Toshiharu Ueno

Aberrant Notch1-dependent effects on glomerular parietal epithelial cells promotes collapsing focal segmental glomerulosclerosis with progressive podocyte loss

Collapsing focal segmental glomerulosclerosis (cFSGS) is a progressive kidney disease characterized by glomerular collapse with epithelial hyperplasia. Here we used a transgenic mouse model of cFSGS with immunotoxin-induced podocyte-specific injury to determine the role for Notch signaling in its pathogenesis. The mice exhibited progressive loss of podocytes and severe proteinuria concomitant with histological features of cFSGS. Hyperplastic epithelium was negative for genetic podocyte tags, but positive for the parietal epithelial cell marker claudin-1, and expressed Notch1, Jagged1, and Hes1 mRNA and protein. Enhanced Notch mRNA expression induced by transforming growth factor-β1 in cultured parietal epithelial cells was associated with mesenchymal markers (α-smooth muscle actin, vimentin, and Snail1). Notch inhibition in vitro suppressed these phenotypic transcripts and Notch-dependent cell migration. Moreover, Notch inhibition in vivo significantly decreased parietal epithelial cell lesions but worsened proteinuria and histopathology in our cFSGS model. Thus, aberrant Notch1-mediated parietal epithelial cell migration with phenotypic changes appears to underlie the pathogenesis of cFSGS. Parietal epithelial cell hyperplasia may also represent an adaptive response to compensate for a disrupted filtration barrier with progressive podocyte loss.

Prognostic Value of Tubulointerstitial Lesions, Urinary N-Acetyl-β-d-Glucosaminidase, and Urinary β2-Microglobulin in Patients with Type 2 Diabetes and Biopsy–Proven Diabetic Nephropathy

BACKGROUND AND OBJECTIVES Some biomarkers of renal tubular injury are reported to be useful for predicting renal prognosis in the early stage of diabetic nephropathy (DN). Our study compared predictions of the renal prognosis by such biomarkers and by histologic tubulointerstitial damage. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Among 210 patients with type 2 diabetes and biopsy-proven DN managed from 1985 to 2011, 149 patients with urinary N-acetyl-β-d-glucosaminidase (NAG) and urinary β2-microglobulin (β2-MG) data at the time of renal biopsy were enrolled. The primary outcome was a decline in eGFR of ≥50% from baseline or commencement of dialysis for ESRD. RESULTS The median follow-up period was 2.3 years (interquartile range, 1.1-5.3), and the primary outcome was noted in 94 patients. Mean eGFR was 46.3±23.2 ml/min per 1.73 m(2), and 132 patients (89%) had overt proteinuria at baseline. Cox proportional hazards analysis revealed that the association of urinary NAG and β2-MG with the outcome was attenuated after adjustment for known promoters of progression (+1 SD for log NAG: hazard ratio [HR], 1.14; 95% confidence interval [95% CI], 0.84 to 1.55; +1 SD for log β2-MG: HR, 1.23; 95% CI, 0.94 to 1.62). In contrast, the interstitial fibrosis and tubular atrophy (IFTA) score was still significantly correlated with the outcome after adjustment for the same covariates (+1 for IFTA score: HR, 2.31; 95% CI, 1.56 to 3.43). Moreover, adding the IFTA score to a model containing known progression indicators improved prediction of the outcome (increase of concordance index by 0.02; 95% CI, 0.00 to 0.05; category-free net reclassification improvement by 0.54; 95% CI, 0.03 to 1.05; and relative integrated discrimination improvement by 0.07; 95% CI, -0.08 to 0.22). CONCLUSIONS Adding urinary NAG and β2-MG excretion to known promoters of progression did not improve prognostication, whereas adding the IFTA score did. The IFTA score may be superior to these tubulointerstitial markers for predicting the renal prognosis in advanced DN.

Podocyte injury-driven intracapillary plasminogen activator inhibitor type 1 accelerates podocyte loss via uPAR-mediated β1-integrin endocytosis.

Podocyte-endothelial cell cross-talk is paramount for maintaining the filtration barrier. The present study investigated the endothelial response to podocyte injury and its subsequent role in glomerulosclerosis using the podocyte-specific injury model of NEP25/LMB2 mice. NEP25/LMB2 mice showed proteinuria and local podocyte loss accompanied by thrombotic microangiopathy on day 8. Mice showed an increase of glomerular plasminogen activator inhibitor type 1 (PAI-1) mRNA and aberrant endothelial PAI-1 protein already on day 1, before thrombosis and proteinuria. A PAI-1-specific inhibitor reduced proteinuria and thrombosis and preserved podocyte numbers in NEP25/LMB2 mice by stabilization of β1-integrin translocation. Heparin loading significantly reduced thrombotic formation, whereas proteinuria and podocyte numbers were unchanged. Immortalized podocytes treated with PAI-1 and the urokinase plasminogen activator (uPA) complex caused significant cell detachment, whereas podocytes treated with PAI-1 or uPA alone or with the PAI-1/uPA complex pretreated with an anti-uPA receptor (uPAR) antibody failed to cause detachment. Confocal microscopy and cell surface biotinylation experiments showed that internalized β1-integrin was found together with uPAR in endocytotic vesicles. The administration of PAI-1 inhibitor or uPAR-blocking antibody protected cultured podocytes from cell detachment. In conclusion, PAI-1/uPA complex-mediated uPAR-dependent podocyte β1-integrin endocytosis represents a novel mechanism of glomerular injury leading to progressive podocytopenia. This aberrant cross-talk between podocytes and endothelial cells represents a feedforward injury response driving podocyte loss and progressive glomerulosclerosis.

Clinical and pathological predictors of estimated GFR decline in patients with type 2 diabetes and overt proteinuric diabetic nephropathy

The effect of clinical and pathological parameters on the estimated glomerular filtration rate (eGFR) decline has not been investigated in patients with type 2 diabetes and overt proteinuric biopsy‐proven diabetic nephropathy.

Left Ventricular Mass Index Is an Independent Determinant of Diastolic Dysfunction in Patients on Chronic Hemodialysis: A Tissue Doppler Imaging Study

Background: Diastolic heart failure is the most common clinical form of heart failure. Tissue Doppler imaging (TDI) is often used to quantitate left ventricular (LV) diastolic function. The purpose of this study was to identify the determinant(s) of diastolic dysfunction in patients with end-stage renal disease on hemodialysis (HD), using the TDI method. Methods: The study subjects were 53 patients with end-stage renal disease and preserved LV systolic function on maintenance HD. LV function was assessed by conventional echocardiography. The ratio of early trans-mitral flow velocity to early mitral annular velocity (E/e′) was measured by TDI. Patients were stratified into two groups based on E/e′ value (≤15 and >15 groups). Arterial stiffness was evaluated by pulse wave velocity and cardio-ankle vascular index. Results: Patients of the E/e′ >15 group were older (p = 0.025). There were no significant differences in blood pressure, ejection fraction, E/A, deceleration time, and pulse wave velocity between the E/e′ >15 and E/e′ ≤15 groups. However, there were significant differences in LV mass index (LVMI; p < 0.001) and cardio-ankle vascular index (p = 0.048) between the two groups. Multiple regression analysis identified that LVMI was an independent determinant of E/e′ (p = 0.003). Conclusions:Our findings suggest that LVMI is an independent determinant of LV diastolic dysfunction in patients on HD.

Remission of proteinuria and preservation of renal function in patients with renal AA amyloidosis secondary to rheumatoid arthritis

BACKGROUND Renal AA amyloidosis presents as a life-threatening disease in patients with rheumatoid arthritis (RA). Although several newly developed immunosuppressive drugs have been tried, patients often progress to end-stage renal failure with unsatisfactory survival rate. METHODS A total of nine consecutive cases of severe nephrotic renal AA amyloidosis presented to us. Complete remission of proteinuria was observed in four cases (responders), and the remaining five reached the end point of haemodialysis or death (non-responders); these groups were retrospectively compared. The patients were treated with immunosuppressants, biological drugs and anti-hypertensive drugs. Levels of serum creatinine (S-Cr), urinary protein-creatinine ratio (UP/UCr), blood pressure (BP) and C-reactive protein (CRP) were measured. Histological characteristics of renal amyloid deposition and extent of kidney injury were also scored. RESULTS Prior to treatment, clinical data (S-Cr, UP/UCr, BP and CRP) and histological severity (glomerular sclerosis, tubulointerstitial injury and extent of amyloid deposition) observed in the renal biopsy specimen were not significantly different between the groups. Following therapeutic intervention, proteinuria disappeared (UP/UCr <0.3) in responders within 12 ± 5.4 months but persisted in non-responders. Consequently, renal function stabilized in responders, but it deteriorated in all non-responders. Strict inflammatory control along with optimal control of hypertension was achieved in responders during the treatment. CONCLUSION Regardless of histological severity, intensive therapeutic intervention that includes strict inflammatory control and optimal control of hypertension may change the histology-predicted prognosis of RA-associated renal AA amyloidosis.

Suitability of Patients with Autosomal Dominant Polycystic Kidney Disease for Renal Transcatheter Arterial Embolization

In patients with autosomal dominant polycystic kidney disease (ADPKD), massive renal enlargement is a serious problem. Renal transcatheter arterial embolization (TAE) can reduce renal volume (RV), but effectiveness varies widely, and the reasons remain unclear. We investigated factors affecting renal volume reduction rate (RVRR) after renal TAE in all 449 patients with ADPKD who received renal TAE at Toranomon Hospital from January of 2006 to July of 2013, including 228 men and 221 women (mean age =57.0±9.1 years old). One year after renal TAE, the RVRR ranged from 3.9% to 84.8%, and the least squares mean RVRR calculated using a linear mixed model was 45.5% (95% confidence interval [95% CI], 44.2% to 46.8%). Multivariate analysis using the linear mixed model revealed that RVRR was affected by the presence of large cysts with wall thickening (regression coefficient [RC], -6.10; 95% CI, -9.04 to -3.16; P<0.001), age (RC, -0.82; 95% CI, -1.03 to -0.60; P<0.001), dialysis duration (RC, -0.10; 95% CI, -0.18 to -0.03; P<0.01), systolic BP (RC, 0.39; 95% CI, 0.19 to 0.59; P<0.001), and the number of microcoils used for renal TAE (RC, 1.35; 95% CI, 0.83 to 1.86; P<0.001). Significantly more microcoils were needed to achieve renal TAE in patients with younger age and shorter dialysis duration. In conclusion, cyst wall thickening had an important effect on cyst volume reduction. Renal TAE was more effective in patients who were younger, had shorter dialysis duration, or had hypertension, parameters that might associate with cyst wall stiffness and renal artery blood flow.

Clinical implications of linear immunofluorescent staining for immunoglobulin G in patients with diabetic nephropathy

AIMS The kidneys of patients with diabetes mellitus usually exhibit a characteristic pattern of linear immunofluorescent staining for immunoglobulin G (IgG) along the glomerular and tubular basement membranes. However, the association between linear IgG staining and the renal prognosis remains unclear. METHODS Among 223 patients with diabetes who underwent renal biopsy from 1985 to 2010 and were confirmed to have pure diabetic nephropathy according to the classification of Tervaert et al., 165 patients (glomerular classes I to III) were enrolled in this study. Immunofluorescent staining was classified into three categories according to its intensity (0=none, 1=weakly positive, and 2=positive). Cox proportional hazards regression analysis was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for death-censored renal death, with each regression analysis employing four levels of multivariate adjustment. RESULTS After adjustment for important clinical factors at the time of renal biopsy, the HR for death-censored renal death in patients with an IgG staining score of 1 or 2 was, respectively, 3.01 (95% CI: 1.05-8.68) and 4.68 (1.67-13.1) compared with patients who had a staining score of 0. Even after adjustment for clinical variables and pathological findings, the HR for IgG score of 1 or 2 was higher than that for an IgG score of 0, and it was, respectively, 2.22 (0.71-7.00) and 3.76 (1.27-11.2). CONCLUSIONS More intense linear IgG staining is associated with a higher HR for renal death, which suggests that linear immunofluorescent staining for IgG may be a prognostic indicator in patients with diabetic nephropathy.

Peritoneal Dialysis is Limited by Kidney and Liver Volume in Autosomal Dominant Polycystic Kidney Disease.

We evaluated the influence of kidney volume (KV) and liver volume (LV) on continuation of peritoneal dialysis (PD) in patients with autosomal dominant polycystic kidney disease (PKD). Twenty‐two PKD patients on PD were retrospectively investigated after being divided into two groups. Group 1 comprised 15 patients who started PD at our hospital and group 2 was composed of seven patients referred from other hospitals for treatment of renomegaly by transcatheter arterial embolization (TAE) at 47.1 ± 21.8 months after commencing PD. In group 1, KV for both kidneys (mean ± SD) was 2787 ± 1945 mL (range: 1043 to 6816 mL), LV was 2198 ± 1139 mL (1005 to 4116 mL), and the total organ volume (TV = KV + LV) was 4985 ± 1815 mL (2320 to 8912 mL). In the patient with the largest TV from group 1 (KV of 6816 mL, TV of 8912 mL, and TV/BMI ratio of 426, PD was stopped due to dialysate leakage. However, dialysate leakage did not occur in the other 14 patients (TV ≦ 7963 mL and TV/BMI ratio of 353 at the start of PD). In group 2, KV was 5822 ± 1597 mL (3832 to 8862 mL), LV was 1776 ± 519 mL (1271 to 2671 mL), and TV was 7597 ± 1431 mL (5505 to 10358) before TAE. Leakage of dialysate did not occur with a mean infusion volume of 1530 ± 370 mL (1000 mL to 2000 mL), even after renomegaly and hepatomegaly progressed to the maximum TV/BMI ratio of 359. Six patients from the two groups developed new abdominal hernias at 36 ± 5 months (6–55 months) after starting PD. These findings suggest that performance of PD may be limited by renomegaly and hepatomegaly in patients with PKD.

Clinicopathological analysis of allogeneic hematopoietic stem cell transplantation–related membranous glomerulonephritis☆☆☆

Allogeneic hematopoietic stem cell transplantation (HSCT)-related membranous glomerulonephritis (MGN) is poorly understood. A total of 830 patients who underwent HSCT at Toranomon Hospital from 2000 to 2012 were evaluated retrospectively, including 621 patients receiving umbilical cord blood transplantation (UCBT) and 208 patients receiving unrelated bone marrow transplantation. MGN was diagnosed in 5 patients after UCBT (versus none after bone marrow transplantation) and occurred concomitantly with chronic graft-versus-host disease after cessation of immunosuppression. Light microscopy did not show any definite spikes or bubbling of the glomerular basement membrane (GBM) in all 5 patients. In 1 patient (case 5), endocapillary proliferative lesions with fibrin-like deposits were noted in addition to MGN findings. Immunofluorescence demonstrated granular deposits of immunoglobulin G (IgG; IgG1 and IgG4) along the GBM with negativity for C3, C4, and C1q in 4 patients (cases 1-4), whereas case 5 showed positivity for IgG (IgG1, IgG2, IgG3, and IgG4) as well as for C3, C4, and C1q. Electron microscopy revealed electron-dense deposits in the subepithelial space of the GBM in cases 1-4. In case 5, electron-dense deposits were present in the mesangium and the subendothelial space of the GBM, as well as in the subepithelial space. After treatment with immunosuppressants (prednisolone and/or cyclosporin) or angiotensin-converting enzyme inhibitors, complete remission with disappearance of proteinuria was achieved 12.2 months in all 5 patients, but nephrotic-range proteinuria relapsed in 2 patients during follow-up. Serum anti-PLA2R autoantibody was negative in 3 patients. HSCT-related MGN only occurred after UCBT. We believe that there were 2 morphologic patterns: early MGN and membranoproliferative pattern glomerulonephritis.