Fig. 1

Overview of the study design, which was divided into two main parts. In the first part, we collected 34 pairs of BLCA tissues and their corresponding paracancerous tissues from a local hospital. The infiltration levels of Bregs in these tissues were quantified using dual immunohistochemical staining. Additionally, we examined the malignant phenotypes of BLCA cells T24 and SW780 when co-incubated with Bregs. In the second part, we gathered Breg-related genes from various sources and developed a Breg-related signature. This signature was created using LASSO regression, random forest analysis, and multivariate Cox regression based on the TCGA-BLCA cohort. To validate the prognostic value of the risk signature, we tested it on six independent BLCA cohorts and local BLCA samples. Furthermore, we assessed the predictive ability of the signature for immunotherapeutic sensitivity using two cohorts that received anti-PD1/PDL1 treatment and the TIDE algorithm. Finally, we conducted cellular functional experiments to investigate the regulatory ability of CSH1, a gene involved in the risk signature, in the expansion of Bregs. BLCA, bladder cancer; Bregs, regulatory B cells; LASSO, Least Absolute Shrinkage and Selection Operator; TCGA, The Cancer Genome Atlas; TIDE, Tumor Immune Dysfunction and Exclusion