IRAK4 Regulates NF-κB signaling to suppress CD8 + T cell activity and promote immune evasion in glioblastoma...

Glioblastoma remains a highly aggressive brain tumor characterized by immune evasion, limiting the efficacy of immunotherapies. This study investigates the role of interleukin-1 receptor-associated kinase 4 (IRAK4) in modulating CD8⁺ T cell activity and immune escape in glioblastoma development. Employing high-throughput proteomics, we identified 1,205 differentially expressed proteins in glioblastoma samples, with IRAK4 significantly upregulated. Bioinformatic analyses revealed IRAK4's involvement in the nuclear factor-kappa B (NF-κB) signaling pathway, critical for immune regulation. In vitro experiments demonstrated that IRAK4 overexpression suppressed CD8⁺ T cell cytotoxicity, reducing lactate dehydrogenase release and cytokine production (interferon-gamma and tumor necrosis factor-alpha), while IRAK4 knockout enhanced these functions. Co-culture assays with glioblastoma cell lines (GL261 and G422) showed that IRAK4 overexpression promoted tumor cell proliferation, migration, and invasion, while decreasing apoptosis. Conversely, IRAK4 knockout attenuated these effects. Inhibition of NF-κB signaling with Triptolide reversed IRAK4-mediated suppression of CD8⁺ T cell activity and tumor progression. Further investigations revealed that it can promote the phosphorylation of IκBα, leading to its ubiquitination and subsequent degradation, thereby activating the NF-κB signaling pathway and ultimately suppressing CD8⁺ T-cell activity. IN vivo, an orthotopic mouse model confirmed that IRAK4 overexpression increased tumor growth and reduced CD8⁺ T cell infiltration, effects mitigated by Triptolide. These findings highlight IRAK4 as a key regulator of NF-κB-mediated immune evasion in glioblastoma, suggesting its potential as a therapeutic target to enhance CD8⁺ T cell-based immunotherapy. This study provides novel insights into glioblastoma's immune regulatory mechanisms and supports the development of targeted immunotherapies.