Aimin Liu

Myo1e Impairment Results in Actin Reorganization, Podocyte Dysfunction, and Proteinuria in Zebrafish and Cultured Podocytes

Background Podocytes serve as an important constituent of the glomerular filtration barrier. Recently, we and others identified Myo1e as a key molecular component of the podocyte cytoskeleton. Results Myo1e mRNA and protein was expressed in human and mouse kidney sections as determined by Northern blot and reverse transcriptase PCR, and its expression was more evident in podocytes by immunofluorescence. By specific knock-down of MYO1E in zebrafish, the injected larvae exhibited pericardial edema and pronephric cysts, consistent with the appearance of protein in condensed incubation supernate. Furthermore, specific inhibition of Myo1e expression in a conditionally immortalized podocyte cell line induced morphological changes, actin cytoskeleton rearrangement, and dysfunction in cell proliferation, migration, endocytosis, and adhesion with the glomerular basement membrane. Conclusions Our results revealed that Myo1e is a key component contributing to the functional integrity of podocytes. Its impairment may cause actin cytoskeleton re-organization, alteration of cell shape, and membrane transport, and podocyte drop-out from the glomerular basement membrane, which might eventually lead to an impaired glomerular filtration barrier and proteinuria.

Efficacy of triptolide for children with moderately severe Henoch-Schonlein purpura nephritis presenting with nephrotic range proteinuria: a prospective and controlled study in China.

Objective. To observe the clinical efficacy of the Chinese herb, Triptolide, in children with moderately severe Henoch-Schönlein purpura nephritis (HSPN). Methods. From January 2007 to December 2011, 56 HSPN children manifested by nephrotic range proteinuria with normal kidney function and <50% crescents or sclerosing lesions on biopsy were hospitalized in the Childrens Hospital of Zhejiang University School of Medicine. They were divided into two groups: the treatment group (n = 42; Triptolide at a dosage of 1 mg/kg·d, combined with prednisone at a dosage of 2 mg/kg·d, within a course of medium-to-long-term therapy of 6 to 9 months) and the control group (n = 14; prednisone alone, with the same procedure). Results. Short-term remission was observed in 95% of patients from treatment group and in 72% of patients from control group, respectively. There was a significant difference between both groups (χ 2 = 6.222, P = 0.029) for short-term effects. Meanwhile, no significant difference, as proteinuria, hematuria, hypertension, and decreased eGFR, was observed between the two groups in long-term followup (χ 2 = 3.111, P = 0.097). The Kaplan-Meier plot analysis also revealed no significant difference (χ 2 = 2.633, P = 0.105). Conclusion. Triptolide is effective in relieving short-term symptoms for moderately severe HSPN children, though its long-term effects need to be observed further.

Triple immunosuppressive therapy in steroid-resistant nephrotic syndrome children with tacrolimus resistance or tacrolimus sensitivity but frequently relapsing.

The treatment strategy for steroid‐resistant nephrotic syndrome remains uncertain at present, especially in those with calcineurin inhibitor resistance or intolerance. To date, few studies have been published using multiple combination therapy of immunosuppressive reagents for children with calcineurin inhibitor‐resistant or ‐intolerant nephrotic syndrome.

Overexpression of Myo1e in Mouse Podocytes Enhances Cellular Endocytosis, Migration, and Adhesion

Podocytes are a terminally differentiated and highly specialized cell type in the glomerulus that forms a crucial component of the glomerular filtration barrier. Recently, Myo1e was identified in the podocytes of glomeruli. Myo1e podocyte‐specific knockout mice exhibit proteinuria, podocyte foot process effacement, glomerular basement membrane disorganization, signs of chronic renal injury, and kidney inflammation. After overexpression of Myo1e in a conditionally immortalized mouse podocyte cell line (MPC5), podocyte migration was evaluated via transwell assay, endocytosis was evaluated using FITC‐transferrin, and adhesion was evaluated using a detachment assay after puromycin aminonucleoside treatment. Myo1e overexpression significantly increased the adherence of podocytes. ANOVA analysis indicated significant differences for cell adhesion between the overexpression and control groups (overexpression vs. control, t = 11.3199, P = 0.005; overexpression vs. negative control, t = 12.0570, P = 0.0006). Overexpression of Myo1e inhibited puromycin aminonucleoside‐induced podocyte detachment, and the number of cells remaining on the bottom of the culture plate increased. Cell migration was enhanced in Myo1e‐overexpressing podocytes in the transwell migration assay. Internalization of FITC‐transferrin also increased in Myo1e‐overexpressing podocytes relative to control cells. Overexpression of Myo1e can enhance podocyte migration ability, endocytosis, and attachment to the glomerular basement membrane. Restoration of Myo1e expression in podocytes may therefore strengthen their functional integrity against environmental and mechanical injury. J. Cell. Biochem. 115: 410–419, 2014.

24h Urinary Protein Levels and Urine Protein/Creatinine Ratios Could Probably Forecast the Pathological Classification of HSPN

This study aimed to assess the relevance of laboratory tests in Henoch-Schönlein purpura nephritis (HSPN) classification, and determine accurate classification factors. This prospective study included 694 HSPN patients who underwent ultrasound-guided percutaneous renal biopsy (PRB). Renal specimens were scored according to International Study of Kidney Disease in Children (ISKDC) classification. Meanwhile, blood samples were immediately collected for laboratory examination. The associations between laboratory parameters and HSPN classification were assessed. Significant differences in levels of serum Th1/Th2 cytokines, immunoglobulins, T-lymphocyte subsets, complement, and coagulation markers were obtained between HSPN patients and healthy children. Interestingly, 24h urinary protein (24h-UPRO) levels and urine protein/urine creatinine ratios could determine HPSN grade IIb, IIIa, and IIIb incidences, with areas under ROC curve of 0.767 and 0.731, respectively. At 24h-UPRO >580.35mg/L, prediction sensitivity and specificity were 75.2% and 70.0%, respectively. These values became 53.0% and 82.3%, respectively, with 24h-UPRO exceeding 1006.25mg/L. At urine protein/urine creatinine > 0.97, prediction sensitivity and specificity were 65.5% and 67.2%, respectively, values that became 57.4% and 80.0%, respectively, at ratios exceeding 1.2. Cell and humoral immunity, coagulation and fibrinolytic systems are all involved in the pathogenesis of HSPN, and type I hypersensitivity may be the disease trigger of HSPN. 24h-UPRO levels and urine protein/creatinine ratios could probably forecast the pathological classification of HSPN.

Familial steroid-sensitive idiopathic nephrotic syndrome: seven cases from three families in China

OBJECTIVES: Familial steroid-sensitive idiopathic nephrotic syndrome is rare, and only approximately 3% of patients have affected siblings. METHODS: Herein, we report seven cases of patients with steroid-sensitive idiopathic nephrotic syndrome from three Chinese families. Mutational screening of the Nphs2 gene was performed in all the patients. RESULTS: All seven of the familial steroid-sensitive idiopathic nephrotic syndrome cases in our sample exhibited minimal change disease, and one case also presented with mesangial proliferative glomerulonephritis, according to the renal pathology. No significant was associations were found between Nphs2 gene mutations and the onset of proteinuria and nephrotic syndrome in these familial cases. CONCLUSIONS: The presence of minimal change disease is important, but it is not an unusual finding in patients with familial steroid-sensitive idiopathic nephrotic syndrome, which appears to be clinically benign and genetically distinct from other types of nephrosis.

Clinical Characteristics of Concomitant Nephrotic IgA Nephropathy and Minimal Change Disease in Children

Background: IgA nephropathy (IgAN) is the most common primary glomerulonephritis in children and adolescents worldwide. Meanwhile, minimal change disease (MCD) is the most common cause of nephrotic syndrome in children. Recently, several case reports have revealed that IgAN can be complicated by MCD in adults. Here, we report our experience concerning the features of such patients in pediatrics. Methods: The clinical manifestations and pathological features of 197 children who presented with IgAN from December 2007 to November 2013 were analyzed retrospectively based on the criteria for nephrotic syndrome and MCD. Results: Among the 197 children diagnosed with primary IgAN, 25 (12.7%) patients presented with nephrotic syndrome, and 7 patients (2.8%) presented with MCD-like pathological features and nephrotic syndrome simultaneously. The cohort of 7 patients included 5 boys, and the median age was 8.9. All of the patients who were diagnosed with primary nephrotic syndrome were treated initially with corticosteroids. Except for 1 patient with steroid resistance who was lost to follow-up, the other 6 cases presented were steroid sensitive and remained in complete remission for the last follow-up, with median and mean follow-up durations of 30.5 and 34.5 months, respectively (range 10-65 months). Conclusions: This study revealed that IgAN and MCD may also coexist in children. Moreover, most of these patients who presented with nephrotic syndrome responded well to steroids and had a favorable prognosis. Large-scale studies are required, and careful attention should be paid to such complicated cases.

The Value of Monitoring the Serum Concentration of Mycophenolate Mofetil in Children with Steroid-Dependent/Frequent Relapsing Nephrotic Syndrome

Background: Mycophenolate mofetil (MMF) is an alternative treatment strategy in children with steroid sensitivity who have frequent relapses or steroid-dependent nephrotic syndrome (FRNS/SDNS). Methods: From January 2009 to January 2015, 31 cases of children with FRNS/SDNS were prospectively recruited and administered MMF and prednisone; then, serum samples were collected, and the area under the curve (AUC) of mycophenolic acid (MPA-AUC) was calculated. Results: A MPA-AUC of 27.99 μg·h/ml had a diagnostic sensitivity of 65.2% and a specificity of 87.5% in discriminating relapsing from non-relapsing patients (receiver operating characteristic-AUC 0.848). The 31 patients were then grouped according to the results of the MPA-AUC as follows: low-AUC group, <30 μg·h/ml and high-AUC group, ≥30 μg·h/ml. The results indicated that there was a significant difference in the remission rate between the groups (χ2 = 6.645, p = 0.01) during the 6 months of follow-up. Compared with the results before MMF therapy, the steroid dosage in both groups was significantly reduced at the 6- and 12-month follow-ups. Furthermore, the steroid dose was reduced more significantly in the high-AUC group than in the low-AUC group (0.447 ± 0.254 vs. 0.219 ± 0.161 mg/kg/day, p = 0.006) at the 6-month follow-up. Compared with the low-AUC group at the 6-month follow-up, the number of patients with relapse and relapse episodes in the high-AUC group were also significantly reduced (7/16 vs. 1/15, p = 0.037, and 15/27 vs. 1/29, p = 0.014, respectively). Conclusions: MMF is a reasonable treatment choice to reduce the number of relapse episodes and steroid administration in children with FRNS/SDNS. Moreover, children in the high-AUC group (MPA-AUC ≥30 μg·h/ml) tended to require lower steroid doses and had greater remission rates than the patients in the low-AUC group (<30 μg·h/ml) at the 6-month follow-up.

Evaluation of mycophenolate mofetil or tacrolimus in children with steroid sensitive but frequently relapsing or steroid‐dependent nephrotic syndrome

Approximately 30–40% of children with steroid sensitive nephrotic syndrome have frequently relapsing nephrotic syndrome (FRNS) or steroid‐dependent nephrotic syndrome (SDNS). Mycophenolate mofetil (MMF) and tacrolimus (TAC) are often alternative treatment choices for these patients.

Lack of association between NPHS2 gene polymorphisms and sporadic IgA nephropathy

Aim:  IgA nephropathy (IgAN) is the most common primary form of glomerulonephritis worldwide. In the present study, the genetic structure of the NPHS2 gene was studied to verify if podocin plays a role in the pathogenesis of IgAN.