Modulating miRNA-367-3p Expression by Kaempferol Alleviates Experimental Autoimmune Encephalomyelitis: Targeting Fpn1-Dependent Ferroptosis and cAMP/CREB/CNTF Signaling

Multiple sclerosis (MS) is a progressive, immune-mediated demyelinating disorder of the central nervous system (CNS). Kaempferol (KAM), a dietary bioflavonoid found in many edible and medicinal plants, exhibits significant neuroprotective effects in various immunological and neurological disorders; however, its therapeutic potential in MS remains largely unexplored. This study aimed to investigate the protective effects of KAM and the underlying molecular mechanisms using an experimental autoimmune encephalomyelitis (EAE) mouse model of MS. 40 female C57B1/6 mice were assigned to 4 groups: Normal control [saline (i.d.) + DMSO (i.p.)]; KAM [saline (i.d.) + KAM (50 mg/kg/d, i.p.)]; EAE [MOG35–55 immunization (i.d.) + DMSO (i.p.)]; and EAE + KAM [MOG35–55 immunization (i.d.) + KAM (50 mg/kg/d, i.p.)]. The brain and spinal cord were dissected for biochemical, molecular, histopathological, electron microscopic, and immunohistochemical analysis. KAM administration efficiently reduced clinical scores and ameliorated neural cytomorphological abnormalities. KAM profoundly combated iron overload and effectively upregulated ferroportin1 (Fpn1)-encoding gene expression. Furthermore, KAM valuably counteracted neuronal ferroptosis chiefly by restoring the Slc7A11/GSH/GPX4 axis. KAM considerably attenuated proinflammatory cytokine IL-17 and chemokine CCL-19. Intriguingly, KAM promoted axonal remyelination as indicated by an observable escalation in myelin basic protein content through activating the cAMP/CREB/ciliary neurotrophic factor (CNTF) axis. Collectively, for the first time, these findings demonstrated KAM’s neuroprotective potency against EAE, considering its antioxidant, anti-ferroptotic, immunomodulatory, anti-inflammatory, and neurotrophic properties, primarily mediated by inhibiting Fpn1-mediated ferroptosis, activating the cAMP/CREB/CNTF axis, and enhancing miRNA-367-3p expression. Accordingly, miRNA-367-3p has been proposed as an upcoming therapeutic target for MS, and KAM could be a promising treatment option for MS patients.