Inflammatory synaptopathy is a prominent pathogenic process in multiple sclerosis (MS) induced by imbalanced immune system homeostasis. Its persistence causes excitotoxic neuronal damage, leading to motor and cognitive deficits. Although many advances have been made in MS treatment, the development of effective strategies for managing disease progression driven by excitotoxic synaptic dysfunctions is of great significance. Gut dysbiosis is commonly associated with both MS and obesity and high-fat diet (HFD) can exacerbate disease by acting on gut microbiota. Since gut microbiota can shape the immune response and brain functions, we propose to target gut dysbiosis by dietary supplementation of prebiotics and probiotics (Pre-Pro) to treat synaptopathy in both human and experimental model of MS, even when exacerbated by HFD. Overall, this project aims at unveiling the anti-inflammatory and neuroprotective pathways activated by Pre-Pro supplementation to modulate the immune-synaptic axis.