Podocyte autophagy is associated with foot process effacement and proteinuria in patients with minimal change nephrotic syndrome.

Autophagy is a cellular mechanism involved in the bulk degradation of proteins and turnover of organelle. Several studies have shown the significance of autophagy of the renal tubular epithelium in rodent models of tubulointerstitial disorder. However, the role of autophagy in the regulation of human glomerular diseases is largely unknown. The current study aimed to demonstrate morphological evidence of autophagy and its association with the ultrastructural changes of podocytes and clinical data in patients with idiopathic nephrotic syndrome, a disease in which patients exhibit podocyte injury. The study population included 95 patients, including patients with glomerular disease (minimal change nephrotic syndrome [MCNS], n = 41; idiopathic membranous nephropathy [IMN], n = 37) and 17 control subjects who underwent percutaneous renal biopsy. The number of autophagic vacuoles and the grade of foot process effacement (FPE) in podocytes were examined by electron microscopy (EM). The relationships among the expression of autophagic vacuoles, the grade of FPE, and the clinical data were determined. Autophagic vacuoles were mainly detected in podocytes by EM. The microtubule-associated protein 1 light chain 3 (LC3)-positive area was co-localized with the Wilms tumor 1 (WT1)-positive area on immunofluorescence microscopy, which suggested that autophagy occurred in the podocytes of patients with MCNS. The number of autophagic vacuoles in the podocytes was significantly correlated with the podocyte FPE score (r = -0.443, p = 0.004), the amount of proteinuria (r = 0.334, p = 0.033), and the level of serum albumin (r = -0.317, p = 0.043) in patients with MCNS. The FPE score was a significant determinant for autophagy after adjusting for the age in a multiple regression analysis in MCNS patients (p = 0.0456). However, such correlations were not observed in patients with IMN or in control subjects. In conclusion, the results indicated that the autophagy of podocytes is associated with FPE and severe proteinuria in patients with MCNS. The mechanisms underlying the activation of autophagy in association with FPE in podocytes should be further investigated in order to elucidate the pathophysiology of MCNS.

Urine 5MedC, a Marker of DNA Methylation, in the Progression of Chronic Kidney Disease.

BACKGROUND: Alterations in DNA methylation may be involved in disease progression in patients with chronic kidney disease (CKD). Recent studies have suggested that 5-methyl-2'-deoxycytidine (5MedC) may be a marker of hypermethylation of DNA. Currently, there is no information available regarding the urine levels of 5MedC and its association with the progression of CKD. METHOD: We examined the urine levels of 5MedC in spot urine samples from 308 patients with CKD (median age: 56 years, male: 53.2%, and glomerulonephritis: 51.0%) using a competitive enzyme-linked immunosorbent assay and investigated the relationships among urine 5MedC, urine albumin, urine α1-microglobulin (α1MG), and the laboratory parameters associated with CKD. The patients were followed for three years to evaluate renal endpoints in a prospective manner. RESULTS: The urine 5MedC level was significantly increased in the later stages of CKD compared to the early to middle stages of CKD. In multiple logistic regression models, urine 5MedC was significantly associated with the prediction of later CKD stages. Urine 5MedC (median value, 65.9 µmol/gCr) was significantly able to predict a 30% decline in the estimated GFR or a development of end-stage renal disease when combined with macroalbuminuria or an increased level of urine α1MG (median value, 5.7 mg/gCr). CONCLUSION: The present data demonstrate that the urine 5MedC level is associated with a reduced renal function and can serve as a novel and potent biomarker for predicting the renal outcome in CKD patients. Further studies will be necessary to elucidate the role of urine DNA methylation in the progression of CKD.

Renal expression of trefoil factor 3 mRNA in association with tubulointerstitial fibrosis in IgA nephropathy.

AIM: Trefoil factor 3 (TFF3) is a small peptide that is involved in mucosal protection. TFF3 is widely expressed in multiple tissues including kidney tissue. Previous studies have reported that the levels of urinary TFF3 are significantly increased in patients with chronic kidney disease. The aim of this study is to detect the TFF3 mRNA in kidney and elucidate the relationship between renal TFF3 mRNA and tubulointerstitial fibrosis in IgA nephropathy (IgAN). METHODS: We investigated the renal mRNA expression of TFF3 by real-time PCR analysis in biopsy specimens from patients with IgAN, other glomerulonephritis (OGN) and minor glomerular abnormalities (MGA). We also determined the renal localization of TFF3 and the levels of urinary TFF3 by immunostaining and ELISA, respectively. RESULTS: The renal TFF3 mRNA expression was significantly associated with the urinary TFF3 secretion and the tubulointerstitial fibrosis score in the IgAN group alone. Immunostaining of the renal specimen of IgAN patients revealed that TFF3 is located in the renal tubular epithelial cells. The locations were almost the same as those that showed uromodulin positivity; specifically, the thick ascending limb (TAL) of the loop of Henle and the early portion of the distal tubule. The urinary TFF3 levels were positively correlated with the levels of urinary biomarkers of tubulointerstitial injury in such patients. CONCLUSION: Renal TFF3 mRNA is associated with renal tubulointerstitial fibrosis in IgAN patients. The TFF3 located in the renal tubular epithelial cells may play a role in the progression of tubulointerstitial fibrosis in IgAN patients.

Urine Trefoil Factors as Prognostic Biomarkers in Chronic Kidney Disease.

INTRODUCTION: Trefoil factor family (TFF) peptides are increased in serum and urine in patients with chronic kidney disease (CKD). However, whether the levels of TFF predict the progression of CKD remains to be elucidated. METHODS: We determined the TFF levels using peptide-specific ELISA in spot urine samples and performed a prospective cohort study. The association between the levels of urine TFFs and other urine biomarkers as well as the renal prognosis was analyzed in 216 CKD patients (mean age: 53.7 years, 47.7% female, 56.9% with chronic glomerulonephritis, and mean eGFR: 58.5 ml/min/1.73 m2). RESULTS: The urine TFF1 and TFF3 levels significantly increased with the progression of CKD stages, but not the urine TFF2 levels. The TFF1 and TFF3 peptide levels predicted the progression of CKD ≥ stage 3b by ROC analysis (AUC 0.750 and 0.879, resp.); however, TFF3 alone predicted CKD progression in a multivariate logistic regression analysis (odds ratio 3.854, 95% confidence interval 1.316-11.55). The Kaplan-Meier survival curves demonstrated that patients with a higher TFF1 and TFF3 alone, or in combination with macroalbuminuria, had a significantly worse renal prognosis. CONCLUSION: The data suggested that urine TFF peptides are associated with renal progression and the outcomes in patients with CKD.

IgA Nephropathy Complicated with X-linked Thrombocytopenia.

Renal involvement is occasionally observed in Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). It has been reported that galactose-deficient IgA is a closely linked to IgA nephropathy (IgAN), suggesting that patients with XLT/WAS associated with reduced galactosylation on serum IgA are susceptible to IgAN. It is necessary to pay more attention to patients with IgAN due to the potential complication with XLT/WAS. We here present a patient of XLT complicated with mild IgAN who underwent tonsillectomy combined with steroid pulse therapy to achieve complete clinical remission.

Serum cystatin C is an independent biomarker associated with the renal resistive index in patients with chronic kidney disease.

Cystatin C is a cysteine protease inhibitor that is produced by nearly all human cells. The serum level of cystatin C is a stronger predictor of the renal outcome and the risk of cardiovascular events than the creatinine level. The resistive index (RI) on renal Doppler ultrasonography is a good indicator of vascular resistance as well as the renal outcomes in patients with chronic kidney disease (CKD). However, it is unclear whether serum cystatin C is associated with signs of vascular dysfunction, such as the renal RI. We measured the serum cystatin C levels in 101 CKD patients and investigated the relationships between cystatin C and markers of vascular dysfunction, including the renal RI, ankle-brachial pulse wave velocity (baPWV), intima-media thickness (IMT), and cardiac function. The renal RI was significantly correlated with the serum cystatin C level (p < 0.0001, r = 0.6920). The serum cystatin C level was found to be a significant determinant of the renal RI (p < 0.0001), but not the baPWV, in a multivariate regression analysis. The multivariate odds ratio of the serum cystatin C level for a renal RI of more than 0.66 was statistically significant (2.92, p = 0.0106). The area under the receiver-operating characteristic curve comparing the sensitivity and specificity of cystatin C for predicting an RI of more than 0.66 was 0.882 (cutoff value: 2.04 mg/L). In conclusion, the serum cystatin C level is an independent biomarker associated with the renal RI in patients with CKD.

Arterial Stiffness is an Independent Risk Factor for Anemia After Percutaneous Native Kidney Biopsy.

BACKGROUND/AIMS: Bleeding is the most common complication after renal biopsy. Although numerous predictors of bleeding have been reported, it remains unclear whether arterial stiffness affects bleeding complications. METHOD: We performed an observational study of the renal biopsies performed in our division over an approximately 6-year period (May 2010 to May 2016). The clinical and laboratory factors were analyzed to reveal the risk factors associated with bleeding, with a focus on anemia (defined as a ≥10% decrease in hemoglobin [Hb] after biopsy). The brachial-ankle pulse wave velocity (baPWV) was measured to evaluate arterial stiffness. RESULTS: This study included 462 patients (male, n=244; female, n=218). Anemia (defined above) was observed in 54 patients (11.7%). The risk of anemia was higher in women, older patients, and patients with lower serum albumin, lower eGFR and lower diastolic blood pressure after biopsy. We then performed a further analysis of 187 patients whose baPWV data were available. Multivariate analysis revealed that a higher baPWV was an independent risk factor for anemia. ROC analysis for predicting anemia found that a baPWV value of 1839 cm/s had the best performance (AUC 0.689). CONCLUSION: An increased baPWV may be a more valuable predictor of bleeding than any of the other reported risk factors.