FNDC5 and Parkinson disease: In PD models using α-synuclein preformed fibrils or MPTP, exogenous irisin consistently reduces NLRP3 inflammasome activation, lowers IL-1β, IL-6 and TNF-α levels, restores antioxidant defenses, rescues mitochondrial membrane potential, and preserves dopaminergic neurons with concomitant improvement in motor behavior, indicating a causally supported, reproducible pathway from irisin to reduced oxidative stress, improved mitophagy, and neuroprotection [9,10].