Aberrant p53 fuels macrophage immunoregulatory polarization and refractory clinical outcome in urothelial carcinoma.

Urothelial carcinoma (UC) exhibits extensive infiltration of tumor-associated macrophages (TAMs). As the most frequently altered gene in UC, TP53 is recognized not only as a guardian of genomic integrity, but also as a potential architect of the tumor immune microenvironment (TIME). However, how aberrant p53 status, comprising TP53 mutation (TP53 Mut) and p53 abnormal expression (p53Abn), correlates with TAM phenotypic and functional heterogeneity and their reciprocal interactions within the TIME landscape remains incompletely defined. This study integrated single-cell RNA sequencing, immunohistochemistry, and flow cytometry to delineate TAM phenotypes and map distinct immune landscapes stratified by p53 status. Clinical relevance was assessed in a multicohort dataset of 962 patients with UC with comprehensive clinicopathological annotations. Single-cell profiling revealed distinct TAM subsets closely linked to p53 status. Interferon-primed TAMs, marked by CXCL9, CXCL10, CXCL11 and IDO1, predominated in p53 wild-type (p53WT) tumors, whereas immune regulatory TAMs (Reg-TAMs), marked by SPP1, MARCO, SLC2A1 and INHBA, were enriched in p53Abn tumors. This divergent distribution highlighted a profound, p53-associated TAM heterogeneity. Clinically, high TAMs infiltration was consistently associated with worse overall survival predominantly in p53Abn or TP53 Mutpatients across three independent cohorts (Zhongshan Hospital, Fudan University Shanghai Cancer Center and The Cancer Genome Atlas). Furthermore, high TAMs infiltration correlated with poorer responses to both platinum-based chemotherapy and anti-programmed cell death-ligand 1 immunotherapy specifically in the p53Abn or TP53 Mut subgroup. Notably, aberrant p53 status was strongly coupled with a distinct metabolic reprogramming in TAMs, favoring lipid catabolism and immunoregulatory polarization. Trajectory analysis revealed a skewed differentiation axis in p53Abn tumors toward terminally differentiated Reg-TAMs. Immunohistochemistry and flow cytometry validated increased immunosuppressive TAM subsets in p53Abn UC. Additionally, p53Abn tumors exhibited an altered CD4+ T-cell landscape, enriched for suppressive subsets (regulatory, exhausted, and metallothionein-expressing T cells) coexisting with Reg-TAMs, potentially associated with immune suppression via the predicted SPP1-CD44 axis. In UC, aberrant p53 status correlates with a remodeled TIME, characterized by metabolically reprogrammed, immunosuppressive TAMs. These TAMs co-evolve with suppressive CD4+ T cells, suggesting a coordinated immunosuppressive network potentially involving SPP1-CD44 signaling. Together, this specific genotype-phenotype coupling delineates a profoundly immunosuppressive ecosystem that likely impedes immune clearance and limits therapeutic efficacy.