Profiling the Urinary Microbiota in Men with Positive versus Negative PD-L1 Expression for Non-muscle Invasive Bladder Cancer

Background Urinary microbiota is associated with the recurrence of bladder cancer, but the underlying mechanism remains unclear. The notion that microbiota can upregulate PD-L1 expression in tumors to promote immune escape have been demonstrated. We hypothesized that the urinary microbiota may be involved in the recurrence and progression of non-muscle invasive bladder cancer (NMIBC) by upregulating the PD-L1 expression. For proving this hypothesis, we firstly performed this study to characterize the potential urinary microbial community possibly associated with PD-L1 expression in male patients with NMIBC. Results The subjects (aged 43–79 years) based on their PD-L1 immunohistochemical results were divided into PD-L1-positive group (P group) and PD-L1-negative group (N group) respectively. We observed that P group exhibited higher species richness and diversity (based on Observed species and Ace index, both P P Leptotrichia, Roseomonas, and Propionibacterium) and decrease of some bacterial genera (e.g.,Prevotella and Massilia) were observed in P group as compared with N group. These findings indicate that these genera may affect the expression of PD-L1 through some mechanisms to be studied. PICRUSt analysis showed that several pathways involved in the metabolism of chemical compounds and immune-related disease were enriched in the PD-L1 negative group. Conclusion Our data indicate that urinary microbiota may be an important determinant of PD-L1 expression in male NMIBC patients. The findings of our study may facilitate subsequent study on the role and mechanism of urinary microbiota in the recurrence of NMIBC and may also pave a new way for the better application of PD1 or PD-L1 blockers in bladder cancer in the future.