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TIM4 has previously been associated with antitumor immunity, yet the pattern of expression and the function of this receptor across human cancer tissues remain poorly explored. Here we combined extensive immunolabeling of human tissues with in silico analysis of pan-cancer transcriptomic data sets to explore the clinical significance of TIM4 expression. Our results unveil that TIM4 is expressed on a fraction of cavity macrophages (CATIM4+MΦ) of carcinoma patients. Moreover, we uncover a high expression of TIM4 on macrophages of the T-cell zone of the carcinoma-associated tertiary lymphoid structures (TLSTIM4+MΦ). In silico analysis of a pan-cancer data set revealed a positive correlation between TIM4 expression and markers of B cells, effector CD8+ T cells, and a 12-chemokine signature defining tertiary lymphoid structure. In addition, TLSTIM4+MΦ were enriched in cancers displaying microsatellite instability and high CD8+ T-cell infiltration, confirming their association with immune-reactive tumors. Both CATIM4+MΦ and TLSTIM4+MΦ express FOLR2, a marker of tissue-resident MΦ. However, CATIM4+MΦ had a higher expression of the immunosuppressive molecules TREM2, IL10, and TGFβ as compared with TLSTIM4+MΦ. By analyzing a scRNA sequence data set of tumor-associated myeloid cells, we identified two TIM4+FOLR2+ clusters coherent with CATIM4+MΦ and TLSTIM4+MΦ. We defined specific gene signatures for each subset and found that the CATIM4+ MΦ signature was associated with worse patient survival. In contrast, TLSTIM4+MΦ gene signature positively correlates with a better prognosis. Together, these data illustrate that TIM4 marks two distinct macrophage populations with distinct phenotypes and tissue localization and that may have opposing roles in tumor immunity., (©2022 American Association for Cancer Research.)

Ovarian carcinomas (OCs) are poorly immunogenic and immune checkpoint inhibitors (ICIs) have offered a modest benefit. In this study, high CD3 + T-cells and CD163 + tumor-associated macrophages (TAMs) densities identify a subgroup of immune infiltrated high-grade serous carcinomas (HGSCs) with better outcomes and superior response to platinum-based therapies. On the contrary, in most clear cell carcinomas (CCCs) showing poor prognosis and refractory to platinum, a high TAM density is associated with low T cell frequency. Immune infiltrated HGSC are characterized by the 30-genes signature (OC-IS 30 ) covering immune activation and IFNγ polarization and predicting good prognosis (n = 312, TCGA). Immune infiltrated HGSC contain CXCL10 producing M1-type TAM (IRF1 + pSTAT1Y701 + ) in close proximity to T-cells. A fraction of these M1-type TAM also co-expresses TREM2. M1-polarized TAM were barely detectable in T-cell poor CCC, but identifiable across various immunogenic human cancers. Single cell RNA sequencing data confirm the existence of a tumor-infiltrating CXCL10 + IRF1 + STAT1 + M1-type TAM overexpressing antigen processing and presentation gene programs. Overall, this study highlights the clinical relevance of the CXCL10 + IRF1 + STAT1 + macrophage subset as biomarker for intratumoral T-cell activation and therefore offers a new tool to select patients more likely to respond to T-cell or macrophage-targeted immunotherapies., Competing Interests: SG was employed by Diatech Pharmacogenetics srl and CR was employed by Dr Carola Ries Consulting. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ardighieri, Missale, Bugatti, Gatta, Pezzali, Monti, Gottardi, Zanotti, Bignotti, Ravaggi, Tognon, Odicino, Calza, Missolo-Koussou, Ries, Helft and Vermi.)