Fig.1 Effect of pentosan polysulfate (PPS) on cyclophosphamide (CYP)‑ induced interstitial cystitis/bladder pain syndrome (IC/BPS) in mice. A: Comparison of mechanical pain thresholds of the mice across the groups. B-D: Urodynamic test results and their parameters in different groups. E-G: Voiding cystometry analysis of changes in voiding behavior of the mice. H: Body weight change curve of the mice. I: Bladder to body weight ratio of the mice. J-L: HE staining of the bladder tissues in different groups (Original magnification: ×10). M: PPS reduces elevated mRNA levels of inflammatory factors induced by CYP. N: PPS lowers mRNA levels of tight junction proteins in CYP-treated mice. Data are presented as Mean±SE. Statistical significance was determined by one-way ANOVA or unpaired Student's t-test. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001 vs CYP. C+P: CYP+PPS.

Fig.2 Impact of PPS on gut microbiota and its metabolites in mice with CYP-induced IC/BPS. A: Comparison of gut microbiota composition at the genus level between CYP group and C+P group (n=5). B: Venn diagram showing the shared and unique species of gut microbiota between CYP group and C+P group (n=5). C: Heatmap displaying differences in gut microbiota composition at the genus level (n=5). D: Statistical test for differences in gut microbiota composition at the genus level (n=5). E: LEfSe analysis confirms significant differences in gut microbial community composition between CYP group and C+P group. F-H: Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA) of non-targeted metabolomics data. I: Volcano plot showing differential metabolites between CYP group and C+P group. J: Comparison of DCA concentration in cecal contents between the two groups. *P<0.05.

Fig.3 Effect of fecal microbiota transplantation (FMT) from PPS-treated mice on CYP-induced IC/BPS. A: Comparison of mechanical pain thresholds among the groups. B-D: Results of urodynamic testing and their parameters. E-G: Voiding cystometry analysis. H: Bladder to body weight ratio. I-K: HE staining of the bladder tissue in the groups (×10). L: C+P-FMT reduces CYP-induced elevation of mRNA levels of inflammatory factors. M: C+P-FMT restores CYP-induced decrease of mRNA levels of tight junction proteins. Data are presented as Mean±SE. Statistical significance was determined by one-way ANOVA or unpaired Student's t-test. *P<0.05, **P<0.01, ****P<0.0001 vs CYP+FMT.

Fig.4 PPS metabolism-related product DCA alleviates bladder epithelial inflammatory injury by activating TGR5. A: Expression levels of inflammatory factors in SV-HUC-1 cells treated with different concentrations of LPS. B: Expression levels of tight junction proteins in SV-HUC-1 cells treated with different concentrations of LPS. C: Viability of SV-HUC-1 cells treated with different concentrations of DCA. D: DCA reduces LPS-induced inflammatory factor expression levels. E: DCA restores LPS-induced reduction of expressions of tight junction proteins in SV-HUC-1 cells. F: DCA stimulates bile acid receptor mRNA expression in SV-HUC-1 cells. G: SBI-115 inhibits the effect of DCA on inflammatory factor expressions in LPS-induced SV-HUC-1 cells. H: SBI-115 inhibits the effect of DCA on tight junction protein expressions in LPS-induced SV-HUC-1 cells. Data are presented as Mean±SE. Statistical significance was determined by one-way ANOVA or unpaired Student's t-test. **P<0.01, ***P<0.001, ****P<0.0001 vs Control (A-C and F-H) or LPS (D-E).