Altered expression, but small contribution, of the histone demethylase KDM6A in obstructive uropathy in mice.

Epigenetic processes have emerged as important modulators of kidney health and disease. Here, we studied the role of KDM6A (a histone demethylase that escapes X-chromosome inactivation) in kidney tubule epithelial cells. We initially observed an increase in tubule cell Kdm6a mRNA in male mice with unilateral ureteral obstruction (UUO). However, tubule cell knockout of KDM6A had relatively minor consequences, characterized by a small reduction in apoptosis, increase in inflammation and downregulation of the peroxisome proliferator-activated receptor (PPAR) signaling pathway. In proximal tubule lineage HK-2 cells, KDM6A knockdown decreased PPARγ coactivator-1α (PGC-1α) protein levels and mRNA levels of the encoding gene, PPARGC1A. Tubule cell Kdm6a mRNA levels were approximately 2-fold higher in female mice than in male mice, both under sham and UUO conditions. However, kidney fibrosis after UUO was similar in both sexes. The findings demonstrate Kdm6a to be a dynamically regulated gene in the kidney tubule, varying in expression levels by sex and in response to injury. Despite the context-dependent variation in Kdm6a expression, knockout of tubule cell KDM6A has subtle (albeit non-negligible) effects in the adult kidney, at least in males.

Delayed onset of smooth muscle cell differentiation leads to hydroureter formation in mice with conditional loss of the zinc finger transcription factor gene Gata2 in the ureteric mesenchyme.

The establishment of the peristaltic machinery of the ureter is precisely controlled to cope with the onset of urine production in the fetal kidney. Retinoic acid (RA) has been identified as a signal that maintains the mesenchymal progenitors of the contractile smooth muscle cells (SMCs), while WNTs, SHH, and BMP4 induce their differentiation. How the activity of the underlying signalling pathways is controlled in time, space, and quantity to activate coordinately the SMC programme is poorly understood. Here, we provide evidence that the Zn-finger transcription factor GATA2 is involved in this crosstalk. In mice, Gata2 is expressed in the undifferentiated ureteric mesenchyme under control of RA signalling. Conditional deletion of Gata2 by a Tbx18cre driver results in hydroureter formation at birth, associated with a loss of differentiated SMCs. Analysis at earlier stages and in explant cultures revealed that SMC differentiation is not abrogated but delayed and that dilated ureters can partially regain peristaltic activity when relieved of urine pressure. Molecular analysis identified increased RA signalling as one factor contributing to the delay in SMC differentiation, possibly caused by reduced direct transcriptional activation of Cyp26a1, which encodes an RA-degrading enzyme. Our study identified GATA2 as a feedback inhibitor of RA signalling important for precise onset of ureteric SMC differentiation, and suggests that in a subset of cases of human congenital ureter dilatations, temporary relief of urine pressure may ameliorate the differentiation status of the SMC coat. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The role of HCN channels in peristaltic dysfunction in human ureteral tuberculosis.

OBJECTIVE: To explore the role of HCN channels in ureteral peristaltic dysfunction by comparing the changes in HCN channel levels between normal and tuberculous ureters. METHODS: A total of 32 specimens of human upper ureters were collected by nephrectomy from patients with renal tumor (control group, n = 16) or from patients with renal tuberculosis (experimental group, n = 16); the two groups did not receive radiotherapy, chemotherapy, immunotherapy, or any other special treatment before the surgical procedure. An experimental study on smooth muscle strips of human upper ureters showed variation in contraction amplitude and frequency after adding ZD7288, a specific blocker of HCN channels. The expression of HCN channels in the ureter was confirmed by Western blot (WB) and by confocal analysis of double immunostaining for c-kit and HCN channel proteins. RESULTS: Before the addition of ZD7288, the experimental and control groups showed significant differences in the frequency and amplitude of the spontaneous contraction of isolated ureteral smooth muscle strips. After ZD7288 was added, the frequency and amplitude of the contractions of the ureteral smooth muscle strips were significantly lower in both groups. The differences observed before and after ZD7288 treatment in each group were significant (P < 0.001), and the difference in contraction amplitude observed between the two groups before ZD7288 was also significantly different (P < 0.001). By using WB technology, we showed that the expression of HCN channels was present in normal human ureters, with the expression of HCN4 and HCN1 being the highest; the expression of HCN4 and HCN1 in the control and experimental groups were both statistically significant (P < 0.001). HCN4 and HCN1 were expressed in the mucosal and smooth muscle layers of human control ureters and tuberculous ureters, as revealed by a confocal analysis of double immunostaining for c-kit and HCNs proteins; there were significant differences between the two groups (P < 0.001). CONCLUSION: Four HCN channels are expressed in the ureter, mainly HCN4 and HCN1, suggesting that HCN channels are involved in the peristaltic contraction of ureteral ICCs, which may be an important reason for peristaltic dysfunction in ureteric tuberculosis.

Constitutive Activation of Smoothened in the Renal Collecting Ducts Leads to Renal Hypoplasia, Hydronephrosis, and Hydroureter.

Sonic Hedgehog (Shh) signaling plays a major role in and is essential for regulation, patterning, and proliferation during renal development. Smoothened (Smo) plays a pivot role in transducing the Shh-glioma-associated oncogene Kruppel family member. However, the cellular and molecular mechanism underlying the role of sustained Smo activation in postnatal kidney development is still not clearly understood. Using a conditional knockin mouse model that expresses a constitutively activated form of Smo (SmoM2) upon Homeobox-B7-mediated recombination (Hoxb7-Cre), the effects of Shh signaling were determined in postnatal kidney development. SmoM2;Hoxb7-Cre mutant mice showed growth retardation with a reduction of body weight. Constitutive activation of Smo in the renal collecting ducts caused renal hypoplasia, hydronephrosis, and hydroureter. The parenchymal area and glomerular numbers were reduced, but the glomerular density was increased in SmoM2;Hoxb7-Cre mutant mice. The expression of Patched 1, the receptor of Shh and a downstream target gene of the Shh signaling pathway, was highly restricted and it was upregulated in the inner medullary collecting ducts of the kidney. The proliferative cells in the mesenchyme and collecting ducts were decreased in SmoM2;Hoxb7-Cre mutant mice. This study showed for the first time that sustained Smo inhibits postnatal kidney development by suppressing the proliferation of the mesenchyme and medullary collecting ducts in mice.

Hnf1b and Pax2 cooperate to control different pathways in kidney and ureter morphogenesis.

The transcription factors HNF1B and Pax2, co-expressed in the Wolffian duct and ureteric bud epithelia, play essential roles during the early steps of mouse kidney development. In humans, heterozygous mutations in these genes display a number of common kidney phenotypes, including hypoplasia and multicystic hypoplastic kidneys. Moreover, a high prevalence of mutations either in HNF1B or PAX2 has been observed in children with renal hypodysplasia. To gain a better understanding of Hnf1b and Pax2 interactions in vivo, we generated compound heterozygous mice for Hnf1b and Pax2 null alleles. We show here that compound heterozygous mutants display phenotypes similar to severe congenital anomalies of the kidney and the urinary tract (CAKUT), including strong hypoplasia of the kidneys, caudal ectopic aborted ureter buds, duplex kidneys, megaureters and hydronephrosis. At a molecular level, compound mutants show a delay in nephron segment and medullar interstitial differentiation, increased apoptosis and a transient decrease in Lim1 and Wnt4 expression. We also observe a perturbation of smooth muscle differentiation around the ureter associated with a local down-regulation in transcript levels of Bmp4 and Tbx18, two key regulators involved in ureter smooth muscle formation, thus explaining, at least in part, megaureters. These results together uncover a novel role of Hnf1b as a modifier of the Pax2 haplo-insufficient phenotype and show that these two transcription factors operate in common pathways governing both kidney morphogenesis and ureter differentiation. This mouse model should provide new insights into the pathogenic mechanisms of human CAKUT, the most frequent developmental defect identified in newborns.

IgG4-associated inflammatory pseudotumor of ureter: clinicopathologic and immunohistochemical study of 3 cases.

Inflammatory pseudotumors are lesions characterized by proliferation of fibroblasts/myofibroblasts with variable chronic inflammatory cell infiltration. Recent studies have suggested that inflammatory pseudotumor with abundant IgG4-positive plasma cells may be a unique entity associated with systemic IgG4-related sclerosing disease and should be distinguished from other similar lesions such as inflammatory myofibroblastic tumor and fibrohistiocytic-type inflammatory pseudotumor. Localized inflammatory pseudotumor has been rarely reported in the ureter, and IgG4-associated inflammatory pseudotumor of ureter has not been described. We describe herein 3 cases of ureteral inflammatory pseudotumor of IgG4-associated lymphoplasmacytic type, focusing on density of IgG4-positive plasma cells; infiltration pattern of eosinophils and histiocytes; presence of obliterative phlebitis; and immunohistochemical profiles of smooth muscle actin, anaplastic lymphoma kinase, and CD68. Three patients, 45- and 47-year-old men and 84-year-old woman, all presented with flank pain and ureteral narrowing by a mass effect. Microscopic examination of the resected ureters showed suburothelial masslike lesions with fibroblasts/myofibroblasts without atypia, abundant plasma cells, and scattered eosinophils and histiocytes. The lesion of the 47-year-old man showed obliterative phlebitis in addition to the above findings. The lesion of the 84-year-old woman was accompanied by urothelial carcinoma in situ in the overlying urothelium. Spindle cells were diffusely or focally positive for smooth muscle actin but negative for anaplastic lymphoma kinase in all 3 cases. For each case, respectively, an average of 154, 112, and 50 plasma cells per high-power fields were immunoreactive for IgG4, a diagnostic feature of IgG4 inflammatory pseudotumor. We described 3 cases of IgG4-associated inflammatory pseudotumor of ureter with pathologic and immunohistochemical features that are compatible for lymphoplasmacytic type of inflammatory pseudotumor. Further study is needed to characterize any relationship between this entity and systemic sclerosing disease and/or urothelial carcinogenesis.

Ureteral endometriosis: clinicopathological and immunohistochemical study of 7 cases.

Ureteral endometriosis is a rare yet important entity that can lead to renal failure due to silent obstruction of the ureter. Awareness of clinical and morphologic features can help in early detection and treatment. We analyzed the clinical, pathologic, and immunohistochemical findings of 7 cases of ureteral endometriosis. Mean age of patients was 51 years. All patients presented with hydroureter, accompanied in the most cases by hydronephrosis. Superimposed pyelonephritis was experienced by 2 of 7 patients. Most patients (4 of 7) had previously undergone total abdominal hysterectomy with bilateral salpingo-oophorectomy. In 6 of 7 cases, endometriosis involved the left ureter. The distal one third of the ureter was involved in 6 cases, whereas the middle third was involved in 1 case. In 4 cases, endometriosis was located extrinsic to the ureter, whereas in 3 cases, the ureter showed intrinsic involvement by endometriosis. One case showed simple endometrial hyperplasia. Surgical management included nephrectomy in 2 cases, distal ureterectomy with reimplantation in 3 cases, ureteral stent placement followed by ureteroureterostomy in 1 case, and relief of ureteral obstruction by resection of pelvic endometrioma in 1 case. Immunostains for cytokeratin-7 (CK7) and progesterone receptor (PR) were positive in all of the cases, whereas immunostains for estrogen receptor (ER) were positive in 83% of cases and immunostains for CK20 were negative in all cases. CA125 immunostains were positive in 67% of cases. The stromal cells were positive for CD10, ER, and PR immunostaining. Our findings suggest that the diagnosis of ureteral endometriosis is preceded in most cases by hysterectomy and bilateral salpingo-oophorectomy, possibly because of prior symptoms related to adenomyosis or pelvic endometriosis and that ureteral endometriosis has a strong predilection for involvement of the lower third of the left ureter. Ureteral endometriosis should be included in the differential diagnosis of obstructive ureteral lesions in women, particularly those involving the lower third of the left ureter, even in postmenopausal patients. Immunostains for ER, PR, CK7, CA125, and CD10 can be helpful in challenging cases.

Unusual recurrence in ureters and maxillary sinus of Langerhans cell histiocytosis involving mastoid bone.

We present a case of Langerhans cell histiocytosis (LCH) diagnosed in the mastoid bone. The tumor recurred in the ureter and maxillary sinus mucosa two years later. The diagnosis of LCH was based on morphology and immunohistochemistry. Involvement of the ureter and the maxillary sinus in LCH is extremely rare. To the best of our knowledge, this is the first case of LCH affecting the mastoid bone in a 16-year-old boy and recurring later in the ureter and maxillary sinus mucosa.

Ureteral amyloid deposits of beta 2-microglobulin origin in both kidney recipients of 1 donor.

We report on 2 renal transplant recipients with ureteral amyloid deposits, each of whom received 1 kidney from the same donor. Ureteral stenosis developed in both cases. Immunohistochemistry revealed beta 2-microglobulin derived AB amyloid within the stenotic parts of the ureters, which to our knowledge has not been described previously at that site. Usually AB amyloid is found in patients on long-term hemodialysis. Amyloid transfer by transplantation as a possible cause for ureteral stenosis was excluded because the donor had had normal renal function and autopsy showed no evidence of amyloidosis. It is more likely that the secondary deposit of AB amyloid in the transplanted ureters was facilitated by preexisting ischemic ureteral damage.

Bile acids do not regulate the intestinal mucosal cholesterol synthesis: studies in the chronic bile duct-ureter fistula rat model.

Control male Wistar rats with intact bile circulation, animals with a bile duct-right ureter fistula, and bile duct-right ureter fistula rats fed taurocholic acid (5.5 mg/day) were maintained on a cholesterol-free pellet diet and pulse labeled subcutaneously with radioactive cholesterol. Bile acid feeding did not interfere with the synthesis of cholesterol by the intestinal mucosa or by the whole body in spite of markedly lowering the production of bile acids. Of the total fecal cholesterol mass in bile fistula animals roughly 25% originated from plasma filtration and 75% was ascribed to local mucosal cholesterol synthesis.

Ureteral occlusion decreases phospholipid and cholesterol of renal tubular membranes.

Unilateral ureteral obstruction of 24 h duration in the dog results in a 20% decrease in the amount of total phospholipids present in basolateral membranes of renal tubular cells obtained from the experimental kidney as compared with the amount of phospholipid in basolateral membranes prepared from the contralateral kidney of the same dogs or from the kidneys of normal sham-operated dogs. There was also a decrease in the content of cholesterol and cholesterol esters of the basolateral membranes from the experimental kidney. By contrast, no significant change in lipid content was observed in brush border membranes obtained from the experimental kidney of dogs with unilateral ureteral obstruction. The decrease in phospholipid content of basolateral membranes was accompanied by a 40% fall in the content of phosphatidylcholine and a 12% fall in sphingomyelin. There was a small (12%) but significant increase in the content of phosphatidylethanolamine in basolateral membranes. The mechanisms responsible for the selective decrease in phospholipid content of basolateral membranes remain to be established. It is postulated that changes in solute transport and altered response to hormones observed in the postobstructed kidney of animals with unilateral ureteral obstruction may be explained, at least in part, by changes in the lipid composition of basolateral membranes.

The contents of contractile proteins in the normal and dilated ureter.

Using an SDS-polyacrylamide gel electrophoresis, the contractile protein content of the normal rabbit ureter was compared with that of the dilated ureter. The relative amounts of the actin and myosin were significantly decreased in the dilated ureter.

Sequestration of ureteric segments in dogs.

In 2 separate series of dogs a segment of ureter was isolated from both bladder and kidney and left in situ with an intact blood supply. Tense cysts formed in these sequestered segments regardless of whether the ends were occluded or the segments were split longitudinally and left open. The formation of these cysts can be prevented by the removal of the urothelium. The cyst contents were found consistently to have a sodium concentration below that of the simultaneously obtained serum concentration and urea concentration higher than the simultaneously obtained serum urea. Osmolalities and protein levels within the cysts were virtually identical to the serum levels.

The elastic tissue of the adult dilated ureter.

Adult dilated ureters have been examined in order to calculate the amount of the elastic tissue. From the histological observations and by the chemical analyses performed on the extracted elastin a decrease of the elastic tissue, as compared to the normal adult ureters has been noted. In fact, in the adult normal ureters, the elastin accounts for 9% of the dry matter, while in the abnormal the elastin represents 6.5%.