Immune cell profiles of patients with interstitial cystitis/bladder pain syndrome

Abstract

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a disorder characterized by bladder pain upon filling which severely affects quality of life. Clinical presentation can vary. Local inflammatory events typify the clinical presentation of IC/BPS patients with Hunner lesions (IC/BPS-HL). It has previously been proposed that B cells are more prevalent in HL, but understanding their exact role in this environment requires a more complete immunological profile of HL. We characterized immunological dysfunction specifically in HL using immunohistochemistry. We detected significantly more plasma cells (50× increase, p < 0.0001), B cells (28× increase, p < 0.0001), T cells (3× increase, p < 0.0001), monocytes/macrophages (6× increase, p < 0.0001), granulocytes (4× increase, p < 0.0001), and natural killer cells (2× increase, p = 0.0249) in IC/BPS patients with HL than in unaffected controls (UC). Patients with IC/BPS-HL also had significantly elevated urinary levels of IL-6 (p = 0.0054), TNF-α (p = 0.0064) and IL-13 (p = 0.0304) compared to patients with IC/BPS without HL (IC/BPS-NHL). In contrast, IL-12p70 levels were significantly lower in the patients with HL than in those without these lesions (p = 0.0422). Different cytokines were elevated in the urine of IC/BPS patients with and without HL, indicating that different disease processes are active in IC/BPS patients with and without HL. Elevated levels of CD138+, CD20+, and CD3+ cells in HL are consistent B and T-cell involvement in disease processes within HL.

Fig. 1

Cystoscopic images of Hunner Lesions (HL) from 2 different patients with Interstitial Cystitis/Bladder Pain Syndrome with Hunner Lesions (IC/BPS-HL) compared to healthy bladder tissue. HLs are typically circumscribed, reddened mucosal areas with small vessels radiating towards a central scar and are seen in about 5 to 10 percent of patients with IC/BPS [4]. Diagnosis is made via cystoscopy and confirmed by biopsy

Fig. 2

A Images of biopsied tissues from patients with Interstitial Cystitis/Bladder Pain Syndrome with Hunner Lesions (IC/BPS-HL) and unaffected controls (UC) stained for immune cell markers. Cross sections of bladder urothelium viewed at ×40 magnification and stained for Hematoxylin and Eosin (H&E, nucleus/cytoplasm), CD3 (pan T cells), CD20 (B cells), CD138 (plasma cells), CD14 (monocytes), and CD15 (neutrophils/eosinophils). Biopsies were performed on 48 patients diagnosed with IC/BPS-HL and 2 unaffected controls (UC). Thin (4–6 µm) cross sections of bladder tissue were then stained with either H&E or specific CD markers. Images of Hunner lesions and control tissue are shown. B Average cell marker counts found in the bladder biopsy samples of patients with IC/BPS-HL vs. UC. Cells positive for each marker were quantified per high-dry field (×400), taken in the area of maximum diffuse infiltration by the inflammatory cells. Data are expressed as mean ± SEM. C Relative proportions of cells displaying each cell marker in UC and IC/BPS-HL cohorts. The average proportion of Cluster of Differentiation (CD)-20 positive (CD20+) B cells (IC/BPS-HL: 12%; UC: 2%) and CD138+ plasma cells (IC/BPS-HL: 21%; UC: 2%) was much greater in pooled samples from patients with IC/BPS-HL compared to pooled samples from unaffected controls, while the percentage of Natural Killer cells (IC/BPS-HL: 7%; UC: 15%), Monocytes (IC/BPS-HL: 18%; UC: 15%), and Neutrophils (IC/BPS-HL: 14%; UC: 13%) did not differ significantly between the two cohorts. The relative abundance of cells displaying the CD3 T cell marker fell from 52% among the unaffected controls to 29% among the IC/BPS-HL cohort

Fig. 3

Urinary Cytokine concentrations in patients with Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS), and unaffected controls (UC). Nine cytokines (Interferon-γ, Interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-12p70, IL-13, and Tumor Necrosis Factor-α) were assessed using a MSD U-plex 10 spot assay (Mesoscale discovery, Catalog # K15049K-1). Individual and average (indicated by the horizontal bar) cytokine concentrations for A IL-6, B TNF-α, C IL-12p70, and D IL-13 from patients with Interstitial Cystitis/Bladder Pain Syndrome without Hunner Lesions (IC/BPS-NHL), patients with Interstitial Cystitis/Bladder Pain Syndrome without Hunner Lesions (IC/BPS-HL), and UC research participants. Data are expressed as mean ± SEM