammation, cell death and tissue repair. Nevertheless, the role of complement properdin, the sole positive regulator of the alternative pathway, in IRI-induced AKI has not been well defined. This review evaluates the dynamic changes and underlying mechanisms of complement activation with a focus on properdin in both in vitro and in vivo models challenged by hypoxia/ reoxygenation and renal IRI. The multiple actions of properdin associated with HMGB1 and caspase-3, apoptosis and inflammation mediators, are discussed in the context of immunity, injury and repair at both the early and later stages of AKI. The complement activation-independent role of properdin and the effect of modulating properdin with or without genotype alteration are also addressed. Taking together, these might provide new mechanistic insights that potentially benefit timely diagnosis and specific intervention of IRI-induced AKI.

CTGF mediates high-glucose induced epithelial-mesenchymal transition through activation of ß-catenin in podocytes.

OBJECTIVE: It is known that connective tissue growth factor (CTGF) and ß-catenin are involved in DN; however, the underlying molecular mechanisms remain unknown. Here we hypothesized that podocytes undergo epithelial-mesenchymal transition (EMT) in high-glucose condition and CTGF mediates high-glucose induced EMT by activating ß-catenin in podocytes. METHODS: The differentiated podocytes were cultured and divided into three groups: the normal glucose group (5 mmol/L glucose), the high-glucose group (30 mmol/L glucose), and the osmotic control group (5 mmol/L glucose supplemented with 25 mmol/L mannitol). The morphology of cultured podocytes was observed under phase contrast microscopy. To study the relevant markers of EMT, as well as CTGF and ß-catenin, the mRNA and protein expressions were analyzed by real-time PCR and western blotting, respectively. In addition, the effects of inhibition CTGF by anti-CTGF antibody on high-glucose-induced EMT and ß-catenin expression in podocytes were studied. RESULTS: High glucose not only induced phenotypic transition of podocytes but also increased the expression of CTGF and ß-catenin. Under high-glucose condition, podocytes underwent EMT, which were demonstrated by downregulation of nephrin and upregulation of desmin. Moreover, high-glucose-induced EMT and ß-catenin overexpression in podocytes were attenuated by anti-CTGF antibody. CONCLUSION: CTGF and ß-catenin are involved in the EMT of podocytes in diabetes. CTGF mediates high-glucose induced EMT through activation of ß-catenin in podocytes. CTGF inhibition may protect podocytes from EMT in diabetes.

TAK-242, a Toll-Like Receptor 4 Antagonist, Protects against Aldosterone-Induced Cardiac and Renal Injury.

Cardiovascular and renal inflammation induced by Aldosterone (Aldo) plays an important role in the pathogenesis of hypertension and renal fibrosis. Toll-like receptor 4 (TLR4) signaling contributes to inflammatory cardiovascular and renal diseases, but its role in Aldo-induced hypertension and renal damage is not clear. In the current study, rats were treated with Aldo-salt combined with TAK-242 (a TLR4 signaling antagonist) for 4 weeks. Hemodynamic, cardiac and renal parameters were assayed at the indicated time. We found that Aldo-salt-treated rats present cardiac and renal hypertrophy and dysfunction. Cardiac and renal expression levels of TLR4 as well as levels of molecular markers attesting inflammation and fibrosis are increased by Aldo infusion, whereas the treatment of TAK-242 reverses these alterations. TAK-242 suppresses cardiac and renal inflammatory cytokines levels (TNF-a, IL-1ß and MCP-1). Furthermore, TAK-242 inhibits hypertension, cardiac and renal fibrosis, and also attenuates the Aldo-induced Epithelial-Mesenchymal Transition (EMT). In experimental hyperaldosteronism, upregulation of TLR4 is correlated with cardiac and renal fibrosis and dysfunction, and a TLR4 signaling antagonist, TAK-242, can reverse these alterations. TAK-242 may be a therapeutic option for salt-sensitive hypertension and renal fibrosis.

The role of renal damage on cardiac remodeling in patients with diabetic nephropathy.

BACKGROUND: Cardiovascular damage and diabetic nephropathy are major complications in patients with Type 2 diabetic nephropathy (T2DN); however, the role of renal damage on cardiac remodeling is not yet fully known. METHODS: A retrospective research was conducted in 254 T2DN patients. All were divided into three groups according to urinary albumin excretion (UAE): the normoalbuminuria group (UAE < 30 mg/g, n = 18), the microalbuminuria group (UAE 30 - 300 mg/g, n = 99) and the macroalbuminuria group (UAE > 300 mg/g, n = 137). The parameters of cardiac remodeling, left atrial diameter (LAD), left ventricular diameter at the end of diastole (LVDd), interventricular septum (IVS), posterior wall of left ventricle (PWLV) and ejection fraction (EF), were determined by Doppler echocardiography. The effects of renal damage on cardiac remodeling were analyzed. RESULTS: Among the 254 patients, LAD and LVDd enlargement was found in 180 (70.86%) and 53 (20.86%) patients, respectively; 46 cases (18.11%) suffered from both LAD and LVDd enlargement. Compared with normal LAD/LVDd groups, creatinine clearance (Ccr) and hemoglobin (Hb) were significantly lower in the left atrial (LA) and left ventricular (LV) dilated groups. LAD was positively correlated with mesangial sclerosis, tubular-interstitial lesions, interstitial fibrosis, as well as tubular basement membrane thickness (r = 0.273, 0.208, 0.176, 0.155, p < 0.05, respectively). Moreover, in comparison to patients with LA enlargement, more severe renal damage was detected in patients with LV enlargement. CONCLUSION: There is a strong correlation between echocardiographic parameters and kidney lesions in patients with T2DN in China; the more severe the renal damage, the more severe the cardiac structural alteration. Renal damage contributes to cardiac remodeling, which may provide new insights into the pathogenesis of cardiovascular complications ,in diabetes mellitus.

Effects of angiotensin II receptor blocker on myocardial endothelial-to-mesenchymal transition in diabetic rats.

BACKGROUND: Emerging evidence has indicated that the endothelial-to-mesenchymal transition (EndMT) is a crucial event during early stages of cardiac fibrosis. In the present study, we first investigated the influence of Irbesartan (Irb) on myocardial EndMT in diabetic rats. METHODS: Diabetic rats were divided into two groups: the diabetic group (DM) and the Irb-treated group (DM+Irb). Wistar-Kyoto rats served as controls. The pathological changes were investigated by microscopy. Immunofluorescence was performed to evaluate the co-expression of CD31 and fibroblast-specific protein 1 (FSP1). FSP1 and α-SMA expressions were detected by RT-PCR and Western blot analysis. EndMT was also studied in human aortic endothelial cells (HAECs) that had been exposed to high glucose (HG) levels. RESULTS: Increased interstitial fibrosis was detected in the DM group. Double labeling revealed CD31 expression in FSP1-positive cells in the DM group, and this expression was diminished by Irb treatment (P<0.05). In vitro, we found that HG stimulated angiotensin II synthesis in HAECs. When HAECs were exposed to HG, some of the cells acquired a spindle-shaped morphology and demonstrated a loss of CD31 labeling, which was attenuated by Irb treatment. FSP1 and α-SMA mRNA and protein expression levels were markedly upregulated in diabetic rats compared to controls, and their expressions were inhibited by Irb treatment (P<0.05). CONCLUSION: The results provide the novel insight that an angiotensin II receptor blocker might prevent diabetic cardiomyopathy by abrogating EndMT in diabetic rats.

A pilot trial assessing urinary gene expression profiling with an mRNA array for diabetic nephropathy.

BACKGROUND: The initiation and progression of diabetic nephropathy (DN) is complex. Quantification of mRNA expression in urinary sediment has emerged as a novel strategy for studying renal diseases. Considering the numerous molecules involved in DN development, a high-throughput platform with parallel detection of multiple mRNAs is needed. In this study, we constructed a self-assembling mRNA array to analyze urinary mRNAs in DN patients with aims to reveal its potential in searching novel biomarkers. METHODS: mRNA array containing 88 genes were fabricated and its performance was evaluated. A pilot study with 9 subjects including 6 DN patients and 3 normal controls were studied with the array. DN patients were assigned into two groups according to their estimate glomerular rate (eGFR): DNI group (eGFR>60 ml/min/1.73 m(2), n = 3) and DNII group (eGFR<60 ml/min/1.73 m(2), n = 3). Urinary cell pellet was collected from each study participant. Relative abundance of these target mRNAs from urinary pellet was quantified with the array. RESULTS: The array we fabricated displayed high sensitivity and specificity. Moreover, the Cts of Positive PCR Controls in our experiments were 24±0.5 which indicated high repeatability of the array. A total of 29 mRNAs were significantly increased in DN patients compared with controls (p<0.05). Among these genes, α-actinin4, CDH2, ACE, FAT1, synaptopodin, COL4α, twist, NOTCH3 mRNA expression were 15-fold higher than those in normal controls. In contrast, urinary TIMP-1 mRNA was significantly decreased in DN patients (p<0.05). It was shown that CTGF, MCP-1, PAI-1, ACE, CDH1, CDH2 mRNA varied significantly among the 3 study groups, and their mRNA levels increased with DN progression (p<0.05). CONCLUSION: Our pilot study demonstrated that mRNA array might serve as a high-throughput and sensitive tool for detecting mRNA expression in urinary sediment. Thus, this primary study indicated that mRNA array probably could be a useful tool for searching new biomarkers for DN.

Inhibition of integrin-linked kinase by angiotensin II receptor antagonist, irbesartan attenuates podocyte injury in diabetic rats.

BACKGROUND: Integrin-linked kinase (ILK) dysregulation is involved in the progression of diabetic nephropathy (DN). The aim of this study was to investigate the effects of angiotensin II receptor blocker (ARB), irbesartan, on ILK expression and podocyte injury in DN. METHODS: DN was induced by the combined feeding of high-sucrose, high-fat diet and intra-peritoneal injection of low dose of streptozotocin (35 mg/kg) in spontaneously hypertensive rats. Diabetic rats were treated with irbesartan (50 mg×kg(-1)×d(-1)) by gavage for 8 weeks. The renal morphologic changes and podocyte injury were investigated by light and electron microscopy, and the ILK expression was evaluated by real-time RT-PCR and Western blotting analysis. RESULTS: Diabetic rats exhibited with the similar clinical feature of type 2 DN. Morphologically, they were characterized by expansion of mesangial matrix, loss of podocyte and podocyte injury. Impressively, compared to controls, the ILK expression in diabetic rats were upregulated, which were positively correlated with both podocyte injury and albuminuria. Irbesartan significantly prevented ILK overexpression, along with the amelioration of podocyte injury and albuminuria. CONCLUSIONS: ILK plays an important role in mediating podocyte injury in DN; irbesartan inhibits ILK upregulation and attenuates podocyte injury, which might offer a new insight into the role of ARB in preventing DN progression.

The roles of connective tissue growth factor and integrin-linked kinase in high glucose-induced phenotypic alterations of podocytes.

Emerging evidence has suggested that podocytes undergo epithelial-mesenchymal transition (EMT) in diabetic nephropathy (DN). Connective tissue growth factor (CTGF) and integrin-linked kinase (ILK) are involved in the progression of DN. However, the underlying mechanisms of EMT are not well understood. The study aimed to investigate the roles of CTGF and ILK in high glucose-induced phenotypic alterations of podocytes and determine whether ILK signaling is downstream of CTGF. The epithelial marker of nephrin and the mesenchymal marker of desmin were investigated by real-time RT-PCR and Western blotting. The results demonstrated that podocytes displayed a spreading, arborized morphology in normal glucose, whereas they had a cobblestone morphology in high glucose conditions, accompanied by decreased nephrin expression and increased desmin expression, suggesting podocytes underwent EMT. In response to high glucose, CTGF and ILK expression in podocytes were increased in a dose- and time-dependent manner, whereas the increase did not occur in the osmotic control. Furthermore, the inhibition of CTGF with anti-CTGF antibody prevented the phenotypic transition, as demonstrated by the preservation of epithelial morphology, the suppression of high glucose-induced desmin overexpression and the restoration of nephrin. Of note, the upregulation of ILK induced by high glucose was partially blocked by the inhibition of CTGF. In summary, these findings suggested that CTGF and ILK were involved in high glucose-induced phenotypic alterations of podocytes. ILK acted as a downstream kinase of CTGF and high glucose-induced ILK expression might occur through CTGF-dependent and -independent pathways.

Effects of angiotensin receptor blocker on phenotypic alterations of podocytes in early diabetic nephropathy.

BACKGROUND: Emerging evidence suggests that podocyte injury is a crucial event in the stage of diabetic nephropathy (DN), a process in which angiotensin II is implicated. In this study, the authors investigated the influence of irbesartan, an angiotensin receptor blocker, on the phenotypic alterations of podocytes in experimental DN. METHODS: DN was induced by combination of high-sucrose, high-fat diet and intraperitoneal injection of low dose of streptozotocin (35 mg/kg) in spontaneously hypertensive rats. Diabetic rats were treated with irbesartan (50 mg/kg/d) by gavage for 8 weeks. Nondiabetic normotensive Wistar-Kyoto rats, which have the same genetic background as spontaneously hypertensive rat, were used as controls. The renal histological changes were investigated by light and electron microscopy. The epithelial marker of nephrin and mesenchymal marker of desmin were detected by real-time reverse transcriptase-polymerase chain reaction and Western blotting. RESULTS: Compared with controls, diabetic rats were associated with mesangial matrix deposition, thickening of glomerular basement membrane, albuminuria, loss of podocytes and effacement of foot processes. Furthermore, the expression of nephrin was significantly reduced whereas desmin was increased. Irbesartan treatment not only lowered blood pressure and albuminuria but also attenuated podocyte loss, maintenance of nephrin expression and inhibition of desmin expression. CONCLUSIONS: This study demonstrates that early irbesartan intervention attenuates the podocyte damage and ameliorates phenotypic alterations of podocytes, which provides a novel insight for the early application of angiotensin receptor blocker to prevent the development of DN.

Angiotensin II mediates the high-glucose-induced endothelial-to-mesenchymal transition in human aortic endothelial cells.

BACKGROUND: Substantial evidence suggests that high glucose (HG) causes endothelial cell damage; however, the potential mechanism therein has yet to be clarified. The aim of this study was to investigate the influence of HG on the endothelial-to-mesenchymal transition (EndMT) and its relevance to the activation of the renin-angiotensin system. METHODS: Primary human aortic endothelial cells (HAECs) were divided into three groups: a normal glucose (NG) group, HG group, and irbesartan (1 microM)-treated (HG+irbesartan) group. The concentration of angiotensin II in the supernatant was detected by radioimmunoassay. Pathological changes were investigated using fluorescence microscopy and electron microscopy. Immunofluorescence staining was performed to detect the co-expression of CD31 and fibroblast markers, such as fibroblast-specific protein 1 (FSP1). The expressions of FSP1 and alpha-SMA were detected by RT-PCR and Western blot. RESULTS: The treatment of HAECs in the HG group resulted in significant increases in the expressions of FSP1 and angiotensin II in dose-and time-dependent manners. The incubation of HAECs exposure to HG resulted in a fibroblast-like phenotype, wherein increased microfilamentation and a roughened endoplasmic reticulum structure were observed in the cytoplasm. The expressions of FSP1 and alpha-SMA were significantly increased in the HG group, and these changes were inhibited by irbesartan treatment (P < 0.05). Double staining of the HAECs indicated a co-localization of CD31 and FSP1 and that some cells acquired spindle-shaped morphologies and a loss of CD31 staining; however, treatment with irbesartan attenuated the expression of EndMT (P < 0.05). CONCLUSIONS: These findings suggest a novel mechanism in HG-induced endothelial damage via the mediation of the EndMT by angiotensin II, which was inhibited by Irbesartan.