The Role of Gut-Brain Axis in Modulating the Impact of Sterile Inflammation on Neuroimmune Responses in Neurodegenerative Diseases — Alzheimer’s Disease and Parkinson’s Disease

Background: Emerging evidence has demonstrated the important role of gut microbiota in host physiology, affecting host immunity. The gut-brain axis has been identified between the central nervous system and the gut microbiota, indicating bidirectional communication between the two systems. Summary: Microbial imbalance (in other words, gut dysbiosis) can lead to chronic systemic inflammation, resulting in neuroinflammation as an example of sterile inflammation. Three major pathways in causing neuroinflammation from chronic systemic inflammation by the gut microbiota via the gut-brain axis are discussed throughout the article. This includes the inflammasome signaling, altered permeability of the blood-brain barrier by the short-chain fatty acids (SCFAs), and oxidative stress. Key messages: Through understanding that gut dysbiosis is capable of modulating neuroinflammation, the use of probiotics in neurodegenerative diseases can be investigated to assess their therapeutic potential. Increasing clinical studies show positive results on the use of probiotics in neurodegenerative diseases, yet further evidence is required to validate their clinical effectiveness.