Poly(ADP-ribose) polymerase is involved in the development of diabetic cystopathy via regulation of nuclear factor kappa B

OBJECTIVES

To investigate whether overactivated Poly (ADP-ribose) polymerase (PARP) and subsequent activation of nuclear factor kappa B (NF-κB) correlate with the development of diabetic cystopathy via induction of bladder apoptosis. Diabetic cystopathy as a common complication of diabetes is frequently associated with increased oxidative stress and apoptosis of the bladder. PARP is activated by hyperglycemia-induced oxidative stress and plays a critical role in cell apoptosis and the development of diabetic complications, such as retinopathy and nephropathy.

METHODS

Sprague-Dawley rats were divided into 3 groups: control, diabetic, and diabetic treated with PARP inhibitor (DM+Vit-B3). Four weeks after induction of diabetes, the DM+Vit-B3 group was treated with PARP inhibitor (nicotinamide, 400 mg/kg/d) for 3 weeks. Bladder function was then assessed by conscious cystometry. The extent of oxidative stress and apoptosis, expression of poly(ADP-ribose) (PAR), NF-κB, phosphorylated inhibitor of NF-κB (IκB)-α, Bcl-2, and Bax in the bladder were also investigated.

RESULTS

Bladder dysfunction was strongly associated with increased oxidative stress and bladder apoptosis. In addition, the amount of PAR, phosphorylated IκB-α, expression of NF-κB, and Bax were significantly increased in diabetic rat bladder. Inhibition of PARP significantly reduced PARP activation and expression of NF-κB and Bax. As a result, bladder apoptosis was attenuated and bladder function was improved.

CONCLUSIONS

These results indicate that overactivated PARP and subsequent activation of NF-κB play important roles in the development of diabetic cystopathy via induction of bladder apoptosis. These findings may be applied in the development of novel therapies for patients with diabetic cystopathy.

Effects of poly(ADP-ribose) polymerase inhibition in bladder damage caused by cyclophosphamide in rats

It was previously shown that nitric oxide produced by inducible nitric oxide synthase (iNOS) and peroxynitrite are responsible for cyclophosphamide (CP)-induced cystitis. Since endogenous production of peroxynitrite is known to lead to poly(ADP-ribose) polymerase (PARP) activation, in this study, the aim was to evaluate whether the PARP activation pathway is also included in the pathogenesis of CP-induced bladder ulceration in rats. A total of 48 male albino Wistar rats were divided into 5 groups. Group 1 served as control and was given 2 ml saline; four groups received a single dose of CP (200 mg/kg) with the same time intervals. Group 2 received CP only; Group 3, selective iNOS inhibitor 1400W (20 mg/kg); Group 4, peroxynitrite scavenger ebselen (30 mg/kg); and Group 5, PARP inhibitor 3-aminobenzamide (20 mg/kg). CP injection resulted in severe cystitis with continuous macroscopic hemorrhage, strong edema, inflammation, and ulceration. Moreover, bladder iNOS activation and urine nitrite-nitrate levels were dramatically increased. Histologically, 1400W protected bladder against CP damage and decreased urine nitrite-nitrate levels and bladder iNOS induction. Ebselen has shown similar histologic results with 1400W without changing urinary nitrite-nitrate level and iNOS activity. Furthermore in the 3-aminobenzamide group, beneficial effects had also occurred including decreased ulceration. These results suggest that PARP activation involves pathogenesis of CP-induced bladder ulceration. Furthermore, PARP is not only important for ulceration but also for bladder edema, hemorrhage, and inflammation because of broken uroepithelial cellular integrity.

Tumor necrosis factor alpha- and inducible nitric oxide synthase-producing dendritic cells are rapidly recruited to the bladder in urinary tract infection but are dispensable for bacterial clearance

The role of dendritic cells (DC) in urinary tract infections (UTI) is unknown. These cells contribute directly to the innate defense against various viral and bacterial infections. Here, we studied their role in UTI using an experimental model induced by transurethral instillation of the uropathogenic Escherichia coli (UPEC) strain 536 into C57BL/6 mice. While few DC were found in the uninfected bladder, many had been recruited after 24 h, mostly to the submucosa and uroepithelium. They expressed markers of activation and maturation and exhibited the CD11b+ F4/80+ CD8- Gr-1- myeloid subtype. Also, tumor necrosis factor alpha (TNF-alpha)- and inducible nitric oxide synthase (iNOS)-producing CD11bINT DC (Tip-DC) were detected, which recently were proposed to be critical in the defense against bacterial infections. However, Tip-DC-deficient CCR2-/- mice did not show reduced clearance of UPEC from the infected bladder. Moreover, clearance was also unimpaired in CD11c-DTR mice depleted of all DC by injection of diphtheria toxin. This may be explained by the abundance of granulocytes and of iNOS- and TNF-alpha-producing non-DC that were able to replace Tip-DC functionality. These findings demonstrate that some of the abundant DC recruited in UTI contributed innate immune effector functions, which were, however, dispensable in the microenvironment of the bladder.

Aqueous extract of Trigonella foenum-graecum L. ameliorates additive urotoxicity of buthionine sulfoximine and cyclophosphamide in mice

Cyclophosphamide (CP) is a commonly used anti-cancer drug which causes toxicity by its reactive metabolites such as acrolein and phosphoramide mustard. In the present study modulation of toxicity caused by concomitant exposure to CP and l-buthionine-SR-sulfoximine (BSO) by fenugreek (Trigonella foenum-graecum L.) extract was evaluated by measuring lipid peroxidation (LPO) and anti-oxidants in urinary bladder in mice. Fenugreek, a common dietary and medicinal herb, showed protective effect not only on LPO but also on the enzymatic anti-oxidants. CP-treated animals exhibited a significant decrease in the activities of glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GP) and catalase (CAT) when compared to the controls. Level of reduced glutathione (GSH) was also reduced with an increase in LPO in CP-treated animals. BSO treatment depicted an additive toxic effect in CP-treated animals. Pre-treatment of herbal extract restored activities of all the enzymes and thus showed an overall protective effect on additive effect of CP and BSO. Restoration of GSH by extract treatment may play an important role in reversing CP-induced apoptosis and free radical-mediated LPO in urinary bladder. Fenugreek, known for its hypoglycemic, anti-inflammatory and immunomodulatory activity, may be a promising protective medicinal herb for consideration in complementary therapy in cancer patients under chemotherapeutic interventions.

Spinal ERK activation contributes to the regulation of bladder function in spinal cord injured rats

The extracellular signal-regulated kinase 1 and 2 (ERK) pathway, regulated by phosphorylation on specific amino acids, is emerging as an important signaling cascade in neurones, transducing sensory input into cellular responses. In the mammalian nervous system, the ERK pathway has been found to mediate plasticity events. Particularly, in the spinal cord, ERK play an important role in allodynia and hyperalgesia. Recently, it was demonstrated that ERK activation is upregulated in the spinal cord of rats with chronic bladder inflammation and contributes to bladder overactivity. Thus, in this study we sought to assess the involvement of ERK in micturition reflexes associated to spinal cord injury (SCI) in the rat. Bladder function in chronic SCI rats was altered compared to spinal intact rats. PhosphoERK levels were upregulated in the L6 spinal cord segment, particularly after saline infusion for 2 h. The increase in spinal ERK phosphorylation was specifically restricted to L6 spinal segment. No variation in the levels of total ERK protein was observed. Intrathecal administration of PD98059, a specific inhibitor of ERK phosphorylation, reduced the frequency and amplitude of bladder contractions in SCI animals but not in spinal intact ones. Overall, our results demonstrate increased activation of the ERK pathway in the spinal cord from SCI rats, restricted to spinal segments that receive sensory input arising from the bladder. Since the use of PD98059 reduced the frequency and amplitude of bladder contractions, ERK inhibitors may provide a new therapeutic approach to the treatment of bladder overactivity after spinal injuries.

Oxidative stress plays a role in diabetes-induced bladder dysfunction in a rat model

OBJECTIVES

To evaluate the oxidative status of the bladder 8 weeks after diabetes induction. Oxidative stress has recently been implicated in the pathogenesis of diabetes complications, but its role in diabetic cystopathy has not been studied.

METHODS

Sprague-Dawley rats were divided into three groups: control (n = 11), diuretic control (5% sucrose drink; n = 6), and streptozotocin-induced diabetic group (n = 14). Eight weeks later, the bladders were dissected. We measured the antioxidant scavenging enzymes (catalase and superoxide dismutase)-like activity and the levels of the thiobarbituric acid reactive substances, as a marker of lipid peroxidation. We also examined the levels of inducible nitric oxide synthase and apoptosis in the bladders.

RESULTS

We found a statistically significant reduction in the catalase-like activity in the bladders from the diabetic group compared with the other groups (P = 0.017, diabetic versus control); the difference in the superoxide dismutase-like activity was not statistically significant among the groups. The thiobarbituric acid reactive substances levels were significantly greater in the diabetic compared with other groups (131.9 +/- 47.5, 46.7 +/- 17.9, and 60.9 +/- 25.4 nmol/mg protein in the diabetic, control, and diuretic group, respectively, P = 0.006, diabetic versus control). Immunohistochemical and apoptosis studies showed a statistically significant increased number of inducible nitric oxide synthase-positive cells and apoptotic cells in the diabetic bladder smooth muscle cells (P <0.001).

CONCLUSIONS

Our findings showed that oxidative stress occurred in the bladders of the STZ-diabetic rats and was not mediated by diuresis. The oxidative damage of the smooth muscle cells may be a contributory factor in diabetic cystopathy.

Anaplastic lymphoma kinase (ALK 1) staining and molecular analysis in inflammatory myofibroblastic tumours of the bladder: a preliminary clinicopathological study of nine cases and review of the literature

Inflammatory myofibroblastic tumours (IMFT) may arise at any anatomical site, including lung, soft tissues, retroperitoneum and bladder. Although morphologically similar, these lesions encompass a spectrum of entities with differing aetiology, ranging from reactive/regenerative proliferations to low-grade neoplasms with a risk of local recurrence, but no significant metastatic potential. Vesical IMFT usually presents as a polypoid mass with a pale firm cut surface and can be of considerable size, mimicking a malignant tumour clinically and radiologically. Its good outcome, however, warrants conservative surgical excision, emphasising the importance of identification and distinction from malignant tumours of the bladder that may require more radical surgery and/or adjuvant therapy. We conducted a preliminary retrospective, comparative immunocytochemical study of 20 bladder tumours, including nine IMFTs, five spindle cell (sarcomatoid) carcinomas, two rhabdomyosarcomas, two leiomyosarcomas and two neurofibromas. The results confirmed IMFT positivity for smooth muscle actin, desmin and cytokeratin in 78-89% cases, resulting in potential confusion with sarcomatoid carcinoma or leiomyosarcoma. In contrast, cytoplasmic anaplastic lymphoma kinase (ALK 1) staining was present in eight IMFT (89%), but was not seen in any other lesion examined. The ALK 1 staining was confirmed by fluorescence in situ hybridisation, with translocation of the ALK gene present in 15-60% tumour cells in four of six IMFT examined, but not in four cases of sarcomatoid carcinoma or three of leiomyosarcoma. In conclusion, ALK 1 staining may be of value in the distinction of vesical IMFT from morphologically similar entities, and often reflects ALK gene translocations in these lesions.

Nitric oxide synthase immunoreactivity in human bladder carcinoma

AIMS

To study the expression of the endothelial and inducible isoforms of nitric oxide synthase (eNOS and iNOS, respectively) in human bladder carcinoma and schistosomal bladder disease, and to compare it with normal adult and fetal urothelium. Nitric oxide is thought to play a complex role in human carcinogenesis, but has only recently been investigated in bladder cancer.

METHODS

Immunohistochemistry was performed on paraffin wax embedded sections of 33 human bladder carcinomas and five bladder carcinoma cell lines; in addition, seven schistosomal bladder cases and normal and fetal urothelium were investigated. In the cell lines enzymatic activity was examined by the NADPH diaphorase reaction.

RESULTS

Immunoreactivity for eNOS was present in most cells of all 31 cases examined. Immunoreactivity for iNOS was less abundant and was seen in 23 of 25 cases. Similar findings were noted in schistosomal bladder cancer. In the normal bladder mucosa, eNOS immunoreactivity was found only in the superficial cell layer and iNOS was not expressed, whereas in the fetal urothelium immunoreactivity for both isoforms was seen in all cell layers. Enzymatic activity and immunoreactivity for eNOS and iNOS were evident in the five bladder carcinoma cell lines.

CONCLUSIONS

It is possible that NOS plays a role in the differentiation of the transitional epithelium in fetal life, has a biological function in the adult bladder mucosa, and is involved in bladder carcinogenesis. eNOS and iNOS immunoreactivity do not differ in schistosomal and non-schistosomal bladder carcinoma, but resemble the pattern of expression typical of fetal urothelium.

Alterations in the nitric oxide synthase binding sites and non-adrenergic, non-cholinergic mediated smooth muscle relaxation in the diabetic rabbit bladder outlet: possible relevance to the pathogenesis of diabetic cystopathy

PURPOSE

To investigate the effect of diabetes mellitus (DM) on the density and distribution of nitric oxide synthase (NOS) and the smooth muscle responses to non-adrenergic, non-cholinergic (NANC) nerve stimulation and exogenous nitric oxide (NO) in the rabbit lower urinary tract.

MATERIALS AND METHODS

Transverse sections of detrusor, bladder neck and urethra, from control and six months alloxan-induced DM New Zealand White rabbits were incubated with a radioligand for NOS ([3H]-L-N(G)-nitroarginine). Densitometric analysis was performed on the autoradiographs. NADPH diaphorase histochemistry was also used as a marker for NOS activity. Responses to NANC nerve stimulation (5 to 20 Hz) and to NO (10(-6) to 3x10(-4) M.) on smooth muscle strips from detrusor, bladder neck and urethra were measured in organ baths.

RESULTS

NOS binding sites were significantly (p<0.03) more dense in the bladder neck than in the detrusor in both DM and control groups. In DM bladder neck, NOS binding sites were significantly (p<0.04) increased compared with the controls. NADPH diaphorase activity appeared markedly increased in the detrusor, bladder neck and urethra of DM animals compared with controls. The mean IC50 for exogenous NO in control versus DM were not statistically different in the bladder neck (1.03x10(-4) M versus 9.8x10(-5) M) and urethra (8.1x10(-5) M versus 8.8x10(-5) M), but the relaxations to 5x10(-6) M of NO were significantly impaired (p<0.04) in the DM urethral smooth muscle. NANC nerve-mediated relaxations were significantly impaired (p<0.001) in the DM urethral smooth muscle.

CONCLUSIONS

Alterations of both the NOS binding sites and functional responses to NANC nerve stimulation suggest that NO may have a pathophysiological role in the urinary bladder dysfunction associated with DM.

Telomerase activity in malignant and benign bladder conditions

This study investigated whether the enzyme telomerase is active in bladder tumours, whether there is any correlation between activity and grade, and whether the enzyme is expressed in non-malignant conditions. Fifty-two patients undergoing cystoscopy or TURBT at a district general hospital were included, 25 with current bladder tumours, 13 with previous but no current tumours, and 14 with non-malignant pathology. Specimens were analysed by the telomerase repeat amplification protocol (TRAP assay), a highly-sensitive polymerase chain reaction (PCR)-based assay, and a commercially-available ELISA kit. Telomerase activity was detected in 80% of bladder tumours, more frequently in moderate- or poorly-differentiated (93%) than well-differentiated (56%) tumours. Activity was not uniform across individual tumours. Telomerase was also frequently (61%) detected in inflammatory lesions found in patients being followed up for previous bladder tumours, and in two (14%) patients with benign pathologies. In conclusion, telomerase was frequently but not uniformly detected in bladder tumours; its presence was not specific to malignancy. There is a possible correlation between tumour grade and telomerase activity.

The 28K protein in urinary bladder, squamous metaplasia and urine is triosephosphate isomerase

OBJECTIVES

The objective of this study was to establish the identity of a protein found in high concentrations in squamous metaplasia of the bladder.

DESIGN AND METHODS

The protein was isolated and subjected to a series of physical, chemical, and catalytic studies.

RESULTS

In the normal urothelium the protein was confined to a juxtanuclear pattern on the luminal side of the umbrella cells; in squamous metaplasia and squamous cell carcinoma the protein was increased and exhibited a more diffuse intracellular distribution. The protein was found to be identical to triosephosphate isomerase (EC 5.3.1.1; TPI) with respect to its immunological properties, native and subunit molecular weights, electrophoretic mobility, catalytic activity, and amino acid sequence.

CONCLUSIONS

While the basis for the altered distribution of TPI remains to be established, the increased amounts of the protein in urine or bladder tissue may be indicative of squamous metaplasia, squamous cell carcinoma, or other bladder injuries.

Antioxidant deficiency following clam enterocystoplasty

OBJECTIVE

To assess whether there is a reduction in serum antioxidant activity in patients who have undergone a clam enterocystoplasty procedure.

PATIENTS AND METHODS

Serum glutathione peroxidase (GPase) activity was measured in 20 patients who had undergone clam enterocystoplasty. Serum selenium concentration was also measured in 62 similar patients and compared with 56 healthy controls and 44 patients with a neuropathic bladder, mainly patients with spinal cord injuries who had not undergone surgery.

RESULTS

GPase activity correlated well with serum selenium measurement. There was a significant reduction (P < 0.001) in serum selenium level in young (< 50 years old) non-neuropathic bladder patients following clam enterocystoplasty. This reduction in serum selenium was similar to that found in both unoperated patients with a neuropathic bladder (who are known to have an increased risk of developing bladder cancer) and those patients with a neuropathic bladder who had undergone augmentation. This reduction was not related to urinary tract infection nor the time since surgery.

CONCLUSION

A reduction in serum selenium has been shown to increase susceptibility to bladder cancer following carcinogenic exposure to compounds such as nitrosamines. This study suggests that patients with idiopathic and congenital instability may be at an equally high risk as a result of undergoing this procedure.

Urinary lactic acid dehydrogenase activity and the site of urinary tract infections

A report that elevated urinary lactic acid dehydrogenase (LDH) isoenzyme 5 activity is a reliable tool for separating patients with upper from those with lower urinary tract infections (UTIs) led us to study urinary LDH enzyme activity in girls having bladder washout studies to localize the site of infection. Urinary LDH isoenzyme 5 activity in 64 instances of lower UTI was 16.1 +/- 3.3%, a value not significantly different than that of 18.2 +/- 12.6% found in 26 instances of upper tract infection (t = 0.8726, P = 0.1928). The data show that LDH isoenzyme 5 activity is of no value for localization of the site of a UTI. The data of these studies also showed that urinary LDH enzyme activity clearly separates girls with UTIs from those without infections, but it is unlikely that this finding will be of value in diagnosis or management.

Failure of urinary beta-glucuronidase activity to localize the site of urinary tract infection

The differentiation of renal from bladder bacteriuria is difficult on clinical grounds alone. To evaluate the correlation between site of infection and urinary beta-glucuronidase activity, 46 patients with well documented recurrent bacteriuria were studied by bilateral ureteral catheterization. Urinary beta-glucuronidase activity was also determined in 46 control subjects. In general, asymptomatic patients with renal bacteriuria, either unilateral or bilateral, had levels of enzyme activity in their urine comparable to patients with infection confined to the bladder and to normals. Only 4 of 25 patients with renal bacteriuria had significant elevations of urinary beta-glucuronidase. After localization of infection, 9 of 10 patients treated with kanamycin, a potentially nephrotoxic drug, developed significant elevations of urinary beta-glucuronidase. The results of these studies indicate that determination of beta-glucuronidase activity in urine is not useful in predicting the site of infection in patients with bacteriuria but may find a role in screening for early nephrotoxicity.