Immunometabolism: Is cyanide a missing link between metabolic pathways and immune function?

Immunometabolism is an emerging field that explores how metabolic pathways shape immune cell function, fate, and response. Immune cells undergo dynamic metabolic reprogramming to meet the energetic and biosynthetic demands of activation, differentiation, and effector activity. While glycolysis and oxidative phosphorylation (OxPhos) are well-established regulators of immune responses, recent discoveries suggest that endogenously produced cyanide may serve as a novel modulator of mitochondrial metabolism. Traditionally viewed as a toxic compound, cyanide is now being recognized for its potential role in regulating OxPhos through inhibition of complex IV in the electron transport chain, thereby influencing the balance between glycolysis and mitochondrial respiration. This review synthesizes current knowledge on the metabolic regulation of immune cells-including T cells, macrophages, dendritic cells, B cells, and natural killer (NK) cells-and highlights the role of core pathways such as glycolysis, fatty acid oxidation (FAO), and amino acid metabolism. It also explores how cyanide formation and metabolism intersect with innate immunity, particularly through the generation of thiocyanate and its role in antimicrobial defense. Furthermore, the review discusses how nutritional status integrate with metabolic cues to fine-tune immune responses. Finally, the clinical implications of immunometabolic regulation are examined in the context of autoimmune diseases, cancer, infections, and metabolic disorders. The potential of cyanide as a therapeutic modulator of immune metabolism is considered, offering new perspectives on immune regulation and disease intervention.