Interstitial cystitis (IC) is a chronic bladder disease with urinary frequency, bladder discomfort or bladder pain of unknown etiology. Based on cystoscopic findings, patients with IC are classified as either Hunner-type/classic IC (HIC), presenting with a specific Hunner lesion, or non-Hunner-type IC (NHIC), presenting with no Hunner lesion, but post-hydrodistension mucosal bleeding. Inflammatory cell infiltration, composed predominantly of lymphocytes, plasma cells and epithelial denudation, has in the past been documented as a major pathological IC finding. However, the significance of the pathological evaluation of IC, especially with regard to the difference between HIC and NHIC, has been downplayed in recent years. In this study, we performed immunohistochemical quantification of infiltrating T-lymphocytes, B-lymphocytes and plasma cells, and measured the amount of residual epithelium in urinary bladder biopsy specimens taken from patients with HIC and NHIC, and those with no IC, using image analysis software. In addition, in situ hybridization of the light chains was performed to examine clonal B-cell expansion. Lymphoplasmacytic infiltration was significantly more severe in HIC specimens than in NHIC specimens (P <0.0001). Substantial lymphoplasmacytic inflammation (≥200 cells/mm2) was observed in 93% of HIC specimens, whereas only 8% of NHIC specimens were inflamed. Plasmacytic infiltration was more prominent in HIC specimens compared with NHIC and non-IC cystitis specimens (P <0.005). Furthermore, expansion of light-chain-restricted B-cells was observed in 31% of cases of HIC. The amount of residual epithelium was decreased in HIC specimens compared with NHIC specimens and non-IC cystitis specimens (P <0.0001). These results suggest that NHIC and HIC are distinct pathological entities, with the latter characterized by pancystitis, frequent clonal B-cell expansion and epithelial denudation. An abnormality in the B-cell population may be involved in the pathogenesis of HIC.

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Objectives: To determine whether botulinum toxin type A can represent an alternative treatment option for patients with interstitial cystitis refractory to conventional therapies. Methods: This is a single-center, prospective, open labeled, randomized comparative study. Patients with refractory interstitial cystitis were randomly divided into two groups: immediate injection (group A) or 1-month delayed injection (group B) of botulinum toxin type A after allocation. The rate of treatment response (global response assessment ≥+1: slightly improved), and changes in symptom scores and frequency volume chart variables were compared between groups 1 month after allocation. Using subjects of both groups as a single cohort, predictive factors for treatment response at 1 month post-injection and the duration of response were explored. Results: A total of 34 patients (group A n = 18, group B n = 16) were allocated. The response rate was significantly higher in group A than group B (72.2% vs 25.0%, P = 0.01). All symptom measures showed significant improvement in group A than group B. When both groups were combined as a single cohort, the response rate was 73.5% at 1 month, 58.8% at 3 months, 38.2% at 6 months and 20.6% at 12 months. The mean duration of response was 5.4 months. Multivariate analysis showed that past exposure to hydrodistension more than three times correlated with better outcomes. Conclusions: Botulinum toxin type A injection could be an alternative treatment option for patients with interstitial cystitis refractory to conventional therapies, especially for those who have received repeated hydrodistensions and transurethral fulguration.

An up-regulated CXCR3 pathway and affluent plasma cell infiltration are characteristic features of Hunner type interstitial cystitis (HIC). We further examined these two features using bladder biopsy samples taken from 27 patients with HIC and 15 patients with non-IC cystitis as a control. The number of CD3-positive T lymphocytes, CD20-positive B lymphocytes, CD138-positive plasma cells, and CXCR3-positive cells was quantified by digital image analysis. Double-immunofluorescence for CXCR3 and CD138 was used to detect CXCR3 expression in plasma cells. Correlations between CXCR3 positivity and lymphocytic and plasma cell numbers and clinical parameters were explored. The density of CXCR3-positive cells showed no significant differences between HIC and non-IC cystitis specimens. However, distribution of CXCR3-positivity in plasma cells indicated co-localization of CXCR3 with CD138 in HIC specimens, but not in non-IC cystitis specimens. The number of CXCR3-positive cells correlated with plasma cells in HIC specimens alone. Infiltration of CXCR3-positive cells was unrelated to clinical parameters of patients with HIC. These results suggest that infiltration of CXCR3-positive plasma cells is a characteristic feature of HIC. The CXCR3 pathway and specific immune responses may be involved in accumulation/retention of plasma cells and pathophysiology of the HIC bladder.