Investigating the age and sex associated mucosal immune landscape of urinary bladder

Abstract

Abstract The incidence of BC is four times higher in males than females, however, females tend to present with a more aggressive disease, a poorer response to immunotherapy, and suffer worse clinical outcomes. Our recent novel findings demonstrated sexual dimorphism in the tumor immune microenvironment of non-muscle invasive bladder cancer, which is primarily treated with local immunotherapy. Investigating sexual dimorphism in the clinical journey of BC beyond the static local immune landscapes remains a challenge. With similarities in mucosal immune physiology between humans and mice, and the recently reported age-associated pathogenic stimuli independent inflammation observed female murine bladders, we conducted a comprehensive evaluation of the sex and age-related immune alterations in healthy murine bladders. Bulk-RNA sequencing and multiplex immunofluorescence based spatial immune profiling of normal murine bladders from male and female mice of the ages 3, 6, 9, 12, 15, and 18 months were performed. Preliminary findings from the transcriptomic analysis showed a highly altered immune landscape that exhibited sex differences in aged bladders. Spatial profiling of using markers specific to macrophages (CD163, CD11b), T lymphocytes (CD3, CD8), B lymphocytes (Pax5), activated dendritic cells (CD208), high endothelial venules (PNAd), inflammatory cells (Ly6G) and the PD-L1 immune checkpoint, showed sex and age associated differences. Older female mice had a higher density of tertiary lymphoid structures/lymphoid aggregates compared to both young female and male equivalents. Findings from this study will allow the appropriate modeling in pre-clinical studies evaluating immunotherapeutic agents for NMIBC treatment.