Substance P induces localization of MIF/alpha1-inhibitor-3 complexes to umbrella cells via paracellular transit through the urothelium in the rat bladder

BACKGROUND

Macrophage migration inhibitory factor (MIF) is released into the intraluminal fluid during bladder inflammation in the rat complexed to alpha1-inhibitor-3 (A1-I3; a rodent proteinase inhibitor in the alpha-macroglobulin family). The location of A1-I3 in the bladder had not been investigated. Therefore, we examined the location of A1-I3 and MIF/A1-I3 complexes in the bladder and changes due to experimental inflammation.

METHODS

Anesthetized male rats had bladders removed with no treatment (intact) or were injected with Substance P (SP; s.c.; saline vehicle). After one hour intraluminal fluid was removed, bladder was excised and MIF and A1-I3 levels were determined using ELISA and/or western-blotting. MIF co-immunoprecipitation determined MIF/A1-I3 complexes in the bladder. Bladder sections were immunostained for A1-I3 and MIF/A1-I3.

RESULTS

A1-I3 immunostaining was observed in interstitial spaces throughout the bladder (including submucosa) but not urothelium in intact and saline-treated rats. RT-PCR showed that the bladder does not synthesize A1-I3, therefore, A1-I3 in the interstitial space of the bladder must be plasma derived. In SP-treated rats, A1-I3 in the bladder increased and A1-I3 was observed traversing through the urothelium. Umbrella cells that do not show MIF and/or A1-I3 immunostaining in intact or saline-treated rats, showed co-localization of MIF and A1-I3 after SP-treatment. Western blotting demonstrated that in the bladder MIF formed non-covalent interactions and also binds covalently to A1-I3 to form high molecular weight MIF/A1-I3 complexes (170, 130 and 75-kDa, respectively, verified by co-immunoprecipitation). SP-induced inflammation selectively reduced 170-kDa MIF/A1-I3 in the bladder while increasing 170 and 130-kDa MIF/A1-I3 in the intraluminal fluid.

CONCLUSION

A1-I3 and MIF/A1-I3 complexes are resident in bladder interstitium. During SP-induced inflammation, MIF/A1-I3 complexes are released from the bladder into the lumen. Binding of MIF/A1-I3 complexes to urothelial cells during inflammation suggests these complexes participate in the inflammatory reaction through activation of receptors for MIF and/or for A1-I3.

Opposing viscerovisceral effects of surgically induced endometriosis and a control abdominal surgery on the rat bladder

OBJECTIVE

To determine, in rats, how surgically induced endometriosis and a control surgery (partial hysterectomy; sutures in abdomen) affects micturition thresholds and bladder vascular permeability.

DESIGN

Two animal studies, each performed in three groups of urethane-anesthetized rats in proestrus.

SETTING

Academic facility.

ANIMAL(S)

Seventy-three female, regularly cycling Sprague-Dawley rats studied in proestrus.

INTERVENTION(S)

Surgical induction of endometriosis (ENDO), surgical control (shamENDO), intact control (NoSURG), and bladder inflammation via intravesicular turpentine in all three groups.

MAIN OUTCOME MEASURE(S)

[1] Micturition thresholds (MTs; volume voiding thresholds), as measured by repetitive transurethral cystometry before and after bladder inflammation and [2] bladder inflammation, as assessed by extravasation of Evans Blue dye.

RESULT(S)

In the uninflamed bladder, MTs were significantly lower and dye extravasation significantly higher in ENDO rats than in shamENDO and NoSURG rats. Bladder inflammation increased dye extravasation in all groups and reduced MTs in the NoSURG and ENDO rats, but not in the shamENDO rats.

CONCLUSION(S)

Endometriosis reduces MTs and produces signs of inflammation in the healthy bladder. Surprisingly, the control surgical procedure (partial hysterectomy; sutures on mesenteric blood vessels) protects bladder reflexes from the influence of bladder inflammation, a condition that is named silent bladder inflammation. Such cross-system inducing and masking effects have important clinical relevance.

TRPV1 (vanilloid receptor) in the urinary tract: expression, function and clinical applications

The transient receptor potential vanilloid subfamily 1 (TRPV1) is an ion channel activated by capsaicin, heat, protons and endogenous ligands such as anandamide. It is largely expressed in the urinary tract of mammals. Structures in which the receptor expression is firmly established include sensory fibers and urothelial cells, although the presence of TRPV1 in other cell types has been reported. As in other systems, pain perception was the first role attributed to TRPV1 in the urinary tract. However, it is now increasingly clear that TRPV1 also regulates the frequency of bladder reflex contractions, either through direct excitation of sensory fibers or through urothelial-sensory fiber cross talk involving the release of neuromediators from the epithelial cells. In addition, the recent identification of the receptor in urothelial and prostatic cancer cells raise the exciting hypothesis that TRPV1 is involved in cell differentiation. Desensitization of the receptor by capsaicin and resiniferatoxin has been investigated for therapeutic purposes. For the moment, lower urinary tract dysfunctions in which some benefit was obtained include painful bladder syndrome and overactive bladder of neurogenic and non-neurogenic origin. However, desensitization may become obsolete when non-toxic, potent TRPV1 antagonists become available.

Expression of fractalkine and fractalkine receptor in urinary bladder after cyclophosphamide (CYP)-induced cystitis

Alterations in the expression of the chemokine, fractalkine (CX3CL1), were examined in the urinary bladder after cyclophosphamide (CYP)-induced cystitis of varying duration: acute (4 h or 48 h), or chronic (10 day). CYP-induced cystitis significantly (p<or=0.01) increased fractalkine protein expression in the urinary bladder with acute (48 h) and chronic CYP treatment. Western blot analysis also demonstrated significantly (p<or=0.01) increased fractalkine expression in the whole urinary bladder with acute (1.5-2.2-fold) and chronic (3-fold) CYP-induced cystitis. Immunohistochemistry for fractalkine-immunoreactivity revealed little fractalkine-IR in control or acute (4 h) CYP-treated rat urinary bladders except in a vascular bed but showed no colocalization with nerve fibers in the suburothelial plexus in any experimental group. However, expression was significantly (p<or=0.001) upregulated in the urothelium with 48 h or chronic CYP treatment. Similarly, fractalkine receptor (CX3CR1)-IR was significantly (p<or=0.001) upregulated in the urothelium with 48 h or chronic CYP treatment. These studies demonstrated upregulation of the chemokine, fractalkine, in the urinary bladder and specifically in the urothelium with CYP-induced cystitis. Chemokines, and specifically, fractalkine, may be another class of neuromodulatory agents upregulated in the urinary bladder that can affect micturition function and sensory processing with cystitis and may represent novel, drug targets for cystitis.

Involvement of ubiquitination and sumoylation in bladder lesions induced by persistent long-term low dose ionizing radiation in humans

PURPOSE

We determined whether ubiquitination and sumoylation processes are up-regulated in bladder urothelium by chronic, long-term, persistent low doses of ionizing radiation in male patients with benign prostate hyperplasia and females with chronic cystitis living more than 19 years in 137Cs contaminated areas after the Chernobyl accident in Ukraine.

MATERIALS AND METHODS

Bladder urothelial biopsies from 45 patients were subjected to histopathological and immunohistochemical study of Ub, SUMO1, SUMO E2 conjugating enzyme Ubc9, and the cell cycle inhibitors p53 and p27(Kip1).

RESULTS

Of 25 group 1 patients from radio contaminated areas chronic proliferative atypical cystitis (Chernobyl cystitis), featuring multiple foci of dysplasia, and carcinoma in situ were observed in 23 (92%) and 19 (76%), respectively, in addition to 1 small pTa grade 1 urothelial carcinoma. Chronic cystitis with areas of dysplasia and urothelial hyperplasia were detected in 2 (10%) and 3 (15%), respectively of the 20 patients in control group 2 from clean (without radio contamination) areas of Ukraine. Greatly increased levels of Ub, SUMO1, Ubc9 and p53 as well as decreased levels of p27(Kip1) were evident in patients in group 1 compared to those in group 2 (all p <0.001).

CONCLUSIONS

These findings support the hypothesis that up-regulated ubiquitination and sumoylation processes might be an adaptive response to unscheduled proteolysis of aberrant p53 and p27(Kip1) cell cycle regulators occurring with long-term low dose rate ionizing radiation exposure with a possible contribution to urothelial carcinogenesis.

Changes in galanin immunoreactivity in rat micturition reflex pathways after cyclophosphamide-induced cystitis

Alterations in the expression of the neuropeptide, galanin, were examined in micturition reflex pathways of rat after cyclophosphamide (CYP)-induced cystitis of variable duration: acute (4 h), intermediate (48 h), or chronic (10 days). In control animals, galanin expression was present in specific regions of the gray matter in the rostral lumbar and caudal lumbosacral spinal cord, including: (1) the dorsal commissure (DCM); (2) superficial dorsal horn; (3) the regions of the intermediolateral cell column (L1-L2) and the sacral parasympathetic nucleus (SPN, L6-S1); and (4) the lateral collateral pathway (LCP) in lumbosacral spinal segments. Densitometry analysis demonstrated significant decreases (P< or =0.01) in galanin immunoreactivity (IR) in these regions of the L1-S1 spinal cord after acute or intermediate CYP-induced cystitis. In contrast, increases (P< or =0.01) in galanin-IR were observed in the DCM, SPN, or LCP regions in the L6-S1 spinal segments in rats with chronic cystitis. No changes in the number of galanin-immunoreactive cells were observed in the L1-S1 dorsal root ganglia (DRG) after CYP-induced cystitis of any duration. A small percentage of bladder afferent cells (Fast-blue-labeled) in the DRG expressed galanin-IR in control rats; this was not altered with cystitis. Galanin-IR was observed encircling DRG cells after chronic cystitis. These changes may contribute to urinary bladder dysfunction, altered sensation, and referred somatic hyperalgesia after cystitis.

15-Deoxy-Δ12,14-prostaglandin J2 attenuates development of cyclophosphamide-induced cystitis in rats

OBJECTIVES

To investigate whether an endogenous prostaglandin (PG) D2 metabolite, 15-deoxy-Delta12,14-PGJ2 (15d-PGJ2), can attenuate cyclophosphamide (CYP)-induced cystitis in the rat.

METHODS

Male Sprague-Dawley rats received a single intraperitoneal injection of CYP (200 mg/kg). In a separate group of animals, 15d-PGJ2 (10 and 100 microg/kg intraperitoneal bolus 10 minutes before and 24 hours after CYP injection) or a selective inducible nitric oxide synthase (iNOS) inhibitor, N-(3-(aminomethyl)benzyl)acetamidine ([1400W] 10 mg/kg intraperitoneal bolus 10 minutes before and 12 and 24 hours after CYP injection), was administered. At 48 hours after CYP injection, the rats were killed, and tissues were removed for evaluation of cystitis.

RESULTS

CYP injection resulted in severe cystitis. 15d-PGJ2, as well as 1400W, significantly reduced the increase in plasma protein extravasation (Evans blue dye method), iNOS enzymatic activity, urinary excretion of nitric oxide metabolites, and myeloperoxidase activity in the bladder caused by CYP. Moreover, 15d-PGJ2 significantly decreased the cytokine interleukin-1beta in the bladder. In addition, 15d-PGJ2 significantly reduced the degree of CYP-induced bladder tissue damage and increase in immunohistochemical staining for iNOS in the bladder.

CONCLUSIONS

These results indicate that 15d-PGJ2 can attenuate the development of CYP-induced cystitis by suppression of cytokine production and iNOS induction. Thus, treatment with cyclopentenone prostaglandins such as 15d-PGJ2 may be effective against CYP-induced cystitis.

Peptidergic sensory and parasympathetic fiber sprouting in the mucosa of the rat urinary bladder in a chronic model of cyclophosphamide-induced cystitis

In this study, we used a well-established animal model to investigate changes in the peptidergic and parasympathetic innervation of the bladder following chronic bladder inflammation. Adult female Sprague-Dawley rats were injected with either 70 mg/kg cyclophosphamide diluted in saline, i.p., once every 3 days or saline. After 10 days, all animals were tested for urinary frequency and number of low volume voids, as well as symptoms of spontaneous pain. At the end of 12 days, all animals were perfused with histological fixatives and the urinary bladders processed for immunofluorescence using antibodies against calcitonin gene-related peptide and the vesicular acetylcholine transporter as markers, respectively, of peptidergic primary afferent fibers and parasympathetic efferent fibers. We show that animals treated with cyclophosphamide had inflamed bladders and displayed high urinary frequency as well as some indicators of spontaneous pain, such as piloerection and a rounded-back posture. Furthermore, they had a significant increase in the density of both parasympathetic and peptidergic sensory fibers in the bladder mucosa and an increase in peptidergic sensory fibers in the detrusor muscle. Based on these results, we suggest that peripheral sprouting of parasympathetic and peptidergic fibers could be a mechanism responsible for sensitization of the bladder, leading to urinary symptoms. Since we observed that the parasympathetic and peptidergic fibers often wrapped around one another and that their varicosities were very close, these two fiber populations may be interacting with each other to lead to and maintain sensitization. Future studies are required to establish the role of this fiber sprouting in bladder symptoms.

What is the risk of pyelonephritis due to desmopressin in rats with cystitis?

The risk of pyelonephritis in children with asymptomatic cystitis or bacteriuria, using desmopressin for primary nonpoliuric nocturnal enuresis, is not known. The aim of this study was to study whether there is a risk of pyelonephritis in rats with cystitis using desmopressin. Wistar rats (n = 28) were divided into four groups of cystitis (groups I-IV). DDAVP (2 microg daily) and saline (0.5 ml daily) were injected intramuscularly for 7 days in groups II and IV and groups I and III, respectively. The urinalysis, urine culture, and 24-h urinary volume (UV(24)) were assessed for all rats on days 1, 3, 5, and 7. In groups III and IV these studies were also performed on days 14, 21, and 28. Serum creatinine was determined on day 7 in all rats and on day 28 in groups III and IV. Groups I and II and groups III and IV were killed at the end of days 7 and 28, respectively. Kidneys and urinary bladders were graded subjectively for inflammation and fibrosis. Inflammation and fibrosis scores in kidney and bladder tissues were not different between DDAVP or saline-injected rats in cystitis groups at weeks 1 and 4. No fibrosis was found in any of the urinary bladders on histological examination. Ascendant pyelonephritis was detected in each of the four rats in DDAVP-administered and saline-administered cystitis groups. The histopathologic scores of the renal tissue with pyelonephritis showed no correlation with the daily urine volume, the positive test results for urine leukocyte esterase with dipstick test, the urine culture results for E. coli based on colony-forming unit per milliliter, or serum creatinine levels in cystitis groups. It was found that the administration of DDAVP to cystitis groups did not increase the risk of ascendant pyelonephritis.

Altered muscarinic receptor subtype expression and functional responses in cyclophosphamide induced cystitis in rats

In the in vitro study, it was investigated whether the expression of muscarinic receptors and cholinergic responses were altered in the situation of experimental cystitis. Rats were treated with cyclophosphamide intraperitoneally and the bladders were excised 36-100 h later. Immunohistochemistry and immunoblotting showed all subtypes of the muscarinic receptor (M1-M5) to be present in the specimens from inflamed urinary bladders and controls. In the cyclophosphamide-treated rats, the expression of muscarinic M5 receptors was increased by more than 40 times (p<0.01; n=8) both in the smooth muscle and the urothelium. Both the maximal contractile response to carbachol and to a high potassium concentration was approximately halved in cyclophosphamide-treated tissues, whereas the reduction was substantially greater in response to low carbachol concentrations (<EC(50)). The administration of 4-DAMP inhibited the carbachol-induced contractile responses of inflamed strips less potently than of controls, whereas pirenzepine and methoctramine showed equipotency in the two groups. The nitric oxide synthase inhibitor l-NNA increased the contractile effect of carbachol in inflamed detrusor strips, while it had no effect in controls. Immunoblotting showed endothelial nitric oxide synthase (eNOS) to be up-regulated in cystitis, and immunohistochemistry revealed the change to occur in the urothelium and in the suburothelial layer. The alteration of cholinergic detrusor responses in cyclophosphamide-treated rats depends mainly on a general detriment of contractility but also on indirect effects possibly via nitric oxide synthesis. The most prominent histological alterations occurred in the urothelium in which muscarinic M5 receptors increased in particular. The study further underlines that the urothelium may play significant roles in the pathogenesis of urinary bladder disorders such as interstitial cystitis.

Enhanced ATP release from rat bladder urothelium during chronic bladder inflammation: Effect of botulinum toxin A

The effects of mechanoreceptor stimulation and subsequent ATP release in cyclophosphamide evoked chronic bladder inflammation was examined to demonstrate: (1) whether inflammation modulates ATP release from bladder urothelium and (2) whether intravesical botulinum toxin A administration inhibits urothelial ATP release, a measure of sensory nerve activation. ATP release was measured from rat bladders in a Ussing chamber, an apparatus that allows one to separately measure resting and mechanoreceptor evoked (e.g. hypoosmotic stimulation) ATP release from urothelial and serosal sides of the bladder. Cystometry was utilized to correlate changes in ATP release with alterations in the frequency of voiding and non-voiding bladder contractions, in vivo measures of bladder afferent activity. The resting urothelial release of ATP was not significantly affected by either cyclophosphamide or botulinum toxin A treatment. However, evoked ATP release following hypoosmotic stimulation was significantly increased (i.e. 94%) in chronic cyclophosphamide treated bladder urothelium compared to control bladders. In addition, botulinum toxin A treatment significantly reduced hypoosmotic shock induced ATP release in cyclophosphamide treated animals by 69%. Cystometry revealed that cyclophosphamide and botulinum toxin A treatments altered non-voiding (i.e. cyclophosphamide increased, botulinum toxin A decreased) but not voiding contraction frequency suggesting that alterations in urothelial ATP release selectively diminished underlying bladder C-fiber nerve activity. Finally, intravesical instillation of botulinum toxin A did not affect ATP release from the serosal side implying that its effects were confined to the urothelial side of the bladder preparation.

Anandamide-evoked activation of vanilloid receptor 1 contributes to the development of bladder hyperreflexia and nociceptive transmission to spinal dorsal horn neurons in cystitis

The role of anandamide in the development of inflammatory hyperalgesia and visceral hyperreflexia was studied in the rat urinary bladder. Animals were given intraperitoneal cyclophosphamide injection, which evokes painful hemorrhagic cystitis accompanied by increased bladder reflex activity. The vanilloid receptor 1 [transient receptor potential vanilloid 1 (TRPV1)] antagonist capsazepine, applied onto the serosal surface of bladders, significantly reduced the hyperreflexia. Mass spectrometric analysis revealed that cyclophosphamide injection significantly and persistently increased the anandamide content of bladder tissues. The increase in the anandamide content paralleled the development of reflex hyperactivity. Anandamide (1-100 microm), applied onto the serosal surface of naive bladders, increased the reflex activity in a concentration-dependent manner. Repeated anandamide applications did not produce desensitization of the response. The anandamide-evoked effect was blocked by capsazepine or by instillation of resiniferatoxin, the ultrapotent TRPV1 agonist, into the bladders 24 hr before the anandamide challenge. The cannabinoid 1 receptor antagonist SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide] significantly increased the potency of anandamide in enhancing bladder reflex activity in naive but not in cyclophosphamide-injected animals. Application of the fatty acid amide hydrolyze inhibitor palmitoylisopropylamine onto the serosal surface of bladders also increased the reflex activity both in naive and cyclophosphamide-injected rats. This latter effect in naive animals was blocked by capsazepine and by resiniferatoxin pretreatment. Finally, intravesical instillation of anandamide (50 microm) increased c-fos expression in the spinal cord, which was reduced by capsazepine or by resiniferatoxin pretreatment. These results suggest that anandamide, through activating TRPV1, contributes to the development of hyperreflexia and hyperalgesia during cystitis.

[Expression of cancer-related indices in different types of cystitis glandularis and clinical significance thereof]

OBJECTIVE

To explore the rationality of clinical typing of cystitis glandularis (CG) and the potential of cancerization of different types of CG.

METHODS

Flow cytometry was performed to examine the ploidy of 25 fresh bladder specimens of patients with CG resected during operation, 13 high risk type and 12 low risk type, and 7 specimens of normal mucosa of bladder, by calculating the DNA index (DI). Immunohistochemistry was used to detect the expression of proliferating cell nuclear antigen (PCNA), mutant p53, p21ras, Rb, and bcl-2 in other 38 preserved specimens of CG resected during operation, 18 high risk type and 20 low risk type, and 5 specimens of normal bladder.

RESULTS

The DI was 1.00 +/- 0.03 in the normal bladder group, 1.05 +/- 0.07 in the high risk type CG group, and 1.01 +/- 0.05 in the low risk type CG, without significant differences between any 2 groups (t = -1.639, P = 0.115). The expression of PCNA and expression of p53 were negative in the low risk group, and PCNA was expressed in 5 specimens of high risk type CG (27.8%), and not expressed in the low risk type CG (P = 0.017). p53 was expressed in 4 specimens of high risk type CG (22.2%), and not expressed in the low risk type CG (P = 0.041). There were no significant differences in the expression of p21, Rb, and bcl-2 between the high and low risk groups.

CONCLUSION

High risk type and low risk type of CG are both benign lesions. High risk type CG may be more likely to cancerate. It is reasonable to distinguish different types of CG. p53 gene may play an important role in the canceration of CG.

MACROPHAGE MIGRATION INHIBITORY FACTOR IS RELEASED AS A COMPLEX WITH α1-INHIBITOR-3 IN THE INTRALUMINAL FLUID DURING BLADDER INFLAMMATION IN THE RAT

PURPOSE

Macrophage migration inhibitory factor (MIF) is released into intraluminal fluid (ILF) during bladder inflammation in the rat. We investigated the forms of MIF that are released. We examined MIF release after subcutaneous substance P (SP) or intravesical capsaicin and studied proteins associated with excreted MIF in ILF.

MATERIALS AND METHODS

Anesthetized male rats with the bladder isolated from the kidneys were injected with SP subcutaneously (saline vehicle) or with intravesical capsaicin (vehicle, 0.1 mM and 1 mM). After 1 hour the ILF was removed and MIF levels were determined using enzyme-linked immunosorbent assay or Western blotting procedures under native, nonreducing and reducing conditions. Mass spectrometry was used to identify proteins associated with MIF in ILF and results were verified by immunoprecipitation.

RESULTS

SP and intravesical capsaicin increased the total amount of MIF in ILF. MIF was found in high molecular weight complexes that resolved into 2 bands under nonreducing conditions. SP and capsaicin differentially increased the MIF bands. Mass spectrometry determined that MIF was complexed with acute phase proteins. MIF immunoprecipitation followed by Western blotting confirmed that MIF was complexed to alpha1-inhibitor-3.

CONCLUSIONS

MIF is complexed with alpha1-inhibitor-3, a member of the alpha-2-macroglobulin proteinase inhibitor family, in the rat. Although SP and capsaicin increased the total amount of MIF detected by enzyme-linked immunosorbent assay in ILF, the patterns of MIF complexes elicited by these 2 treatments were different. These findings suggest that in association with other proteins MIF forms part of a complex elicited by bladder inflammation.

Elimination of rat spinal neurons expressing neurokinin 1 receptors reduces bladder overactivity and spinal c-fos expression induced by bladder irritation

Substance P (SP) binding to neurokinin 1 receptors (NK1R) in the spinal cord reportedly plays an important role in the micturition reflex as well as in nociceptive responses. We therefore investigated the effect of ablation of NK1R-expressing neurons in the spinal cord using saporin, a ribosome-inactivating protein, conjugated with [Sar9, Met (O2)11]SP, a specific ligand of NK1R (SSP-saporin), on the micturition reflex in rats. In female Sprague-Dawley rats, SSP-saporin (1.0 or 1.5 microM) or saporin (1.5 microM) only was injected through an intrathecal catheter implanted at the L6-S1 level of the spinal cord. Three weeks after intrathecal administration of SSP-saporin, NK1R immunoreactivity in lamina I of the spinal cord was significantly reduced, but cystometric parameters in awake rats were not altered. Instillation of capsaicin (15 microM) into the bladder of normal rats induced bladder overactivity. This response to capsaicin was significantly suppressed in SSP-saporin-treated animals. SSP-saporin treatment also decreased c-fos expression in the dorsal horn of the spinal cord induced by instillation of capsaicin into the bladder. These data indicate that NK1R-expressing neurons in the superficial layer of the dorsal horn play an important role in transmission of nociceptive afferent information from the bladder to induce bladder overactivity and spinal c-fos expression elicited by bladder irritation. Toxin-induced damage of NK1R-expressing neurons in the lumbosacral spinal cord may provide an effective modality for treating overactivity and/or nociceptive responses in the bladder without affecting normal micturition.

Up-regulation of protease activated receptors in bladder after cyclophosphamide induced cystitis and colocalization with capsaicin receptor (VR1) in bladder nerve fibers

PURPOSE

Studies suggest that protease activated receptors (PARs) are mediators of inflammation and repair. Studies suggest a neurogenic mechanism for PAR2 in inflammation and the fact that interaction between PAR2 and transient receptor vanilloid receptor (TRPV1 or VR1) are important for the induction and maintenance of inflammatory pain.

MATERIALS AND METHODS

We examined the expression of PAR2 to 4 in bladder urothelium and detrusor muscle whole mounts in controls, female rats and those treated with cyclophosphamide (CYP) acutely (4 and 48 hours) or chronically (every third day for 10 days) using Western blot and immunohistochemical techniques. Colocalization of PARs in nerve fibers and VR1 immunoreactive nerve fibers was determined by double labeling techniques for protein gene product and capsaicin receptor (VR1).

RESULTS

Western blot revealed up-regulation (1.5 to 9.4-fold) of PAR2 to 4 in bladder after cystitis. Immunohistochemistry revealed PAR2 to 4 expression in urothelial and detrusor muscle cells, and in nerve fibers in the subepithelial bladder layer. Confocal microscopy revealed colocalization of PAR2 to 4 with protein gene product 9.5 and VR1, suggesting that PARs are distributed in C-fiber bladder nerves.

CONCLUSIONS

These studies demonstrate that 1) CYP induced cystitis up-regulates PAR2 to 4 expression in the bladder, 2) PAR2 to 4 is expressed in urothelium, detrusor muscle and bladder nerve fibers in control and CYP treated rats, and 3) bladder C-fibers and bladder afferent cells in dorsal root ganglia express PAR2 to 4. These results suggest the involvement of PARs in bladder inflammation that contributes to altered sensory processing and reflex function.

Expression and function of bradykinin B1 and B2 receptors in normal and inflamed rat urinary bladder urothelium

The bladder urothelium exhibits dynamic sensory properties that adapt to changes in the local environment. These studies investigated the localization and function of bradykinin receptor subtypes B1 and B2 in the normal and inflamed (cyclophosphamide (CYP)-induced cystitis) bladder urothelium and their contribution to lower urinary tract function in the rat. Our findings indicate that the bradykinin 2 receptor (B2R) but not the bradykinin 1 receptor (B1R) is expressed in control bladder urothelium. B2R immunoreactivity was localized throughout the bladder, including the urothelium and detrusor smooth muscle. Bradykinin-evoked activation of this receptor elevated intracellular calcium (EC(50) = 8.4 nM) in a concentration-related manner and evoked ATP release from control cultured rat urothelial cells. In contrast, B1R mRNA was not detected in control rat urinary bladder; however, following acute (24 h) and chronic (8 day) CYP-induced cystitis in the rat, B1R mRNA was detected throughout the bladder. Functional B1Rs were demonstrated by evoking ATP release and increases in [Ca(2+)](i) in CYP (24 h)-treated cultured rat urothelial cells with a selective B1 receptor agonist (des-Arg(9)-bradykinin). Cystometry performed on control anaesthetized rats revealed that intravesical instillation of bradykinin activated the micturition pathway. Attenuation of this response by the P2 receptor antagonist PPADS suggests that bradykinin-induced micturition facilitation may be due in part to increased purinergic responsiveness. CYP (24 h)-treated rats demonstrated bladder hyperactivity that was significantly reduced by intravesical administration of either B1 (des-Arg(10)-Hoe-140) or B2 (Hoe-140) receptor antagonists. These studies demonstrate that urothelial expression of bradykinin receptors is plastic and is altered by pathology.

H-ras Immunohistochemical Expression and Molecular Analysis of Urinary Bladder Lesions in Grazing Adult Cattle Exposed to Bracken Fern

Chronic ingestion of bracken fern (Pteridium spp.) by cattle produces upper alimentary tract and urinary bladder tumours causing a syndrome called bovine enzootic haematuria (BEH). Previous studies demonstrated ptaquiloside-DNA adducts and mutations in the h-ras gene in ileal epithelial cells of bracken fern-fed calves. Systematic inspection of the bladder mucosa of grazing cattle (n=126) from bracken-fern areas was carried out in a slaughterhouse. Of the 126 slaughterhouse cattle, 46 showed macroscopical lesions of the bladder. These bladders, together with six others known to have BEH, were examined histopathologically and by H-ras immunohistochemistry. Thirteen affected bladders were also examined by H-ras molecular analysis to detect mutations. Macroscopical and histological study of urinary bladder lesions found at the slaughterhouse revealed chronic cystitis (34.1%) and tumours (2.4%). There was significantly increased immunohistochemical expression of H-ras (P<0.05) in chronic cystitis (H-ras=53.24%) and bladder tumours (H-ras=63.60%) as compared with normal urinary bladders (H-ras=4.32%). A silent mutation (D38D) was detected in one animal with a mixed bladder tumour. The prevalence of urinary bladder lesions (chronic cystitis and tumours) obtained at the slaughterhouse was higher than expected. This study demonstrates that close inspection of urinary bladders of adult grazing cows is necessary to prevent possible human exposure to bracken-fern carcinogens. The absence of mutations in the codons of h-ras studied did not exclude the presence of polymorphisms in other regions of the gene (promoter or regulation sequences) or in other genes (belonging or not to the ras family) that significantly affect the H-ras protein.

Involvement of estrogen in the pathogenesis of cyclophosphamide-induced cystitis in rats

We examined the effects of ovariectomy and castration on the histology of cyclophosphamide (CP)-induced cystitis in rats. The animals were injected with CP (100 mg/kg) or saline intraperitoneally twice with an intervening 4 d and were euthanized at 1 or 2 wk after the initial CP administration. Saline treatment did not cause an apparent histological change in the bladder regardless of surgery, i.e., ovariectomy, castration, and sham-operation. CP treatment resulted in submucosal edema, urothelial damage, hemorrhage, and leukocyte infiltration in the bladder at 1 wk after the initial CP administration regardless of surgery. However, these histological changes were more severe in ovariectomized rats than in the sham-operated rats. In contrast, there were no significant differences in CP-induced histological changes in the bladder between castrated and sham-operated groups. We further examined the role of estrogen and progesterone on the CP-induced histology in the bladder by the replacement with estrogen only or estrogen plus progesterone for 2 wk in overiectomized rats. Estrogen treatment ameliorated CP-induced histological changes compared to oil treatment, whereas estrogen plus progesterone treatment did not produce any differences in the histology of the bladder compared to estrogen treatment. These results suggest that estrogen may play a role in the pathogenesis of bladder inflammation.

MODULATING BLADDER NEURO-INFLAMMATION: RDP58, A NOVEL ANTI-INFLAMMATORY PEPTIDE, DECREASES INFLAMMATION AND NERVE GROWTH FACTOR PRODUCTION IN EXPERIMENTAL CYSTITIS

PURPOSE

In interstitial cystitis (IC) inflammation induces and perpetuates neurotrophic changes in the bladder, resulting in the symptoms of frequency, urgency and pain. RDP58 (NH2-arg-norleucine (nle)-nle-arg-nle-nle-nle-gly-tyr-CONH2) (Sangstat Corp., Fremont, California) is a novel synthetic peptide that inhibits early signal transduction pathways for the expression of inflammatory cytokines. In this study we evaluated the effects of intravesical RDP58 on an established model of cystitis.

MATERIALS AND METHODS

Mice were catheterized and equal volumes of Escherichia coli lipopolysaccharide (LPS) or saline were instilled into the bladder. After 45 minutes the bladders were drained and distilled water or RDP58 (1 mg/ml) was instilled for 30 minutes. At 24 hours later the bladders were excised and cultured for analysis of tumor necrosis factor-alpha (TNF-alpha), substance P (SP) and nerve growth factor (NGF) production, as quantified by enzyme-linked immunosorbent assay.

RESULTS

LPS caused severe inflammation in mouse bladders compared with controls. Exposure to LPS increased the levels of TNF-alpha, SP and NGF production compared with controls (each p <0.05). In LPS exposed mice RDP58 significantly decreased inflammatory parameters by 82% 24 hours after treatment (p <0.05). Within 4 hours RDP58 abolished TNF-alpha production and at 24 hours TNF-alpha remained undetectable. RDP58 also significantly decreased SP and NGF production in LPS exposed bladders by more than 40% and 85%, respectively (each p <0.05).

CONCLUSIONS

Inflammatory models of cystitis result in increased levels of TNF-alpha, SP and NGF production in the bladder, paralleling the hypothesized neuro-inflammatory etiology of IC. RDP58 decreases inflammation and neurotrophic factors in vivo and it may potentially treat bladder disorders with an inflammatory component, such as IC.

CYCLOPHOSPHAMIDE INDUCED CYSTITIS ALTERS NEUROTROPHIN AND RECEPTOR TYROSINE KINASE EXPRESSION IN PELVIC GANGLIA AND BLADDER

PURPOSE

We examined neurotrophin and receptor tyrosine kinase (Trk) expression in the bladder and major pelvic ganglia (MPG) after cyclophosphamide induced cystitis in rats.

MATERIALS AND METHODS

The bladder and MPG were used in immunohistochemical studies, enzyme-linked immunoassays and Western blots for nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), TrkA and TrkB. Bladder postganglionic MPG cells were labeled by tracing techniques.

RESULTS

NGF and BDNF expression was decreased in the bladder of all rats after cystitis (p < or =0.001). NGF and BDNF expression was increased in the MPG in male rats with cystitis (p < or =0.01). Cells expressing TrkA and TrkB immunoreactivity (IR) increased 78% to 81% in the MPG in male rats with cystitis. TrkA-IR or TrkB-IR bladder postganglionic cells increased 50% to 74% with cystitis. Cystitis increased TrkA-IR 5 to 10-fold and TrkB-IR 10 to 12-fold in detrusor muscle. TrkA-IR and TrkB-IR were prominent in control urothelium but decreased with cystitis. After cystitis TrkB-IR nerve fibers and TrkA-IR cellular infiltrates were more apparent compared to controls.

CONCLUSIONS

Cystitis decreases bladder NGF and BDNF expression, whereas MPG expression is increased. This change may reflect neurotrophin release at the bladder and retrograde transport to the MPG. TrkA-IR and TrkB-IR are increased in bladder postganglionic cells and bladders with cystitis. This increase may reflect a shift in Trk staining from urothelium to detrusor muscle and nerve fibers with cystitis. Neurotrophin/Trk interactions in the bladder and MPG may contribute to bladder overactivity with cystitis.

Protease-activated receptor stimulation activates a Ca2+-independent phospholipase A2 in bladder microvascular endothelial cells

Increased mast cell numbers and mast cell activation represent one of the prevalent etiologic theories for interstitial cystitis, an inflammatory condition in the bladder. This study was designed primarily to determine whether increased mast cell tryptase in the bladder wall may play a role in activating bladder endothelial cell phospholipase A(2) (PLA(2)), leading to increased inflammatory phospholipid metabolite accumulation, which may propagate the inflammatory process. We stimulated human bladder microvascular endothelial cells with thrombin or tryptase and measured the activation of PLA(2) and the production of multiple membrane phospholipid-derived inflammatory mediators. Thrombin and tryptase stimulation resulted in activation of a Ca(2+)-independent PLA(2), leading to increased release of arachidonic acid and prostacyclin and increased production of platelet-activating factor. These responses were blocked completely by pretreatment of human bladder microvascular endothelial cells with the Ca(2+)-independent PLA(2)-selective inhibitor bromoenol lactone. The combination of increased prostacyclin and platelet-activating factor in the bladder circulation may result in vasodilation and increased polymorphonuclear leukocyte adherence to the endothelium and may facilitate recruitment of polymorphonuclear leukocytes to the bladder wall of patients with interstitial cystitis.

Upregulation of corticotropin-releasing hormone gene expression in the paraventricular nucleus of cyclophosphamide-induced cystitis in male rats

We examined the effects of cyclophosphamide (CP)-induced cystitis on the expression of corticotropin-releasing hormone (CRH) mRNA in the paraventricular nucleus (PVN) and the serum levels of adrenocorticotropic hormone (ACTH) using in situ hybridization histochemistry and radioimmunoassay. In addition, the expression of AVP heteronuclear (hn) RNA and neuronal nitric oxide synthase (nNOS) mRNA was also examined in the PVN of a CP-induced cystitis model. We found that the levels of CRH mRNA were significantly increased in the PVN at 2 h after intraperitoneal administration of CP compared to those in saline-treated rats. The CRH mRNA levels in the PVN peaked at 12 h after CP administration and the levels were still significantly higher than those in saline-treated group at 24 h after CP administration. The serum ACTH levels in CP-treated group were also significantly higher compared to those in saline-treated group at any of the time points examined. Unlike previous findings showing upregulation of nNOS mRNA and AVP hnRNA under somatic nociceptive states, the levels of nNOS mRNA and AVP hnRNA were unchanged in the PVN following CP-induced cystitis, visceral nociceptive stimulation. These results suggest that visceral nociceptive stimulation as well as somatic nociceptive stimulation may activate the hypothalamo-pituitary axis but the hypothalamic neuroendocrine responses produced by visceral nociceptive stimulation may be different from those produced by somatic nociceptive stimulation.

Intravesical resiniferatoxin decreases spinal c-fos expression and increases bladder volume to reflex micturition in rats with chronic inflamed urinary bladders

OBJECTIVE

To evaluate the effect of intravesical resiniferatoxin on spinal c-fos expression and bladder volume at reflex micturition in rats with chronic urinary bladder inflammation.

MATERIALS AND METHODS

Of three groups of female Wistar rats, group 1 received cyclophosphamide (75 mg/kg body weight) intraperitoneally every third day (cyclophosphamide is an antitumoral agent that induces bladder inflammation after urinary excretion of its metabolite, acrolein); group 2 comprised sham-inflamed rats that received saline instead of cyclophosphamide, and group 3 received cyclophosphamide, as group 1, every third day but plus 10 nmol/L resiniferatoxin intravesically, through a urethral catheter, at 7 days. At 8 days, under urethane anaesthesia, a needle was inserted in the bladder dome and saline infused at 6 mL/h for 2 h. Finally the animals were perfusion-fixed through the ascending aorta with 4% paraformaldehyde. Transverse sections cut from L6 spinal cord segments were immunoreacted for Fos protein and positive cells in the dorsal horn counted. In a further set of equal groups the bladders were prepared in the same way under urethane anaesthesia and after 30-min of stabilization, saline was infused at 6 mL/h and the volume evoking reflex micturition determined.

RESULTS

The mean (SD) number of positive c-fos cells per spinal cord section was 85 (21), 42 (9) (P = 0.002) and 55 (10) in groups 1 to 3, respectively; the values for group 2 and 3 were similar (P = 0.22) and statistically less than that of group 1 (P = 0.02). Reflex micturition occurred at, respectively, 0.26 (0.09), 0.49 (0.18) and 0.52 (0.11) mL, being similar in group 2 and 3 (P = 0.74) but lower in group 1 (P = 0.003).

CONCLUSION

Intravesical resiniferatoxin decreases c-fos expression and increases bladder capacity in chronically inflamed rat bladders. These findings suggest that desensitizing the vanilloid receptor type 1 by intravesical resiniferatoxin is relevant to the treatment of pain and voiding frequency in patients with chronic inflammatory bladder conditions.