Bisphenol A induces ACSL4-associated ferro-aging-like urothelial injury: Implications for Hunner-type interstitial cystitis

Hunner-type interstitial cystitis (HIC) is an inflammatory subtype of interstitial cystitis/bladder pain syndrome marked by persistent urothelial injury and bladder dysfunction. Bisphenol A (BPA) can disturb redox and inflammatory homeostasis, but its relevance to HIC-associated urothelial vulnerability remains unclear. This study examined whether acyl-CoA synthetase long-chain family member 4 (ACSL4) contributes to BPA-associated ferro-aging-like urothelial injury. Among non-pregnant adult women, higher creatinine-corrected urinary BPA was associated with a phenotype predominantly characterized by urgency urinary incontinence (UUI), and the primary Mendelian randomization analysis suggested higher interstitial cystitis (IC) risk with genetically proxied BPA exposure. Integrated transcriptomic, BPA-target, and machine-learning analyses prioritized ACSL4 as a consistent HIC-associated candidate. HIC tissues showed higher ferro-aging-like transcriptional scores and ACSL4 expression; single-cell analyses further identified disease-associated urothelial cell-state remodeling, with higher ACSL4 expression and SenePy scores in HIC urothelial cells. Structure-based modeling suggested a plausible BPA-ACSL4 interaction, while cellular thermal shift assay (CETSA) indicated BPA-associated thermal stabilization of ACSL4. In primary human urothelial cells, BPA increased ACSL4 mRNA and protein expression, lipid peroxidation, iron accumulation, p21 expression, senescence-associated β-galactosidase (SA-β-Gal) positivity, inflammatory signaling, and barrier impairment, together with reduced Lamin B1 and ZO-1 expression and transepithelial electrical resistance (TEER). ACSL4 silencing and vitamin C attenuated these changes. In mice, PRGL493 and vitamin C each attenuated multiple BPA-induced bladder abnormalities. Together, these findings support an ACSL4-associated ferro-aging-like urothelial injury phenotype involving iron-lipid stress, senescence-associated changes, inflammation, and barrier impairment, with relevance to selected features of HIC.