Autoimmunity to urothelial antigen causes bladder inflammation, pelvic pain, and voiding dysfunction: a novel animal model for Hunner-type interstitial cystitis
Yoshiyuki Akiyama, Jianrong Yao, Karl J. Kreder, Michael A. O’Donnell, Susan K. Lutgendorf, Dan Lyu, Daichi Maeda, Haruki Kume, Yukio Homma, Yi Luo
Abstract
Recent evidence revealed that Hunner-type interstitial cystitis (HIC) is a robust inflammatory disease potentially associated with enhanced immune responses and histologically characterized by epithelial denudation and lymphoplasmacytic infiltration with frequent clonal expansion of infiltrating B cells. To date, few animal models that reproduce the histological and clinical correlates of HIC have yet been established. In the present study, we aimed to develop a novel animal model for HIC via autoimmunity to the bladder urothelium using the transgenic mouse model (URO-OVA) that expresses the membrane form of the model antigen ovalbumin (OVA) as a self-antigen on the bladder urothelium. OVA-specific lymphocytes (splenocytes) were generated by immunization of C57BL/6 mice with OVA protein and injected intravenously into URO-OVA mice. The splenocytes from OVA-immunized C57BL/6 mice showed increased interferon (IFN)-γ production in response to OVA stimulation in vitro. URO-OVA mice adoptively transferred with OVA-primed splenocytes developed cystitis exhibiting histological chronic inflammatory changes such as remarkable mononuclear cell infiltration predominantly composed of T and B lymphocytes, increased vascularity, and mucosal hyperemia in the bladder at days 7– 28 with a peak at day 21 tested. No systemic inflammation was found in cystitis-induced URO-OVA mice, nor was any inflammation found in wild-type C57BL/6 mice adoptively transferred with OVA-primed splenocytes. Along with bladder inflammation, URO-OVA mice demonstrated significantly increased pelvic nociceptive responses, voiding dysfunction, and upregulated mRNA expression levels for IFN-γ, tumor necrosis factor-α (TNF-α), and substance P precursor in the bladder. This model reproduces the histological and clinical features of human HIC, providing a novel model for HIC research.