The Association of Urinary Sclerostin and Renal Magnesium Handling in Type 2 Diabetic Patients with Chronic Kidney Disease.

INTRODUCTION: Sclerostin could enhance renal excretion of calcium (Ca) and phosphate (P). The association between sclerostin and magnesium (Mg) has not yet discovered. In patients with type 2 diabetes mellitus (T2DM) or chronic kidney disease (CKD), higher serum sclerostin and altered renal excretion of Ca, P, and Mg were detected. Therefore, we tried to evaluate if there was any association between sclerostin and fractional excretion of Ca, P, and Mg (FeCa, FeP, and FeMg) in T2DM with CKD. METHODS: In this prospective cohort study, 43 T2DM patients without CKD or with CKD stage 1-5 were enrolled. Values of parameters, including serum and urine sclerostin, were collected at baseline and 6 months later. For baseline data, the Mann-Whitney U test, χ2 test, or Spearman's correlation were used. For multivariate repeated measurement analysis, generalized estimating equation (GEE) model was utilized. RESULTS: Patients with lower estimated glomerular filtration rate had higher serum sclerostin, FeP, FeMg, and lower FeCa. By correlation analysis, serum sclerostin was negatively associated with FeCa (p = 0.02) and positively associated with FeP (p = 0.002). The urine sclerostin to creatinine ratio (Uscl/Ucre) was positively correlated with FeP (p = 0.007) and FeMg (p = 0.005). After multivariate analyses by GEE model, serum sclerostin was still inversely associated with FeCa, while Uscl/Ucre was significantly associated with FeMg. On the other hand, FeP lost its associations with serum sclerostin or Uscl/Ucre. CONCLUSION: In our study population of T2DM patients with or without CKD, the inverse correlation between serum sclerostin and FeCa could not be explained by the calciuric effect of sclerostin. In addition, a newly discovered positive association between urinary sclerostin and FeMg indicated a possible role of urinary sclerostin in regulating renal Mg handling especially over distal convoluted tubules.

Urinary Dickkopf-3 and Contrast-Associated Kidney Damage.

BACKGROUND: Administration of iodinated contrast medium (CM) during invasive cardiovascular procedures may be associated with impairment of kidney function. OBJECTIVES: Urinary dickkopf-3 (DKK3), a stress-induced renal tubular epithelium-derived glycoprotein, has been identified as a biomarker predicting both acute kidney injury (AKI) and persistent kidney dysfunction. METHODS: Urinary DKK3/creatinine ratio (uDKK3/uCr), urine and serum neutrophil gelatinase-associated lipocalin (uNGAL, sNGAL) and serum cystatin C (sCyC) were assessed in 458 patients with chronic kidney disease scheduled for invasive cardiovascular procedures requiring CM administration with universal adoption of nephroprotective interventions. Contrast-associated AKI (CA-AKI) was defined as serum creatinine increase ≥0.3 mg/dl at 48 h after CM administration. Persistent kidney dysfunction was defined as persistent estimated glomerular filtration rate reduction ≥25% at 1 month compared with baseline. RESULTS: CA-AKI occurred in 64 or the 458 patients (14%), and baseline uDKK3/uCr ≥491 pg/mg was the best threshold for its prediction. Net reclassification improvement (NRI) was significantly increased by adding baseline uDKK3/uCr to the Mehran, Gurm, and National Cardiovascular Data Registry (NCDR) scores (all p < 0.05), and the same applied to integrated discrimination improvement (IDI) when adding uDKK3/uCr to the Gurm and NCDR scores (p < 0.001). Persistent kidney dysfunction occurred in 57 of the 458 patients (12%) and baseline uDKK3/uCr ≥322 pg/mg appeared as the best threshold for its prediction. Adding baseline uDKK3/uCr to the Mehran, Gurm, and NCDR scores significantly increased IDI and NRI (all p < 0.001). CONCLUSIONS: Baseline uDKK3/uCr seems to be a reliable marker for improving the identification of patients with chronic kidney disease undergoing invasive coronary and peripheral procedures at risk for AKI and persistent kidney dysfunction.

Biomarkers of Contrast-Induced Nephropathy:: Which Ones are Clinically Important?

Contrast-induced acute kidney injury (CI-AKI) is a common complication after intravascular injection of iodinated contrast media, and it is associated with a prolonged in-hospital stay and unfavorable outcome. CI-AKI occurs in 5% to 20% among hospitalized patients. Its diagnosis relies on the increase in serum creatinine levels, which is a late biomarker of kidney injury. Novel and early serum and urinary biomarkers have been identified to detect kidney damage before the expected serum creatinine increase.

Urinary podocyte-associated molecules and albuminuria in hypertension.

OBJECTIVE: Hypertension-induced podocyte damage and the relationship with UAE is analyzed in diabetic and nondiabetic participants. PATIENTS AND METHODS: Sixty-four hypertensive patients, 30 diabetics, with glomerular filtration rate (eGFR) greater than 60 ml/min per 1.73 m were included. Urinary albumin excretion was measured in morning urine using a nephelometric immunoassay and expressed as albumin/creatinine ratio. Urinary pellets were obtained from fresh urine and mRNA was assessed by real-time quantitative PCR. Likewise, protein podocyte-specific molecules were measured by western blot using specific antibodies. RESULTS: Fourteen nondiabetics and 20 diabetics had increased UAE greater than 30 mg/g. In individuals with increased EUA, the mRNA expression of nephrin and CD2AP was low in diabetics, whereas only nephrin mRNA in nondiabetics. No differences were observed in podocalyxin and aquaporin-1 mRNA levels. Concerning the protein values, in both nondiabetic and diabetic patients, nephrin, CD2AP and podocalyxin were increased in patients with increased UAE, with no differences in aquaporin-1. A significant positive relationship was observed between log UAE and nephrin protein values, and an inverse association observed with mRNA. CONCLUSION: Hypertensive patients who had elevated UAE showed increased urinary excretion of podocyte-specific proteins coupled with a phenotype of decreased mRNA expression. The phenotype of podocyte-specific mRNA and the increment of nephrin can be used as a valuable marker of early glomerular injury.

Influence of hematuria and infection on diagnostic accuracy of urinary LASP1: a new biomarker for bladder carcinoma.

AIM: To further promote the clinical use of urinary LASP1 as biomarker for urothelial carcinoma of the bladder regarding limitations and alternative testing systems. PATIENTS & METHODS: Urine stabilization, alternative measurement systems and limitations by erythrocyte contamination and infection were investigated in 246 patients. RESULTS: Thimerosal allowed sufficient stabilization. Fluorescence-activated cell sorting analysis was not influenced by presence of erythrocytes or leukocytes and reliably urothelial carcinoma of the bladder but cell counts in specimen were low. Cut-off values of <25 leukocytes and <200 erythrocytes/µl resulted in sensitivity, specificity, positive and negative predictive values of 0.59, 0.80, 0.80 and 0.59, respectively. CONCLUSION: Hematuria up to 200 erythrocytes/µl but not presence of leukocytes may be tolerated for this promising marker.

CD2AP mRNA in urinary exosome as biomarker of kidney disease.

AIMS: Podocyte injury plays an important role in the pathogenesis of kidney disease. Urinary exosomes are microvesicles released by tubular epithelial cells and podocytes containing information of their originated cells. This study investigated for the first time whether podocyte related mRNA in urinary exosome could serve as novel biomarkers for kidney disease. METHODS: Urine samples were collected from 32 patients of kidney disease who underwent kidney biopsy and 7 controls. CD2AP, NPHS2 and synaptopodin were detected by real-time RT-PCR on RNA isolated from urinary exosome. RESULTS: The pellet microvesicles were positively stained with exosome and podocyte marker, AQP2, CD9 and nephrin. CD2AP mRNA was lower (p=0.008) in kidney disease patients compared with controls and decreased with the increasing severity of proteinuria (p=0.06). CD2AP correlated with serum creatinine (r=-0.373, p=0.035), BUN (r=-0.445, p=0.009) and eGFR (r=0.351, p=0.046). Neither NPHS2 nor synaptopodin correlated with parameters of renal function. CD2AP mRNA correlated negatively with 24 hour urine protein (r=-0.403, p=0.022), severity of tubulointerstitial fibrosis (r=-0.394, p=0.026) and glomerulosclerosis (r=-0.389, p=0.031) and could discriminate kidney disease from controls with AUC of 0.821 (p=0.008). CONCLUSIONS: Urinary exosome mRNA of CD2AP might be a non-invasive tool for detecting both renal function and fibrosis of kidney disease.

[Value of combined detection of urinary Livin and Survivin mRNA expression in the early diagnosis of bladder cancer].

OBJECTIVE: To evaluate the value of urine Livin and Survivin mRNA expression in the early diagnosis of bladder cancer. METHODS: Fifty-two cases of early bladder cancer and 30 cases of non-urinary system tumors were selected for the combined detection of urinary Livin and Survivin and urine cytology. RESULTS: Livin and Survivin in urine and urinary cytology sensitivity were 71.2% (37/52) , 67.3% (35/52), 23.1% (12/52); Specificity were 96.7% (29/30) , 93.3% (28/30) and 96.7% (29/30) respectively. Urine Survivin sensitivity, specificity compared with Livin were no significant difference (all P > 0.05). Urinary Livin and Survivin were more sensitive than urine cytology, and the differences were statistically significant(all P < 0.05). CONCLUSION: The combined urinary detection of Livin, Survivin mRNA expression is a noninvasive early diagnosis of bladder cancer with sensitivity and specificity.

LASP-1, a novel urinary marker for detection of bladder cancer.

OBJECTIVES: The LIM and SH3 (LASP)-1 protein is a focal adhesion protein that has been linked to oncogenesis. The aim of this study was to evaluate the diagnostic use of the detection of LASP-1 in tumor specimens and in urine for noninvasive detection of transitional cell carcinoma (TCC). MATERIALS AND METHODS: Immunohistochemical staining for LASP-1 was performed on 72 archived bladder tumor specimens, and LASP-1 content was measured in 132 spontaneous urine sample sediments by Western blot analysis. RESULTS: In the histologic specimens, immunohistochemical staining for LASP-1 showed abundant expression throughout the urothelium of the bladder and ureter. However, modest overexpression of LASP-1 was observed in the TCC specimens. Measurement of the LASP-1 protein concentrations in urinary cell pellets from healthy donors and bladder cancer patients was highly sensitive for the presence of TCC. The cut-off value was determined by receiver operating characteristic (ROC) analysis. When a cut-off value of 1 ng LASP-1/500 µl of urine was used, the sensitivity, specificity, and positive and negative predictive values of the assay were 83.1%, 85.3%, 83.1%, and 80.6%, respectively.The increased urinary LASP-1 content in TCC patients was attributable in part to a specific increase in cell shedding presumably caused by changes in cell adhesion, as confirmed by LASP-1 knockdown. Contamination with erythrocytes above 250 cells/µl and urinary infection gave false positive results and are therefore sample exclusion criteria. CONCLUSIONS: In the absence of urinary infection or gross hematuria, urinary LASP-1 level is a promising marker for transitional cell carcinoma.

Microalbuminuria in type 1 diabetes is associated with enhanced excretion of the endocytic multiligand receptors megalin and cubilin.

OBJECTIVE: Proteinuria is the hallmark of diabetic nephropathy; yet, glomerular histology does not fully explain mechanisms contributing to proteinuria. Our objective was to identify proteins in the urine of individuals with type 1 diabetes and microalbuminuria that might implicate a mechanistic pathway operative in proteinuria. RESEARCH DESIGN AND METHODS: Using a GeLC/MS platform proteomics approach, we compared the urine proteome from 12 healthy nondiabetic individuals, 12 subjects with type 1 diabetes yet normal urinary albumin excretion rates, and 12 subjects with type 1 diabetes and microalbuminuria (type 1 diabetes + microalbuminuria). RESULTS: The abundance of megalin and cubilin, two multiligand receptors expressed in kidney proximal tubule cells and involved with the reuptake of filtered albumin and megalin/cubilin ligands, was significantly increased in type 1 diabetes + microalbuminuria urine, compared with both nonalbuminuric groups. CONCLUSIONS: Aberrant shedding of megalin and cubilin could contribute to albuminuria in diabetes and to deficiency states of important vitamins and hormones.