A combination of ssGSEA and mass cytometry identifies immune microenvironment in muscle‐invasive bladder cancer

BACKGROUND: Muscle‐invasive bladder cancer (MIBC) is a heterogeneous disease with varying clinical courses and responses to treatment. To improve the prognosis of patients, it is necessary to understand such heterogeneity. METHODS: We used single‐sample gene set enrichment analysis to classify 35 MIBC cases into immunity‐high and immunity‐low groups. Bioinformatics analyses were conducted to compare the differences between these groups. Eventually, single‐cell mass cytometry (CyTOF) was used to compare the characteristics of the immune microenvironment between the patients in the two groups. RESULTS: Compared with patients in the immunity‐low group, patients in the immunity‐high group had a higher number of tumor‐infiltrating immune cells and greater enrichment of gene sets associated with antitumor immune activity. Furthermore, positive immune response‐related pathways were more enriched in the immunity‐high group. We identified 26 immune cell subsets, including cytotoxic T cells (Tcs), helper T cells (Ths), regulatory T cells (Tregs), B cells, macrophages, natural killer (NK) cells, and dendritic cells (DCs) using CyTOF. Furthermore, there was a higher proportion of CD45+ lymphocytes and enrichment of one Tc subset in the immunity‐high group. Additionally, M2 macrophages were highly enriched in the immunity‐low group. Finally, there was higher expression of PD‐1 and Tim‐3 on Tregs as well as a higher proportion of PD‐1+ Tregs in the immunity‐low group than in the immunity‐high group. CONCLUSION: In summary, the immune microenvironments of the immunity‐high and immunity‐low groups of patients with MIBC are heterogeneous. Specifically, immune suppression was observed in the immune microenvironment of the patients in the immunity‐low group.