Physical exercise confers systemic immunomodulatory benefits, yet the molecular mediators linking metabolic stress to immune cell reprogramming remain incompletely defined. N-lactoyl-phenylalanine (Lac-Phe), a lactate-phenylalanine conjugate synthesized by carnosine dipeptidase 2 (CNDP2), has emerged as a critical exercise-derived metabolite that bridges peripheral energy metabolism with central and peripheral immune regulation....