fig1

Figure 1. Possible mechanisms that microbiota promotes initiation of bladder cancer. Lesion starts with invasion of microbiota, which usually damages epithelial barrier through multiple virulence factors^[31,40] and increases the chance that microbiota interacts with bladder cells. Formation of intracellular bacteria and incomplete clearance^[41] from innate immune cells leads to chronic infection with an inflammatory environment characterized by various inflammatory mediators and immune cells. Chronic barrier destruction leads to more interactions between microbes and host, and persistent damage-repair loop (an inappropriate host response) of bladder epithelium plus inflammation environment increases the possibility of gene mutation and disrupts the intracellular signaling pathways^[36]. Overall, multiple microbiota-mediated hits may contribute to the carcinogenesis of bladder cancer and further research needs to evaluate this relevance.