Metabolic Dysfunction and T-Cell Exhaustion in Colorectal Cancer: Mechanisms, Microenvironment Remodeling, and...

Colorectal cancer (CRC) remains a major cause of cancer-related morbidity and mortality worldwide. Metabolic disorders such as obesity, diabetes mellitus, dyslipidemia, and metabolic syndrome are associated with CRC risk. Metabolic abnormalities may contribute to colorectal tumorigenesis and reshape the tumor immune microenvironment, which in turn influence immune dysfunction and therapeutic resistance. Exhausted CD8⁺ T cells exhibit impaired effector function, sustained inhibitory receptor expression, and transcriptional and epigenetic reprogramming. Metabolic stressors within the CRC microenvironment may modulate T-cell function and exhaustion-associated states. Additionally, other immune populations (natural killer cells, macrophages, myeloid-derived suppressor cells, dendritic cells, and regulatory T cells) may develop distinct dysfunctional or immunosuppressive states. Recent single-cell and spatial studies have indicated the heterogeneity of these immunometabolic interactions in CRC. This review examines the interactions of the systemic and tumor-associated metabolic alterations with T-cell exhaustion and other forms of immune dysfunction in CRC. We discuss the influence of glucose, lipid, amino acid, and mitochondrial metabolism, hypoxia, microbiota-derived metabolites, and chronic inflammation in shaping tumor-immune interactions. Finally, we reviewed therapeutic strategies targeting immunometabolic pathways and their potential integration with immune checkpoint blockade. Overall, understanding these interactions may help identify immunometabolic vulnerabilities for informing precise therapeutic strategies for CRC.