Noninvasive assessment of antenatal hydronephrosis in mice reveals a critical role for Robo2 in maintaining anti-reflux mechanism

Antenatal hydronephrosis and vesicoureteral reflux (VUR) are common renal tract birth defects. We recently showed that disruption of the Robo2 gene is associated with VUR in humans and antenatal hydronephrosis in knockout mice. However, the natural history, causal relationship and developmental origins of these clinical conditions remain largely unclear. Although the hydronephrosis phenotype in Robo2 knockout mice has been attributed to the coexistence of ureteral reflux and obstruction in the same mice, this hypothesis has not been tested experimentally. Here we used noninvasive high-resolution micro-ultrasonography and pathological analysis to follow the progression of antenatal hydronephrosis in individual Robo2-deficient mice from embryo to adulthood. We found that hydronephrosis progressed continuously after birth with no spontaneous resolution. With the use of a microbubble ultrasound contrast agent and ultrasound-guided percutaneous aspiration, we demonstrated that antenatal hydronephrosis in Robo2-deficient mice is caused by high-grade VUR resulting from a dilated and incompetent ureterovesical junction rather than ureteral obstruction. We further documented Robo2 expression around the developing ureterovesical junction and identified early dilatation of ureteral orifice structures as a potential fetal origin of antenatal hydronephrosis and VUR. Our results thus demonstrate that Robo2 is crucial for the formation of a normal ureteral orifice and for the maintenance of an effective anti-reflux mechanism. This study also establishes a reproducible genetic mouse model of progressive antenatal hydronephrosis and primary high-grade VUR.     

输尿管子宫内膜异位症伴肾积水1 例报告并文献复习

目的:探讨子宫内膜异位症累及输尿管的诊断和治疗方法。方法:术前诊断为右侧输尿管下段占位病变伴右肾积水的42岁女性患者,行下腹正中切口,探查右侧输尿管开口处可见淡黄色息肉样病变,突入膀胱,输尿管下段增粗并全程扩张积水,行输尿管下段并膀胱袖式切除,输尿管膀胱再植术。术后病理报告为输尿管子宫内膜异位症。结果:术后复查B超示右肾积水较术前恢复,术后予抑那通3.75mg/28d,随访6个月未见复发。结论:对于输尿管占位并上尿路积水的女性患者,除考虑肿瘤外还应考虑子宫内膜异位症可能。手术联合内分泌治疗是治疗输尿管子宫内膜异位伴肾积水的有效方法。     

Incomplete protection mechanism against vesico-ureteral reflux and hydronephrosis in the inbred mouse strain DDD

We have previously reported the occurrence and inheritance mode of hydronephrosis in the inbred mouse strain DDD. The present investigation examined the possibility that hydronephrosis may be caused by a vesico-ureteral reflux (VUR). Bladder pressure was measured under anaesthesia in 3 strains of mice (DDD, ddY and C57BL/6). VUR was demonstrated by lower bladder pressure only in the DDD strain. Loading pressure into the renal pelvis (LPP) was significantly higher in DDD than in C57BL/6 (P less than 0.001). Correlations between LPP and severity of hydronephrosis were significantly positive in DDD and ddY, indicating that mice showing higher LPPs had the severest disease. Scanning electron micrography revealed that the ureteral orifice of DDD (100-300 microns) was much larger than in C57BL/6 (30 microns), and thus offered scant protection against VUR in DDD. These results suggest that DDD hydronephrosis caused by VUR is related primarily to the absence of an adequate protection mechanism in the ureteral orifice.     

Perfusion Index Derived from a Pulse Oximeter Can Detect Changes in Peripheral Microcirculation during Uretero-Renal-Scopy Stone Manipulation (URS-SM)

Background

The objective of this study was to test the effect of removal of a ureteral obstruction (renal calculus) from anesthetized patients on the perfusion index (PI), as measured by a pulse oximeter, and on the estimated glomerular filtration rate (eGFR).

Patients and Methods

This prospective study enrolled 113 patients with unilateral ureteral obstructions (kidney stones) who were scheduled for ureteroscopy (URS) laser lithotripsy. One urologist graded patient hydronephrosis before surgery. A pulse oximeter was affixed to each patient''s index finger ipsilateral to the intravenous catheter, and a non-invasive blood pressure cuff was placed on the contralateral side. Ipsilateral double J stents and Foley catheters were inserted and left indwelling for 24 h. PI and mean arterial pressure (MAP) were determined at baseline, 5 min after anesthesia, and 10 min after surgery; eGFR was determined at admission, 1 day after surgery, and 14 days after surgery.

Results

Patients with different grades of hydronephrosis had similar age, eGFR, PI, mean arterial pressure (MAP), and heart rate (HR). PI increased significantly in each hydronephrosis group after ureteral stone disintegration. None of the groups had significant post-URS changes in eGFR, although eGFR increased in the grade I hydronephrosis group after 14 days. The percent change of PI correlates significantly with the percent change of MAP, but not with that of eGFR.

Conclusion

Our results demonstrate that release of a ureteral obstruction leads to a concurrent increase of PI during anesthesia. Measurement of PI may be a valuable tool to monitor the successful release of ureteral obstructions and changes of microcirculation during surgery. There were also increases in eGFR after 14 days, but not immediately after surgery.     

Frequency of hydronephrosis in Wistar rats

Kidneys from 1806 Wistar rats were examined grossly for hydronephrosis and ureteral dilation. Hydronephrosis was seen more often on the right side (11%) than the left (0.3%). Overall frequency of hydronephrosis in males (181/1305) was greater than in females (23/501), and the frequency was statistically greater in male rats aged 5,6,8 and 9 weeks than in age-matched females.     

Deep infiltrating ureteral endometriosis with catamenial hydroureteronephrosis: a case report

Background

This aim of this case report is to raise awareness of ureteral endometriosis in women of reproductive age with hydronephrosis in the absence of urolithiasis to enable early diagnosis and prevent loss of renal function.

Case presentation

A 44-year-old Asian woman presented with a 4-year history of cyclic right flank pain and right hydronephrosis during menstruation. Despite several evaluations by physicians, including gynecologists, the cause of her symptoms was not diagnosed. On transvaginal ultrasonography, the uterus was observed deviated to the right, with a nodular lesion at the right uterosacral ligament, and the right ovary was attached to the uterus with no apparent cystic lesion. Magnetic resonance imaging showed a mass in the right uterine wall and mild wall thickening with delayed enhancement of the right distal ureter. Right ureteral endometriosis was suspected. Diagnostic laparoscopy revealed narrowing of the distal right ureter between the right uterosacral ligament and the right ovary with adhesions caused by deep infiltrating endometriosis. The adhesion bands and infiltrating endometriosis around the right ureter were dissected.

Conclusions

The nonspecific symptoms of ureteral endometriosis can result in incorrect diagnosis, with renal damage as a result of prolonged hydronephrosis. A high index of suspicion and use of imaging modalities enable earlier diagnosis and preservation of renal function.

     

Repression of apurinic/apyrimidinic endonuclease by p53-dependent apoptosis in hydronephrosis-induced rat kidney

p53 plays a major role in apoptosis through activation of pro-apoptotic gene Bax. It also regulates apurinic/apyrimidinic endonuclease (APE) expression in the base excision repair pathway against oxidative DNA damages. This study investigated whether p53-dependent apoptosis is correlated with APE using an experimental rat model of hydronephrosis. Hydronephrosis was induced by partial ligation of the right ureter. Animals were sacrificed on scheduled time after unilateral ureteral obstruction and the expression of 8-OHdG, γ-H2AX, apoptotic proteins and APE was determined. The accumulated p53 activated Bax and caspase-3 7 days after hydronephrosis induction and the resulting high levels of p53-dependent apoptotic proteins and γ-H2AX tended to decrease APE. The intensities of 8-OHdG and caspase-3 immunolocalization significantly increased in obstructed kidneys than in sham-operated kidneys, although APE immunoreactivity increased after hydronephrosis induction. These results suggest that oxidative DNA damages in obstructed kidneys may trigger p53-dependent apoptosis through repression of APE.     

胎羊单侧输尿管梗阻模型的建立

目的建立胎羊单侧输尿管梗阻的动物模型,探讨其病理、影像学特点。方法取12只单胎妊娠75-85 d的健康山羊,采用宫内手术的方法造成胎羊左侧输尿管不完全梗阻。对羔羊进行影像、病理学研究。结果12只孕羊中有3只流产;有9只孕羊顺产羔羊。超声检查：梗阻后的第3周内胎羊左肾显著增大、积水及实质变薄。放射学检查：羔羊左肾积水并且功能受损害。病理学检查：左肾肾小球数目减少,肾小管扩张明显,未见肾发育不良。结论对山羊单胎妊娠中期胎羊进行宫内手术建立胎羊单侧输尿管梗阻的动物模型是可行的,该模型能很好地模拟肾盂输尿管连接部梗阻所致的胎儿肾积水。     

Repression of apurinic/apyrimidinic endonuclease by p53-dependent apoptosis in hydronephrosis-induced rat kidney

Abstract

p53 plays a major role in apoptosis through activation of pro-apoptotic gene Bax. It also regulates apurinic/apyrimidinic endonuclease (APE) expression in the base excision repair pathway against oxidative DNA damages. This study investigated whether p53-dependent apoptosis is correlated with APE using an experimental rat model of hydronephrosis. Hydronephrosis was induced by partial ligation of the right ureter. Animals were sacrificed on scheduled time after unilateral ureteral obstruction and the expression of 8-OHdG, γ-H2AX, apoptotic proteins and APE was determined. The accumulated p53 activated Bax and caspase-3 7 days after hydronephrosis induction and the resulting high levels of p53-dependent apoptotic proteins and γ-H2AX tended to decrease APE. The intensities of 8-OHdG and caspase-3 immunolocalization significantly increased in obstructed kidneys than in sham-operated kidneys, although APE immunoreactivity increased after hydronephrosis induction. These results suggest that oxidative DNA damages in obstructed kidneys may trigger p53-dependent apoptosis through repression of APE.     

Pathogenesis of ethanol-induced hydronephrosis and hydroureter as demonstrated following in vivo exposure of mouse embryos

Urinary tract abnormalities have been noted to occur in 10-27% of individuals diagnosed as having Fetal Alcohol Syndrome. Among a wide range of functional and structural abnormalities, renal agenesis/hypoplasia, hydronephrosis, and ureteropelvic obstruction feature most prominently. This study was designed to examine the pathogenesis of ethanol-induced urinary tract abnormalities in a mouse model. C57Bl/6J mice were acutely exposed to two doses of ethanol (2.9 g/kg IP) administered 4 hours apart beginning on gestational day (GD) 9, hour 4. This resulted in an incidence of 40.7% urinary tract anomalies among GD18 fetuses. With the exception of duplicate ureter, urinary tract abnormalities consisted exclusively of hydroureter/hydronephrosis. Examination of GD13-17 fetuses revealed that the first grossly detectable differences in the urinary tracts of control vs. affected specimens occurred on GD16 and initially only involved ureteral changes. Hydronephrosis was first detected on GD17. A contributing factor to the development of hydronephrosis appears to be the abnormal location of the ureterovesicle junction which commonly involves duplicate ureteral lumens with resultant functional obstruction to urine flow at the distal end of the ureter. Study of the early pathogenetic changes which appear to result in the urinary tract malformations observed involved utilization of scanning electron microscopy, vital dye (Nile blue sulphate) staining of whole embryos, and analysis of histological sections. These studies revealed that 12 hours following initial maternal ethanol exposure, embryos have excessive amounts of cell death localized in the region of the developing mesonephric duct just proximal to the cloaca. Also affected were premigratory neural crest cells located just proximal to the posterior neuropore. We conclude that excessive amounts of ethanol-induced cell death in these selectively vulnerable populations could account for the subsequently observed urinary tract malformations.     

Molecular pathology of murine ureteritis causing obstructive uropathy with hydronephrosis

Primary causes of urinary tract obstruction that induces urine retention and results in hydronephrosis include uroliths, inflammation, and tumors. In this study, we analyzed the molecular pathology of ureteritis causing hydronephrosis in laboratory rodents.F2 progenies of C57BL/6 and DBA/2 mice were studied histopathologically and by comprehensive gene expression analysis of their ureters. Incidence of hydronephrosis was approximately 5% in F2 progenies. Histopathologically, this hydronephrosis was caused by stenosis of the proximal ureter, which showed fibrosis and papillary malformations of the proliferative epithelium with infiltrations of B-cell-dominated lymphocytes. Additionally, CD16-positive large granular leukocytes and eosinophils infiltrated from the ureteral mucosa to the muscular layer. Eosinophilic crystals were characteristically observed in the lumen of the ureter and the cytoplasm of large granular leukocytes, eosinophils, and transitional epithelial cells. Comprehensive gene profiling revealed remarkably elevated expression of genes associated with hyperimmune responses through activation of B cells in diseased ureters. Furthermore, diseased ureters showed dramatically higher gene expression of chitinase 3-like 3, known as Ym1, which is associated with formation both of adenomas in the transitional epithelium and of eosinophilic crystals in inflammatory conditions. The Ym1 protein was mainly localized to the cytoplasm of the transitional epithelium, infiltrated cells, and eosinophilic crystals in diseased ureters.We determined that the primary cause of hydronephrosis in F2 mice was ureteritis mediated by the local hyperimmune response with malformation of the transitional epithelium. Our data provide a novel molecular pathogenesis for elucidating causes of aseptic inflammation in human upper urinary tracts.     

Smad4 Regulates Ureteral Smooth Muscle Cell Differentiation during Mouse Embryogenesis

Proper formation of ureteral smooth muscle cells (SMCs) during embryogenesis is essential for ureter peristalsis that propels urine from the kidney to the bladder in mammals. Currently the molecular factors that regulate differentiation of ureteral mesenchymal cells into SMCs are incompletely understood. A recent study has reported that Smad4 deficiency reduces the number of ureteral SMCs. However, its precise role in the ureteral smooth muscle development remains largely unknown. Here, we used Tbx18:Cre knock-in mouse line to delete Smad4 to examine its requirement in the development of ureteral mesenchyme and SMC differentiation. We found that mice with specific deletion of Smad4 in Tbx18-expressing ureteral mesenchyme exhibited hydroureter and hydronephrosis at embryonic day (E) 16.5, and the mutant mesenchymal cells failed to differentiate into SMCs with increased apoptosis and decreased proliferation. Molecular markers for SMCs including alpha smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SM-MHC) were absent in the mutant ureters. Moreover, disruption of Smad4 significantly reduced the expression of genes, including Sox9, Tbx18 and Myocardin associated with SMC differentiation. These findings suggest that Smad4 is essential for initiating the SMC differentiation program during ureter development.     

基因谱系示踪揭示小鼠Tbx18+肾脏间质祖细胞分化为输尿管平滑肌

本文旨在研究Tbx18+肾脏间质祖细胞分化为输尿管平滑肌细胞的命运及转录因子Tbx18在小鼠输尿管平滑肌发育形成中起到的作用．实验建立Tbx18:Cre/R26REYFP和Tbx18:Cre/R26RLacZ两种谱系示踪系统和Tbx18:Cre/Cre 敲除模型．该示踪模型通过cre重组酶的表达能有效地示踪Tbx18+肾脏间质祖细胞在泌尿系统的发育命运．通过免疫荧光染色和X-gal染色,同时发现Tbx18+肾脏间质祖细胞可分化为输尿管平滑肌细胞,但不分化为输尿管移行上皮细胞．在Tbx18:Cre/Cre基因突变模型中,泌尿系统出现明显的肾积水和输尿管积水,肾盏、肾盂扩张,输尿管明显缩短和扩张．实验结果揭示,Tbx18+ 肾脏间质祖细胞可以分化为输尿管平滑肌细胞,且转录因子Tbx18在哺乳动物输尿管平滑肌的发育中起到重要的作用．     

Feasibility and safety of cryoablation on the porcine ureter using a new balloon cryoprobe

Cryoablation, as a well-characterized technology, has multifarious clinical applications. But few are reported on ureteral endometriosis. Thus, we examined the feasibility and safety of cryotherapy with a novel balloon cryoprobe on ureter in a live porcine model. During the freezing and thawing cycle, temperature was recorded in different parts of the ureter in real-time. Two-minute cryoablation could induce necrosis within range in 1 cm diameter on serosa layer. The temperature respectively dropped to −136.5 °C, −96.1 °C and −17.5 °C at the cryotherapy center, 1 cm and 1.5 cm from center on serosal side. The ureters were harvested immediately, 2 weeks or 3 months after cryotherapy. No perforation, stricture, adhesions, or hydronephrosis was observed. Histopathologic representations of ureters after cryoablation indicated that full thickness necroses of ureters were seen in all samples. The results demonstrated ureteral cryoablation using a novel balloon probe was feasible, safe, and effective. These findings provided us reference before cryoablation could be applied in clinical practice in treating ureteral endometriosis.     

GSDME-mediated pyroptosis promotes inflammation and fibrosis in obstructive nephropathy

Renal tubular cell (RTC) death and inflammation contribute to the progression of obstructive nephropathy, but its underlying mechanisms have not been fully elucidated. Here, we showed that Gasdermin E (GSDME) expression level and GSDME-N domain generation determined the RTC fate response to TNFα under the condition of oxygen-glucose-serum deprivation. Deletion of Caspase-3 (Casp3) or Gsdme alleviated renal tubule damage and inflammation and finally prevented the development of hydronephrosis and kidney fibrosis after ureteral obstruction. Using bone marrow transplantation and cell type-specific Casp3 knockout mice, we demonstrated that Casp3/GSDME-mediated pyroptosis in renal parenchymal cells, but not in hematopoietic cells, played predominant roles in this process. We further showed that HMGB1 released from pyroptotic RTCs amplified inflammatory responses, which critically contributed to renal fibrogenesis. Specific deletion of Hmgb1 in RTCs alleviated caspase11 and IL-1β activation in macrophages. Collectively, our results uncovered that TNFα/Casp3/GSDME-mediated pyroptosis is responsible for the initiation of ureteral obstruction-induced renal tubule injury, which subsequentially contributes to the late-stage progression of hydronephrosis, inflammation, and fibrosis. This novel mechanism will provide valuable therapeutic insights for the treatment of obstructive nephropathy.Subject terms: Cell death and immune response, Kidney diseases     

Bone marrow mesenchymal stem cells reduce ureteral stricture formation in a rat model via the paracrine effect of extracellular vesicles

With no effective therapy to prevent or treat ureteral stricture (US), a multifactorial fibrotic disease after iatrogenic injury of the ureter, the need for new therapies is urgent. Mesenchymal stem cells (MSCs) have been widely studied for treating tissue defects and excessive fibrosis, and recent studies established that one of the main therapeutic vectors of MSCs is comprised in their secretome and represented by extracellular vesicles (EVs). Thus, we have determined to explore the specific role of MSCs‐derived EVs (MSC‐EVs) treatment in a pre‐clinical model of US. The results firstly showed that either a bolus dose of MSCs or a bolus dose of MSC‐EVs (administration via renal‐arterial) significantly ameliorated ureteral fibrosis and recuperated ureter morphological development in a US rat model. We confirmed our observations through MSCs or MSC‐EVs treatment alleviated hydronephrosis, less renal dysfunction and blunted transforming growth factor‐β1 induced fibration. Due to MSC‐EVs are the equivalent dose of MSCs, and similar curative effects of transplantation of MSCs and MSC‐EVs were observed, we speculated the curative effect of MSCs in treating US might on account of the release of EVs through paracrine mechanisms. Our study demonstrated an innovative strategy to counteract ureteral stricture formation in a rat model of US.     

Malignant Ureteral Obstruction: Functional Duration of Metallic versus Polymeric Ureteral Stents

Background

Ureteral obstruction caused by extrinsic compression is often associated with intra-abdominal cancers. Internal drainage with ureteral stents is typically the first-line therapy to relieve such obstructions. Novel designs of ureteral stents made of different materials have been invented to achieve better drainage. In this study, we described the functional outcomes of a Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) in patients with malignant ureteral obstruction and compare the functional duration of Resonance stents with regular polymeric stents in the same cohort.

Methods

Cancer patients who received polymeric stents and subsequent Resonance stents for ureteral obstruction between July 2009 and November 2012 were included in a chart review. Stent failure was detected by clinical symptoms, imaging studies, and renal function tests. The functional durations of each stent were calculated, and possible factors affecting stent patency were investigated.

Results

A total of 50 stents were successfully inserted into 50 ureteral units in 42 patients with malignant ureteral obstruction. There were 7 antegrade stents and 43 retrograde stents. There were no major complications. Stent-related symptoms were similar in both kinds of stents. After polymeric stents were replaced with Resonance metallic stents, hydronephrosis subsided or remained stable in 90% (45/50) of the ureteral units. Serum creatinine decreased or remained stable in 90% (38/42) of these patients. The Resonance stent exhibited a mean increase in functional duration of 4 months compared with the polymeric stents (p<0.0001), and 50% (25/50) of the Resonance stents exhibited a significant increase in functional duration (more than 3 months). Pre-operative serum creatinine < 2 was associated with a substantial increase in stent duration.

Conclusions

Resonance stents are effective and safe in relieving malignant ureteral obstructions after polymeric stents failure. Resonance stents can provide a longer functional duration than polymeric stents and should be offered as an option for internal drainage.     

An immunoelectron-microscopical observation of mouse juxtaglomerular cells in the case of experimental hydronephrosis.

Changes in juxtaglomerular (JG; renin-containing) cells in experimental hydronephrosis 1 month after ureteral ligation were investigated with immunoelectron-microscopical techniques. Two types of granules, electron dense (D) and lucent (L), were observed. D type granules were labeled more intensely with gold particles than those of L type. Granules intermediate between D and L types and exocytosis of D types were observed. In the cells containing D types exclusively, gold particles were restricted to the granules, whereas in the cells containing both D and L type granules, the particles were scattered throughout the cytoplasmic cytosol. The authors discuss the mechanisms of renin release in JG cells.     

Management of vesicoureteral reflux

Four cases of vesicoureteral reflux are discussed by prominent pediatric urologists. The condition can range from minimal reflux into the distal ureter to massive reflux causing tortuosity of the ureter and hydronephrosis. Treatment options range from medical management to tapering of the ureter with reimplantation. The cross-trigonal technique is popular among pediatric urologists, and the Politano-Leadbetter technique is a very successful technique that has stood the test of time. The extravesical approach to ureteral reimplantation reduces morbidity, shortens hospital stays, reduces medical costs, and maintains the high success rates of the intravesical techniques. Subureteric injection of bulking agents to correct the reflux holds promise as an alternative to open surgery, but presents the challenge of identifying the ideal bulking agent.     

Application of Ureteroscope in Emergency Treatment with Persistent Renal Colic Patients during Pregnancy

Background

Although the application of ureteroscopy in the treatment of ureteral calculi during pregnancy has been on the rise, for persistent renal colic patients without ultrasound-detected ureteral calculi, it may represent a clinical dilemma due to the potential risks for both mother and fetus.

Objective

The aim of the present study is to present our experience with the application of the ureteroscope in the emergency treatment of persistent renal colic patients during pregnancy.

Methods

From March 2009 to September 2014, a total of 117 pregnant women who received ureteroscopy for persistent renal colic were retrospectively analyzed. Patients were divided into three groups according to duration of the persistent renal colic: Group A (within 12 hours; 24 cases); Group B (12 to 24 hours; 76 cases); and Group C (more than 24 hours; 17 cases). The stone-free rate, complications, and other qualitative data were analyzed.

Results

Of the 117 patients, 31 patients who were found not to have renal or ureteral calculi received ureteroscopic double-J (DJ) stent insertion, whereas 86 patients who were found with ureteral calculi received ureteroscopic lithotripsy (URSL) and DJ stent insertion. Among them, 24 patients (27.9%) were found with ureteral calculi by ureteroscopy rather than ultrasound. In addition, 73 patients (84.9%) had complete fragmentation of calculi; 12 patients (10.3%) had a threatened abortion (the rates of threatened abortion in Groups A, B and C were 8.3% vs. 6.5% vs. 29.4%; Group C compared with Groups A and B, p<0.05), and one patient (1.2%) had urosepsis (in Group C). However, these complications were cured with conservative treatment, without postpartum infant and maternal complications.

Conclusion

For pregnant patients with persistent renal colic/ureteral calculi and hydronephrosis, ureteroscopic DJ stent insertion and URSL are effective and safe options when conservative treatment fails, even if no urinary calculi were found by ultrasound. At the same time, for patients with persistent renal colic during pregnancy, early application of ureteroscopy may reduce the risk of preterm birth.