Abstract P118: Interleukin-Inflammatory Cancer-Associated Fibroblast Educate IL1B TAMs that Correlate with Recurrence and Chronic Inflammation

Abstract

Tumour-associated macrophages (TAMs) are key in shaping the tumour microenvironment, often synergizing with cancer-associated fibroblasts (CAFs) to drive angiogenesis, immune suppression and exclusion. While single-cell omics has revealed a heterogeneous spectrum of TAMs and CAFs, studies investigating their crosstalk often overlook subset-specific interactions despite having consequential implications for targeted treatment. We sought to determine the interactions of TAM and CAF subsets in HPV- head and neck squamous cell carcinoma (HNSCC) by characterizing the subpopulations through single-cell RNA sequencing (scRNA-seq) of primary tumours. We utilize in silico cell-cell communication and spatial transcriptomics to predict interacting subsets before validating through in vitro coculture. Finally, deconvoluting RNA-seq from the TCGA-HNSC cohort, we showed that interacting populations were proportionally correlated and investigated their clinical significance through Kaplan-Meier analysis. Overall, IL1B TAMs and interleukin inflammatory CAFs (IL-iCAFs) stood out as the most strongly interacting subsets, predominantly communicating through paracrine factors. Spatially, they formed an insular communication network with monocytes and were proportionally correlated across patients in the TCGA-HNSC cohort. In vitro, patient-derived CAFs were induced into iCAFs and co-cultured with THP1 macrophages. RNA-seq revealed that THP1 macrophages adopted the gene signature and biological pathways of in vivo IL1B TAMs including IL6/JAK/STAT, TNFA and IL2/STAT5 pathways after co-culture with iCAFs but not with cancer cells. Clinically, infiltration of IL1B TAMs and IL-iCAFs were associated with poor disease-specific survival, while IL1B TAMs were further associated with 5 year postoperative recurrence. By comparing primary tumours of patients who relapsed versus those that remained cancer-free, we identified enhanced inflammatory signaling and communication from IL1B TAMs to Tregs via IL1B-IL1R2 and TNF-TNFR2; both implicated in immune exhaustion. In conclusion, this study points toward a potential role for IL-iCAFs and IL1B TAMs in chronic inflammation and immune dysregulation, justifying further research into the targetability of this axis during treatment.