Polyunsaturated Fatty Acid-Bound a-Fetoprotein Promotes Immune Suppression by Altering Human Dendritic Cell Metabolism

a-Fetoprotein (AFP) is expressed by stem-like and poor outcome hepatocellular cancer tumors and is a clinical tumor biomarker. AFP has been demonstrated to inhibit dendritic cell (DC) differ-entiation and maturation and to block oxidative phosphorylation. To identify the critical metabolic pathways leading to human DC functional suppression, here, we used two recently described single-cell profiling methods, scMEP (single-cell metabolic profiling) and SCENITH (single-cell energetic metabolism by profiling translation inhibition). Glycolytic capacity and glucose dependence of DCs were significantly increased by tumor-derived, but not normal cord blood-derived, AFP, leading to increased glucose uptake and lactate secretion. Key molecules in the electron transport chain in partic-ular were regulated by tumor-derived AFP. These metabolic changes occurred at mRNA and protein levels, with negative impact on DC stimulatory capacity. Tumor-derived AFP bound signifi- cantly more polyunsaturated fatty acids (PUFA) than cord blood- derived AFP. PUFAs bound to AFP increased metabolic skewing and promoted DC functional suppression. PUFAs inhibited DC differentiation in vitro, and o)-6 PUFAs conferred potent immu-noregulation when bound to tumor-derived AFP. Together, these findings provide mechanistic insights into how AFP antagonizes the innate immune response to limit antitumor immunity.Significance: a-Fetoprotein (AFP) is a secreted tumor protein and biomarker with impact on immunity. Fatty acid-bound AFP promotes immune suppression by skewing human dendritic cell metabolism toward glycolysis and reduced immune stimulation.

Automated summary

Hepatocellular cancer tumors express a-Fetoprotein (AFP), which inhibits dendritic cell differentiation and maturation, and blocks oxidative phosphorylation. Tumor-derived AFP increases glycolytic capacity and glucose dependence of dendritic cells, leading to increased glucose uptake and lactate secretion. Furthermore, AFP bound with polyunsaturated fatty acids (PUFAs) skews dendritic cell metabolism and promotes immune suppression.