We previously reported that mice with experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS), develop profound urinary bladder dysfunction. Because neurogenic bladder in MS patients causes marked bladder remodeling, we next examined morphometric and molecular alterations of the bladder in EAE mice. EAE was created in female SJL/J mice by immunization with the p139-151 encephalitogenic peptide of myelin proteolipid protein in complete Freund's adjuvant, along with intraperitoneal injections of Bordetella pertussis toxin. Seventy days after immunization, mice were scored for the level of neurological impairment and then killed. Spinal cord sections were assessed for demyelination, inflammation, and T cell infiltration; the composition of the bladder tissue was measured quantitatively; and gene expression of markers of tissue remodeling and fibrosis was assessed. A significant increase in the bladder weight-to-body weight ratio was observed with increasing neurological impairment, and morphometric analysis showed marked bladder remodeling with increased luminal area and tissue hypertrophy. Despite increased amounts of all tissue components (urothelium, smooth muscle, and connective tissue), the ratio of connective tissue to muscle increased significantly in EAE mice compared with control mice. Marked increases in mRNA expression of collagen type I α(2), tropoelastin, transforming growth factor-β3, and connective tissue growth factor (CTGF) were observed in EAE mice, as were decreased levels of mRNAs for smooth muscle myosin heavy chain, nerve growth factors, and muscarinic and purinergic receptors. Our results suggest that bladder remodeling corresponding to EAE severity may be due to enhanced expression of CTGF and increased growth of connective tissue.

The cause of chronic pelvic pain in interstitial cystitis/painful bladder syndrome (IC/PBS) remains unclear; autoimmunity is a possible etiology. We have recently shown that injection of a single immunogenic peptide of uroplakin 3A (UPK3A 65-84) induces experimental autoimmune cystitis (EAC) in female BALB/cJ mice that is unique among experimental models in accurately reflecting both the urinary symptoms and pelvic pain of IC/PBS. The aim of this project was to identify the roles of mast cells and mast cell chemoattractant/activator monocyte chemoattractant protein-1 [chemokine (C-C motif) ligand 2 (CCL2)] in the allodynia in this model. We immunized 6- to 8-wk-old female BALB/cJ mice with UPK3A 65-84 peptide and, 5–40 days later, observed increased responses to stimulation of the suprapubic abdominal and hindpaw surfaces with von Frey monofilaments compared with mice injected with adjuvant alone. Suprapubic and hindpaw tactile allodynia responses by EAC mice were blocked by instillation of lidocaine into the bladder but not by lidocaine in the uterus, confirming the bladder as the source of the hypersensitivity. Markedly increased numbers of activated mast cells and expression of CCL2 were found in the bladder after immunization with UPK3A 65-84. Hypersensitive responses were inhibited by mast cell stabilizer cromolyn sodium and antagonists of histamine receptors 1 and 2. Furthermore, BALB/cJ mice with deletion of the Ccl2 or chemokine (C-C motif) receptor 2 gene exhibited markedly reduced allodynia and accumulation of mast cells after UPK3A 65-84 immunization. These results show that UPK3A 65-84 immunization causes chronic visceral allodynia and suggest that it is mediated by CCL2-driven mast cell accumulation in the bladder.