Autosomic Dominant Tubulo Interstitial Kidney Disease: Case Report of a New Variant of the UMOD Gene.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a low-prevalence pathology mainly associated with pathogenic variants of the UMOD gene. It is characterized by the progressive deterioration of renal function, associated with hyperuricemia and accompanied by a family history of gout or hyperuricemia. Often, clinical variability and a lack of molecular testing results in diagnostic failure to determine the ADTKD-UMOD association. Case presentation: We describe the case of a 14-year-old male who presented to the nephrology service with hyperuricemia, renal ultrasonographic changes, and progression to chronic kidney disease in 4 years. He had a family history of hyperuricemia. A probable genetic disease with an autosomal dominant inheritance pattern was considered, confirmed by the presence of a probably pathogenic variant of the UMOD gene, not previously reported in the literature. Conclusion: The investigation of this case led to the identification of a new variant in the UMOD gene, broadening the spectrum of known variants for ADTKD-UMOD. In addition, in this case, a comprehensive anamnesis, that takes into account family history, was the key point to carry out genetic tests that confirmed the diagnosis suspicion. Directed Genetic tests are currently an essential diagnostic tool and should be performed as long as they are available and there is an indication to perform them.

Acute kidney injury in a mouse model of meningococcal disease.

INTRODUCTION: Meningococcal disease is associated with high mortality. When acute kidney injury (AKI) occurs in patients with severe meningococcal disease, it is typically attributable to sepsis, although meningococcal disease and lipopolysaccharide release are rarely investigated. Therefore, we evaluated renal tissue in a mouse model of meningococcal disease. METHODS: Female BALB/c mice were induced to AKI by meningococcal challenge. Markers of renal function were evaluated in infected and control mice. RESULTS: In the infected mice, serum concentrations of tumor necrosis factor alpha, interferon gamma, interleukins (IL-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, and IL-12), and granulocyte-macrophage colony-stimulating factor were elevated, as was renal interstitial infiltration with lymphocytes and neutrophils (p < 0.01 for the latter). Histological analysis showed meningococcal microcolonies in the renal interstitium, without acute tubular necrosis. Infected mice also showed elevated renal expression of toll-like receptor 2, toll-like receptor 4, and Tamm-Horsfall protein. The expression of factors in the intrinsic pathway of apoptosis was equal to or lower than that observed in the control mice. Urinary sodium and potassium were also lower in infected mice, probably due to a tubular defect. CONCLUSION: Our findings corroborate those of other studies of AKI in sepsis. To our knowledge, this is the first time that meningococci have been identified in renal interstitium and that the resulting apoptosis and inflammation have been evaluated. However, additional studies are needed in order to elucidate the mechanisms involved.

Serum Uromodulin Predicts Less Coronary Artery Calcification and Diabetic Kidney Disease Over 12 Years in Adults With Type 1 Diabetes: The CACTI Study.

OBJECTIVE: Novel biomarkers are needed to better predict coronary artery calcification (CAC), a marker of subclinical atherosclerosis, and diabetic kidney disease (DKD) in type 1 diabetes. We evaluated the associations between serum uromodulin (SUMOD [a biomarker associated with anti-inflammatory and renal protective properties]), CAC progression, and DKD development over 12 years. RESEARCH DESIGN AND METHODS: Participants (n = 527, 53% females) in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study were examined during 2002-2004, at a mean age of 39.6 ± 9.0 years and a median duration of diabetes of 24.8 years. Urine albumin-to-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) determined by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation were measured at baseline and after a mean follow-up period of 12.1 ± 1.5 years. Elevated albumin excretion was defined as ACR ≥30 mg/g, rapid GFR decline (>3 mL/min/1.73 m2/year), and impaired GFR as eGFR <60 mL/min/1.73 m2. SUMOD was measured on stored baseline plasma samples (Meso Scale Discovery). CAC was measured using electron beam computed tomography. CAC progression was defined as a change in the square root-transformed CAC volume of ≥2.5. RESULTS: Higher baseline SUMOD level conferred lower odds of CAC progression (odds ratio 0.68; 95% CI 0.48-0.97), incident elevated albumin excretion (0.37; 0.16-0.86), rapid GFR decline (0.56; 0.35-0.91), and impaired GFR (0.44; 0.24-0.83) per 1 SD increase in SUMOD (68.44 ng/mL) after adjustment for baseline age, sex, systolic blood pressure, LDL cholesterol, and albuminuria/GFR. The addition of SUMOD to models with traditional risk factors also significantly improved the prediction performance for CAC progression and incident DKD. CONCLUSIONS: Higher baseline SUMOD level predicted lower odds of both CAC progression and incident DKD over 12 years in adults with type 1 diabetes.

Identification of a novel UMOD mutation (c.163G>A) in a Brazilian family with autosomal dominant tubulointerstitial kidney disease.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is characterized by autosomal dominant inheritance, progressive chronic kidney disease, and a bland urinary sediment. ADTKD is most commonly caused by mutations in the UMOD gene encoding uromodulin (ADTKD-UMOD). We herein report the first confirmed case of a multi-generational Brazilian family with ADTKD-UMOD, caused by a novel heterozygous mutation (c.163G>A, GGC→AGC, p.Gly55Ser) in the UMOD gene. Of 41 family members, 22 underwent genetic analysis, with 11 individuals found to have this mutation. Three affected individuals underwent hemodialysis, one peritoneal dialysis, and one patient received a kidney transplant from a family member later found to be genetically affected. Several younger individuals affected with the mutation were also identified. Clinical characteristics included a bland urinary sediment in all tested individuals and a kidney biopsy in one individual showing tubulointerstitial fibrosis. Unlike most other reported families with ADTKD-UMOD, neither gout nor hyperuricemia was found in affected individuals. In summary, we report a novel UMOD mutation in a Brazilian family with 11 affected members, and we discuss the importance of performing genetic testing in families with inherited kidney disease of unknown cause.

Identification of a novel UMOD mutation (c. 163G>A) in a Brazilian family with autosomal dominant tubulointerstitial kidney disease

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is characterized by autosomal dominant inheritance, progressive chronic kidney disease, and a bland urinary sediment. ADTKD is most commonly caused by mutations in the UMOD gene encoding uromodulin (ADTKD-UMOD). We herein report the first confirmed case of a multi-generational Brazilian family with ADTKD-UMOD, caused by a novel heterozygous mutation (c.163G>A, GGC→AGC, p.Gly55Ser) in the UMOD gene. Of 41 family members, 22 underwent genetic analysis, with 11 individuals found to have this mutation. Three affected individuals underwent hemodialysis, one peritoneal dialysis, and one patient received a kidney transplant from a family member later found to be genetically affected. Several younger individuals affected with the mutation were also identified. Clinical characteristics included a bland urinary sediment in all tested individuals and a kidney biopsy in one individual showing tubulointerstitial fibrosis. Unlike most other reported families with ADTKD-UMOD, neither gout nor hyperuricemia was found in affected individuals. In summary, we report a novel UMOD mutation in a Brazilian family with 11 affected members, and we discuss the importance of performing genetic testing in families with inherited kidney disease of unknown cause.

Urinary Tamm-Horsfall protein, albumin, vitamin D-binding protein, and retinol-binding protein as early biomarkers of chronic kidney disease in dogs.

Proteinuria is a marker and mediator of chronic kidney disease (CKD). In clinical practice, the urinary protein-to-creatinine ratio (UP/C) is of limited usefulness, because it indicates only the magnitude of proteinuria and not the origin of the loss (glomerular or tubular). The complete assessment of proteinuria includes quantitative and qualitative evaluations, both of which are required in order to optimize the therapy. In addition to measuring the UP/C, we performed SDS-PAGE and western blotting to determine the expression of albumin, vitamin D-binding protein (VDBP), retinol-binding protein (RBP), and Tamm-Horsfall protein (THP) in urine samples of 49 dogs: healthy (control) dogs (n = 9); and dogs with CKD (n = 40), stratified by stage. In the dogs with stage 3 or 4 CKD, there was a predominance of tubular proteins. Neither VDBP nor RBP was observed in the urine of the control dogs. Among the dogs with stage 1 or 2 CKD, VDBP and RBP were detected in those without proteinuria or with borderline proteinuria. The expression of urinary albumin was significantly higher in the stage 4 group than in any other group (P ≤ 0.01). In the stage 4 group, urinary THP was either undetectable or lower than in the control group (P ≤ 0.01). In conclusion, urinary VDBP and RBP might act as early markers of kidney injury, and a decrease in urinary THP could be an indicator of CKD progression.

Uromodulin: a new biomarker of fetal renal function?

INTRODUCTION: Obstructive uropathies are main diseases affecting the fetus. Early diagnosis allows to establish the appropriate therapy to minimize the risk of damage to kidney function at birth. Biochemical markers have been used to predict the prognosis of renal function in fetuses. Uromodulin, also known by Tamm-Horsfall protein (THP) is exclusively produced in the kidneys and in normal conditions is the protein excreted in larger amounts in human urine. It plays important roles in kidneys and urinary tract. Also it participates in ion transport processes, interact with various components of the immune system and has a role in defense against urinary tract infections. Moreover, this protein was proved to be a good marker of renal function in adult patients with several renal diseases. OBJECTIVE: To evaluate if uromodulin is produced and eliminated by the kidneys during fetal life by analyzing fetal urine and amniotic fluid and to establish correlation with biochemical parameter of renal function already used in Fetal Medicine Center at the Clinic Hospital of UFMG (CEMEFE/HC). METHODS: Between 2013 and 2015, were selected 29 fetuses with indication of invasive tests for fetal diagnosis in monitoring at the CEMEFE/HC. RESULTS: The determination of uromodulin was possible and measurable in all samples and showed statistically significant correlation with the osmolarity. CONCLUSION: There was a tendency of lower levels of Uromodulin values in fetuses with severe renal impairment prenatally. Thus, high levels of this protein in fetal amniotic fluid or fetal urine dosages possibly mean kidney function preserved.

Uromodulin: a new biomarker of fetal renal function? / Uromodulina: um novo biomarcador de função renal fetal?

Abstract Introduction: Obstructive uropathies are main diseases affecting the fetus. Early diagnosis allows to establish the appropriate therapy to minimize the risk of damage to kidney function at birth. Biochemical markers have been used to predict the prognosis of renal function in fetuses. Uromodulin, also known by Tamm-Horsfall protein (THP) is exclusively produced in the kidneys and in normal conditions is the protein excreted in larger amounts in human urine. It plays important roles in kidneys and urinary tract. Also it participates in ion transport processes, interact with various components of the immune system and has a role in defense against urinary tract infections. Moreover, this protein was proved to be a good marker of renal function in adult patients with several renal diseases. Objective: To evaluate if uromodulin is produced and eliminated by the kidneys during fetal life by analyzing fetal urine and amniotic fluid and to establish correlation with biochemical parameter of renal function already used in Fetal Medicine Center at the Clinic Hospital of UFMG (CEMEFE/HC). Methods: Between 2013 and 2015, were selected 29 fetuses with indication of invasive tests for fetal diagnosis in monitoring at the CEMEFE/HC. Results: The determination of uromodulin was possible and measurable in all samples and showed statistically significant correlation with the osmolarity. Conclusion: There was a tendency of lower levels of Uromodulin values in fetuses with severe renal impairment prenatally. Thus, high levels of this protein in fetal amniotic fluid or fetal urine dosages possibly mean kidney function preserved.

Resumo Introdução: Uropatias obstrutivas estão entre as principais doenças que acometem o feto. O diagnóstico precoce destas doenças permite estabelecer a terapêutica adequada, visando minimizar os riscos de danos à função renal no nascimento. Os marcadores bioquímicos têm sido utilizados na predição do prognóstico da função renal em fetos. A uromodulina, também chamada de proteína de Tamm-Horsfall (THP), é produzida exclusivamente nos rins, e em condições normais, é a proteína excretada em maior volume na urina humana. Ela desempenha importantes funções nos rins e trato urinário. Participa dos processos de transporte de íons, interage com vários componentes do sistema imunológico e possui papel na defesa contra infecções do trato urinário. Além disso, se mostrou um bom biomarcador de função renal em adultos portadores de diversas doenças renais. Objetivos: Avaliar se a uromodulina é produzida e eliminada pelos rins durante a vida fetal através da análise de urina fetal e líquido amniótico, além de estabelecer correlação com o parâmetro bioquímico de função renal já utilizado no Centro de Medicina Fetal do Hospital das Clínicas da UFMG (CEMEFE/HC). Métodos: Entre 2013 e 2015, foram selecionados 29 fetos com indicação de exames invasivos para diagnóstico fetal em acompanhamento no CEMEFE/HC. Resultados: A dosagem da uromodulina foi possível e quantificável em todas as amostras e mostrou correlação significativa com a osmolaridade. Conclusão: A uromodulina mostrou uma tendência em apresentar valores reduzidos em fetos com grave comprometimento renal no pré-natal. Assim, valores elevados desta proteína em dosagens de urina fetal ou líquido amniótico podem significar uma função renal preservada.

Diagnostic capability of biological markers in assessment of obstructive sleep apnea: a systematic review and meta-analysis.

OBJECTIVE: The purpose of this systematic review is to evaluate the diagnostic value of biological markers (exhaled breath condensate, blood, salivary and urinary) in the diagnosis of OSA in comparison to the gold standard of nocturnal PSG. METHODS: Studies that differentiated OSA from controls based on PSG results, without age restriction, were eligible for inclusion. The sample of selected studies could include studies in obese patients and with known cardiac disease. A detailed individual search strategy for each of the following bibliographic databases was developed: Cochrane, EMBASE, MEDLINE, PubMed, and LILACS. The references cited in these articles were also crosschecked and a partial grey literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies. RESULTS: After a two-step selection process, nine articles were identified and subjected to qualitative and quantitative analyses. Among them, only one study conducted in children and one in adults found biomarkers that exhibit sufficiently satisfactory diagnostic accuracy that enables application as a diagnostic method for OSA. CONCLUSION: Kallikrein-1, uromodulin, urocotin-3, and orosomucoid-1 when combined have enough accuracy to be an OSA diagnostic test in children. IL-6 and IL-10 plasma levels have potential to be good biomarkers in identifying or excluding the presence of OSA in adults.

Urine biomarkers predict acute kidney injury in newborns.

OBJECTIVE: To identify urine biomarkers predictive of acute kidney injury (AKI) in infants admitted to level 2 and 3 neonatal intensive care units with birth weight >2000 g and 5-minute Apgar score ≤ 7. STUDY DESIGN: A nested case-control study was performed comparing 8 candidate urine AKI biomarkers in infants with AKI (defined as a rise in serum creatinine of at least 0.3 mg/dL or a serum creatinine elevation ≥ 1.7 mg/dL persisting for 3 days) and 24 infants from the described cohort without AKI. Urine was analyzed for neutrophil gelatinase-associated lipocalin, osteopontin, cystatin C, albumin, ß(2) microglobulin, epithelial growth factor, uromodulin (UMOD), and kidney injury molecule 1. RESULTS: Compared with the infants without AKI, those with AKI had higher levels of urine cystatin C (1123 pg/mL [95% CI, 272-4635 pg/mL] vs 90 pg/mL [95% CI, 39-205 pg/mL]; P < .004; area under the receiver operating characteristic curve [AUC] = 0.82), lower levels of UMOD (11.0 pg/mL [95% CI, 5.7-21.4 pg/mL] vs 26.2 pg/mL [95% CI, 17.4-39.4 pg/mL]; P < .03; AUC = 0.77), and lower levels of epithelial growth factor (6.7 pg/mL [95% CI, 4.0-11.3 pg/mL] vs 17.4 pg/mL [95% CI, 12.7-23.8 pg/mL; P = .003; AUC = 0.82). Although the differences were not statistically significant, levels of urine neutrophil-associated gelatinase lipocalin, kidney injury molecule 1, and osteopontin trended higher in infants with AKI. CONCLUSION: Urinary biomarkers can predict AKI in neonates admitted to level 2 and 3 neonatal intensive care units.

Effect of an isotonic rehydration sports drink and exercise on urolithiasis in rats.

The objective of the present study was to evaluate the role of physical exercise as well as the influence of hydration with an isotonic sports drink on renal function in male Wistar rats. Four groups were studied over a period of 42 days: 1) control (N = 9); 2) physical exercise (Exe, N = 7); 3) isotonic drink (Drink, N = 8); 4) physical exercise + isotonic drink (Exe + Drink, N = 8). Physical exercise consisted of running on a motor-driven treadmill for 1 h/day, at 20 m/min, 5 days a week. The isotonic sports drink was a commercial solution used by athletes for rehydration after physical activity, 2 ml administered by gavage twice a day. Urine cultures were performed in all animals. Twenty-four-hour urine samples were collected in metabolic cages at the beginning and at the end of the protocol period. Urinary and plasma parameters (sodium, potassium, urea, creatinine, calcium) did not differ among groups. However, an amorphous material was observed in the bladders of animals in the Exe + Drink and Drink groups. Characterization of the material by Western blot revealed the presence of Tamm-Horsfall protein and angiotensin converting enzyme. Physical exercise and the isotonic drink did not change the plasma or urinary parameters measured. However, the isotonic drink induced the formation of intravesical matrix, suggesting a potential lithogenic risk.

Role of Tamm-Horsfall protein and uromodulin in calcium oxalate crystallization.

One of the defenses against nephrolithiasis is provided by macromolecules that modulate the nucleation, growth, aggregation and retention of crystals in the kidneys. The aim of the present study was to determine the behavior of two of these proteins, Tamm-Horsfall and uromodulin, in calcium oxalate crystallization in vitro. We studied a group of 10 male stone formers who had formed at least one kidney stone composed of calcium oxalate. They were classified as having idiopathic nephrolithiasis and had no well-known metabolic risk factors involved in kidney stone pathogenesis. Ten normal men were used as controls, as was a group consisting of five normal women and another consisting of five pregnant women. Crystallization was induced by a fixed supersaturation of calcium oxalate and measured with a Coulter Counter. All findings were confirmed by light and scanning electron microscopy. The number of particulate material deposited from patients with Tamm-Horsfall protein was higher than that of the controls (P<0.001). However, Tamm-Horsfall protein decreased the particle diameter of the stone formers when analyzed by the mode of the volume distribution curve (P<0.002) (5.64 +/- 0.55 microm compared to 11.41 +/- 0.48 microm of uromodulin; 15.94 +/- 3.93 microm and 12.45 +/- 0.97 microm of normal men Tamm-Horsfall protein and uromodulin, respectively; 8.17 +/- 1.57 microm and 9.82 +/- 0.95 microm of normal women Tamm-Horsfall protein and uromodulin, respectively; 12.17 +/- 1.41 m and 12.99 +/- 0.51 microm of pregnant Tamm-Horsfall protein and uromodulin, respectively). Uromodulin produced fewer particles than Tamm-Horsfall protein in all groups. Nonetheless, the total volume of the crystals produced by uromodulin was higher than that produced by Tamm-Horsfall protein. Our results indicate a different effect of Tamm-Horsfall protein and uromodulin. This dual behavior suggests different functions. Tamm-Horsfall protein may act on nucleation and inhibit crystal aggregation, while uromodulin may promote aggregation of calcium oxalate crystals.

Tamm-Horsfall protein excretion to predict the onset of renal insufficiency.

OBJECTIVE: Immunosuppressive therapy after liver transplantation may be a risk for kidney dysfunction. This work was designed to determine whether Tamm-Horsfall Protein (THP) could be considered as a marker for nephrotoxicity. DESIGN AND METHODS: THP was determined by an ELISA method in serial 24-h urine from liver transplant patients. Fourteen patients suffered renal insufficiency (LTr(1)) and 20 showed no acute renal damage (LTr(2)) after liver transplantation. RESULTS: No clear association could be seen between daily THP excretion and plasma creatinine levels by comparing serial samples collected at the same time. Nevertheless, significant differences were observed in pretransplant THP excretion between both groups of patients. The results (Median/Interquartile Range) were: CONTROLS: 113.2/84.9 to 146.8 mg/24 h (n = 30); LTr(1): 36.9/18.3 to 54.5 mg/24 h (p<<0.001 with respect to C and LTr(2)); LTr(2): 90.8/61.5 to 139.7 mg/24 h. CONCLUSIONS: The higher pretransplant synthesis and/or secretion of THP seem to have a protective role on the kidney during and after liver transplantation.

Endogenous vasopressin regulates Na-K-ATPase and Na(+)-K(+)-Cl(-) cotransporter rbsc-1 in rat outer medulla.

Previous reports have shown a stimulatory effect of vasopressin (VP) on Na-K-ATPase and rBSC-1 expression and activity. Whether these VP-dependent mechanisms are operating in vivo in physiological conditions as well as in chronic renal failure (CRF) has been less well studied. We measured ATPase expression and activity and rBSC-1 expression in the outer medulla of controls and moderate CRF rats both before and under in vivo inhibition of VP by OPC-31260, a selective V(2)-receptor antagonist. OPC-31260 decreased Na-K-ATPase activity from 11.2 +/- 1.5 to 3.7 +/- 0.8 in controls (P < 0.05) and from 19.0 +/- 0.8 to 2.9 +/- 0.5 micromol P(i). mg protein(-1) x h(-1) in moderate CRF rats (P < 0.05). CRF was associated with a significant increase in Na-K-ATPase activity (P < 0.05). Similarly, CRF was also associated with a significant increase in Na-K-ATPase expression to 164.4 +/- 21.5% compared with controls (P < 0.05), and OPC-31260 decreased Na-K-ATPase expression in both controls and CRF rats to 57.6 +/- 9.5 and 105.3 +/- 10.9%, respectively (P < 0.05). On the other hand, OPC-31260 decreased rBSC-I expression in both controls and CRF rats to 60.8 +/- 6.5 and 30.0 +/- 6.9%, respectively (P < 0.05), and was not influenced by CRF (95.7 +/- 5.2%). We conclude that 1) endogenous VP modulated Na-K-ATPase and rBSC-1 in both controls and CRF; and 2) CRF was associated with increased activity and expression of the Na-K-ATPase in the outer medulla, in contrast to the unaltered expression of the rBSC-1. The data suggest that endogenous VP could participate in the regulation of electrolyte transport at the level of the outer medulla.

Role of Tamm-Horsfall protein in the binding and in vivo phagocytosis of type 1 fimbriated Escherichia coli by mouse peritoneal macrophages.

Tamm-Horsfall glycoprotein (THP) contains manno-oligosaccharides that are recognized by type 1 fimbriae (F1) of Escherichia coli. In the present study, we examined the in vivo phagocytic activity of mouse peritoneal macrophages after treatment of bacteria with THP. At low THP concentrations (12.5 microg/ml and 50 microg/ml) no significant difference was observed in the phagocytosis of E. coli F1+. However, at high THP concentrations (500 microg/ml and 1250 microg/ml) we obtained a reduction of bacterial phagocytosis by mouse peritoneal macrophages.

Massive intratubular hemorrhage with herniations into renal veins: report of a case.

A 24-year-old man had unilateral gross hematuria that required nephrectomy. Pathological examination revealed massive intratubular hemorrhage and frequent deposition of an amorphous and homogeneous material positive for periodic acid, Schiff stain in the corticomedullary junction. This substance had the characteristics of Tamm-Horsfall protein and frequently herniated into the lumen of thin-walled veins of arcuate size. There was no apparent cause for the bleeding. To the best of our knowledge this is the third reported case with these peculiar findings and no apparent cause. We discuss some hypotheses as to the etiopathogenesis of this rare and intriguing condition.