Metabolomics reveals the immunomodulation of endophytic fungal exopolysaccharides from Cyclocarya paliurus in RAW264.7 macrophages via MAPK pathway and metabolic reprogramming.

Three endophytic fungal exopolysaccharides (EPSs) from Cyclocarya paliurus can enhance the proliferation of RAW264.7 and exhibit obvious immunomodulatory effects. The immunomodulatory mechanism information of endophytic fungal EPSs from Cyclocarya paliurus in RAW264.7 macrophages is still relatively lacking. This study explores how these EPSs affect RAW264.7 phagocytosis and the secretion of nitric oxide (NO), cytokines, and reactive oxygen species (ROS), and examines their metabolic reprogramming and immune-activation mechanisms in RAW264.7 cells via cell metabolomics. Results showed that all three EPSs enhance phagocytic activity and levels of NO, cytokines, and ROS in RAW264.7 cells, and induced M1 macrophage polarization via the mitogen-activated protein kinase (MAPK) pathway. Metabolomics reveals that Monascus purpureus exopolysaccharide (MPE) and Aspergillus versicolor exopolysaccharide (AVE) cause marked changes in energy, amino acid, and lipid metabolism. Penicillium citrinum exopolysaccharide (PCE) uniquely enhances immunity without lipid metabolism disruption or severe oxidative stress. Collectively, PCE emerged as a promising immunomodulator with a favorable risk-benefit profile in vitro. It effectively triggers immune responses, minimizing metabolic disruption and oxidative stress, which highlights its potential for developing immune regulators.