Angiotensinogen and interleukin 18 in serum and urine of children with kidney cysts.

BACKGROUND: The most common disease associated with the presence of kidney cysts in the population is autosomal dominant polycystic kidney disease (ADPKD), which finally leads to end-stage renal disease. METHOD: The study evaluated serum and urinary concentration of angiotensinogen (AGT) and interleukin 18 (IL-18) in a group of 39 children with renal cysts of different aetiology. RESULTS: Serum and urinary AGT concentration in children with renal cysts was higher compared to controls, regardless of the underlying background and gender. Serum IL-18 concentration was lower, in contrast, and the concentration of IL-18 in the urine did not differ between affected and healthy children. Negative correlation between urinary IL-18 concentration and systolic and mean arterial blood pressure was noted. CONCLUSIONS: Higher AGT levels in serum and urine in children with renal cysts may indicate the activation of the renin-angiotensin-aldosterone system, including its intrarenal part, even before the onset of hypertension. Lower serum concentration of IL-18 in children with kidney cysts may indicate the loss of the protective role of this cytokine with the occurrence of hypertension.

Urinary proteome signature of Renal Cysts and Diabetes syndrome in children.

Renal Cysts and Diabetes Syndrome (RCAD) is an autosomal dominant disorder caused by mutations in the HNF1B gene encoding for the transcriptional factor hepatocyte nuclear factor-1B. RCAD is characterized as a multi-organ disease, with a broad spectrum of symptoms including kidney abnormalities (renal cysts, renal hypodysplasia, single kidney, horseshoe kidneys, hydronephrosis), early-onset diabetes mellitus, abnormal liver function, pancreatic hypoplasia and genital tract malformations. In the present study, using capillary electrophoresis coupled to mass spectrometry (CE-MS), we investigated the urinary proteome of a pediatric cohort of RCAD patients and different controls to identify peptide biomarkers and obtain further insights into the pathophysiology of this disorder. As a result, 146 peptides were found to be associated with RCAD in 22 pediatric patients when compared to 22 healthy age-matched controls. A classifier based on these peptides was generated and further tested on an independent cohort, clearly discriminating RCAD patients from different groups of controls. This study demonstrates that the urinary proteome of pediatric RCAD patients differs from autosomal dominant polycystic kidney disease (PKD1, PKD2), congenital nephrotic syndrome (NPHS1, NPHS2, NPHS4, NPHS9) as well as from chronic kidney disease conditions, suggesting differences between the pathophysiology behind these disorders.

New insights into the role of HNF-1ß in kidney (patho)physiology.

Hepatocyte nuclear factor-1ß (HNF-1ß) is an essential transcription factor that regulates the development and function of epithelia in the kidney, liver, pancreas, and genitourinary tract. Humans who carry HNF1B mutations develop heterogeneous renal abnormalities, including multicystic dysplastic kidneys, glomerulocystic kidney disease, renal agenesis, renal hypoplasia, and renal interstitial fibrosis. In the embryonic kidney, HNF-1ß is required for ureteric bud branching, initiation of nephrogenesis, and nephron segmentation. Ablation of mouse Hnf1b in nephron progenitors causes defective tubulogenesis, whereas later inactivation in elongating tubules leads to cyst formation due to downregulation of cystic disease genes, including Umod, Pkhd1, and Pkd2. In the adult kidney, HNF-1ß controls the expression of genes required for intrarenal metabolism and solute transport by tubular epithelial cells. Tubular abnormalities observed in HNF-1ß nephropathy include hyperuricemia with or without gout, hypokalemia, hypomagnesemia, and polyuria. Recent studies have identified novel post-transcriptional and post-translational regulatory mechanisms that control HNF-1ß expression and activity, including the miRNA cluster miR17 ∼ 92 and the interacting proteins PCBD1 and zyxin. Further understanding of the molecular mechanisms upstream and downstream of HNF-1ß may lead to the development of new therapeutic approaches in cystic kidney disease and other HNF1B-related renal diseases.

Changes in the urinary extracellular vesicle proteome are associated with nephronophthisis-related ciliopathies.

Nephronophthisis is one of the leading genetic causes of end-stage renal disease in childhood. Early diagnostics and prognostics for nephronophthisis are currently limited. We aimed to identify non-invasive protein biomarkers for nephronophthisis in urinary extracellular vesicles. Extracellular vesicles were isolated from urine of 12 patients with a nephronophthisis-related ciliopathy and 12 age- and gender-matched controls, followed by in-depth label-free LC-MS/MS proteomics analysis of gel fractionated extracellular vesicle proteins. Supervised cluster analysis of proteomic profiles separated patients from controls. We identified 156 differentially expressed proteins with fold change ≥4 in patients compared to controls (P < .05). Importantly, expression levels of discriminating proteins were correlated with chronic kidney disease stage, suggesting possible applications for urinary extracellular vesicle biomarkers in prognostics for nephronophthisis. Enrichment analysis of gene ontology terms revealed GO terms including signaling, actin cytoskeleton and endocytosis among the downregulated proteins in patients, whereas terms related to response to wounding and extracellular matrix organization were enriched among upregulated proteins. Our findings represent the first step towards a non-invasive diagnostic test for nephronophthisis. Further research is needed to determine specificity of the candidate biomarkers. In conclusion, proteomic profiles of urinary extracellular vesicles differentiate nephronophthisis-related ciliopathy patients from healthy controls. SIGNIFICANCE: Nephronophthisis is an important cause of end-stage renal disease in children and is associated with an average diagnostic delay of 3.5 years. This is the first study investigating candidate biomarkers for nephronophthisis using global proteomics analysis of urinary extracellular vesicles in patients with nephronophthisis compared to control individuals. We show that measuring protein markers in urinary extracellular vesicles is a promising approach for non-invasive early diagnostics of nephronophthisis.

Expression of renal cystic genes in patients with HNF1B mutations.

BACKGROUND/AIMS: HNF1B nephropathy is characterized by dominantly inherited renal hypodysplasia with few cysts, slow renal decline and hypomagnesemia. Mice with antenatal inactivation of HNF1B are characterized by polycystic kidneys, renal failure and a profound decrease in cystic gene (Pkhd1, Umod, Pkd2) expression. Mice with inactivation after postnatal day 10 have no renal phenotype. METHODS: Quantification of mRNA expression of HNF1B, six of its potential target genes (PKHD1, PKD1, PKD2, IFT88, TMEM27 and UMOD) and three genes involved in the Mg(2+) renal homeostasis (ATP1A1, FXYD2 and CLDN16) in the urinary sediment of 11 individuals with mutation of HNF1B and in 9 controls (non-invasive assessment of the renal transcriptome). RESULTS: As compared to controls, no difference was observed in the urinary mRNA amount of HNF1B and the renal cystic genes. A significant increase in the expression of ATP1A1, which encodes the α1-subunit of the Na(+)/K(+)-ATPase, was identified in HNF1B patients consistent with its role in Mg(2+) homeostasis. CONCLUSION: Assessment of mRNA expression in urinary sediment is a non-invasive method applicable to gain insights into the pathophysiology of inherited nephropathies in humans. HNF1B nephropathy is generally not associated with postnatal down-expression of renal cystic genes in human, a finding consistent with mouse models.

[Urinary TGF-beta1 excretion in children with renal cysts]. / Wydalanie TGF-beta1 w moczu dzieci z torbielowatoscia nerek.

UNLABELLED: Autosomal dominant polycystic disease is characterised by abnormal polycystin, protein, which is a component of basement membrane and extracellular matrix. Transforming growth factor (TGF-beta1) is a cytokine, which takes part in development of renal tubule epithelium and stimulates the synthesis of extracellular matrix proteins. The aim of work was the assessment of TGF-beta1 concentration in children with renal polycystic disease. MATERIAL AND METHODS: The examined group (I) consisted of 33 children aged (median 14.7 years, range 4.0-17.9): A--11 children with solitary cyst, B--22 with polycystic renal disease. Control group (C) consisted of 20 healthy children at the same age. The concentration of urinary TGF-b1 was measured using immunoenzymatic ELISA method. The results showed that mean concentration of urinary TGF-beta 1 (121.9 +/- 168 pg/mg cr.) was lower than in group B, in which it was 207.2 +/- 361 pg/mg cr. However the difference was not statistically significant (p>0.05). In both subgroups (A and B) urinary excretion of TGF-beta1 was higher than in control group (C) (p<0.05). In 4 (36%) children from group A and 8 (36%) from group B the urinary concentration of TGF-beta 1 was below the sensitivity of the method. No correlation between TGF-beta 1 and children's age, urinary osmolality and GRF according to Schwartz was found. It was a positive correlation between urinary TGF-betal concentration and total diameter of renal cysts. CONCLUSIONS: TGF-betal takes part in renal cyst formation and increased urinary excretion of TGF-b1 in proportion to the dimension of renal cysts may be an evidence of that fact.

Medullary cystic kidney disease with hyperuricemia and gout in a large Cypriot family: no allelism with nephronophthisis type 1.

We describe a large Cypriot family with an interstitial type of nephropathy, inherited as an autosomal dominant trait that led to end stage renal failure between 51 to 78 years of age (mean 62.2 years). Twenty-three people are known to be affected, but several younger relatives with normal renal function may remain undiagnosed because of the absence of precise clinical and laboratory diagnostic criteria. This nephropathy is associated with medullary renal cysts, hypertension, hyperuricemia, and gout. Several relatives have typical medullary cystic disease (MCD), while in the others the findings are compatible with this diagnosis. Due to the similarity of clinical and pathologic findings, earlier reports had suggested that MCD may be allelic to autosomal recessive familial juvenile nephronophthisis, which was mapped recently to chromosome band 2q13. Linkage analysis of the present family with a closely linked marker excluded linkage to the above locus. Linkage was also excluded to the PKD1 locus of adult polycystic kidney disease type 1, and up to 5 cM on either side, on chromosome 16. We suggest that because of the element of hyperuricemia and gout found in this family, although with reduced penetrance, it may represent a variant of autosomal dominant MCD of the adult type. This variability may be the result of allelic or locus heterogeneity. Molecular genetic approaches including linkage analysis on appropriate families will certainly assist in classifying such related genetically heterogeneous disorders.

[Change in prostanoid metabolism in cystic kidney lesion]. / Izmenenie metabolizma prostanoidov pri kistoznom porazhenii pochek.

A wide range of renal prostaglandins in cysts has been studied as compared with their content in the daily urine, activity of plasma renin, level of adrenocorticotropic hormone (ACTH) in the tissues, methionine enkephalin and aldosterone. High activity of renin, met-enkephalin and ACTH was observed in the patients with one cyst. Under renal polycystosis the activity of plasma renin is higher and the amount of ACTH positively decreases. The comparison of prostanoids content in the cystic fluid of a single cyst and polycystic one demonstrates that the polycystic level of all prostanoids in the punctate increase 2-3 times.

The urine urokinase concentration in end stage renal disease with acquired renal cyst.

To see whether there was any difference in the urine urokinase concentration between acquired cystic kidney disease (ACKD) group and control (non cyst) group in end stage renal disease patients (ESRD), we evaluated fifty ESRD patients who had been maintained on chronic hemodialysis for various period. The urine urokinase concentration was higher in the ACKD group (17.5 +/- 14.7 unit/ml, range 13.5-47.0 unit/ml, n = 9) than the control group (4.1 +/- 3.4 unit/ml, range 0.5-12.0 unit/ml, n = 36) (p less than 0.001), and polycyst group (2.6 +/- 1.8 unit/ml, range 1.0-5.1 unit/ml, n = 5) (p less than 0.01). But there was no difference between the control group and polycyst group. In the control group and the ACKD group, there was a direct relation between the dialysis duration and the urokinase concentration and the longer the dialysis duration, the higher the urine urokinase concentration (r squared = 0.424, p = 0.0001). The hemodialysis duration was longer in the ACKD group (42 +/- 17.0 months) than the control group (20.0 +/- 12.5 months) (p less than 0.005). These findings suggest that urokinase may be responsible for cystogenic degeneration in ESRD.

[Clinical study of asymptomatic microhematuria].

A statistical survey was performed on 200 patients with asymptomatic microhematuria who visited our hospital between January 1986 and October 1989. Urinalysis, urinary cytology, urinary culture, IVP, echography and cystoscopy were carried out for the evaluation of the origin and nature of the microhematuria. In 92 patients (46%), urological abnormalities were observed. Among them, urological lesions requiring medical and surgical treatments were found in 28 patients (14%) including two malignant cases of bladder tumor. No urologic lesion could be identified in 108 patients (54%). The degree of hematuria was unrelated to the seriousness of its cause. Thirteen of 28 patients (46%) with diseases that required treatment had under 5 red blood cells per high power field on the microscopic urinalysis. Therefore, complete urologic investigation of all patients with any degree of asymptomatic microhematuria is recommended.

Urinary milk of calcium in children and adults: use of gravity-dependent sonography.

Fifteen cases with urinary milk of calcium (UMC) are presented, all of them secondary to urinary obstruction: ureteropelvic junction stenosis (three cases), staghorn calculus (two), caliceal diverticulum (five), and pyelogenic cyst (five). Four patients (aged 7-19) are the youngest with this affliction reported to date. Milk of calcium proximal to a staghorn calculus has not been described previously. Gravity-dependent sonography was the most efficient and sensitive method of diagnosis. Follow-up of 1-16 years showed the formation and gradual increase in the quantity of UMC without evidence of gross calculus formation within the milk. In two patients, there was spontaneous, partial drainage of UMC.

Nephronophthisis with massive proteinuria.

A 23-year-old male whose uncle died of nephronophthisis, and whose pathology is also discussed, presented with 5 g of protein in a 24-hour urine collection. Nephrogenic diabetes insipidus and salt wasting were present in addition to azotemia. Characterization of the proteinuria, including elevated alpha globulins by electrophoresis and markedly elevated urinary beta-microglobulins by radioimmunoassay (49.55 mg/L) indicated predominantly tubular proteinuria. A percutaneous renal biopsy showed normal glomeruli, interstitial inflammation and fibrosis, and tubular atrophy. Electron microscopy revealed notable alterations of the tubular basement membrane.