The effects of a galectin‐3 inhibitor on bladder pain syndrome in mice with cyclophosphamide‐induced cystitis

Abstract Aims To explore the effect of blocking galectin‐3 in the bladder pain syndrome associated with interstitial cystitis. Methods A galectin‐3 inhibitor was used to treat mice with cyclophosphamide‐induced cystitis. The expression of galectin‐3 in bladder tissues and urine was examined by immunohistochemistry and enzyme‐linked immunosorbent assay (ELISA), respectively. Suprapubic‐pelvic pain, bladder voiding, bladder pain‐like nociceptive behavior, and referred hyperalgesia were assessed. The weights of the bladders were also measured, and inflammatory cell infiltration and inflammatory cytokine levels were examined by histopathological evaluation. The inflammatory cytokines interleukin 1β (IL‐1β), nerve growth factor (NGF), IL‐6, and tumor necrosis factor α (TNF‐α) were measured by ELISA. Results Increases in galectin‐3 levels, inflammation, bladder weight, and bladder pain‐related symptoms were observed in bladders with cyclophosphamide‐induced cystitis. Administration of the galectin‐3 inhibitor significantly mitigated bladder pain‐related symptoms and inflammatory response. In response to the 500 μM dose of the galectin‐3 inhibitor, nociceptive behaviors, nociceptive score, and bladder‐to‐body weight ratios were reduced by 65.1%, 65.3%, and 40.3%, respectively, while 500 μM Gal‐3 inhibitor increased pelvic pain threshold by 86.7%. Moreover, galectin‐3 inhibitor treatment inhibited the inflammation. Compared to untreated CYP‐induced mice, there were significant changes in the levels of IL‐1β (41.72 ± 2.05 vs. 18.91 ± 2.26 pg/mg tissues), NGF (9.64 ± 0.38 vs. 1.88 ± 0.05 pg/mg tissues), IL‐6 (42.67 + 1.51 vs. 21.26 + 2.78 pg/mg tissues, and TNF‐α (22.02 ± 1.08 vs. 10.70 ± 0.80 pg/mg tissues) in response to the highest dose of the Gal‐3 inhibitor subgroup (500 μM), and 500 μM Gal‐3 inhibitor reduced mast cell infiltration ratios by 71.8%. Conclusions The galectin‐3 inhibitor relieved pelvic pain, urinary symptoms, and bladder inflammation in mice with cyclophosphamide‐induced cystitis. Thus, galectin‐3 inhibitors may be novel agents in interstitial cystitis treatment.