Erythropoietin promotes functional recovery via anti-apoptotic mechanisms in mouse unilateral ureteral obstruction

The purpose of the work was to investigate mechanisms of erythropoietin-induced protection and accelerated recovery of kidneys and ureters from obstructive injury. Unilateral ureteral obstruction was established for 24, 48, and 72 h in C57BL/6 mice using a non-traumatic micro-clip followed by the microscopic quantification of ureteral peristalsis pre- and post-obstruction. Expression of erythropoietin, erythropoietin receptor, β-common receptor, and downstream apoptosis-related markers was assessed by RT-PCR and immunohistochemistry in ureters and kidneys and compared to the respective organs on the contralateral side within each animal. Expression of genes in kidneys and ureters from mice treated with 20 IU of erythropoietin daily for 72 h prior to obstruction was compared to that of untreated mice following obstruction. Apoptosis in ureteral tissues after 72-h obstruction was assessed via TUNEL assay. Ureteral obstruction increased apoptosis in affected ureters, with peristaltic function halted following all periods of obstruction. Erythropoietin treatment suppressed apoptosis in obstructed tissues and increased the percentage of mice retaining ureteral function immediately following obstruction reversal. Erythropoietin, erythropoietin receptor, Bcl-2, and Bcl-xl mRNA expression were down-regulated, while phospho-Nf-ĸb p65 was up-regulated in ureteral epithelia following obstruction. Erythropoietin treatment induced anti-apoptotic signaling via down-regulated Bax mRNA expression and abrogated phospho-Nf-ĸb p65. Erythropoietin-induced protection of ureteral function and accelerated recovery post-obstruction removal is mediated via anti-apoptotic mechanisms. Ureteral function is disrupted even following obstruction removal, negatively affecting renal function due to delayed recovery. Thus, our results represent a potential target for the development of safe therapeutic agents aimed at improving functional recovery from obstructive injury.

Protein kinase C inhibitor chelerythrine attenuates partial unilateral ureteral obstruction induced kidney injury in neonatal rats

The present study aimed to evaluate the renoprotective effects of chelerythrine (CHE), a protein kinase C inhibitor, on neonatal rats after partial unilateral ureteral obstruction (UUO) surgery. New born Sprague Dawley rats were subjected to partial UUO 48 h after birth and received a daily intraperitoneal injection of 5 mg/kg CHE. At 21-day age, the rats were scarified and the kidneys were collected for analysis. Results showed that CHE treatment significantly increased kidney weight and restored renal function in the obstructed kidney. Histological examination demonstrated that CHE attenuated renal injury by reducing renal parenchymal loss and preventing glomerular and tubular degeneration. In addition, CHE inhibited partial UUO-induced upregulated kidney injury molecule-1 expression and apoptosis and renal fibrosis. Moreover, as a PKC inhibitor, CHE significantly inhibited PKCα and PKCβ membrane translocation. This action may be associated with its effects of anti-apoptosis and anti-fibrosis and contribute to the renoprotection. This short-term study suggests that CHE is beneficial for obstructive nephropathy in neonatal rats and provides foundation for further studies to reveal the long-term effects of CHE on obstructive nephropathy in children and infants.

Expression of apoptosis-related factors in muscles infected with Trichinella spiralis

We found that the expression of mitochondrial apoptosis related genes (Bcl-2 associated protein X, BAX; apoptotic protease activating factor 1, Apaf-1; Caspase 9 and serine/threonine protein kinase, PKB) is elevated in Trichinella spiralis-infected muscles during encapsulation. Micro-dissection of the capsule and subsequent reverse transcription polymerase chain reaction (RT-PCR) confirmed that the expressions of these genes are restricted to the nurse cell. Immunocytochemistry revealed that pro-apoptosis factor (BAX, Apaf-1 and Caspase 9) are predominantly expressed in the basophilic cytoplasm (infected muscle cell origin) and anti-apoptosis factor (PKB) in the eosinophilic cytoplasm (satellite cell origin) of the nurse cell. Electron microscopy revealed that the pre-existing mitochondria in the muscle cells became swollen and disappeared immediately after newborn larva invasion, but new mitochondria of smaller size appeared in the cytoplasm. Nuclear fragmentation and condensation were observed in basophilic cytoplasm which is known to die. Together, the results suggest that the infected muscle cells transform but die through the process of apoptosis which is triggered by factors from the newly formed mitochondria. The anti-apoptosis factor may help the eosinophilic cytoplasm with its survival to ensure nurse cell function.

Release of cytochrome c and activation of caspases related to myocyte apoptosis in obstructed ureters in a rat model of obstructive uropathy

OBJECTIVE

To investigate the roles of cytochrome c and caspases in the pathogenesis of muscular damage in obstructed ureters in a rat model.

MATERIALS AND METHODS

Apoptotic cells were detected using in situ end-labelling of DNA fragments. The expression of cytochrome c, and caspases-3, -8 and -9 was examined in 54 rats, using immunohistochemistry.

RESULTS

The severity of ureteric smooth muscle damage increased during obstruction. Apoptotic myocytes, and the expression of cytochrome c and the three caspases in the smooth muscle layer were apparent 14 days after ligation, reaching a peak at 21 days. The numbers of apoptotic cells in the smooth muscle layer correlated significantly with expression of cytochrome c and the three caspases (r = 0.8673, 0.8701, 0.5723 and 0.7910, respectively; all P < 0.01). The expression of cytochrome c in the smooth muscle layer correlated significantly with the expression of the three caspases (r = 0.8234, 0.7558 and 0.7825, respectively; all P < 0.001). The expression of caspase-3 and -8, and -3 and -9 also correlated significantly (r = 0.6721 and 0.8501, respectively; both P < 0.002).

CONCLUSIONS

Cytochrome c and caspases are involved in ureteric myocyte apoptosis; the release of cytochrome c might be important in ureteric damage during obstructive uropathy.

Pelviureteral junction obstruction: correlation of renal cell apoptosis and differential renal function

PURPOSE

We evaluated the relationship between renal biopsy changes and preoperative and postoperative renal scans in 29 male and 14 female infants with prenatal severe hydronephrosis and unilateral ureteropelvic junction obstruction. We also verified on immunohistochemical studies glomerular changes, degeneration of the epithelium of the proximal tubules, interstitial fibrosis and inflammation and apoptotic nuclei.

MATERIALS AND METHODS

In the children, all with prenatal diagnosis of hydronephrosis, ureteropelvic junction obstruction was diagnosed with 99mtechnetium mercaptoacetyltriglycine renal scan performed in all patients at ages 4 to 6 weeks to establish baseline differential renal function. All patients underwent renal biopsies at the time of pyeloplasty. The biopsy samples were examined with histological and immunohistochemical methods for antigens associated with apoptosis, such as clusterin, CD95, TDAG51 and bcl-2. Renograms were performed 3 months after surgical repair.

RESULTS

The male-to-female ratio was 2.1:1. There was no difference between males and females in regard to baseline differential renal function of the affected kidney. All biopsy samples confirmed degeneration of the epithelium of the proximal tubules, interstitial focal fibrosis was found in 4 samples, mild chronic inflammation with lymphoid aggregates in 4 and focal Bowman's space dilatation in 1. No specimen demonstrated apoptotic nuclei as confirmed by immunohistochemical study which showed the presence of bcl-2 and absence of CD95, TDAG51 and clusterin, probably because there was no dysplasia in the samples examined.

CONCLUSIONS

These results indicate absence of apoptosis in the kidney with preoperative uptake less than 40% and minimal histological changes.

Urinary outflow obstruction increases apoptosis and deregulates Bcl-2 and Bax expression in the fetal ovine bladder

During organogenesis, net growth of tissues is determined by a balance between proliferation, hypertrophy, and apoptotic death. Human fetal bladder outflow obstruction is a major cause of end-stage renal failure in children and is associated with complex pathology in the kidney and lower urinary tract. Experimental manipulation of the fetal sheep urinary tract has proved informative in understanding the pathobiology of congenital obstructive uropathy. In this study we used an ovine model of fetal bladder outflow obstruction to examine effects on apoptotic cell death in the developing urinary bladder. While 30 days of obstruction in utero between 75 and 105 days gestation resulted in overall growth of the fetal bladder as assessed by weight, protein, and DNA measurements, we found that apoptosis, as assessed by in situ end-labeling, was up-regulated in fetal bladder detrusor muscle and lamina propria cells and that this was accompanied by a down-regulation of the anti-death protein Bcl-2 and an up-regulation of the pro-death protein Bax. Moreover, activated caspase-3, an effector of apoptotic death, was increased in obstructed bladders. This is the first study to define altered death in an experimental fetal model of bladder dysmorphogenesis. We speculate that enhanced apoptosis in detrusor smooth muscle cells is part of a remodeling response during compensatory hyperplasia and hypertrophy. Conversely, in the lamina propria, an imbalance between death and proliferation leads to a relative depletion of cells.