Work

IL18BP links antigen processing and presentation programs to a dendritic cell-enriched immunoregulatory state in colorectal cancer

Year: 2026

Type: article

Abstract: Background Antigen processing and presentation (APP) is required for tumor immune recognition, but its relationship with the immune landscape in colorectal cancer (CRC) remains incompletely defined. In this study, APP-related transcriptional programs were used as the starting point to identify immune-cell-associated biomarkers with prognostic and immunotherapeutic relevance in CRC. Methods Six public CRC bulk cohorts were analyzed to define APP-related molecular states. Weighted gene co-expression network analysis and four machine-learning frameworks, including Boruta, LassoLR, Pamr, and XGBoost, were applied to prioritize genes linked to APP activity. Single-cell analysis was performed with an atlas of 121 samples and 169,427 cells to identify the cellular origin of the candidate gene. Immune infiltration, cancer-immunity-cycle activity, immune checkpoint blockade (ICB) response, predicted drug response, somatic mutation patterns, and in vitro function were then evaluated. Results Two APP-associated patterns were identified and showed different survival outcomes and immune landscapes. Network- and machine-learning-based screening prioritized IL18BP as the main APP-associated candidate. Higher IL18BP expression was associated with longer survival and an immune-active phenotype, including stronger antigen-presentation signals, increased immune infiltration, checkpoint-related signatures, and cancer-immunity-cycle activation. Single-cell profiling showed that IL18BP was preferentially enriched in dendritic cells (DCs), linking the APP-derived bulk signature to a DC-centered immunoregulatory compartment. Across nine external ICB-treated cohorts, IL18BP showed response-classification performance. Drug-response prediction and somatic mutation analyses identified additional features associated with IL18BP-defined groups. In CRC cell lines, IL18BP knockdown increased proliferation, migration, and invasion. Conclusion These findings identify IL18BP as a DC-enriched, APP-associated biomarker in CRC. By connecting APP programs in bulk tumors with DC-level expression patterns at single-cell resolution, this study positions IL18BP as an APP-associated marker of a DC-enriched immune state. These findings support further evaluation of IL18BP for prognostic and immunotherapy stratification in colorectal cancer but do not establish a causal APP-DC-IL18BP pathway.

Source: Frontiers in Immunology

DOI: 10.3389/fimmu.2026.1973858