Gestational diabetes mellitus induces congenital anomalies of the kidney and urinary tract in mice by altering RET/MAPK/ERK pathway.

Gestational diabetes mellitus (GDM) presents a substantial population health concern. Previous studies have revealed that GDM can ultimately influence nephron endowment. In this study, we established a GDM mouse model to investigate the embryological alterations and molecular mechanisms underlying the development of congenital anomalies of the kidney and urinary tract (CAKUT) affected by GDM. Our study highlights that GDM could contribute to the manifestation of CAKUT, with prevalent phenotypes characterized by isolated hydronephrosis and duplex kidney complicated with hydronephrosis in mice. Ectopic ureteric buds (UBs) and extended length of common nephric ducts (CNDs) were noted in the metanephric development stage. The expression of Ret and downstream p-ERK activity were enhanced in UBs, which indicated the alteration of RET/MAPK/ERK pathway may be one of the mechanisms contributing to the increased occurrence of CAKUT associated with GDM.

5-HT3 Signaling Alters Development of Sacral Neural Crest Derivatives That Innervate the Lower Urinary Tract.

The autonomic nervous system derives from the neural crest (NC) and supplies motor innervation to the smooth muscle of visceral organs, including the lower urinary tract (LUT). During fetal development, sacral NC cells colonize the urogenital sinus to form pelvic ganglia (PG) flanking the bladder neck. The coordinated activity of PG neurons is required for normal urination; however, little is known about the development of PG neuronal diversity. To discover candidate genes involved in PG neurogenesis, the transcriptome profiling of sacral NC and developing PG was performed, and we identified the enrichment of the type 3 serotonin receptor (5-HT3, encoded by Htr3a and Htr3b). We determined that Htr3a is one of the first serotonin receptor genes that is up-regulated in sacral NC progenitors and is maintained in differentiating PG neurons. In vitro cultures showed that the disruption of 5-HT3 signaling alters the differentiation outcomes of sacral NC cells, while the stimulation of 5-HT3 in explanted fetal pelvic ganglia severely diminished neurite arbor outgrowth. Overall, this study provides a valuable resource for the analysis of signaling pathways in PG development, identifies 5-HT3 as a novel regulator of NC lineage diversification and neuronal maturation in the peripheral nervous system, and indicates that the perturbation of 5-HT3 signaling in gestation has the potential to alter bladder function later in life.

Generation of patterned kidney organoids that recapitulate the adult kidney collecting duct system from expandable ureteric bud progenitors.

Current kidney organoids model development and diseases of the nephron but not the contiguous epithelial network of the kidney's collecting duct (CD) system. Here, we report the generation of an expandable, 3D branching ureteric bud (UB) organoid culture model that can be derived from primary UB progenitors from mouse and human fetal kidneys, or generated de novo from human pluripotent stem cells. In chemically-defined culture conditions, UB organoids generate CD organoids, with differentiated principal and intercalated cells adopting spatial assemblies reflective of the adult kidney's collecting system. Aggregating 3D-cultured nephron progenitor cells with UB organoids in vitro results in a reiterative process of branching morphogenesis and nephron induction, similar to kidney development. Applying an efficient gene editing strategy to remove RET activity, we demonstrate genetically modified UB organoids can model congenital anomalies of kidney and urinary tract. Taken together, these platforms will facilitate an enhanced understanding of development, regeneration and diseases of the mammalian collecting duct system.

A Review of Mullerian Anomalies and Their Urologic Associations.

Structural anomalies of the female reproductive tract, known as Mullerian anomalies, can occur in isolation or in association with anomalies of other organ systems. Due to shared embryology, the most common association in up to 40% of patients is with renal, ureteral, and bladder anomalies. Affected girls can have a wide range of genitourinary symptoms with urologists playing an integral role in their diagnosis and treatment. To facilitate the recognition and management of these conditions, we provide a review of Mullerian anomalies including the embryology, classifications, syndromes, evaluation, and treatments with attention to their urologic applicability.

Expansion of Human iPSC-Derived Ureteric Bud Organoids with Repeated Branching Potential.

Ureteric bud (UB) is the embryonic kidney progenitor tissue that gives rise to the collecting duct and lower urinary tract. UB-like structures generated from human pluripotent stem cells by previously reported methods show limited developmental ability and limited branching. Here we report a method to generate UB organoids that possess epithelial polarity and tubular lumen and repeat branching morphogenesis. We also succeed in monitoring UB tip cells by utilizing the ability of tip cells to uptake very-low-density lipoprotein, cryopreserving UB progenitor cells, and expanding UB tip cells that can reconstitute the organoids and differentiate into collecting duct progenitors. Moreover, we successfully reproduce some phenotypes of multicystic dysplastic kidney (MCDK) using the UB organoids. These methods will help elucidate the developmental mechanisms of UB branching and develop a selective differentiation method for collecting duct cells, contributing to the creation of disease models for congenital renal abnormalities.

Interobserver Reliability of the Antenatal Consensus Classification System for Urinary Tract Dilatation.

OBJECTIVES: The consensus classification system for urinary tract dilatation (UTD) was designed to be more objective and reproducible than previously used systems. We sought to evaluate interobserver reliability of UTD components and overall scores in a prenatal population undergoing third-trimester ultrasound examinations. METHODS: We retrospectively identified patients who underwent antenatal ultrasound examinations for UTD between 28 and 40 weeks' gestation. All images from individual studies of 300 fetuses were reviewed independently by 5 experienced sonologists (1 maternal-fetal medicine specialist and 4 radiologists). Urinary tract dilatation scores (normal, A1, or A2/3) and Society for Fetal Urology (SFU) scores were assigned. Interobserver agreement between raters was evaluated with the Fleiss κ statistic. RESULTS: Overall interobserver agreement for the antenatal UTD risk score showed substantial agreement among all 5 readers (κ = 0.657 [95% confidence interval, 0.632, 0.683]; P < .001). All 5 readers applied the same UTD risk score in 53.7% of cases. Some variability in the antenatal UTD score and individual elements was observed. At least 2 UTD risk scores were assigned to a specific individual patient in 46.3% of cases (139 of 300), and all 3 UTD risk scores were assigned to a specific individual patient in 1.7% of cases (5 of 300). In 18.0% of cases (54 of 300), at least 2 readers assigned a UTD score different from that assigned by the other readers. Agreement was lowest for parenchymal appearance (κ = 0.225). Agreement for the SFU system was fair (κ = 0.368; P < .001). CONCLUSIONS: Interobserver agreement for the antenatal UTD grading system was substantial. Compared to the SFU system, the antenatal UTD system showed better agreement among readers.

Prenatal diagnosis of renal duplication by magnetic resonance imaging.

Purpose: To determine the value of fetal magnetic resonance imaging (MRI) to detect renal duplication.Methods: In this retrospective study, prenatal MRI and ultrasound (US) diagnoses were compared with postnatal imaging and/or surgical data. Twenty-six pregnant women (average age, 32 years; range, 29-36 years) underwent MRI at a mean gestational age of 25 weeks (range, 21-33 weeks). MRI was performed with a 1.5-T unit within 1 week after prenatal ultrasound examination. The steady-state free-precession (SSFP), single-shot turbo spin echo (SSTSE), and T1-weighted fast imaging sequences were used.Results: Twenty-four cases of fetal renal duplications diagnosed using prenatal MRI were judged to be correct when compared with postnatal imaging and surgical follow-up. In 18 of 26 cases, the diagnoses established using prenatal US were correct when compared with postnatal diagnosis. In 2 of 26 cases, the diagnosis with both prenatal US and MRI were not entirely correct when compared with postnatal diagnosis. In the two cases, magnetic resonance (MR) identified left two pelvicalyceal systems but could not found ipsilateral ectopic ureteral orifice, US only found left hydronephrosis but could not found duplex collection system. In other six cases, MR corrected the US diagnosis by providing a more accurate renal morphology or additional diagnostic information.Conclusions: MRI is an effective method for the diagnosis of fetal duplex kidney deformity and associated ureteral and other abnormalities.

The perineal midsagittal view in male fetuses - pivotal for assessing genitourinary disorders.

A wide range of genitourinary pathologies can be diagnosed in utero, from a simple vesicoureteral reflux to a more complex disorder of sexual differentiation. The prognosis and neonatal management of these conditions differ significantly. Evaluation of the fetal perineal anatomy is paramount to making the right diagnosis. The aim of this pictorial essay is to show sonographers how to acquire a perineal midsagittal view in a male fetus, and to demonstrate how this specific view allows assessment of the urethra and penis, to differentiate various genitourinary pathologies.

Histology Atlas of the Developing Mouse Urinary System With Emphasis on Prenatal Days E10.5-E18.5.

Congenital abnormalities of the urinary tract are some of the most common human developmental abnormalities. Several genetically engineered mouse models have been developed to mimic these abnormalities and aim to better understand the molecular mechanisms of disease. This atlas has been developed as an aid to pathologists and other biomedical scientists for identification of abnormalities in the developing murine urinary tract by cataloguing normal structures at each stage of development. Hematoxylin and eosin- and immunohistochemical-stained sections are provided, with a focus on E10.5-E18.5, as well as a brief discussion of postnatal events in urinary tract development. A section on abnormalities in the development of the urinary tract is also provided, and molecular mechanisms are presented as supplementary material. Additionally, overviews of the 2 key processes of kidney development, branching morphogenesis and nephrogenesis, are provided to aid in the understanding of the complex organogenesis of the kidney. One of the key findings of this atlas is the histological identification of the ureteric bud at E10.5, as previous literature has provided conflicting reports on the initial point of budding. Furthermore, attention is paid to points where murine development is significantly distinct from human development, namely, in the cessation of nephrogenesis.

Sprouty1 Controls Genitourinary Development via its N-Terminal Tyrosine.

BACKGROUND: Studies in mice suggest that perturbations of the GDNF-Ret signaling pathway are a major genetic cause of congenital anomalies of the kidney and urinary tract (CAKUT). Mutations in Sprouty1, an intracellular Ret inhibitor, results in supernumerary kidneys, megaureters, and hydronephrosis in mice. But the underlying molecular mechanisms involved and which structural domains are essential for Sprouty1 function are a matter of controversy, partly because studies have so far relied on ectopic overexpression of the gene in cell lines. A conserved N-terminal tyrosine has been frequently, but not always, identified as critical for the function of Sprouty1 in vitro. METHODS: We generated Sprouty1 knockin mice bearing a tyrosine-to-alanine substitution in position 53, corresponding to the conserved N-terminal tyrosine of Sprouty1. We characterized the development of the genitourinary systems in these mice via different methods, including the use of reporter mice expressing EGFP from the Ret locus, and whole-mount cytokeratin staining. RESULTS: Mice lacking this tyrosine grow ectopic ureteric buds that will ultimately form supernumerary kidneys, a phenotype indistinguishable to that of Sprouty1 knockout mice. Sprouty1 knockin mice also present megaureters and vesicoureteral reflux, caused by failure of ureters to separate from Wolffian ducts and migrate to their definitive position. CONCLUSIONS: Tyrosine 53 is absolutely necessary for Sprouty1 function during genitourinary development in mice.

DYRK1A-related intellectual disability: a syndrome associated with congenital anomalies of the kidney and urinary tract.

PURPOSE: Haploinsufficiency of DYRK1A causes a recognizable clinical syndrome. The goal of this paper is to investigate congenital anomalies of the kidney and urinary tract (CAKUT) and genital defects (GD) in patients with DYRK1A variants. METHODS: A large database of clinical exome sequencing (ES) was queried for de novo DYRK1A variants and CAKUT/GD phenotypes were characterized. Xenopus laevis (frog) was chosen as a model organism to assess Dyrk1a's role in renal development. RESULTS: Phenotypic details and variants of 19 patients were compiled after an initial observation that one patient with a de novo pathogenic variant in DYRK1A had GD. CAKUT/GD data were available from 15 patients, 11 of whom presented with CAKUT/GD. Studies in Xenopus embryos demonstrated that knockdown of Dyrk1a, which is expressed in forming nephrons, disrupts the development of segments of embryonic nephrons, which ultimately give rise to the entire genitourinary (GU) tract. These defects could be rescued by coinjecting wild-type human DYRK1A RNA, but not with DYRK1AR205* or DYRK1AL245R RNA. CONCLUSION: Evidence supports routine GU screening of all individuals with de novo DYRK1A pathogenic variants to ensure optimized clinical management. Collectively, the reported clinical data and loss-of-function studies in Xenopus substantiate a novel role for DYRK1A in GU development.

Applicability of Magnetic Resonance Imaging in the Assessment of Fetal Urinary Tract Malformations.

OBJECTIVE: To assess the applicability of magnetic resonance imaging (MRI) to complement ultrasound in the diagnosis of fetal urinary tract anomalies. METHODS: This was a retrospective cohort study that included 41 women between 19 weeks and 37 weeks and 6 days of gestation carrying fetuses with malformations of the urinary tract which were initially diagnosed by ultrasound and then referred for MRI. In all cases, the diagnosis was confirmed after birth either through imaging or autopsy. A surface coil was positioned over the abdomen and T2-weighted sequences were obtained in the axial, coronal, and sagittal planes; T1 in at least one plane; and three-dimensional (3-D) TRUFI in fetuses with dilatation of the urinary tract. RESULTS: Mean gestational age at the time of MRI examination was 28.21 weeks. The rapid T2 sequences allowed all the anomalies of the fetal urinary tract to be assessed, whereas 3-D TRUFI sequencing proved very useful in evaluating anomalies involving dilatation of the urinary tract. The signs of pulmonary hypoplasia characterized by hypointense signal in the T2-weighted sequences were identified in 13 of the 41 fetuses. CONCLUSION: MRI confirmed and added information to the ultrasound regarding fetal urinary tract anomalies, as well as information related to the other associated malformations, their progress in the prenatal period, and possible postnatal prognosis.

Prenatal Urinary Tract Dilatation.

Urinary tract dilatation (UTD) is the most common congenital anomaly detected on prenatal ultrasonography (US), affecting 1% to 3% of all pregnancies. This article focuses on the prenatal detection of UTD and the postnatal evaluation and management based on the UTD grading system risk assessment. Prophylactic antibiotics and postnatal imaging are discussed. The recent management trend is for a more conservative approach to minimize unnecessary testing and exposures to the fetus and neonate while detecting those who may have clinically significant disorder. The renal bladder US remains a critical part of the evaluation and helps guide further investigations.

Perinatal Outcomes of Fetal Lower Urinary Tract Obstruction After Vesicoamniotic Shunting Using a Double-Basket Catheter.

OBJECTIVES: To evaluate the perinatal survival and renal function of fetuses with lower urinary tract obstruction (LUTO) who underwent vesicoamniotic shunting using a double-basket catheter METHODS: We retrospectively reviewed 32 fetuses with LUTO who underwent vesicoamniotic shunting using a double-basket catheter between 1998 and 2013. RESULTS: Among the 32 fetuses examined, 5 died because of termination of pregnancy, and 2 died in utero. The median gestational age at diagnosis was 15.5 (range, 10.0-27.3) weeks, and that at initial shunting was 17.1 (range, 12.3-32.2) weeks. Shunt dislocation or occlusion occurred in 18 of 42 procedures (42.8%). The median gestational age at delivery for the 25 live births was 35.5 (range, 28-40) weeks. Postnatal diagnosis revealed posterior urethral valves in 15 fetuses, a cloacal anomaly in 7, and urethral stenosis in 3. Three neonatal deaths occurred, resulting in an overall perinatal survival rate of 68.8% (22 of 32). The rates of normal renal function were 40.6% (13 of 32) at 28 days and 40% (10 of 25) at 2 years after birth. The absence of oligohydramnios after shunting was the only prognostic factor for normal renal function at 2 years (P < .05). CONCLUSIONS: Vesicoamniotic shunting may be helpful for fetuses with LUTO.

Loss of VAMP5 in mice results in duplication of the ureter and insufficient expansion of the lung.

BACKGROUND: Vesicle-associated membrane protein 5 (VAMP5) is a member of the SNARE protein family, which regulates the docking and fusion of membrane vesicles within cells. Previously, we reported ubiquitous expression of VAMP5 proteins in various organs except the brain and small intestine. However, the precise roles of VAMP5 in each organ remain unclear. To explore the roles of VAMP5 in vivo, we generated VAMP5 knockout (KO) mice. RESULTS: VAMP5 KO mice showed low birth rate and low body weight. KO embryos grew normally in the uterus, and tended to die around birth. Anatomical analysis revealed that viable KO mice often exhibited duplication of the ureter, and dead KO mice showed insufficient expansion of the lung. VAMP5 was localized in the epithelial cells of the ureter and terminal bronchiole. CONCLUSIONS: VAMP5 KO mice showed a low birth rate and abnormalities of the urinary and respiratory systems. VAMP5 KO mice died around birth, possibly due to defects in vesicoureteral flow and breathing. The results presented could provide a basis for future studies to understand the roles of VAMP5 protein. Developmental Dynamics 247:754-762, 2018. © 2018 Wiley Periodicals, Inc.

Aquaporin expression in the fetal porcine urinary tract changes during gestation.

The expression of aquaporins (AQPs) in the fetal porcine urinary tract and its relation to gestational age has not been established. Tissue samples from the renal pelvis, ureter, bladder and urethra were obtained from porcine fetuses. Samples were examined by RT-PCR (AQPs 1-11), QPCR (AQPs positive on RT-PCR), and immunohistochemistry. Bladder samples were additionally examined by Western blotting. RNA was extracted from 76 tissue samples obtained from 19 fetuses. Gestational age was 60 (n=11) or 100 days (n=8). PCR showed that AQP1, 3, 9 and 11 mRNA was expressed in all locations. The expression of AQP3 increased significantly at all four locations with gestational age, whereas AQP11 significantly decreased. AQP1 expression increased in the ureter, bladder and urethra. AQP9 mRNA expression increased in the urethra and bladder, but decreased in the ureter. AQP5 was expressed only in the urethra. Immunohistochemistry showed AQP1 staining in sub-urothelial vessels at all locations. Western blotting analysis confirmed increased AQP1 protein levels in bladder samples during gestation. Expression levels of AQP1, 3, 5, 9 and 11 in the urinary tract change during gestation, and further studies are needed to provide insights into normal and pathophysiological water handling mechanisms in the fetus.

Novel Insights into the Pathogenesis of Monogenic Congenital Anomalies of the Kidney and Urinary Tract.

Congenital anomalies of the kidneys and urinary tract (CAKUT) comprise a large spectrum of congenital malformations ranging from severe manifestations, such as renal agenesis, to potentially milder conditions, such as vesicoureteral reflux. CAKUT causes approximately 40% of ESRD that manifests within the first three decades of life. Several lines of evidence indicate that CAKUT is often caused by recessive or dominant mutations in single (monogenic) genes. To date, approximately 40 monogenic genes are known to cause CAKUT if mutated, explaining 5%-20% of patients. However, hundreds of different monogenic CAKUT genes probably exist. The discovery of novel CAKUT-causing genes remains challenging because of this pronounced heterogeneity, variable expressivity, and incomplete penetrance. We here give an overview of known genetic causes for human CAKUT and shed light on distinct renal morphogenetic pathways that were identified as relevant for CAKUT in mice and humans.

The duplicated collecting system of the urinary tract: embryology, imaging appearances and clinical considerations.

Duplication anomalies of the urinary collecting system are common and can be discovered and characterized with multiple imaging modalities. The embryology, imaging manifestations and clinical ramifications of duplicated ureters and renal collecting systems vary from a normal anatomical variant to urological pathology and are discussed and illustrated in this review.

Genetics of vesicoureteral reflux and congenital anomalies of the kidney and urinary tract.

The definition of congenital anomalies of the kidney and urinary tract (CAKUT) is the disease of structural malformations in the kidney and/or urinary tract containing vesicoureteral reflux (VUR). These anomalies can cause pediatric chronic kidney disease. However, the pathogenesis of CAKUT is not well understood, because identifying the genetic architecture of CAKUT is difficult due to the phenotypic heterogeneity and multifactorial genetic penetrance. We describe the current genetic basis and mechanisms of CAKUT including VUR via approaching the steps and signaling pathways of kidney developmental processes. We also focus on the newly developed strategies and challenges to fully address the role of the associated genes in the pathogenesis of the disease.

[Ultrasound of the fetal urinary system during the first trimester of pregnancy]. / Échographie de l'appareil urinaire fœtal au 1er trimestre de la grossesse.

The detection of abnormalities of the fetal urinary system in the first trimester of pregnancy is constantly improving, namely owing to the improved resolution of the image, the use of the endovaginal approach and thanks to sonographers' constant training. The pathological aspects, usually detected in the second trimester of pregnancy, can be suspected early in the first trimester and range from kidneys' cavity dilation to bilateral renal agenesis, polycystic kidney disease, multi-cystic dysplasia and bladder megavessia or bladder exstrophy. A poly-malformative syndrome is to be found out. The detection of an abnormality of the urinary tract requires a close ultrasound check. Very often, the pathological aspects tend to disappear spontaneously. In particular, the non-visualization of the bladder requires repeated examinations during the same session or even a little later in the pregnancy. We will carry out a review of the literature by pointing out the usual and unusual aspects of the fetal urinary system visible in the first trimester and we will as well propose an algorithm describing how to deal with abnormalities of the urinary tract that can be found out at first trimester ultrasound.