HISTOLOGICAL AND NEUROTROPHIC CHANGES TRIGGERED BY VARYING MODELS OF BLADDER INFLAMMATION:

Pathomechanism of Interstitial Cystitis/Bladder Pain Syndrome and Mapping the Heterogeneity of Disease

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a heterogeneous syndrome which is usually characterized by urinary frequency, nocturia, and bladder pain. Several pathomechanisms have been proposed, including uroepithelial dysfunction, mast cell activation, neurogenic inflammation, autoimmunity, and occult urinary tract infections. It is possible that an inflammatory process alters regulation of urothelial homeostasis and results in dysfunction of the bladder epithelium. Different phenotypes of IC/BPS have been explored including Hunner and non-Hunner type IC, hypersensitive bladder, and bladder pain both with and without functional somatic syndrome. Different gene expressions have also been found in different IC phenotypes. Abnormal expressions of uroplakin, chondroitin sulfate and adhesive protein E-cadherin, tight junction protein zonula occludens-1 in IC/BPS bladder suggest abnormal epithelial differentiation in this bladder disease. Analysis of inflammatory proteins, or cytokines in the urine or serum provides another diagnostic foundation forIC/BPS subtypes. The involvement of IC/BPS in systemic functional somatic syndrome and other pelvic organ diseases might also subdivide subtypes of IC/BPS. Chronic inflammation, increased urothelial apoptosis, and abnormal urothelial function are closely associated in IC bladders. This article reviews recent research on the pathomechanisms of IC, which might help us in mapping the heterogeneity of the disease.

Urinary nerve growth factor level could be a biomarker in the differential diagnosis of mixed urinary incontinence in women

OBJECTIVES

To measure urinary nerve growth factor (NGF) levels in women with stress urinary incontinence (SUI) and overactive bladder symptoms (OAB) and to assess whether urinary NGF levels can be a biomarker of detrusor overactivity (DO) in women with mixed urinary incontinence.

PATIENTS, SUBJECTS AND METHODS

Urinary NGF levels were measured in 38 women with urodynamic SUI (USI) with OAB, in 26 with urodynamic DO but no SUI, in 21 with persistent USI after anti-incontinence surgery, in 15 with de novo DO, and in 31 normal control subjects. All participants had a video-urodynamic study for the differential diagnosis of the underlying causes of UI. Urinary NGF levels were measured using an enzyme-linked immunosorbent assay and were compared among all subgroups, and corrected using urinary creatinine (Cr) levels.

RESULTS

The mean (sem) urinary NGF/Cr levels were low both in controls, at 0.06 (0.004) and in women with pure USI, at 0.056 (0.037) (P = 0.108). The NGF/Cr levels were significantly higher in women with mixed USI and DO, at 1.00 (0.244), than in controls (P < 0.001) and those with pure USI (P = 0.006), but were similar to the levels in women with pure DO, at 0.58 (0.17) (P = 0.058). The NGF/Cr levels were undetectable in women with persistent USI but were significantly higher in those with de novo DO, at 2.39 (0.90), after anti-incontinence surgery than in controls and those with USI. A urinary NGF/Cr level of >0.05 was found in 9% of women with USI, 77% with DO, 81% with mixed USI and DO, and 80% with de novo DO.

CONCLUSION

The urinary NGF level could be a potential biomarker of DO in women with mixed UI.

Endothelial nitric oxide synthase expression in neurogenic urinary bladders treated with intravesical resiniferatoxin

OBJECTIVE

To investigate endothelial nitric oxide synthase (eNOS) immunoreactivity in bladder biopsies from patients with neurogenic detrusor overactivity (NDO) before and after treatment with intravesical resiniferatoxin, and compare this with control material; the distribution of two other vascular markers, von Willebrand Factor (vWF) and the vascular endothelial growth factor (VEGF), was also studied.

PATIENTS AND METHODS

Flexible cystoscopic bladder biopsies from eight controls investigated for asymptomatic microhaematuria and 19 patients with refractory spinal NDO enrolled in a clinical trial of intravesical treatment with escalating doses of resiniferatoxin were immunostained with polyclonal rabbit antibodies for eNOS, vWF and VEGF. Fewer baseline NDO specimens (eight) were available for vWF and VEGF staining. Computerized image analysis was used to quantify immunoreactivity, and the Mann-Whitney test for statistical analysis.

RESULTS

eNOS immunoreactivity was found in the suburothelium and less often in the urothelium, with a distribution indicating a location in small blood vessels at the urothelium-suburothelium junction. Immunostaining for vWF showed a similar location. There was a trend to higher eNOS values before treatment in those responding than in those not responding to resiniferatoxin (P = 0.059), and a significant reduction in eNOS immunoreactivity after successful treatment (P = 0.016). VEGF staining was weaker but there was a significant increase in pretreatment biopsies of responders to resiniferatoxin (P = 0.048). Clinical and histopathology features were similar in both groups.

CONCLUSIONS

The trend for higher eNOS expression in patients with NDO who responded to resiniferatoxin suggests that increased vasculature or vasodilatation in the suburothelium may be necessary for successful intravesical treatment. Further studies with more patients are required to confirm this relationship and to examine the mechanisms underlying changes in vasculature with levels of bladder overactivity.

Macrophage Migration Inhibitory Factor Is Upregulated in an Endotoxin-Induced Model of Bladder Inflammation in Rats

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine found in epithelial cells as preformed stores, such that MIF release can activate innate immune responses. Our identification of MIF stores in the urothelium suggests that MIF may function in the bladder's initial response to infectious stimuli, such as lipopolysaccharide (LPS). To test this hypothesis, we observed changes in MIF, cyclooxygenase-2 (COX-2) and c-fos in the bladder, L6-S1 spinal cord, dorsal root ganglion (DRG), and major pelvic ganglion (MPG) and MIF changes in the prostate following intravesical LPS. Intravesical LPS induced bladder edema and leukocyte infiltration, as well as increased MIF protein and mRNA in the bladder and lumbosacral spinal cord. Expression of immediate-early gene c-fos, a transcription factor used as a marker of neuronal activation, increased in the L6-S1 spinal cord and L6-S1 DRG of rats that received LPS. We conclude that significant increases in bladder MIF expression and protein in response to intravesical LPS may represent part of this organ's initial innate immune response. In addition, MIF upregulation may represent a neural response to visceral inflammation. Finally, changes in prostate MIF content after intravesical LPS suggest that MIF may be involved in viscerovisceral interactions associated with chronic pelvic pain syndromes.