IFN-γ Orchestrates Coordinated Immunosuppression in Head and Neck Squamous Cell Carcinoma Through JAK-STAT-IRF8 Signaling: A Transcriptome-Wide Computational Analysis

BackgroundInterferon-gamma (IFN-{gamma}) is the primary effector cytokine of adaptive anti-tumor immunity, yet it paradoxically induces a potent immunosuppressive tumor microenvironment (TME). The full mechanistic scope of this paradox in head and neck squamous cell carcinoma (HNSC) has not been characterized at the transcriptomic scale. MethodsUsing TCGA HNSC RNA-seq data (n = 522), we applied an integrated computational pipeline: Spearman correlation analysis, principal component analysis (PCA), UMAP, K-means clustering (k = 4), Random Forest regression, deep neural networks, permutation importance, JAK-STAT cascade mapping, and DNN-based transcriptome-wide mediation analysis across 57 IFN-{gamma} pathway and 78 immunosuppressive genes. ResultsIFN-{gamma} pathway activity was universally and positively correlated with six immunosuppressive axes, including checkpoints (CD274; LAG3; IDO1), Tregs, myeloid suppression, and tryptophan catabolism. K-means clustering identified four immunologically distinct tumor subgroups. DNN models predicted suppressive TME. Permutation importance identified IRF8 as the dominant mediator linking IFN-{gamma} signaling to immunosuppression. DNN mediation analysis identified PDCD1LG2 (PD-L2) as the strongest intermediary between IFNG and PD-L1 regulation, followed by JAK2 and GBP5. ConclusionsIFN-{gamma} orchestrates coordinated immunosuppression in HNSC through JAK-STAT-IRF8 signaling. PDCD1LG2 and JAK2 are actionable mediators of this paradox, supporting combination strategies co-targeting IFN-{gamma}-induced checkpoint induction and direct checkpoint blockade in HNSC immunotherapy. GRAPHICAL ABSTRACT